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