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First of all, I need to thank almighty God for the great protecting of me in health and helping me

to do everything on time.

Great thanks to my advisors Dr. Alemayehu Kiflu. and Ato Ashenafi Hailu. for the progressive

advising, providing materials, and equipments and supporting me in all my work that make me to

complete the thesis successfully.

Great thanks to Ethiopian petroleum enterprise (EPE) for helping me with quick experiment

result with no killing of my time specially centre head of petroleum quality testing, Ato Manaye

Balcha.

I wish to thank all my classmates that the cooperative advising of one another, working things

together.

Lastly, thanks to chemical department of Bahir Dar University, for the enough computers

providing to get internet service and writing on it and allowing to me lab to my experimental test.


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Contents pages

ACKNOWLEDGEMENT ............................................................................................................. i

TABLE OF CONTENTS .............................................................................................................iiIndex of Tables ..........................................................................................................................v

Index of Figures .......................................................................................................................v

Nomenclatures ........................................................................................................................ v

viii

1.1 Problem Statement .....................................................................................................5

1.2 Objectives of the study ................................................................................................6

1.2.1 General objective ....................................................................................................... 6

1.2.2 Specific objectives...................................................................................................... 6

1.3 Methodology ...............................................................................................................7

1.4 Background .................................................................................................................8

1.4.1 Ethanol stove development .................................................................................... 8

1.4.2 Impacts of Household Energy Patterns ................................................................ 11

1.4.3 Clean cooking fuel, ethanol and benefits............................................................. 15

2.1 Property of ethanol ...................................................................................................19

2.2 Ethanol- water mixture .............................................................................................21

2.3 Determination of ethanolwater mixture property ..................................................23

2.3.1 Boiling point pressure and temperature ............................................................... 23

2.3.2 Fraction distillation of an azeotrope of ethanol-water mixture ............................... 25

2.3.3 Enthalpy of mixing .............................................................................................. 262.4 Partial molar volume .................................................................................................29

2.5 The maximum flame temperature ............................................................................30

2.6 Flammablity of ethanol-water mixture fuel ..............................................................34


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2.7 Activity coefficient of ethanol-water mixture fuel ...................................................36

2.8 Flash-point of ethanol- water mixture analytical estimation ..................................38

3.1 Potential and quality of ethanol production in Ethiopia .........................................40

3.2 Ethiopia Policy toward using of ethanol as cooking fuel .......................................41

3.3 Optimal flammable ethanol-water mixture ..............................................................42

3.3.1 Flame height measurement set-up...................................................................... 42

3.3.2 Flash-point measurement set-up ........................................................................ 44

3.3.3 Data analyzing .................................................................................................... 45

3.3.4 Experimental Result and discussion ................................................................... 46

4.1 The stove Parts specifications .................................................................................50

4.2 Burner holes diameter ..............................................................................................53

4.3 Vertical height of flame .............................................................................................57

4.4 Heat losses through stove .......................................................................................58

4.4.1 Radiation from flame ........................................................................................... 58

4.4.2 Convection from flame ......................................................................................... 694.5 Air-to- fuel ratio .........................................................................................................61

5.1 Efficiency of the stove ..................................................................................................63

5.2 Material and Cost estimation .......................................................................................65

5.3 Parts and Manufacturing Process ...............................................................................67

5.4 Operation and Working Principle of the Stove ...........................................................68

6.1 Conclusion ....................................................................................................................69

6.2 Recommendation.........................................................................................................70


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Index of Tables

Table 2-1: Physical property of ethanol and water ........................................................... 24

Table 2-2: Antoine constants of ethanol and water ........................................................... 25

Table 2-3: Maximum flame temperature and % volume of ethanol ................................... 35

Table 3-1: Ethanol production capacity of Ethiopia (1000 liters) ....................................... 40

Table 3-2: The measured mean flame height of ethanol-water mixture ............................ 46

Table 3-3: Property summary of 60 % ethanol-water mixture ............................................ 49

Table 4-1: Thermal property of liquid hydrocarbon fuels .................................................. 55

Table 5-1: Cost and specification of materials of stove .................................................... 65


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Index of Figures

Figure 1-1: Two burner CleanCook ethanol stove.............................................................. 9

Figure 1-2: Low concentration ethanol stove ................................................................... 10

Figure 1-3: Ethanol stove for both cooking and lighting ..................................................... 11

Figure 1-4: Rural house wife from fire wood collection ...................................................... 14

Figure 2-1: Ideal case partial pressure of ethanol, water and ethanol-water mixture ......... 24

Figure 2-2: Mixing enthalpy of ethanol-water mixture ....................................................... 28

Figure 2-3: The calculated volume change OF 10 mL sample........................................... 30

Figure 2-4: Combustion model of controlled system .......................................................... 31

Figure 2-5: Activity coefficient of ethanol-water mixture by UNIFAC ................................. 38

Figure 3-1: Flame height measure set-up ........................................................................ 44

Figure 3-2: Flash-point measure set-up ............................................................................45

Figure 3-3: Flash-point and ambient temperature relation ................................................ 47

Figure 3-4: Flash-point data of ethanol-water mixture ...................................................... 48

Figure 4-1: Parts of the stove ........................................................................................... 51

Figure 4-2: Top surface area of canister or burner ........................................................... 53

Figure 4-3: Librated heat energy and single burner hole burner ....................................... 56

Figure 4-4: Vertical height of hottest zone flame .............................................................. 57


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a Activity

AFR Air-to-fuel ratio

Cl Confidence level

Specific heat capacity at constant pressure Burner hole diameterFFV Flex-fuel vehicles

LFL Lower flammability limit

Flame heightLPG Liquid petroleum gas fuel

P Pressure

Q Heat energy

T Temperature

UFL Upper flammability limit

x Mole fraction of ethanol in water mixture at liquid state

y Mole fraction of ethanol in water mixture at vapor state

Absorpibity Radiation Boltzmann constant (5.67X10-8 w/k4m2) Emissivity of flame Activity coefficient


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Ethiopia is the third largest user of traditional cooking fuels and this leading to environmental,

ecological, economic, and healthy impacts. To improve the quality of life and to avoid these

negative effects, clean and renewable alternatives fuels are selective for cooking.

The availability of clean cooking and lighting fuels which are renewable and can be produce

locally will be the first and an important step in raising the quality of life in the case of cooking.

Liquid or gaseous fuels are far superior to solid fuels for cooking because of their clean

combustion and existing supply chain convenience and high energy content. Again, liquid fuels

are most suitable since they have much higher energy density than gaseous fuel like biogas or

LPG and easy handling.

Among all the liquid fuels that can be produced locally and in a renewable manner, ethanol is

one and the best alternative. Thus, it is an excellent substitute for kerosene and burns better than

kerosene without any particulate output or unpleasant smell of combustion and its renewability.

Ethanol used for cooking in most areas with different concentration of water in order to reduce

its flammability hazard. Therefore, the optimal flammable ethanol-water mixture is between

inflammable water and flammability hazard of ethanol.

This study is going to come-up with the optimal flammable clean cooking ethanol-water mixture

stove for house hold cooking purpose of Ethiopia in both experimental and analytical

investigation. Maximum temperature of flame of mixture is calculated using combustion energy

balance and vertical flame height and flash-point is measured. In both determinations, 60% (v/v)

ethanol-water mixture is selected as the optimal flammable solution for the household cooking. It

get as flash-point 23.7oC and vertical flame height is 5.41 Cm. Increasing the flash-point of

ethanol is to make it safe for house hold cooking purpose.

Key words: Clean fuels, Ethanol, Flammability hazard, ethanol-water mixture


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Food to be cooked to make it favorable and the right absorption of our body, heat energy used tocook beside with killing or inactivating the potential of harmful organisms including bacteria or

virus and to change the flavor of food with food ingredients. There are many methods of

cooking, and among which have been known are; baking, roasting, frying, grilling, barbecuing,

boiling, steaming, and braising. All methods of cooking needs heat energy and that may get from

burning of firewood, biofuels, LPG and other fossil fuels as energy source. Cooking is an activity

unique to humans and some scientists believe that the advent of it played an important role in

human evolution and development. Most anthropologists believe historically that cooking fires

first developed around 250,000 years ago before starting of cook. The development of

agriculture, commerce and transportation between civilizations in different regions offers the

development of cooking with many different new ingredients. New inventions and technologies

such as pottery for holding and boiling water, improved cooking techniques with the life change

revolution develop through time. Some modern cooking stoves apply advanced scientific

techniques to food preparation and saving of energy in safer manner within a little cooking time.

Therefore, the system of cooking, cooking stove, and cooking fuel is still in developing through

time to time with advance of the life standards. Therefore, the progress development of cooking

stoves is mainly based on saving of energy, with no or little smoking, stove functionality in

different cooking fuels, and cooking time and like. To achieve all these goals, design and

development of different cooking stove accordingly its available fuel still not satisfied.

Using of traditional fuels for cooking has negative effects on environmental, economic and

healthy impacts. That is, the ample use of firewood and charcoal leads to deforestation, leading

to ecological imbalance, and increased use of agricultural residues and animal dung deprives the

land of essential nutrients that are necessary for soil fertility. Similarly, uncontrolled use of

traditional cooking fuels is destruction of ample of cooking fuels and wastage of time.


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Furthermore, smoke from the use of fuel wood, animal dung, and agricultural residue for

cooking contributes to acute respiratory infections. This latter problem, i.e., indoor air pollution

is worse in poor countries where households houses are not equipped with separate living with

cooking places and selected air conditioning system.

Therefore, for the development of clean cooking fuel these steps are followed:

Changing cooking habits is not an easy task; users have to be convinced that there are

better methods than the traditional way.

Improved stoves and clean stoves have to be efficient, clean-burning and convenient;

they have to look modern and must still be affordable.

Experiences of many different household energy initiatives have shown that a

commercial approach is the most successful and sustainable way of promoting improvedcooking technologies.

Finally the availability of both fuel and stove to be prepared for the individual household

users.

Ethiopia is the third largest user in the world of traditional fuels for household energy use; this is

in comparison to 90 % of Sub-Saharan Africa and approximately 60 % of the African continent

[1]. As reported by the Ethiopian Rural Energy Development and Promotion Center (EREDPC

1998), in 1996, the most recent year statistics on the energy sector shows, 77 % of total finalenergy consumption consisted of firewood and charcoal while another 15.5 % consisted of

agricultural residues, and only roughly 7 % was met by modern energy sources such as

petroleum and electricity.

Accordingly EREDPCA report, over 90 % of Ethiopia population using fire wood, agricultural

residues, charcoal and animal dung but all such fuels produce high emissions of carbon

monoxide, hydrocarbons and particulate matter during cooking. Hydrocarbon emissions are

highest from the burning of dung for fuel, while particulate emissions are highest from

agricultural residues. Women and children suffer most from indoor air pollution because they are

traditionally and culturally responsible for cooking and other household activities that involve

spending hours near the cooking fire and exposed to smoke. Young children are particularly


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susceptible to disease, which accounts for their predominance in the statistics for premature

deaths due to the use of biomass for cooking.

The effects of exposure to indoor air pollution depend on type of fuel and stove efficiency, how

pollution is dispersed and how much of their time household members spend in indoors. Thetype of fuel used and individuals participation in food preparation have consistently been the

most important indicators of indoor pollution. As well as being much more dependent on

biomass, poor households rely on low-quality cooking equipment and live in poorly ventilated

housing, exacerbating the negative health impact, as there is incomplete combustion and non-

dissipation of smoke in the area. The overall impacts in using traditional biofuel in cooking

process are in detail found in section 1.4.2.

Ethiopian demand for clean cook energy sources is expected to grow faster than for any other

energy source; biomass fuels will continue to dominate total energy consumption and the effects

for which is to live without any harmful consequences. The energy and environment policies of

Ethiopia supports the initiatives and introduction of clean cook fuels, the drafts of biofuel

strategy is also prepared. This is the critical measure for the improvement of economy and

healthy of residents.

The availability of clean cooking and lighting fuels, which are renewable and can be grown

locally, will be the first and an important step in raising the quality of life of rural population. No

modern society uses solid fuel like coal or wood for cooking. Liquid or gaseous fuels are far

superior to solid fuels for cooking because of their clean combustion and existing supply chain

convenience and high energy content. Again, liquid fuels most suitable since they have much

higher energy density than gaseous fuel like biogas or LPG and easy handling.

Among all the liquid fuels, which can be produced locally and in a renewable manner, ethanol is

one and the best. Thus, it is an excellent substitute for kerosene and burns better than kerosene

without any particulate output or unpleasant smell of combustion and its renewability. Hence, the

use of ethanol fuel for cooking and lighting for rural areas should be encouraged to sustain all

environmental, economic, and healthy impacts of cooking.


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This study is going to develop clean cooking ethanol stove for household in optimum flammable

in water mixture for cooking. After testing of different ethanol-water percentage of mixture in

flammability and having of enough energy for cooking, the best solution is selected and

therefore, the stove designed for the selected concentration of ethanol-water mixture.


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1.1 Problem Statement

In Ethiopia, together with under developed areas of Africa, the use of traditional fuels and fossil

fuels for cooking is facing housewife and cooking bodies in different diseases due to poor indoor

air quality and deforestation problem of the area which further leads to ecological imbalance.

Using of fossil fuels for cooking in urban area leads to energy crises and assisting of global

warming problem. Ample using of wood for cooking and charcoal production makes most area

desert and destroyed forests and forest habitants. Identification of this problem from different

area is leading to think idea toward to use clean and renewable fuels for cooking.

Among the clean and renewable fuels, liquid fuels are superior in their high energy density and

easy handling. Ethanol is a good alternative except its pure case flammability hazard. For

different design models of the stove, cooking energy of flammability of ethanol with water

solution, but optimal percentage is still not determined. For the economy of the fuel and

sufficient energy content, the best percentage of ethanol-water mixture for cooking is not known

quantitatively. Thus, the use of ethanol for cooking is not in progress.

The production of ethanol in Ethiopia is not using in our country, it export but the other cooking

fuels import from other country and others consumes electricity. The current production and

future development of ethanol production is not motivated if the ethanol market not encouraged

linearly with the production rate.

If the ethanol stove is designed, and manufactured, and distributed in our country, both the

economic and indoor air quality problems, deforestation and ecological imbalance value

confidently to be improved and the same time agricultural based country agro-business

encouraged.


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1.3 Methodology

The methodologies incorporated to achieve the specified objectives of the study are the

followings:

Data collected for the quality of ethanol production in major sugar factories of

Ethiopia.

Reviewing of books, internet sites, journals, and magazines that can be source of the

study and increases the idea of research.

Experimental carried in different percentage of ethanol-water mixture; and the values

of flame height and flash-point measured, and observation of flame property.

Based on the experimental flame data flame height, flash-point comparison, analytical

calculation of energy, and flame property observation the best flammable ethanol-

water mixture to be selected.

For the selected best concentration of ethanol-water mixture stove designed; the fuel

storage, and burner combustion area, and flame turbulence area of combustion to be

sized.

Assembled and detail drawing of the stove for detailed description of the stove of thedesign to be included.

Economic evaluation and comparison with other stoves to be conducted.


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1.4 Background

1.4.1 Ethanol stove development

Now a day, number of design and models of ethanol stoves are designed and in use most area of

the world. Since, ethanol having of high flammability, pure ethanol cant use in domestic

purpose. Ethanol is clean and non toxic fuel that can use in wide range of applications, either as

additives of automotives fuel, and domestic cooking purpose. The only hazard associated with

ethanol is its high flammability in pure form. It has wide range of flammability, the upper

flammability limit (UFL) 19 % and lower flammability limit (LFL) 3.3 % in volume ratio to air

content [2]. When the content of water increases in a solution of ethanol and water mixture, the

combustion stochiometric air requirement is increase and hence the flammability to be reduced.

Thus, mixing it with water is one alternative technique to use ethanol for cooking by reducing its

hazardous flammability.

One of the ethanol stove designed before is, CleanCook of Gia project ethanol stove, which is

designed and manufactured in Swedish company as shown figure 1-1. It works in the

concentration of 95 % ethanol, and 4.5 % water less of 0.5 % of other additives in volume ratio

[3]. It introduced to Ethiopia during the protracted conflict of Somalia, for disrupted people of

refunge camp. The CleanCook stove is modeled on the Origo stove, which was invented in

1979 by Bengt Ebbeson and developed for the European and North American leisure market. Itsmodel has both single and double burner. The CleanCook is currently manufactured in

Slovakia, but the possibility of local production by Makobu Enterprises PLC of Ethiopia is

underway. This local production is in its early stages in Addis Ababa, with a starting goal of

18,000 stoves to be produced yearly.


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Figure 1-1:Two burners CleanCook ethanol stove (95 % v/v ethanol-water mixture) [3]

Gaia Association collected indoor air pollution data under CEIHD (Center for Entrepreneurship

in International Healthy and Development) guidance homes in Addis Ababa and refugee camps

through Ethiopia. Gaia Association is an Ethiopian NGO formed to further the aims of Project

Gaia research studies, which has as its purpose to demonstrate the use of alcohol fuels for

household and refugee use in Ethiopia. The association seeks to replace existing traditional fuels

such as firewood, kerosene, charcoal, and dung that have been shown to be harmful to human

health.

A study was conducted in a total of 9 households in Addis Ababa and consisted of indoor air

quality monitoring for 48 hours both before and after the introduction of the CleanCook stove.

Monitoring equipment was again positioned in kitchens in accordance with the standard

placement protocols given by CEIHD. They also stated as using of two extra additives for the

change need of colorless ethanol-water mixture to colorful and bittering to avoid the inhalation

problem of peoples during cooking.

The average particulate matter concentration in the kitchens was reduced after the households

began using the CleanCook stove (from 640 g/m3 to 230 g /m3), a very significant

improvement in indoor air quality. The households moved closer to the WHO interim target (75

g/m3) for PM2.5 and the Air Quality Guideline (25 g/m3) in the after phase. The average CO


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kitchen concentration in charcoal and kerosene stove case was 28.5 mg/m3 and dropped to 6.7

mg/m3 with the CleanCook stove, below the WHO guideline of 10 mg/m3 (Annex A) [4].

The other model of ethanol stove designed, manufactured, and distributed to consumers is low-

concentration ethanol stove in rural areas of India, as shown in figure 1-2. It works in weight

ratio of 50 % ethanol-water concentration and uses hand pump to pressurize the fuel from the

separate fuel tank to the burner canister [5].It is an ethanol stove running on 50 % ethanol-water

mixture has been developed at Nimbkar Agricultural Research Institute (NARI) the first time

makes and the idea of its development is very novel. Field tests conducted on the stove show that

it is safe to use and very suitable for a typical rural household and average CO concentration near

the stove is found as 9 ppm. In addition, the cost of using the ethanol stove is comparable to

those of the conventional liquid fuel alternatives. It is the lowest ethanol in water content andthus it called as low-concentration ethanol stove. Nimbkar Agricultural Research Institute

(NARI) was the first to propose and develop a stove running on 50 % ethanol-water mixture to

solve the cooking fuel crisis. This mixture is selected for which it can easily be distilled very

efficiently in a rudimentary rural distillation unit. It burns very cleanly without any smoke or

smell and has clear yellowish than blue of pure ethanol.

Figure 1-2:Low concentration ethanol stove (50 % w/w ethanol-water mixture) [5]

Nimbkar Agricultural Research Institute (NARI) also developed Ethanol stove for both cooking

and lighting area where having deficiency of alternative lighting source. The clear white


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yellowish color flame used in cooking gives light for the area near stove present as shown figure

1-3 below. It is usually a low grade between 45-60 % (w/w) ethanol-water concentrations [6].

Figure 1-3: Ethanol stove for both cooking and lighting (45-60 % w/w ethanol-water mixture)

[6]

Many small projects also conducted by the base of ethanol flammability for cooking, lighting

and other applications. Different models are also available in internet, YouTube video of ethanol

fire rating and applications.

The main attention of this study to come-up with best concentration of ethanol-water mixture

based on safe flammability for household cooking purpose. Finding of safe flammable ethanol-

water concentration is the most economical in comparison of fuel consumption and stove design

consideration in feasibility. Ethanol and water molecular similarity and due to weak hydrogen

bond makes them complete miscible. Using of pure ethanol for household cooking is dangerous

due to its high flammability of alcoholic property. So, the optimal value of ethanol-water mixture

for cooking is between the inflammability of water and high flammability of ethanol.

1.4.2 Impacts of Household Energy Patterns

Naturally, dry air is a mixture of 78 % nitrogen, 21 % oxygen, 0.03 % carbon dioxide as well as

argon and other trace concentrations. Air is said to be polluted when one or more of


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contaminants present in sufficient amount for such duration as to affect the physical well being

of people, animal, vegetation, or materials.

Traditional biomass such as fuelwood, agricultural waste and animal dung, to meet the people

daily energy needs of cooking used in most areas of the world. This accounts over 3 billionpeoples in the world, and 575 million people (76 %) in sub-Sahara Africa. Since Ethiopia is the

third largest user in the world of traditional fuels for household energy use, which is accounted

over 90 % dependency of traditional biomass for cooking [7].

Even if traditional fuels were harvested sustainably, it would not be carbon neutral due to its

incomplete combustion in the idealized fuel cycle in which all the carbon is converted to carbon

dioxide and is not a realistic model. Due to its incomplete combustion, carbon is released in other

forms and including methane (CH4), nitrous oxide (N2O), carbon monoxide (CO) and non-

methane hydrocarbons and sulfur compound. These compounds are referred to as products of

incomplete combustion and have a much greater potential impact on climate change. Therefore,

the category of fuel in cooking which can produce little or no such impure compounds we called

clean cook fuels and their importance and advantage is shown in detail in the next section.

Cooking with wood fires is also unsustainable and contributes to rapid deforestation in the

developing world. Where wood is already limited and taking of long time to replacement, its

collection leads to desertification. In Africa, collection of wood for cooking and charcoal

production is the primary reason for the disappearance of the forests. Further, the burning of

hydrocarbon fuels, coal, charcoal, and even dung contributes to the accumulation of greenhouse

gases. Smoky cooking fires and stoves contribute to the soot that is estimated to cause

approximately 16 % of global warming. Black carbon particles in the atmosphere are considered

one of the most dangerous pollutants after carbon dioxide. The World Health Organization

estimates that 1.5 million premature deaths per year are directly attributable to indoor air

pollution from the use of solid fuels. That is more than 4,000 deaths per day, more than half ofthem children under five years of age. This means that indoor air pollution associated with

biomass use is directly responsible for more deaths than malaria, almost as many as tuberculosis

and almost half as many as HIV/AIDS.


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In Ethiopia, about 200 hectare forest cover is lost annually because of people need to cut trees for

firewood. With that about two billion square meters of soil is lost annually due to erosion

consequently farm yield potential is reduced by 2 % every year [8]. This is fatal for such a poor

under poverty level agriculture based country that is still not able to cover its own daily hand to

mouth food demand. In addition, beside environmental and agricultural consequences, the energy

of household has further economical and healthy impacts. Though fossil fuels account only for

5% of the primary energy consume in Ethiopia, they costs nearly 50 % of the export earnings of

this developing country. Moreover, the world market prices are rising with the economic and

progress with standard of life for the future expectation is make more fear.

Beginning with health, it estimated indoor air pollution of cooking results in 1.6 million deaths

worldwide each year, and among 24 % of which occur in Africa. Therefore, the primary cause of

this indoor air pollution is household fuel use, particularly from traditional fuels burned in highly

inefficient traditional stoves. Since, Ethiopia is in position as the third largest user in the worlds

of traditional fuel with the habit of burning fuel wood in the traditional three stone fire place

whose efficiency is just 5 to 10 % compared to 70 to 80 % of an electric stove.

It is clear that, in Ethiopia most population resides in rural area where only wood and agricultural

residue to be used for cooking, using traditional mud cooking pots, and inefficient open cooking

condition needs lots of energy. Thus, for the need of high cooking energy and long cooking time

need results the high emission particulate concentration and these influences the life of cooking

mothers frequently.

In the way of energy use patterns affect different members of the household to varying degrees

are not limited to health. The major task division acquiring sufficient energy in Ethiopia to meet

in family basic needs of food and shelter culturally delegated to the women of the household than

men depending on access to energy and biomass. Rural housewife and children of Ethiopia travel

up to 12 kilometers from their home to collect cooking fuels. They are also force to collectinferior fuels in the form of bushes, twigs, roots, and crop residues and all of which translate into

longer preparation and cooking times; the same is true for urban women, who also operate under

extremely harsh conditions and, like their rural counterparts, have to walk long distances on


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harsh terrain, often barefoot, and with heavy loads. Border guards at checkpoints will sometimes

harass these women, demanding bribe money to allow them to bring in fuel. Traditional healers

in the urban centers of Addis Ababa and Delanta often treat women for severe abdominal pains

attributed to carrying these heavy loads over long distances. Once collected, additional time must

be spent by women preparing the fuels for use not only in cooking, but also in the supply of

water, space heating, and for use in household processing industries, often crucial as income and

employment generating sources.

Figure 1-4: Rural housewife from fire wood collection

These impacts are not felt equally all members of the household. The WHO (2004) estimates that

just over half of worldwide deaths in children under the age of five are caused by indoor air

pollution, while the proportion of the total global burden of disease in children of the same age

caused by indoor air pollution is a staggering 80 %. In regards to Ethiopia, those same reasons

offered above as to why Ethiopians likely share in the count of worldwide deaths from indoor air

pollution similarly apply here. Furthermore, as the majority of household energy demand in

Ethiopia is due to cooking, with approximately 50 % of Ethiopias primary energy consumption

used to bake injera, women also share an unequal burden of death and disease from indoor air

pollution as they are the primary cook; studies have shown that emissions are not equally

dispersed about a room, but rather are highest at the source of combustion, decreasing as

movement away from the energy source occurs.


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1.4.3 Clean cooking fuel, ethanol and benefits

A sustainable energy production and consumption is a basic need for under developed countries

for sustainable development and energy access for daily the basic needs. It is a very important

precondition for education, health, economic progress as well as for a reliable food supply.

Energy is also strongly related to the local, national and global environment. The lossing of

forests, farm lands, and wild life by desertification and whole eco-systems imbalance and also

the dramatic impacts of climate change are all consequences of non-sustainable traditional

energy generation and consumption.

Some of the clean and renewable fuels for cooking are gaseous fuels like biogas, solid fuels like

charcoal, and liquid fuels like biodiesel and ethanol. However, due to their high energy density,

easy transportability and storage the liquid fuels are superior to other renewable alternatives. The

selection and demand of household energy is mainly depends on not to harm cooking mothers,

availability in that area, and suitable to handle.

Liquid fuels are considered to be a good alternative in easy handling rather than solid and

gaseous fuels for house hold purposes. Among all the liquid fuels which can be produced locally

and in a renewable manner, ethanol is one of the best biofuel. It is an excellent substitute for

kerosene and burns better than kerosene without any particulate or unpleasant smell and its

renewability and local production make ethanol better. In fact, its combustion is almost as cleanas that of LPG. Hence, the use of ethanol fuel for cooking and lighting for rural areas needs to be

encouraged for developing rural areas. Combustion of a liquid fuel in an oxidizing atmosphere

actually happens in the gas phase. Therefore, a liquid will normally catch fire only above a

certain temperature: its flash point. The flash point of a liquid fuel is the lowest temperature at

which it can form an ignitable vapor composition for easy mixing with air.

Several countries in Africa are currently distilling ethanol at significant scales, including

Ethiopia, Kenya, Malawi and Zimbabwe. The ethanol produced is mainly used as an additive intransportation fuels. Ethanol is produced by fermenting the sugars containing various types of

biomass feedstock. It can also be produced from starches if they are first converted into simpler

sugars. The resulting mixture is then distilled to yield a high concentration or pure ethanol in


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minimizing of water content of fermentation solution. There are a wide range of crops that can

be used as feedstock or inputs of ethanol production, including sugarcane, cassava, sweet

sorghum, maize and wheat. The ideal feedstock for the production of ethanol is dependent on

regional climate and soil conditions, the crops annual cycles, and available technology.

Alcohol fermentation is done by yeast and some kinds of bacteria. These microorganisms

convert sugars in to ethyl alcohol and carbon dioxide. Alcoholic fermentation begins after

glucose enters the cell. The glucose is broken down into pyruvic acid. This pyruvic acid is then

converted to CO2, ethanol, and energy for the cell. The yeast secretes enzymes that digest the

sugar (C6H12O6), yielding several products including lactic acid, hydrogen, carbon

dioxide (CO2), and ethanol (C2H5OH) with water contents. Thus water content is further

separated from ethanol by continuous distillation and carbon dioxide to be push out through

chimney.

The chemical equation of the dissociation summarized in equation 1-1, the fermentation

of glucose, whose chemical formula is C6H12O6. One mole of glucose is converted into two

moles of ethanol and two moles of carbon dioxide:

C6H12O6 2C2H5OH + 2CO2 (1-1)

While ethanol is still in development as a cooking fuel in many African countries, Project Gaiahas taken the lead in Ethiopia to make it commercially available to urban households. A large

number of stakeholders have contributed to the effort. With respect to ethanol production,

Ethiopias position among other sub-Saharan African nations is unique: since 2008 eight million

liters of ethanol are produced from waste product molasses at the Fincha Sugar Factory each

year, and none of this ethanol currently has a market. Because of this great potential, Domestic

AB introduced the ethanol-compatible CleanCook Stove and conducted a pilot study among

850 Addis Ababa households and emission rate is estimated. The study confirmed the stoves

popularity among users, who cited a number of benefits.


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Therefore, ethanol is the most favorable clean cooking fuel among other clean cooking fuels.

That is based on its easily handling and transportation, low emission rate and having of capacity

to produce. This is the idea for this study to select ethanol for cooking and develop ethanol stove.

Reduced deforestation

The loss of the worlds forests is a pressing environmental issue: the global forest area is

decreasing by 0.2 % per year. The rate of deforestation is greatest in Africa, where the area of

forested land decreases by about 0.6 % per year. In case of Ethiopia over 200 hectare cover

forest is losing annually due to using of traditional cooking with traditional fuels [9]. Researchers

have pointed to numerous causes for this high rate of loss, including agricultural expansion,

firewood collection, charcoal production, timber harvesting, and development of infrastructure.

Despite the difficulties inherent in measuring the extent to which these factors contribute todeforestation, a number of studies have attempted to do so. The findings of these studies vary

depending on their regional focus. Despite regional differences there is a clear link between

wood fuel extraction and deforestation: a statistical analysis that includes data from 40 African

nations reports a strong correlation between the rate of deforestation and the rate of wood fuel

production. A transition to clean cooking fuels has the potential to reduce the rate of sub-Saharan

deforestation as households would depend less on wood fuel for energy.

Climate change mitigation

The predominance of wood fuel in household cooking is related to global climate change through

two primary mechanisms. First, to the extent that biomass for wood fuel is being harvested at an

unsustainable rate (i.e. the rate of extraction exceeds the rate of replenishment since it takes long

time for replacement) the capacity of the biosphere to remove carbon dioxide from the

atmosphere is reduced. Secondly, because of the combustion of wood fuel in household cooking

is incomplete as I have stated before, some of the carbon in the wood fuel is released in forms

other than carbon dioxide, which may have a greater effect on surround climate. Because of

deforestation, the amount of carbon that can be stored in the biosphere is continually decreasing,

which results in a net increase of carbon dioxide in the atmosphere since reduction of carbon

dioxide absorbing plantation. In the most ideal biomass fuel cycle, one in which combustion is


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completed so that all the carbon is converted to carbon dioxide. When the sustainability

condition is not met, the rate at which carbon dioxide is emitted exceeds the ability of the forests

to remove it from the atmosphere, resulting in increased atmospheric concentrations of carbon

dioxide and similarly other pollutants.

Reduction of indoor air pollution

The wood fuel, agricultural residue, and animal dung that most of Africas households use for

cooking are major sources of indoor air pollution. The inefficient and incomplete combustion of

these fuels release a number of hazardous pollutants, including carbon monoxide, sulfur and

nitrogen oxides and particulate matter and soot accumulation. In many households, poor

ventilation exacerbates the effects of these pollutants and women children are often exposed to

them at significant levels for between three, and seven hours each day accordingly cooking time.

Such prolonged exposure to indoor air pollution has been implicated in the increased incidence

of a number of respiratory, and eye diseases in developing nations. Therefore, in using of clean

cooking fuel completely avoids indoor air pollution.

Safety issues for clean liquid and gaseous fuels for cooking in the scope of

sustainable development

Several fuel types have been used for cooking throughout the world, ranging from solid fuels to

liquid to gas. Gaseous fuels are considered cleaner because of their inherent characteristics of

low pollutant formation and emissions during handling and during cooking. Nevertheless, from

the viewpoint of sustainable development, other safety properties are important to know, such as

flammability limits, autoignition temperature, specific gravity, vapour pressure, toxicity and

flash point. The value of these properties of ethanol-water mixture is tabulated in appendix at end

page of the paper.


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2.1 Property of Ethanol

Ethanol under ordinary condition is a volatile, flammable, clear, colorless liquid. Its odour is

pleasant, familiar, and characteristic, as is its taste when it is suitably dilute with water. Ethanols

miscibility with water contrasts with that of longer-chain alcohols (five or more carbon atoms),

whose water miscibility decreases sharply as the number of carbons increases. The physical and

chemical properties of ethanol are primarily dependent upon the hydroxyl group. This group

imparts polarity to the molecule and also gives rise to intermolecular hydrogen bonding. In the

liquid state, hydrogen bonds are formed by the attraction of the hydroxyl hydrogen of one

molecule and the hydroxyl oxygen of a second molecule. It is completely miscible with water

and organic solvents and due to its high hydroscopic readily absorbs water from air and this is

due to having of weak hydrogen bonding. Ethanol has widespread use as a solvent of substances

intended for human contact or consumption, including scents, flavorings, colorings, and

medicines. In chemistry, it is both an essential solvent and a feedstock for the synthesis of other

products. It has a long history as a fuel for heat Combustion. Ethanol has a boiling point 78.5 oC

and specific density of 0.793 at 20 oC.

Complete combustion of ethanol forms carbon dioxide and water in pure case at STP:

C2H5OH + 3 O2 2 CO2 + 3H2O (l) (2-1)

Flash point is a unique property of a liquid fuel is to know the relative hazard of fuels and used to

classify the liquid fuels whether flammable or combustible. Flash point is a lowest possible

temperature at which a fuel has enough flammable vapourto ignite by the surrounding air. For

pure ethanol flash point is 13.4 oC and the highest flash-point is at a mixture of 5 % v/v ethanol-

water mixture and which is 62 oC thus the safety of ethanol for household application in open air

is increase with increase of water content. Any liquid with a flashpoint less than 37.8 C is

considered as flammable liquid. Any liquid with a flashpoint between 37.8 C 92 C is


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considered to be combustible liquid [10]. Therefore, ethanol-water solution is considered as

flammable for the ethanol percentage greater than 20 and less than of it is classified as

combustible liquid (Annex B).

Comparing the flammability limit for the fire hazard maintenance of ethanol with othershydrocarbon fuels like kerosene, gasoline and diesel, ethanol has the highest value of lower

flammability limit (LFL). Accidental fires often occur because flammable vapor increases from a

fuel at low level flammability producing the minimum concentration of ignitable vapour at

which ignition will occur. The higher the value for the LFL, the less likely a fire hazard will

result. Thus, a high value for LFL is considered to be safer than a low LFL value. Ethanol has a

LFL value of 3.3 % in air at room temperature and methanol a value of 6.0 %. These values are

significantly greater than for kerosene at 1.7 % and gasoline at 1.4 %. Depending upon the nature

or composition of the kerosene, its LFL can sometimes be lower up to 0.7 %. The LFL of diesel

is 0.6 % [11].

Ethanol is the most flammable alcoholic fuel. A method for maintaining a flammable solvent is a

treating with a nonflammable environment involves maintaining of flammable solvent,

nonflammable vapor blanket in combustion provided by non flammable solvent, such that vapor

from the flammable and nonflammable solvent form a non flammable gaseous mixture in the

blanket. Such method is used in removal of both oil-based polar contaminants to control the

flammability potential of an alcohol solvent. Since, it is miscible in water using water to

maintain its flammability is best way. For the mixture of ethanol and water, the water molecules

in the mixture vaporize along the length of the flame during combustion, it restricts the speed

and length of the flame but it has no contribution of the combustion. In addition to the

maintaining the flammability of ethanol, it improves the consumption of the fuel. For the case of

household cooking, mixing ethanol with water is a mechanism in order to reduce its flammability

since it is flammability in volume ratio up to ethanol 20 %.

The oxygen-balance or an expression used to indicate the degree to which an explosive can be

oxidized of ethanol is -208.7 %, which is far from other cooking fuels such as methane (CH4), is

-4 %, gasoline (C8H18) is -3.5 %, and kerosene (C10H22) is -3.5 %. But, when the percentage of


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water increased and the percentage of ethanol reduced in mixture case the oxygen-balance

negatively reduced and this is the percentage reduction of explosiveness. The oxygen-balance of

explosive molecule of zero is that all carbon atoms of the fuel convert to carbon dioxide, all

hydrogen atoms of the fuel is converted to water, all sulfur of the fuel to sulfur dioxide, and all

metals to metal oxides with no excess and is called zero oxygen-balance. The negative oxygen-

balance means the compound contains less oxygen than need and in reverse case having of

excess oxygen than the need one.

Ethanol is one of clean fuels that used in the house hold energy consumption for cooking. Even if

the energy content of ethanol is lower than gasoline, it is high flammable than gasoline and thus

impossible using of ethanol- gasoline mixture in open air whether cooking or other purpose.

However, their blend is commonly used for engines of vehicles in a closed carburetor. Now

days flex-fuel vehicles (FFV) with some engine modification are more developing through the

world. This accommodates the application ethanol in wider range as fuel for vehicles.

2.2 Ethanol- water mixture

Solution may be binary or tertiary and so on accordingly the number of substances to be

contributed in mixture. In a solution, substance present in a large quantity is called solvent and

the other to be solute in the arbitrary convention at known temperature and pressure. For the

binary solution formed by ethanol and water, nomenclature of solvent and solute reversedepending on the relative amount one two. If the mixture is formed equal amount of two

quantities, the nomenclature of solvent and solute left in the wish of experimentalists. Solution is

physical bonding of molecules of two or more either solid or liquid soluble quantities mixing in

one space of they occupy.

The solubility of mixture depends on either of molecular interaction force (attraction or

repulsion) and/or thermodynamic functions. Ethanol and water are completely miscible in to

each other in all proportion. The explanation for this is given by the fact that water-ethanol

attraction force is stronger than that of water-water and ethanol-ethanol interaction. That is the

interaction force between water and ethanol are predominantly dipole-dipole and hydrogen

bonding. In thermodynamic relation of mixture, any dissolution processes the free energy change


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must be negative that is the process must be exoergonic. This implies that the free energy of

solution must be less than the free energy of solute and solvent. All values of ethanol-water

mixture the mixture enthalpy is negative as shown section 2.3.3, and the small mixing

temperature and entropy, the free Gibbs energy of is always negative.

Therefore, the right dissolution of two mixtures, to get negative free energy of solution, there

must be either higher negative or exothermic mixing or there to be higher positive randomness of

solution.

The other principle for solubility is like dissolves like principle and usually based on phase

similarity. This usually indicates that similar materials with similar property dissolved one by

another.

Since, the molecules of ethanol are much smaller than water molecules in the solution of ethanol-

water mixture, so when the two liquids are mixed together the ethanol falls between the spaces

left by the water thus reduction of volume than the sum volume of two quantities. It's similar to

what happens when you mix a liter of sand and a liter of rocks. You get less than two liters total

volume because the sand fell between the rocks, right? Intermolecular forces (hydrogen bonding,

London dispersion forces, and dipole-dipole forces) also play their part in miscibility, but that's

another story.

The great similarity of the two molecules and hydroscopic attractive property of ethanol, ethanol

and water are complete miscible to each other solutions thus the water molecules (H2O) and

ethanol molecule (CH3CH2OH) are interchangeable arrangement in the solution. The molecules

are in sense "dumb" and can't distinguish one from the other since both are colorless and there to

be no possible limit for concentration of water in ethanol or ethanol in water.

The boiling point temperature of pure ethanol is 78.5 oC and the boiling point temperature of

water is 100

o

C, thus the boiling point temperature of ethanol-water mixture is between 78.5

o

Cand 100 oC. But from the experimental determination the boiling point temperature decrease

linearly up to ethanol-water mixture of 95.6 % in volume ratio (at 78.2 oC), then increase again

linearly to the boiling point temperature of pure ethanol. This is the unique property of ethanol in


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water solution. Since ethanol and water forms non-ideal mixture, the vapour pressure of vapour

composition is large positive deviation from Raoult's Law between liquid compositions during

boiling of ethanol water mixture. The occurrence of week hydrogen bonding is responsible for

large deviations in the random distribution of molecules that commonly used equations of state

and liquid solution models are not able to describe.

2.3 Determination of ethanolwater mixture ideal property

The property of ethanol-water mixture is different from property of pure ethanol or pure water .

Boiling point, density, flammability, flash point and freezing point changed accordingly the mole

fraction of both quantities in the solution. To come-up with the correct numerical value of

property of the mixture some correlations may used or in other case the experimental data values

used. Knowing of both physical and chemical property of substance is the initial step to put the

material as important and selective for the specific applications. The properties may be either in

ideal or non-ideal property.

2.3.1 Boiling point pressure and temperature

The boiling point temperature is an important property for the ready combustion and continuous

burning property of the fuel. Considering the ethanol-water mixture as ideal in its vapour

pressure, total solution pressure is the sum of molar partial pressure of ethanol and water. The

partial molar pressure of ethanol and water and it is a linear relation with vapor pressure in pure

case of each. The relation is stated as the equations shown below ;

Pwater= Powaterxwater

Pethanol= Poethanolxethanol

Therefore, the total pressure of mixture ethanol and water is to be the sum of partial molar

pressure of both components.Pmixture= Pwater+ Pethanol


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Figure 2-1: Ideal case partial pressure of ethanol, water and ethanol-water mixture

Table 2-1: Physical Properties of ethanol and water

Value Units Ethanol Water

Liquid density g/mL 0.789 1.000

Vapour density @ 95o

C g/mL 0.0015 0.001Molecular weight g/mol 46.0634 18.0152

Liquid Heat Capacity J/gK 2.845 4.184

Heat of Vaporization J/g 855 2260

Vapour Pressure @ 90oC torr 1187 525

Antoine formula for the relation of temperature and saturation pressure

ln (Psat) = A - B/ (T+C): Psat (kPa) T (oC) (2-2)

where:

A, B, and C are Antoine constants and listed in table below.

0

1

2

3

4

5

6

7

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

SaturationpressurekPa

Relation of Saturation Pressure of mixture and ethanol mole fraction

P ethanol P water P mix


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Table 2-2: Antoine constants of water and ethanol

Species of solution A B C

Ethanol 16.6758 3,674.49 226.45

Water 16.2620 3,799.89 226.35

The actual partial pressure relation of ethanol and water mixture is determined by using of

Antoine relation of temperature and pressure. Experimental data of ethanol and water mole

fraction in both liquid and vapour case up to the azeotropic point (95.6 %) of ethanol, the relation

of mole fraction and boiling point temperature developed [Annex C].

2.3.2 Fraction distillation of an azeotrope of ethanol-water mixture

Deviation of partial molar quantities of solution comparing with pure case of individual, solution

may classify as either ideal or non-ideal solution. Ideal solution, there is no change of partial

molar quantities (volume, internal energy and/or other quantities) of mixture and is completely

satisfy the Raoults Law with zero deviation in both liquid and vapour composition state in both

pressure and temperature. In other case Non-ideal solution is there is quite positive or negative

change of partial molar quantities (volume, internal energy and/or other quantities) of mixture

compared with pure state. Changes of partial molar quantities of liquid and vapor composition

during boiling and is not satisfied with Raoults Law of solution.

The relation of vapour and liquid concentration with the boiling point temperature varies. It deals

that at certain point temperature the composition of liquid phase and vapour escaped from the

liquid surface except the azeotropic point. But at the azeotropic mixture of ethanol-water

solution, the concentration of liquid and vapour escape from the liquid surface is identical (i.e. x1

= y1 = x2 = y2) and hence by method of fractional distillation is impossible to separate in to the

individual mixture component.. That is we called liquid-vapour equilibrium (LVE) property of

ethanol-water solution.

The minimum boiling point temperature (78.2 oC) ethanol-water mixture attained at the

concentration 95.6% by mass ratio. Fractional distillation used to reduce the water content after


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fermentation process produces 95.6 % concentrated ethanol by mass which is an azeotrope

mixture having boiling point of 78.2 C . If the solution with the azeotropic composition is

heated then vaporization takes place in such a manner that the relative amount of two

components are identical in the vapour and liquid phase.

Similarly, the freezing point temperature of ethanol-water mixture is between the freezing point

temperature of ethanol (-114.3oC) and the freezing point temperature of water (0 oC). Mixing

ethanol and water to make it safe for household use the ratio above 50 % ethanol usually the

freezing temperature below -32 oC and since there is very far of freezing point temperature than

usual ambient condition, no usual freezing problem of mixture. However, the density of mixture

varies with temperature, for all case its variation is only within the density of ethanol and water

[12].

At the azeotropic concentration, the mole fraction of liquid and vapour in each quantity is equal.

That means for example, the liquid and vapour mole fraction of ethanol or water is equal in

ethanol-water mixture.

The azeotropic concentration of binary liquid solution of solute is determined by using the

equation 2.5 below.

1

x1az= 1 +

lnPaz

P1satln Paz

P2sat

(2-3)

Where:

o P1sat is saturation pressure of solute

o P2sat is saturation pressure of solvent

o Paz is pressure of mixture at azeotropic point

2.3.3 Enthalpy of mixing

Enthalpy of solution or enthalpy of mixture for a binary solution is measured using a suitable

calorimeter. Here it is not possible to determine the absolute value of total enthalpy of solution or


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the mean molar enthalpy rather we have to use the thermodynamic relation to calculate the

change in partial molar enthalpy. The enthalpy change accompanying the formation of (n 1 + n2)

mole mixture is calculated as follows;

H mix = n1H1, m + n2H2, m (2-4)

For a liquid-liquid solution of enthalpy of mixture per mole is:

H (n1+ n2) mix = x1H1, m + x2H2, m

= x1H1, m + (1- x1) H2, m

H (n1+ n2) mix = x1(H1, m - H2, m) + H2, m (2-5)

Where:

Hm=H , mean mole enthalpy

The Enthalpy of Solution is the heat change which takes place when one mole of a solute is

completely dissolved in a solvent to form a solution of concentration measured under certain

conditions. Enthalpy of Solution can be measured experimentally. It can also be calculated; it is

the sum of two imaginary steps: the reverse of the lattice enthalpy plus the sum of the hydration

enthalpies of the ions.

The mixing process of ethanol and water is exothermic process and energy released to form

alternative bonding between ethanol and water. The relation of mixture enthalpy and mole

fraction of ethanol and water shows that increasing mixture enthalpy up to 15 % ethanol in

mixture and the decrease linearly. Therefore the maximum energy release (-780 J/mol) occurs at

15 % ethanol in water mixture.

Since ethanol-water mixture is non-ideal solution, the calculated value of equation 2-5 cannot

match with the real data of mixture enthalpy. The excess Gibbs energy is as the correction factor

between the experimental and analytical values. The real experimental data of mixture enthalpy

of ethanol-water mixture at STP is plotted in figure 2-2 below [13]. When two miscible liquids


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are mixed, a positive or negative heat effect occurs, which is caused by the interactions between

the molecules. This heat effect is dependent on the mixing ratio. The integral mixing enthalpy

and the differential molar mixing enthalpy can be determined by calorimetric measurements of

the heat of reaction.

Figure 2-2: Mixing enthalpy of ethanol-water mixture [12]

The temperature change when known amounts of water and ethanol mixed was determined; this

is the enthalpy change in an isothermal and isobaric environment. Agreeable data was found by

analytically and compared to similar experiments. Since waters structure and unique properties

affect many aspects of a solution, the solutions enthalpys decreased at a certain time due to

ethanols non-electrolyte nature. All the values of ethanol-water mixture enthalpy are negative

and which shows that Gibbs free energy to be negative for all temperature values and this

indicates the miscibility of ethanol and water.

-900

-800

-700

-600

-500

-400

-300

-200

-100

0

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

0.97

Mixitureenthalpy

J/mol

% mole fraction of ethanol-water mixture


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2.4 Partial molar volume

If you add 50 mL of water to 50 mL of water you get 100 mL of water. Similarly, if you add 50

mL of ethanol (alcohol) to 50 mL of ethanol you get 100 mL of ethanol. But, if you mix 50 mL

of water and 50 mL of ethanol you get approximately 96 mL of liquid, not 100 mL why?

First, the molecules of ethanol are much smaller than water and thus they filled with the space

left between water molecules just as mixing of fine sand and larger stone. In the other case, the

intermolecular force of ethanol-ethanol or water-water is less than that of ethanol-water or water-

ethanol. Mixing of known concentration is prepared by mixing calculated quantities of the two

substances and the density of each mixture is accurately measured.

From Eulers theorem of homogeneous mixture is related as;

V = n1(Vn1) + n2 (

Vn2) is volume of mixture

= n1V1, m + n2V1, m

Vm =V

n1+n2=

w1+w2

12(n1+n2)is the mean molar volume

V =V

n1+n2= (

w1+w2

X1M1+X2M2)(X1V1, m + X2V2, m) (2-6)

Where:

M- is the molar mass

w-is the mass of the components

Therefore, by using of the simplified formula based on only known quantities, in equation 2-6

above, the volume of mixture is calculated and for the sum volume of two quantities there is little

depression of volume. Thus, change of volume of sum volume of two quantities and mixture

volume with the mole fraction of ethanol in the ethanol-water mixture relation shown in figure 2-

3 below.


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Figure 2-3: The calculated volume change of 10 mL sample

2.5 The maximum flame temperature

When fuel burns definite amount of products are formed and a definite quantity of heat is

librated by breaking down of molecules of the fuel. This quantity of heat may be utilized to rise a

temperature of the products of combustion sufficiently to produce a flame. This temperature is

called maximum flame temperature or calorific intensity.

In the case, experiment is performed at a constant pressure of combustion then heat librated is

denoted by (Hc) and maximum temperature attained is the flame temperature or usually calledadiabatic flame temperature. The measurement of adiabatic is the combustion is absolutely

adiabatic with no loss of heat. The fuel maximum flame temperature calculated by considering

simple steady-state thermal energy balance can be constructed around a constant-pressure

combustion system by using first law of thermodynamics. However, measuring and construction

of adiabatic chamber to get maximum flame temperature is so difficult practically

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

Excessvolume

(mL)

Volume change with ethanol mole fraction


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Figure 2-4: Combustion model of controlled system

The energy balance about the combustion of fuel in controlled system can be written as:

CV + HR = Qc + Hc + HP (2-7)

Where:

- CV- calorific value of fuel

- HR-sensible heat of reactants

- Qc heat loss through the combustion chamber

- Hc useful heat or heat of total reaction or enthalpy of combustion

- HP Heat loss of flue gas

HR, the sensible heat in the air and fuel (ref. @ 25 oC) is very small since it is in equilibrium

with the environment and often neglected. The case heat loss from the outside of the plant, QC is

may be conduction, and convection loss through the combustion chamber and loss due to flue

gas is to be zero for the adiabatic assumption case. So, by using heat of reaction or useful outputheat by heat of combustion, we can determine the maximum flame temperature using equation

(2-7) by rewriting of equation 2-8.


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= = ,21 (2-8)

Where:

o T1 is the initial reference temperature

o Tf is maximum flame temperature

o is sum of heat capacities of all species present in system after reactioncomplete

Based on the property, initial temperature and composition of the fuel, the maximum flame

temperature to be determined accordingly equation (2-8).

For the reaction of pure ethanol (equation 2-1) is modified for mole balance and then in mass

relation is as follows;

C2H5OH + 3(O2 + 3.76 N2) 2CO2 + 3H2O + (3x3.76) N2

From this relation of balanced equation, again the mass balance is:

1 Kg C2H5OH +2.087 Kg O2 + 6.86 Kg N2 1.91 Kg CO2 + 1.17 Kg H2O + 6.86 Kg N2

The procedure of calculating the adiabatic flame temperature of fuel by straightforward method

is;

1) Evaluate the initial energy values of the fuel (CV and HR); But for this

calculation, assuming the initial temperature change of reactants is zero i.e.

HR=0.

2) Guess the value of Tf and use this value to find the specific heat of combustion

products at the average between that value and the reference temperature i.e. [(Tf

+ 25)/2] oC

3) Solve by using equation (2-7).4) Compare the new value of Tf with the original estimated and if there substantial

difference, use the new value to re-evaluate the specific heat, looping back to

equation (2-7) until satisfactory convergence is achieved. This is for the


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calculation accuracy for that the specific heat of flue gases is change with

temperature difference.

From the relation of equation (2-8) the right side is the high calorific value of ethanol at a

standard temperature and pressure (298.15 K and 1atm) is 29,700 KJ/Kg and the left side issummation of heat capacities of all species present in combustion of ethanol. Simplified relation

for maximum flame temperature is;

Tf = T1 +CV

mCpm

For initial guess of Tf =700 oC, thus the specific heat Cp of products is;

CO2 = 1.230 KJ/Kg

o

C H2O = 2.264 KJ/Kg

oC

N2O = 1.159 KJ/KgoC

= 1.911.230 + 1.17 2.264 + 6.861.159 = 12.949

Tf =2591.8 K = 2318.65 oC

And the mean temperature of the flue gases to be [(2318.65 + 25)/2] oC =1155.32 oC and the

specific heat at that temperature is;

CO2 = 1.316 KJ/KgoC

H2O = 2.564 KJ/KgoC

N2O = 1.237 KJ/KgoC

= 1.91 1.316 + 1.17 2.564 + 6.86 1.237 = 14.009

Tf = 2419.7 K = 2146.6 oC there is no more difference come in further iteration.

Therefore the adiabatic flame temperature of ethanol is 2146.6 oC. This value is more accurate

and close to measured value or data, than the theoretical data it is best in my opinion.


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2.6 Flammability of ethanol-water mixture fuel

In the chemical reaction of ethanol in air one mole of ethanol react with three moles of air, two

moles of carbon dioxide and three moles of steam produced as equation (2-1) stated above. The

stochiometric air quantity is the minimum amount of air needed for the complete conversion of

fuel to its product gases. But for most cases to achieve satisfactory complete combustion, some

quantity of excess air is used. However, the excess air used for combustion may get as product in

the product side that reduces the combustion heat and further reduces flame temperature.

Ethanol is very flammable with very low flash-point (~15 ) and has been used in Brazil andSouth Africa as cooking fuel. However generally it is used (85 % v/v) and higher concentration

and is a dangerous fuel and many fire deaths have been reported in its use at those

concentrations. For the mixing of incombustible water to ethanol the water at the reactant side is

converted to steam and as flue gas at the product side together with the product of ethanol

combustion steam. Flash-point is clearly decreased with increasing water content in the mixture

and this makes volatile ethanol safe for cooking. Therefore, when the content of water in the

mixture increase, the quantity of flue gas increase thus the quantity of heat librated is reduced

also the temperature of flame is again reduced.

To determine the stochiometric air of the mixture of ethanol and water for example, 50 %

ethanol-water solution fuel, since there is 50 % (v/v) ethanol in ethanol-water mixture and 21 %oxygen in air in the balanced equation of C2H5OH + 3O2 2CO2 + 3H2O: 1/0.50 = 2.0

Volumes of ethanol-water mixture requires 3/0.21 = 14.285 volumes of air, Or, one volume of

ethanol-water mixture requires 14.285/2.0 = 7.1428 volumes of air or in percentage relation

(1/(1+7.1428) = 0.1228 =12.28 %). This is ethanol-water mixture in air (stochiometric air

requirement of ethanol mixture).

Every fuel has its upper and lower flammability limit. The upper flammability limit (UFL) is the

highest percentage limit of fuel in combustion air that is still flaming and the lowest flammabilitylimit (LFL) is the lowest percentage of fuel in air that the flaming end. The similar calculation of

above, flammability of pure ethanol is 6.54 % and shown the flammability of 50 % ethanol-water

mixture is 12.28 %. That means the flammability is reduced by half. Ethanol will burn over wide


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range of flammability from the lower flammability level (LFL) of 3.3 % to the upper

flammability level (UFL) is 19 % ethanol in air [14].

The flame temperature of different percentage ethanol-water mixture is depends on the

percentage increase of Stochiometric Volume of air for unit volume mixture of fuel andStochiometric volume percentage of air in constant pressure combustion process. Having of

solution with the water content, the temperature is reduced due to in the reduction of generated

heat to evaporate water content of mixture and increase of volume percentage of stochiometric

air. For that, the relation of maximum flame temperature for the volume percentage ethanol-

water mixture is product of Volume % fuel, Volume % air, Peak Temperature (oC), and Peak

Pressure (atm) [15]. The peak temperature is the maximum temperature of ethanol-water solution

in pure case which calculated in previous section. The calculated values of maximum flame

temperature of ethanol-water mixture are summarized in table 2-3 below.

Table 2-3: Maximum flame temperature and % of ethanol-water mixture

Percentage of

ethanol-water

mixture

(% v/v ratio)

Stochiometric

Volume of air for unit

volume mixture

Stochiometric volume

% of air

Maximum flame

temperature(oC)

50% 7.1428 87.72 941.49

60% 8.571 89.55 1153.37

70% 9.9995 90.90 1365.88

80% 11.428 91.95 1579.04

90% 12.856 92.78 1792.45

95.0% 13.570 93.136 1899.29

100% 14.285 100 2146.6


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2.7 Activity coefficient ethanol-water mixture

In chemical thermodynamics, activity (symbol a) is a measure of the effective concentration of a

species in a mixture, and meaning that the species chemical potential depends on the activity of a

non-ideal solution in the same way that it would depend on concentration for an ideal solution.

By convention, activity is treated as a dimensionless quantity, although its actual value depends

on customary choices of standard state for the species. The activity of pure substances in

condensed phases (solid or liquids) is normally taken as unity. A solute in dilute solution is more

usual to express the composition of the solution of the solute which shows ideal behavior (also

referred to as "infinite-dilution" behaviour). Activity depends on temperature, pressure, and

composition of the mixture among other things [16]. The difference between activity and other

measures of composition arises because molecules in non-ideal gases or solutions interact with

each other, either to attract or to repel each other.

Activities should be used to define equilibrium constants but, in practice, concentrations are

often used instead. The same is often true of equations for reaction rates. However, there are

circumstances where the activity and the concentration are significantly different and, as such, it

is not valid to approximate with concentrations where activities are required.

The chemical potential of ith component in a liquid non-ideal solution is

i= o + RTlnai (2-9)

Where:

o o -is chemical potential of ith component in pure case of solution or it is standard

value at temperature T,

o R -Is gas constant, R=8.31J/K mol

o ai -activity of ith component

o RT*lnaiis excess Gibbs energy (excess chemical potential)


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We can find the activity of a component of a non-ideal solution from measurements of the vapor

pressure of that component in the vapor in equilibrium with the solution. We know that the

chemical potential of a component must be the same in the vapor as in the liquid.

il = og

i = ol + RT lnai = og + RT ln(PiPo ) (2-10)

Therefore, ai =pi

po

Where:

o is actual vapor pressure ando is the vapor pressure of the pure liquid

The ratio of activity to mole fraction of i component in a solution is called activitycoefficient:

= ai/xi and for ideal solution = 1 (that means the activity each element contributes as equal as

mole fraction) and for non-ideal solution may be either greater than one (positive deviation) or

less than one (negative deviation).

Sometimes it is convenient to write the activity as the product of an ideal part times a non

ideality correction part. For example, in a non-ideal solution we might write,

= x In the case of a non-ideal solution i 1 as xi 1 when the solution going to the ideal

approximation. That, and from which we can conclude that for a non-ideal solution,

i =Pi

xiPi=

actual vapor pressure

Raoults law vapor pressure

Activity coefficient is a fundamental thermodynamic quantity which measures the solution non-

ideality and is as a correction factor to the Raoults law, governs dilute range fluid-phase


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equilibrium. Predicting of the activity coefficient of ethanol-water solution by using UNIFAC

model based on the above relation at temperature of 298 oK is plotted in figure 2-5 below. From

the graph below, the activity coefficient of ethanol and water is equal at the mole fraction of

x=0.4 accordingly the UNIFAC model prediction. Above the mole fraction of ethanol (x=0.4)

the activity coefficient of ethanol is less than that of water is a dilution range of ethanol-water

mixture.

Figure 2.5: Activity coefficient of ethanol-water mixture by UNIFAC [17]

2.8 Flash point of ethanol-water mixture Analytical estimation

The flash-point of a given liquid is the experimentally determined temperature adjusted to

standard sea-level atmospheric pressure of 760 mmHg (0.1 MPa) at which substance emits

sufficient vapour to form combustible mixture with air.

Mathematically, flash-point is the temperature at which the vapour pressure is equivalent to the

lover flammability limit in the air.

= ()/

0

1

2

3

4

5

6

7

8

9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Activitycoefficient

The UNIFAC model -mole fraction of ethanolrelation

ethanol

water


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Where:

Psat(Tfl) is vapour pressure at the flash-point temperature (KPa)

P is ambient pressure (KPa)

The flash-point of binary solution is determined by the formula developed by Liaw et.el [18]

x i i Psat iPsat (Tfl)i

1 = 1 (2-11)

Where:

xi is mole fraction of components of mixture

i is activity co-efficiency of components of mixture

The above equation is re-witted for the binary mixtures of ethanol and water mixture is as:

xeePsat e

Psat(Tfl)e+

xww Psat w

Psat(Tfl)w= 1

A binary aqueous mixture contains water and flammable ethanol, water is non-flammable

component and therefore has no flash-point (Tfl). The prediction is equation is reduced from the

original Liaw model for the saturation pressure ethanol is:

Psat e =Psat (Tfl)e

xee (2-12)

The saturation pressure of with the mole fraction of ethanol in water solution is estimated by

using the Antoines relation of section 2.3.1. Therefore, from the relation of equation 2-12, the

saturation pressure of ethanol in the water solution at flash-point linearly related by the ethanol

mole fraction and activity coefficient.


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3.1 Potential and quality of ethanol production in EthiopiaIn Ethiopia, Over eight million liters of ethanol is being blend with petrol at the Sululta mixing

depot adding that efforts being made to enhance blending are vital to promote the culture of

using blended petrol. This blending has saved since 2008 over $10 million of total spends around

$ 1.1 billion annually to import fuel for its consumption by blending nearly 13 million liters of

ethanol with over 245.2 million liters of benzene. Sugar factories in our country produce ethanol

and private investors are also encouraged to engage in the production, which is vital to ensure the

countrys energy security [The Ministry of Mines and Energy, 2009].

The main ethanol source in Ethiopia is a co-production of sugar in majorly sugar factories by

fermentation of molasses. The quantity of production capacity is high enough for the use of

ethanol for cooking As well as blending of it for vehicles fuel. At the beginning of 2009, for the

five year plan of Ethiopia water and energy minister, with the production of sugar factories and

private factories the country will able to produce over 180 million liters of ethanol in each year

[19].

The main area of ethanol production in Ethiopia and its production capacity is listed in table 3-1

below.

Table 3-1: Ethanol production capacity of Ethiopia (1000 liters) [19]

Ethanol co-

product of sugar

2006/7 2007/8 2008/9 2009/10 2010/11 2011/12

Fincha 8,000 8,000 17,000 18,600 18,600 18,600

Wonji/shoa 12,245 17,809 20,836 25,153 25,153

Metehara 17,676 21,301 24,480

Tendaho 23,296 47,508 64,051 60,616

Total 8,000 20,245 58,105 104,620 129,106 128,849


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As table 3-1 above shows, Ethiopia has the capacity to produce more than 120 million liters of

ethanol production in each year since 2010.

There also increasing of ethanol production thus it is a co product of sugar. Therefore, ethanol

usage must be motivated in Ethiopia and ethanol using stove development and optimizing itshigh flammability to the safe range by mixing with non-flammable liquid is inevitable and award

research to go with state product. The production quality ethanol Fincha is 99.7% ethanol and

others are 94.6 % ethanol.

The low viscosity, absence of tendency of gumming and formation of soot in ethanol makes it a

more attractive possibility for cooking. Ethanol can be produced locally from a variety of

materials that can be classified as sugar-containing (e.g., sugar cane and sweet sorghum), starch-

containing (e.g.; maize and grain sorghum), and cellulose-containing (e.g.; wood and crop

residues). In Ethiopia, ethanol can be produced inexpensively from sugar cane and molasses at

different sugar factories as shown table 3-1. Thus, the low cost and abundant availability of raw

materials for the production of ethanol will make it very competitive with the other fuels used for

cooking.

3.2 Ethiopia Policy toward using of ethanol as cooking fuel

Ethanol to be used as a cooking fuel in rural household, the policy to be addressed is;

1. The government of Ethiopia allows ethanol to be used as a cooking and automotive fuel

blending with gasoline according to information from the Ethiopia energy ministry, since

2008, the nation has saved over $10 million by blending nearly 13 million liter of

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