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AIR CONDITIONING STUDY FOR AUTOMOTIVE APPLICATION
ALAUDDIN HAFIZ BIN YUSOF
UNIVERSITI MALAYSIA PAHANG
UNIVERSITI MALAYSIA PAHANG
BORANG PENGESAHAN STATUS TESIS
JUDUL: AIR CONDITIONING STUDY FOR AUTOMOTIVE
APPLICATION
SESI PENGAJIAN: 2008/2009
Saya ALAUDDIN HAFIZ BIN YUSOF (860529-46-5339)
mengaku membenarkan tesis (Sarjana Muda / Sarjana / Doktor Falsafah)* ini disimpan di perpustakaan
dengan syarat-syarat kegunaan seperti berikut:
1. Tesis ini adalah hakmilik Universiti Malaysia Pahang (UMP).
2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja.
3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi
pengajian tinggi.
4. **Sila tandakan (√)
SULIT (Mengandungi maklumat yang berdarjah keselamatan atau
kepentingan Malaysia seperti yang termaktub di dalam AKTA
RAHSIA RASMI 1972)
TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh
organisasi / badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkan oleh:
_________________________ __________________________
Alamat Tetap:
LOT 9140 KG HUTAN BANAU, MOHD YUSOF BIN TAIB
BINJAI RENDAH,
21400 MARANG,
JOHOR
Tarikh: 11 NOVEMBER 2008 Tarikh: 11 NOVEMBER 2008
CATATAN: * Potong yang tidak berkenaan
** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.
Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara Penyelidikan, atau
disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM).
√
AIR CONDITIONING STUDY FOR AUTOMOTIVE APPLICATION
ALAUDDIN HAFIZ BIN YUSOF
A report submitted in partial fulfillment of the
requirements for the award of the degree of
Bachelor of Mechanical Engineering
Faculty of Mechanical Engineering
UNIVERSITI MALAYSIA PAHANG
NOVEMBER 2008
ii
SUPERVISOR’S 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: ……………..........
Supervisor: Mr. Mohd Yusof bin Taib
Position: Lecturer
Date:
Signature: ……………………..
Panel: Mr. Azizuddin bin Abd Aziz
Position: Lecturer
Date:
iii
STUDENT’S 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: Alauddin Hafiz bin Yusof
ID Number: MA 05058
Date:
iv
To My Beloved Father And Mother
Yusof bin Sulong
Zairina Nur binti Nurpantoro
v
ACKNOWLEDGEMENT
All praises and thanks be to Allah S.W.T, who had guided us to this, never
could we have found guidance, were it not that Allah had guided us! (Q7 : 43 )
I would like to express profound gratitude to my supervisor, Mr Mohd Yusof
bin Taib, for his invaluable support, encouragement, supervision and useful
suggestions throughout this research work from the beginning. His moral support and
continuous guidance enabled me to complete my work successfully.
I am also highly thankful to the assistant instructor engineer, Mr Faizul
Syahidan bin Rajuli for constantly being helping in technical aspect during the
development of the test rig process.
I am as ever, especially indebted to my parents, Mr Yusof bin Sulong and Mrs
Zairina Nur bt Nurpantoro for their love and support throughout my life. I really
appreciate for all what they have done for me and I take it as an inspiration for me to
success.
Lastly, I want to thank to all my friends who shared and giving me their ideas
and advise in completing this project. Thank you very much and may Allah bless all
of you.
vi
ABSTRACT
Air conditioning is a process by which air is cooled or heated, cleaned or filtered,
and circulated or recirculated. Air conditioning had become a standard option on
most vehicle for enhancing comfort and safety. Most of automotives air conditioning
system, the compressor is a belt-driven coupled to the engine. This means the cycling
rate is directly related to the engine speed. Based on the situation, the air
conditioning test rig was built to understand clearly about the air conditioning system
including the vapor compression refrigeration cycle in the system and the function of
each component in the system. There are four locations of temperature measurement
were selected in order to develop the test rig. These locations are at the inlet and
outlet of the compressor, the outlet of the condenser, and the inlet of the evaporator,
respectively. The pressure was measured at the low pressure side and high pressure
side which are at the outlet of the evaporator and inlet of the condenser, respectively.
All of the parameters are measured during the cycle and were analyzed by using the
properties table for refrigerant-134a and the p-h diagram for refrigerant-134a in order
to determine the heat rejection, cooling effect, work of compressor and the
coefficient of performance (COP) of the air conditioning system. The refrigerant
mass flow rate was calculated based on the theory calculation. The heat rejection,
cooling effect, work of compressor, refrigerant mass flow rate, and the COP of the
air conditioning system were investigated at variable speed of compressor. The COP
of the system was decreasing as the increasing of the compressor speed. The COP of
the system at the compressor speed of 1500 rpm is 13.48 and was decreasing to the
value of 10.33, 7.82, and 6.53 when the compressor speed was increasing to 2000
rpm, 2500 rpm, and 3000 rpm, respectively.
vii
ABSTRAK
Penyaman udara adalah satu proses di mana udara disejukan atau dipanaskan, dan
dibersihkan atau ditapiskan. Penyaman udara telah menjadi satu keperluan pada
kebanyakan kenderaan untuk meningkatkan keselesaan dan keselamatan.
Kebanyakan sistem penyaman udara automotif, pemampat adalah dipacu oleh enjin
dengan menggunakan tali sawat. Ini bermakna kadar kitaran berkadar langsung
dengan kelajuan enjin. Berdasarkan situasi ini, satu alat kelengkapan pengujian
dibina untuk pemahaman yang jelas tentang sistem penyaman udara termasuk kitaran
penyejukan wap unggul yang diguna dalam sistem penyaman udara dan fungsi setiap
komponen di dalam sistem itu. Terdapat empat tempat bagi pengukuran suhu yang
telah ditentukan untuk pembinaan alat kelengkapan pengujian ini. Tempat-tempat
pengukuran suhu ini adalah pada saluran masuk pada pemampat, saluran keluar pada
pemampat, saluran keluar pada alat kondensasi, dan saluran masuk alat pengewapan.
Tekanan dalaman sistem telah diukur pada bahagian tekanan rendah dan bahagian
tekanan tinggi yang mana masing-masing adalah di saluran keluar pada alat
pengewapan dan di saluran masuk alat kondensasi. Semua perimeter telah diukur
sepanjang kitaran pada dan telah dianalisis dengan menggunakan jadual harta untuk
bahan pendingin R-134a dan carta p-h untuk bahan pendingin R-134a dalam
menentukan jumlah penyingkiran haba, kesan penyejukan, kerja yang dilakukan oleh
pemampat dan pekali prestasi sistem (COP). Kadar aliran jisim bahan pendingin
dikira berdasarkan teori pengiraan. Penyingkiran haba, kesan penyejukan, kerja yang
dilakukan oleh pemampat, kadar aliran jisim bahan pendingin, dan COP sistem telah
diselidik pada kelajuan pemampat yang berbeza. COP sistem telah menurun selari
dengan peningkatan kelajuan pemampat. COP sistem apabila pemampat berkelajuan
1500 rpm ialah 13.48 dan telah menurun kepada 10.33, 7.82, dan 6.53, masing-
masing apabila pemampat berkelajuan 2000 rpm, 2500 rpm, dan 3000 rpm.
viii
TABLE OF CONTENTS
Page
SUPERVISOR’S DECLARATION ii
STUDENT’S DECLARATION iii
ACKNOWLEDGEMENTS iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF SYMBOL xiii
LIST OF ABBREVIATIONS xiv
CHAPTER 1 INTRODUCTION
1.1 Automotive Air Conditioning System 1
1.2 Project Problem Statement 4
1.3 Project Objectives 4
1.4 Project Scopes 4
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 5
2.2 Theory of Air Conditioning System 6
2.3 Components of Air Conditioning System 9
2.3.1 Compressor 9
2.3.2 Condenser 10
2.3.3 Receiver Drier 11
2.3.4 Expansion Devise/Metering Devise 12
2.3.5 Evaporator 13
ix
2.4 Automotive Air Conditioning Test Rig Review 14
2.4.1 Temperature Measurement 14
2.4.2 Pressure Measurement 16
2.5 Summary 17
CHAPTER 3 METHODOLOGY
3.1 Introduction 18
3.2 Methodology Flowchart 19
3.3 Development of Test Rig 20
3.3.1 Pressure Measurement 21
3.3.2 Temperature Measurement 22
3.3.3 Mass Flow Rate Measurement 23
3.4 Experiment Setting Up 24
3.5 Purging 24
3.6 Evacuation 25
3.7 Charging 26
3.8 Procedure for Test Rig Testing 27
3.9 Procedure for Experimental Work by Using Actual Car 28
3.10 Summary 29
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Introduction 30
4.2 Development of Air Conditioning Test Rig 31
4.2.1 Data Collection 32
4.2.2 Data Analysis 32
4.3 Experimental Work on Actual Car 37
4.3.1 Data Collection 37
4.3.2 Data Analysis 37
4.3.3 Effect of Compressor Speed 42
4.4 Summary 46
x
CHAPTER 5 CONCLUSION AND RECOMMENDATIONS
5.1 Conclusions 47
5.2 Recommendations 49
REFERENCES 50
APPENDICES 51-62
xi
LIST OF TABLES
Table No. Page
4.1 Data Collection for The Test Rig Testing 32
4.2 Data Analysis for The Test Rig Testing 34
4.3 Data Collection for The Experimental Work on Actual Car 37
4.4 Data Analysis for The Experimental Work on Actual Car 38
xii
LIST OF FIGURES
Figure No. Page
1.1 Schematic Diagram of Automotive Air Conditioning System 1
2.1 Schematic and T-s diagram for the ideal vapor-compression
refrigeration cycle
6
2.2 A simplified ideal vapor compression refrigeration cycle operating
between temperatures Tlow and Thigh
7
2.3 Automotive Air Conditioning Compressor 9
2.4 Automotive Air Conditioning Condenser 11
2.5 Automotive Air Conditioning Receiver-Drier 12
2.6 Automotive Air Conditioning Thermostatic Expansion Valve 13
2.7 Automotive Air Conditioning Evaporator 14
2.8 Schematic Diagram for The Test Rig done by O. Kaynakli and I.
Horuz
15
2.9 Schematic Diagram for The Test Rig done by Eric. B. Ratts and J.
Steven Brown
15
2.10 Schematic Diagram for The Test Rig done by M. Hosoz and H.M.
Ertunc
17
3.1 Methodology Flow Chart 19
3.2 Schematic Diagram for the Automotive Air Conditioning
Development
21
3.3 Bourdon Pressure Gauge 22
3.4 Vacuum Pump 25
3.5 Manifold Gauge 25
xiii
3.6 Experiment Set Up
29
4.1 Air Conditioning Test Rig 31
4.2 p-h Diagram for Ideal Vapor Compression Refrigeration Cycle
System
33
4.3 p-h Diagram for Vapor Compression Refrigeration Cycle of The
Test Rig System
35
4.4 p-h Diagram for Ideal Vapor Compression Refrigeration Cycle
System
36
4.5 p-h diagram for refrigeration cycle at compressor speed is 1500
rpm
39
4.6 p-h diagram for refrigeration cycle at compressor speed is 2000
rpm
49
4.7 p-h diagram for refrigeration cycle at compressor speed is 2500
rpm
40
4.8 p-h diagram for refrigeration cycle at compressor speed is 3000
rpm
40
4.9 Location of High Pressure Pipe and Low Pressure Pipe Behind
The Condenser Fan in Car Engine Compartment
41
4.10 Graph of Heat Rejection Vs Compressor Speed 42
4.11 Graph of Cooling Effect Vs Compressor Speed 43
4.12 Graph of Refrigerant Mass Flow Rate Vs Compressor Speed 43
4.13 Graph of Compressor Work Vs Compressor Speed 44
4.14 Graph of Coefficient of Performance Vs Compressor Speed 44
xiv
LIST OF SYMBOLS
P Pressure
T Temperature
h Enthalpy
Qhigh Heat Rejection
Qlow Cooling Effect
Wc Work of Compressor
m mass
ρ Density
Vc Compressor Displacement Volume
ωc Speed of Compressor
ηc Compressor Volumetric Efficiency
R Gas Constant
�� Mass Flow Rate
��� Compressor Volumetric Rate
kg Kilogram
°C Degree Celcius
kJ Kilojoule
Pa Pascal
s Second
m Meter
xv
LIST OF ABBREVIATIONS
COP Coefficient of Performance
TXV Thermostatic Expansion Valve
FOV Fixed Orifice Tube
VCRC Vapor Compression Refrigeration Cycle
CHAPTER 1
INTRODUCTION
1.1 AUTOMOTIVE AIR CONDITIONING STUDY
Air conditioning system is defined as the simultaneous mechanical control of
temperature, humidity, and air motion [8]. Majority of automotive air conditioning is used
the vapor compression refrigeration systems in its cycle. The schematic diagram as shown in
Figure 1.1 has illustrated the operation of the automotive air conditioning system.
Figure 1.1: Schematic Diagram of Automotive Air Conditioning System
2
The major components of the automotive air conditioning system are a
compressor, an evaporator, a condenser, and an expansion valve. The compressor is
the heart of the air conditioning system. The compressor continuously cycles on and
off to meet the cooling requirements of the passenger compartment and is mounted
to the engine and is belt driven and its cycling rate is directly related to the
automobile vehicle speed. At the front of the compressor is the magnetic clutch
which when given power engages the compressor. The condenser is usually in front
of the radiator. The expansion valve controls the flow of refrigerant into the
evaporator. The expansion valve has a capillary tube with a thermal bulb that
controls how far open or closed it is. The thermal bulb and the internal pressure of
the refrigerant balance to control just the exact amount of refrigerant needed. The
thermal bulb is clamped to the output of the evaporator. If not enough refrigerant is
flowing to cool the evaporator, this bulb is sense it and open more or vice versa. The
evaporator is the heat exchanger that removes heat from the inside of the vehicle. It
is located in or adjacent to the passenger compartment, usually mounted on the fire
wall. As the refrigerant-134a passes through the evaporator, heat transfer from the air
flowing across results in the vaporization of the refrigerant. Vapor refrigerant leaving
the evaporator is compressed to a relatively high pressure and temperature by the
compressor. Next, the refrigerant passes through the condenser, where the refrigerant
condenses and there is heat transfer from the refrigerant to the air flow across the
condenser. Finally, the refrigerant enters the expansion valve and expands to the
evaporator pressure. The refrigerant exits the valve as a two-phase liquid-vapor
mixture and gets in to the evaporator to begin the cycle again. The airflow across the
evaporator is either re-circulated air from the passenger compartment or fresh air
drawn from the outside, or some combination of the two.
The refrigerant system reaches to a steady-state operating condition when the
mass flow rate through the compressor is equal to the amount of vapor generated in
the evaporator [4]. The automotive air conditioning system is designed to operate
under a wide range of heat conditions, and as such the capacity of the fixed volume
compressor is larger than needed under most operating conditions. To allow the
system to function across a wide range of environmental conditions, the compressor
is cycled on and off based on the low-side refrigerant pressure. The compressor is
shut off when the pressure in the evaporator falls below the preset value which is
3
chosen to assure that condensate does not freeze on the evaporator. Even after the
compressor shuts off, there will still persist a pressure imbalance across the
expansion valve that will force refrigerant to flow from condenser to the evaporator.
As the evaporator fills with the refrigerant, its pressure will increase. Once the low
side refrigerant pressure reaches the preset level, the compressor will restart. The
compressor is continuously turned on and off in this manner. Since the compressor is
belt driven device coupled to the engine, when the engine speed changes so does the
compressor speed, which results in a fluctuation of the refrigerant mass flow rate.
Turning the compressor on and off position is provided by an electro-magnetic
clutch.
There are several different types of automotive air conditioning systems which
are the Receiver Drier (Filter Drier) – Expansion Valve System which uses the valve
to control refrigerant flow and cycles the compressor clutch to control evaporator
temperature and the Accumulator – Orifice Tube System which uses a fixed orifice
and an accumulator to control refrigerant flow and cycles the compressor clutch to
control evaporator temperature, and Suction Throttling Valve System which uses an
expansion valve to control refrigerant flow into the evaporator and a suction
throttling valve to control refrigerant flow out of the evaporator. The last system
does not cycles the compressor clutch, rather it cycles the compressor suction to the
evaporator.
4
1.2 PROBLEM STATEMENT
Most of people were said that the performance of the air conditioning system
was measured by the level of cooling the air that was produced by the air
conditioning system. It means that if the air produced by the air conditioning system
is cool, the performance of the air conditioning system was still good. Cooler the air
produced by the air conditioning system means the performance is better. Is it the
true statement? How about the performance of the system if it is measured based on
the theory of air conditioning? Actually, the performance of air conditioning system
still unknown except several parameters which is pressure and temperature of the
refrigerant were measured.
1.3 PROJECT OBJECTIVES
a. To develop air conditioning test rig for automotive application in order to
analysis the performance of the air conditioning system.
b. To analyze the relation of the performance of air conditioning system at variable
speed of compressor.
1.4 PROJECT SCOPES
a. Find and gather the literature review based on the previous journals and reference
books.
b. Design and develop the experimental rig.
c. Test the experimental rig.
d. Analyze the performance of the air conditioning system.
e. Documentation.
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
This chapter will be discussed about the literature review of air conditioning
system. The literature review was focused on the theory of air conditioning system
and the function of each component of the air conditioning system. In this chapter,
the development of the air conditioning test rig also had been discussed in detail and
was focused on the location of the pressure and temperature measurement. The
reference books related in the air conditioning system and the journals from previous
experiment that had been done from other people were made as references in the
development on the air conditioning test rig.
6
2.2 THEORY OF AIR CONDITIONING SYSTEM
As had been mentioned in the previous section, most of the automotive air
conditioning system is using the vapor compression refrigeration cycle. The ideal
vapor-compression refrigeration cycle is the result of eliminating the impracticalities
associated with the reversed Carnot cycle by vaporizing the refrigerant completely
before it is compressed and by replacing the turbine with a throttling device [1]. It
consists of a compressor, a condenser, an expansion device for throttling, and an
evaporator. The cycle operates at two pressures, Phigh and Plow , and consists of four
thermodynamic processes involving the working fluid, traversing four fluid states at
Tlow and Thigh [2]. The compressor delivery head, discharge line, condenser, and
liquid line form the high pressure side of the system. The expansion line, evaporator,
suction line, and compressor suction head form the low pressure side of the system.
Figure 2.1 Schematic and T-s diagram for the ideal vapor-compression refrigeration
cycle [1]
7
The ideal vapor-compression refrigeration cycle is illustrated schematically on
T-s diagram in Fig. 1. It consists of four processes [1]:
1-2 Isentropic compression in a compressor
2-3 Constant-pressure heat rejection in a condenser
3-4 Throttling in an expansion device
4-1 Constant pressure heat absorption in an evaporator
The cycle also can be illustrated on p-h diagram as shown in Figure 2.2 that
had been successfully discussed by S. Figueroa-Gerstenmaier, M. Francova, M.
Kowalski, M. Lisal, I. Nezbeda, and W.R. Smith [2]. The P-h diagram is widely used
for analyzing the performance of the cycle.
(a) (b)
Figure 2.2: A simplified ideal vapor compression refrigeration cycle operating
between temperatures Tlow and Thigh.
Figure 2.2 (a) show the process path on p–h diagram corresponding to the
schematic diagram of the process equipment as illustrated in Figure 2.2 (b) where p
is the pressure and h is the molar enthalpy. The isotherms are indicated by dashed
lines. The processes involved are as follows, with the numbers denoting the states
indicated in Figure 2.2:
1. An equilibrium liquid–vapor mixture at point 4 that is at Tlow and the
corresponding vapor pressure Plow, (P1=P4) evaporates to a saturated vapor at point 1.
The process is indicated by the line (4→1) in Figure 2.2 (a). This provides a means