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REFRIGERATION STUDY FOR DOMESTIC APPLICATION
ANIZAN BIN WAN RAMLI
A report submitted in partial fulfillment of the requirements for the award of the degree
Bachelor of Mechanical Engineering
Faculty of Mechanical Engineering
UNIVERSITI MALAYSIA PAHANG
NOVEMBER 2008
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SUPERVISORS DECLARATION
We hereby declare that we have checked this project and in our opinion this project is
satisfactory in terms of scope and quality for the award of the degree of Bachelor of
Mechanical Engineering
Signature : ..........................................
Name of Supervisor: Mohd Yusof bin Taib
Position : Lecturer
Date : ..........................................
Signature : ...........................................
Name of Panel : ...........................................
Position : ...........................................
Date : ...........................................
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STUDENTS DECLARATION
I hereby declare that the work in this thesis is my own except for quotations and
summaries which have been duly acknowledged. The thesis has not been accepted for
any degree and is not concurrently submitted for award of other degree.
Signature : .................................................
Name : Anizan bin Wan Ramli
ID Number: MA05030
Date : .................................................
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To my beloved father and mother,
Mr Wan Ramli bin Wan Abdul Rahman
Mdm Jariah binti Mohamad
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ACKNOWLEDGEMENTS
Alhamdulillah, I would like to take this opportunity to express my deepest
gratitude to Allah because of His willingness to give strength and will for me to finish
this project successfully. First and foremost, many warm thanks to my supervisor Mr
Yusof bin Taib for his constant help, support and guidance which has steered me to
finish my project. His enthusiasm and professional works has motivated me whenever I
feel down while doing my project. Whenever I really need help, he always provide me
with his help and ideas which helped me overcome the difficulties in doing my project. I
am very grateful for his willing helping me without asking for a repay
My sincere thanks go to all my friends, the staff of the Mechanical Engineering
Department, UMP, who helped me in many ways and made my stay at UMP pleasant
and unforgettable. Many special thanks go to my colleagues in M16, M17, M20, M23
and all mechanical students in UMP for their excellent co-operation, inspirations and
supports during this study.
I acknowledge my sincere indebtedness and gratitude to my parents for their
love, dream and sacrifice throughout my life. I cannot find the appropriate words that
could properly describe my appreciation for their devotion, support and faith in my
ability to attain my goals. Special thanks should be given to my committee members. I
would like to acknowledge their comments and suggestions, which was crucial for the
successful completion of this study.
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ABSTRACT
Refrigeration, cooling, and heating processes are important in a variety of everyday
situations, including the air conditioning and heating of buildings, and in a treatment,
transportation, and preservation of foods and beverages. Refrigeration also finds large
scale industrial application, for example, in the manufacture of ice and the dehydration
of gases. This paper gives an understanding of refrigeration study for domestic
application. By learning and understanding the basic vapour-compression refrigeration
systems, the performance of refrigeration system expected can be determined using
refrigerator test rig. The literature study has been conducted by two important
parameters in order to analyze performance of the refrigerator. These parameters are
pressure and temperature. The literature study is crucial at the location of parameter on
the test rig that will be develop. This paper also describes procedure to fabricate the test
rig. Then, the refrigerator test rig will test in order to analyse the performance of the
refrigerator test rig. The performance of the refrigerator test rig analyse by the using the
actual pressure-enthalpy diagram of actual refrigeration cycle and by using the equation.
This study may help the audience to analyze the actual performance of the refrigerator
performance for domestic application.
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ABSTRAK
Penyejukan, pendinginana dan pemanasan adalah proses yang penting dalam pelbagai
situasi setiap hari, termasuklah penghawa dingin dan pemanasan bangunan dan dalam
rawatan, pengangkutan dan pengekalan kualiti makanan dan minuman. Penyejukan
digunakan secara meluas dalam aplikasi perindustrian, contohnya dalam pembuatan ais
dan dehidrasi gas. Kertas kerja ini memberi pemahaman dalam kajian untuk penggunaan
domestik. Melalui pembelajaran dan pemahaman asas kemampatan wap sistem
penyejukan, kecekapan sistem penyejukan yang dijangka boleh ditentukan
menggunakan pegendali ujian peti ais. Kajian kesusasteraan telah dibimbing oleh dua
parameter penting dalam mengkaji kecekapan sesbuah peti ais. Parameter-parameter
tersebut adalah tekanan dan suhu. Kajian kesusasteraan genting di lokasi parameter pada
pengendali ujian peti ais yang akan dibuat. Kertas kerja ini juga menghuraikan prosedur
untuk membuat the pegendali ujian. Kemudian, pengendali ujian peti ais akan diuji
untuk analisis kecekapan pengendali ujian peti ais tersebut. Kecekapan pengendali ujian
peti sejuk dianalisis menggunakan gambar rajah tekanan-entalpi sebenar bagi putaran
penyejukan dan menggunakan persamaan. Kajian ini dapat membantu masyarakat untuk
analisis kecekapan sebenar bagi sesebuah peti ais untuk aplikasi domestik.
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TABLE OF CONTENTS
Page
SUPERVISORS DECLARATION ii
STUDENTS DECLARATION iii
DEDICATION iv
ACKNOWLEDGEMENTS v
ABSTRACT vi
ABSTRAK vii
TABLE OF CONTENTS viii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF SYMBOLS xiv
LIST OF ABBREVIATIONS xv
CHAPTER 1 INTRODUCTION
1.1 Introduction 1
1.3 Problem Statement 4
1.3 Objectives of the Research 7
1.4 Overview of the Thesis 8
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 10
2.2 Refrigeration System 10
2.2.1 Components of Refrigerator System 10 2.2.2 Theory of Refrigeration Cycle 11
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2.2.3 Refrigerant Effect2.2.4.....Heat Rejection In a Condenser
2.2.5.....Mass of Flow Rate
2.2.6.....Compressor Power
2.2.7.....Coefficient of Performance (COP)
14
2.3 Development Reviews of Refrigerator Test Rig 21
2.4 Measurement Method
2.4.1.....Temperature Measurement
2.4.2.....Pressure Measurement
34
CHAPTER 3 METHODOLOGY
3.1 Introduction 35
3.2 Flow Chart 36
3.2.1 Material information 39
3.2.2 Loading information 39
3.4 FE based Fatigue Analysis Process 48
3.5 FE Analysis Techniques 48
3.6 Conclusions 52
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Introduction 53
4.2 Results of Experimental Rig 53
4.2.1 Construct P-h Diagram 53
4.2.2 Enthalpy Value
4.2.3.....Refrigerant Effect Analysis
61
4.3 Validation 66
4.4 Duability Assessment 734.5 Conclusions 74
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CHAPTER 5 CONCLUSION AND RECOMMENDATIONS
5.1 Introduction 75
5.2 Conclusions 75
5.2.1 Finite element modeling 76
5.2.2 Fatigue life predictions 77
5.3 Recommendations for the Future Research 80
REFERENCES 81
APPENDICES 91
A Components of Combustion Side 91
B Components of Kickback Side 93
C List of Publications 95
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LIST OF TABLES
TABLE NO TITLE PAGE
3.1 Technical specification of the refrigerator model URF-M50A 30
4.1 Enthalpy value for each measurement point 33
4.2 Result of refrigerating effect 34
4.3 Results of heat rejection in a condenser 36
4.4 Results of Work of compressor 374.5 Results of mass flow rate 39
4.6 Results of compression power 41
4.7 Results of refrigerant capacity 43
4.8 Results of heating capacity 44
4.9 Results of Coefficient of performance (COP) 46
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LIST OF FIGURES
FIGURE NO TITLE PAGE
2.1 Refrigeration cycle shown schematically and graphically 5
2.2 Cutaway of reciprocating compressor 7
2.3(a) The process path on a pressure-enthalpy (P-h) diagram 9
2.3(b) Schematic diagram of the process equipment 9
2.4 Ideal T-s diagram of refrigerator system 10
2.5(a) Actual P-h diagram 11
2.5(b) Actual T-s diagram 11
2.6 Schematic diagram transducers line in refrigerator system 14
2.7 Schematic diagram of the test facility with the main instrumentation
points. 15
2.8 Bourdon low pressure gauge 17
3.1 Photograph URF-M50A refrigerator model 18
3.2 Flow chart of Final Year Project 19
3.3 The schematic diagram of the test unit and apparatus 21
3.4 The refrigerator test unit 21
3.5 A flare fitting and flare nut for tubing connection 22
3.6 Screw-type flaring tool 22
3.7 The fitting for soldering or brazing 24
3.8 Construction method of temperature measurement point 25
3.9 Construction temperature measurement point 26
3.10 Assembly method of pressure measurement using pressure gauge 27
4.1 Graph of refrigerating effect (kJ/kg) versus time (min) 35
4.2 Graph of heat rejection in condenser (kJ/kg) versus time (min) 36
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4.3 Graph of work of compressor (kJ/kg) versus time (min) 38
4.4 Graph of mass flow rate (kg/s) versus time (min) 40
4.5 Graph of compressor power (kJ/s) versus time (min) 41
4.6 Graph of refrigerant capacity (W) versus time (min) 43
4.7 Graph of heating capacity (kJ/s) versus time (min) 44
4.8 Graph of COP versus time (min) 45
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LIST OF SYMBOLS
Mass flow rate
Refrigeration capacity
Heating capacity
Heat rejection in a condenser
Refrigerant effect
P Pressure
V Volume
R Gas constant value
T Temperature
P Compressor power
W Work done
h Enthalpy value
Wcomp Work of compressor
V Voltage
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LIST OF ABBREVIATIONS
ANSI American National Standards Institute
ARI Air Conditioning and Refrigeration Institute
ASHRAE American Society of Heating, Refrigeration, Air Conditioning Engineers
COP Coefficient of Performance
UMP Universiti Malaysia Pahang
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CHAPTER 1
INTRODUCTION
1.1 The Domestic Refrigerator
Refrigeration is widely used in variety of thermal engineering applications.
Refrigeration is defined as the process of removal of heat from an enclosed space, or
from a substance, and rejecting it elsewhere for the primary purpose of lowering the
temperature of the enclosed space or substance and then maintaining that lower
temperature. The refrigeration system actually based on a vapor-compression cycle
which consisting four main components; a compressor, a condenser, a capillary tube or
expansion valve and an evaporator. The working fluid that used in the refrigeration
system is R-134a. The first patent of a vapor-compression refrigeration system was
obtained by American inventor named Jacob Perkins in 1834.
The cycle of vapor-compression of refrigeration start when the refrigerant enters
the compressor at high pressure of superheated vapor and its compressed isentropically
to the condenser pressure. Then, the refrigerant enters the condenser as superheated
vapor and leaves as saturated liquid as a result of heat rejecting to the surroundings. The
saturated liquid refrigerant is throttled to the evaporator pressure by passing it through
an expansion valve or capillary tube. During this process, the temperature of the
refrigerant drops below the temperature of the refrigerate space. Then, the refrigerant
enters the evaporator as a low-quality saturated mixture, and it completely evaporates by
absorbing heat from the refrigerated space. The cycle is complete as the refrigerant
leaves the evaporator and re-enters the compressor.
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This report gives an understanding of refrigeration study for domestic
application. By learning and understanding the basic vapor-compression refrigeration
systems, the performance of refrigeration system expected can be determined. The test
rig will be develop in order to analyze the performance of refrigerator. The author has
conducted literature study in identify parameter to analyze the refrigerator performance.
The literature study is crucial at the location of parameter on the test rig that will be
developed. Based on the literature study, a test rig is being developed according to the
international standard for tropical climate such as ASHRAE, AHAM and ARI to
generate the refrigerator performance.
1.2 Problem Statement
Nowadays, refrigeration system is important in a wide variety used for domestic
application. However, the actual performance of the refrigerator still unknown. So, we
need some research to analyze the actual performance of refrigerator.
1.3 Objective of Research
The main objective of this study is to develop experimental rig for refrigeration
system and to determine the coefficient of performance (COP) of the refrigeration
system.
1.4 Scope
The scopes of this study are:
1) Literature Study
The literature study is focused how to identify the strategic and suitable locations
of pressure and temperature measurement.
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2) Thermodynamics analysis
By learning and understanding the basic vapor compression refrigeration
systems, the performance of refrigeration system can be determined.
3) Test Rig development
In order to analyze performance of the refrigeration system, the test rig needs to
be developed. There are two important of parameters in the rig development
works which are location and measurement method of pressure and temperature.
4) Testing and analysis
Analyze the data by using P-h diagram and second law of thermodynamic to
determine the coefficient of performance (COP) of the system.
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CHAPTER 2
LITERATURE REVIEWS
2.1 Introduction
This chapter discusses the relevant reports on the description of refrigeration
system, components that is installed in domestic refrigerators, measurement method and
development reviews of refrigerator test rig. These reviews are important to analysis the
performance of refrigerator system in domestic application.
2.2 Refrigeration System
Currently, there are many types of refrigeration system available in the market.
Those refrigerators are classified according to their application. The most popular type
of domestic refrigeration system is called refrigerator. Normally, this type of
refrigeration system consists of two compartments which are cold and freeze
compartments. The other types of refrigerator systems are freezer and cooler. The
primary function of a refrigerator or freezer is to provide food storage space maintained
at a low temperature for the preservation of food. Mechanical vapor compression cycle
as well as the absorption cycle, are adopted for domestic refrigerators and freezer.
Refrigeration is defined id the process of removal of heat from an enclosed space, or
from substance, and rejecting it elsewhere for the primary purpose of lowering the
temperature of the enclosed space or substance and then maintaining that lower
temperature. The refrigeration system is that based on a vapor compression cycle which
consisting four main components; a compressor, a condenser, a capillary tube or
expansion valve and evaporator as shown in Figure 2.1
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Surrounding
T
Evaporator
Capillary QH 2
Tube Compressor 3
WcompWcomp
Condenser QL 4 1
s
Refrigerated
Space
(a) Refrigerator plant (b) Ideal T-s diagram of refrigeration plant
Figure 2.1: Refrigeration cycle shown schematically and graphically
2.2.1 Components of Refrigerator System
There are several mechanical components required in a refrigerator system.
Basically, there are four major components of vapor-compression refrigeration system.
These components are compressor, condenser, capillary tube and evaporator [2].
2.2.1.1 Compressor
In a refrigeration cycle, the compressor has two main functions within the
refrigeration cycle. The function of the compressor is to pump the refrigerant vapor from
the evaporator so that the desired temperature and pressure of the system. The second
function is to increase the pressure of the refrigerant vapor through the process of
compression, and simultaneously increase the temperature of refrigerant vapor [3]. The
pressure of the refrigerant vapor leaving the evaporator must be elevated (or the vapor
has to be compressed) to the level of the condensing pressure, so that the refrigerant can
be condensed into a liquid in the condenser and fed to the evaporator for the continuous
refrigeration [4].
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The most common compressor used in domestic refrigeration is reciprocating
type. This type of compressor normally constructed with pistons, cylinders, valves,
connecting rods and crankshaft as shown in Figure 2.2. The function of each main
component that commonly used in reciprocating compressor are described below:
Piston head functions as the gas compressing agent by continuously reducing
the cylinder volume
Piston rings functions as the sealant between the piston head, and the cylinder,
to prevent gas leakage from the compression chamber
Crank shaft a shaft that enables the reciprocating motion of the piston
Piston rod the connecting piece between the piston head, and the crankshaft
Spring loaded suction and discharge valves separates low pressure side and
high pressure side from the compression chamber. Enables positive displacement
of gases, by correct opening and closing of the valves. Suction valve will open as
the piston moves away from the valves, and discharge valve will open as the
piston moves towards the valves. The valves will otherwise, be in closed
position. The suction and discharge valve are usually a thin plate or reed that will
open and close easily and quickly [3].
Compressors cylinder block functions as the housing for the compressor parts
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Figure 2.2: Cutaway of reciprocating compressor
2.2.1.2 Condenser
The heat extracted from the substance to be cooled by the refrigerant in the
evaporator is rejected to the atmosphere through the condenser. There are several types
of condensers that commonly used in refrigeration system. They are air-cooled, water-
cooled, shell and tube, shell and coil, tube within a tube, and evaporative condensers [3].
However, most of domestic refrigerators are used evaporative condenser. The refrigerant
is forced through the condenser. In order to remove as much heat as possible with the
tubes arranged to provide maximize surface area. In the condenser, the temperature of
the superheated vapor has to be brought down to its saturation temperature before
condensed into a liquid. The first few tubes of the condenser desuperheat the vapor.
The pressure of the vapor, through superheated, remains the same, since the compressor
is in operation. Once the vapor has been cooled, and brought down to the condensing
temperature corresponding to the head pressure, the vapor begins to condense. During
this process, the pressure and condensing temperature remain constant. In some water-
cooled condensers, provision is made for sub-cooling the liquid from its saturation
temperature by providing some water tubes at the bottom. The liquid can be sub-cooled
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by the use of a liquid-suction heat exchanger also. The use of heat exchanger, obviously,
will increase the superheat of the suction vapor. As too much superheating of the suction
vapor will affect the compressor capacity, a heat exchanger is only used where
absolutely essential [12].
2.2.1.3 Capillary Tube
The capillary tube is the simplest type of refrigerant flow control device and may
be used in place of an expansion valve. The capillary tube is small-diameter tubes
through which the refrigerant flows into the evaporator. These devices, which are widely
used in small hermetic-type refrigeration system, reduce the condensing pressure to the
evaporating pressure in a copper tube of small internal diameter, maintaining a constant
evaporating pressure independently of the refrigeration load range. These tubes are used
to transmit pressure from the sensing bulb of some temperature control device to the
operating element. A capillary tube may also be constructed as a part of heat exchanger,
particularly in household refrigerators [5, 6].
2.2.1.4 Evaporator
Evaporator can be considered the point of heat capture in refrigeration system
and provides the cooling effect required for any particular application. In evaporator
operation, the metering device changes the entering liquid to a dense fog of liquid
droplets. During the same process, the high pressure liquid is lowered to what is called
the evaporator pressure, or suction pressure. This pressure relates to the evaporator
temperature. During evaporation, the refrigerant remains the same temperature (its
saturation temperature) throughout the coil until all droplets of liquid are vaporized, or
totally saturated.
Meanwhile, the refrigerant nears the end of evaporator part is in fully saturated
vapor that can only absorb sensible heat; however it does not contribute much to the
overall refrigeration performance.
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2.2.2 Theory of Refrigeration Cycle
Commonly, refrigeration system works in a thermodynamic cycle which obeys
Second Law of Thermodynamic which consists of four thermodynamic processes
involving the working fluid, traversing four fluid states at low temperature, T low and high
temperature, Thigh [1] and [2] as shown in Figure 2.3:
Figure 2.3: (a) Shows the process path on a pressureenthalpy (Ph) diagram, and (b)
shows a schematic diagram of the process equipment.
The cycle of refrigeration start when the refrigerant enters the compressor at low-
pressure superheated vapor and is compressed isentropically to the condenser pressure.
The refrigerant enters the condenser as superheated vapor and leaves as saturated liquid
as a result of heat rejecting to the surroundings. The saturated liquid refrigerant is
throttled to the evaporator pressure by passing it through an expansion valve or capillary
tube. During this process, the temperature of the refrigerant drops below the temperature
of the refrigerant space. Then, the refrigerant enters the evaporator as a low-quality
saturated mixture, and it completely evaporates by absorbing heat from the refrigerated
space. The cycle is complete as the refrigerant leaves the evaporator and re-enters the
compressor.