e-vison2009

E-VISION 2009

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E-VISION 2009

Advisors

Dr. Rajendra ShresthaProf. Dr. Bhakta Bahadur AleAssoc. Prof. Ramchandra SapkotaAssoc.Prof.Dr. Triratna Bajracharya

Editor-in-Chief

Roma Gurung

Editors

Anil KunwarBal Mukunda KunwarBikash ShresthaJatin Man AmatyaKundan Lal DasNilesh PradhanRavi ShahAnil Maharjan

Management

Ambish Kaji ShakyaBipul ShresthaNabin ShresthaPrakash AryalRaj Kumar ChaulagainRudramani Ghimire

Cover page design

Sabin Singh

Published by:

061 Batch Students of Department of Mechanical EngineeringPulchowk CampusInstitute of Engineering (TU)

Printing

Sigma-Carts Printing and LogisticsChauni, Kathmandu

Editorial

“…This effort that we put in is a continuation for the milestone that our seniors set, and we hope that this journal will remain the powerful tool, that bridges the gap between the teachers, working engineers, alumni and the students for years to come…” are the inspiring words we would like to put forward reinforcing the editorial message of the 3rd and 4th issues of E-VISION, published respectively by the 054 and 059 batch students of the Department of Mechanical Engineering, Pulchowk Campus. Therein, we have added the words “working engineers” and “alumni” in order to broaden the purpose and implications of this praiseworthy work initiated by our inspiring seniors.

This 5th issue of E-VISION is put forward with optimism that the glorious culture set up by our elders will be continued with several improvements and evolutions that need to be addressed in order to meet the challenges and opportunities of time. As the publication of this journal has not been so regular, we urge our juniors to give an uninterrupted continuity to it as a living asset of the Mechanical Engineering Department.

In contrary to the era of the 20th century wherein easy access and flow of the information used to be quite difficult, we are today surrounded with huge piles of technological information sources nowadays owing to the globalization of information technology. So, the major concern today is the selection of the right, purposeful and useful data and information from their bulk. A bunch of information means nothing if it does not serve our purpose. In this journal, focus is given to make the presented materials more useful as well as inspiring for further exploration. All the same, the decisive evaluation is yours!

The ultimate impact of any engineering activity is doubtlessly on the society. In our context, the quality of engineering education and contributions of mechanical engineers to the transformation of Nepalese society are the two important issues. Quality in our education can be enhanced by getting acquainted with the dynamism of today’s world and redefining our roles as per changing scenarios. Challenges always surround us and solving them efficiently reflects the quality. And, the engineers dedicated in solving the challenges faced by national technology can in fact be of greater importance to this society.

Finally, we would like to express our heartfelt gratitude to all the teachers, students engineering professionals and our seniors, who have provided their invaluable articles as well as to the advertisers who have offered financial assistance. Thanks are also due to all those whose direct or indirect contributions and support triumphantly enabled in publishing the journal in this form.

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E-VISION 2009

Date: 25th February 2009

MESSAGE FROM THE DEAN

It is a great pleasure to know about the publication of the annual Engineering Journal, E-Vision from the Department of Mechanical Engineering of Pulchowk Campus.

With the rapidly changing technologies, it has become essential for the students to be updated with the recent development in their respective field of interest. And this kind of Engineering Journal provides the important information to the students and thus induces an enthusiasm to move ahead utilizing that information for the development of the country.

Lastly, I would like to express my hearty congratulation to the E-Vision team for their excellent work in publishing out this issue.

Associate Prof. Baburam Bhattrai

Dean

Institute of Engineering

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TRIBHUVAN UNIVERSITYINSTITUTE OF ENGINEERINGOFFICE OF DEAN

E-VISION 2009

Date: 25th February 2009

MESSAGE FROM THE CAMPUS CHIEF

I am very glad to know that the students of the Department of Mechanical Engineering are publishing the new issue of the annual Engineering Journal, E-Vision. I would like to appreciate the efforts of the students to publish this issue for their academic progress. This publication will be a mode of developing a better understanding within the campus and thus unite the students for the process of institutional development. I would like to express my hearty congratulations and best wishes to the E-Vision team for this endeavor.

Dr. Durga Prasad Sangraula

Campus Chief

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TRIBHUVAN UNIVERSITYINSTITUTE OF ENGINEERINGPULCHOWK CAMPUS

E-VISION 2009

Date: 25th February 2009

MESSAGE FROM THE PRESIDENT OF TEACHERS’ASSOCIATION

It is a great pleasure to acknowledge that the students of the Department of Mechanical Engineering are publishing the new issue of the annual Engineering Journal, E-Vision. The role of such engineering journals is indeed vital in the academic progress of students and also it helps to put forward the ideas and works of engineering students and professionals. I would like to congratulate to the E-Vision team for this appreciable effort and wish them further success.

Prof.Dr. Shailendra Kumar Mishra

President

Teachers Association, Pulchowk Campus

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TRIBHUVAN UNIVERSITYINSTITUTE OF ENGINEERINGPULCHOWK CAMPUSASSOCIATION OF TEACHERS

E-VISION 2009

Date: 25th February 2009

MESSAGE FROM THE HEAD OF DEPARTMENT

I would like to congratulate batch 2061/BME of mechanical engineering department for publishing E-Vision. The effort on publication of the journal is to become familiar with modern technology. I wish for its success and the journal will be helpful for the students, researchers and professionals.

Mechanical Engineering Department is offering bachelor in mechanical engineering, Master of Science in renewable energy engineering and doctorate in mechanical engineering. We focus on academic as well as professionalism of our graduates. Our graduates are involved in academic and professional fields all over the nation and abroad.

I would like to thank all our wishers contributing for the publication.

Dr. Rajendra Shrestha

Head of the Department

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TRIBHUVAN UNIVERSITYINSTITUTE OF ENGINEERINGPULCHOWK CAMPUSDEPARTMENT OF MECHANICAL ENGINEERING

E-VISION 2009

Date: 27th March 2009

MESSAGE FROM THE FSU PRESIDENT

It gives us immense pride to acknowledge that the students of the Department of Mechanical Engineering are publishing the new issue of the annual Engineering Journal, E-Vision. We would like to appreciate the students of editorial board for publishing this issue which would help to enhance the academic background of the students. We would like to congratulate to the E-Vision team for this endeavor and wish them further success. We also want to express that FSU is always supportive regarding such works.

Prakash Sapkota

President

Free Students Union

Pulchowk Campus

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TRIBHUVAN UNIVERSITYINSTITUTE OF ENGINEERINGPULCHOWK CAMPUSFREE STUDENTS’ UNION

E-VISION 2009

CONTENTS:

1 Department of Mechanical Engineering: At Glance 7

2 Biomass Energy for Cooking in Nepal -Bhakta Bahadur Ale 9

3 Issues in Nanoscience and Nanotechnology -Ram Chandra Sapkota 14

4Alternative Approach For Designing A Francis Turbine For Sand Laden Water

- Hari Prasad Neopane, Ole Gunnar Dahlhaug, Tri Ratna Bajracharya

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5Electromechanical Micro Machining(EMM)-A Promising Future Technique

-Luza Shrestha 19

6Wastewater Treatment in Nepal

-Ajay Kumar Jha Nawaraj Bhattarai

21

7 Flight Control Surface -Mahesh Kumar Marita 248 Just - in- Time (JIT) -Dhruba Panthi 26

9 Modal Vibration Mechanism in Gear Housing Walls

-Sanjeev Maharjan 29

10 Grease Trap -Naveen Kumar Mallik 32

11 Production of bio-diesel from waste oil - Alok Dhungana Anirudh Prasad Sah Mukesh Ghimire

35

12 Pioneers Of Flight - Ambish Kaji Shakya 40

13 Knowing Catia - Dave Shrestha

58

14 Moonbuggy: An Introduction -Jatin Man Amatya Ujjuma Shrestha

61

15 Carbon Nanotube In Nanotechnology - Kundan Lal Das 62

16 Material Selection : Sitka Spruce For Violin - Roma Gurung 65

17 Computational Fluid Dynamics: An Introduction - Anil Kunwar

67

18 Underground Tunnel And Tunneling Methods - Rajkumar Chaulagain 69

19Why And Why Not Of Trolley Bus Service In Kathmandu Valley

- Rudramani Ghimire 71

20 Small Scale Orthodox Tea Drying With Gasifier - Bal Mukunda Kunwar 73

21 Landfill Gas: Waste To Energy - Bikash Shrestha 75

22Space Solar Power: Energy Unlimited From Fiction To Future

- Bipul Shrestha 77

23Hydrogen Fuel Cell: A Technology For Future Energy Generation

- Prakash Aryal 79

24 Canteen Quality Survey -Nabin Shrestha Prabha Sharma

80

25 Deming’s Way - Ravi Shah

81

26 Students’ Profile 82

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DEPARTMENT OF MECHANICAL ENGINEERING: AT A GLANCE

E-VISION 2009

Brief history:

Department of Mechanical Engineering was established in the year 1975 with the provision of Certificate Level Program in Refrigeration and Air Conditioning under International Labour Organization funded project. However, at that time it co-existed under administrative unit named ERA (Electronics, Radio-electronics and Air Conditioning and Refrigeration). The three 'Section', as were called at that period, offered only certificate level courses of two years duration. The programs were later reviewed and upgraded to Diploma status with the addition of one more academic year. The Diploma programs continued for some time under the same administrative structure of ERA till the three sections grew into the Electrical, Electronics, and Mechanical departments.

As the expertise, confidence, and international exposure of the faculty and staff grew, the focus shifted naturally to the establishment of the Bachelors Program. The Department of Mechanical Engineering started the Bachelors program in the year 1995 at the central campus, the Pulchowk Campus, in Kathmandu Valley. The department moved to its own building, the D-Block, on the north side of the Campus in 1998. With the new facilities, modern equipment suitable for training and research, experienced faculty members, and increased autonomy to handle Training, Research and Consulting works, the department is poised to make its presence felt within and outside of the country. The Department currently runs Bachelor of Mechanical Engineering, Masters of Science in Renewable Energy Engineering, Doctorate education and planning to launch Masters of Engineering Management in short future.

Facilities

The department has well equipped workshop and a number of laboratories equipped with modern state of the art machines procured through global tender. The department has Fluid Mechanics, Hydraulic Machines, Heat Engines, Thermodynamics, Heat Transfer, Instrumentation and Control, Mechanisms and Machine Dynamics, Metallurgy, Pollution Control, Renewable Energy, Strength of Materials, and Mechanics of Solids laboratories. Most of theequipment is of the latest design with digital

display console. Some of the equipments are interfaced with PCs. Apart from that, the department has its own setup of twenty-four PCs interconnected through local area network with e-mail and Internet facilities. The laboratories are suitable not only for teaching, but are equally for research and consulting works. The department is capable of undertaking a variety of consultancy projects for industries in Nepal.

Furthermore Robotics Club at IOE under the supervision of Department of Mechanical Engineering has been promoting robotics and automation. With the year 2002, Robotics Club representing Nepal participated in first Asia Pacific Robot Contest in Tokyo, Japan and has been participating every year in this contest. The achievements are as follows

Additionally in the history of aviation of Nepal, the aircraft, Ultra light aircraft (Danfe), designed and fabricated by the students’ team of 059 and 060 batches from this department as their final year project, successfully accomplished a flight of 5 minutes for 4 test flights ( in 2008).

Looking into the future the Department of Mechanical Engineering would like to encourage, support and facilitate innovative projects and research works put forward by the students and teachers of the department.

Events Achievements

ABU Robocon2002, TokyoParticipated first time at the contest

ABU Robocon2003, ThailandBecame only team to reach quarter final from south Asia

ABU Robocon2004,China Won Mabuchi motor award

ABU Robocon2005,Korea Participated in the event

ABU Robocon2006,Malaysia Won Toyota award

ABU Robocon2007,Vietnam Participated in the competition

ABU Robocon2008,IndiaWon the best autonomous machine award

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E-VISION 2009

Faculty Members

S.N.

Name Qualification Post Area of expertise1 Dr. Rajendra Shrestha Ph. D.(Japan) Lecturer Fluid Mechanics, Micro-Hydropower2 Dr. B. B. Ale Ph. D.(Canada) Professor Combustion, IC Engines, Vehicle Pollution, Renewable

Energy3 Dr. C. B. Joshi Ph. D.(India) Professor Energy, Rural Technology, Fluid Machinery4 Mr. R.N Bhattarai M. Sc.(USA) Professor Refrigeration, HVAC, Pollution Control5 Mr. A. N. Nakarmi M. Sc.(Canada) Professor Engineering Management6 Mr. N. P. Shrestha M. Sc.(USSR) Assoc. Professor IC engine, Building Services, Refrigeration and A/C7 Mr. S. S. Adiga M. Sc.(UK) Assoc. Professor Machine Design8 Mr. R. C. Sapkota M. Sc.(USSR) Assoc. Professor Automobile Maintenance and Repair, Physical Metallurgy9 Mr. Susan Bajracharya M. Sc.(Canada) Assoc. Professor Refrigeration, HVAC, IAQ10 Dr. T. R. Bajracharya M. Sc.(USSR) Assoc. Professor Renewable Energy, Refrigeration, HVAC11 Mr. Sunil Risal M. Sc.(UK) Lecturer Building Services, Refrigeration and A/C12 Mr. Luza Shrestha B. E.(India) Lecturer Manufacturing, Hydraulic Machines13 Mr. P. K. Ghimire B. E.(India) Lecturer Mechanical Design and Fabrication14 Mr. R. K. Kayastha B. E.(China) Lecturer Machine Design, Metallurgy, Automation15 Mr. G. R. Paudel M. Sc.(USSR) Lecturer Manufacturing, Management16 Mr. Shreekar Pradhan M. Sc. Lecturer Instrumentation, Renewable Energy17 Mr. Shreeraj Shakya M. Sc. Lecturer Renewable Energy, Forecasting and Inventory Control18 Mr. N. P. Kafle M. Sc. Lecturer Renewable Energy19 Mr. M. C. Luitel B. E. Lecturer Thermodynamics, AutoCAD20 Mr. N. R. Bhattarai M. Sc. Lecturer Renewable Energy21 Mr. M. S. Maharjan Diploma Sr. Instructor WS Technology22 Mr. R. B. Shakya Diploma, B.Ed. Sr. Instructor WS Technology, Metallurgy23 Mr. M. K. Shrestha M. Sc. Sr. Instructor WS Technology, Pollution Control24 Mr. H. C. Manandhar Diploma Sr. Instructor Automobile, Computer Application25 Mr. Mohan B. K. C. Diploma Instructor Refrigeration and A/C26 Mr. B. P. Shakya Diploma Dy. Technician Refrigeration and A/C27 Mr. I. N. Regmi Diploma Dy. Technician Refrigeration and A/C28 Mr. Govinda Maharjan Diploma Dy. Technician General Mechanical29 Mr. Kabir Maharjan Diploma Dy. Technician General Mechanical

30 Mr. Ramesh Choudary B. E. Dy. Technician Robotics, Mechanization

StaffsContactAnanda Niketan, Pulchowk, LalitpurGPO Box: 1175, Kathmandu, Tel: 5542053,5542054; Fax977-1-5525830; E-mail: [email protected]; URL:http//mech.ioe.np

S.N. Name Post1 Mr. Ganesh L. Shrestha Asst. Administrator2 Mr. Sarad Shrestha Store-Keeper3 Mr. Rajendra Acharya Lab Boy4 Mr. Ram B. Shrestha Peon5 Mrs. Devaki Shrestha Khalasi6 Mr. Saroj Maharjan Khalasi

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BIOMASS ENERGY FOR COOKING IN NEPAL

Dr. Bhakta. Bahadur AleProfessor, Department of Mechanical Engineering

Pulchowk Campus, Institute of Engineering,Tribhuvan University

Email: <[email protected]>

E-VISION 2009

1.

Introduction

Ample and reliable accessibility of usable energy sources is one of the prerequisites for social and economic development of a country. Nepal is facing a big challenge to provide the energy to meet the basic needs of people due to poor infrastructure development and lack of fund for investment in the generation and management of energy sources. The majority of people are still dependent on inefficient use of biomass energy sources.

The total energy consumption was 355 million GJ in Nepal in 2006. In fiscal year 2005/06 traditional, commercial and renewable energy occupied 85.5%, 13.54% and 0.61% respectively of the total energy consumption (Economic Survey, MoF, 2007). Biomass and hydropower are two indigenous energy sources in Nepal. Biomass fuels (primarily fuel-wood) supply almost 86% of total energy demand and are extracted beyond the sustainable supply capability of the forests indicating continuing problem of forest depletion and localized deforestation.

The energy consumption in renewable energy has been increased from 0.53 %in FY 2004/05 to 0.61% in 2005/06. This indicates the gradual acceptance of renewable energy technologies to meet the basic needs of people by replacing fossil fuels for lighting and biomass for cooking to some extent. In 2006, there were already 90,801 solar home systems installed with the cumulative capacity of 3.6 MW (SEMAN, 2007). There are about 172,505 biogas plants operating in various districts of Nepal as of mid July 2007 (BSP-N, 2007). And till 2005, about 1,541 micro-hydro plants with cumulative capacity of 8.5 MW are operating in the country. There is high potential of wind energy in the country but it is yet to be harnessed due to diverse topography and different meteorological conditions.

The extensive use of sold biomass causes high levels of indoor air pollution in housing. It has caused significant negative health impact on women and children particularly because of the amount of time

they spend in the kitchen. They are exposed to indoor air pollution and found suffering from lungs related diseases and eye irritation.

Many efforts have been made to overcome the indoor air quality problem resulting from solid fuel use in poor housing through the promotion of fuel efficient and environmental friendly stoves and the promotion of biogas and solar energy. However, these efforts have rarely proven sustainable and have been limited in scope. Even the use of more efficient stoves cannot compensate the rising demand of firewood due to increasing population. An approach that integrates economic, technical, housing design factors, environmental sustainability and cultural requirements should be considered and implemented so that people living in poor housing can get rid of indoor air pollution.

2. Existing scenario

Fuels sources for cooking

Forest occupies about 30% of total land in Nepal. Forest land includes government forest, community forest and private forest. Depending on the income of the family and availability various types of fuels are used for cooking. Most common fuels in the rural areas are fuel wood, agricultural residues, dung, charcoal and biogas whereas in the urban areas fossil fuels (kerosene, LPG, natural gas) and electricity are used for cooking. In some urban areas woods, charcoal and briquettes are also often used. Urban wastes like waste vegetables, kitchen waste, solid waste and night soil can also used to generate biogas for cooking and heating.

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Figure 3.1 Regeneration of tree at different altitudes.

E-VISION 2009

Traditional fuels for domestic use are collected from nearby forest, farmland in rural areas whereas users buy these fuels in urban areas. Recently the biogas plants are built in many villages. Even though it is considered environmentally friendly and subsidized fuel it is still expensive for poor people. So many people in rural areas rely heavily on fuel wood and agricultural residues for cooking.

Applications of biomass

Biomass fuel has various applications in Nepal. Fuel wood is extensively used for cooking, space heating and rituals. Rice husk is the prime fuel for boilers and cooking stoves in Terai because of its easily availability and low cost compared to fossil fuels. Solid biomass is also used in brick kilns, ceramic industries and agricultural product drying purposes. Industrial applications demand significant amount of these fuels leading to even deforestation and soil erosion causing environmental degradation.

3. Biomass energy supply and demand dynamics

Energy from a tree

A 12m high tree having an average stem diameter 0.4m provides about 15GJ energy. The average fuel consumption per capita is also 15GJ in 2005 in Nepal. That means we are consuming about 25 million trees equivalent energy per year. In 2004-05, about 78% of total energy demand was met by fuel wood consumption which is equivalent to about 19 million trees of above mentioned size.

Tree regeneration at different altitudes

The firewood needed for cooking and space heating per family depends on altitude. As we go higher, that is from plain to mountain the demand of fuel wood also increases. There will be more additional demand for firewood in the region of tourist areas.

The regeneration of tree depends very much on the altitude where they are grown. Higher the altitude, slower the tree growth and lesser is the firewood regeneration. Depending on the type of trees a rough estimation of regeneration of tree can taken as follows (Sjoerd Nienhuys, 2003):

In Terai 500 m (1500 ft.) young hardwood trees can produce about 100 kg wood per year. Similarly the regeneration of tree will be 20 kg, 15 kg, 10 kg, 5 kg per year at 2,000 m (6,000 ft), 2,300m (7,000 ft), 3,000 m (9,000 ft), 3,600 m (11,000 ft) respectively. Above 4,000 m (12,000 ft.) no more trees will grow.

Biomass as a carbon neutral energy source

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E-VISION 2009

When firewood is combusted it releases CO2 which is absorbed by the newly planted trees during photosynthesis process. That is why it is carbon neutral. CO2 is one of the major contributing elements to the greenhouse effect. Trees trap CO2 from the atmosphere and make carbohydrates that are used for plant growth. They give us oxygen in return. Mature trees can absorb roughly 22 kg (48 pounds) of CO2 a year. The tree in turn releases enough oxygen to sustain two human beings. Trees grow three times faster in the tropics than in temperate zones (treesftf.org/about/cooling.htm).

Sustainable fuel wood supply estimatesWith the continuous population growth and encroachment of forest for agriculture lead the increased demand in fuel wood supply. Forest areas have been decreased and fuel wood demand is met by overcutting of the existing forests thus decreasing the sustainable fuel wood supply.

Biomass supply and demand dynamics in 2004

The total fuel wood consumption was 16.8 million tons in 2004-05 and the sustainable supply was only 6.5 million tons which was 39% of the total demand. About 10 million tons (61%) of fuel wood was found deficit in the country. Deficit situation is most severe in Terai region where sustainable supply can only meet about 19% of the total fuel wood demand. Fuel wood demand in the Terai region is very high compared to other regions. The reasons are large population and higher economic activities in these areas. It clearly indicates that the fuel wood requirement in the Terai as well as in other regions are being met by over-cutting of tree resources than its sustainable supply from both forest area as well as from on-farm areas. Hills and

Figure 3.2 Estimation of sustainable

uel wood supply in Nepal

mountain regions were able to meet their demand of

fuel wood by about 57% and 78% respectively. In all three regions, contribution of off-farm areas is quite high in supplying the fuel wood; however their contribution varies greatly from one to another.

Once the supply is found less than its demand then users start to change their strategy in energy resource use. High imbalance situation in Terai region may indicate high use of agricultural residues and animal waste as well as biogas technology.

4. What should we do?

The following table shows the suggested technological interventions in short, medium and long term so that the fuel wood is properly used and substituted by other types of fuels.

These technologies will reduce fuel wood consumption, deforestation and assist effective use of forest wastes and agro-residues besides reducing Green House Gas emissions.

Fuel switching within biomass

S.N. Technological interventions

Short-term

Medium-term

Long-term

1 Improved cooking and heating device

●

2 Gasification technology

● ●

3 Bio-briquettes and briquetting technologies

● ●

4 Biogas ● ● ●

5 Bio-energy power plant

● ●

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E-VISION 2009

As per the energy ladder model, fuel switching consists of three distinct phases. The first phase is characterized by universal reliance on biomass. In the second phase of fuel switching households are hypothesized to move to ‘‘transition’’ fuels such as kerosene, coal, and charcoal in response to higher incomes, urbanization, and biomass scarcity. The third and final phase of fuel switching is characterized by households switching to LPG, natural gas, or electricity for cooking (Heltberg, 2004).

Biomass solid fuels are less efficient than oil, natural gas or propane. It takes larger quantities of wood, agricultural residues to do the job and they will produce larger quantities of smoke when they are burned. That is, solid fuels produce considerably less heat for the amount of fuel consumed and produce significantly more pollution. When we use more efficient s fuels we produce less pollution. This has been described as the energy ladder. The dirtiest fuels such as grass and animal dung are at the bottom. Going up the ladder, step by step with wood, then coal, until the next most efficient type of fuel is used. Producer gas and biogas are dramatically less polluting than solid or liquid fuels. So the use of domestic gasifier or biogas stoves will not only save the fuel wood consumption but also reduce the air pollution since producer gas and biogas are clean fuels.

Improved cooking stoves

The widely used traditional stoves posses disadvantages like low efficiency, produced smoke stays in the kitchen, utensils and clothes are blackened by soot, risk of fire hazards to children and stoves needs blowing regularly. To overcome these demerits of a traditional stove an improved cooking stove has been promoted by the government. The fixed mud improved cooking stove (ICS) has comparatively higher efficiency, produces no smoke in the kitchen, normally no need to blow the fire, minimum risk of fire and burning. But the mud ICS has low space heating efficiency, demands frequent repair and maintenance works like cleaning of chimney every 2-3 months to remove the soot, repairing of baffle inside ICS to maintain the shape and size for efficient operation. There are more than 250,000 ICS installed in the country (AEPC-Nepal, 2008).

The metallic improved stoves can be even used for cooking as well as space heating in the colder region of the country. The portable metallic stove with induced air (air blowers powered by solar energy) has higher thermal efficiency and thus consumes less fuel wood. The metallic stove last long but costs more compared to mud ICS.

Gasifier stoves for cooking, space heating and drying

Gasifier stove can act as a simple and very important device for institutional energy sector which can improve cooking and kitchen environment. It would be more worthy if it is used for roadside hotels, hostels, schools, barracks, etc. where cooking is used for large number of people.

Gas, electricity and liquid fuels being clean and efficient are preferred for cooking, however the access to such energies is limited for majority of population in Nepal, and they are compelled to use wood as fuel in traditional way. Traditional combustion of biomass material produces low conversion efficiency and high emission leading to health problem and deforestation. It is possible to produce gas from wood in practice. Therefore, biomass gasifier has been developed in different parts of the world since nineteenth century. Many countries of the world are working to build institutional type of gasifier for large and continuous cooking purpose. In Nepal, NAST has developed a briquette gasifier stove by adopting the design of Asian Institute of Technology, Thailand. As briquettes are not easily available in rural areas of the country, hence a study was carried out by making modification of that type of gasifier for the purpose of using of other biomass resources. The efficiency of the institutional gasifier was found to be different with different types of fuels; for example for wood chips efficiency of gasifier was found to be 17.84%. Similarly, the efficiency of gasifier for rice husk briquette and maize cob was 19% and 18.9% respectively (Gautam et. al, 2006).

5. Conclusions

ICS has proven to be energy efficient and environment friendly Gasifiers are technically more efficient and environment friendly Gasifiers are more economical to use as institutional cook stove Gasifier should be adapted & promoted to replace traditional dryers Fuel switching within biomass is very important

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E-VISION 2009

Less polluting fuels are difficult to obtain and are costly in general due to processing cost Biomass fuels should be utilized rationally so that supply and demand are balanced Change in cooking behavior is essential to conserve fuel Promote cluster settlement (against dispersed settlement) in hilly and mountainous regions for easy distribution

and conserving fuel and develop horticulture in those areas Plantation of fast growing trees for fuel wood at low altitude to meet the growing demand is essential

Reference:

1. The Beehive Charcoal Briquette Stove in the Khumbu Region, Nepal. Report by: Ing. Sjoerd Nienhuys Senior Renewable Energy Advisor, SNV-Nepal. Report date: Kathmandu, 11 March 2003. Updated Version.

2. Basnyat, M.S, 2004, “A study on gasifier based drying of large cardamom: a case study of Ilam district”, Msc Thesis, Department Of Mechanical Engineering, Tribhuvan University, Nepal.

3. Simkhada, K.P, 2005, M.S, Thesis” A study on the performance of a domestic gasifier stove”, Department Of Mechanical Engineering, Tribhuvan University Nepal.

4. Gautam, J., Chapagain, P., and KC, P., 2006, Study, fabrication and performance evaluation of institutional gasifier stoves, Project Report, Department Of Mechanical Engineering, Tribhuvan University Nepal.

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ISSUES IN NANOSCIENCE AND NANOTECHNOLOGY

Ram Chandra SapkotaAssociate Professor, Department of Mechanical Engineering

Pulchowk Campus, Institute of Engineering, Tribhuvan University

E-VISION 2009

Introduction:Nanoscience can be defined as the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales where properties differ significantly from those at a large scale. It is the study of matter on an ultra-small scale. One nanometer is equal to 10 -9 meter or one billionth of a meter. If we wish to make comparison, the diameter of a human hair is 100 times greater than a nanometer. The spacing between carbon –carbon atoms in a molecule is in the range 0.12-0.15 nm; a pin head is around a million nanometer wide.

In particle sizes of nanoscale, the ratio of surface area to volume is dramatically high. Many important chemical reactions involving catalysts occur at surfaces and it is obvious that very small particles are surprisingly reactive. Because the more is the surface area, the more is the catalyst action to speed up almost all chemical, physical and manufacturing processes .Nanoscience in this respect, has the potential to reshape the world by switching from present manufacturing system to nanotechnology based system.

Nanotechnology refers to a field of applied science where a material is purpose fully controlled at the atomic or molecular level. It also includes the fabrication of devices within the nano scale size range.

Nanotechnology can be seen as an extension of existing science into the nanoscale. It has made possible to produce lighter, stronger and programmable materials that require less energy to produce than conventional materials. It has been also claimed that several nanotechnology based application and processes will bring health as well as environmental benefits to the people and society. Nanotechnology is a diverse collection of fields touching on biology, medicine, materials, computers, manufacturing, physics, chemistry and many other areas. Nanoscale technology and molecular manufacturing are the two broad branches of nanotechnology. Nanoscale technology covers small structures or things from 1 to 100 nanometers in size. Small structures can be used for stronger materials, better medicine, and faster computers.

Molecular manufacturing includes mechanical and chemical manufacturing systems that join molecules together under the control of computers and robots. Chemical manufacturing can be very fast, precise and reliable which will allow automated fabrication of complex products including molecular manufacturing system.

The effect of size on material properties:

Nanotechnology includes the production and application of physical, chemical and biological systems at scales ranging from individual atoms or molecules to submicron dimensions. It also includes the integration of the resulting nanostructure into larger systems. Many physical phenomena become significant when the size of the system decreases. These include statistical mechanical effect as well as quantum mechanical effects. For example, the quantum size effect is the effect where the electronic properties of solids are altered with great reduction in particle size. This effect is not seen at macro to micro level dimensions. But it becomes dominant when the nanometer size range is reached. A number of physical properties change when compared to macroscopic systems. One good example is the increase in surface area to volume of materials. This catalytic activity also opens potential risks in their interaction with biomaterials.

Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macro scale. For example, opaque substances become transparent ,inert materials becomes catalysts , stable materials turn combustible, solids turn into liquids at room temperature ,insulators become conductors. A metal such as gold which is chemically inert at normal scales becomes a catalyst at nanoscale. Materials exhibit these unique quantum and surface phenomena at a nanoscale.

Major issues with nanotechnology:

Nano optimists are claiming that nanotechnology based applications and processes can bring health as well as environmental benefits. These claims are very important and have to be verified and conformed by future research

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E-VISION 2009

and experiment. Researchers and manufacturing industries hope to exploit the unique properties of materials and the processes of nano manufacturing for medical applications and to deliver environmental benefits. Current medical applications of nanotechnologies include anti-microbial wound dressing, and it is anticipated that further applications will include more durable and better prosthetics and new drug delivery mechanisms. Current research into application of nanotechnology includes efforts to reduce the amount of solvents and other harmful chemicals in manufacturing, to improve energy efficiency and energy storage capabilities of materials, and to remove persistent pollutants from soil and water supplies. These improvements can benefits the environmental and increase sustainability of systems and structures.

The potential health and environmental benefits of nanotechnology are appreciable but the changed properties of material at nanoscale which are being exploited by the researchers and industry might have negative health and environmental impacts particularly that they might result in increased toxicity. Some researchers have expressed worries about possible long term side effects associated with medical application. They suspect that nano materials can be biodegradable. For instance, in the case of plastics, they were thought to be the best material but today they have been proved to effect adversely on individuals and the environment.

Nanocritics suggest that there are a number of ways for human to come into contact with nanoparticles. The most obvious is during is during the manufacturing processes of the particles or the products that incorporate them. A second comes from the degradation of products under use. Nanoparticles used to strengthen tires become free from the composite materials as the rubber in the tires is worn out. These particles may become airborne or waterborne and be transmitted to humans and other animal through the ecological system. A third way is through the direct use of the product. For example, nanoparticles in suntan lotions can be spread directly on the body, these small particles will be absorbed through the skin.

Nanoparticles can reach human and other organisms by various environmental routes. Organisms may ingest materials that have entered the water or been deposited on vegetation. The criteria used to identify chemicals that have intrinsic properties that give cause for concern about their potential to damage their environment are based on persistence, bioaccumulation and toxicity.

There is a big social and ethical issues relating to the development of nanotechnology that would benefit from further research and study. These include concerns about who controls nanotechnologies and who will benefit from its exploitation in the short and long term. Although not all these issues are research questions, some are and others may be in the future presenting a unique opportunity for interdisciplinary research to be undertaken between scientists and social scientists. The costs would be small compared with the amount spent on research on nanotechnology, the applications of which could have major social and ethical impacts.

Researcher have pointed out that nanoscience and nanotechnology have huge potential. They have recognized that nanotechnology and its use may create new challenges in the safety, regulatory or ethical domains, which will require societal debate if they are to fulfill this potential. The implementation of their suggestions will address many of the potential, ethical, social, health, environmental, safety and regulatory impacts, and help to ensure that nanotechnology develops in a safe and socially desirable way. It is difficult to predict the applications of nanotechnologies due to the ethical issues and huge social challenges before it. But its advancement can play a big role in enabling a number of applications which may have positive social impacts on the development of material world

References

1. R.sapkota _lecture notes2. Nanoworld.com3. Nanoscience.edu4. Google.com

5. Daenen et al,Eindhoven6. University of technology _wondrous world of

carbon nano tubes

17

Abstract:

The main objective of this paper is to propose an alternative design of a Francis turbine for minimizing the sand erosion effect in sand laden river. To achieve this objective, one erosion model for hydraulic machinery has been selected and all technical and managerial aspects have been considered in this study. Hydraulic turbine components operating in sand-laden water subjected to erosive wear. Erosion reduces efficiency and life of turbine. It also causes problem in operation & maintenance. Himalayan rivers carry large amount of hard abrasive particles. Withdrawal of the clean water from the river for power production is expensive due to design, construction and operation of sediment settling basins. Even with the settling basins, 100% removal of fine sediments is impossible and uneconomical. The design of the Francis turbine can be done in two main stages. The first step is the initial design, based on empirical data and the Euler’s turbine equation. The second step is a three dimensional CFD analysis for fine tuning of the design, normally based on the assumption of uniform flow field from the guide vanes cascade towards the runner blade inlets. The hydraulic design strategy for the Francis turbine has played the major role in the design. The main objectives in the design of the medium head Francis turbines are to reduce the pressure pulsation, avoid cavitations, to reduce sand erosion and to gain maximum efficiency. The ideal goal is to design a runner that has the widest possible operating range for head variations beyond the normal design head, and that would require the minimal maintenance. The initial step is the most important. The basic hydraulic design of the runner is done during this stage, and the balancing of the pressure distribution on the blades by controlled parameters gives the designer an important feeling, which assists in evaluating the result of the CFD analysis. This feeling is very useful in helping to make the right changes in the geometry and to improve the performance of the runner. The CFD analysis is also important in the study of the model turbine behavior and forms the basis for final tuning of the prototype Francis runners.

Key words: Francis turbine, erosion, efficiency

ALTERNATIVE APPROACH FOR DESIGNING A FRANCIS TURBINE FOR SAND LADEN WATER

Hari Prasad Neopane 1), Ole Gunnar Dahlhaug 2) and Tri Ratna Bajracharya 3)

1. Department of Energy and Process Engineering, Norwegian University of Science & Technology, Norway

2. Department of Energy and Process Engineering, Norwegian University of Science & Technology, Norway

3. Department of Mechanical Engineering, Tribhuvan University, Institute of Engineering, Kathmandu, Nepal

E-mail: [email protected], [email protected], [email protected]

E-VISION 2009

1. Background

Erosion of turbine components is one of the major problems in run off river type hydropower plant. Erosion of turbine may be caused by several reasons, such as abrasive and erosive nature of silt particles contained in the streams.

Sand erosion is designated as abrasive wear. This type of wear will break down the oxide layer on the flow guiding surfaces and partly makes the surfaces uneven which may also be the origin for cavitation erosion. Sand erosion therefore may be both a

releasing and contributing cause for damages which are observed in power plants with a large transport of wearing contaminants in the water flow. The erosion damages are to some extent different for Pelton and Francis turbines. On Pelton turbines it is the needle tip, the sealing rings in the nozzles and the runner buckets which are most exposed to sand erosion. The wear on needle tips occurs as streaks and indentations forward to the tip. On the

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E-VISION 2009

buckets the sand contaminants in the water flow is wearing the bucket gap backwards. That causes a delayed contact with the jet and makes an erroneous splitter. The bucket edge is usually exposed to an even wear and tear and becomes wider, and extended indentations may occur just behind the edge [1]. Mass loss is one of the indictors of erosion of turbines. There are number of cases in this. For example, significant amount of erosion had appeared in turbine bucket and needle in first year of operation (about 6000 hours) in Khimti I hydropower plant [2].High head Pelton and Francis turbines are affected by sand erosion, the erosion of Kaplan turbines are also reported [3]. The efficiency of the turbine decreases with the turbine erosion. Pelton turbine has maximum drop in efficiency at full load where as in Francis turbine; maximum drop is a part load. One of the factors causing loss of efficiency in Francis turbine is the increase in guide vane clearance. The effect of the faceplate wear was investigated by Brekke in the Driva Power Plant (71.5 MW, Hn=540 m, n=66 rpm) in Norway. About 4% relative efficiency increments were observed at Best Efficiency Point after the repair of faceplate. The thermodynamic efficiency test at Kvilldal Power Plant in Norway (315 MW, Hn=520 m, n=333 rpm) by inserting 1 mm shim in the guide vane shaft (making artificial gap between faceplate and guide vane) showed the difference in 0.8% relative efficiency at BEP [4]. A clear understanding of relationship between sediment concentration, sand erosion and efficiency helps for the optimization of power plant operation and maintenance.If the sediment particle contains high value of quartz, erosion rate is rapid [5]. Mineral content analysis of the water sample from the Chilime River, Nepal shows that the quartz content is greater than 75%. Quartz is a very hard particle having Mohr’s hardness scale with value 7. It causes abrasion erosion in the hydraulic machinery when they strike with very high velocity [6]. Quartz content in the sediment is greater than 60% in most of the Nepalese rivers [7]. The Fig. 1.1 gives overview of quartz content in different rivers of Nepal.

2. Conventional Design of Francis Turbine

2.1 The importance of the Runner: draulic energy of the water is converted into mechanical shaft energy in the turbine runner at the expense of the interaction between flow and the runner blades constituting a rotating cascade of profiles. Runner is one of the most important components of the turbines. Francis turbine is a reaction type of turbine where the specific energy in front of the runner consists of partly pressure energy and partly kinetic energy. For the high head type of the Francis turbine approximately 50% of the energy is converted into kinetic energy in front of the runner and there is a pressure drop through the runner of approximately 50% of the total energy drop through the turbine. So, the design of the runner is very important.

2.2 Input Parameter:

19Fig. 1.1 Quartz Content In Nepali Rivers

Qu

atrz

con

ten

t [%

]

0

1020

30

40

5060

70

80

Wes

t Set

i

Jhim

ruk

Rap

tiK

hol

a

Mad

iRev

erG

anah

a

Aru

nK

hol

a

Mod

i-2M

odi-

1

Aad

hiK

hol

aT

inau

Ku

lek

han

i

Ch

itla

ng

Pal

un

g

Bag

mat

i

Man

ahar

aD

hob

i

Gau

r

Ros

hi

Dh

adK

hol

a

Kh

imti

Kh

imti

Kh

ola

Tam

ak

osh

i

Ph

edi

Dol

alG

hat

Su

nk

osh

i

Sap

taK

osh

i

Kar

nal

i

West Rapti

Gandaki

Tin

au Bagmati Bagmati

Kathmandu

Koshi

Ref. Kathmandu University, & IOE

Ch

ilim

e

E-VISION 2009

Before going to start the design of the Francis runner there should be input parameters. The main input parameter of the design is the net head (He) which is calculated from the available head after deducting the friction losses on the penstock, flow at the full load (Q) and available submersion. The available submersion is the distance between the centerline of the turbine and the tailrace. For the purpose of this research work, the input parameters have been selected based upon the 12 MW Jhimruk Hydro Power plant which is located in western part of Nepal. The input parameters are:

Flow at the full load (Q) = 7.05 m3/s Net head (Hn) = 201.5 m Available submersion = 0 m

2.3 Calculations of the Dimensions of the Runner:

The development of hydraulic turbines is aimed towards two goals: to achieve the maximum efficiency and to avoid cavitation damage with the highest possible circumferential speed and meridional velocity in the runner for the given submergence of the turbine.

Fig.2.1 Main dimension of the runner

For high head runners the cavitation problems are most likely to occur at the outlet section of the blades. In order to study the cavitation a careful study of the blade loading must be done. For such study, the curvature of shroud and crown as well as curvature of the blades, the blade angles and the blade leaning are the important parameters.

The empirical relation for the outlet angle and peripheral velocity is given by [8]:

130 < 2 < 220 lowest values for the highest head

35 < U2< 43 highest values for the highest head

For maximum efficiency, maximum peripheral speed at the outlet of the runner, U2 = 40m/s at the ring for moderate setting assumed. In some case, the noise and vibrations problems are likely to increase with the speed. To avoid the noise and vibrations problem, higher values of peripheral velocity couldn’t be used. U2 >43 m/s is not recommended.

If the higher values of is chosen the blade outlet angle should be reduced. Assume, = 170. The lower values

of is also not recommended due to welding constraints. From the maximum efficiency point of view, no swirl at the outlet i.e. C2u= 0 m/s has been selected.

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The meridional velocity at the outlet of the runner at best efficiency with no rotation in draft tube will get a normal value in this case. (See the outlet velocity vector diagram)

Then the following meridional velocity will be obtained:

m/s (2.1)

Fig.2.2 Outlet velocity diagram

The ratio between the full load flow and the best efficiency flow

[ - ] (2.2)

We choose

So, = 5.875 m3/s, (* denotes the best efficiency point)

The outlet diameter may now be found by assuming to be constant across the outlet area across the runner outlet diameter:

(2.3)

The speed of the turbine will then be according to the chosen values of and

(2.4)

This will not normally be a synchronous speed and an adjustment of the speed has to be made by adjusting the circumferential speed U2 and the diameter. We want to keep the velocity triangle the same at the outlet therefore the outlet blade angle 2 is constant.

In order not to increase the necessary submergence of the turbine, the speed should be reduced to nearest synchronous speed.

The synchronous speed is found by checking the formula

21

222 RU

C2=

Cm

2

V r2

2

222 RU

C2=

Cm

2

V r2

2

E-VISION 2009

[rpm] (2.5)

Where Z=number of the pairs of the poles in the generator for an electric grid with a frequency of 50 Hz.

If Z= 3, then and = 104.71 rad/sIf Z = 4, then and = 78.53 rad/s

Using an empirical equation for calculation of the Net Positive Suction Head [4],

[m] (2.6)

Where a and b are constant and depends upon the speed number

[ - ] (2.7)

If then

If then

for for

In both case < 0.55 and thus and

If the outlet angle shall be unchanged as well as the best efficiency flow Q* the velocity vector diagram will be homogeneous and the following equation will be valid.

[m3/s] (2.8)

[m/s] (2.9)

Then from simplification of above (2.8) and (2.9) equations we get

[m] (2.10)

For determining the required submergence of the runner the following equation has been used [5],

[m] (2.11)

NPSH is depends on turbine parameters. It is also a requirement for the turbine design and has been denoted as a required net positive suction head for turbine. The NPSH of the power plant has been included the necessary submergence of the runner (-hs) the barometric pressure (hb) and the vapor pressure (hva) which ultimately depends upon the water temperature.

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The practical experience shows that for not exceed the cavitation limits, the difference of the barometric pressure and the vapor pressure in the above equation is around -10 m. then the above equation becomes,

[m] (2.12)

Before going to choose the best synchronous speed of the runner we have to calculates the outlet diameter, outlet peripheral velocity of the runner and required submergence by changing the outlet blade angles as shown in the following tabular form,

n = 1000 rpm

2 D2 U2 hs

15 0.81 42.41 -2.42

16 0.79 41.5 -2.89

17 0.77 40.31 -3.21

n = 750 rpm

2 D2 U2 hs

15 0.89 34.95 1.58

16 0.87 34.16 1.26

17 0.85 33.5 0.94

From the above result we can choose the best parameter of the outlet of the runner. The selection of the parameters depends upon the fulfillment of the main objective of the Francis runner, which have been defined in the beginning. So the best outlet parameters and appropriate speed of the runner are as follows:

2 = 170 D2 = 0.85 m U2 = 33.5 m/s Cm2 = 12.2 m/s n = 750 rpm.

The inlet dimensions may now be found by means of the Euler turbine equation. The energy converted by the runner will be

[m2/s2] (2.13)

The hydraulic efficiency is the ratio of the available energy which is transfer to and converted to mechanical energy by the runner and the net energy drop from the upstream to down stream side of the turbine. (Mechanical losses, friction losses and leakage losses are not taken into consideration in the hydraulic efficiency.) That is:

[ - ] (2.14)

Principally every turbine is designed according to the available discharge Q, net head H n and a chosen optimal rotational speed n. These parameters however, differ over wide ranges from one site to the other. For this variability it is very useful to have similarity relations at hand for comparison means. In the following it is therefore, introduced some ratio parameters which are designated as reduced quantities.

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as reduced absolute velocity [ - ] (2.15)

as reduced peripheral velocity [ - ]

(2.16)

as reduced relative velocity [ - ] (2.17)

Velocity diagrams based on dimensional values of the velocities are valid for only one single value of the net head Hn. If reduced velocities however, present the corresponding velocity diagrams, these diagrams keep a similar shape. The velocity diagrams based on reduced velocities are therefore beneficial because these diagrams are valid for any value of Hn.

Additional useful reduced quantities are:

is the reduced head [ - ] (2.18)

is the reduced discharge [ - ] (2.19)

is the reduced angular velocity [ - ] (2.20)

By using dimensionless reduced parameters the above equation yields

[ - ] (2.21)

Assume that the hydraulic efficiency of 96% and the approximately 50% of the energy in front of the runner is converted to kinetic energy.

i.e.

[ - ]

By drawing the inlet velocity vector diagram, will try to obtain the stagnation point on the blade inlet tip and the inlet angle so the relative velocity does not lead to separation and possible inlet cavitations. (Especially for low head turbines)

Fig. 2.3.The inlet velocity diagram

24

1

Cu1 U1

Cm

1 r1

E-VISION 2009

Besides the assumption that .Now will use eq.(2.21) when assume the hydraulic efficiency of the runner to be 96% and no swirl conditions at the outlet of the runner. The following equation yields:

[ - ] (2.22)

The inlet velocity diagram clearly illustrates that the smallest variation of the inlet flow angle with variation in the guide vane angle is obtained if the angle between the absolute and relative velocity in close to 90 0 at best efficiency point of operation.

Using the following empirical relation for calculation of the reduced dimensionless circumferential speed of the blade inlet [8]

[ - ] (2.23)

The reduced dimensionless circumferential speed of the blade inlet then from experience may be chosen to 0.71, for a low specific speed and then

[ - ] (2.24)

The inlet diameter of the runner can now be found by the absolute value of U1

[m/s] (2.25)

The inlet diameter of the runner will then be

[m/s] (2.26)

The meridional velocity at the inlet may from experience be chosen approximately 10% [8] lower than at the outlet of the runner in order to obtain a slight acceleration of the meridional flow. (However, this choice will be different for different manufacturers due to the philosophy of blade shape etc,)

Thus, [m/s] (2.27)

Then the height of the blade at the inlet =B1, can now be found by means of equation of continuity as follows,

[m] (2.28)

The inlet blade angle = 1 can be found from the following relation (see the above inlet velocity triangle)

[degrees] (2.29)

Note: In this preliminary calculation the displacement of the blade thickness has been neglected. By taken the blade thickness into consideration the blade angles must be corrected due to increased relative velocity or meridional velocity.

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E-VISION 2009

3. Erosion Models And Alternate Design of Runner

The mathematical models of erosion are useful for design of turbine components, sediment settling basin and optimization of hydropower plant operation in Sand-laden River. Most often, individual particle dynamics are used for developing erosion models. Empirical and statistical relations are also often developed from experiments and field experiences. As erosion studies are heading toward numerical modeling and simulations, the importance of analytical models are increasing day by day. Truscott [6] has found that the most often quoted expression for erosion is

(3.1)

3.1 Erosion Models for Hydraulic Machinery

The erosion models are basically developed for specific purpose or condition. For example, Bitter's model is developed for dry condition, hence it is not clear whether this equation realistically predict erosion rate for wet condition or not. Few researchers have presented models specifically for hydraulic machinery. Truscott [9] presented the equation of Bergeron (in 1952) to predict the erosion rate of pump with simplified assumptions such as pure sliding of spherical particles over the surface. He presented equation for erosion as:

(3.2)

Where Vchar is the characteristic velocity of liquid, D is the characteristic dimension of the machine, ρp is density of particle, Dp is diameter of particle, p is number of particles per unit surface area, ρ is density of liquid and K is experimental coefficient depending upon nature of abrasive particles. This equation is proportional to experimental coefficient, which is dependent on abrasive nature of particles.

Karelin et al. [10] established the equation for surface erosion based on impact effect of particles considering kinetic energy of single particle.

They have anticipated deviation on erosion estimated by equation due to uncertainties like non-homogeneous particles, variable concentration, continuous alteration and pulsation of velocities and pressure, non-uniform flow distribution and so on. On the contrary to laboratory tests, Tsuguo [11] established the relationship of factors concerning erosion of turbines based on 8 years erosion data of 18 hydropower plants. The repair cycle of turbine is determined according to calculation of turbine erosion from equation, which gives erosion rate in term of loss of thickness per unit time.

(3.3)

Where λ is turbine coefficient at eroded part; c is the concentration of suspended sediment, V is relative velocity. The term f is average grain size coefficient on the basis of unit value for grain size 0.05 mm. The terms k1 and k2 are shape and hardness coefficient of sand particles and k3 is abrasion resistant coefficient of material. The x, y and n are exponent values for concentration, size coefficient and velocity respectively. The value of x and y are close to the unity and any deviation of this linear proportionality is determined from plot of wear versus parameter. The values of n are proposed for different turbine components based on relation between relative velocity and erosion. Minimum value of n is proposed as 1.5 for Pelton bucket and maximum value is 3 for Francis turbine runner. Equation 3.3 has been chosen for calculation of outlet dimensions of modify turbine runner.

As, and also assume all the coefficients in equation 2.3 has a constant values,

26

Table 4.1 Variable input parameters

E-VISION 2009

So, (3.4)

Where [ - ]

For the discussion, the constant, k1 is chosen to be 0.3.

4. Results and Discussion

The main erosion of the Francis turbine occurs at the outlet of the guide vanes and at the outlet of the runner. In order to reduce the erosion rate of the turbine, the absolute velocity at the inlet of the runner and the relative velocity at the outlet of the runner have to be reduced. In this study, the flow and head are kept constant while the speed, inlet

peripheral velocity and outlet runner blade angle has been changed according to Table 4.1

The results show that the outlet diameter changes relatively little while the inlet diameter changes drastically. The reduction of the erosion at the outlet is more than at the inlet. This is shown in Fig. 4.1

Figure 4.1 Results from the new design of the Francis runner

The inlet angle of the turbine has changed so that the design looks more like a pump-turbine. This means that the turbine will be larger than the traditional design. The reduction of the erosion is linked to the reduction of the

27

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

750 600 500 433 375 333 300 275

Speed [rpm]

Dia

mete

r [m

]

0

10

20

30

40

50

60

70

80

90

100

Ero

sion R

educt

ion [%

]Outlet Diamater

Inlet Diameter

Erosion reduction at the outlet

Erosion reduction at the inlet

Speed rpm n 750 600 500 433 375 333 300 275

Inlet peripheral velocity, reduced - u1 0,71 0,74 0,77 0,8 0,83 0,86 0,89 0,92

Outlet blade angle degrees 2 17 19 21 23 25 27 29 31

E-VISION 2009

velocity and therefore the size of the turbine increases. This result in a higher price of the turbine, but it will reduce the maintenance costs during its lifetime.

It has been shown from the above calculation that the design of the runner can decrease the sand erosion. If a Francis turbine designer combines the hydraulic design and coating of the critical parts, a significant reduction of erosion can be achieved.

5. ConclusionsThe modification in the conventional design of runner has played significant role for increasing manufacturing cost, reducing repair and

maintenances cost and increase the life and efficiency of the runner. Hence details technical, managerial and economical consideration will be needed along with experimental and computational fluid dynamics analysis.

6. References

[1] T. R. Bajracharya, C. B. Joshi, R. P. Saini and O. G. Dahlhaug, Efficiency improvement of hydro turbines through erosion resistant design approach, ICPS Conference Proceedings (2004), IOE/TU/IITB/IIIE

[2] T. R. Bajracharya, C. B. Joshi, R. P. Saini, O. G. Dahlhaug, Sand erosion of Pelton nozzles and buckets: A case study of Chilime Hydropower Plant, Wear (2007) doi: 10.1016/j.wear.2007.02.021

[3] B. S. Mann, High-energy particle impact water resistance of hard coating and their application in hydro turbines, Wear (2000), 140-146

[4] B. Thapa, Ole G. Dahlhaug, Sand erosion in hydraulic turbines and wear rate measurement of turbine materials, CD ROM proceedings of international Conference-Hydro Africa 2003

[5] T. R. Bajracharya T. R., D. Sapkota, R. Thapa, S. Poudel, C. B. Joshi, R. P. Saini, O. G. Dahlhaug (2006), Correlation Study on Sand Led Erosion of Buckets and Efficiency Losses in High Head Power Plants, Proceedings of First National Conference on Renewable Energy Technology for Rural Development 12-14 th

October Kathmandu, Nepal.

[6] B. Acharya, B. Karki, and L. Lohia, (2005), Study on the Sand Erosion Led Damages of the Pelton Turbine Component and their effects (A Case Study of Chilime Hydroelectric Project), BE Thesis, Department of Mechanical Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University

[7] B. Thapa, R. Shrestha, P. Dhakal, (2004) Sediment in Nepalese hydropower projects, Proc, Int. Conf. on the great Himalayas: climate, health, ecology, management and conservation, Kathmandu

[8] H. Brekke: Hydraulic Turbines, Design, Erection and Operation, NTNU, Trondheim, 2000. [9] G. F. Truscott, A literature survey on abrasive wear in hydraulic machinery, Wear (20), Elsevier (1972) pp 29-

49

[10] V. Y. Karelin, Fundamentals of hydro-abrasive erosion theory, Imperial College press (2002) pp 1-52

[11] N. Tsuguo, Estimation of repair cycle of turbine due to abrasion caused by suspended sand and determination of desiting basin capacity, Proceedings of International seminar on sediment handling techniques, NHA, Kathmandu (1999)

28

List of Symbols and AbbreviationsList of Symbols and Abbreviations

ELECTROCHEMICAL MICRO MACHINING (EMM):A PROMISING FUTURE TECHNIQUE

Er. Luza ShresthaLecturer, Department of Mechanical Engineering Pulchowk

Campus, Institute of Engineering, Tribhuvan University

E-VISION 2009

Guide vane blade angle degrees k3 Abrasion resistance coefficient -

a Constant (used in equation 1.6) - Experimental coefficient -

A Cross sectional area of pipe m2 Turbine coefficient -

b Constant (used in equation 1.6) - Capacity ratio -

B Height of the runner m n Speed rpm

Blade angle degrees NPSH Net Positive Suction Head m

c Concentration of the sediments ppm Angular velocity rad/s

C Absolute velocity at the inlet m/s Angular velocity, reduced value -

CAbsolute velocity, reduced value

- Speed number -

D Diameter m p Number of particles 1/m2

E Energy m2/s2 Density kg/m3

h hydraulic efficiency - Q Flow rate m3/s

f Grain size coefficient - Q Flow rate, reduced value -

g Gravity m/s2 U Peripheral velocity m/s

H Head m U Peripheral velocity, reduced value -

h Head m V Relative velocity m/sh Head, reduced value - V Relative velocity, reduced value -

Hn Net head m Vchar Characteristic velocity m/s

k1 Shape constant - Z Number of generator pole pairs -

k2 Hardness constant - W Erosion rate -

Sub Symbols:

b Refers to the atmospheric pressure s Refers to the suction head

h Hydraulic x Concentration exponent

m Refers to the meridional direction y Size exponent

n Refers to the net value z Characteristic velocity exponent

p Refers to a particle 0 Refers to the centerline of the stay vane shaft

u Refers to the peripheral direction 1 Refers to the inlet of the turbine runner

va Refers to the vapor pressure 2 Refers to the outlet of the turbine runner

r Relative value * Refers to the best efficiency point of the turbine

o Refers to the full load of the turbine

29

E-VISION 2009

Introduction

The needs for miniaturization of various ultra precision items utilized for producing highly precision machines and equipments necessitate the development of manufacturing processes capable of performing micro manufacturing activities. The term micro machining refers to material removal of small dimensions that range from several microns to millimeters. Since miniaturization will continue as long as people require efficient space utilization and more efficient and better quality products, micro machining technology will become still more important in the future[1].

Advanced micro machining may consist of various ultra precision machining activities to be performed on very small and thin work pieces [2]. Small and micro – holes, slots and complex surfaces are needed to be produced in large numbers, sometimes in a single work piece, especially in the electronic and computer industries. When conventional machining techniques are employed, the problems usually encountered are high tool wear rate and heat generation at the tool and work piece interface and subsequent alteration of the work piece material characteristics, etc. [3].Rigidity requirements for the tool are another major problem in conventional machining of small and deep holes, complex surface or shapes. In addition, it becomes troublesome to machine three dimensional shapes [4].

Non conventional machining processes are getting their importance due to some of these specific advantages. Electro chemical machining (ECM) was introduced in the late 1950s and early 1960s in aerospace and other heavy industries for shaping and finishing operations. All of these processes now play an important role in the manufacturing of a variety of parts ranging from machining of large metallic pieces of complicated shapes to opening of windows in silicon that are a few microns in diameter[5]. When this electrochemical machining process is applied to micro machining range for manufacturing ultra precision shapes, it is called electrochemical micro machining (EMM) [6].

Need of Electrochemical Micro Machining

Recent changes in demand from society have forced the introduction of more and more micro parts in various types of industrial products. For example, in the case of fuel injection nozzles for automobiles, several regulations arising from environmental problems have forced manufacturers to improve their design, making them smaller and more compact, with high accuracy. Inspection of the internal organs of the human body and surgery without pain are universally desired. Miniaturization of medical tools is an effective approach to arrive at this target. Micro-machining technology plays an increasingly decisive role in the miniaturization of components ranging from biomedical applications to chemical micro-reactors and sensors. Micro-machining is the key technology in micro-electromechanical systems (MEMS).

A general comparison between ECM and EMM is presented in Table 1 [8].

Major machining characteristics

Electrochemical machining

Electrochemical micro – machining (EMM)

Voltage 10 – 30 V <10 V

Current 150 – 10000 A < 1 A

Current density 20 – 200 A/cm2 75 – 100 A/cm2

Power supply – DC Continuous/ pulsed Pulsed

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E-VISION 2009

Frequency Hz – kHz range kHz – M Hz range

Electrolyte flow 10 – 60 m/s < 3 m/s

Electrolyte type Salt solution Natural salt or dilute acid/ alkaline solution

Electrolyte temperature 24 – 65 º C 37 – 50 º c

Electrolyte concentration > 20 g/l < 20 g/l

Size of the tool Large to medium Micro

Inter – electrode gap 100 – 600 μm 5 – 50 μm

Operation Maskless Mask/ maskless

Machining rate 0.2 – 10 mm/min 5 μm/min

Side gap > 20 μm < 10 μm

Accuracy ± 0.1 mm ± 0.02 – 0.1 mm

Surface finish Good, 0.1 – 1.5 μm Excellent, 0.05 – 0.4 μm

Problems due to waste disposal/toxicity

Low Low to moderate

Table 1: General comparison between ECM and EMM

ECM machining techniques do not produce thermal or mechanical stresses on the work piece material and they have versatility that they can machine any kind of material. They leave no heat affected layer and produce no tool wear. The machining performance in ECM is governed by the anodic behavior of the work piece material in a given electrolyte. EMM appears to be a very promising micro – machining technology due to its advantages which include high MRR, better precision and control, short machining time, reliability, process flexibility and environmental acceptability, and it also permits the machining of chemical resistant materials like titanium, copper alloys and stainless steel which are widely used in bio medical, electronic and MEMS applications.

Material Removal and Machining Accuracy in EMM

In the machining region where the workpiece directly faces the cathode tool, the anodic reaction rate is constant for a constant inter-electrode gap (IEG) and electrolyte conductivity. The machining performance is influenced by various predominant process parameters, such as current density, IEG, electrolyte flow rate, concentration and type of electrolyte, and also the anode reactions [9, 10]. Material removal is maximum for small IEG. Experimental results have proved that the addition of a magnetic field causes increase in material removal rate and accuracy.

In EMM, the machining performance is influenced significantly by the current density and the anodic reaction. The metal removal rate (MRR) at any location is proportional to the product of current density (J) and metal dissolution efficiency. Shape prediction of ECM, therefore requires knowledge of not only the current distribution but also the functional dependence of metal dissolution efficiency (η) on current density and electrolytic flow condition.

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Fig. 1 SEM micrograph of a 3D electronic circuit board component [8]

E-VISION 2009

Material removal rate (MRR) r = J a η/ ν F ρ

Where a is molecular weight of the metal, ν is the valence of metal dissolution, F is Faraday’s constant and ρ is the density of metal (gm/ cm3)

Machining accuracy can be influenced by power supply, electrolyte selection and flow, selection of tool, IEG, UR (Unit Removal) etc. For achieving higher accuracy, pulsed power supply with small IEG, passivating electrolyte, balance electrode and dual pole tool are preferred, but the selection of all machining parameters depends on the shape of the final product [11]. Temperature of the electrolyte will also influence the machining accuracy and surface finish in EMM

Applications

Research and development in the area of EMM will be important and will fulfill the various urgent needs of the electronics and precision industry in the area of ultra precision micro fabrication. Some of the application fields of EMM are

Surface finishing of print bands:

The print bands used in high-speed impact printers are fabricated from sheets of hardened ferrite stainless steel. The print band system consists of a group of formed characters. Precise location of all the characters on a band is achieved through timing marks. The characters and timing marks on the print bands must have special characteristics to meet the desired trade-off between ribbon life and print quality. Bands with round-edged characters increase ribbon life. To provide a high degree of character rounding, the EMM should involve a high rate of dissolution. Surface finishing of print bands is most important in the print band manufacturing process. An electro polishing process has been developed which gives micro-smooth surfaces for print bands. Fig. 6 shows a print band (a) before finishing and (b) after electro polishing and character rounding. Electro - polishing gives better surface finish and higher throughput. A wide range of metals can be used for print bands through the use of electro polishing technology [7].

Nozzle plate for ink-jet printer head:

Electroformed nozzles are currently used in a number of commercially produced ink-jet printers. Electroformed nozzles are produced by plating nickel on to a mandrel (mold), which defines the pattern of the nozzle, and then removing the finished product [12]. Pulsating current/voltage permits better control over EMM of thin films and foils for applications in micro fabrication. Through-mask EMM was used to fabricate a series of flat-bottomed conical nozzles in a metal foil. The process is applicable to various materials including high strength corrosion resistant materials such as conducting ceramics [13 and 14]. The final shape of the nozzle depends on dissolution time and conditions. Pulsed current can improve the accuracy of finish of the nozzles.

Deburring:

The ECM method is widely used for removing burrs left by other operations. ECM is a useful method for

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deburring such products, since it can meet the increasing requirements for accuracy of dimension and form [5 and 6]. Electrochemical deburring is very rapid, with virtually no damage to the workpiece.

Production of high accuracy holes:

EMM can be used for the accurate production of holes [6]. A typical application is the production of micro-holes in turbine blades for generating a cooling effect, where EMM’s advantages are fully exploited, including its applicability regardless of material hardness for generating complex geometry, high surface quality with stress and burr free surfaces and economic large scale production. It also produces many parts for aerospace and aircraft applications, like rocket engine parts, and jet engine rings more efficiently.

It has also found many applications in other industries, like the automobile, medical and defense industries. The production of artificial hip joints of titanium and cobalt alloys and valve parts are now established industrial processes. It has also been used to produce micro grooves for self-acting fluid film bearings, which can be controlled precisely without distorting the other surfaces.

3D micro-machining: 3D EMM is shown in Fig. 1, an SEM micrograph of a machined component of an electronic circuit board in which a platinum wire of 10 μm diameter was used as a tool on a copper sheet with the application of 50 ns, 1.6 V pulses of 2 MHz frequency, to obtain a delicate 3D copper structure, i.e. 5 μm×10 μm×12 μm in the middle of a hole on a base, i.e. 15 μm×15 μm×10 μm. The micro tool was first fed vertically 12 μm deep into the workpiece. After this vertical machining, the micro tool is moved laterally along the prescribed path in the copper sheet. The outer rectangular trough was dissolved to a dimension of 22 μm×14 μm. During the process, the micro tool feed rate was adjusted to 0.5 μm by monitoring the peak current transient of the inter-electrode gap.

Conclusions

The micro-ECM (EMM) method can be effectively used for high precision machining operations such as removal of burrs, making patterns in foils, and 3D micro-machining, and also in various applications. Results of recent research indicate that the applications of Electrochemical metal removal in micro-machining offer many opportunities that have been unexplored till now. Further research into EMM will open up many challenging possibilities for effective utilization of ECM in the micro-machining domain. The increasing demands for precision manufacturing of micro parts for biomedical components, automotive components and IT applications will lead modern manufacturing engineers to utilizing EMM technique more successfully considering its advantages, i.e. quality, productivity and ultimately cost efficiency, which are still vital for success in a competitive environment.

References

[1] N. Tenigyahi, Current status in and future trends of ultra precision machining and ultra fine material processing Annals of the CIRP 2 2 (1983), pp. 573–582. [2] T. Norio - Ann. CIRP 2(2) 1983, 573 [3] T. Masuzava and H.K. Tonshoff, Three-dimensional micromachining by machine tools Annals of the CIRP 46 2 (1997), pp. 621–628 [4] B. Bhattacharyya, S. Mitra and A.K. Boro, Electrochemical machining: new possibilities for micromachining. Robotics and Computer Integrated Manufacturing 18 (2002), pp. 283–289. [5] C. Van Osenbrugger and C. de Regt, Electrochemical micromachining. Philips Technical Review 42 (1985), pp. 22–32. [6] M. Datta and L.T. Romankiw, Applications of chemical and electrochemical micromachining in the electronic industry Journal of the Electrochemical Society 136 (1989), p. 285c [7] M. Datta and D. Landolt, Fundamental aspects and applications electrochemical micro fabrication Electrochimica Acta 45 (2000), pp. 2535–2558 [8] B. Bhattacharyya, J. Munda, M. Malapati; Advancement in electrochemical micro – machining, International Journal of Machine Tools and Manufacture 44 (2004) 1577 - 1589

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[9] N. Tenigyahi, Current status in and future trends of ultra precision machining and ultra fine material processing Annals of the CIRP 2 (2) (1983), pp. 573–582. [10] B. Bhattacharyya and S.K. Sorkhel, Investigation for controlled electrochemical machining through response surface methodology-based approach. International Journal of Materials Processing Technology 86 (1999), pp. 200–207 [11] S.H. Ahn, S.H. Ryu, D.K. Choi and C.N. Chu, Electrochemical micro drilling using ultra short pulses Precision Engineering 28 2 (2004), pp. 129–134. [12] M. Datta, Fabrication of an array of precision nozzles by through-mask electrochemical micromachining. Journal of the Electrochemical Society 142 11 (1995), pp. 3801–3805. [13] A.C. West, C. Madore, M. Matlezz and D. Landolt, Shape changes during through mask electrochemical micromachining of thin metal films. Journal of the Electrochemical Society 139 2 (1992), pp. 499–506. [14] R.V. Shenoy and M. Datta, Effect of mask wall angle on shape evolution during through mask electrochemical micromachining. Journal of the Electrochemical Society 143 2 (1996), pp. 544–549.

34

WASTE WATER TREATMENT IN NEPAL

* Ajay Kumar Jha, **Nawraj Bhattarai *Department of Municipal and Environmental Engineering

Harbin Institute of Technology, Harbin, China**Lecturer, Department of Mechanical Engineering

Institute of Engineering, Tribhuvan University, Nepal

E-VISION 2009

Abstract

The existing treatment plants and sewerage systems face number of problems in Nepal. In most cases, treatment systems are not functioning, or operating at far below the capacity. In addition, many towns of the country are unable to operate schemes in a financially viable manner. The increasing trend of construction of sewers by municipal authorities without considering treatment facilities is posing serious threats to the environment. All industrial wastewater in most cases are directly discharged into local water bodies without proper treatment. So far rivers and streams in the Kathmandu valley receive raw domestic sewages and untreated industrial wastes. In this context, the present paper presents about the development trend of wastewater treatment plants in the world and status of existing plants in Nepal.

Keywords: Waste water treatment, Financially viable, Sewage system

1. Introduction

1.1 Waste WaterWastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. Sewage is correctly the subset of wastewater that is contaminated with feces or urine. "Sewage" includes domestic, municipal, or industrial liquid waste products.

1.2 Waste water treatmentAs the name implies, Waste water is mostly water; a very small portion is waste material. What happens in a wastewater treatment plant is essentially the same as what occurs naturally in a lake or stream. The function of a wastewater treatment plant is to speed up the process by which water cleanses (purifies) itself. A treatment plant uses a series of treatment stages to clean up the water so that it may be safely released into a lake, river, or stream. Major steps are:

1.2.1 Primary Treatment

In primary treatment, sand, grit, and the larger solids in the wastewater are separated from the liquid. Screens, grit chamber and settling tanks are most commonly used for the separation. Primary treatment removes 45 to 50 percent of the pollutants.

1.2.2 Secondary Treatment

After primary treatment, wastewater still contains solid materials either floating on the surface, dissolved in the water, or both. Under natural conditions, these substances would provide food for such organisms as fungi, algae, and bacteria that live in a stream or lake. In this process, wastewater is separated from the organisms and solids,

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disinfected to kill any remaining harmful bacteria, and released to a nearby lake, river, or stream. Secondary treatment is largely a biological process and microorganisms convert non settle able solids to settle able solids. It removes the pollutants--up to 85 or 90 percent altogether.

1.2.3 Tertiary Treatment

After primary and secondary treatment, municipal wastewater is usually disinfected using chlorine (or other disinfecting compounds, or occasionally ozone or ultraviolet light). An increasing number of wastewater facilities also employ tertiary treatment, often using advanced treatment methods. Tertiary treatment may include processes to remove nutrients such as nitrogen and phosphorus, and carbon adsorption to remove chemicals.

1.2.3 The Stuff that’s Left Behind

Sludge requires proper treatment and disposal, and can often be reused. Sludge handling methods are designed to destroy harmful organisms and remove water. The end product of the sludge handling process is a relatively dry material known as “cake.” It can be applied to agricultural land as a soil conditioner, placed in landfills, or cleanly burned. At some plants, sludge serves as a fuel to produce energy.

1.3 Waste Water Treatment ProcessesThere are numerous processes (like Activated sludge systems, Advanced Oxidation Process, Aerated lagoon, Aerobic granular reactor, Aerobic treatment system, Anaerobic clarigester, Anaerobic digestion, API oil-water separator, Anaerobic lagoon, Bead Filter, Belt press, Bioconversion of biomass to mixed alcohol fuels, Bioreactor, Bioretention, Biorotor, Bioroll, Biolytix, Carbon filtering, Cesspit, Chlorine disinfection, Combined sewer, Composting toilet, Constructed wetland, Dissolved air flotation, Distillation, Electrocoagulation, Electrodeionization, Electrolysis, Electro-Fenton process, Expanded granular sludge bed digestion, Facultative lagoon, Fenton's reagent, Flocculation & sedimentation, Fluidized Bed Biofilter, Flotation process, Froth flotation, Fuzzy Filter, Humanure (composting), Imhoff tank , Iodine, Ion exchange, Living machines, Membrane bioreactor, Nanotechnology, N-Viro, Ozone and Ultrasound, Parallel plate oil-water separator, Recirculating Sand Filter, Reed bed, Retention basin, Reverse osmosis, Rotating biological contactor, Sand filter, Septic tank, Sequencing batch reactor, Sewage treatment, Stabilization pond, Submerged aerated filter, Treatment pond, Trickling filter, Ultrafiltration (industrial), Ultraviolet disinfection, Upflow anaerobic sludge blanket digestion, Wet oxidation etc) that can be used to clean up waste waters depending on the type and extent of contamination. Most wastewater is treated in industrial-scale wastewater treatment plants (WWTPs) which may include physical, chemical and biological treatment processes. The most important aerobic treatment system is the activated sludge process, based on the maintenance and recirculation of a complex biomass composed by micro-organisms able to absorb and adsorb the organic matter carried in the wastewater. Anaerobic processes are widely applied in the treatment of industrial wastewaters and biological sludge. Some wastewater may be highly treated and reused as reclaimed water. For some waste waters ecological approaches using reed bed systems such as constructed wetlands may be appropriate. Modern systems include tertiary treatment by micro filtration or synthetic membranes. After membrane filtration, the treated wastewater is indistinguishable from waters of natural origin of drinking quality. Nitrates can be removed from wastewater by microbial denitrification, for which a small amount of methanol is typically added to provide the bacteria with a source of carbon. Ozone Waste Water Treatment is also growing in popularity, and requires the use of an ozone generator, which decontaminates the water as Ozone bubbles percolate through the tank. Disposal of wastewaters from an industrial plant is a difficult and costly problem. Most petroleum refineries, chemical and petrochemical plants have onsite facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the local and/or national regulations regarding disposal of wastewaters into community treatment plants or into rivers, lakes or oceans.

2. Historical Aspects and Development Trend of Wastewater Treatment

In the Mesopotamian Empire (3500 to 2500 BC) some homes were connected to a storm water drain system to carry away wastes. In Babylon there were latrines which were connected to 18 inch diameter vertical shafts lined with perforated clay pipes leading to cesspools. In the Indus city of Mohenjo-Daro (Pakistan) the wealthy as well as some

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of the peasants used latrines and cesspools. These were connected to drainage systems in the streets from whence the liquid flowed to cesspools or through drains to the nearest river. Archaeologists have found four separate drainage systems at King Minos’ Royal Palace at Knossos (Crete), which dates from 1700 BC. The wastewater drained through terracotta pipes which were joined with cement into stone sewers to the Kairatos River. From 2000 BC the island of Crete had a drainage system made up of terracotta pipes. Wolfe (1999) states that many of the drains are still in use today. There was a recent discovery of a stone lavatory with running water in a royal tomb from the Western Han dynasty (206 BC to AD 24) in the central province of Henan, China (Rennie 2000). The Ancient Greeks (300 BC to 500 AD) tackled the problem of waste in a different way. They had public latrines which drained into sewers which conveyed the sewage and storm water to a collection basin outside the city to agricultural fields for irrigation.

3. Waste Water Treatment in Nepal

In Nepal, surface water pollution is one of the serious environmental problems in urban centers due to the discharge of untreated wastewater into the river-system, turning them into open sewers. Pollution of rivers is more severe and critical near urban stretches due to huge amounts of pollution load discharged by urban activities. For example, Bagmati river in Kathmandu Valley. The river suffers from severe pollution these days. The observed dry season average of biochemical oxygen demand (BOD) in the river is in the range of 20–30 mg/liter and total coli form are as high as 104–105 MPN/100 ml. Per capita pollution load discharge of urban areas has been estimated to be about 31gBOD/capita/day in Bagmati River. Regression analysis reveals pollution loads steadily increasing nearly in step with the trend in urbanization. The dissolved oxygen (DO) level of the Bagmati is declining at an average annual rate of nearly 0.3 mg/liter/year (Karna, 2001). Unplanned urbanization and industrialization occurring in the cities of Nepal may be largely responsible for this grave situation. Inadequate sewerage, on-site sanitation, and wastewater treatment facilities in one hand, and lack of effective pollution control measures and their strict enforcement on the other are the major causes of rampant discharge of pollutants in the aquatic systems.

Wastewater treatment plants are almost non-existent in the country except for a few small sized in the Kathmandu Valley and other cities and even these are not functioning well. Successful implementation of a few constructed wetland systems within the past recent years has attracted attention to this promising technology. A two-staged subsurface flow constructed wetland for hospital wastewater treatment and constructed wetlands for treatment of grey water and seepage is now becoming a demonstration site of constructed wetland systems in Nepal. To treat the wastewater of a hospital at Dhulikhel ( 40 km far from Kathmandu), a two-stage constructed wetland was built with a settlement tank, a horizontal flow bed as first stage and a vertical flow bed as second stage. The plant is operated without electric power. The aim was the elimination of organic compounds, nitrification and a significant reduction of indicator bacteria. Different phases of operation (high and low water level within the soil profile, serial operation, one stage operation) were investigated, of which the serial operation with high water level in the horizontal flow bed and low water level in the vertical flow bed showed the best elimination performance. The aril removal rate constants (k-values) turned out to be very high (especially of the vertical flow bed) compared with literature values of other subsurface flow constructed wetlands. For the vertical flow bed kCOD was 0.22 m/d and kNH sub (4)-N was 0.85 m/d during serial operation. For kNH sub (4)-N a strong correlation with the hydraulic loading rate and the COD inlet concentration was found (Laber, 1998). Beside these systems, few constructed wetlands have already been designed and some are under construction for the treatment of leach ate and seepage. The majority of urban areas do not have access to sewerage networks except three cities of Kathmandu Valley. The domestic wastewater generated from these cities is discharged into the local rivers without any treatment. Out of the total urban population only 76 % have access to toilets while the remaining use opens spaces, riverbanks for defecation. The present sewerage network in Kathmandu and Lalitpur consists of about 200 km of sewer lines. Most of sewage except Patan area is supposed to flow by gravity to the sump well at Sundarighat, from where it is to be pumped to the wastewater treatment plant at Dhobighat. This pump is provided with 2 anaerobic ponds and 1 facultative pond; having design capacity 15.4 MLD. The plant is not in operation due to non-functioning of pumping station and breakage of pumping main laid across the bed of Bagmati River. Wastewater facilities development and management is poor. The treatment plant at Balkumari 1.1 MLD capacity is partial in operation. It receives sewage by gravity from eastern part of Patan. The plant is provided with two anaerobic ponds, one facultative and one maturation pond. The sewage treatment at Bhaktapur, 2 MLD capacities is not in operation due to failure in pumping station and farmers tapped the wastewater to irrigate their cropland. The Department of Water Supply and Sewerage (DWSS) has started to construct a sewage system of about 6 km. of sewer line and a treatment plant

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(lagoon type) on 20.54 hectors to serve design population of 53000 in Thimi, Bhaktapur. The newly constructed WWTP 17.3 MLD at Guheshwori by BASP is the only plant operational in the Valley.

4. Conclusion

Treatment of wastewater is a relatively modern practice. While sewers to remove foul-smelling water were common in ancient Rome, it was not until the 19th century that large cities began to understand that they had to reduce the amount of pollutants in the used water they were discharging to the environment. Despite large supplies of fresh water and the natural ability of water to cleanse itself over time, populations had become so concentrated by 1850 that outbreaks of life-threatening diseases were traced to bacteria in the polluted water. Since that time, the practice of wastewater collection and treatment has been developed and perfected, using some of the most technically sound biological, physical, chemical, and mechanical techniques available. As a result, public health and water quality are protected better today than ever before. The modern sewer system is an engineering marvel. Homes, businesses, industries, and institutions throughout the modern world are connected to a network of below-ground pipes which transport wastewater to treatment plants before it is released to the environment.

Table: Waste water treatment Plants in Nepal

In Nepal, there are no many waste water treatment plants. The existing treatment plants and sewerage systems face a number of problems. In most cases, waste, sewer and sewage treatment systems are lacking not functioning, or operating at far below the capacity. In addition, many towns of the country are unable to operate schemes in a financially viable manner. The increasing trend of construction of sewers by municipal authorities without considering treatment facilities is posing serious threats to the environment. All industrial wastewater in most cases are directly discharged into local water bodies without any treatment. So far rivers and streams in the Kathmandu valley receive raw domestic sewage and untreated industrial waste.

References

1. http://en.wikipedia.org/wiki/Wastewater 2. http://www.adbio.com/wastewater/ww_history.htm 3. http://www.cityoflewisville.com/wcmsite/publishing.nsf/AttachmentsByTitle/

Wastewater+Treatment+History/$FILE/The+History+of+Wastewater+Treatment3.pdf4. http://www.personal.leeds.ac.uk/~cen6ddm/History/HistSewTreat.pdf 5. http://goliath.ecnext.com/coms2/summary_0199-6601581_ITM 6. http://cat.inist.fr/?aModele=afficheN&cpsidt=14052210 7. http://www.springerlink.com/content/wnpvc05hmlgykc0g/

http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=46

Plant Capacity MLD

Status Remarks

Dhobighat 15.4 Not Operational

Needs Rehabilitation

Kodku 1.1 Partial Operational

Needs Rehabilitation

Sallaghari 2.0 Partial Operational

Needs Rehabilitation

Hanumanghat

0.5 Under Construction

Needs Rehabilitation

Guheshwori 17.3 In operation

KMC FacilitiesTeku Operating Treats

SeptagePropakar Operating Just placed

in operation

38

FLIGHT CONTROL SURFACE

Mahesh Kr MaritaEngineer (A & C)

Nepal Airlines Corporation

E-VISION 2009

1. Primary Flight Controls Surface: It enables the control of an aircraft on its yaw, roll and pitch axes. This control is made possible with following control surfaces for a typical commercial aircraft:

Aileron, Roll Spoiler (Roll Control) Elevator, Horizontal Stabilizer (Pitch Control and Pitch Trim Control)

Rudder (Yaw Control)

Helicopters use the Main Rotor and the Tail Rotor Control to perform their maneuverings

Ailerons:

The two ailerons, one at the outer trailing edge of each wing, are movable surfaces that control movement about the longitudinal axis. The movement is roll. Lowering the aileron on one wing raises the aileron on the other. The wing with the lowered aileron goes up because of its increased lift, and the wing with the raised aileron goes down because of its decreased lift. Thus, the effect of moving either aileron is aided by the simultaneous and opposite movement of the aileron on the other wing. Rods or cables connect the ailerons to each other and to the control wheel (or stick) in the cockpit. When pressure is applied to the right on the control wheel, the left aileron goes down and the right aileron goes up, rolling the airplane to the right. This happens because the down movement of the left aileron increases the wing camber (curvature) and thus increases the angle of attack. The right aileron moves upward and decreases the camber, resulting in a decreased angle of attack. Thus, decreased lift on the right wing and increased lift on the left wing causes a roll and bank to the right.

Elevators:The elevators control the movement of the airplane about its lateral axis. This motion is pitch. The elevators form the rear part of the horizontal tail assembly and are free to swing up and down. They are hinged to a fixed surface--the horizontal stabilizer. Together, the horizontal stabilizer and the elevators form a single airfoil. A change in position of the elevators modifies the camber of the airfoil, which increases or decreases lift.

Like the ailerons, the elevators are connected to the control wheel (or stick) by control cables. When forward

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JUST-IN-TIME (JIT) PRODUCTION

Er. Dhruba Panthi059BME

E-VISION 2009

pressure is applied on the wheel, the elevators move downward. This increases the lift produced by the horizontal tail surfaces. The increased lift forces the tail upward, causing the nose to drop. Conversely, when back pressure is applied on the wheel, the elevators move upward, decreasing the lift produced by the horizontal tail surfaces, or maybe even producing a downward force. The tail is forced downward and the nose up.

The elevators control the angle of attack of the wings. When back pressure is applied on the control wheel, the tail lowers and the nose rises, increasing the angle of attack. Conversely, when forward pressure is applied, the tail rises and the nose lowers, decreasing the angle of attack

Rudder:

The rudder controls movement of the airplane about its vertical axis. This motion is yaw. Like the other primary control surfaces, the rudder is a movable surface hinged to a fixed surface which, in this case, is the vertical stabilizer, or fin. Its action is very much like that of the elevators, except that it swings in a different plane – from side to side instead of up and down. Control cables connect the rudder to the rudder pedals.

Trim Tabs:

A trim tab is a small, adjustable hinged surface on the trailing edge of the aileron, rudder, or elevator control surfaces. Trim tabs are labor saving devices that enable the pilot to release manual pressure on the primary controls.

Some airplanes have trim tabs on all three control surfaces that are adjustable from the cockpit; others have them only on the elevator and rudder; and some have them only on the elevator. Some trim tabs are the ground-adjustable type only.

The tab is moved in the direction opposite that of the primary control surface, to relieve pressure on the control wheel or rudder control. For example, consider the situation in which we wish to adjust the elevator trim for level flight. Level flight is the attitude of the airplane that will maintain a constant altitude. Assume that back pressure is required on the control wheel to maintain level flight and that we wish to adjust the elevator trim tab to relieve this pressure. Since we are holding back pressure, the elevator will be in the up position. The trim tab must then be adjusted downward so that the airflow striking the tab will hold the elevators in the desired position. Conversely, if forward pressure is being held, the elevators will be in the down position, so the tab must be moved upward to relieve this pressure. In this example, we are talking about the tab itself and not the cockpit control.

Rudder and aileron trim tabs operate on the same principle as the elevator trim tab to relieve pressure on the rudder pedals and sideward pressure on the control wheel, respectively.

2. Secondary Flight Control Surface:

These surfaces are required for Takeoff and Landing. They comprise High Lift Systems (Flap, Slat and Krueger Flaps) as well as Airbrakes and Ground Spoilers.

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Introduction

Just-in-time (JIT) is a management philosophy that strives to eliminate sources of manufacturing waste by producing the right part in the right place at the right time.  Waste results from any activity that adds cost without adding value, such as moving and storing.  JIT (also known as lean production or stockless production) should improve profits and return on investment by reducing inventory levels (increasing the inventory turnover rate), reducing variability, improving product quality, reducing production and delivery lead times, and reducing other costs (such as those associated with machine setup and equipment breakdown).  In a JIT system, underutilized (excess) capacity is used instead of buffer inventories to hedge against problems that may arise.

JIT applies primarily to repetitive manufacturing processes in which the same products and components are produced over and over again.  The general idea is to establish flow processes (even when the facility uses a jobbing or batch process layout) by linking work centers so that there is an even, balanced flow of materials throughout the entire production process, similar to that found in an assembly line.  To accomplish this, an attempt is made to reach the goals of driving all queues toward zero and achieving the ideal lot size of one unit.

The basic elements of JIT were developed by Toyota in the 1950's, and became known as the Toyota Production System (TPS).   JIT was firmly in place in numerous Japanese plants by the early 1970's.  JIT began to be adopted in the U.S. in the 1980's.

Some Key Elements of JIT

1) Stabilize and level the MPS with uniform plant loading (heijunka in Japanese): create a uniform load on all work centers through constant daily production (establish freeze windows to prevent changes in the production plan for some period of time) and mixed model assembly (produce roughly the same mix of products each day, using a repeating sequence if several products are produced on the same line).  Meet demand fluctuations through end item inventory rather than through fluctuations in production level.  Use of a stable production schedule also permits the use of back flushing to manage inventory: an end item’s bill of materials is periodically exploded to calculate the usage quantities of the various components that were used to make the item, eliminating the need to collect detailed usage information on the shop floor.

2) Reduce or eliminate setup times: aim for single digit setup times (less than 10 minutes) or "one touch" setup.  This can be done through better planning, process redesign, and product redesign

3) Reduce lot sizes (manufacturing and purchase): reducing setup times allows economical production of smaller lots; close cooperation with suppliers is necessary to achieve reductions in order lot sizes for purchased items, since this will require more frequent deliveries.

4) Reduce lead times (production and delivery): production lead times can be reduced by moving work stations closer together, applying group technology and cellular manufacturing concepts, reducing queue length (reducing the number of jobs waiting to be processed at a given machine), and improving the coordination and cooperation between successive processes; delivery lead times can be reduced through close cooperation with suppliers, possibly by inducing suppliers to locate closer to the factory, as Toyota has done in Japan and Honda has done in Ohio.

5) Preventive maintenance: use machine and worker idle time to maintain equipment and prevent breakdowns.

6) Flexible work force: workers should be trained to operate several machines, to perform maintenance tasks, and to perform quality inspections.  In general, JIT requires teams of competent, empowered employees who have more responsibility for their own work.  The Toyota Production System concept of “respect for people” contributes to a good relationship between workers and management.

7) Require supplier quality assurance and implement a zero defects quality program: errors leading to defective items must be eliminated, since there are no buffers of excess parts.  A quality at the source (jidoka) program must be implemented to give workers the personal responsibility for the quality of the work they do, and the authority to stop production when something goes wrong.  Techniques such as "JIT lights" (to indicate line slowdowns or stoppages) and "tally boards" (to record and analyze causes of production stoppages and slowdowns to facilitate correcting them later) may be used.

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8) Small lot (single unit) conveyance: use a control system such as a kanban (card) system (or other signaling system) to convey parts between work stations in small quantities (ideally, one unit at a time).  In its largest sense, JIT is not the same thing as a kanban system, and a kanban system is not required to implement JIT (some companies have instituted a JIT program along with a MRP system), although JIT is required to implement a kanban system and the two concepts are frequently equated with one another.

Kanban Production Control System

A kanban is a card that is attached to a storage and transport container.   It identifies the part number and container capacity, along with other information.  There are two main types of kanban (some other variations are also used):

1) Production Kanban (P-kanban): signals the need to produce more parts 2) Conveyance Kanban (C-kanban): signals the need to deliver more parts to

 the next work center (also called a "move kanban" or a "withdrawal kanban")

A kanban system is a pull system, in which the kanban is used to pull parts to the next production stage when they are needed; a MRP system (or any schedule based system) is a push system, in which a detailed production schedule for each part is used to push parts to the next production stage when scheduled.  The weakness of a push system (MRP) is that customer demand must be forecast and production lead times must be estimated.  Bad guesses (forecasts or estimates) result in excess inventory and the longer the lead time, the more room for error.  The weakness of a pull system (kanban) is that following the JIT production philosophy is essential, especially concerning the elements of short setup times and small lot sizes.

Dual-card Kanban Rules:

1) No parts made unless P-kanban authorizes production 2) Exactly one P-kanban and one C-kanban for each container (the number of containers per part number is a management

decision)

3) Only standard containers are used, and they are always filled with the prescribed (ideally, small) quantity   The number of kanban card sets required in a particular location can be calculated as: K = (expected demand during lead time + safety stock)/ (size of the container)

If rounding is necessary, K must be rounded up to the next highest integer.     Productivity Improvement with Kanban:

1) Deliberately remove buffer inventory (and/or workers) by removing kanban from the system 2) Observe and record problems (accidents, machine breakdowns, defective products or materials, production process out

of control)

3) Take corrective action to eliminate the cause of the problem

    References:

1. "Just-In-Time Production Systems: Replacing Complexity With Simplicity in Manufacturing Management" article by Richard J. Schonberger

2. Industrial Engineering , October 1984, pages 52-63;

3. Applications of Single-Card and Dual-Card Kanban, Interfaces, August 1983, pages 56-67.

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43

MODAL VIBRATION MECHANISM IN GEAR HOUSING WALLS

Er. Sanjeev Maharjan (059BME)Master’s student

College of Electrical and Mechanical EngineeringHarbin Engineering University, China

E-VISION 2009

Background:

Vibration and noise are the serious problems in structural elements and automation. Reduction of these two to desire level is the matter of concern for the researchers. Modal analysis (by applying FEM or other analytical method) provides mode shapes and natural frequency of structural elements. The mechanism related to the transmission of disturbance energy in structural elements should be considered for the safety in design to reduce vibration and noise.

1. Introduction

The use of gear transmission in both defense and commercial application has substantially increased. With the demand of high power and performance the vibration and noise on gear housing are on increasing trend. Housing wall supports gear, shaft and bearing. The power applied to the input shaft drives pinion gear. Gear rotates to mesh with another gear. At the time of meshing, the impact force generates between the gear pairs. The impact dynamic force develops the energy. Part of the energy transmits to the shaft and from shaft to bearing. Then this energy in the form of vibration is transmitted to housing wall through bearing. Figure 1 displays the gearbox model built on Pro/E software. Thus, in a power transmission system, the vibration energy generated at the gear mesh is transmitted to the gear housing and this makes structure noise producing.

Noise in gearbox is generated at gear mesh and rolling of bearings. Primary sound wave generates at the contact of

gear mesh and emits into the internal housing. The wave penetrates through the walls and transmits to the surroundings. Part of the wave energy is damped in the walls. The disturbance energy during gear contact is absorbed by structural parts such as gear, shaft, bearing and walls. The disturbance energy may excite the natural vibration of the housing wall which can create the tertial sound wave. Therefore, the housing wall acts as dual, insulator for the primary waves and the amplifier for the tertiary sound wave [1].

Figure 1 b) Gearbox without housing

44

Figure 1 a) Gearbox with housing:

ra Figure 3 a) Discrete model of the gearbox housing

E-VISION 2009

2. Vibration energy, sound power and sound radiation efficiency

The equation of motion for gear housing can be studied with the finite elements with N degree of freedom given in matrix form as,

----------- (1)

Where [M] = the mass matrix

[C] = the damping matrix

[K] = the stiffness matrix

{u (t)} = displacement vector

{f (t)} = the excitation force vector

By assuming proportional damping, the damping matrix is represented by

[c] = α [M] +β [K]

The coefficient α= 1.0[1/s] and β= 5.0×10-7[s], referring to experimental work [2]

Based on orthogonality of Eigen vectors, the vibration energy T is represented by the following expression.

------------- (2)

Here is the conjugate complex of velocity amplitude,

and and are the real and imaginary parts of

respectively.

The sound power W radiated from the structure is calculated in the frequency domain by integrating the sound intensity over the surface of the structure:

---------- (3)

Where is the surface of the structure. The sound power does not depend on the measuring point and is used as the index corresponding to the vibration energy.

The sound radiation efficiency is defined as the ratio of the radiated sound power to the power of the plane wave radiated from the plate of rigid piston motion, which has the same area as the surface of the vibrating structure. The efficiency σ is, therefore, represented by

---------- (4)

Where is the mean squared velocity of the vibrating surface with area S, and c is the sound velocity [3].

3. Modal Analysis

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Modal analysis can be obtained using software such as ANSYS, NASTRAN and others. The modal analysis of the gear housing shown in figure 3 a) is achieved by 3D brick finite element with 12 degree of freedom. The finite elements mesh contains a total of 6385 finite elements, 12950 nodes with 38850 degrees of freedom [4]

The mode shapes of oscillation become complex as the frequency increases. The three characteristics from the modal analysis can be drawn. First, the structure is divided into a certain number of zones which oscillates separately from one another with the same frequency. Waves propagate from every zone and get into collision at points which represent partitions between these zones. By analogy with the laws of physics, this oscillation represents a stationary wave and the partitions represent nodes of the stationary (standing) wave. The second characteristic is that the number of modal zones increases with increase of natural frequency. Their number doesn’t only depend on frequency but on the complexity of shapes, arrangement of ribs and other reinforcement, the thickness of walls, total dimensions of housing, shape and size of opening etc. The third characteristics is that sources of waves of natural oscillations are at points of the greatest displacement, and that at points of nodal partitions (nodes) are close to zero.

Figure 3 b) Distribution of deformations in modal shape of oscillation with frequency f= 359 Hz.

It is opposite to stresses. Stresses are greatest at points of nodal partitions which act as clamping (constraining), and they are smallest at points of wave sources where displacements are greatest.

Figure 3 c) Distribution of deformations in modal shape of oscillation with frequency f = 2540 Hz.

In figure 3 b), we can observe each of the wall forms one nodal zone. As figure 3 c), the division into

modal zones is very complex. The number of these zones is great and they are mostly distributed among the ribs and other zones of increased rigidity.

4. Software design in vibration

With the advancement in computer design, parametric modeling and auto mesh is trying to achieve for the gear housing to reduce vibration through sensitivity analysis. However, it is not easy to get parametric modeling as it consumes lots of time. The next problem is even if the parametric design is achieved, consistency of mesh can not be guaranteed. Honeywell Engines and systems has overcome this difficulty introducing CAD-independent parametric modeling technique called the contour Natural shape function [5].

5. Conclusion

By modal analysis the possible modes of housing can be obtained. In reality, conditions for these shapes excitation can not be fulfilled. Only a few out of extremely large number of modes are usually active. In real conditions, the excited modal shapes are the result of combination of way of excitation, excitation frequency, damping, transmission of exciting energy, etc. These combinations are random and modal responses are also random.

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References

[1] Ciric Kostic, S., Ognjanovic M.: The Noise Structure of Gear Transmission Units and the Role of Gearbox Walls, FME Transactions, Vol. 35, No.2, 2007.

[2] Ishikawa, M., 1989, “Study of Vibration Transmission in Gearbox,” Master Thesis (Tohoku University).

[3] Inoue Katsumi, Yamanaka M, Kihara M, “Optimum Stiffener Layout for the Reduction of Vibration and Noise of Gearbox Housing, ASME Transactions, 518, vol.124, September 2008.

[4] Ciric Kostic, S., Ognjanovic M.: Excitation of the Modal Vibrations in Gear Housing Walls, FME Transactions, Vol. 34, No.1, pp, 21-28, and 2007.

[5] S-Y Chen, Oct 200, “Integrating ANSYS with Modern Numerical Optimization Technologies”, ANSYS Solution Magazine, spring issue of 2003

47

GREASE TRAP

Er. Naveen Kumar Mallik (059BME)Site Engineer

Plumbing Contraction Company (Fajar AL Khaleej), Doha, Qatar

E-VISION 2009

Introduction

When fats, oils or grease (FOG) enters the sewer lines, it cools, solidifies and sticks to the insides of the pipes, trapping food particles and other debris. Over time, this mass continues to grow until it obstructs the flow of wastewater and causes sewage to back flow. The easiest way to solve this problem is to prevent FOG from entering the sewer system. Grease traps can be effective in controlling FOG. Proper installation, use, and proper maintenance of a grease trap will ensure separation and retention of FOG from wastewater before it enters the sewer system.

A grease trap is designed to physically separate fats, oil, and grease (FOG) and solids from kitchen wastewater and prevent it to mix with sewer waste. As wastewater enters the trap it slows down and the grease particles, which are lighter than water, coalesce and float towards the top of the tank. The heavier solid particles settle at the bottom. The trap outlet is located near the middle of the tank to prevent the grease and solids from passing through the tank. The longer the wastewater stays in the trap, the better the separation. As the layers of grease and solids increases (thickens), the retention time in the tank is reduced, separation is less complete and grease & solids are allowed to pass through to downstream plumbing.

Since oil, fats, and grease density are lower than water they float. The baffles help to retain grease toward the upstream end of the grease trap since grease floats and will generally not go under the baffle. This helps to prevent grease from leaving the grease trap and moving further downstream where it can cause blockage problems.

How grease trap works

Flow from kitchen fixtures enters the grease trap. An approved flow control or restricting device must be installed to restrict the flow to the grease trap to the

rated capacity of the trap. An air intake valve allows air into the open space of the grease trap to prevent siphoning and back-pressure. The baffles help to retain grease toward the upstream end of the grease trap since grease floats and will

generally not go under the baffle. This helps to prevent grease from leaving the grease trap and moving further downstream where it can cause blockage problems.

Solids in the wastewater that do not float will be deposited on the bottom of the grease trap and will need to be removed during routine grease trap cleaning.

Oil and grease floats on the water surface and accumulates behind the baffles. The oil and grease will be removed during routine grease trap cleaning.

Air relief is provided to maintain proper air circulation within the grease trap.

Some grease traps have a sample point at the outlet end of the trap to sample the quality of the grease trap effluent.

A cleanout is provided at the outlet or just downstream of the outlet to provide access into the pipe to remove any blockages.

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E-VISION 2009

The water exits the grease trap through the outlet pipe and continues on to the grease interceptor or to the sanitary sewer system.

Following establishments must have functioning grease trap-

Restaurants, cafeterias, hotels, hospitals, factories, clubs, and other commercial and/or institutional kitchens,

Food and meat packing and processing establishments, Supermarkets, bakeries, and other establishments where grease can be introduced into the sewer system in

large amounts.

The kitchen appliances drain to grease trap are-

All kitchen fixtures located in food prep or clean up areas should be plumbed to the grease trap. Pot sink, Prep sink, dishwasher, floor drains, trench drains, floor sinks, disposers, wok stoves, tilt kettles etc.

Grease trap cleaning procedures

No use of enzymes, acids, caustics, solvents or emulsifying products should be done when cleaning or maintaining the grease traps.

Remove lid. If the trap is equipped with removable baffles, remove them. Make sure the flow restrictor on the inflow pipe is present. Scoop the accumulated top grease layer out of the trap and deposit in a tight-sealing container for proper

disposal. Bail out water in the trap to facilitate cleaning solids from the bottom. Set water aside so you can return it

to the trap after cleaning. Note: grease haulers can remove the entire content of the trap using their vacuum system.

Remove all the solids from the bottom of the trap, drain liquids from solids and properly dispose them in the trash.

Scrape the sides, the lid, and the baffles with a putty knife to remove the grease, and deposit the grease into the same container used for the grease layer.

Replace lid and baffles.

References:

www.environmentalbiotech.com www.bwsc.org/engineering yahoo search

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27%31%

38% 41% 45% 53%

0%10%20%30%40%50%60%

2000

/01

2001

/02

2002

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2004

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2005

/06

PRODUCTION OF BIO-DIESEL FROM WASTE OIL

Er. Alok Dhungana 064MSRR501 Er. Anirudh Prasad Sah 064MSRR502 Er. Mukesh Ghimire 064MSRR511

E-VISION 2009

Background

Nepal is a net importer of petroleum product. From the graph shown below, we are spending more than 50% of our national commodity export for petroleum product.

Figure 1 Petroleum Products Import against Commodity Export of Nepal Source: Economic Survey, Govt. of Nepal, 2006/07

It is more than obvious to see that this growth is soaring in an unsustainable manner such as to overwhelm our economy in short future. This is further supported by a report on oil vulnerability of the Asian and the Pacific countries (UN, 2007), which has listed Nepal in High vulnerable countries (High OPVI). Hence we need to develop plans and policies to gradually reduce our dependency over the imported petroleum product.

Some of the promising resources are the appropriate renewable energy technologies like hydropower, bio-energy, solar energy etc.

Introduction

Bio-diesel is derived from vegetable matter which can replace diesel in vehicles. It is gaining its height recently in Nepal. There are lots of programs on plantation of Jatropa curcas over barren and marginal lands in many regions of Nepal. These programs are going to create employment and help in poverty alleviation to some extent. If these programs are not managed properly, it is going to culminate into a huge problem of use of arable land to the production of energy rather than food.

Besides, all this long process, we seem to have disregarded other sources of biodiesel like waste oil, which may be used frying oil, animal fats, waste lubricating oil etc.

In fact, bio-diesel is monoalkyl-esters of fatty acids from vegetable oils and animal fats. Biodiesel is usually brewed from the neat vegetable oil by transesterification with an alcohol, usually methanol, in presence of a catalyst, usually a base such a KOH (Fig. 2). Glycerol is a by-product of the reaction.

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Figure 2 Transesterification Reaction

Number of experiments conducted worldwide has shown exciting results. Some of the benefits of biodiesel over the petro diesel are:

•Biodiesel is a renewable energy technology.

•It saves carbon, which can be traded under CDM.

•It can be produced within the country.

•It has exceptional lubricating property; hence the life of the engine will increase dramatically.

•Production, processing & transportation induce more economic activities.

•Management of waste.

Experimental Biodiesel Production Process from Waste Oil

First the methanol and the catalyst (sodium hydroxide) are mixed. After the methanol and catalyst are mixed, they go into a reactor, where the oil is added to the mix. Used oil is first run through a filter to remove the fatty acids. This mixture is agitated continuously for 1 to 8 hours. It may also be heated during the process which decreases the viscosity and makes agitation less energy consuming. The fat or oil used is converted to esters during this stage. Care must be taken not to let this reaction converted to sopanification. Sopanification reaction produces soap instead of methyl esters.

Excess methanol must be removed in the subsequent stage of production. The methanol is removed by a flash process or by distillation. Excess methanol can also be removed after the glycerine and esters have separated. The removed methanol can be reused, in later biodiesel production.

Glycerine and methyl esters are the two major products produced after the reaction is complete and the excess methanol is removed from the mixture. The products are separated with the aid of gravity, since they have different densities. Glycerine is the denser of the two products. Glycerine is then drawn off the bottom of the tank and can be sold either as crude glycerine, or if potassium hydroxide was used as the catalyst, the salt can be used for fertilizer.

Conclusion

Hence the process is very simple and can be tested in small scale in lab. This biodiesel can be further tested on stationary and vehicle engine.

Used frying oils can be obtained from noodles factory and hotels in large volume. Motor oil from vehicle repair centre and animal fats are other major sources. They are cheap and readily available. Large scale conversion plants can produce considerable amount of biodiesel.

There are large numbers of promising energy resources all around us, yet we are always poor in energy utilization. Hence it’s the duty of us engineers to make it technically and economically viable resources.

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Fig 1: Aircraft used in World War I.

PIONEERS OF FLIGHT

Ambish Kaji Shakya

061BME 601

E-VISION 2009

Flight has fascinated mankind for centuries and countless unsuccessful flying machines had been designed. The first successful flight was made by the French Montgolfier brothers in 1783, when they flew a balloon over Paris. The next major advance was development of gliders, notably by the Englishman Sir George Cayley, who in 1845 designed the first gliders to make a sustained flight and by the German Otto Lilienthal, who become known as the first pilot because he managed to achieve controlled flights. However, powered flight did not become a practical possibility until the invention of lightweight, petrol-driven internal combustion engines in the 19th century. Then, in 1903, the American brothers Orville and Wilbur Wright made the first powered flight in their Wright Flyer Biplane which used a four-cylinder petrol- driven engine. Aircraft design advanced rapidly and in 1909 the Frenchmen Louis Bleriot made his pioneering flight across the English Channel. The American Glenn Curtiss also achieved several “firsts” in his Model- D Pusher and its variants, most notably winning the world’s first competition for airspeed at Reims in 1909.

Biplanes and Triplanes

Biplanes dominated aircraft design until the 1930s, largely because some early monoplanes were too fragile to withstand the stresses of flight. The struts between biplanes’ wings were stronger compared to those of early monoplanes, although the greater surface area of biplanes’ wings increased drag and reduced speed. Many aircraft designers also developed triplanes, which had a particular advantage over biplanes: more wings meant a shorter wingspan gave greater maneuverability. Triplanes were most successful as fighters during World War I, the Germen Fokker triplane being a notable example.

However, the greater maneuverability of triplanes was no advance for normal flying and so most manufacturers continued to make biplanes. Many other aircraft designs were attempted. Some were quadruplanes, with four pairs of wings. Some had tandem wings (two pairs of monoplane wings, one behind the other). One of the most bizarre

52

Fig 2: Aircrafts used in World War II, Hawker Tempest

E-VISION 2009

designs was by the Englishmen Horatio Phillips: it had 20 sets of narrow wings and looked rather like a Venetian blind.

World War I aircraft

When World War I started in 1914, the main purpose of military aircraft was investigation. The British-built BE 2, of which the BE2B was a variant, was well-suited to this duty: it was very stable in flight, allowing the occupants to study the terrain, take photographs, and make notes. The BE 2 was also one of the first aircraft to drop bombs. One of the biggest problems for aircraft designers during the war was to mount machine guns. On aircraft that had front-mounted propellers, the field of fire was restricted by the propellers and other parts of the aircraft. The problem was solved in 1915 by the Dutchman Anthony Fokker, who designed an interrupter gear that prevented a machine-gun from firing when a propeller blade passed in front of the barrel. The German LVG CVI had a forward-firing gun to the right of the engine, as well as a rear-cockpit gun, and a bombing capability. It was one of the most versatile aircraft of the war.

Early passenger aircraft

Until the 1930s, most passenger aircraft were biplanes, with two pairs of wings and a wooden or metal framework covered with fabric or sometimes plywood. Such aircraft were restricted to low speeds and low altitudes because of the drag on their wings. Many had an open cockpit, situated behind or in front of an enclosed-but unpressurized-cabin that carried a maximum of ten people. The passengers usually sat in wicker chairs that were not bolted to the floor, and the journey could be bumpy when flying through turbulence. Warm clothing, and ear plugs to reduce the effects of prolonged noise, was often required. During the 1930s, powerful, streamlined, all-metal monoplanes such as the Lockheed Electra became widespread. By 1939, the advent of pressurized cabins allowed fast flights at high altitudes, where there is less turbulence. Flying boats were still necessary on many routes until 1945 because of inadequate runways and the frequency of emergency sea-landings. World War II, however, resulted in enough good runways being built for land-planes to become standard on all major airline routes.

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World War II aircraft

WHEN WORLD WAR II began in 1939, air forces had already replaced most of their fabric-skinned biplanes with all -metal, stressed-skin monoplanes. Aircraft played a far great role in military operations during World War II than ever before. The wide range of aircraft duties and the introduction of radar tracking and guidance systems put pressure on designers to improve aircraft performance. The main areas of improvement were speed, range, and engine power. Bombers became larger and more powerful-converting from two to four engines-in orders to carry a heavier bomb load; the US B-17 Flying fortress could carry up to 6.1tons of bombs over a distance of about 3,200 km (2,000 miles). Some aircraft increased their range by using drop tanks (fuel tanks that were jettisoned when empty to reduce drag). Fighters needed speed and maneuverability: the Hawker Tempest had a maximum speed of 700 kmph (435 mph), and was one of the few Allied aircraft capable of catching the German jet-powered V1 “flying Bomb”. By 1944, Britain had introduced its first turbojet-powered aircraft, the Gloster Meteor fighter, and Germany had in the world, the turbojet-powered Me 262, which had a maximum speed of 868 kmph (540 mph).

54

KNOWING CATIA

Dave Shrestha 061BME611

Fig: Using CATIA for simulation of machine tool

E-VISION 2009

Introduction

CATIA (Computer Aided Three Dimensional Interactive Application) is a multi-platform CAD/CAM/CAE commercial software suite developed by the French company Dassault Systemes and marketed worldwide by IBM. Written in the C++ programming language, CATIA is the cornerstone of the Dassault Systemes product lifecycle management software suite.

The software was created in the late 1970s and early 1980s to develop Dassault's Mirage fighter jet, and then was adopted in the aerospace, automotive, shipbuilding, and other industries.

Historical Background for CATIA

CATIA started as an in-house development by French aircraft manufacturer Avions Marcel Dassault, at that time customer of the CADAM CAD software.

Initially named CATI (Conception Assistée Tridimensionnelle Interactive — French for Interactive Aided Three Dimensional Design) — it was renamed CATIA in 1981, when Dassault created a subsidiary to develop and sell the software, and signed a non-exclusive distribution agreement with IBM.

In 1984, the Boeing Company chose CATIA as its main 3D CAD tool, becoming its largest customer.

In 1988, CATIA version 3 was ported from the mainframe computers to UNIX.

In 1990, General Dynamics Electric Boat Corp chose CATIA as its main 3D CAD tool, to design the U.S. Navy's Virginia class submarine.

In 1992, CADAM was purchased from IBM and the next year CATIA CADAM v4 was published. In

1996, it was ported from one to four Unix operating systems, including IBM AIX, Silicon Graphics IRIX,

Sun Microsystems SunOS and Hewlett-Packard HP-UX.In 1998, an entirely rewritten version of CATIA,

55

Fig: Using CATIA for seat design

E-VISION 2009

CATIA V5 was released, with support for UNIX, Windows NT and Windows XP since 2001.

In 2008, Dassault announced CATIA V6. Support for any operating system other than Windows is dropped.

Features

Commonly referred to as a 3D Product Lifecycle Management software suite, CATIA supports multiple stages of product development, from conceptualization, design (CAD), manufacturing (CAM), and analysis (CAE).

CATIA can be customized via application programming interfaces (API). V4 can be adapted in the FORTRAN and C programming languages under an API called CAA. V5 can be adapted via the Visual Basic and C++ programming languages, an API called CAA2 or CAA V5 that is a component object model (COM)-like interface.

Although later versions of CATIA V4 implemented NURBS, V4 principally used piecewise polynomial surfaces. CATIA V4 uses a non-manifold solid engine.

Catia V5 features a parametric solid/surface-based package which uses NURBS as the core surface representation and has several workbenches that provide KBE support.

As of 2008[update], the latest release is V5 release 19 (V5R19).

V5 can work with other applications, including Enovia, Smarteam, and various CAE Analysis applications.

Supported Operating Systems and Platforms

CATIA V5 runs on Microsoft Windows (both 32-bit and 64-bit), and as of Release 18 Service Pack 4 on Windows Vista 64. IBM AIX, Hewlett Packard HP-UX and Sun Microsystems Solaris are supported.

CATIA V4 is supported for those Unixes[ and IBM MVS and VM/CMS mainframe platforms up to release 1.7.

CATIA V3 and earlier run on the mainframe platforms.

CATIA- using Industries

CATIA is widely used throughout the engineering industry, especially in the automotive and aerospace sectors. CATIA V4, CATIA V5, Pro/ENGINEER, NX (formerly Unigraphics), and SolidWorks are the dominant systems.

1. Aerospace

The Boeing Company used CATIA V3 to develop its 777 airliner, and is currently using CATIA V5 for the 787 series aircraft. They have employed the full range

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E-VISION 2009

of Dassault Systemes' 3D PLM products, comprised of CATIA, DELMIA, and ENOVIA LCA, supplemented by Boeing developed applications.

European aerospace giant Airbus has been using CATIA since 2001.

Canadian aircraft maker Bombardier Aerospace has done all of its designing on CATIA.

2. Automotive

Automotive companies that use CATIA to varying degrees are BMW, Porsche, Daimler Chrysler [2] , Audi, Volkswagen, Volvo, Fiat, Gestamp Automocion, Benteler AG, PSA Peugeot Citroën, Renault, Toyota, Honda, Ford, Scania, Hyundai,Škoda Auto, Proton, Tata motors and Mahindra.

Goodyear uses it in making tires for automotive and aerospace and also uses a customized CATIA for its design and development. All automotive companies use CATIA for car structures — door beams, IP supports, bumper beams, roof rails, side rails, body components — because CATIA is very good in surface creation and Computer representation of surfaces.

3. Shipbuilding

Dassault Systems has begun serving shipbuilders with CATIA V5 release 8, which includes special features useful to shipbuilders. GD Electric Boat used CATIA to design the latest fast attack submarine class for the United States Navy, the Virginia class. Northrop Grumman Newport News also used CATIA to design the Gerald R. Ford class of supercarriers for the US Navy.

4. Other

Architect Frank Gehry has used the software, through the C-Cubed Virtual Architecture company, now Virtual Build Team, to design his award-winning curvilinear buildings. His technology arm, Gehry Technologies, has been developing software based on CATIA V5 named Digital Project. Digital Project has been used to design buildings and has successfully completed a handful of projects.

F uture Implementations

Dassault Systemes has announced plans to release CATIA Version 6 (V6) in mid-2008. The new interface allows designers to manipulate the 3D solid model directly rather than the feature based design approach employed in CATIA V5.

References

1. Wikipedia, the free encyclopedia

http://en.wikipedia.org/wiki/Main_Page

2. A short history of CATIA & Dassault Systemes

http://www.edstechnologies.com/download/history-catia.pdf

57

MOONBUGGY: AN INTRODUCTION

Jatin Man Amatya 061BME613

Ujuma Shrestha 061BME647

E-VISION 2009

The vehicle moon buggy derived its name from the off-road vehicle designed by National Aeronautics and Space Administration (NASA) to be driven in the rough terrains of the moon. NASA organizes a race called “The great moon buggy race” for the students of various colleges to participate with their own design of the buggy at Huntsville Alabama every year. NASA has certain criteria which is needed to be fulfilled by the vehicle built for participating in the race. The students have to develop a vehicle which is operated by muscular strength and should not use any energy storage devices like flywheel, batteries etc. The design of a vehicle addresses engineering problems similar to problems faced by the engineers who designed the original lunar vehicle. These include functionality, drive type, safety, assembly and disassembly requirement. It has to withstand high parameter and demands according to commission of NASA. Though moon buggy name was derived from a NASA project it actually now is the project for students to show their skill in human powered vehicle design.

The Moon Buggy Race has many requirements which affect the design of the Moon Buggy and the qualifications for the awards. Each Moon Buggy is required to carry two students, one male and one female for the duration of the course. This course consists of approximately one half of a mile of “lunar” surface composed of craters, rocks, lava, inclines and “lunar” soil. During the competition the two riders are required to carry the Moon Buggy disassembled to the starting line within a 4’ x 4’ x 4’volume, mimicking the requirements of the original lunar roving vehicle. At the starting line the Moon Buggy will be assembled, tested for safety and set up for course testing. At this point the design team will be evaluated on the time required to safely traverse the course. Each team is allowed two runs through the “lunar” terrain and the shortest time will be added to the assembly time for a total time for this competition. Awards are given to the three teams with the shortest time in assembling the vehicle and navigating the course. The completed Moon Buggy will be evaluated on functionality separate from the race. This evaluation will examine the technical approach used to solve the engineering problem of navigating the lunar course and not the time needed to traverse the course.

58

CARBON NANOTUBE IN NANOTECHNOLOGY

Kundan Lal Das

061BME614

E-VISION 2009

Nanotechnology began being promoted as a key component of future technology in the late 1970s. The term nanotechnology was first used in 1974 by Japanese scientist Norio Taniguchi in a paper titled “On the Basic Concept of Nanotechnology.” However, the term was also used by American engineer K. Eric Drexler in the book Engines of Creation (1986), which had a greater impact and helped accelerate the growth of the field. By this time, major breakthroughs had been achieved in industry, such as the formation of nanoparticle catalysts made of non reactive metals and used in catalytic converters found in automobiles. These catalysts chemically reduced noxious nitrogen oxides to benign nitrogen and simultaneously oxidized poisonous carbon monoxide to form carbon dioxide.

The Tools of Nanotechnology

The scientific community began serious work in nanoscience when tools became available in the late 1970s and early 1980s—first to probe and later to manipulate and control materials and systems at the nanoscale. These tools include the transmission electron microscope (TEM), the atomic force microscope (AFM), and the scanning tunneling microscope (STM).

Contribution of Dr. Samio Lijima

In 1971 he developed World’s first high- resolution electron microscope at Arizona state University

In 1980 he discussed about Onion shaped graphite in his PhD paper

He found that the fifth state of carbon was the carbon nanotube. He developed Multi-walled Carbon Nanotube (CNT) in 1991 He developed Single-walled CNT in 1993

Carbon nanotube

Carbon nanotube is a one dimensional quantum wire of diameter of few nanometer diameters and several nanometer of length. It is formed by rolling graphene sheet. The chemical bonding of nanotubes are entirely of sp 2 bonds , which is stronger than the sp 3 bonds found in diamond, provides the molecules with their unique strength.

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Properties of Carbon Nanotube

The properties of carbon nanotube may be classified under mechanical properties, electrical properties, thermal properties, magnetic properties, field effect, and optical properties. Some of them are listed below.

Mechanical properties:

The carbon nanotube possesses wonderful mechanical properties. The sp² carbon-carbon bond gives carbon nanotubes amazing mechanical properties. The Young's modulus of the best nanotubes can be as high as 1000 GPa which is approximately 5 times higher than steel. The tensile strength or breaking strain of nanotubes can be up to 63 GPa, around 50 times higher than steel. These properties, coupled with the lightness of carbon nanotubes, give them great potential in applications such as aerospace. It has even been suggested that nanotubes could be used in the “space elevator”, an Earth-to-space cable first proposed by Arthur C. Clarke.

Electrical

Some nanotubes have conductivities higher than that of copper, while others behave more like silicon. There is great interest in the possibility of constructing nanoscale electronic devices from nanotubes. For a given (n,m) nanotube, if n - m is a multiple of 3, then the nanotube is metallic, otherwise the nanotube is a semiconductor. For (n = m) nanotubes are metallic, and nanotubes (5,0), (6,4), (9,1), etc. are semi conducting.

Thermal properties :

All nanotubes are expected to be very good thermal conductors along the tube, exhibiting a property known as "ballistic conduction," but good insulators laterally to the tube axis. It is predicted that carbon nanotubes will be able to transmit up to 6000watts per meter per Kelvin at room temperature; compare this to copper, a metal well-known for its good thermal conductivity, which only transmits 385 W/m/K. The temperature stability of carbon nanotubes is estimated to be up to 2800 degrees Celsius in vacuum and about 750 degrees Celsius in air.

Magnetic properties:

It is magnetized when it is placed in contact with magnetic materials. It has very weak ferromagnetic property. The basic electrical property changes from semiconductor to metal in strong magnetic field. Band gap shrink in strong magnetic field.

Applications of Carbon Nanotube The carbon nanotube has numerous applications visible in the real world. Some of them being space elevator, supercapacitor, hydrogen storage, atomic force microscope, memory device, molecular electronics, thermal materials, biomedical, air water filteration etc.

a. Space elevator Carbon nanotube having strong carbon-carbon bond has wonderful mechanical property. It is also lighter than steel. These property favours the use of this material as the most ambitious space elevator.

b. Supercapacitor or Ultracapacitor

Supercapacitors are electrical storage devices that can deliver a huge amount of energy in a short time. Supercapacitors that can deliver a strong surge of

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electrical power could be manufactured from carbon nanotubes . The charge and discharge processes are very fast at the interface between the nanotube electrode and electrolyte solution. The high speeds of charge and discharge suggest a possible application of this kind of multi-walled carbon nanotubes to supercapacitor.

c. Hydrogen storage:

Since the carbon nanotubes has the high hydrogen adsorption property at less pore diameter, equipped with high mechanical strength, therefore it can be used as the material for the adsorption of the hydrogen which is the obstacle for the hydrogen fuel cell vehicle or other hydrogen energy technology.

It sounds like the development of carbon nanotubes tends to solve most of the problems and obstacles prevalent in the research world, especially those in the field of material science and engineering. But still we have to go a long way for the maturation of the research for carbon nanotubes. With its discovery we can endeavor the ladder to the space or the highway to the moon. It seems all like a dream. But still we should not stop dreaming.

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Fig. Space Elevator

MATERIAL SELECTION: SITKA SPRUCE FOR VIOLIN

Roma Gurung

061BME633

E-VISION 2009

Background:

Music is a universal language: it connects the gap of verbal language. The magic behind the music is its uniqueness; music has its own identity according to the musical instrument. The musical instruments are different to each other in respect of their structure and building material. The material selection for the musical instrument plays a vital role in the production of a specific music/tone. Accordingly now we could think why the top plates of violins and cellos, for example, are always made from sitka spruce and the backs from curly maple, and the special varnish used was one of the secrets of Stradivarius? Why clarinets are made from Africa blackwood, recorders from apple or pear wood? Why trumpets and trombones are made from brass, plated with silver? Why bells are made from bronze and organ pipes from a tin-lead alloy? In a spirit of inquiry, it makes sense to ask how well founded these traditions are.

Within this wide range of material availability for musical instrument, we will examine the most widely used material since centuries ago – the wood for the violin. After a long period of evolution in the history of mankind, the skill and devotion of luthiers have established the most appropriate wood species for typical instruments. The organization of the instruments in an orchestra is based on four main standard groups: the strings, the woodwinds, the brasses, and the percussion. And the Wood is used for strings, woodwind, and percussion instruments. Undoubtedly, among all the string instruments, the violin is the most fascinating.

In string instruments, basically, vibrating strings are too thin to radiate any appreciable amount of acoustic energy, and it is therefore essential that they be coupled to some sort of radiating structure- a vented box in a violin. The shape and material of the vented box will affect the sound and response of the instrument.

The important material parameters for the radiating structure are the speed of vibrational waves, the mechanical impedance (sound wave resistance) and the mechanical damping of the material. In wood, the Young’s modulus is very different along the grain and across the grain, the ratio being as high as 20:1 for spruce and as low as 3:1 for some other woods, which means that, even if average properties are matched by some other material, the frequencies of the vibrational modes will be quite different. Because of this anisotropy, the wood in violin and guitar tops always has its grain running along the length of the instrument, and something similar is built into pianos and harpsichords.

The internal damping of the wood has a rather different effect, since it becomes most important at high frequencies, and again differs considerably from one timber or another, and even from one tree to another of the same timber. If the high-frequency damping losses are very low, then the sound will be bright and clear, while if they are larger the sound will be smooth and mellow.

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The material selection for Violin:

The violin implies the different types of wood for its different parts: Spruce (Picea abies) used for the top plate and Curly Maple used for the backplate, ribs, and neck of the violin. These species of wood are categorized under the name of ‘resonance wood’ that consists of all species with remarkably regular anatomical structure and high acoustic properties.

In the understanding of material selection, violin makers traditionally select their boards according to the simplest anatomical criteria-straight grain, fine texture, and low density-supplemented with rather crude bending tests. Other criteria concern the constitution of the annual ring: for violins and violas, 1mm average ring width (0.8-2.5mm are the limits); proportion latewood in the annual ring, typically in the order of ¼; and the discrepancy between the respective densities of latewood and earlywood, as wide as possible, typically 900 and 280 kg/m3, respectively, so that the overall density in maintained around 400 kg/m3. The transition between earlywood and latewood must be as smooth as possible. Compression wood is completely rejected. The luthier’s general Criterion is that a regular structure is the primary requirement for soundboards. And at present, the regularity of the annual ring width can be determined using X-ray microdensitometric analysis (Bucur 1984c) or image analysis (di Bella et al. 2002). Final sophisticated selection is achieved through bending tests. The result is that matched soundboards exhibit similar elastic behavior (Ono and Kataoka).

Furthermore, for curlymaple the most important criterion of selection is the beauty of the wavy grains structure. At first glance, this criterion is obviously concerned with the aesthetic aspect of the instrument. The very complex structure of curly maple plays an important role in its acoustical behavior.

Acoustical Properties of Resonance Wood for Violins

The acoustical behavior of wood material during the vibration of violin plates is related:

1. To the elasticity of the material along or across the grain, under extensional or bending vibrations; and2. To the internal friction phenomena caused by the dissipation of vibrational energy.

In a solid body such as wood three kinds of vibratory resonant motion are possible:

a. Longitudinal resonant vibrations which can be taken as the dynamic analogue of axial stresses acting in a short column. The longitudinal resonance methods can be applied for determining the elastic constants, the sound velocity, and the logarithmic decrement.

b. Transverse resonant vibrations or flexural vibrations, corresponding to static bending in a wooden beam, are the most frequent dynamic stresses in structural parts, such as trusses, joists and spars.

c. Torsional resonant vibrations as the dynamic counterpart to the static torsion. Decisive for the internal stress and the fundamental resonant frequency is the modulus of rigidity G of the wood.

Theoretical understanding of the propagation of linear vibration in solids and technological advances between 1948 and 1990 permitted the development of the frequency resonance method, using thin strips of wood for the measurement of elastic constants, along and across the grain (Young’s moduli EL and ER and shear moduli GLR and GLT), as well as the corresponding damping constants, expressed as the logarithmic decrecment and commonly noted

in the literature as Tan and Tan or quality factor QL or QR. The frequency resonance method also allows access

to the corresponding sound velocity of extensional or bending waves. Knowing the density of the material ( ),

acoustic impedance (V× ) and acoustic radiation (V/ ) can be deduced. This last parameter can help in matching

two violin plates with different Stiffnesses and densities but on which the ratio (V/ ) is identical (Schelleng 1982).

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In addition to these advancement,an important step in the mechanical characterization of wood for violins was achieved when the ultrasonic velocity method, at 1 MHz frequency, was used for the determination of 12 elastic constants (3 Young’s moduli, 3 Shear moduli, and 6 Poisson’s ratios) (Bucur 1987b).

The wave length in the case of the propagation of longitudinal waves along the axis of the rod, the sound velocity v is,

where E= modulus of elasticity (Young’s modulus) and = density of the wood.

The propagation velocity of elastic torsional waves depends on the modulus of rigidity G. thus,

where G= modulus of rigidity (shear modulus)

Among different varieties of wood used for the violin, the acoustical behavior of most essential spruce wood will be examined further.Spruce resonance wood:

The following table 1 and 2 give the experimental data for the two important characteristics of acoustical behavior of the Picea species - spruce wood used for the top of the violin. Refering the data in table 1, we note the very high values of modulus of elasticity parallel to the longitudinal direction (EL) compared to that in the radial direction (ER). Also we note the very low values of modulus of rigidity along tangential-radial plane (GTR) compared to that in the tangential-longitudinal plane. And this gives an idea of the high anisotropy of spruce.

It is well known that if no external periodic forces are acting on a solid vibrating body it returns to the static condition. The successive amplitudes become lower and lower since the original inherent energy is dissipated partly by radiation of sound, partly by internal friction, which produces heat and which is called ‘damping capacity’ because it decays the free vibrations in the wooden member. In the case of free vibrations the decrease in amplitudes of two successive cycles of vibration follows a logarithmic law. Therefore the logarithmic decrement may be

computed as ln where A1 and A2 are the amplitudes of two succeeding cycles. The damping capacity of wood is

higher than it is for most other structural materials.

Sound velocity in wood, parallel to the fiber, has about the same magnitude as sound velocity in metals except lead. The density of wood amounts to only 1/20 to 1/10 of the density of technically used metals. Consequently the sound wave resistance w, which is decisive for the propagation of sound and especially for the reflection of sound at the

boundary between two media, is quite different for woods and metals since

The decay of the free vibrations of any plates is caused partly by damping due to internal friction and partly by damping due to sound radiation. Damping due to sound radiation depends mainly on the ratio of sound velocity to density for a particular material. Comparing woods with metals the acoustical superiority of the former becomes evident. In musical instruments, e.g. sounding boards of pianos or violins, low damping due to internal friction and high damping due to sound radiation is desirable.

Spruce has the quality of high damping of sound radiation at low sound wave resistance (Horig 1929).

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Table 2 shows the damping constants at low frequency and high frequency measured by the resonance method using strips. It can be noted that the damping constants are highly influenced by the range of frequency and by the anisotropic direction, i.e., by the anatomical structure. The damping coefficients are higher in the radial (R) direction than in the longitudinal (L) direction.

Furthermore, it is quite interesting to observe that the properties of spruce vary according to the location and environment of the tree growth (refer table 3)

It is evident from table 3 that the density and the dynamic properties of Japanese species are in the same range as those of European resonance spruce. Barlow (1997) presented a very innovative approach for the selection of materials for music instruments by introducing “merit indices”, which are ratios of the values of different mechanical properties – Young’s moduli – to density. These indices are used in conjunction with maps of the values of mechanical properties versus density and wood microstructure.

In conclusion, wood is a unique material for musical instruments and acoustic purposes. Among the various musical instrument and material used in them, the study of experimental data of the acoustical behavior (anisotropic nature and internal damping) for the spruce wood for the top of violin justified its application. Also the variation in the acoustical behavior due to the location has also been examined.

SpeciesDensity (kg/m3)

Logarithmic decrement at low frequency Logarithmic decrement at high frequency

Axis L Axis R Axis L Axis R

Frequ-ency

Frequ-ency

Frequ-ency

Frequ-ency

Spruce480 0.022 642 0.069 1046 0.084 16587 0.098 13130

440 0.021 779 0.058 753 0.075 13025 0.077 12008

Sitka

Spruce

480 0.030 425 0.063 190 0.049 14551 0.071 11311

460 0.032 552 0.059 1159 0.081 11332 0.070 12042

Red

spruce

480 0.022 873 0.074 553 0.052 9931 0.120 8074

450 0.022 797 0.063 696 0.052 9613 0.072 8718

White

Spruce

480 0.023 547 0.063 4454 - - - -

460 0.022 591 0.066 437 0.064 12817 0.082 14527

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Table 1. Dynamic elastic constants and corresponding velocities of spruce (Picea spp.) used for musical instruments. (Haines 1979)

Table 2 Damping constants (logarithmic decrement) measured with the resonance method at different frequencies. (Haines 1979)

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Species Density Velocity (m/s) Young’s Shear moduli

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Table 3 Acoustic and elastic properties of spruce (Picea spp.) logs for musical instruments of different origins (Japanese, Canadian, European). (Ono 1983b)

E-VISION 2009

(kg/m3)

moduli

(108 N/m2)(108 N/m2)

VLL VRR VTL VTR EL ER GTL GTR

Spruce 480 5600 1200 1307 359 150 7.4 8.2 0.62

440 600 1100 1215 316 160 5.0 6.5 0.44

Sitka spruce480 5200 1700 1581 309 130 13 12 0.46

460 5200 1500 1062 242 130 11 5.1 0.27

Red spruce 480 6300 950 1060 277 90 4.8 5.4 0.37

450 5700 1300 1192 305 150 7.9 6.4 0.42

White spruce

480 5200 1600 1241 306 130 12 7.4 0.45

460 5700 1600 1224 339 150 12 6.9 0.53

Species Origin Age (years) Diameter (cm)Density (kg/m3)

EL (108N/m2) QL

P. glehnii Japan 325 62 427 119 164

P . jezoensis Japan 150 52 428 129 171

P. sitchensis Canada 315 137 424 109 137

P. abies Germany 200 60 445 142 177

References:

1. Acoustics of Wood; Bucur,Voichita. ;CRC Press, New York 19952. “Material For Musical Instruments”;Neville Fletcher; Research School Of Physical Sciences And Engineering;

Australian National University 3. “Wood Properties”; Jerrold E. Winandy, USDA-Forest Service, Forest Products Laboratory, Wisconsin4. “Mechanical Properties of Wood”; David W.Green, Jerrold E. Winandy, David E. Krestschmann.

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COMPUTATIONAL FLUID DYNAMICS: AN INTRODUCTION

Anil Kunwar

061BME603

E-VISION 2009

What is Computational Fluid Dynamics (CFD)?

Fluid (liquid and gas) flows are governed by partial differential equations (PDE) which represent conservation laws for the mass, momentum and energy. Computational Fluid Dynamics is the art of replacing such PDE systems by a set of algebraic equations which can be solved using digital computers.

CFD provides a qualitative and sometimes even quantitative prediction of fluid flows by means of

Mathematical modeling (partial differential equations) Numerical methods (discretization and solution techniques) Software tools ( solvers , pre and post-processing utilities )

CFD is a combination of three disciplines: theoretical fluid dynamics, numerical mathematics and computer science. It uses a computer to solve the mathematical equations for problem of fluid dynamics at hand. Thus, it enables scientists and engineers to perform ‘numerical experiments (computer simulations)’ in a ‘virtual flow laboratory’.

Historical Background for CFD

In the 18th and 19th centuries, significant work was done trying to mathematically describe the motion of fluids. Daniel Bernoulli (1700-1782) derived Bernoulli's famous equation, and Leonhard Euler (1707-1783) proposed the Euler equations, which describe the conservation of momentum for an inviscid fluid, and conservation of mass. He also proposed the velocity potential theory. Two other very important contributors to the field of fluid flow emerged at this time; the Frenchman, Claude Louis Marie Henry Navier (1785-1836) and the Irishman, George Gabriel Stokes (1819-1903) who introduced viscous transport into the Euler equations, which resulted in the now famous Navier-Stokes equation. These forms of the differential mathematical equations that they proposed nearly 200 years ago are the basis of the modern day computational fluid dynamics (CFD) industry, and they include expressions for the conservation of mass, momentum, pressure, species and turbulence. Indeed, the equations are so closely coupled and difficult to solve that it was not until the advent of modern digital computers in the 1960s and 1970s that they could be resolved for real flow problems within reasonable timescales. Other key figures who developed theories related to fluid flow in the 19th century were Jean Le Rond d'Alembert, Siméon-Denis Poisson, Joseph Louis Lagrange, Jean Louis Marie Poiseuille, John William Rayleigh, M. Maurice Couette, Osborne Reynolds, and Pierre Simon de Laplace.

The major pioneering works in the field of modern day CFD was done by Richardson and Courant and colleagues; they combined theoretical fluid dynamics and numerical mathematics. A substantial part of Euler and Navier-Stokes Software used worldwide now, is based on a journal distilled by the mathematician Sergei Konstantinovich Godunov, from his Ph. D thesis .Similarly, Peter D. Lax has contributed several mathematical discoveries of importance to CFD. Importantly, John von Neumann and others have efforted in implementing the discipline of computer science to enable the integral enhancement of CFD .In 1940s , Von Neumann and Richtmeyer collaborated in the development of the artificial viscous method ,leading to capturing of shock waves

Daimler Chrysler was the first company to use CFD in Automotive sector. Speedo was the first swimwear company to use CFD.

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Steps for applying CFD for analyzing fluid problems

First the mathematical equations describing the fluid flow are written .These are usually a set of partial differential equations. These equations are then discretized to produce a numerical analogue to the equations .The domain is then divided into small grids or elements .Finally the initial conditions and boundary conditions of the specific problems are used to solve these equations .The solution methods can be direct or iterative. In addition, certain control parameters are used to control the convergence, accuracy and stability of the method.

Elements of CFD codes:

1. A pre- processor, which is used to input the problem geometry, generates the grid; define the flow parameter and the boundary conditions to the code.

2. A flow solver, which is used to solve the governing equations of the flow subjects to the conditions provided. There are 4 different methods used as flow solver: finite difference method (FDM), finite element method (FEM), finite volume method (FVM), and spectral method.

3. A post processor, which is used to massage the data and show the results in graphical and easy to read format.

Experiments Vs Simulations

CFD gives insight to flow patterns that are difficult, expensive and impossible to study using traditional (experimental) techniques.

Experiments Simulations (via CFD)Quantitative description of flow phenomena using measurements for one quantity at a time at a limited number of points and time instants for a laboratory-scale model for a limited range of problems and operating

conditionsError sources: measurement errors , flow disturbances by probes

Quantitative prediction of flow phenomena using CFD software

for all desired quantities with high resolution in space and time for the actual flow domain for virtually any problem and realistic operating

conditions Error sources: modeling, discretization , iteration , implementation

Applications of CFD

CFD is used in wide variety of disciplines and sectors, including aerospace, automotive, power generation, chemical manufacturing, polymer processing, petroleum exploration, pulp and paper operation, medical research, meteorology, astrophysics, effect analysis of missiles and shells etc.

As shown in the figures, CFD simulation has been used in aerodynamic shape design and analyzing the smoke plume from an oil fire. Thus, the limitations of experimental analysis method have been greatly overcome by this method.

Reliability of CFD simulations:

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The results of a CFD simulation are never 100% reliable because

the input data may involve too much guessing or imprecision the mathematical model of the problem at hand may be inadequate the accuracy of the results is limited by the available computing power

The reliability of CFD simulations is greater for laminar / slow flows than for turbulent / fast ones for single-phase flows than for multi-phase ones for chemically inert systems than for reactive flows

Available CFD Softwares:

Some of the CFD softwares that are in use are as following:-

software website remarksANSYS CFX http: // www.ansys.com commercialFLUENT http: // www.fluent.com commercialSTAR-CD http: // www.cd-adapco.com commercialFEMLAB http: // www.comsol.com commercialFEATFLOW http: // www.featflow.de open- sourceConclusion:

CFD is a highly interdisciplinary research area which lies at the interface of physics, applied mathematics and computer science. With the emergence of CFD, the solutions of complicated, difficult and impossible flow problems can be obtained via computer simulations.

CFD is attractive to industry and research based projects since it is more cost effective than physical testing. CFD simulations are cheaper, faster, easier and of multipurpose than the process carried for physical experimentation. However, one must note that complex flow simulations are challenging and error- prone and it takes a lot of engineering expertise to obtain validated solutions.

The merits and limitations of CFD are both the encouraging factors for scientists and engineers of today to perform extensive research in this field.

References:

1. Das , Tarit Kumar , Computational Fluid Dynamics , Wiley Eastern Limited ,19802. Korren, Barry ;Computational Fluid Dynamics : Science and Tool ; Centrum voor Wiskunde en

Informatica, Amsterdam , Netherlands ,2006

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Tired Guys!!! Long way to go….during Gorkha Tour

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3. Ashgriz,N.,Mostaghimi,J.; Fluid flow handbook, Toronto , Canada4. Bhaskaran Rajesh ,Collins Lance ; Introduction to CFD Basics5. http:// www.mathematik.uni-dortmund.de/kuzmin/cfd intro/cfd.html 6. http://www.fluent.com/about/cfdhistory.htm

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UNDERGROUND TUNNEL AND TUNNELING METHODS

Rajkumar Chaulagain 061BME629

E-VISION 2009

Introduction

Tunnels are artificial passage built underground to facilitate transportation, storage or protection. Tunnels have been built from time immemorial for various purposes. The earliest known tunnel was constructed about 4000 years ago by Queen Semiramis in ancient Babylon under the Euphrates River to connect her palace and the temple of Jove. The tunnel was 1 Km long and was of section 3.6 x 4.5 m.The principal function for which tunnels other than mining tunnels and military sappers tunnels , are build include :

1. Transportation

People and goods : Pedestrian and cycle subway, Railways and motors, Highways Water: Canals, City supplies, Irrigation, Hydroelectric power, Cooking water Sewers Cables and pipe services

2. Storage and plant

Car parks Cavern storage of oil Underground power stations Military stocks Disposal of radioactive waste

3. Protection of people

Shelters Control posts

The fundamental operations of tunneling are: 1. Survey2. Tunneling operations, apart from fixing the alignment and the lining (which are the preliminary and final

aspects of constructions of a tunnel) comprises these intermediate operations:Excavation : applicable to soft soilsPicking : applicable to medium soils and very sift rocks Blasting : applicable to medium and hard rocks.

3. Fixing temporary supports, as necessary.4. Removal of bladed/excavated material.5. Dressing, fixing final supports, followed by final operation of lining, wherever necessary.Where all condition are favorable, construction becomes relatively simple, but the history of tunneling shows how often unexpected physical conditions have made a project impossible as originally conceived , and ultimately only achievable, after years of immense effect, by virtue of new method.Factors related to tunneling function

The factors related to above fundamental operations are mutually interdependent and are not separate for decision making. Those are

1) Situation for a tunnel may be through a mountain or hill, or subaqueous, or urban.2) Ground may be anything from soft silt to hard uniform rock covering a very wide range of behaviors in

excavation; water may play an important part. Any choice of ground implies changes in geometry, structural form and construction method

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3) Dimension and geometry are those of the finished tunnel: width, height, and length, together with levels and gradients and curves. Specified limits may be very narrow or offer a wide range of possibilities.

4) Structural form may be circle, horseshoe, rectangle, or other shape incorporating cast-iron, concrete, brick work, sprayed concrete etc, to carry the loads imposed. The nature of the ground and method of construction influence strongly the structural form.

5) Construction methods range from boring by drilling and blasting, or by tunneling machine, or with or without a shield, to cut and cover in various sequences, and submerged prefabricated tunnels. The choice of method is limited by the ground condition, but also by available resources in the widest sense.

6) Equipment of the completed tunnel include such features as roadway or rail track, lighting, ventilation, decorative and functional finishes, control systems.

All of these things are taken fully into account in the planning and design of the project. It is usually most unsatisfactory and inefficient to make sustainable addition or alterations at a later stage, except where proper provision has been made in the original planning

Tunneling Methods

The adoption of any one of a number of possible methods for tunneling depends on the nature of the soil profile. Soils can be grouped under soft strata or rock. Soft strata may be cohesive soil (clay), or granular soil or mix. Tunneling through soft strata is done by using one of the traditional methods of diving, i.e., excavation by digging or with a tunneling machine. The machine is generally used in very soft layer and clay and prevails in subway construction. Wherever seepage flow is heavy, the operation has to be supplemented by use of compressed air. Occasionally some drilling and blasting is also done, especially in the case of mix soft rock and in laterite types of soil.A number of methods have been developed for tunneling by machine and the choice will generally depend on the type of soil of structure etc.1. Traditional Methods

a. SequencingThe traditional methods of sequencing operation to achieve full profile may be classified as follows:

i. Full face method ii. Top heading and benching method

iii. Bottom heading and stopping methodiv. Drift method, sub classified method into wall plate drift method, side drift method and multiple drift method.

The first three methods are generally used for rocks (aided by blasting) and medium type soils, while the last (iv) is used for soft rocks and disintegrated rock (requiring ground support).

B. Excavation and advancing

These are the methods of making tunnel with simple tools.i. Fore poling Method

The fore poling method is the most commonly used in gravelly cohesion less soil, particularly in running ground for small tunnels, as well as driving headings in some other cases. Fore poles are timber planks with wedged ends which can be driven through the soil.

ii. Tunneling with Liner platesThis is generally used for either forming drifts or headings on medium soft ground. It can also be adopted for small cross-section drifts in running ground, combined with compressed air.

iii. Needle Beam MethodThis method is modification of the liner plate method. It is applicable wherever the roof can stand for a few minutes and the sides for an hour or two as in stiff clay. The full section of the tunnel is broken up into successive portion.

iv. Flying Arch MethodThe flying arch method is similar to the needle beam method except that no beam is used for supporting the liner plates. As the top heading is driven, the liner plates of the arch are supported by trench jacks resting on the bench itself.

v. Shield Tunneling

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The shield tunneling method is used in loose, non-cohesive or soft ground. It is mostly circulars in shape. It can be driven either in free air is under compressed air. The former method is used when the depth of the tunnel is shallow and/or there is not much likelihood of ingress of water, as in clayey soils. The advantage of the shield tunnel is that it permits excavation of soil and erection of primary lining under safe conditions. It also provides better control of ground settlement from above as well as on the sides.

2. Tunneling by tunnel boring machines (TBMs)

These associate back-up systems which can be used to highly automate the entire tunneling process. There are a variety of TBMs that can operate in a variety of conditions, from hard rock to soft water-bearing ground. Some types of TBMs, bentonite slurry

and earth-pressure balance machines, have pressurized compartments at the front end, allowing them to be used in difficult

Some hydropower tunnels of Nepal

conditions below the water table. This pressurizes the ground ahead of the TBM cutter head to balance the water pressure. The

operators work in normal air pressure behind the pressurized compartment, but may occasionally have to enter that compartment to renew or repair the cutters. This requires special precautions, such as local ground treatment or halting the TBM at a position free from water.

S.N. Name of Hydropower Length (m) Shape or Cross section (m or m2)

1 Kaligandaki-A 5 925 Dia. 7.4

2 Marsyandi 7199 Dia. 6.4

3 Kulekhani-I 6233 Dia. 2.3

4 Kulekhani-II 5847.8 Dia. 2.5

5 Modikhola 2071

6 Puwakhola 192 D-shape 2.3*2.3

7 Seti 1555

8 Middle Marsyandi 5210 Dia. 5.4

9 Chameliya * 4418.3 (4 total) 3 D-shape & 1 Horseshoe shape

10 Kulekhani-III* 6924.7 (5 total) O, D & Horseshoe shape

11 Upper Tamakoshi * 9730 (2 total) 29 &7.1

13 Bhotekoshi 3301 D-shape(4*4)

14 Chilime 3069.5 D-shape (3.5*3.75 & 3*3)

15 Indrawati 3000 D-shape(3.25*2.5)

16 Chakukhola 958 D-shape(1.8*2)

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Despite these difficulties, TBMs are now preferred to the older method of tunneling in compressed air, with an air lock/decompression chamber some way back from the TBM, which required operators to work in high pressure and go through decompression procedures at the end of their shifts, much like divers. Until recently the largest TBM built was used to bore the Green Heart Tunnel (Dutch: Tunnel Groene Hart) as part of the HSL-Zuid in the Netherlands. It had a diameter of 14.87 m.

Pipe Jacking, also known as pipe-jacking, is a method of tunnel construction where hydraulic jacks are used to push specially made pipes through the ground behind a tunnel boring machine or shield. This technique is commonly used to create tunnels under existing structures, such as roads or railways.

References

Tunnels planning, design construction, vol.1, J.M.Megaw and J.V.Bartlett Transportation tunnel, S. Ponnuswamy, D. Jhonson Victor Nepal Electricity Authority, Generation, August, 2008, 6th issue www.tunnelwikipedia, the free encyclopedia.htm www.himalhydro.com.np

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Fig. Trolleybus in Kathmandu

WHY AND WHY NOT OF TROLLEYBUS SERVICE IN

KATHMANDU VALLEY

Rudramani Ghimire

061 BME 635

E-VISION 2009

Background

Air pollution is one of the serious problems in the Kathmandu valley, the day by day increasing number of the petroleum vehicles being the major cause for it. Over the last 10 years, the increase in the number of vehicles has rose to a value of 20% per years. This alarming growth of petroleum based vehicles, stirring the environmental balance has warned us to think about the need of zero emission vehicles and their operation in Kathmandu.

Electric vehicles, which use the domestic fuel are one of the zero emission vehicles. There is clear need to promote environmental friendly vehicles.

In context of Nepal, though this trolley bus system is not a new concept, it is a concept that needs vitalization. The Chinese government had set up electric vehicle trolleybus system along the 13 km long from Suryabinayak (Bhaktapur) to Tripureshwor (Kathmandu) in 1975. Now it is not at a working condition.

Introduction:

A trolleybus is an electric vehicle, energy being supplied by the positive and negative stung hung above the road intended for trolleybus operation. Trolley bus are route captive to their over head wires and they can deviate by more than a single traffic lane to either side of the lane from the wires are hung. Most trolleybuses have the limited capability to travel off wire by developing power from the auxiliary power unit or by the traction batteries but modern trolley buses have an auxiliary power unit (APU), which allows the buses to travel off-wire for several blocks and avoid anything blocking their normal route i.e. an excavation in the street or a street fair. Their operation is less flexible than the motor buses but they are more energy efficient, quite and less polluting and long lasting than the motor buses.

The main concern here is to discuss about the why and why not of trolley buses.

Why Trolley Buses?

Trolley buses have significant advantages for operation within the Kathmandu environment, and these can be listed as follows:

Low Noise:

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Whilst diesel buses have become slightly quieter over the last 10 years, there seems little chance that they will ever be made significantly quieter again. The majority of the noise at normal speeds comes from the engine and exhaust. Since a trolleybus will have neither of these noise producers, the noisiest components will be the air compressor, which will only operate intermittently, the air conditioning compressors and fans, and tyres noise, which will only become noticeable at higher speeds.

A large fleet of trolleybuses will therefore result in greatly reduced noise pollution.

What is even more significant is that they could operate thorough housing estates at late hours, and throughout the night, without disturbing residents, in the way that currently occurs.

Reduced Waste:

Due to the intensive use of buses in Kathmandu valley, it is necessary to change engine oil, gearbox oil and fitters at intervals as short as six weeks. Disposal of such waste materials constitutes a sizable environmental burden, although re-use of the oil can ameliorate this problem partially. By contrast, a trolleybus requires very little routine replacement of oils etc. Perhaps the only significant new waste generated is the wearing of the carbon current collector shoe, releasing small amounts of carbon dust, particularly at junctions and points in the overhead wiring.

Improved Performance:

Whilst in the past some trolleybuses, notably those manufactured in China and the former Soviet bloc, were comparatively low powered, and therefore very slow, more recent developments in the electric traction system allow new trolleybuses to out-perform their diesel counterparts. This may not necessarily be in top speed, but certainly in the accelerating phase, and in hill climbing ability, which tends to be more important under Kathmandu conditions, since top speed is rarely if ever required.

For comparison, the recent most powerful diesel buses have an engine power of 224KW (305HP), which is reduced by transmission losses to about 190KW (259HP), diesel engine have only the nearly 30% efficiency and there is a lot of transmission losses also in account. Trolleybus will have a traction motor capacity of 230KW (314HP), which gives about 215KW (293HP) at the drive wheels. It can be seen that the trolleybus can out-perform the diesel equivalent, by a considerable margin.

Smoother Ride:

Diesel buses have irritating vibration due to the reciprocating motion of the cylinder piston system and changing of the multistate gear box. Since trolleybuses do not require any multi-speed gearboxes, they are able to accelerate much more smoothly than a 3 or 4 speed diesel bus, and any erratic application of the accelerator pedal can be electronically smoothed, to avoid discomfort to the passengers.

They also have regenerative, or rheostat braking capability, which in effect replicates the benefit of the hydraulic, or electric , retarder now used by all diesel buses. It provides the driver with a smooth and effortless form of braking, which under normal circumstances avoids the need for any heavy or sudden application of the air brakes.

Unaffected by Oil Price:

A trolleybus will still need some small amount of lubricating oils for the drive axle, chassis lubrication, power steering, etc. Compare this with the total dependence of the diesel bus on oil products, both for it’s primary fuel, and also for large quantities of engine, and gearbox oils. In the contest of the Nepal fluctuating of the oil price is unfortunate, which affect on the political issue too.

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As we have seen recently, oil prices can rise very quickly, and this imposes added cost pressures on all operators of diesel vehicles. Whilst oil supplies are not threatened in the near future, there appears little doubt that future oil reserves will be more expensive to recover, and as demand continues to grow the price of all oil derived products will climb. Nepal has the ability to produce the electricity as required. It has the 2nd largest capacity to produce electricity per person, which is renewable and no risk of shortage. It is the domestic fuel so we can save the money which spent for the purchase of the diesel.

No On-Street Exhaust Emissions:

Diesel vehicle exhaust the unhealthy gases from the tail pipe. Which degrade the health of the people as well erode the metal statue and memorial. Kathmandu is the culturally richest city so we have to preserve metal component of the temple so we need to reduce the tail pipe emission to preserve the aesthetic view of them. Whilst on electrical power there will be some hot air produced by the electrical drive components, this will be minor when compared with either the waste heat produced by a diesel engine and gearbox, or with the waste heat given out from the air-conditioning system.

Why Not the Trolley Buses?

High Capital Cost:

From present indications it appears that an equivalent trolleybus will cost about 70% more than the diesel equivalent. However, the normal working life of trolleybus will be 20 years, as against 14 for a diesel bus. It can therefore be seen that the annual depreciation is only 19% more than for a diesel bus.

The installation of the power supply and overhead wiring network is undoubtedly capital intensive, when compared to normal buses. However, provided the network is intensively used, and can remain in use for a prolonged period, then its costs can be amortized over many years. Overhead wiring appears to have no finite life, and with reasonable maintenance can continue to be used indefinitely. The minimum realistic operational period for a trolleybus system would be 20 years.

Inflexibility:

It is often perceived that trolleybuses can only run in procession, and on fixed routes. However, whilst this was once true, the use of modern, remotely controlled overhead switches mean that it is easily possible for overtaking maneuvers to take place, as well as segregated use of bus stops.

The scope for buses to use alternative roads to avoid major roadwork, fire incidents, etc is already very limited, since most streets not used by buses are already impossible due the obstruction caused by advertising signs.

Another often quoted “problem” is the difficulty of re-routing trolleybuses to go through new development areas, etc. Again this does not apply to most of the main urban bus routes, Where a major road re-alignment is unavoidable, there is always adequate notice, which gives the trolleybus operator sufficient opportunity to modify the overhead network.

As a last resort, trolleybuses could be moved for short distances under the auxiliary power mode to meet a temporary disruption.

Effect on Existing Bus Operations:

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Many people of the Kathmandu valley and nearer are involved in the transportation professional their main source of the income are city buses and micro-buses. Existing buses are replaced from here and it create great problem on the existing buses management. That makes the many people jobless so is the great problem. So the owner should be encouraged to invest on it with great priority. Driver and jobholder can be rejoined on it by providing require training. .

Visual Intrusion of Overhead Wiring:

It is impossible to make overhead wiring for trolleybuses completely invisible, but with good design, and use of high quality components, its visual impact can be reduced. In Nepal electricity is supplied from the overhead wire so we can use the electric poles for the over head wire power supply of the trolleybuses by checking their strength and managing them in the proper way. That reduces the extra pole cost of the trolleybuses.

Conclusion:

Trolleybuses are twice as energy efficient as diesel buses. The operation of trolleybuses results in less air contaminant emissions per km than are produced by internal combustion buses. Trolleybuses are environmentally superior whereas diesel bus emissions cause cancer and are linked to asthma, chronic respiratory disease and heart disease. There is no safe level of diesel exhaust exposure. They perform well in stop-and-go traffic and on busy routes i.e. in the Kathmandu valley, where maximum traffic jam.

Trolleybuses have greater potential to reduce greenhouse emissions in the long-demand we can earn the money from the carbon trading, and it less noisy it can reduce the noise level of the road of the over traffic population area. Trolleybuses have lesser maintenance cost due to the lesser moving component.

Although cleaner than diesel buses, none of the existing and new alternative technologies [CNG, hybrid] can really compete with the trolleybus in terms of the overall toxic emissions profile, load capacity, reliability. Fuel cell buses are currently unproven, but are not likely ever to match the trolleybus in terms of energy efficiency.

Despite these advantages , trolley bus system has several drawbacks as mentioned above . The solutions for these problems need to be sought for inorder to promote trolley bus system and thereby enable the practice of an efficient and eco-friendly transportation system in Nepal.

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Fig. Overhead power supply cable of trolleybus

E-VISION 2009

Background

In Nepal, tea, one of the most widely-consumed beverages in the world, is one of the major cash crops. The area under tea cultivation in Nepal (2004/2005) has more than 15,901 hectares of land. There are more than 85 tea estates providing tea leaves to 38 tea processing factories. Annually more than 12.6 million kg of tea is produced in these factories. The tea produced here are mainly of two types - CTC and orthodox tea. CTC (Cut, Trim & Curl) tea, which is known as black tea, is mostly consumed within the country. Orthodox tea, which is known as hill tea, is export oriented. As per the statistics of the government, currently Nepal is producing 10.94 million kg of the CTC tea and 1.66 million kg of orthodox tea. 90% of the orthodox tea is exported to India and overseas countries, whereas remaining is used for direct consumption and partially for blending purposes in the black tea to impart it with the good flavor. The major hill plantation districts for orthodox tea are Ilam, Tehrathum, Dhankuta and Panchthar. [1]

Tea Production Process

The tea leaves must go through process of Withering, Rolling, Oxidation and Drying for making loose tea. Firstly, two leaves and bud from the tea plant is plucked and collected to wither. The objective of withering is to reduce the moisture in the tea leaf by up to 70%.The tea leaves are laid out on a wire mesh in troughs. Air is then passed through these troughs so that the moisture is removed in a uniform way. This process takes between 12 to17 hours, until the leaves are limp, pliable and will roll well. The tea leaves are then placed into a rolling machine, which rotates horizontally on a rolling table. This action creates the twisted wiry looking tea leaves. During the rolling process the leaves are also broken open, which starts the third process - oxidation.

Oxidation is an extremely important part of tea production. The process of oxidation ultimately creates the different types of tea and contributes to tea's flavor, color and strength. This stage is critical & finalizes the flavor of the tea. If left too long, the flavor will be spoilt. To oxidize tea, the leaves are put into troughs or laid out on tables. Oxidization occurs when enzymes within the leaves react with the air and takes 30 minutes to two hours at about 26oC for completion. It is during this process that the tea leaf changes from green, through light brown to a deep brown. To stop the oxidization process, the tea is passed through hot air dryers. [2]

On an average 100 kg of fresh leaf produces 22.5 kg of dried tea containing residual 3% moisture. The difference of 77.5 kg between the figures represents the moisture evaporated during the process. Of the 77.5 kg, about 20-25 kg is evaporated during withering and around 20-50 kg is evaporated during drying. A leaf particle has to undergo a moisture change from around 70% to 3% during drying. The drying takes place by evaporation of moisture from the surface of tea leaves and migration of moisture from interior of a particle to the surface known as diffusion process. [2]

Drying Process

The drying process is influenced by the temperature of inlet and exhaust air, volume of air, quantity of leaf fed, period of drying. So, these factors should be well accounted before designing the tea drying system. Drying of tea involves both physical and chemical aspects. Temperature, at which tea is dried, has to be selected judiciously.

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SMALL SCALE ORTHODOX TEA DRYING WITH GASIFIER

Bal Mukunda Kunwar 061/BME/607

E-VISION 2009

Too high temperature at the initial stage may cause case hardening and blistering. A faster rate of evaporation may impart the teas an undesirable harshness. On the other hand, too low drying temperature slows down the rate of drying and high temperature oxidation is allowed to proceed for a longer period resulting in a ‘dull’ and ‘soft’ product.

For conventional drier, an inlet temperature between 90-110°C has been found to be satisfactory. Exhaust temperature is equally important as it indicates how much heat has been extracted from the incoming hot air. For conventional drier an exhaust temperature of 50-60°C is advocated as at this range the oxidation of the leaf is brought nearly to a stop. Volume of air for drying depends on two factors – moisture to be removed and temperature selected. If the volume of air is below the normal requirement, the temperature will have to be increased to produce the same amount of heat. Controlling air volume can control the temperature and the capacity of a dryer to a certain extent. Fan or blower is use to control the volume of air. The spread of the leaf should be to a reasonable depth. Overloading the dryer requires higher drying temperature and longer period of drying. In general, finer material should be spread thinner. The thickness of spread of leaf will also depend on the degree of wither as well as inlet temperature index. Time required for drying tea varies with degree of wither, temperature, thickness of spread and volume of air. It is apparent that the two main objectives of drying viz., final moisture content (3%) and arrest of ‘oxidation’ can be achieved even in shorter residence time by increasing the drying rate. [2, 4]

Problem associated with Tea drying in Nepal

Though tea production is good in Nepal, the farmers are facing a lot of problems. In case of orthodox tea the situation is much worse. The overall production of tea leaves in the production area is greater in comparison to the capacities of existing tea factories. There are 15 large scale factories with fixed capacity. This limits the production of tea leaves and surplus production will not fetch proper price. The fresh leaves must be delivered to factory within 12 hrs. But in hilly region due to transportation problem the tea delivery is late. The longer the delivery time more is deduction in price of tea leaves. So, farmers far away from the industries have to produce dry tea on their own. Tea requires special conditions for the preparation and processing, which are not easily available to local farmers at affordable costs. Tea processing has a lot of complication too. Equal importance should be given to each process.

Besides, traditional method of drying using coal, wood, etc in open drying system deteriorates the quality and flavor of the tea. Small contamination with the smoke or undesired flavor destroy the quality of the tea. On the other hand, in hilly region the climatic condition is unsuitable for solar drying. Because of this constraints tea farmers who are living far from the tea industries are not able to produce quality tea, hence they do not get proper price for their products. So, there is a need of good tea drying system for small scale with proper heat source. This system must be able to produce quality tea with preserved flavor. This system must prevent contamination of tea with smoke and other undesired flavor. The production must be high and continuous.

Tea drying system

A tea dryer consists of the dryer, furnace, heat exchanger and a fan. The fan is used to introduce the clean hot air at the bottom of the dryer. In furnace the fuel is burnt. In heat exchanger the heat of the furnace gases is transferred to clean air. In the drying chamber the clean hot air is passed through the leaf and evaporates the moisture therein. Furnace and heat exchanger form one unit known as the stove or air heater. The gasifier is the source of heat energy act as a furnace. The gas is burned in the heat exchanger. The heat generated by the flue gases heats the fresh air passing through the heat exchanger. There is no direct contact between incoming air and burned gas. The heated air is then passed to cabinet by forced circulation. This heated air then dries the tea leaves. [2, 4]

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Gasifier

The gasifier is the source of heat energy in which gasification of biomass occurs. Gasification is a process that converts carbonaceous materials into producer gas by means of thermo chemical reaction of the raw material at high temperatures with a controlled amount of oxygen. Producer gas is the mixture of Carbon monoxide, Hydrogen and Methane which are combustible, together with Carbon dioxide, Nitrogen and Water-vapor, which are non combustible. Gasification is a very efficient method for extracting energy from different types of organic materials. The advantage of gasification is that using the producer gas is more efficient than direct combustion of the original fuel. So, more of the energy contained in the fuel is extracted. Also, it produces less smoke and pollution is also less.

In a gasifier, the carbonaceous material undergoes several different processes at different zone viz; Drying zone, where the moisture is driven out from raw material, Pyrolysis zone, where the carbonaceous particle heats up. & solid biomass decomposed to tar, oils, acids, lighter gases and char in absence of O2, , Reduction zone, where the gasification process occurs as the char reacts with carbon dioxide, steam and hydrogen to produce carbon monoxide, hydrogen and methane, and C ombustion zone, where the pyrolysis products are oxidized into carbon dioxide, carbon monoxide and water vapor which provides heat for the subsequent gasification reactions. On the basis of air movement, gasifier can be divided to; Up-draft gasifier, Down-draft gasifier and Cross-draft gasifier. [3, 4]

Conclusion

From all study and observation between various methods for tea drying, using gasifier as heat source not only helps for uniform flame for heat exchanger, but continuous fuel of multiple nature can be used and drying of tea can be carried out effectively. For higher efficiency,

appropriate exchanger should be with having minimal losses.

References

1. FNCCI,2006

2. http://www.twiningsusa.com/TeaExperience/prepare-manufacture.php

3. http://www.wikipedia.com/gasification.html

4. M.S.BASNYAT, S. O., 1992, “A study on gasifier; A case study on Illam”, M.Sc. Final year project report, Department of Mechanical Engineering.

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LANDFILL GAS: WASTE TO ENERGY

Bikash Shrestha

(061BME609)

Fig: System of landfill gas plant

E-VISION 2009

The trash we toss in the garbage could end up powering our lights, computer and television, because in the world of alternative energy, one man's trash is another man's treasure trove of fuel.

With growing urbanization, environmental sanitation, including solid waste management has become a critical issue. In urban areas, improper dumping is resulting in an accumulation of health and environmental problems. To avoid these problems waste management methods should be practiced. Landfills are one of the most common solid waste management processes. However landfill can create a number of adverse impacts if not managed properly. Landfill gas (LFG) is one of the byproduct of landfill which can cause a lot of harms. However we can utilize LFG to our favor.

Landfill Gas

Landfill gas (LFG) is produced by wet organic waste decomposing under anaerobic conditions in a landfill. The waste is covered and compressed mechanically and by the weight of the material that is deposited from above. This material prevents oxygen from accessing the waste and anaerobic microbes thrive. The microbes turn complex organic compounds in garbage into methane, carbon dioxide, and trace amounts of other compounds. LFG is about 50-55% methane and about 40-45% carbon dioxide, traces of hydrogen sulfide, complex organic compounds and other compounds including nitrogen and oxygen. The exact composition of landfill gas is unique to each location depending on the climate and the garbage profile.

Hazards of Landfill Gas

This LFG slowly released into the atmosphere if the landfill site has not been engineered to capture the gas. Landfill gas is hazardous for these key reasons.

Landfill gas becomes explosive when it escapes from the landfill and mixes with oxygen. The lower explosive limit is 5% methane and the upper explosive limit is 15% methane.

The methane contained within LFG is 21 times more potent as a greenhouse gas than carbon dioxide. Therefore uncontained landfill gas which escapes into the atmosphere may significantly contribute to the effects of global warming.

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Volatile organic compounds (VOCs) contained within landfill gas contribute to the formation of photochemical smog.

Release of the toxic contaminants which can create health problems in local communities. Landfill gas due to presence of hydrogen sulfide has an odor normally associated with rotten eggs / rotten

garbage.

Landfill Gas to Energy

Landfill Gas is a reliable and renewable fuel option that remains largely untapped at many landfills across the world, despite its many benefits. A landfill gas plant is needed for efficient conversion of LFG to energy. A landfill gas plant consists of an extraction system and a utilization system. Extraction System

The gas extraction takes place through vertical perforated pipes and sometimes horizontal

suction pipes. In this way the gas is easily extracted from the very beginning of the gas production, as the gas is sucked out before closure/covering of the landfill. Sometimes an impermeable membrane will cover the landfill, and almost all the gas can then be collected and recovered. Injection of water under the membrane will be necessary in order to maintain a gas production. The gas is sucked out of the landfill by means of a gas pump or a compressor leading the gas to the utilization plant by means of pressure in the transmission pipe. The connection of the single wells to the pump and utilization system can be done in different ways. The most common way, is to connect the wells to a main collection pipe which go around on the landfill.

Utilization System

The gas can be used in a gas boiler for the production of hot water for heating or process heat. Very often the landfill gas is used as fuel in a gas engine, which drives a power generator. There are also other possibilities for using the gas, such as direct use, upgrading to natural gas quality, fuel for vehicles, use in fuel cells, etc.

1. Power production The most known use of the gas is in a gas engine running an electric generator producing power. The normal plant sizes with gas engines produce between 350 and 1200 kW power per engine. In larger plants, in which the power production lies around or above 4 MW, gas turbines are sometimes used, and in very large plants steam turbines can also be used.

2. Combined Heat and Power Plant (CHP Plant)CHP plants compared with only power production are the most efficient system for utilizing the energy from landfills. These plants produce both heat and power output. In principle, there are two types of gas engine plants: spark-ignition engines and dual-fuel engines. Spark-ignition engines can be used for CHP plants with generating capacities from 20 kW to 8 MW. Dual-fuel engines are not made for very small capacities.

3. Boiler SystemsThe second most common use of landfill gas takes place in gas furnaces, in which the gas is used for heating of water in a boiler system. This is a simple system. The heat from some boiler systems is used in greenhouses, either by normal circulation of hot water, or by heating of air that is blown into the greenhouses. This is also a relatively simple and efficient way to use the gas.

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4. Upgrading to Natural Gas QualitySome plants upgrade the landfill gas to natural gas quality. Consequently, the gas can be distributed through the natural gas distribution network.

5. Use of Gas in VehiclesVarious places in the world, for example the USA, Brazil, France, etc., there are plants, in which the landfill gas is compressed and used in either compactors, refuse collection vehicles, buses or ordinary cars.

6. Fuel CellThe landfill gas can also be used in fuel cells. This system has been tested in the USA during some years with a production from 25 kW and up till 200 kW plant.

7. Direct Gas UseSome of the clay mines and cement industries are using the gas directly in the kiln instead of using natural gas. In some cases the landfill gas is used in a mix with natural gas.

8. DryersLandfill Gas is using in drying sludge and canola seeds.

9. Conversions to Methanol and/or Dry Ice Some companies are converting methane from landfills into methyl alcohol or methanol. Some have expressed interest in converting the carbon dioxide in landfill gas to dry ice.

Benefits of Landfill Gas:

Generating energy from LFG creates a number of environmental as well as economical benefits.

1. Reduces Greenhouse gas emissionsLandfill Gas to Energy projects significantly reduces Methane, a potent heat-trapping gas (over 21 times stronger than CO2), emissions from landfills. It is estimated that a Landfill Gas to Energy project will capture roughly 60-90% of the BioMethane emitted from the landfill, depending on system design and effectiveness. The captured methane is destroyed (converted to water and the much less potent CO2) when the gas is burned. 

2. Offset the use of non-renewable resourcesProducing energy from LFG avoids the need to use non-renewable resources such as coal, oil, or natural gas. This can avoid gas end-user and power plant Carbon Dioxide Emissions and criteria pollutants such as sulfur dioxide, particulate matter, nitrogen oxides, and trace hazardous air pollutants.

3. Benefits the local economyLandfill Gas to Energy project generates revenue from the sale of the gas. It also creates jobs associated with the design, construction, and operation of energy recovery systems involving engineers, construction firms, equipment vendors, and utilities or end-users of the power produced.

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4. Creates other indirect benefitsProducing energy from landfill gas also creates indirect benefits like:

Improves the air quality of the surrounding community by reducing landfill odors. Destroys most of the non-methane organic compounds, thereby reducing possible health risks from these

compounds.

Improve safety by reducing explosion hazards from gas accumulation in structures on or near the landfill.

5. Trade under CDMBy simply burning methane we are converting a more potent greenhouse gas to less. Producing energy also reduce the use of petroleum product. So, a lot of carbon is saved which can be traded under Clean Development Mechanism.

Conclusion

Conversion of landfill gas to energy is one of predominately unexploited technology. By exploiting this technology we can help to improve our health, environment and economy. We should endeavor to make our earth better place to live.

References

1. www.LandfillGasToEnergy.com 2. Energy recovery from landfill gas, Willumsen.pdf3. Facts About Landfill Gas, lfgfact.pdf

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Fig: Space Solar Power

E-VISION 2009

Abstract

The solar energy available in space is literally billions of times greater than we use today. The lifetime of the sun is an estimated 4-5 billion years, making space solar power is a truly long-term energy solution. As Earth receives only one part in 2.3 billion of the Sun's output, space solar power is by far the largest potential energy source available, dwarfing all others combined. Solar energy is routinely used on nearly all spacecraft today. This technology on a larger scale, combined with wireless power transmission, can supply nearly all the electrical needs of our planet.

What Is Space Solar Power ?

Space-based solar power (SSP) is the conversion of solar energy into power, usable either in space or on earth, from a location in space such as geosynchronous orbit (GSO). Photovoltaic (PV) would generally be utilized for energy conversion and microwave technology could be applied for wireless energy transmission through space. In space, the sun shines constantly and has greater intensity than on earth. Outside of earth's atmosphere, average solar energy per unit area is in the order of ten times that available on earth and increases as the sun is approached, although there are increased maintenance problems beyond acceptable solar radiation limits.

SSP can generate large amount of electricity. It is estimated that the production of 5 billion watts (5GWh) (equivalent to five large nuclear power plants) would require several square km of solar collectors (weighing approximately 5 million kg) and an earth-based antenna 5 miles in diameter.

Requirements for Space Solar Power

Low-cost, environmentally-friendly launch vehicles: Current launch vehicles are too expensive, and at high launch rates may pose atmospheric pollution problems of their own. Cheaper, cleaner launch vehicles are needed.

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SPACE SOLAR POWER:ENERGY UNLIMITED FROM FICTION TO FUTURE

Bipul Shrestha

061/BME/610

E-VISION 2009

Power transmission: A relatively small effort is also necessary to assess best power transmission from satellites to the Earth’s surface with minimal environmental impact.

Large scale in-orbit construction and operations: To gather massive energy, solar power satellites must be far larger than the International Space Station (ISS). Fortunately, solar power satellites will be simpler than the ISS as they will consist of many identical parts.

Solar power satelliteA solar power satellite, or SPS or Powersat, as originally proposed would be a satellite built in high Earth orbit

that uses microwave power transmission to beam solar power to a very large antenna on Earth. However, the costs of construction are very high, and SPS will not be able to compete with conventional sources (at current energy prices) unless at least one of the following conditions is met.

Sufficiently low launch costs is achieved A determination (by governments, industry,) is made that the disadvantages of fossil fuel use are so large

they must be substantially replaced. Conventional energy costs increase sufficiently to provoke serious search for alternative energy Such a system could have advantages to the world in terms of energy security via reduction in levels of

conflict, military spending, loss of life, and avoiding future conflict over dwindling energy sources.

From Fiction to Future

Space stations transmitting solar power have appeared in science-fiction works like Isaac Asimov's Reason (1941), that centers around the troubles caused by the robots operating the station.

1968: Dr. Peter Glaser introduces the concept of a large solar power satellite system of square miles of solar collectors in high geosynchronous orbit (GSO is an orbit 36,000 km above the equator

1970's: NASA examines the Solar Power Satellite (SPS) concept extensively. 1999: NASA's Space Solar Power Exploratory Research and Technology program initiated.

Recently Japan is trying to experiment with small size power collector India and China are among the very interested countries to harvest this vast source of energy in the near

future.

Fig: Solar power satellite

Components of Solar Power Satellites (SPS) A solar collector, typically made up of solar cells A microwave antenna on the satellite, aimed at Earth One or more paired, and much larger, antennas (rectennas) on the Earth's surface

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Solar energy conversion (solar photons to DC current)

Two methods of converting photons to electricity have been studied, solar dynamic (SD) and photovoltaic (PV).

Solar dynamic uses large reflector to focus sunlight to a high concentration to achieve a high temperature to a heat engine to drive a piston or a turbine which connects to a generator or dynamo. Two heat cycles for solar dynamic are thought to be reasonable for this: the Brayton cycle or the Stirling cycle.

PV commonly known as “solar cells” uses semiconductor cells (e.g., silicon or gallium arsenide) to directly convert sunlight photons into voltage. It is also possible to use Concentrating Photovoltaic (CPV) systems

Wireless power transmission to the Earth

The power could be transmitted as either microwave or laser radiation at a variety of frequencies depending on system design. Whatever choice is made, the transmitting radiation would have to be non-ionizing to avoid potential disturbances either ecologically or biologically if it is to reach the Earth's surface. This established an upper bound for the frequency used, as energy per photon, and so the ability to cause ionization, increases with frequency. Ionization of biological materials doesn't begin until ultraviolet or higher frequencies so most radio frequencies will be acceptable for this.

Problems

Launch costs: 4 GW power station would weigh about 80,000 metric tons (20 kg/kW) or very lightweight design of 4,000 metric tons (1kg/kW) all of which would, in current circumstances, be launched from the Earth. Total launch costs would range between $20 billion (low cost heavy-lift launch vehicle HLLV, low weight panels) and $320 billion ('expensive' HLLV, heavier panels). Extraterrestrial materials from moon or asteroids have been proposed to build solar cells. Space elevators made of carbon nanotubes can make transporting cheaper but it is above recent technologies.

Safety: The use of microwave transmission of power has been the most controversial issue in considering any SPS design, but any thought that anything which strays into the beam's path will be incinerated is an extreme misconception. It is important for system efficiency that as much of the microwave radiation as possible be focused on the rectenna. Outside of the rectenna, microwave intensities would rapidly decrease so nearby towns or other human activity should be completely unaffected. The long-term effects of beaming power through the ionosphere in the form of microwaves has yet to be studied, but nothing has been suggested which might lead to any significant effect.

Solar Power Satellites ( SPS)'s economic feasibility

Current prices for electricity on the public grid fluctuate depending on time of day, but typical household delivery costs about 5 cents/kWh in North America.

If the lifetime of an SPS is 20 years and it delivers 5 GWh to the grid, the commercial value of that power is (5,000,000,000 W)/ (1000 W/kW) = 5,000,000 kWh, which multiplied by $.05 per kWh gives $250,000 revenue per hour. $250,000 × 24 hours × 365 days × 20 years = $43,800,000,000 ($ 43 billion).

By contrast, in the Nepal electricity can cost 13 cents /kWh. This would translate to a lifetime output of $114 billion for power delivered to the Nepal.

Advantages of SSP over Conventional Power System

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Environmental FriendlyIt is a renewable energy source, zero emission, and only generates waste as a product of manufacture and maintenance. Space solar power does not emit greenhouse gases as done by petroleum products, coals and biomass. It does not depend upon scarce fresh water resources, valuable farm land or depend on natural-gas-derived fertilizer. Space solar power will not produce hazardous waste, which needs to be stored and guarded for hundreds of years as in nuclear power. Solar power does not require environmentally problematic mining operations.

Continuous and ultimate source of energySpace solar power is available 24 hours a day, 7 days a week, in huge quantities. It works regardless of cloud cover, daylight, or wind speed. Space solar power can be exported to virtually any place in the world, and its energy can be converted for local needs — such as manufacture of methanol for use in rural places where there are no electric power grids. Space solar power can also be used for desalination of sea water.

Space solar power will provide true energy independence for the nations that develop it, eliminating a major source of national competition for limited Earth-based energy resources. Space solar power will not require dependence on other countries for oil to meet energy needs, enabling us to expend resources in other ways.

New opportunities and explorationSpace solar power can take advantage of aerospace expertise to expand employment opportunities in solving the difficult problems of energy security and climate change. Space solar power can provide a market large enough to develop the low-cost space transportation system that is required for its deployment. This, in turn, will also bring the resources of the solar system within economic reach.

Energy in global winters: Space solar power would be the only means of acquiring direct solar energy to supplement the burning of fossil fuels or nuclear energy sources under the most extreme conditions of a global catastrophic volcanic winter (or similarly, nuclear winter). This could include the massive energy increases necessary to grow food crops and for increased heating requirements under ice age conditions.

Conclusion

Solar energy in terrestrial level is always considered as alternative energy and covers only small portion of total energy utilized. But Space Solar Power can provide energy beyond the possibilities of any other terrestrial sources. The conventional resources are becoming more scarce and the demand of energy is increasing, so we won’t have to wait long to see new power rising above our horizon.

References

http://www.nss.org/

http://www.universetoday.com/

http://en.wikipedia.org/wiki/Space_solar_power

http://en.wikipedia.org/w/index.php?title=Solar_power_satellite

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“HYDROGEN FUEL CELL”

A TECHNOLOGY FOR FUTURE ENERGY GENERATION

Prakash Aryal

061/BME/624

Fig: Schematic Diagram of Hydrogen Fuel Cell

E-VISION 2009

Abstract

In today’s world energy crisis is the major problem with depleting source of conventional organic fossil fuels. A high-tech energy source like nuclear energy is not on everyone’s reach; and is not suitable for small scale and mobile purposes. Thus search for alternative renewable, non-polluting and easily available source of energy is today’s world utmost concern. Hydrogen fuel is one of them having highest possibility of being used as future fuel as it has the highest heating value, non-polluting with only water as byproduct.

As Hydrogen is abundant element on earth it has high energy security. Hydrogen can be produced from a variety of sources:

Traditional: natural gas, gasoline, diesel, propane

Renewable/alternative fuels: methanol, ethanol, landfill gas, bio-gas, methane

Water: using electrolysis, solar or wind power.

Hydrogen requires large storage facilities, low temperatures condition (-2520C) and special transportation system. Explosion hazards are major safety problems in public use of this fuel. Extensive research is being done for easy and safe storage of this fuel.

What Is A Fuel Cell?

A fuel cell is an electrochemical energy conversion device. It produces electricity from various external quantities of fuel (on the anode side) and oxidant (on the cathode side). These react in the presence of an electrolyte. Generally, the reactants flow in and products flow out while the electrolyte remains in the cell. It will produce energy in the form of electricity and heat as long as fuel is supplied.

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Fig: Design of Hydrogen Fuel Cell

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In principle, a fuel cell operates like a battery. Unlike a battery, a fuel cell does not run down or require recharging. Many combinations of fuel and oxidant are possible. A hydrogen cell uses hydrogen as fuel and oxygen as oxidant. Other fuels include hydrocarbons and alcohols. Other oxidants include air, chlorine and chlorine dioxide. A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat.

Hydrogen fuel is fed into the "anode" of the fuel cell. Oxygen (or air) enters the fuel cell through the cathode. Encouraged by a catalyst, the hydrogen atom splits into a proton and an electron, which take different paths to the cathode. The proton passes through the electrolyte. The electrons create a separate current that can be utilized before they return to the cathode, to be reunited with the hydrogen and oxygen in a molecule of water.

A fuel cell system which includes a "fuel reformer" can utilize the hydrogen from any hydrocarbon fuel - from natural gas to methanol, and even gasoline. Since the fuel cell relies on chemistry and not combustion, emissions from this type of a system would still be much smaller than emissions from the cleanest fuel combustion processes.

Fuel cell design

In essence, a fuel cell works by catalysis, separating the component electrons and protons of the reactant fuel, and forcing the electrons to travel through a circuit, hence converting them to electrical power. The catalyst is typically comprised of a platinum group metal or alloy. Another catalytic process takes the electrons back in, combining them with the protons and the oxidant to form waste products (typically simple compounds like water and carbon dioxide).

In the hydrogen–oxygen proton exchange membrane fuel cell (PEMFC) design, a proton-conducting polymer membrane, (the electrolyte), separates the anode and cathode sides.

On the anode side, hydrogen diffuses to the anode catalyst where it later dissociates into protons and electrons. The protons are conducted through the membrane to the cathode, but the electrons are forced to travel in an external circuit (supplying power) because the membrane is electrically insulating. On the cathode catalyst, oxygen molecules react with the electrons (which have traveled through the external circuit) and protons to form water — in this example, the only waste product, either liquid or vapor.

In addition to this pure hydrogen type, there are hydrocarbon fuels for fuel cells, including diesel,

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methanol (see: direct-methanol fuel cells) and chemical hydrides. The waste products with these types of fuel are carbon dioxide and water.

To deliver the desired amount of energy, the fuel cells can be combined in series and parallel circuits, where series yield higher voltage, and parallel allows a stronger current to be drawn. Such a design is called a fuel cell stack. Further, the cell surface area can be increased, to allow stronger current from each cell.

Benefits of Hydrogen Fuel Cell

No other energy generating technology carries the combination of benefits that fuel cells offer. These benefits include:

Engine Type H2O

g/mile

CO2

g/mile

CO g/mile NOx g/mile HC

g/mile

Gasoline Passenger Car1 176.90 415.49 20.9 1.39 2.80

Gasoline Light Truck1 N/A 521.63 27.70 1.81 3.51

Methanol FCV2 113.40 68.04 0.016 0.0025 0.0034

Hydrogen FCV2 113.40 0.00 0.00 0.00 0.00

Source: 1 2000 U.S. EPA Average Annual Emission for Passenger Cars and Light Trucks

2 Calculations from Desert Research Institute

Low to Zero EmissionsA fuel cell running on pure hydrogen is a zero-emission power source. Some stationary fuel cells use natural gas or hydrocarbons as a hydrogen feedstock, but even those produce far less emissions than conventional power plants. Fuel cells are also very quiet, which reduces noise pollution.

TransportationFuel cell vehicles are the least polluting of all vehicles that consume fuel directly.

Fuel cell vehicles operating on hydrogen stored on-board the vehicles produce zero pollution in the conventional sense. Neither conventional pollutants nor green house gases are emitted. The only byproducts are water and heat. The simple reaction that takes place inside the fuel cell is highly efficient. Even if the hydrogen is produced from fossil fuels, fuel cell vehicles can reduce emissions of carbon dioxide, a global warming concern, by more than half.

High Efficiency In large-scale building systems, these fuel cell cogeneration systems can reduce facility energy service costs by 20% to 40% compared to conventional energy service. Systems fueled by hydrogen can consistently provide more than 50 percent efficiency. Even more efficient systems are under development.

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In combination with a turbine, electrical efficiencies can exceed 60 percent. Fuel cell passenger vehicles are expected to be up to three times more efficient than internal combustion engines, which now operate at 10 to 16 percent efficiency.

High Reliability/High Quality PowerA fuel cell system running on hydrogen can be compact, lightweight, has no major moving parts and do not involve combustion, in ideal conditions they can achieve up to 99.9999% reliability. Fuel cells offer clean, high quality power, crucial to an economy that depends on increasingly sensitive computers, medical equipment and machines. Fuel cells can be configured to provide backup power to a grid-connected customer, should the grid fail. They can be configured to provide completely grid-independent power or can use the grid as the backup system.

Fuel FlexibilityMost fuel cells run on hydrogen and will continue to generate power as long as fuel is supplied. The fuel cell doesn't care where the hydrogen comes from, so a fuel cell system that includes a "fuel reformer" can generate hydrogen from diverse, domestic resources including fossil fuels, such as natural gas and coal; alcohol fuels, such as methanol or ethanol; from hydrogen compounds containing no carbon, such as ammonia; or from biomass, methane, landfill gas or anaerobic digester gas from wastewater treatment plants. Hydrogen can also be produced from electricity from conventional, nuclear or renewable sources such as solar or wind.

SecurityHydrogen can be produced from domestic sources, eliminating the need to import foreign oil. Because they don't have to be attached to the electric grid, fuel cells allow the country to move away from reliance on high voltage central station power generation which are the most likely terrorist targets in any attempt to cripple the energy infrastructure.

Modularity/Scalability/Flexible SitingThe beauty of fuel cells is their versatility - since they are scalable, fuel cells can be stacked until the desired power output is reached. Larger fuel cells can be linked together to achieve megawatt outputs. Fuel cells are quiet, which allows for siting close to business or residences. They are also durable and rugged, so they can withstand any terrain or weather conditions.

Lightweight, Long-lasting Battery Alternative Fuel cells are being developed for portable electronic devices such as laptops, cellular phones, etc. Fuel cells are providing a much longer operating life than a battery would, in a package of lighter or equal weight per unit of power output. Fuel cells also have an environmental advantage over batteries, since certain kinds of batteries require special disposal treatment. Fuel cells provide a much higher power density, packing more power in a smaller space.

Application of Fuel Cell

Remote Location Fuel cells are very useful as power sources in remote locations, such as spacecraft, remote weather stations, large parks, rural locations, and in certain military applications.

Heat and power supply for domestic purposeA new application is micro combined heat and power, which is cogeneration for family homes, office buildings and factories. This type of system generates constant electric power (selling excess power back to the grid when it is not consumed), and at the same time produces hot air and water from the waste heat

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StationaryIn hospitals, nursing homes, hotels, office buildings, schools, utility power plants - either connected to the electric grid to provide supplemental power and backup assurance for critical areas, or installed as a grid-independent generator for on-site service in areas that are inaccessible by power lines.

Telecommunications With the use of computers, internet, and communication networks steadily increasing, there comes a need for more reliable power than is available on the current electrical grid, and fuel cells have proven to be up to 99.999% (five nines) reliable.

Landfills/Wastewater Treatment Plants

Fuel cells currently operate at landfills and wastewater treatment plants, proving themselves as a valid technology for reducing emissions and generating power from the methane gas they produce.

TransportationDifferent vehicles like two wheelers, cars, buses etc, using petrol or diesel as fuel can be operated using fuel cell after slight modification in the design.

Trains - Fuel cells are being developed for mining locomotives since they produce no emissions. An international consortium is developing the world’s largest fuel cell vehicle, a 109 metric-ton, 1 MW locomotive for military and commercial railway applications.

Planes - Fuel cells are an attractive option for aviation since they produce zero or low emissions and make barely any noise. Companies like Boeing are heavily involved in developing a fuel cell plane.

Portable Power Fuel cells can provide power where no electric grid is available and they are quiet which reduces noise

pollution.

Micro Power

Consumer Electronics- Fuel cells will change the telecommuting world, powering cellular phones, laptops and palm pilots hours longer than batteries.

Base load power plantsThe hydrogen fuel cell power plants for base load can be established for fulfilling continuous demand of

the electricity.

Conclusion From the above described benefits and possible application areas of hydrogen fuel cell, we can say that hydrogen is sure to replace conventional fuel as major fuel in coming days. Special precautions should be taken in handling and storage of hydrogen fuels. Hydrogen fuel cell is very versatile in nature having wide fields of applications so research and development of this fuel cell must be promoted worldwide.

References

www.fuelcells.org

www.en.wikipedia.org/wiki/Fuel_cell

www.howstuffworks.com/fuel-cell.htm

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CANTEEN QUALITY SURVEY

Nabin Shrestha (061 BME 618)Prabha Sharma (061 BME 622)

E-VISION 2009

AbstractThis paper presents the findings on the survey of canteen quality conducted at Institute of Engineering (IOE), Pulchowk Campus, Tribhuwan University (TU) Nepal. The data were collected by written questionnaires distributed to the respondents. The mean satisfaction levels were calculated. The overall mean satisfaction level of the students was found 3.46 based on 5 point rating scale (1-Excellent, 2-Very good, 3- Good, 4-Bad, 5-worst).The study indicated the quality of the canteen on various parameters that the students were or weren’t satisfied with. BackgroundThere are four canteens in Institute Of Engineering, Pulchowk which provide services to the students as well as to the staffs of the College. Some of them also provide the meals. But every time there is always some tone of dissatisfaction from the students. Thus, in the prospect of Quality Management, we studied the quality of food provided by the canteens by the students’ survey.

The most common problems of the canteens were found to be uncomfortable seats, lack of proper air circulation, untimely service and unmanaged interiors.Purpose To find the factors which are contributing to reduce the quality To find the satisfaction level of the students To find the hygiene factor of the canteen

Methodology All the canteens were visited to collect the menus available. Survey questions were prepared (about 180 sets of questions) and distributed to the students of every faculty. Survey Questions’ responses were collected (only 114 responses were obtained). Analysis of the collected information was carried out.

Assumptions of the study:Canteen A: Canteen at architect departmentCanteen E: Canteen opposite to central libraryCanteen F: FSU canteenCanteen H: Hostel messLimitations of the study : The quality of Tiffin items only was checked. Due to time limit internal satisfaction level of respondents could not be surveyed. Views of canteen proprietors and staffs of the campus couldn’t be taken.

Research MethodologyPopulation and sample:The target population for this study was 1584 students studying at bachelor level in Institute of Engineering, Lalitpur. About 180 students (11.36%) were expected to participate in survey. But only 114 students responded which covers about 7.2 percent of the total students.

Instrumentation:

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Questionnaires containing 11 questions were distributed for the study. 5 grades of satisfaction levels (1-Excellent, 2-Very good, 3- Good, 4-Bad, 5- Worst) were used considering 11 parameters identified by our team and our instructor Er. Guna Raj Poudel.

Data Collection Process:About 6 or 7 students from each class were given questionnaires. After about one week the questionnaires along with their responses were collected.Data Analysis:Data recording and analysis were done by the team members. Results of the study:From the survey, it was found that 85.96% of the total students take Tiffin at the college canteen. 92.86 % of 2064 batch, 91.43 % of 2063 batch, 88.89% of 2062 batch and 72.73 % from 2061 batch students take Tiffin at the college canteen (Refer tables 1 and 2). The trend showed that there is certain dissatisfaction in taking Tiffin at the college canteen. The other causes for this trend may be that students get information about the hotels and other canteens located outside the college premises which provides the better qualitative food. At average, 40.35% of students

take Tiffin in college canteen only for 4 or 5 days. Following it, 23.68% take for 6 days, 20.18% take for less than 3 days, 12.28% take for 7 days and 3.51% doesn’t take Tiffin at all in college

Canteen.

The most preferred canteen is canteen E by 45.54% of students. Similarly, canteen F by 33.03%, canteen H by 15.18% and canteen A is only by 6.25%. Table 3 shows the preferred canteen by the respective batches. 35.74% of students responded that taste affects the quality most. Similarly 28.83% responded price, 21.62 responded other factors, 8.11% responded manner of the staffs and 6.30% responded delivery service affects the most in the quality provided by the canteen. The batch wise rating scales are shown in table 4.

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The students are not getting the type of food they preferred in the canteen of IOE. Only 25.23% of students expressed their view that they are getting their preferred food in the IOE canteen but 74.77% of students gave the negative reply. The detail results are shown in table 5.

Talking about the drinking water facility, 88.50% of students agreed that drinking water should be provided by the canteen whenever required. The batch wise analysis is shown in table 6.

Though students take the Tiffin in the college canteen, their main complain is that they don’t get the drinking water facility easily in canteens. 47.32% of students get drinking water only 25% to 50% of time, 25% get more than 75% of time, 8.93 % always get drinking water whereas 18.75% doesn’t get drinking water at all during their visit to canteen. The details are shown in table 7.

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According to the 5 grade scale (refer table 8 and 9), the hygienic condition of food in the canteen is near about bad and is rated 3.775853, taste and price depending on quality are slightly above good and is rated 3.263573 and 3.225092 respectively. Table layout is rated near to bad and is 3.67733. Access to entry and exit is slightly above good and is 3.121922. Location of canteen is rated between very good and good and is 2.639674. Manner of canteen staff is rated slightly above good and is 3.105714. Air circulation in the canteen is rate between good and bad and is near to bad having rated 3.621871. Sanitary facility is near to bad and is rated as 4.006684. Delivery time is rated between good and bad and is nearer to good and is 3.225618. Lighting aspects is rated between good and bad and is rated as 3.30623. Canteen cleanliness is rated 3.996785 which is nearly bad. Furniture conditions is rated 4.019971 which is slightly above bad.

Out of the different parameters provided by the survey team, it was found that the furniture condition was rated 4.019971 and location was provided 2.639674. It means students have got great dissatisfaction in the furniture condition the most and satisfaction in the location of the canteen of IOE. Other parameters were rated between these two.

Conclusion:The study showed that the overall quality level of the canteen is not satisfactory (3.46). There is a high gap to improve the quality level of existing canteen from good to excellent. Canteens are for the students to fulfill their appetite. One of the challenges for the canteen proprietors is

to fulfill the need of the students by providing quality food in economical price in this competitive environment.

References:1. E-Vision An Annual Engineering Journal 2006, Vol. 42. Small Business Success Through TQM, Terry Ehresman, TATA McGraw Hill Publishing Company Ltd, Delhi

(1996)

99

DEMING’S WAY

Ravi Shah 061BME632

E-VISION 2009

The ultimate curse is to be a passenger on a large ship, to know that the ship is going to sink, to know precisely what to do to prevent it, and to realize that no one will listen! This is the curse that has been visited for a quarter of a century on W. Edwards Deming, revered in Japan as the Father of Quality Control, the man who taught the Japanese how to produce goods of high quality at low cost.

Deming had taught the Japanese that higher quality meant lower cost, an idea foreign to most American managers. He foresaw what would happen. Japanese entrepreneurs, observing a successful business in America, such as textiles, steel, autos or consumer electronics to name but a few could study the products, reverse engineer them, and produce them at lower cost and higher quality. If one nation has access to another's technologies and is better at the arts and sciences of mass production, it follows that the first nation will invade the markets of the second. It is just a matter of time.

Too many people believe that Deming merely teaches simple statistical quality control. They miss the point. American managers travel to Japan, marvels at the behavior of the factory workers, and conclude that it is something inherent in the Japanese culture. They come home convinced that it is not their fault. They blame their problems on the American worker, on taxes, on government regulation, on the decay in society, in short, on anything except their own managerial philosophies.

What Is Deming's Way?

Consider a trucking firm managed by a man educated according to current management methods taught in our schools of business management. He will consider his job to be to run the company as profitably as he can and to expand its business. To do so he may call on the best consultants he can get to help him design the best possible system. He may set up work standards for the drivers and institute computer-based procedures to keep track of the performance of the drivers, trucks, and dispatchers. He will study his markets and their opportunities. And he will keep extensive records of income and expenses, ever on the alert for opportunities to profit.

Of course, he will not be able to do these things alone, and as his organization grows, he will institute methods to see that his desires for efficiency and performance are carried out. Perhaps he will adopt management by objectives and teach it to his subordinates. He may assign as much as 5 percent of his work force to data gathering and performance monitoring, ever searching for possible profit opportunities.

In short, his idea of a good manager is one, who sets up a system, directs the work through subordinates, and by making crisp and unambiguous assignments develops a basis to set standards of performance for his employees. He sets goals and production targets for his people. He rates the employees as objectively as he can; sometimes even calling on consultants to help him do so. He identifies poor performers and gives them further education to meet the work standards, or he replaces them He hopes thereby to create the most efficient system possible.

Contrast this with the behavior of a manager who follows Deming's way. This manager sees his job as requiring him to provide a consistency and continuity of purpose for his organization and to seek ever more efficient ways to meet its purpose. For him, making a profit is necessary for survival but is by no means the main purpose of his organization. His view of the purpose of his organization is to provide the best and least-cost transportation system for his customers and continuity of employment for his workers He does not view the concepts of "best" and "least-cost" as contradictory.

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He will consider that he and the workers have a natural division of labor. They are responsible for doing the work within the system, and he is responsible for improving the system. However, he realizes that the potentials for improving the system are never ending so he does not call on consultants to teach him how to redesign the "best" system for he knows that it doesn't exist. Any system can be continuously improved on. He knows that the only people who really know where the potentials for improvement lie are the workers themselves. He knows that the system is subject to great variability. Traffic conditions change, trucks break down, shipping docks are not always ready to discharge or receive goods, and mistakes are made in routing or addressing. There are countless ways for the system to go wrong and out of control, decreasing quality and increasing cost. He knows that these ways occur randomly. To make it possible for him and the workers to work together, he knows they must regard the system in the same way and speak a common language. Therefore he learns elementary statistics and teaches it to the workers, engaging an expert consultant in statistics if necessary to help him and the workers when they come to a problem beyond elementary statistics. All of his employees learn to keep their own statistics. Truck drivers keep track of how long they have to wait at docks and study the circumstances at each event. They develop their own control charts and look for trends, for correlations with other events, usually events beyond their control. The drivers meet with each other and sometimes with the dispatcher and compare notes. They keep data on the performance of their trucks and discuss their statistical charts with the purchasing agent and each other. Based on these data the manager, who is responsible for the system, makes the changes, and the workers, based on their statistical information, and help him to learn how effective the changes have been. When the manager instructs the purchasing agent to buy on "quality," not just on first cost, the purchasing agent has the information from the drivers with which to do just that, and to demonstrate that he has done so. Everyone in the system is involved in studying it and proposing how to improve it. Everyone spends about 5 percent of their time in this pursuit. No one spends 100 percent of the time, except the company statisticians. The employees will see the setting of work standards as a dumb idea since it inhibits their ability to improve the system. They will not need to "manage by objectives" because they will be engaged in consistently redefining their objectives themselves and recording the performance of the system.

Under Deming's way, the manager understands that he needs the workers not only to do the work but to help him to improve the system. Thus he will not regard them simply as robots made of flesh and bone, but he will rather consider them as thinking, creative human beings. No one will have to teach him to be nice to people. He will not try to motivate them with empty slogans, such as "Zero Defects!" Because they will be measuring and counting the defects themselves and helping him to remove them, there will be no need for the slogans. He will not ask them to sign pledges to be polite to customers. Nor will he select the "Polite Trucker of the Week.”Instead, he and they will have been studying the records of repeat orders and asking what they can do to improve the statistics.

From time to time he asks for volunteers from his work force to take time out to interview customers and vendors, to understand what they want or can supply to provide better service. They report back to him and the rest of the work force on what they have found, statistically analyzed.

In short, the Deming-trained manager will have a natural basis for building a team and will not have introduced adversarial relations.

Under currently taught methods of management it is presumed that the relation between boss and worker is inherently adversarial. The result is that bosses who wish to fit the understood image must be careful not to develop too intimate a relationship to the worker, lest they lose their objectivity in judging and rewarding performance.

Deming's way is therefore more than just attention to quality control. It is a managerial philosophy for achieving lower cost and higher quality. And it works not only in the factory, but in hospitals, in service industries, and even in the offices.

It is in seeing how a changed managerial self-image could lead to such phenomenal successes that Deming had one of those brilliant flashes of insight that few of us are privileged to have. As Newton with the apple (gravity), Einstein with relativity, Freud with the subconscious, Deming saw a new way for management.

References:

‘Deming’s way’, Myron Tribus, Massachusetts Institute of Technology

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1. 061/BME/601Name: Ambish Kaji ShakyaNickname: AmbushPhone no: 9841578329Address: Ombahal, KathmanduEmail address: [email protected] of interest: Automobile, Hydropower.Final year project: Design and fabrication of a kitchen waste based biogas plant and testing with different feed materialsIOE in one word: Independent Memorable moments: Hanging out with friends outside CIT Building, Kali-Gandaki tour, Kakani picnic, TES classMy words: Do good, be good, think good.I’m unique coz: I’m attentive and always smiling at every moment.Motto: Stay forward, always be ambitious towards your work and effort.

2. 061/BME/602Name: Amit RegmiNickname: EinsteinPhone no: 9841549387Address: Ghorahi, DangEmail address: [email protected] of interest: MechatronicsFinal year project: Design and fabrication of sticker labeling machineIOE in one word: Extraordinary Memorable moments: Losing 3rd year Cricket tournament and mobile.My words: The future belongs to the people who see possibilities before they become obvious.I’m unique coz: I’m altruist.Motto: Test of courage comes when we are in the minority and the test of tolerance comes when we are in

the majority.

3. 061/BME/603Name: Anil KunwarNickname: Anil SirPhone no: 9849085749Address: Palung Mainadi V.D.C.-4, PalpaEmail address: [email protected], [email protected] of interest: Research and development in mechanicsFinal year project: Design and fabrication of Bucket Wheat Dehusking MachineIOE in one word: Vast technologyMemorable moments: Entrance examination, classes and laboratories,

Janaandoaln , hostel days.My words: If there were 75 Pulchowk Campuses in Nepal, the rate of development of Nepal would have been

75 times greater than now.I’m unique coz: some of my thinking and doing are intuitively unique.Motto: Love everyone, believe in few and hate nobody.

4. 061/BME/605Name: Arjun BhattaraiNickname: HitlerPhone no: -Address: Lions Chowk, Ngt, ChitwanEmail address: [email protected] of interest: MPFinal year project: Study on the production of briquettes from pine needleIOE in one word: Heaven Memorable moments: Anytime happy, good with CNG, time spent with energy less ‘Maila’

‘Daku’ Sir ko guf, Purna maila ko style and his guf, Chiya Pasal, My words: Anyhow, we have to become successful. Do all things if you are satisfied.I’m unique coz: I’m unique.Motto: Be happy, go ahead.

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5. 061/BME/606Name: Ashim DahalNickname: NakulPhone no: 9841743416Address: Mulpani, KathmanduEmail address: [email protected] of interest: AeronauticsFinal year project: Performance evaluation of micro-francis turbineIOE in one word: Dream Memorable moments: Visit to Malaysia during Robot Competition, Cards played in

2nd year, ‘Kakani picnic ko alcohol dance’.My words: In this divine place I could purify my insight from crude immature thought.I’m unique coz: I’m always happy.Motto: Do your best, God will do the rest.

6. 061/BME/607Name: Bal Mukunda Kunwar Nickname: BalPhone no: 9841428924Address: Itram-8, Birendranagar, SurkhetEmail address: [email protected] of interest: A/C, AeronauticalFinal year project: Design and fabrication of gasifier tea drying systemIOE in one word: DelinquentMemorable moments: Kakani & Nagarkot picnic, Gorkha tour, Cricket tournamentMy words: Keep breathing everything gonna be rightI’m unique coz: I am mysteriousMotto: Enjoy the life

7. 061/BME/609Name: Bikash Shrestha Nickname: Potter BhaiPhone no: 9841428923Address: Silgadhi, Doti-2Email address: [email protected] of interest: EnergyFinal year project: Design and fabrication of gasifier tea drying system IOE in one word: JoyfulMemorable moments: Gorkha tour, Dance of Nagarkot picnicMy words: Dream what you want to dream, Go where you want go,

Try to be who you really are. I’m unique coz: -Motto: Live and let live

8. 061/BME/610Name: Bipul ShresthaNickname: BipulPhone no : 9841509814Address: Phungling-4, TaplejungEmail address: [email protected] of interest: Sports, Computer, Hangouts and hangovers.Final year project: Design and fabrication of gasifier tea drying systemIOE in one word: TransformerMemorable moments: Football game with electronics, Kakani picnic, Gorkha tour.My words: Take every event as opportunity to learn new things. Never take it

personal coz nobody will remain same. It’s up to you to make difference.I’m unique coz: I have booster to do anything good at short time.Motto: Life’s good.

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9. 061/BME/611Name: Dave Shrestha Nickname: -Phone no: 9741015299Address: Koteshwor Email address: dave.daveshrestha@gmail .comField of interest: EntrepreneurshipFinal year project: Solar Hybrid Tunnel DryerIOE in one word: Irresponsible Memorable moments: Gorkha tour, night in our class My words: -I’m unique coz: -Motto: -

10. 061/BME/612Name: Guru Prasad ChaudhariNickname: GuruPhone no: 9803397401Address: Harion-2, SarlahiEmail address: [email protected] / [email protected] of interest: Mechanical DesignFinal year project: Refining of lubricating oilIOE in one word: FunMemorable moments: Renewable energy tour ’Gorkha’My words: Success at every costI’m unique coz: -Motto: To see others from the top

11. 061/BME/613Name: Jatin Man AmatyaNickname: JagguPhone no: 9841280480Address: Pulchowk, LalitpurEmail address: [email protected] Field of interest: Renewable Energy, Management.Final year project: Design and fabrication of moon buggy.IOE in one word: South ParkMemorable moments: Chitwan tour, playing ‘chhungi’ infront of CIT, College tours, etc.My words: God bless AmericaI’m unique coz: I love Chelsea.Motto: Live Chelsea, eat Chelsea, and drink Chelsea.

12. 061/BME/614Name: Kundan Lal Das Nickname: KundiPhone no: -Address: Shreepur, BirgunjEmail address: [email protected] of interest: SportsFinal year project: Design and fabrication of a kitchen waste based biogas plant and

testing with different feed materialsIOE in one word: DestinyMemorable moments: On the elephant!My words: Be good, do good.I’m unique coz: No one knows me well.Motto: Live and let live.

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13. 061/BME/615Name: Manika ManandharNickname: -Phone no: 9841513525Address: Nayabazar, KathmanduEmail address: [email protected] of interest: Energy, Environment.Final year project: Multipurpose application, socio-economic and technical

aspect of rice husk.IOE in one word: SenescenceMemorable moments: Gorkha tour, Kali-Gandaki tour, Picnic at Lakure-BhanjyangMy words: -I’m unique coz: I know what life is and what I’ve to do.Motto: You can get what you have by giving it away.

14. 061/BME/616Name: Manoj ChandNickname: MannuPhone no: 9849087132Address: Kanchanpur, MahendranagarEmail address: [email protected] of interest: Engineering, management and modeling.Final year project: Designing, fabrication and testing of Aircraft Travel Board

Certification DeviceIOE in one word: BestMemorable moments: With friends and family.My words: Try to enjoy each moment of life if possible.I’m unique coz: I think coz of tall and handsome.Motto: Never give up hope.

15. 061/BME/617Name: Min Narayan ShresthaNickname: MinuPhone no: 9849087132Address: Dulegaunda-8, Tanahun, GandakiEmail address: [email protected] of interest: Cycling, riding bike, table tennis, badminton.Final year project: Multi-crop seed-cum fertilizer planter driven by bullockIOE in one word: ParliamentMemorable moments: Operating lathe machine for first time in Mechanical workshop.My words: Go ahead to meet your destination-never be disturbed by throne

on you way, clear it and go ahead.I’m unique coz: I enter every class after teacher has entered.Motto: To be a successful Hydropower Designer

16. 061/BME/618Name: Nabin ShresthaNickname: CRPhone no: -Address: Khanlthoke VDC-3, KavreEmail address: [email protected] of interest: Heavy equipment and quality controlFinal year project: Design and fabrication of Institutional Metallic Cooking StoveIOE in one word: TheatreMemorable moments: Picnic at Kakani, Tour at Gorkha, Pokhara, attachment at

Panchakanya, all four years as C.R. of mechanical batch.My words: Balance between yours and other’s wishes.I’m unique coz: I’ve been C.R. from UKG to Bachelor.Motto: Understand this world.

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17. 061/BME/619Name: Nilesh PradhanNickname: NiluPhone no: 9841579959Address: Kupondole, LalitpurEmail address: [email protected] of interest: Automobile, Renewable EnergyFinal year project: Design and fabrication of ‘moon buggy’IOE in one word: YouthMemorable moments: CountlessMy words: If you always do what you have always done, you will always get

what you always got.I’m unique coz: I jump!Motto: Move on.

18. 061/BME/620

Name: Param Chandra AdhikariNickname: Maaila, MP, PanditPhone no: 9803020544Address: Kupondole, SanepaEmail address: [email protected] of interest: MPFinal year project: Study on production of briquette from pine needleIOE in one word: Egg BoilerMemorable moments: KECian, Daku’s home, Get together just before FSU election, Welcome party, Bike sikako, 064

Fagu Purnima, Garon Gurung @ CES.

My words: There is no time in space, we’ve created it.I’m unique coz: I don’t get things out of my heart easily.Motto: To get fully satisfied of my life during my last breath.

19. 061/BME/621Name: Pitambar PaudelNickname: PituPhone no: 9841783203Address: Rupsepani, Dhainbung -8, RasuwaEmail address: [email protected] of interest: HydropowerFinal year project: Multi-crop seed-cum fertilizer planter driven by bullockIOE in one word: WonderfulMemorable moments: Jana Andolan-2, Gorkha tourMy words: I have only sentences, no words.I’m unique coz: I’m fat.Motto: Enjoy every moment of life.

20. 061/BME/622Name: Prabha SharmaNickname: PrabhaPhone no: 9841873760Address: Tucktukiya, Makrahar-9, RupandehiEmail address: [email protected] of interest: Automobile, Management.Final year project: Design and fabrication of Institutional Metallic Cooking StoveIOE in one word: Better.Memorable moments: All final cricket matches and picnics.My words: Every successful person has a painful story and every painful

story has a successful ending.I’m unique coz: I’m optimistic.Motto: Be powerful.

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21. 061/BME/623Name: Pradeep Man Shrestha Nickname: -Phone no: 9741031601Address: E khacheen, LalitpurEmail address: [email protected], [email protected] of interest: Final year project: Design and fabrication of ‘moon buggy’IOE in one word:Memorable moments: Lots of moments are memorable…, frens of Mechanical, Civil,

Archi, events & tours, seniors and juniorsNilesh ko didi

My words: Live in love & harmony I’m unique coz: I am on timeMotto:

22. 061/BME/624Name: Praksh AryalNickname: DonPhone no: 9841611507Address: Gwadi-2, GulmiEmail address: [email protected], [email protected] of interest: Politics, R and D of new technology, Internet surfing, etc.Final year project: Design and fabrication of gasifier tea drying systemIOE in one word: Platform Memorable moments: Picnics, tours, Farewell and Welcome, Canteen, labs, etc.My words: Great people do not do different things but they do things differently.I’m unique coz: I’m open-minded, friendly and helpful.Motto: To be a leader for the ‘Technical Revolution in Nepal’.

23. 061/BME/625Name: Prameet Ranjan JhaNickname: HajariPhone no: 9841264461Address: Janakpur-14Email address: [email protected] of interest: Cricket, party with friends.Final year project: Design and fabrication of sticker labeling machineIOE in one word: Must visit place.Memorable moments: Gorkha tour, Kakani picnic, ‘Taas kheleko class ma’ attachment,

losing 2nd and 3rd year cricket finalsMy words: Don’t ever provoke anyone’s ego and never introduce the useful persons you knew to others.I’m unique coz: I’m single piece.Motto: Stick to the basics.

24. 061/BME/626Name: Prashant KarnaNickname: Kale, NeoPhone no: -Address: Lahan, SirahaEmail address: [email protected] of interest: Cricket.Final year project: Design and fabrication of sticker labeling machineIOE in one word: Good.Memorable moments: ‘Crying Pramit’ at KakaniMy words: Be ‘bindas’I’m unique coz: I don’t think so.Motto: Pramit knows.

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25. 061/BME/627Name: Purna GhimireNickname: Purne, TalwarPhone no: 9841743420Address: Prithvi Chowk, PokharaEmail address: [email protected] of interest: MPFinal year project: Comparativ e performance evaluation of micro-Francis turbine.IOE in one word: Heaven Memorable moments: Always MP, Kedar Dai ko café, Hitler re Jungali ko room,

class bunk gareko, 7th semester ko result ko night.My words: Every dream will be fulfilled in IOE.I’m unique coz: I’m Purna, nobody else.Motto: Be positive, think positive, do as you like.

26. 061/BME/628Name: Rabin BasnetNickname: -Phone no: 9841641117Address: Duleguanda, TanahunEmail address: [email protected] of interest: Automobile EngineeringFinal year project: Refining of lubricating oilIOE in one word: BindasMemorable moments: Kakani picnicMy words: Higher you climb deeper you fall so, don’t look down.I’m unique coz: others might not be unique.Motto: ` Do it yourself.

27. 061/BME/629Name: Rajkumar ChaulagainNickname: RajakPhone no: 9841469752Address: Pashupati Nagar, Hetauda-9Email address: [email protected], [email protected] of interest: Mechanization, photography.Final year project: Improved Water Mill System DesignIOE in one word: Opportunity Memorable moments: Robotic events, Gorkha tour.My words: Know yourself first.I’m unique coz: I’m least ‘gaphastic’.Motto: Be punctual, struggling and optimistic.

28. 061/BME/630Name: Ramanuja DhunganaNickname: RamuPhone no: -Address: Rajahar-3, Nawal-parasiEmail address: [email protected] of interest: Automobile, hydropower and aeronautical.Final year project: Improved Water Mill System DesignIOE in one word: memorable Memorable moments: Kali-Gandaki tourMy words: Maintain positive attitude.I’m unique coz: I’ve French cut beard.Motto: Hard working is the key to success.

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29. 061/BME/631Name: Ramij Raj PandeyNickname: RajaPhone no: 9841611504Address: Kalanki, KathmanduEmail address: [email protected] of interest: MusicFinal year project: Design and fabrication of Bucket wheat dehusking machineIOE in one word: MistakeMemorable moments: Welcome party during our 2nd semester and 3rd semesterMy words: I never wish…….. I always hope for better.I’m unique coz: I’m unpredictable.Motto: The only thing that matters is time. So, always keep your eyes on the time of your life.

30. 061/BME/632Name: Ravi ShahNickname: Raw-vDate of birth: 2042/07/27 Address: Battishputali, KathmanduEmail address: [email protected] of interest: Engineering, Management, Economics, Sports Final year project: Design and fabrication of a kitchen waste based biogas plant and

testing with different feed materialsIOE in one word: CoolMemorable moments: Pokhara and Chitwan tours, ‘Photocopy’ sanga 1st time kura gardako

moment, Precious CIT moments, Nilesh risaeko din, Saathi haru ko smiles, My words: We make something good from the difficulties we face. We learn new things.I’m unique coz: I treasure relations.Motto: Live. You are here to live. Life goes on whether rain, shine, mist or fog.

31. 061/BME/633Name: Roma GurungNickname: -Phone no: 9841575327Address: Kolma Barahachaur, SyangjaEmail address: [email protected] of interest: Mathematics, Machine DesignFinal year project: Design and fabrication of Bucket wheat dehusking machineIOE in one word: Great Memorable moments: Lab classes discussions, visit to industries with friends, project work

tour, industrial attachment to Panchakanya Industry, Gorkha Tour My words: Timeliness should be maintained in the academic schedule.I’m unique coz: I’m myself.Motto: Always put faith on yourself and be cool, calm and collective.

32. 061/BME/634Name: Roshan Kumar DeoNickname: PrayashPhone no: -Address: V.D.C. Boria-7, SaptariEmail address: [email protected] of interest: so many…… (Especially aeronautics)Final year project: Design and fabrication of Institutional Metallic Cooking StoveIOE in one word: Institute Memorable moments: ManyMy words: Try to be a man of value than a man of success.I’m unique coz: I have no unique characters.Motto: Serve the society in engineering aspects.

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33. 061/BME/635Name: Rudramani GhimireNickname: -Phone no: 9841440908Address: Arjai-9, GulmiEmail address: [email protected] of interest: EnergyFinal year project: Refining of lubricating oilIOE in one word: Base Memorable moments: Energy tour to Gorkha.My words: Be always ahead than time.I’m unique coz: I’m always silent.Motto: Work on a rural development.

34. 061/BME/636Name: Salim BuxNickname: BoxerPhone no: 9841632878Address: Ward no. 2, New Road, Damauli, Vyas municipality, Tanahun.Email address: [email protected], [email protected] of interest: Aeronautical EngineeringFinal year project: Designing, fabrication and testing of Aircraft Travel Board

Certification DeviceIOE in one word: CareerMemorable moments: Call of my friend saying I was selected for

Mechanical Engineering, KaliGandaki trip, Sauraha incident and trip, Vietnam trip, India tripMy words: “Not inflicting on others that which you do not want yourself”I’m unique coz: I’m interested in every practice skilled works and no one is like me.Motto: Be prepared.

35. 061/BME/637Name: Sanjib TiwariNickname: DakuPhone no: 9841304621Address: Kuleshwor, KathmanduEmail address: [email protected] of interest: Gizmos, musicFinal year project: Study on production of briquette from pine needleIOE in one word: Wow!Memorable moments: Chitwan visit with ‘Hami group’, Kakani picnic.My words: Be cool and enjoy.I’m unique coz: I’m myself.Motto: To be a CEO of a multinational company

36. 061/BME/638Name: Santosh AcharyaNickname: Santo, KayamPhone no: 9841913884Address: Ramgram municipality-3, NawalparasiEmail address: [email protected] of interest: Automobile, music and sportsFinal year project: Performance evaluation of micro-francis turbine IOE in one word: KaiMemorable moments: All memorable moments are worth forgetting!My words: Pencil is provided with eraser on rear side to erase mistakes,

but erasing two times may tear the sheet.I’m unique coz: I’m Santosh!Motto: Yes, I’m motto!

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37. 061/BME/639Name: Shailendra BhusalNickname: BhusalPhone no: 9803592498Address: Arghakhanchi, ArghaEmail address: [email protected] of interest: Refrigeratio and A/C.Final year project: Animal driven multi-crop planter with fertilizer drillIOE in one word: RomanticMemorable moments: IOE EntranceMy words: Confident is the key to success.I’m unique coz: I have self confidenceMotto: Be optimistic.

38. 061/BME/640Name: Shankar Bogati Nickname: Bogati / HamiDate of birth: 2042/11/10Address: Kuntibandali-3, AchhamEmail address: [email protected] of interest: Travelling, Music, Hydropower Final year project: Study on the production of briquettes from pine needleIOE in one word: -Memorable moments: Sutla in heaven, Gorkha tour, Chitwan ma back,

Kulekhani tourMy words: -I’m unique coz: -Motto: Yaya hos!

39. 061/BME/641Name: Sudeep Raj SubediNickname: TankerPhone no: -Address: Chandranigahpur-1, RautahatEmail address: [email protected] of interest: Rural developmentFinal year project: Recycling of used lubricating oilIOE in one word: UtopiaMemorable moments: Dhattachment, Gorkha tour, Nagarkot picnicMy words: Be aware of JanakpuriansI’m unique coz: I am from Cha’purMotto: Prameet knows

40. 061/BME/642Name: Sujan JojijuNickname: Joju Phone no: 9841451411Address: Rani-pauwa-11, PokharaEmail address: [email protected] of interest: ManagementFinal year project: Multipurpose application, socio-economic and technical

aspect of rice husk.IOE in one word: MirageMemorable moments: Kali-Gandaki tour, all final matches of cricket, Kakani picnic My words: Do not wait others to lead you; take the lead self.I’m unique coz: I’m the master of self.Motto: Always be ready to learn.

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41. 061/BME/643Name: Sunil AdhikariNickname: DostiPhone no: 9803597307Address: Damauli, TanahunEmail address: [email protected] of interest: AutomobilesFinal year project: Improved Water WheelIOE in one word: GoodMemorable moments: Gorkha tourMy words: Be active.I’m unique coz: I am Dosti (Dashing, Outstanding, Smart, Talented, Intelligent) Motto: Be a successful person.

42. 061/BME/644Name: Suraj Dahal Nickname: RajabadiPhone no: -Address: Gothatar, Kathmandu Email address: [email protected] of interest: Arms and AmmunitionsFinal year project: Multipurpose application, socio-economic and technical aspect

of rice husk.IOE in one word: UnforgettableMemorable moments: Playing cards in class in 2nd year, picnics, Welcome and farewellMy words: Unity and DamiI’m unique coz: I am Jungali.Motto: To serve my mother and motherland

43. 061/BME/645Name: Surendra MaharjanNickname: Mana/SuriPhone no: 01-4212997Address: Bhurngkhel, KathmanduEmail address: [email protected] of interest: AutomobileFinal year project: Solar cum Hybrid Tunnel DryerIOE in one word: ‘Ramilo Mela’ Memorable moments: Result day of 3rd year 1st part.My words: Live and let live (No interference in privacy)I’m unique coz: there is no other like me.Motto: Hello motto!

44. 061/BME/646Name: Tarzan NakarmiNickname: Taru BhaiPhone no: 9841122504Address: Namuna Bast-8, JanakpurEmail address: [email protected] of interest: Music, Cricket, DesignFinal year project: Design and fabrication of sticker labeling machineIOE in one word: Not badMemorable moments: Return trip from ‘Lakure Bhanjyang’My words: Always plan in advance as how to stay at the top before

attempting to go there coz reaching top is not a difficult task but staying there is. It is just like sleeping on bed of thorns.

I’m unique coz: I don’t think I’m unique as others do.Motto: Pramit knows i.e. “Don’t ever provoke anyone’s ego and …………….”

45. 061/BME/647Name: Ujuma Shrestha

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Nickname: UzuPhone no: 9841408214Address: BhaktapurEmail address: [email protected] of interest: Management and mediaFinal year project: Design and fabrication of moon buggyIOE in one word: FunMemorable moments: Don’t have so many of them.My words: Live to express yourself, not to impress someone else.I’m unique coz: My name is Uzma.Motto: Live your life to the fullest.

46. 061/BME/648Name: Anil MaharjanNickname: -Phone no: 9741083083Address: Lagan-21, KathmanduEmail address: [email protected] of interest: DesignFinal year project: Performance evaluation of modular type hybrid solar dryerIOE in one word: GreatMemorable moments: Picnic (Kakani)My words: All the moments of 4 years in IOE will always remain fresh in my

memories and hope all friends will meet at some point of life.I’m unique coz: I believe I’m unique.Motto: Wanna reach the top? Always start from the base.

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061 batch students after felicitation in Chepang basti, Gorkha at Renewable Energy Tour

061 batch students in Nagarkot Picnic, 2065 Poush