AIR-CONDITIONING SYSTEM
BY USING DISTRICT COOLING SYSTEM (DCS): THERMAL ENERGY STORAGE (TES) TECHNOLOGY
NORDIANA BINTI MOHD HATTA
“I admit that had read this dissertation and in my opinion this dissertation is satisfactory in the aspect of scope and quality for the bestowal of
Bachelor of Mechanical Engineering (Design and Innovation)”
Signature:
Name of Supervisor 1: Mr. Safarudin Gazali Herawan Date:
Signature :
AIR-CONDITIONING SYSTEM
BY USING DISTRICT COOLING SYSTEM (DCS): THERMAL ENERGY STORAGE (TES) TECHNOLOGY
NORDIANA BINTI MOHD HATTA
This report was submitted in accordance with the partial requirement for the honor of
Bachelor of Mechanical Engineering (Design and Innovation)
Faculty of Mechanical Engineering Universiti Teknikal Malaysia Melaka
“I verify that this report is my own word except summary and extract that every one of it I have clarify the resource”
Signature:
iii
ACKNOWLEDGEMENT
I would like to acknowledge and extend my heartfelt gratitude to the following persons who have made the completion of this Projek Sarjana Muda (PSM) report possible. I would like to express my deep and sincere gratitude to my supervisor, Mr. Safarudin Gazali Herawan, His wide knowledge and his logical way of thinking have been of great value for me. I am deeply grateful for his detailed and constructive comments, and for his important support throughout this work.
I wish to express my warm and sincere thanks to Mr. Amiruddin Ghazali, Head of Section of TNEC and Mr. Sharulnizam Shariff, Plant Supervisor of TNEC who gave me the opportunity to gain knowledge and experiences about the DCS and TES systems that wholly-liable under TNB Engineering Corporation (TNEC) and gave me untiring help during my difficult moments. I owe my most gratitude to Mr. Nazree Abdullah, Senior Technician of TNEC for his valuable advice and friendly help. Their extensive discussions around my work and interesting explorations in operations have been very helpful for my PSM.
v
ABSTRACT
vii
ABSTRAK
Kajian ini adalah mengenai sistem penyejukan udara menggunakan Sistem Pendingin Lingkungan (District Cooling System-DCS) dengan teknologi Tenaga Pendam Lakuran (Thermal Energy Storage-TES). DCS ialah sistem di mana pusat chiller plant membekalkan air sejuk untuk tujuan penyejukan bagi beberapa bangunan sekitar. Manakala TES adalah penyimpanan tenaga penyejukan pada waktu beban penyejukan rendah dan akan digunakan kemudian ketika tenaga penyejukan itu diperlukan. TES terbahagi kepada beberapa jenis iaitu ice harvesting, ice-on-coil, ice slurry dan encapsulated ice Sistem Ice-on-coil terbahagi kepada dua
ix
TABLE OF CONTENT
CHAPTER TITLE PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vii
TABLE OF CONTENT ix
LIST OF TABLES xiv
LIST OF FIGURES xv
LST OF SYMBOLS xvii
LIST OF ABBREVIATIONS xix
LIST OF APPENDIX xx
CHAPTER I INTRODUCTION 1
1.1 Background 1
1.2 Problem Statement 2
1.3 Objectives 3
1.4 Scope of Study 3
CHAPTER II LITERATURE REVIEW 5
2.1 District Cooling System (DCS) 5
CHAPTER TITLE PAGE
2.1.2 The District Cooling System (DCS) Concept
7
2.1.3 The Benefits of DCS 8
2.2 Thermal Energy Storage (TES) 9
2.2.1 Overview of TES 9
2.2.2 Economics of Thermal Storage 10
2.2.3 Other Benefits 12
2.2.4 Storage System Technologies 14 2.2.4.1 Chilled Water Storage 14
2.2.4.2 Ice storage 17
2.2.4.3 Eutectic Salts Storage 21 2.2.5 The Variations of Mechanisms 22
2.2.5.1 Chilled Water System 22
2.2.5.2 Ice Storage System 25
2.2.5.3 Eutectic Salt Systems 32 2.2.6 The Variations of Design and Operating
Strategies
33
2.2.6.1 Full Storage System 33
2.2.6.2 Partial Storage 34
CHAPTER III METHODOLOGY 36
3.1 Introduction 36
3.2 Implementation Flow Chart 37
3.3 Carmel Software 38
3.4 Loadsoft 6.0 Software 40
3.5 Data Insertion, Checks and Outputs 41
3.5.1 Terminology 41
3.5.2 Data Insertion 43
xi
CHAPTER TITLE PAGE
3.5.4 Outputs 61
3.5.4.1 Calculation Month and Time Range
62
3.5.4.2 Standard Outputs 63
3.5.4.3 What-If Scenario Outputs 64
3.5.5 Report Description 64
3.5.5.1 System/Area Heating and Cooling Load Summary Report
64
3.5.5.2 Breakdown of All Load Components Report
65
3.5.5.3 Detailed Psychrometric Analysis Report
67
3.5.5.4 Wall and Window Load Summary Report
67
3.5.5.5 Graph Outputs 68
3.6 Equipment Selection 70
3.6.1 STL Tank 70
3.6.1.1 Atmospheric Tank Option 71 3.6.1.2 Pressurized Tank design Option 72
3.6.2 Chillers 73
3.6.2.1 Types of Chillers 74
3.6.3 Cooling Tower 77
3.6.3.1 Type of Cooling Tower 77
3.6.3.2 Water Treatment 79
3.6.4 Heat Exchanger 80
3.6.4.1 Types of Heat Exchanger 80
3.6.5 Air Handling Unit (AHU) 82
3.6.5.1 Temperature Control 84
CHAPTER TITLE PAGE
CHAPTER IV RESULT 85
4.1 Introduction 85
4.2 DCS Incorporating With TES Technology 86 4.3 Results/Outputs of Carmel Software 86 4.3.1 System/Area Heating and Cooling
Load Summary Report
87
4.3.2 Breakdown of All Load Components Report
89
4.3.3 Detailed Psychrometric Analysis Report
91
4.3.4 Wall and Window Load Summary Report
92
4.3.5 Graph Output 93
4.4 Result Analysis 95
CHAPTER V DISCUSSION 96
5.1 Introduction 96
5.2 Equipment Selection 97
5.2.1 Encapsulated Ice 97
5.2.1.1 Benefits of Using Ice Balls 99 5.2.1.2 Basic System Operation 100 5.2.1.3 Modular Tanks vs. Encapsulated
Ice Storage
101
5.2.2 STL Tank 104
5.2.2.1 Inventory Tank 104
5.2.2.2 STL Tank Size Determination 105
5.2.3 Chiller 107
5.2.3.1 Centrifugal Chiller 108
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CHAPTER TITLE PAGE
5.2.5 Heat Exchanger 110
CHAPTER IV CONCLUSION AND SUGGESTION 112
6.1 Conclusion 112
6.2 Suggestion 112
REFERENCES 114
BIBLIOGRAPHY 116
APPENDIX A 118
APPENDIX B 120
LIST OF TABLE
TABLE TITLE PAGE
2.1 Comparison of alternative thermal storage technologies 14
4.1 Benefits of using ice balls 99
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LIST OF FIGURES
FIGURE TITLE PAGE
2.1 Typical DCS configuration 7
2.2 Typical design day chilled water load profile 11
2.3 How TES technology saves energy cost 13
2.4 Chilled water storage tank with siphon baffles 16 2.5 Ice shedder thermal storage system schematic 18 2.6 External melt coil freezing thermal storage system
schematic
19
2.7 Internal melt coil freezing thermal storage system schematic
20
2.8 Chilled water stratification 24
2.9 Typical chilled water configuration 24
2.10 Typical ice-harvesting configuration 26
2.11 External-melt ice-on-coil 27
2.12 Internal melt ice-on-coil 27
2.13 Direct refrigerant external-melt ice-on-coil configuration
28
2.14 Secondary coolant external-melt ice-on-coil configuration
28
2.15 Typical internal-melt ice-on-coil configuration 29
2.16 Typical Ice Slurry Configuration 30
2.17 Encapsulated ice balls 31
2.18 Typical encapsulated ice configuration 31
2.19 Eutectic salt container 32
FIGURE TITLE PAGE
2.21 Full storage 33
2.22 Partial storage – load leveling 34
2.23 Partial storage – demand limiting 35
3.1 Implementation flow chart 37
3.2 Software program from Carmel 39
3.3 Basic data input 44
3.4 System inputs 45
3.5 Air volume calculation type / pretreating 47
3.6 Zone inputs 48
3.7 General area 49
3.8 Wall and roof envelope 50
3.9 Wall CTS number 51
3.10 Roof CTS number 52
3.11 Window envelope 53
3.12 Window SHGC properties 53
3.13 Window construction U-value 54
3.14 Door envelope 55
3.15 Internal / other 56
3.16 People activity level 56
3.17 Schedule 58
3.18 Appliance list 59
3.19 Checks/outputs 61
3.20 Display Report 1 63
3.21 Display Report 2 63
3.22 Graphing output option 69
3.23 Atmospheric Tank System 72
3.24 Pressurized tank system 73
3.25 Centrifugal chiller 75
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FIGURE TITLE PAGE
3.27 Screw chiller 76
3.28 Cross flow cooling tower 78
3.29 Cross flow cooling tower system 78
3.30 Counter flow cooling tower 79
3.31 Counter flow cooling tower system 79
3.32 Shell and tube heat exchanger 81
3.33 Plate heat exchanger 82
3.34 Plate fin heat exchanger 82
3.35 Air handling unit 83
4.1 Horizontal bar chart 93
4.2 Pie chart 94
4.3 Line chart 94
5.1 Ice ball characteristic 98
5.2 Charging and discharging process of ice ball 98
5.3 Charging cycle 100
5.4 Discharging cycle 100
5.5 Standby mode 101
5.6 Modular ice storage tanks 102
5.7 Encapsulated ice 103
5.8 Centrifugal chiller parts 108
5.9 Reduction in chiller capacity usage 110
5.10 Cooling tower crossflow type design 111
5.11 Plate heat exchanger (PHE) 113
LIST OF SYMBOLS
BTU = British Thermal Unit
C = Celsius
CFM = Cubic Feet Meter
F = Fahrenheit
hr = Hour
J = Joule
J/kg = Joule per kilogram
K = Kelvin
kg = Kilogram
KJ = Kilojoules
kPA = Kilopascal
kW = Kilowatt
kW/h = Kilowatt per Hour
kWh = Kilowatt hour
m3 = Cubic meters
m3/hr = Cubic meters per Hour
mm = Millimeter
RT = Refrigerant ton RTHr = Refrigerant ton hour SqFt = Square feet
SqM = Square meter
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LIST OF ABBREVIATION
ASHRAE = American Society of Heating, Refrigerating and Air-Conditioning Engineers
CMA = Calcium Magnesium Acetate
COP = Coefficient of Performance
CTS = Conduction Time Series
DCS = District Cooling System
DX = Direct Expansion
FKM = Fakulti Kejuruteraan Mekanikal (Faculty of Mechanical Engineering) HCFC = Hydrochlorofluorocarbons
HFC = Hydrofluorocarbon
HVAC = Heating, Ventilating and Air-Conditioning
HW = Heavy Weight
IP = Inch-Pound
L/s = Litres per second
O&M = Operation and Maintenance
PSM = Projek Sarjana Muda
RTS = Radiant Time Series
SHGC = Solar Heat Gain Coefficient
SI = System International
STL = Storage Thermal Latent
TES = Thermal Energy Storage
TNB = Tenaga Nasioanal Berhad
TNEC = TNB Engineering Corporation UTeM = Universiti Teknikal Malaysia Melaka
LIST OF APPENDIX
APPENDIX TITLE PAGE
A Gantt Chart 118
B Data Insertion in Carmel Software and Graph Output 120
1
CHAPTER I
INTRODUCTION
1.1 Background
Referred to Robert (2003), there are two types of HVAC systems designed to satisfied building cooling requirements; direct expansion (DX) systems, in which there is direct heat exchange between the building air and the refrigerant, and secondary refrigerant systems that utilize chilled water as an intermediate heat exchange medium to transfer heat from the building air to the refrigerant which we called it centralized cooling system or commercially named Direct Cooling System (DCS).
Basically, a DCS distributes thermal energy in the form of chilled water or other media from a central source to multiple buildings through a network of underground pipes for use in space and process cooling. The cooling or heat rejection is usually provided from a central cooling plant, thus eliminating the need for separate systems in individual buildings. In DCS there is one new technology which called Thermal Energy Storage (TES). This type of system has been use widely in overseas but only introduced in Malaysia for about few years.
the stored cooling energy is released by circulating chilled water through the storage system and onto the buildings. Only a limited amount of chiller capacity needs to operate during this period. By adopting this concept, the plant consumes less electricity during the day, when electricity tariff is high. This leads to significant savings in operating costs. As the electrical power demand for this plant is also low during the day, further cost saving is achieved through reduced maximum demand charges.
There are many different types of thermal storage systems representing different combinations of storage media, charging mechanisms, and discharging mechanisms. The basic media options are water, ice, and eutectic salts. This system can be further broken down into ice harvesting, ice-on-coil, ice slurry, and encapsulated ice options.
