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UMVPIStTY OF MMATUWA, SM UMtt 
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ANALYSIS OF EFFICIENCY IMPROVEMENT OF AIR 
CONDITIONING SYSTEMS: A CASE STUDY 
Thennakoon Mudiyanselage Dharmasiri Thennakoon 
(07/8407) 
Dissertation submitted in partial fulfillment of the requirements for the degree Master 
of Science 
University of Moratuwa 
102532 G S ^ ^ U 
Department of Electrical Engineering *G2l\ '^CP^^) 
University of Moratuwa 
Sri Lanka 
October 2011 JO 
102532 
DECLARATION 
"I declare that this is my own work and this dissertation does not incorporate 
without acknowledgement any material previously submitted for the Degree or 
diploma in any other University or institute of higher learning and^to the best of 
my knowledge and belief it does not contain any material previously published or 
written by another person except where the acknowledgement is made in the text. 
Also, I hereby grant to University of Moratuwa the non-exclusive right to 
reproduce and distribute my dissertation, in whole or in part in print, electronic or 
other medium. I retain the right to use this content in whole or part in future 
works (such as articles or books). 
I 
Date: 25-10-2011 
The above candidate has carried out research for the Masters dissertation under my 
supervision. 
Signature of the supervisor: Date: 25-10-2011 
Prof. Lanka Udawatta 
1 
ABSTRACT 
This research intends to study the principles and the concept of air conditioning set out by 
Wills Carrier and to look into the manner in which its discovery has changed the world we 
live in. It involves the study of various equipment used in air conditioning systems currently 
and the way they have evolved over time. The research primarily strives to recognize 
problems that can arise when using these machines, understand the reasons for various 
inefficiencies in their performance and the calculation of the energy losses that arise as a 
result. It then sets out the framework by which a solution to lessen such energy loss can be 
successfully arrived at. All activities of this research inclusive of the collection of data, the 
calculations made using these data and the identification of problems that surfaced, were 
carried out based on the air conditioning systems at the Lady Ridgeway Children's Hospital, 
Colombo. A successful effort has then been made in this dissertation to summarize the 
problems identified in the operation of these machines at the above mentioned site and to 
provide a comprehensive and viable solution. In doing so, the efficiencies of the A/C 
machines at the hospital have been calculated separately according to the ASHARE 
guidelines while calculations have also been made with some assumptions to ascertain the 
loss of energy on a daily basis due to deficiencies existing in these air conditioning systems. 
However, this research extends far beyond a mere effort to find the loss of energy from these 
systems at the Lady Ridgeway Children's Hospital and reduce such loss; the collective of 
information gathered and the solutions provided to the problems revealed through this 
collective extend the scope of this research to one with a wider authority. Further, this 
dissertation presents its facts and findings so that a correct understanding about the changes 
in the efficiencies of an air conditioning system and about the economic benefits accruing 
from the exertion of effective control over such changes is delivered to anyone who wishes 
to study it in depth. 
u 
DEDICATION 
The effort being made to successful end of this assignment will be dedicated to 
loving parents, who left me this world few years ago. 
111 
ACKNOWLEDGEMENT 
It is with deep gratitude that I thank first and foremost my supervisor, Prof. 
Lanka Udawatta, Department of Electrical Engineering, University of Moratuwa 
for the correct and unremitting guidance provided. His vivid insights and 
perspectives extended to me during this period and, not to forget, his senses of 
humor made this important task a resounding success. I thank him again 
sincerely. Further my heartfelt thanks go to the other academic staff of the 
department of Electrical Engineering, University of Moratuwa, whose numerous 
supportive efforts contributed to me for succeeding my MSc course. 
My sincere gratitude is very much extended to all the officers (and also the minor 
staff) of the Department of Electrical Engineering office including Mrs. Nayanie, 
who rendered their kind and fullest co-operation to me throughout my MSc 
course period. 
Also I would like to thanks my parents, brothers and sister for their constant 
encouragement provided to me to carry out this task, while bearing my absence 
in many of their activities. 
Finally, I would thank my friends and colleagues and other individuals, whom I 
have not mentioned in person, but without whose support I could not have made 
this educational process a success. 
iv 
TABLE OF CONTENTS 
Declaration i 
Abstract ii 
Dedication iii 
Acknowledgement iv 
List of Figures X 
List of Tables xii 
List of Abbreviations xiii 
1. Introduction 1 
1.1 History of Air Conditioning 3 
1.2 Background 3 
1.3 Motivation 5 
1.4 Objectives 5 
2. Theory, Systems and Internal Equipments of A/C technology 7 
2.1 Theoretical Background of the Air Conditioning Field 7 
2.2 Refrigeration and Second Law of Thermodynamics 7 
2.3 Psychometric Chart. 8 
2.4 Air Temperature and Relative Humidity 9 
2.5 Radiant Heat 9 
2.6 Refrigerants with Hydro Chlorofluorocarbon 10 
2.7 Principle of Insulation 11 
2.8 Air Conditioning Systems 14 
2.8.1 Room Air Conditioners 14 
2.8.2 Central Air Conditioners 14 
2.8.3 Unitary Air Conditioners 16 
2.8.4 Direct air Conditioning Systems 16 
2.8.5 Self- Contained Air Conditioning Systems 17 
2.8.6 Direct Expansion Systems 18 
2.8.7 All Water systems 18 
2.8.8 All air Systems 18 
2.8.9 Evaporative Coolers 19 
V 
2.8.9.1 Chillers and Chillers Systems 19 
2.9 Air Conditioning Equipments 20 
2.9.1 Air Conditioner Filters 21 
2.9.2 Air Conditioner Coils 22 
2.9.3 Coil Fins 22 
2.9.4 Types of Insulation Materials 22 
2.9.5 Bulk Insulation 22 
2.9.6 Reflective Insulation 23 
2.9.7 Codes and Standards 24 
Analysis of Efficiency of the Air Conditioning Systems. 26 
3.1 Air conditioner Efficiency 26 
3.1.1 Room Air Conditioners-EER 26 
3.1.2 Central Air Conditioners-SEER 27 
3.2 Energy Efficiency Cass in Cooling Mode of Newly Room A/C systems 27 
3.3 Energy Efficiency Cass in Heating Mode of Newly Room A/C systems 27 
3.4 Energy Labeling 28 
3.5 Energy Efficient Air Conditioning 28 
3.6 Fundamentals of Energy Efficient Design 29 
3.7 Comfort Condition and Human Environment 30 
3.8 Thermal Comfort Conditions 30 
3.8.1 Conditions and Properties to be Control or Improved 30 
3.8.2 Options for Improving Energy Efficiency of Building Envelop 31 
3.8.3 Hiring Professionals Service 32 
3.8.4 Choosing Contractor 32 
3.8.5 Installation and Location of Air Conditioner 33 
3.8.6 Sealing and Insulation Air Ducts 34 
3.8.7 Roof Moisture Inspections 35 
3.8.7.1 Sealing Windows 35 
3.8.7.2 Sealing Doors 35 
3.8.7.3 Sealing Around Joints 36 
3.8.8 Controlling Infiltration at Main Entrance 36 
3.8.8.1 Construction of Exterior Insulation and Finish Systems 36 
vi 
3.8.8.2 Sub Surface Heat Sources in the Building 37 
3.9 Regular Maintenance for High Efficiency A/C Systems 37 
3.9.1 Air Conditioning Problems 38 
3.9.2 Over Sizing Case and Effect for the Low Efficiency 38 
3.9.3 Moisture Builds up Case and Effect for the Low Efficiency 39 
3.9.4 Noisy Operation Case and Effect for the Low Efficiency 39 
3.9.5 Insulation Checks for High Efficiency 40 
3.9.6 Selecting Equipments with Manual S 41 
3.9.7 Proper Selection Consideration of Ac Systems 42 
3.9.8 Points to be Consider before Purchase and Energy Cost 42 
3.9.8.1 Verifications of Construction Details 43 
3.9.8.2 Sick Building Syndrome 44 
3.9.8.3 Design Conditions for A/C Spaces 44 
4. Calculation, Efficiency Analysis of A/C Systems at the Site 46 
4.1 Introduction about the Site 46 
4.2 Equipments of Main Air Conditioning System in the Site 47 
4.3 Insulation Problems in the Various Places 49 
4.4 Equipment Wise Problem in the Plant Room 52 
4.5 General HVAC Calculations for the Building 58 
4.5.1 Heat Load 59 
4.5.2 Factors Include in Heat Load calculations 60 
4.5.3 Flow Area of Room 60 
4.5.4 Window Size and Positions 60 
4.5.5 Occupants 61 
4.5.6 Equipments 61 
4.5.7 Lightings 61 
4.5.8 Building Walls 61 
4.5.9 Building Attic and Basement 62 
4.6 Building Heat Loads 62 
4.7 Total Cooling Required 65 
4.8 Example Air Conditioning Calculation at the Site 65 
4.8.1 Window and Splits Type Air conditioners Efficiency at the Site 74 
vii 
4.8.2 Package Type Air Conditioners Efficiency at the Site 79 
4.8.3 Central Air Conditioning System Efficiency of the Hospital 82 
4.8.3.1 Individual Chiller Efficiency 82 
4.8.3.2 Plant Efficiency 82 
4.8.3.3 Summary of the Hospital Electricity Bills 87 
4.8.3.4 Chemical Concentration of Water Used for LRH A/C 90 
4.9 Summery Calculation of the Efficiency and 
Energy Saving Amount at the Site 91 
4.9.1 Duct Sizing for Condition Air Distribution to Old Theaters 92 
5. Technology and Important Considerations for High Efficiency A/C 95 
5.1 New High Efficiency Technology Air Conditioners Technology 95 
5.1.1 What is Digital Scroll System 95 
5.1.2 Operation Principle of Digital Scroll Compressor 95 
5.1.3 Control Principle of Variable Capacity Systems 96 
5.1.4 Development of Digital Scroll Systems 96 
5.1.5 Properties of the High Efficiency Room Air Conditioners 96 
5.2 Compact Design Leading-Edge Technology 97 
5.3 Advanced Oil Return Technology 98 
5.4 Main Performance and Features of New A/C systems 98 
5.4.1 High Efficiency Conditioning Air Filtering 99 
5.4.2 Proper Sizing of Air Conditioners 99 
5.4.3 Buying New Air Conditioners 100 
6. Conclusions 101 
References 103 
List of Appendices 108 
viii 
LIST OF FIGURES 
ix 
Figure 2.1 Psychometric Chart 8 
Figure 2.2 Layout Diagram of Refrigeration Cycle 21 
Figure 4.1 The Lady Ridgway children's Hospital at Colombo Sri Lanka 46 
Figure 4.2 Equipments of the Main A/C System at the Site 47 
Figure 4.3 Chill Water Pump System at the Hospital 48 
Figure 4.4 Cooling Tower System at the Hospital 48 
Figure 4.5 Air Handling Units at the Hospital 49 
Figure 4.6 Internal View of the Operation Theaters of the Hospital 49 
Figure 4.7 Chill Water Distribution System of the Hospital 50 
Figure 4.8 Package Unit Internal View 50 
Figure 4.9 Damaged Air Blower 54 
Figure 4.10 Gland Damaged Condenser Water Pump 54 
Figure 4.11 Maintenance Errors of Condenser Pump 55 
Figure 4.12 Damaged Air Blower of the Fan Coil Unit 55 
Figure 4.13 Week Packing for the Evaporator 56 
Figure 4.14 Servicing Problems of the Fan Coil Units 56 
Figure 4.15 Servicing Problems of Cooling Towers 57 
Figure 4.16 Servicing Problems of Chilled Water Overhead Tanks 57 
Figure 4.17 Servicing Problems of Condenser Water Underground Tank 58 
Figure 4.18 Layer of the Wall 62 
Figure 4.19 Building Base 63 
Figure 4.20 Air Conditioning Room 65 
Figure 4.21 Load Calculation Diagram 71 
Figure 4.22 View of the Package Air Conditioner 79 
Figure 4.23 Cooling Towers for the Package Units 80 
Figure 4.24 Condenser Pump for the Package Units 80 
Figure 4.25 Main Compressor for the Central Chiller Plant 82 
Figure 4.26 Control Panels for Chillers 83 
Figure 4.27 Main Condition Air Blower of the Theater 85 
Page 
Figure 4.28 Main Power Meter for the Central Air Conditioning System 90 
Figure 4.29 Main Control Panel of the Power Supply to the Hospital 90 
Figure 4.30 Duct Arrangement 92 
x 
LIST OF TABLES 
Page 
Table 4.1 Thermal Conductivity Values 66 
Table 4.2 Heat Conducted Through the Wall 67 
Table 4.3 Conversion Factors - 1 73 
Table 4.4 Conversion Factors - II 73 
Table 4.5 Conversion Factors -III 74 
Table 4.6 Conversion Factors -IV 74 
Table 4.7 Conversion Factors -V 74 
Table 4.8 Parameters for the Ac Machine - I 74 
Table 4.9 Parameters for the Ac Machine -II 75 
Table 4.10 Parameters for the Ac Machine -III 77 
Table 4.11 Parameters for the Ac Machine - IV 81 
Table 4.12 Water Flow Rates to the AC Plant 85 
Table 4.13 Electricity Bill of the Hospital 89 
Table 4.14 Duct Line Data 93 
Table 4.15 Duct Size Equivalents 94 
XI 
LIST OF ABBREVIATIONS 
Abbreviation Description 
A/C Air Conditioning 
ACCA Air Conditioning Construction of America 
ASHARE American Society of Heating Air Conditioning and 
Refrigeration Engineers 
q Amount of Heat 
A Area 
AC Alternative Current 
BUR Build Up Roof 
BTU British Thermal Units 
COP Coefficients of Performance 
CEIFS Construction of Exterior Insulation and Finish 
Systems 
CMU Concrete Masonry Unit 
DC Direct Current 
dp Dew Point 
EER Energy Efficiency Ratio 
E Energy 
r| Efficiency 
h Enthalpy 
Q Heat 
HVAC&R Heating Ventilation Air Conditioning and 
Refrigeration 
HCFC Hydro Cloro Floro Carbon 
U Internal Energy, Overall Heat Transfer Coefficient 
Ql Latent Heat 
L Length 
LRH Lady Ridgway Hospital 
xii 
M Mass 
G Moisture Content of Air 
OFN Oxygen Free Nitrogen 
RH Relative Humidity 
C Specific Heat Capacity 
SEER Seasonal Energy Efficiency Ratio 
SHR Sensible Heat Ratio 
Qs Sensible Heat 
T Temperature 
k Thickness Thermal Conductivity 
R Thermal Resistant 
U Thermal Transmittance 
USA United State of America 
xiii 
LIST OF APPENDICES 
Appendix Description Page 
Appendix-A Definition of Terms Used in A/C field 108 
x iv