air flow and temperature distribution analysis in …eprints.utem.edu.my/16569/1/air flow and...

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AIR FLOW AND TEMPERATURE DISTRIBUTION ANALYSIS IN AN AIR

CONDITIONED CAR

KHOR MEI YIN

B041110056

BMCT

Email: [email protected]

Draft Final Report

Projek Sarjana Muda II

Supervisor: DR. TEE BOON TUAN

Faculty of Mechanical Engineering

Universiti Teknikal Malaysia Melaka

JUNE 2015

mailto:[email protected]

ii

SUPERVISOR DECLARATION

“I hereby declare that I have read this thesis and in my opinion this report is

sufficient in terms of scope and quality for the award of the degree of

Bachelor of Mechanical Engineering (Thermal-Fluids)”

Signature : ……………………………

Supervisor : ……………………………

Date : ……………………………

iii

AIR FLOW AND TEMPERATURE DISTRIBUTION ANALYSIS IN

AN AIR CONDITIONED CAR

KHOR MEI YIN

This Technical Report is submitted to

Fakulti Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka

In partial fulfilment for

Bachelor of Mechanical Engineering (Thermal-Fluids) with honours

Fakulti Kejuruteraan Mekanikal

Universiti Teknikal Malaysia Melaka

JUNE 2015

iv

DECLARATION

“I hereby declare that the work in this report is my own except for summaries

and quotations which have been duly acknowledged.”

Signature : …………………….

Author : KHOR MEI YIN

Date : …………………….

v

For my beloved family and friends

vi

ACKNOWLEDGEMENT

First of all, I would like to express my gratitude to my supervisor, Dr. Tee

Boon Tuan, who has helped me so much by constantly imparting his knowledge and

ideas so that I could complete this project successfully. Sincere thanks to Dr.

Yusmady Mohamed Arifin for evaluating my final year project. The ideas and

suggestions given were valuable for me to complete this project.

Besides that, I would also like to thank Faculty of Mechanical Engineering

(FKM), Universiti Teknikal Malaysia Melaka (UTeM) for giving me this opportunity

to complete this project and allowing me to utilize all the necessary equipment and

tools needed for this study.

Finally, I would like to acknowledge with much appreciations to my family

and friends for their continuous support and encouragement throughout the project

period.

vii

ABSTRACT

Temperature and velocity are the environmental factors that affect the human

comfort level. The purpose of this study is to determine the temperature and velocity

distribution inside the passenger compartment of an air-conditioned vehicle.

Computational Fluid Dynamics (CFD) simulation is carried out by using ANSYS

FLUENT software. The measurements of air velocity and temperature are taken at

different location of the passenger seat. The difference in distribution of air flow and

temperature with and without human load inside the passenger compartment are

being investigated. The results obtained from physical measurement and CFD

simulation is analyzed and compared. The actual average temperature increases with

number of occupants while the simulation temperature remains constant, where the

largest percentage of error is 19.1 %. The simulation velocity shows highest reading

at head level and decreases as flows to chest level and knee level of passengers seats.

The trend of actual velocity is similar to simulation velocity, except at driver seat

where the highest value is at chest level. Based on the result, recommendations and

suggestions are made to improve the thermal comfort level inside the passenger

compartment.

viii

ABSTRAK

Kadar keselesaan manusia boleh berubah disebabkan oleh faktor-faktor alam

sekitar seperti suhu dan aliran udara. Kajian ini dijalankan untuk menentukan taburan

suhu dan halaju dalam kenderaan berhawa dingin melalui kaedah eksperimen dan

simulasi. Simulasi Pengkomputeran Dinamik Bendalir (CFD) akan dijalankan

dengan menggunakan perisian ANSYS FLUENT. Pengukuran halaju dan suhu udara

akan diambil pada lokasi tertentu tempat duduk kereta. Perbezaan dalam taburan

suhu dan aliran udara di dalam kereta terhadap perubahan bilangan penumpang turut

dikaji. Keputusan yang diperolehi daripada pengukuran fizikal dan simulasi CFD

dianalisis dan dibandingkan. Purata suhu eksperimen meningkat dengan penambahan

penumpang di dalam kenderaan manakala suhu simulasi adalah malar, di mana

peratusan kesilapan terbesar adalah 19.1 %. Halaju simulasi menunjukkan bacaan

tertinggi di paras kepala dan semakin turun apabila mengalir ke paras dada dan paras

lutut penumpang. Trend halaju eksperimen adalah sama dengan halaju simulasi,

kecuali di tempat duduk pemandu di mana nilai tertinggi adalah pada tahap dada.

Berdasarkan keputusan yang diperolehi, penambahbaikan dicadangkan untuk

meningkatkan tahap keselesaan penumpang dalam kenderaan berhawa dingin.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

SUPERVISOR DECLARATION ii

DECLARATION iv

ACKNOWLEDGEMENT vi

ABSTRACT vii

ABSTRAK viii

TABLE OF CONTENTS ix

LIST OF TABLES xiii

LIST OF FIGURES xv

LIST OF SYMBOLS xviii

LIST OF APPENDICES xix

LIST OF ABBREVIATIONS xx

CHAPTER 1 INTRODUCTION

1.1 OVERVIEW 1

1.2 PROBLEM STATEMENT 1

1.3 OBJECTIVES 2

1.4 SCOPES 2

1.5 EXPECTED OUTCOMES 2

CHAPTER 2 THEORY

2.1 OVERVIEW 3

2.2 ENVIRONMENTAL PARAMETERS OF

VEHICLE 3

2.3 THERMAL COMFORT 4

2.3.1 Environmental Factors 5

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CHAPTER TITLE PAGE

2.3.2 Personal Factors 5

2.3.3 Predicted Mean Vote (PMV) 6

2.3.4 Predicted Percentage Dissatisfied (PPD) 6

2.4 HEATING, VENTILATION AND AIR

CONDITIONING (HVAC) SYSTEM IN

VEHICLES 7

2.4.1 Air Flow Operation 7

2.4.2 Air Conditioning Operation 8

2.5 COMPUTATIONAL FUID DYNAMICS (CFD) 9

2.5.1 Geometry Modelling 10

2.5.2 Mesh Generation 10

2.5.3 Solver Method 11

2.5.4 Display Of Results 12

2.6 TURBULENCE MODELLING 13

CHAPTER 3 LITERATURE REVIEW

3.1 OVERVIEW 15

3.2 CFD ANALYSIS OF AIR FLOW AND

TEMPERATURE DISTRIBUTION IN AN AIR

CONDITIONED CAR BY

RAMESHKUMAR et al. (2013) 15

3.2.1 Methodology 16

3.2.2 Results And Discussion 17

3.2.3 Conclusion 19

3.3 NUMERICAL ANALYSIS OF AIR FLOW AND

TEMPERATURE FIELD IN A PASSENGER

CAR COMPARTMENT BY

HASLINDA et al. (2011) 20



3.3.3 Conclusion 22

xi

CHAPTER TITLE PAGE

3.4 STUDIES OF THE THERMAL COMFORT

INSIDE OF THE PASSENGER COMPARTMENT

USING THE NUMERICAL SIMULATION BY

IVANESCU et al. (2010) 23



3.4.3 Conclusion 27

3.5 NUMERICAL SIMULATION OF AIR

CONDITIONING VEHICLE USING

COMPUTATIONAL FLUID DYNAMICS BY

WANG AND XIANG (2009) 28



3.5.3 Conclusion 31

3.6 COMPUTATIONAL ANALYSIS OF THERMAL

DISTRIBUTION WITHIN PASSENGER CAR

CABIN BY ZEYA AND JOMON (2013) 32



3.6.3 Conclusion 34

3.7 COMPARISON OF PREVIOUS STUDIES 34

CHAPTER 4 METHODOLOGY

4.1 OVERVIEW 35

4.2 EXPERIMENTAL METHOD 35

4.2.1 Experimental Procedures 38

4.3 NUMERICAL METHOD 39

4.3.1 Geometry Process 40

4.3.2 Meshing Process 41

4.3.3 Setup Process 42

4.3.4 Solution Process 44

4.3.5 Post Processing 45

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CHAPTER TITLE PAGE

4.4 THERMAL COMFORT ANALYSIS METHOD 45

4.4.1 Thermal Comfort Analysis Procedures 46

CHAPTER 5 RESULTS AND DISCUSSION

5.1 OVERVIEW 47

5.2 EXPERIMENTAL RESULTS 47

5.3 SIMULATION RESULTS 51

5.4 COMPARISON OF EXPERIMENTAL

RESULTS AND SIMULATION RESULTS 50

5.4.1 Comparison of Temperature Distribution

Inside Passenger Compartment With

Various Human Loads 50

5.4.2 Percentage Of Error 52

5.5 GRAPHIC SIMULATIONS 53

5.5.1 Simulations of Temperature Distribution 54

5.5.2 Simulations of Air Velocity Distribution 56

5.6 THERMAL COMFORT ANALYSIS 58

CHAPTER 6 CONCLUSION AND RECOMMENDATIONS

6.1 CONCLUSION 61

6.2 RECOMMENDATIONS 62

REFERENCES 63

APPENDIX A: Flow Chart 67

APPENDIX B: Gantt Chart 68

APPENDIX C: Actual Flow of Temperature 69

APPENDIX D: Actual Flow of Air Velocity 69

APPENDIX E: Simulation Flow of Temperature 70

APPENDIX F: Simulation Flow of Air Velocity 70

xiii

CHAPTER TITLE PAGE

APPENDIX G: Percentage of Error for Temperature Distribution 71

APPENDIX H: Percentage of Error for Air Velocity Distribution 71

APPENDIX I: Thermal Comfort Analysis Evaluation Report at Driver Seat 72

APPENDIX J: Thermal Comfort Analysis Evaluation Report at Passenger Seat at Front Region 73

APPENDIX K: Thermal Comfort Analysis Evaluation Report at Right Side of Rear Passenger Seat 74

APPENDIX L: Thermal Comfort Analysis Evaluation Report at Left Side of Rear Passenger Seat 75

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LIST OF TABLES

NO. TITLE PAGE

2.1 Predicted Mean Vote Scale (ISO 7730) 5

2.2 Difference between Experimental Methods and CFD simulation

(Dmitri, 2007) 9

3.1 Computed Values of Air Velocity for Various Human Loads

(Rameshkumar et.al, 2013) 17

3.2 Computed Values of Temperature for Various Human Loads


3.3 General Boundary Conditions (Ivanescu et.al, 2010) 25

3.4 External Boundary Conditions (Ivanescu et.al, 2010) 25

3.5 Air Conditioning Unit Characteristics (Ivanescu et.al, 2010) 25

3.6 Experimental Results and Simulation Results for Air Velocity

(Ivanescu et.al, 2010) 25

3.7 Experimental Results and Simulation Results for Temperature

(Ivanescu et.al, 2010) 26

3.8 Thermal Comfort Indices with Knob of Air Flow Range Inlet on

Position 2 (Ivanescu et.al, 2010) 27

3.9 Comparison of Previous Studies 34

4.1 Location of Measuring Point 38

4.2 Turbulence Model Setup 42

4.3 Material Properties 43

4.4 Boundary Conditions Setup 43

4.5 Solution Method 44

xv

LIST OF FIGURES

NO. TITLE PAGE

2.1 Air Flow Sensation Curve (Musat and Helerea, 2009) 3

2.2 Graph of PPD against PMV (ISO 7730) 6

2.3 Mechanical electronic switches (Zhou, 2013) 7

2.4 Automatic Control of Automobile Air Conditioning

(Janotkova and Pavelek, n.d.) 8

2.5 Overview of ANSYS Workbench (Delfel, 2013) 10

2.6 Mesh Generation Process 11

3.1 Location of Measuring Points inside the Cabin


3.2 Air Velocity Distribution for Human Load of 4


3.3 Temperature Distribution for Human Load of 4


3.4 Comparison of Velocity Distribution for Various Human Loads


3.5 Comparison of Temperature Distribution for Various Human

Loads (Rameshkumar et.al, 2013) 19

3.6 Temperature Distribution for No Glazing Windscreen

(Mohamed Kamar et al., 2011) 21

3.7 Temperature Distribution for CIL Glazing Windscreen


3.8 Temperature Distribution for GIL Glazing Windscreen


3.9 Air Velocity Distribution (Mohamed Kamar et al., 2011) 22

3.10 The Measuring Points for Velocity (Ivanescu et.al, 2010) 24

xvi

NO. TITLE PAGE

3.11 The Measuring Points for Temperature (Ivanescu et.al, 2010) 24

3.12 Temperature and Velocity Distribution for Knob of Air Flow Range

Setting in Position 2 (Ivanescu et.al, 2010) 26

3.13 Graph of Thermal Comfort Indices against Time with Knob on

Air Flow Inlet in Position 2 (Ivanescu et.al, 2010) 27

3.14 Velocity Distribution at Section x=6.86 m

(Wang and Xiang, 2009) 29

3.15 Velocity Distribution at Section x=9.14 m


3.16 Temperature Distribution at Section x=6.86 m


3.17 Temperature Distribution at Section x=9.14 m


3.18 Comparison of Experimental and Simulation Temperature on

section x=6.86 m (Wang and Xiang, 2009) 31

3.19 Temperature Distribution (Ahmad Quadri and Jose, 2013) 33

3.20 Temperature Distribution with Air Inlets and Outlets

(Ahmad Quadri and Jose, 2013) 33

4.1 Toyota Corolla E110 36

4.2 Interior Arrangement 36

4.3 Dashboard 36

4.4 HVAC System Switches 37

4.5 Anemometer 37

4.6 Location of Measuring Points 37

4.7 Physical Measurement at Head Level of Passenger Seat 39

4.8 CFD Simulation Outline 40

4.9 Dimensions of Toyota Corolla E110 41

4.10 3D Car Cabin Model 41

4.11 Tetrahedrons Method Assembly Meshing 41

4.12 Thermal Microclimate HD32.1 46

4.13 Physical measurement at driver seat 47

5.1 Graph of Average Temperature against various Human Loads 51

xvii

NO. TITLE PAGE

5.2 Graph of Average Air Velocity against various Human Loads 51

5.3 Graph of Percentage of Error for Temperature Distribution 52

5.4 Graph of Percentage of Error for Air Velocity Distribution 53

5.5 Temperature Contour with no Human Load inside Passenger

Compartment 54

5.6 Temperature Contour with 1 Human Load inside Passenger

Compartment 55

5.7 Temperature Contour with 2 Human Loads inside Passenger

Compartment 55


Compartment 55


Compartment 56

5.10 Velocity Vector with No Human Load inside Passenger

Compartment 56

5.11 Velocity Vector with 1 Human Load inside Passenger

Compartment 57

5.12 Velocity Vector with 2 Human Loads inside Passenger

Compartment 57


Compartment 57


Compartment 58

5.15 Graph of PPD against PMV for Driver Seat 59

5.16 Graph of PPD against PMV for Passenger Seat at Front Region 59

5.17 Graph of PPD against PMV for Passenger Seat at Right Side of

Rear Region 59

5.18 Graph of PPD against PMV for Passenger Seat at Left Side of

Rear Region 60

xviii

LIST OF SYMBOLS

° = degree

°C = degree Celcius

% = percentage

atm = atmosphere

clo = clothing insulation

σε = turbulent Prandtl numbers for ε

σk turbulent Prandtl numbers for k

𝜀 = turbulent dissipation

Gb = turbulence kinetic energy due to buoyancy

Gk = turbulence kinetic energy due to the mean velocity gradients

k = turbulent kinetic energy

K = Kelvin

kg = kilogram

m = meter

Pa = Pascal

s = second

T = temperature, °C

V = air velocity, m/s

W = watt

YM = fluctuating dilatation in compressible turbulence to the overall

dissipation rate

xix

LIST OF APPENDICES

NO. TITLE PAGE

A Flow Chart 67

B Gantt Chart 68

C Actual Flow of Temperature 69

D Actual Flow of Air Velocity 69

E Simulation Flow of Temperature 70

F Simulation Flow of Air Velocity 70

G Percentage of Error for Temperature Distribution 71

H Percentage of Error for Air Velocity Distribution 71

I Thermal Comfort Analysis Evaluation Report at Driver Seat 72

J Thermal Comfort Analysis Evaluation Report at Passenger Seat at Front Region 73

K Thermal Comfort Analysis Evaluation Report at Right Side of Rear Passenger Seat 74

L Thermal Comfort Analysis Evaluation Report at Left Side of Rear Passenger Seat 75

xx

LIST OF ABBREVIATIONS

3D = three dimensional

ASHRAE = American Society of Heating, Refrigeration and

Air- Conditioning Engineers

ASM = algebraic stress model

CAD = Computer Aided Design

CFD = Computational Fluid Dynamics

CIL = clear insulated laminate tint

DTS = Dynamic Thermal Sensation

eqn = equation

GIL = green insulated laminate tint

HVAC = Heating, Ventilation and Air Conditioning

IAQ = Indoor Air Quality

PMV = Predicted Mean Vote

PPD = Predicted Percentage of Dissatisfied

RANS = Reynolds Averaged Navier-Stokes

RNG = Re-Normalisation Group

TS = Thermal Sensation

1

CHAPTER 1

INTRODUCTION

1.1 OVERVIEW

Thermal comfort of vehicle passengers has been emphasized due to the

increasing in time of people spends inside the vehicles. The passenger compartment

is the place which shows significant effect on thermal comfort. It is exposed to

internal disturbances such as the speed of vehicle, the number of passengers inside

the car cabin and the temperature of engine, and also external disturbances such as

air temperature, velocity of wind and solar radiation. (Mezrhab & Bouzidi, 2006) A

great temperature control inside the vehicles will provide driver a good physical state

of driving and a great visibility by avoiding fogging inside the vehicles. (Alahmer et

al., 2010) In order to improve the thermal comfort inside a vehicle, an acceptable

range of distribution of air velocity and temperature are to be considered. This

project will focus on analyzing the distribution of temperature and velocity inside the

vehicle compartment.

1.2 PROBLEM STATEMENT

Air flow and temperature distribution in an air conditioned car will change

according to the various human loads. Based on the proposed simulation, this project

is aimed to investigate the velocity and temperature distribution inside an air

conditioned car which relate to human comfort level. Measuring points of air

velocity and temperature can be taken at different location of the passenger seat by

physical measurements and Computational Fluid Dynamics (CFD) simulation. CFD

2

simulation can predict the airflow numerically without creating a prototype, thus

save cost, time and manpower. Hence, an optimum environment should be able to

simulate by using CFD software in analyzing the temperature and air flow inside

passenger compartment, in order to improve the thermal comfort level. Thermal

comfort of passengers inside vehicle can be evaluated by Predicted Mean Vote

(PMV) and Predicted Percentage of Dissatisfied (PPD).

1.3 OBJECTIVES

i. To investigate the temperature and air flow distribution with and without

human loads inside the passenger compartment.

ii. To perform thermal comfort analysis inside vehicle.

1.4 SCOPES

i. Evaluate the air flow and temperature distribution by experimental method

(measurement) and CFD simulation.

ii. Only indoor environmental condition of the car is taken into consideration.

iii. Boundary parameters are determined for valid CFD modelling to be applied

in the car.

1.5 EXPECTED OUTCOMES

i. Physical measurement of distribution of temperature and air velocity in an air

conditioned vehicle.

ii. CFD simulation of distribution of temperature and air velocity in an air

conditioned vehicle.

iii. Compare results between physical measurement and numerical simulation.

iv. Thermal comfort analysis inside the air conditioned vehicle.

v. Recommendations to improve the thermal comfort level inside the passenger

compartments.

3

CHAPTER 2

THEORY

2.1 OVERVIEW

All the principles and definitions related to the case study should be included

in this chapter. The theories such as thermal comfort, Heating, Ventilation and Air

Conditioning (HVAC) system in vehicles, CFD and turbulence modelling are studied

and compiled in this chapter for better understanding.

2.2 ENVIRONMENTAL PARAMETERS OF VEHICLE

A vehicle is exposed to both internal disturbances such as car speed, engine

temperature and passengers inside car cabin, and also external disturbances such as

temperature, sun and wind. This project will focus on environmental parameters that

are temperature and air velocity distribution inside the air conditioning car. Figure

2.1 shows the relationship between air velocity and temperature. The air velocity will

increase with temperature.

Figure 2.1: Air Flow Sensation Curve (Musat and Helerea, 2009)

4

When the air conditioning system is switched on, the temperature will drop

slightly as the cooled air is suddenly directed into the passenger compartment and

will rise steadily as time passed. Due to the small space inside passenger

compartment, the temperature will be affected by the heat exchange in the space

(Zhou, 2013). When there are occupants inside the vehicle cabin, the temperature

will increase due to the sensible heat transferred from human body. (Mohamed

Kamar et. al., 2013)

The air flow inside the vehicle is directed to a small section due to the limited

space of car. The air flows from air conditioning vents will increase the air velocity.

It will be blocked by the front seats and rear seats and formed recirculating flow

patterns. This flow pattern is well mixed with the cold air from air conditioning inlets

and the surrounding heated air inside vehicle cabin, and then directed back to the air

conditioning outlets (Jalal and Haider, 2007). Hence, the air velocity will decrease as

human loads will occupy certain spaces inside the passenger compartment.

2.3 THERMAL COMFORT

American Society of Heating, Refrigeration and Air-Conditioning Engineers

(ASHRAE) Standard 55 defines thermal comfort as “that condition of mind which

expresses satisfaction with the thermal environment”. However, different people

have different sensations towards the thermal environment. Hence, six factors are

used as an indicator of thermal comfort:

i. Air temperature

ii. Air velocity

iii. Radiant temperature

iv. Humidity level

v. Clothing insulation

vi. Activity level

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