AN EXPLORATORY STUDY OF A LIQUID DESICCANT WATERFALL SYSTEM FOR THE MALAYSIAN HUMID CLIMATE BY IHAB FAISAL IBRAHIM AHMED A dissertation submitted in fulfilment of the requirement for the degree of Master of Science in Building Services Engineering Kulliyyah of Architecture and Environmental Design International Islamic University Malaysia DECEMBER 2013
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AN EXPLORATORY STUDY OF A LIQUID DESICCANT WATERFALL SYSTEM FOR THE
MALAYSIAN HUMID CLIMATE
BY
IHAB FAISAL IBRAHIM AHMED
A dissertation submitted in fulfilment of the requirement for the degree of Master of Science in Building Services
Engineering
Kulliyyah of Architecture and Environmental Design International Islamic University Malaysia
DECEMBER 2013
ii
ABSTRACT
An exploratory study of a liquid desiccant waterfall (LDW) system was conducted as a means of achieving air dehumidification of an internal air environment. The aim is to explore an alternative technology which can reduce energy consumption, while still achieving acceptable thermal comfort conditions and achieving specific advantages when compared with conventional air conditioning systems. Some of these advantages include the pleasing aesthetics and appearance of a waterfall feature, the efficient functionality behind desiccant dehumidication technologies of the LDW system. This study and research proposed a system which harnesses hygroscopic salt of lithium chloride (desiccant) in its liquid form (45% concentration). This naturally attracts and absorbs moisture from an internal environment. Having absorbed the moist indoor air into the system, the lithium chloride then converts into a diluted form (30% concentration) and this requires the solution to be reactivated. A further advantage of the LDW system is explored representing significant potential in saving energy through the harvesting of solar thermal energy in order to expel moisture out of the system, as well as to efficiently reactivate the saline solution of lithium chloride to undertake its the cyclic nature of new dehumidification processes. To further quantify the amount of moisture to be absorbed by the LDW system and to some extent verify this exploratory study, a case study of a hypothetical space of an open plan office building in Kuala Lumpur city was proposed. The study then calculates the total amount of moisture to be eliminated by the LWD system (as specified by the common standard) was 25.4 kg/hr based on standards of thermal comfort for an office environment. Life cycle costs and energy savings were estimated. The results demonstrate and suggest a high prospect in creating an attractive financial return-on investment (ROI) including energy savings. When design optimally, this technology or system can save up to 92% of energy consumption and offer an investment rate of return of 34% per year. This was considered an attractive investment because it could offer reasonable payback period of 3 years.
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ملخص البحث
شلال صورة في السائلة اففات لنظام تفصيلية تصميم دراسة العلمي البحث اهذ يتضمن الرطوبة لازالة تحكم كوسيلة ليستخدم النظام هذا تصميم الي الوصل تم وقد. داخلي مائي
استخدام من المتسببة المشاكل على والتغلب لازالة المثلى الحلول من ويعتبر ,بالجو العالقة واستهلاك هدر من عالية نسبة تشمل التي و التقليدية التبريد اجهزة او الهواء تكيف انظمة الهواء جودة مستوى علي السلبي والتاثير الكهربائية الطاقة خصوصا والموارد للطاقة
أحدث كأحد النظام هذا في المميز الجمالي والشكل الحديثة التقنية بين الجمع تم .الداخلي الذي المائي الشلال صورة في النظام هذا طرح. المطورة سائلةال اففات تكنولوجيا اساليب مما %45 تركيز بنسبة كلوريد اليثيوم محلول في متمثلة اففة الكيميائية المادة علي يحتوي داخل في استيعاا و به المحيط الهواء في الموجودة الرطوبة طبيعية بصورة يمتص و يجذب يجعله نسبة الى كلوريد الليثيوم محلول تركيز ينخفض حتي النظام يعمل. داخليا لمعالجتها النظام
صورة في البديلة الطاقة باستخدام وذلك المحلول تفعيل لاعادة النظام يخول مما 30% توضيحي شرح تقديم تم كما . فاعلة و منتظمة بصورة عمله دورة ليواصل الشمسية الطاقة
مدينة في التصميم حديثة مكاتب علي يشتمل مبنى في النظام هذا عمل طريقة و لاستخدام تحقق بنسبة الجو من ازالتها المراد الرطوبة كمية لتحديد مربع متر 320 بمساحة لمبور كوالا والمواصفات المقاييس، المعايير كل الاعتبار في وضعا المساحة لمستخدمي الحرارية الراحة
25,4 بمقدار ازالتها المراد الرطوبة ةكمي تحديد و قياس تم قد و.عالميا عليها المتعارف و. عليها المتعارف المقاييس حسب الحرارية الراحة ظروف على للحفاظ ساعة / كيلوجرام
يضمن كما %92 بنسبة للطاقة توفيرا يحقق انه بما عالية مالية فاعلية النظام هذا اثبت قد فى منه الاستثمار اعادة يعنى مما سنويا % 34 بنسبة الاستثمار اعادة معدل النظام هذا
. فقط سنوات ثلاث فترة خلال
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APPROVAL PAGE
I certify that I have supervised and read this study and that in my opinion, it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Master of Science in Building Services Engineering.
I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Master of Science in Building Services Engineering.
................................................. Noor Aziah Mohd Ariffin Examiner
This dissertation was submitted to the Kulliyyah of Architecture and Environmental Design and is accepted as a fulfilment of the requirement for the degree of Master of Science in Building Services Engineering.
…............................................. Nurul Hamiruddin Salleh Head, Department of Architecture
This dissertation was submitted to the Kulliyyah of Architecture and Environmental Design and is accepted as a fulfilment of the requirement for the degree of Master of Science in Building Services Engineering.
…............................................. Khairuddin Abdul Rashid Dean, Kulliyyah of Architecture and Environmental Design
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DECLARATION
I hereby declare that this dissertation is the result of my own investigations, except
where otherwise stated. I also declare that it has not been previously or concurrently
submitted as a whole for any other degrees at IIUM or other institutions.
Ihab Faisal Ibrahim Ahmed
Signature …………………………………… Date ……………………..
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INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA
DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH
AN EXPLORATORY STUDY OF A LIQUID DESICCANT WATERFALL SYSTEM FOR THE MALAYSIAN HUMID CLIMATE
No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below.
1. Any material contained in or derived from this unpublished research may only be used by others in their writing with due acknowledgement.
2. IIUM or its library will have the right to make and transmit copies print or electronic) for institutional and academic purposes.
3. The IIUM library will have the right to make, store in a retrieval system and supply copies of this unpublished research if requested by other universities and research libraries.
Affirmed by Ihab Faisal Ibrahim Ahmed.
……………………………. ……………….. Signature Date
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ACKNOWLEDGEMENTS
First and foremost, i would like to express my sincere and grateful appreciation to my supervisor, Dr. Puteri Shireen Jahnkassim whom i am profoundly indebted to her support, encouragement, guidance and insightful discussions on this research. Her joy and enthusiasm in conducting this research were my supportive motivations and I will be forever thankful for being her student. Beside my supervisor, accomplishing this research would not have been possible without the assistance from Dr. Yousif Abakr, his valuable comments and remark which were my guidance to expand my knowledge in this research area.
Finally and most importantly, there are no words to convey my sincere acknowledgement to my precious mother, father and siblings for their unconditional love and spiritual support throughout my study. Ihab Faisal Ibrahim Ahmed
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TABLE OF CONTENTS
Abstract ............................................................................................................... ii Abstract in Arabic ................................................................................................ iii Approval Page ..................................................................................................... iv Declaration Page ................................................................................................. v Declaration of Copyright ..................................................................................... vi Acknowledgements ............................................................................................. vii List of Tables ....................................................................................................... x List of Figures ..................................................................................................... xii List of Abbreviations ........................................................................................... xiv CHAPTER ONE: INTRODUCTION .............................................................. 1
1.1 Introduction ....................................................................................... 1 1.2 Desiccant Dehumidification Technology ......................................... 2 1.3 The Liquid Desiccant Waterfall (LDW) System .............................. 3 1.4 Problem Statement............................................................................ 4 1.5 Research Aim and Objectives ......................................................... 4 1.6 Research Structure ............................................................................ 5
CHAPTER TWO: LITERATURE REVIEW ................................................. 9
2.1 Introduction ........................................................................................ 9 2.2 Desiccant Materials in Perspective...................................................... 9 2.3 Desiccant Material Studies ................................................................. 12
2.3.1 Background Studies on Solid Desiccant Materials ..................... 13 2.3.2 Background Studies on Liquid Desiccant Materials ................. 14 2.3.3 Previous Studies on Desiccant Mixtures .................................... 16
2.4 Practicability and Applications for Desiccants Technology ................. 16 2.5 Desiccant Performance ....................................................................... 17 2.6 Liquid Desiccant Waterfall Systems .................................................. 20 2.7 Summary ........................................................................................... 21
CHAPTER THREE: AIR VENTILATION REQUIREMENTS IN A HUMID CLIMATE .......................................................................................................... 23
3.4.1 Permeation and Infiltration through the Building Materials ....... 28 3.4.2 Infiltration through Miscellaneous Openings ............................. 30 3.4.3 Moisture from Occupants .......................................................... 31 3.4.4 Ventilation and Makeup Air ...................................................... 32
CHAPTER FOUR: SELECTION OF THE OPTIMUM DESICCANT SOLUTION ........................................................................................................ 36
4.1 Introduction ........................................................................................ 36 4.2 Investigation of the Liquid Desiccant Solutions .................................. 36
4.2.1 Equilibrium Vapor Pressure of the Liquid Desiccants ............... 38 4.2.2 Thermal Conductivities of the Liquid Desiccants ...................... 42 4.2.3 Dynamic Viscosity of the Liquid Desiccants ............................. 44 4.2.4 Specific Heat Capacity of the Liquid Desiccants ....................... 46 4.2.5 Safety Criteria of Liquid Desiccants .......................................... 49 4.2.6 Corrosion of the Liquid Desiccants ........................................... 50 4.2.7 Cost of Liquid Desiccants ......................................................... 51
4.3 Summary ............................................................................................ 52 CHAPTER FIVE: THE DEVELOPMENT OF THE LDW SYSTEM DESIGN ............................................................................................................. 54
5.1 Introduction ........................................................................................ 54 5.2 Quantification of Liquid Desiccant for the LDW System .................... 54 5.3 Development of the LDW System Components .................................. 62
5.3.1 The Waterfall Dehumidifier Feature.......................................... 64 5.3.2 Flat Desiccant Solar Collector System ...................................... 66 5.3.3 The Cooling Tower System ....................................................... 69 5.3.4 The Pumping System ................................................................ 71 Determining the Pump Power ............................................................ 77 5.3.5 The Control Panel System ......................................................... 78 5.3.6 Storage Tanks System ............................................................... 79
5.4 Air Circulation System ....................................................................... 79 5.5 Summary ........................................................................................... 81
CHAPTER SIX: ECONOMICAL VALUE AND LIFE CYCLE COST ANALYSIS......................................................................................................... 83
6.1 Introduction ........................................................................................ 83 6.2 Economical Value of the LDW System............................................... 83 6.3 Life Cycle Cost Analysis of the LDW System .................................... 84 6.4 Cost Analysis Comparison of the LDW System & AC System ........... 85
6.4.1 The Capital Costs ...................................................................... 86 6.4.2 The Operation Costs ................................................................. 86 6.4.3 The Maintenance Costs ............................................................. 86 6.4.4 The Disposal Costs .................................................................. 87
6.5 Summary ............................................................................................ 88 CHAPTER SEVEN: CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK ............................................................................................... 89
7.1 Main Achievements of this Work and Discussion ............................... 89 7.3 Recommendations and Future Work ................................................... 92
Table No. Page No. 3.1 The mean surface wind speed for 34 Years (1969–2003) 26
3.2 F1 Factor for Grain Difference 29
3.3 Evaporation Rates of People 31
4.1 Weighting Factor & Figures Of Merit for the proposed properties 37
4.2 The vapor pressure at the surface of proposed desiccant solutions at 25 oC and 30% concentration. 40
4.3 Equilibrium humidity ratio at the surface of some saturated solutions at 40oC 41
4.4 Thermal conductivities of the selected desiccant solutions at 25% concentration and 30 oC 44
4.5 Dynamic viscosity of the selected desiccants at 30% concentration and 25oC 46
4.6 Table 4.6: Specific heat capacity of the selected desiccant at 30% concentration and 25 oC 48
4.7 Safety criteria of the selected desiccant solutions 50
4.8 Corrosion rate of the proposed liquid desiccants 51
4.9 The cost of the selected desiccants per USD per kilogram of solution 51
4.10 The selection of the optimum desiccant solutions 53
5.1 The Vapor Pressure Of LiCl Based On Different Temperature & Concentration Level 59
5.2 The Vapor Pressure Of Specified Indoor Conditions 60
5.3 The Vapor Pressure Of Actual Outdoor Conditions 60
5.4 Sizing Of Suction Pipe 74
5.5 Equivalent Feet of Straight Pipe for Fittings 75
5.6 Friction Loss Multipliers 75
6.1 The Initial Cost Of The LDW System’s Components 85
xi
6.2 Cost Analysis Comparison For LDWS & AC System 87
xii
LIST OF FIGURES
Figure No. Page No. 1.1 Air dehumidification in conventional air conditioning system 2
1.2 The research’s structure 6
2.1 Diagrammatic representations of the vapor pressure role in desiccant cycle (Lewis and Harriman, 2002) 10
2.2 A schematic of Liquid Spray – Tower system (Bhatia, 2012 And Lewis, 2002) 12
2.3 Liquid desiccant waterfall of the University of Maryland (2011) 20
3.1 The average, minimum and maximum dry bulb temperature 24
3.2 The average, minimum and maximum wet bulb temperature 25
3.3 The average, minimum and maximum relative humidity 25
3.4 F2 Factor For Space Permation 30
4.1 Vapor pressure at the surface of (A) lithium bromide and (B) lithium chloride solutions for different temperature and concentrations (Mohammad, 2010) 39
4.2 Vapor pressure at the surface of (A) calcium chloride and (B) magnesium chloride solutions for different temperature and concentrations, (Mohammad, 2010) 39
4.3 Equilibrium humidity ratio at the surface of some saturated solutions (Linke, 1965 and Stephen, 1963) 41
4.4 Thermal conductivities of (a) lithium chloride and (b) calcium chloride under different concentration conditions (Mohammad, 2010). 42
4.5 Thermal conductivities of (a) magnesium chloride and (b) lithium bromide under different concentration conditions, (Mohammad, 2010). 43
4.6 Viscosity of (a) lithium chloride and (b) calcium chloride, (Mohammad, 2010). 45
4.7 Viscosity of (a) magnesium chloride and (b) lithium bromide, (Mohammad, 2010) 45
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4.8 Specific heat capacity of (A) lithium chloride and (B) calcium chloride solution under different temperature and concentration (Mohammad, 2010). 47
4.9 Specific heat capacity of (A) lithium bromide and (B) magnesium chloride solutions under different temperature and concentration (Mohammad, 2010). 48
5.1 Actual Condition In Kuala Lumpur city, ( ) Feasible Thermal Comfort Condition ( ) and ( ) the amount of moisture to be removed 55