Design and analysis of fins under uncertainty heat capacity.
ｬｩｾｉ＠
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
DESIGN AND ANALYSIS OF FINS UNDER UNCERTAINTY HEAT
CAPACITY
This repott submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Design) (Hons.)
by
CHONG SEE YING
B051010010
890316-59-5344
FACULTY OF MANUFACTURING ENGINEERING
2014
© Universiti Teknikal Malaysia Melaka
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: DESIGN AND ANALYSIS OF FINS UNDER UNCERTAINTY HEAT
CAPACITY
SESI PENGAJIAN: 2013/14 Semester 2
Saya CHONG SEE YING
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti
Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Sila tandakan ( ./)
D
SULIT
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysia sebagaimana yang termaktub
dalam AKTA RAHSIA RASMI 1972)
TERHAD
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkan oleh:
ｾＭ
Alamat Tetap:
Cop Rasmi:
NO. 4, TAMAN NAGAMAS,
71650 TITI,
JELEBU, NEGERI SEMBILAN
DR. TAUFIK
Senior Lecturer
Faculty of Manufacturing Engineerfn1
. Unlverslti Teknikal Malaysia Melaall
Hang Tuah Jaya
76100 Durian Tunggal, Melab
Tarikh: 23 MAY 2014
** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
C Universiti Teknikal Malaysia Melaka
DECLARATION
I hereby, declared this report entitled "Design and Analysis of Fins under
Uncertainty Heat Capacity" is the results of my own research except as cited in
references.
Signature
Author's Name
CHONG SEE YING
Date
261h JUNE 2014
© Universiti Teknikal Malaysia Melaka
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM
as a partial fulfillment of the requirements for the degree of Bachelor of
Manufacturing Engineering (Manufacturing Design) (Hons.). The member of
the supervisory committee is as follow:
ﾷ ﾷｾＭ＠
ｾＯ＠
DR. TAUFIK
ｾｮｩｯｲ＠
Lectunr
Faculty of Manufacturing Engineerinf
Unlvenlti Teknikal Malaysia Mel.ta
Hang Tuah Jaya
76100 Durian Tunggal, Melab
© Universiti Teknikal Malaysia Melaka
ABSTRAK
Project ini terutamanya memberi pertumpuan atas reka bentuk sirip dan analisis
untuk sirip di bawah kapasitas haba yang tidak menentu. Tiga sink haba yang
bersirip dengan mempunyai geometri yang berbeza tetapi mempunyai volume yang
sama telah dipilih. Beberapa parameter yang berkaitan dengan reka bentuk sirip telah
dikenal pasti dan dipertimbangkan dengan dimensi geometri meraka. Kekangan
system seperti suhu operasi yang tertinggi pada unit pusat pemprosesan dan suhu
udara yang menyelilingi sinki haba juga telah dikenalkan sebelum simulasi
dijalankan. Aloi Aluminium 6063 yang mempunyai keberaliran haba yang dikira
cukup tinggi telah digunakan sebagai bahan untuk sinki haba yang bersirip. Lakaran
bagi model-model sirip telah dibuat untuk menjadikan reka bentuk tertentu sebagai
konsep pada peringkat awal project ini. SolidWorks 2010 yang merupakan salah
sebuah perisian CAD yang digunakan untuk menghasilkan model-model 3D bagi
reka bentuk sirip. Analisis unsur terhingga telah dijalankan dengan menggunakan
perisian ANSYS. Pada peringkat awalnya, tiga model sirip 3D, contohnya sink haba
yang bersirip plat, jalur dan splayed dianalisis di bawah keadaan yang mantap
bertujuan untuk mengaji taburan suhu dan jumlah fluks haba. Manakala, analisis
struktur static dilakukan juga untuk mendapatkan factor keselamatan bagi ketiga-tiga
sink haba bersirip. Model pemarkahan wajaran dihasilkan dengan merujuk kepada
criteria yang berkaitan. Kemudian, haba tenggelam bersirip splayed telah dipilih
sebagai reka bentuk sirip yang terbaik dan reka bentuk sirip yang lebih baik
dicadangkan berdasarkan penemuan daripada analisis keadaan mantap. Analisis fana
haba sink bersirip telah terpilih dan haba tengelam bersirip dengan tebukan telah
dijalankan masing-masing. Hasilnya, haba tenggelam bersirip berlubang telah dipilih
sebagai reka bentuk yang paling unggul dalam erti prestasi terma.
© Universiti Teknikal Malaysia Melaka
ABSTRACT
This project primarily focuses on the design and analysis of fins under uncertainty
heat capacity. Three finned heat sinks with different geometry are selected at a fixed
volume. The design parameters of fins are identified and considered with geometrical
dimensions through reviewed literature. System constraints such as maximum
operating temperature of central processing unit and air temperature surrounding the
heat sink are also defined before simulation. Aluminium alloy 6063 which has
considerably high thermal conductivity is used as the material of finned heat sink.
CAD software which is SolidWorks 2010 is used to conduct 3D modeling of the fin
designs. Finite element analysis is performed by using ANSYS software. At first, the
3D fin models which including heat sinks with plate fins, strip fins, and splayed are
analyzed under steady state condition in order to investigate their temperature
distribution and total heat flux. However, static structural analysis is performed also
to obtain the factor of safety for each fin design. Weighted scoring model is
generated by referring to the relevant criteria. In addition, the splayed finned heat
sink is chosen as the best fin design and an improved design is proposed based on the
findings from the steady state analysis. Transient thermal analysis of the selected
finned heat sink and proposed finned heat sink with perforations is conducted
respectively. As a result, the perforated finned heat sink is selected as the most
superior design in sense of thermal performance.
© Universiti Teknikal Malaysia Melaka
11
DEDICATION
To my beloved parents, siblings and friends due to their love and support.
© Universiti Teknikal Malaysia Melaka
Ill
ACKNOWLEDGEMENT
I would like to express my deep gratitude to Dr. Taufik, my supervisor for his patient
guidance, useful advice, and assistance along the progress of this project. I am
grateful for his professionalism and his tolerance to guide me.
My grateful thanks are also extended to my parents and all my family members for
their love, support and concerns.
Besides, I would also like to thank to my fellow friends who kindly provide
assistance and support to me without hesitations.
© Universiti Teknikal Malaysia Melaka
lV
TABLE OF CONTENTS
Abstrak
Abstract
11
Dedication
111
Acknowledgement
lV
Table of Contents
v
List of Tables
lX
List of Figures
x
List of Abbreviations, Symbols and Nomenclature
Xll
CHAPTER 1: INTRODUCTION
1
1.1
Background
1
1.2
Problem Statement
3
1.3
Objectives
4
1.4
Scope of Project
4
1.5
Project Organization
5
CHAPTER 2: LITERATURE REVIEW
7
2.1
Overview of Finned Heat Sink
7
2.1.1
Introduction
7
2.1.2
Categories of Heat Sinks
8
2.1.3
Types of Heat Sinks
11
2.1.4
Fin Designs
13
2.1.5
Overview of Fin Designs
16
2.2
Fin Design Principles
17
2.2.1
Introduction
17
2.2.2
System Constraints
17
2.2.2.1 Ambient Temperature
18
2.2.2.2 Maximum Operating Temperature
18
2.2.2.3 Heat Removal Capability
18
© Universiti Teknikal Malaysia Melaka
v
2.2.3
2.3
2.4
2.5
2.6
2.2.2.4 Maximum Volume of Heat Sink
19
Design Parameters
19
2.2.3.1 Fin Material
21
2.2.3.2 Number of Fins
21
2.2.3.3 Fin Shapes
21
2.2.3.4 Fin Alignments
21
2.2.3.5 Base Plate Thickness and Fin Height
22
2.2.3.6 Fin Efficiency
22
2.2.3.7 Fin Effectiveness
24
Material of Fins
25
2.3.1
Introduction
25
2.3.2
Aluminium
26
2.3 .3
Aluminium Alloy
27
2.3.4
Aluminium Alloy 6063
28
Heat Transfer Mechanisms
29
2.4.1
Introduction
29
2.4.2
Conduction
30
2.4.3
Convection
30
2.4.4
Radiation
32
Design Tool
33
2.5.1
Introduction
33
2.5.2
SolidWorks Software
33
Engineering Analysis Tools
34
2.6.1
Introduction
34
2.6.2
Steps in Finite Element Analysis
35
2.6.2.1 Preprocessing
35
2.6.2.2 Solution
35
2.6.2.l Post-processing
36
ANSYS
36
2.6.3.1 Thermal Analysis
37
2.6.3
2.6.3.1 .1 Steady State Condition and Transient Condition
38
2.6.3 .1.2 Temperature Distribution
38
2.6.3.1.3 Heat Flux
38
© Universiti Teknikal Malaysia Melaka
VI
2.6.4
Summary
39
CHAPTER3:METHODOLOGY
40
3.1
Overview Methodology
40
3.2
Phase 1
42
3.3
3.2.1
Introduction
42
3.2.2
Literature Review
42
Phase 2
3.3.1
3.4
3.5
43
Data Mining
43
3.3.1.1 Design Parameters of Fins
43
3.3.1.2 Uncertainty Heat Capacity for Fin Analysis
46
3.3.1.3 Material Used
46
3.3.2
3D Modeling
46
3.3.3
Formulation Analysis
47
3.3.3.1 Assumptions
48
3.3.3.2 Convection Heat Transfer Coefficient
48
Phase 3
50
3.4.1 Simulation
50
3.4.2
Steady State Thermal Analysis
51
3.4.2.1 Pre-Processing
52
3.4.2.2 Solution
55
3.4.2.3 Post-Processing
55
3.4.3
Static Structural
56
3.4.4
Selection of Fin Design
59
3.4.5
Proposed Design
60
3.4.6
Transient Thermal Analysis
62
Phase 4
64
3.5.1
Results and Discussions
64
3.5.2
Conclusion and Recommendation
64
CHAPTER 4: RES ULTS AND DISCUSSION
65
4.1
Steady State Thermal Analysis
65
4.1 .1 Temperature Distribution of Finned Heat Sinks
66
© Universiti Teknikal Malaysia Melaka
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4.1.2
Total Heat Flux of Finned Heat Sink
67
4.2
Static Structural Analysis
68
4.3
Fin Efficiency and Overall Fin Effectiveness
70
4.4
Selection of Fin Design
71
4.5
Transient Thermal Analysis
72
4.5.1
Temperature Distribution of Selected Fin Design
73
4.5.2
Total Heat Flux of Selected Fin Design
76
4.5.3
Temperature Distribution of Proposed Fin Design
80
4.5.4
Total Heat Flux of Proposed Fin Design
83
4.5.5
Comparison between Selected Finned Heat Sink and
Proposed Finned Heat Sink
4.6
Discussions
87
89
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
92
5.1
Conclusion
92
5.2
Recommendations
93
REFERENCES
94
APPENDICES
A
Gantt Chart
B
Properties of Aluminium Alloy 6063
C
Tabular Data for Properties of Air and Convection Heat Transfer Coefficient
D
Temperature Distribution and Total Heat Flux in Steady State Thermal
Analysis
E
Theoretical Calculations for Fin Efficiency and Overall Fin Effectiveness
F
Temperature Distribution in Transient Thermal Analysis
G
Total Heat Flux in Transient Thermal Analysis
H
Engineering Drawings
I
Results ofFEA
© Universiti Teknikal Malaysia Melaka
Vlll
LIST OF TABLES
2.1
Categories of Heat Sinks
9
2.2
Advantages & Disadvantages of Passive Cooling
11
2.3
Feature of Different Heat Sinks Types
12
2.4
Advantages and Disadvantages of Extruded Heat Sink
14
2.5
Main Alloying Elements in Wrought Alloy Designation System
27
2.6
Thermal Conductivity and Density of Some Materials
28
2.7
Emissivity of Common Aluminum Surface Finishes Compared to the
28
Blackbody
2.8
Difference between Natural Convection and Forced Convection
31
3.1
Dimensions of Finned Heat Sinks
43
3.2
Selection Criteria
59
4.1
Average Factor of Safety for Different Type of Heat Sinks
70
4.2
Summarized Result of Fin Efficiency and Effectiveness
70
4.3 (a)
Data Collection for Scoring
71
4.3 (b)
Weighted Scoring Model
71
4.4
Contour Plot of Temperature Distribution for Selected Splayed Finned
73
Heat Sink in 10 seconds
4.5
Contour Plot of Total Heat Flux for Selected Splayed Finned Heat Sink
77
in 10 seconds
4.6
Contour Plot of Temperature Distribution for Proposed Finned Heat
80
Sink in 10 seconds
4.7
Contour Plot of Total Heat Flux for Proposed Finned Heat Sink in 10
83
seconds
© Universiti Teknikal Malaysia Melaka
IX
LIST OF FIGURES
1.1
Thermal Flow Variation and CPU die size depending on the 2
production year
2.1
The Schematic Diagram of Different Fin Designs
14
2.2
Different Fin Profiles
15
2.3
Heat Sinks with Oblique/Splayed Plate and Pin Fins
15
2.4
The Schematic Diagram of Heat Sink Design
20
2.5
The Top-View and Side-View of Splayed Pin Finned Heat Sink
20
2.6
The Ideal and Actual Temperature Distribution in a Fin
23
2.7
The Effectiveness of a Fin
24
2.8
Difference between Heat Transfer Mechanisms
29
3.1
Process Development of Entire Project
41
3.2 (a)
Heat Sink with Plate Fins
44
3.2 (b)
Heat Sink with Strip Fins
45
3.2 (c)
Heat Sink with Splayed Fins
45
3.3
Steps of Drawing Creation Using SolidWorks
47
3.4
Heat Flow by Convection
49
3.5
Steps of Simulation Using ANSYS Software
51
3.6 (a)
Procedure in Conducting Steady State Thermal Analysis
52
3.6 (b)
Detail Steps in conducting Steady State Thermal Analysis
52
3.7
Meshing of Plate Finned Heat Sink
53
3.8 (a)
Temperature Setting
53
3.8 (b)
Temperature Applied
54
3.9 (a)
Convection Heat Transfer Coefficient Setting in form of Tabular Data
54
3.9 (b)
Convection Heat Transfer Applied
55
3.IO(a)
Procedure in Conducting Static Structural Analysis
56
3.10 (b)
Detail Steps in Conducting Static Structural Analysis
57
3.11
Contour Plot of Imported Body Temperature
57
3.12 (a)
Fixed Support Applied
58
© Universiti Teknikal Malaysia Melaka
x
3.12 (b)
Standard Earth Gravity Applied
58
3.13
The Proposed Splayed Finned Heat Sink with Perforations
61
3.14 (a)
Procedure in Conducting Transient Thermal Analysis
62
3.14 (b)
Detail Steps in Conducting Transient Thermal Analysis
63
3.15
Details of Initial Temperature in Transient Thermal Analysis
63
4.1
Comparison of Average Temperature Distributed on the Three
66
Finned Heat Sink at Different Ambient Temperature
4.2
Comparison of Average Total Heat Flux of the Three Finned Heat
67
Sink at Different Ambient Temperature
4.3 (a)
Factor of Safety for Plate Finned Heat Sink
68
4.3 (b)
Factor of Safety for Strip Finned Heat Sink
69
4.3 (c)
Factor of Safety for Splayed Finned Heat Sink
69
4.4
Contour Plot of Temperature Distribution for Selected Splayed
75
Finned Heat Sink in 10 seconds
4.5
Vector Plot of Total Heat Flux for Selected Finned Heat Sink
76
4.6
Comparison of Minimum and Maximum Total Heat Flux for Splayed
78
Finned Heat Sink
4.7
Comparison of Global Minimum and Maximum Temperature for
82
Proposed Finned Heat Sink
4.8
Vector Plot of Total Heat Flux for the Proposed Finned Heat Sink
83
4.9
Total Heat Flux in the Region of Perforations in 1 second
85
4.10
Comparison of Minimum and Maximum Total Heat Flux for
86
Proposed Finned Heat Sink
4.11
Comparison of the Average for Minimum and Maximum
87
Temperature in Both Finned Heat Sinks
4.12
Comparison of the Average for Minimum Total Heat Flux in Both
88
Finned Heat Sinks
© Universiti Teknikal Malaysia Melaka
Xl
LIST OF ABBREVIATIONS, SYMBOLS AND
NOMENCLATURE
2D
Two dimensional
30
Three dimensional
A
Fin surface area
Ab
Cross-sectional area of fin at the base
Ac
Cross-sectional area of fin
A fin
Total surface area of all the fins on that surface
Ano fin
Area of surface when there are no fins
Aun fin
Area of the unfinned surface portion
As
Heat transfer surface area
AA
Aluminium Association
Al
Aluminium
AN SYS
Analysis System
/3
Coefficient of volume expansion
CAD
Computer-Aided Design
CFD
computational fluid dynamics
CPU
central processing unit
et al
Et alia
etc
Et cetera
D
Diameter of cylindrical pin fin
FEA
Finite Element Analysis
FYP
Final Year Project
g
Gravitational acceleration
G
Interrupted length
GrL
Groshof number
h
Convection heat transfer coefficient
h
Base thickness
H
Fin height
IGES
Initial Graphics Exchange Specification
© Universiti Teknikal Malaysia Melaka
Xll
k
Thermal conductivity
K
Kelvin
L
Base length
Corrected length
Characteristic length of the geometry
Parameter in theoretical fin efficiency
m
meter
mm
millimeter
n
Number of fins
Nu
Nusselt number
q
Heat flux
Q
Heat flux rate
r'2conv
Rate of heat transfer by convection
Qfin
Actual heat transfer rate from the fin
Qfin,max
Ideal heat transfer rate from the fin if the entire fin were at base
temperature
r'2no fin
Rate of heat transfer if no fin is attached to the surface
r'2rad
Rate of heat transfer by radiation
r'2total,fin
Total rate of heat transfer from a finned surface
r'2total,no fin
Total rate of heat transfer from unfinned surface
RaL
Rayleigh number
Pr
Prandtl number
s
Fin spacing
Fin thickness
Base temperature
Film temperature
Surface Temperature
Ambient temperature
!:iT
temperature difference across the medium
v
Kinematic viscosity of the fluid
w
Fin length
w
Sink width
© Universiti Teknikal Malaysia Melaka
Xlll
VI
V/att
8
Splayed angle
TJ fin
Fin efficiency
T/adiabatic fin
Fin efficiency in adiabatic temperature
E
Emissivity of the surface
Efin
Fin effectiveness
a
Stefan-Boltzmann constant
°C
Degree Celsius
© Universiti Teknikal Malaysia Melaka
XIV
CHAPTER 1
INTRODUCTION
This chapter introduces the general idea of this project and provides the problem
statement, objectives, and project scope. This chapter also provides a report
organization to briefly introduce about the purpose of all the generated chapters.
1.1
Background
Nowadays, the new wave of computer technology makes a crucial impact on modern
world. Desktop computer is widely employed in state-of-the-art industry and more
data are capable to be processed with a tremendous speed due to rapid development
of IT. This capability not only leads to higher density of heat and increases heat
dissipation of personal computer, but also causes the temperature of central
processing unit (CPU) rises (Mohan & Govindarajan, 2010). Based on Figure 1.1,
the density of thermal flow is highly needed to concern, no matter what is the
manufactured CPU (Mihai, 2007). The high temperature of CPU seriously increases
its failure mode and also shortens its own life (Mohan & Govindarajan, 2010).
1
Figure 1.1: Thermal Flow Variation and CPU die size depending the production year (Mihai, 2007)
In order to ensure the device operates within safe temperature condition, heat sink a
structural device used removes heat from a functional electronic package to the
surrounding is required (Ekpu et al., 2011). Various heat sink design options have
been developed to offer efficient and economical solutions over the years (Eppes et
al., 2012). According to Huang & Chang (2012), there are a vast researchers has
been seen that a heat sink with excellent geometrical design will provide higher
efficiency and better cooling performance. A good design of heat sink should comply
with the related standards, and has good reliability and durability, manufacturability,
reasonable cost and etc., so that to meet the desired temperatures under the worst
working condition (Liu et al., 2012).
For the production of heat sinks, thermal management materials such as aluminium
are commonly used because they exhibit high thermal conductivity and reasonably
low coefficient of thermal expansion properties. Lower density thermal management
materials are preferred due to miniaturization of electronic devices at present (Ekpu
et al., 2011). Aluminium air-cooled heat sink has becomes one of the most
commonly used devices to cool CPUs because it leads to the advantageous of simple
maintenance process, more reliability, lower manufacturing cost, and no
environmental concerns. According to Das (2006), recycling aluminium alloys are
provided major economic benefits. Therefore, the aluminium alloy is definitely an
appropriate material for heat sink in considering the perspective of sustainable
development.
2
This paper focuses on three types of fin designs such as plate finned heat sink, in-line
strip finned heat sink, and splayed pin finned heat sink, which are the common types
used in the computer for CPU cooling. 3D SolidWorks models for the three fin
designs are presented and temperature distribution and total heat flux are predicted
for the heat sinks in a range of temperature using finite element analysis which is
implemented using ANSYS software. This project is proposed an improved design of
finned heat sink and it is compared to the other finned heat sink. Therefore, a fin
design which has the most excellent in thermal performance is obtained at the end of
this project. The aluminium alloy 6063 is used as material of fins, but the addition of
other metals in the amounts commonly used in aluminium alloys does not
appreciably change the density (EAA, 1994).
1.2
Problem Statement
Computers continue to get faster via smaller and more intricate circuitry, which
generates mass amounts of heat. Heat given off by processors must be dissipated to
prevent the electrical equipments operate slowly or malfunction. According to
Gurrum et al. (2004), heat dissipation rates for computer CPUs may increase as high
as 180 W for the next few years and as high as 288 W by the year 2016.
The finned heat sinks work under uncertainty conditions with fluctuated temperature
and heat capacity. Electrical equipments will failure in operation as the heat transfer
rate of finned heat sinks is much lower compared to the total heat released from CPU.
This had become the main problem which arises in designing fins with a desired
material. Therefore, thermal analysis on the fin designs are required to test the
thermal performance of fins under certain range of ambient temperature, as well as
the factor of safety and fin efficiency are analyzed under steady state and transient
condition respectively.
In addition to the present world, sustainable development of the environment has
become the pivotal political and social issue to solve the problems of destruction the
environment and natural resources. The selection of recyclable material for fin could
3
be a critical part, but the integration of appropriate material with the fin designs and
analyzed under uncertainty heat capacity has becomes more challenging. Therefore,
a high thermal conductivity material is required so the fins can resist under any
temperature.
1.3
Objectives
The objectives of this project are
a) To investigate the design parameters of fins.
b) To analyze the uncertainty heat capacity for fins using engineering analysis
software.
c) To design of fins under uncertainty heat capacity.
1.4
Scope of Project
This project focuses the design of finned heat sink used in the cooling of central
processing unit (CPU) for computer. There are many different designs of finned heat
sink commercially available in the market, but only three existing designs which are
the heat sinks with plate fins, in-line strip fins, and splayed pin fins are investigated
under natural convection. Aluminium alloy 6063-O is used as the only and desirable
material for the three fin designs for further simulation and analysis.
The performance of a heat sink is affected by various parameters such as fin shapes,
fin arrangement or alignment; base length (L), fin height (H), fin thickness (t), sink
width (W), fin spacing (s), base thickness (h), fin length (w) and number of fins (n)
which all are measured in unit of millimeter (mm). These parameters can considered
as the performance improvement paths for the selected heat sinks. Many design
constraints such as heat transfer surface area (A), heat transfer coefficient (h), ambient
temperature (T∞), surface temperature of fin (TS), and thermal conductivity (k) are also
4
explored and attention is focused on the selection of fin designs under uncertainty heat
capacity.
Three dimensional (3D) fin design models are generated using SolidWorks 2010
software and the simulations are conducted with the aids of ANSYS software.
Thermal analysis is conducted respectively under steady state condition and transient
condition that involves conduction and convection phenomena.
Thermal analysis of the three fin models was first conducted under steady state
condition at different ambient temperature to analyze the temperature distribution,
total heat flux, and factor of safety of finned heat sink. The results from the
simulations are analyzed and discussed; therefore, the best among the three fin
models can be selected by weighted scoring method. Besides, an improved design of
finned heat sink is proposed based on the comparison of the candidate fin models.
The selected fin design and proposed fin design are then analyzed under transient
condition. This analysis is required to predict the temperature distribution and total
heat flux of the heat sink body which are vary with time. The results of simulation
for both fin models are analyzed and compared so that a fin design with the best
thermal performance is selected at the end of this project.
1.5
Project Organization
This report is divided into five different chapters which are completed within the
duration of one year. These chapters are briefly introduced and described at below:
(a) Chapter 1 - Introduction
Chapter 1 proposes an overview for the entire project and shows the systematic
plan to conduct this project. This chapter involves the project background,
problem statements, objectives, scope of project, project organization. The Gantt
chart illustrates the activity planning of FYP I and FYP II is attached at Appendix
A.
5
(b) Chapter 2 - Literature Review
Chapter 2 provides the explanations of fins used in the cooling of CPU in
computer, fin designs, design principles, heat capacity and the material used,
aluminium alloy 6063 is used for the fin designs. This chapter provides also the
reviews of the software, including SolidWorks 2010 and ANSYS software. The
information regarding to each element which includes introduction, properties,
and some applications are obtained from the past studies, journals, books and
articles to help in understanding more about the elements that involved in this
project and as the guidance for the project flow. Relevant methods used by other
researchers are reviewed and compared in order to act as guideline to solve the
problems and to achieve the objectives.
(c) Chapter 3 - Research Methodology
Chapter 3 is described the methodology used to solve the problems and to
achieve the objectives. A flow chart is generated with its descriptions to show the
process flow and methodology that used as a guideline for this project. In this
chapter, the relevant variables and elements are defined in detail together with the
engineering sketching of three different fin designs.
(d) Chapter 4 - Result and Discussion
Chapter 4 describes the implementation of the methodology which had proposed
in Chapter 3 to obtain three detail designs of fin and their accurate data through
the uses of design and analysis software. The results are then to be explained and
compared between each other using the relevant variables. The weighted scoring
method is implemented for the selection of design. Lastly, the best fin design is
selected based on the analysis and it is investigated and compared with proposed
design through simulation. Finally, only one with best performance is chosen.
(e) Chapter 5 - Conclusion
Chapter 5 is the last chapter which conclude the overall findings of the entire
project and the most excellent design of fins is obtained. This chapter provides
also the recommendation for future research.
6
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
DESIGN AND ANALYSIS OF FINS UNDER UNCERTAINTY HEAT
CAPACITY
This repott submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Design) (Hons.)
by
CHONG SEE YING
B051010010
890316-59-5344
FACULTY OF MANUFACTURING ENGINEERING
2014
© Universiti Teknikal Malaysia Melaka
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: DESIGN AND ANALYSIS OF FINS UNDER UNCERTAINTY HEAT
CAPACITY
SESI PENGAJIAN: 2013/14 Semester 2
Saya CHONG SEE YING
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti
Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Sila tandakan ( ./)
D
SULIT
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysia sebagaimana yang termaktub
dalam AKTA RAHSIA RASMI 1972)
TERHAD
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkan oleh:
ｾＭ
Alamat Tetap:
Cop Rasmi:
NO. 4, TAMAN NAGAMAS,
71650 TITI,
JELEBU, NEGERI SEMBILAN
DR. TAUFIK
Senior Lecturer
Faculty of Manufacturing Engineerfn1
. Unlverslti Teknikal Malaysia Melaall
Hang Tuah Jaya
76100 Durian Tunggal, Melab
Tarikh: 23 MAY 2014
** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
C Universiti Teknikal Malaysia Melaka
DECLARATION
I hereby, declared this report entitled "Design and Analysis of Fins under
Uncertainty Heat Capacity" is the results of my own research except as cited in
references.
Signature
Author's Name
CHONG SEE YING
Date
261h JUNE 2014
© Universiti Teknikal Malaysia Melaka
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM
as a partial fulfillment of the requirements for the degree of Bachelor of
Manufacturing Engineering (Manufacturing Design) (Hons.). The member of
the supervisory committee is as follow:
ﾷ ﾷｾＭ＠
ｾＯ＠
DR. TAUFIK
ｾｮｩｯｲ＠
Lectunr
Faculty of Manufacturing Engineerinf
Unlvenlti Teknikal Malaysia Mel.ta
Hang Tuah Jaya
76100 Durian Tunggal, Melab
© Universiti Teknikal Malaysia Melaka
ABSTRAK
Project ini terutamanya memberi pertumpuan atas reka bentuk sirip dan analisis
untuk sirip di bawah kapasitas haba yang tidak menentu. Tiga sink haba yang
bersirip dengan mempunyai geometri yang berbeza tetapi mempunyai volume yang
sama telah dipilih. Beberapa parameter yang berkaitan dengan reka bentuk sirip telah
dikenal pasti dan dipertimbangkan dengan dimensi geometri meraka. Kekangan
system seperti suhu operasi yang tertinggi pada unit pusat pemprosesan dan suhu
udara yang menyelilingi sinki haba juga telah dikenalkan sebelum simulasi
dijalankan. Aloi Aluminium 6063 yang mempunyai keberaliran haba yang dikira
cukup tinggi telah digunakan sebagai bahan untuk sinki haba yang bersirip. Lakaran
bagi model-model sirip telah dibuat untuk menjadikan reka bentuk tertentu sebagai
konsep pada peringkat awal project ini. SolidWorks 2010 yang merupakan salah
sebuah perisian CAD yang digunakan untuk menghasilkan model-model 3D bagi
reka bentuk sirip. Analisis unsur terhingga telah dijalankan dengan menggunakan
perisian ANSYS. Pada peringkat awalnya, tiga model sirip 3D, contohnya sink haba
yang bersirip plat, jalur dan splayed dianalisis di bawah keadaan yang mantap
bertujuan untuk mengaji taburan suhu dan jumlah fluks haba. Manakala, analisis
struktur static dilakukan juga untuk mendapatkan factor keselamatan bagi ketiga-tiga
sink haba bersirip. Model pemarkahan wajaran dihasilkan dengan merujuk kepada
criteria yang berkaitan. Kemudian, haba tenggelam bersirip splayed telah dipilih
sebagai reka bentuk sirip yang terbaik dan reka bentuk sirip yang lebih baik
dicadangkan berdasarkan penemuan daripada analisis keadaan mantap. Analisis fana
haba sink bersirip telah terpilih dan haba tengelam bersirip dengan tebukan telah
dijalankan masing-masing. Hasilnya, haba tenggelam bersirip berlubang telah dipilih
sebagai reka bentuk yang paling unggul dalam erti prestasi terma.
© Universiti Teknikal Malaysia Melaka
ABSTRACT
This project primarily focuses on the design and analysis of fins under uncertainty
heat capacity. Three finned heat sinks with different geometry are selected at a fixed
volume. The design parameters of fins are identified and considered with geometrical
dimensions through reviewed literature. System constraints such as maximum
operating temperature of central processing unit and air temperature surrounding the
heat sink are also defined before simulation. Aluminium alloy 6063 which has
considerably high thermal conductivity is used as the material of finned heat sink.
CAD software which is SolidWorks 2010 is used to conduct 3D modeling of the fin
designs. Finite element analysis is performed by using ANSYS software. At first, the
3D fin models which including heat sinks with plate fins, strip fins, and splayed are
analyzed under steady state condition in order to investigate their temperature
distribution and total heat flux. However, static structural analysis is performed also
to obtain the factor of safety for each fin design. Weighted scoring model is
generated by referring to the relevant criteria. In addition, the splayed finned heat
sink is chosen as the best fin design and an improved design is proposed based on the
findings from the steady state analysis. Transient thermal analysis of the selected
finned heat sink and proposed finned heat sink with perforations is conducted
respectively. As a result, the perforated finned heat sink is selected as the most
superior design in sense of thermal performance.
© Universiti Teknikal Malaysia Melaka
11
DEDICATION
To my beloved parents, siblings and friends due to their love and support.
© Universiti Teknikal Malaysia Melaka
Ill
ACKNOWLEDGEMENT
I would like to express my deep gratitude to Dr. Taufik, my supervisor for his patient
guidance, useful advice, and assistance along the progress of this project. I am
grateful for his professionalism and his tolerance to guide me.
My grateful thanks are also extended to my parents and all my family members for
their love, support and concerns.
Besides, I would also like to thank to my fellow friends who kindly provide
assistance and support to me without hesitations.
© Universiti Teknikal Malaysia Melaka
lV
TABLE OF CONTENTS
Abstrak
Abstract
11
Dedication
111
Acknowledgement
lV
Table of Contents
v
List of Tables
lX
List of Figures
x
List of Abbreviations, Symbols and Nomenclature
Xll
CHAPTER 1: INTRODUCTION
1
1.1
Background
1
1.2
Problem Statement
3
1.3
Objectives
4
1.4
Scope of Project
4
1.5
Project Organization
5
CHAPTER 2: LITERATURE REVIEW
7
2.1
Overview of Finned Heat Sink
7
2.1.1
Introduction
7
2.1.2
Categories of Heat Sinks
8
2.1.3
Types of Heat Sinks
11
2.1.4
Fin Designs
13
2.1.5
Overview of Fin Designs
16
2.2
Fin Design Principles
17
2.2.1
Introduction
17
2.2.2
System Constraints
17
2.2.2.1 Ambient Temperature
18
2.2.2.2 Maximum Operating Temperature
18
2.2.2.3 Heat Removal Capability
18
© Universiti Teknikal Malaysia Melaka
v
2.2.3
2.3
2.4
2.5
2.6
2.2.2.4 Maximum Volume of Heat Sink
19
Design Parameters
19
2.2.3.1 Fin Material
21
2.2.3.2 Number of Fins
21
2.2.3.3 Fin Shapes
21
2.2.3.4 Fin Alignments
21
2.2.3.5 Base Plate Thickness and Fin Height
22
2.2.3.6 Fin Efficiency
22
2.2.3.7 Fin Effectiveness
24
Material of Fins
25
2.3.1
Introduction
25
2.3.2
Aluminium
26
2.3 .3
Aluminium Alloy
27
2.3.4
Aluminium Alloy 6063
28
Heat Transfer Mechanisms
29
2.4.1
Introduction
29
2.4.2
Conduction
30
2.4.3
Convection
30
2.4.4
Radiation
32
Design Tool
33
2.5.1
Introduction
33
2.5.2
SolidWorks Software
33
Engineering Analysis Tools
34
2.6.1
Introduction
34
2.6.2
Steps in Finite Element Analysis
35
2.6.2.1 Preprocessing
35
2.6.2.2 Solution
35
2.6.2.l Post-processing
36
ANSYS
36
2.6.3.1 Thermal Analysis
37
2.6.3
2.6.3.1 .1 Steady State Condition and Transient Condition
38
2.6.3 .1.2 Temperature Distribution
38
2.6.3.1.3 Heat Flux
38
© Universiti Teknikal Malaysia Melaka
VI
2.6.4
Summary
39
CHAPTER3:METHODOLOGY
40
3.1
Overview Methodology
40
3.2
Phase 1
42
3.3
3.2.1
Introduction
42
3.2.2
Literature Review
42
Phase 2
3.3.1
3.4
3.5
43
Data Mining
43
3.3.1.1 Design Parameters of Fins
43
3.3.1.2 Uncertainty Heat Capacity for Fin Analysis
46
3.3.1.3 Material Used
46
3.3.2
3D Modeling
46
3.3.3
Formulation Analysis
47
3.3.3.1 Assumptions
48
3.3.3.2 Convection Heat Transfer Coefficient
48
Phase 3
50
3.4.1 Simulation
50
3.4.2
Steady State Thermal Analysis
51
3.4.2.1 Pre-Processing
52
3.4.2.2 Solution
55
3.4.2.3 Post-Processing
55
3.4.3
Static Structural
56
3.4.4
Selection of Fin Design
59
3.4.5
Proposed Design
60
3.4.6
Transient Thermal Analysis
62
Phase 4
64
3.5.1
Results and Discussions
64
3.5.2
Conclusion and Recommendation
64
CHAPTER 4: RES ULTS AND DISCUSSION
65
4.1
Steady State Thermal Analysis
65
4.1 .1 Temperature Distribution of Finned Heat Sinks
66
© Universiti Teknikal Malaysia Melaka
Vll
4.1.2
Total Heat Flux of Finned Heat Sink
67
4.2
Static Structural Analysis
68
4.3
Fin Efficiency and Overall Fin Effectiveness
70
4.4
Selection of Fin Design
71
4.5
Transient Thermal Analysis
72
4.5.1
Temperature Distribution of Selected Fin Design
73
4.5.2
Total Heat Flux of Selected Fin Design
76
4.5.3
Temperature Distribution of Proposed Fin Design
80
4.5.4
Total Heat Flux of Proposed Fin Design
83
4.5.5
Comparison between Selected Finned Heat Sink and
Proposed Finned Heat Sink
4.6
Discussions
87
89
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
92
5.1
Conclusion
92
5.2
Recommendations
93
REFERENCES
94
APPENDICES
A
Gantt Chart
B
Properties of Aluminium Alloy 6063
C
Tabular Data for Properties of Air and Convection Heat Transfer Coefficient
D
Temperature Distribution and Total Heat Flux in Steady State Thermal
Analysis
E
Theoretical Calculations for Fin Efficiency and Overall Fin Effectiveness
F
Temperature Distribution in Transient Thermal Analysis
G
Total Heat Flux in Transient Thermal Analysis
H
Engineering Drawings
I
Results ofFEA
© Universiti Teknikal Malaysia Melaka
Vlll
LIST OF TABLES
2.1
Categories of Heat Sinks
9
2.2
Advantages & Disadvantages of Passive Cooling
11
2.3
Feature of Different Heat Sinks Types
12
2.4
Advantages and Disadvantages of Extruded Heat Sink
14
2.5
Main Alloying Elements in Wrought Alloy Designation System
27
2.6
Thermal Conductivity and Density of Some Materials
28
2.7
Emissivity of Common Aluminum Surface Finishes Compared to the
28
Blackbody
2.8
Difference between Natural Convection and Forced Convection
31
3.1
Dimensions of Finned Heat Sinks
43
3.2
Selection Criteria
59
4.1
Average Factor of Safety for Different Type of Heat Sinks
70
4.2
Summarized Result of Fin Efficiency and Effectiveness
70
4.3 (a)
Data Collection for Scoring
71
4.3 (b)
Weighted Scoring Model
71
4.4
Contour Plot of Temperature Distribution for Selected Splayed Finned
73
Heat Sink in 10 seconds
4.5
Contour Plot of Total Heat Flux for Selected Splayed Finned Heat Sink
77
in 10 seconds
4.6
Contour Plot of Temperature Distribution for Proposed Finned Heat
80
Sink in 10 seconds
4.7
Contour Plot of Total Heat Flux for Proposed Finned Heat Sink in 10
83
seconds
© Universiti Teknikal Malaysia Melaka
IX
LIST OF FIGURES
1.1
Thermal Flow Variation and CPU die size depending on the 2
production year
2.1
The Schematic Diagram of Different Fin Designs
14
2.2
Different Fin Profiles
15
2.3
Heat Sinks with Oblique/Splayed Plate and Pin Fins
15
2.4
The Schematic Diagram of Heat Sink Design
20
2.5
The Top-View and Side-View of Splayed Pin Finned Heat Sink
20
2.6
The Ideal and Actual Temperature Distribution in a Fin
23
2.7
The Effectiveness of a Fin
24
2.8
Difference between Heat Transfer Mechanisms
29
3.1
Process Development of Entire Project
41
3.2 (a)
Heat Sink with Plate Fins
44
3.2 (b)
Heat Sink with Strip Fins
45
3.2 (c)
Heat Sink with Splayed Fins
45
3.3
Steps of Drawing Creation Using SolidWorks
47
3.4
Heat Flow by Convection
49
3.5
Steps of Simulation Using ANSYS Software
51
3.6 (a)
Procedure in Conducting Steady State Thermal Analysis
52
3.6 (b)
Detail Steps in conducting Steady State Thermal Analysis
52
3.7
Meshing of Plate Finned Heat Sink
53
3.8 (a)
Temperature Setting
53
3.8 (b)
Temperature Applied
54
3.9 (a)
Convection Heat Transfer Coefficient Setting in form of Tabular Data
54
3.9 (b)
Convection Heat Transfer Applied
55
3.IO(a)
Procedure in Conducting Static Structural Analysis
56
3.10 (b)
Detail Steps in Conducting Static Structural Analysis
57
3.11
Contour Plot of Imported Body Temperature
57
3.12 (a)
Fixed Support Applied
58
© Universiti Teknikal Malaysia Melaka
x
3.12 (b)
Standard Earth Gravity Applied
58
3.13
The Proposed Splayed Finned Heat Sink with Perforations
61
3.14 (a)
Procedure in Conducting Transient Thermal Analysis
62
3.14 (b)
Detail Steps in Conducting Transient Thermal Analysis
63
3.15
Details of Initial Temperature in Transient Thermal Analysis
63
4.1
Comparison of Average Temperature Distributed on the Three
66
Finned Heat Sink at Different Ambient Temperature
4.2
Comparison of Average Total Heat Flux of the Three Finned Heat
67
Sink at Different Ambient Temperature
4.3 (a)
Factor of Safety for Plate Finned Heat Sink
68
4.3 (b)
Factor of Safety for Strip Finned Heat Sink
69
4.3 (c)
Factor of Safety for Splayed Finned Heat Sink
69
4.4
Contour Plot of Temperature Distribution for Selected Splayed
75
Finned Heat Sink in 10 seconds
4.5
Vector Plot of Total Heat Flux for Selected Finned Heat Sink
76
4.6
Comparison of Minimum and Maximum Total Heat Flux for Splayed
78
Finned Heat Sink
4.7
Comparison of Global Minimum and Maximum Temperature for
82
Proposed Finned Heat Sink
4.8
Vector Plot of Total Heat Flux for the Proposed Finned Heat Sink
83
4.9
Total Heat Flux in the Region of Perforations in 1 second
85
4.10
Comparison of Minimum and Maximum Total Heat Flux for
86
Proposed Finned Heat Sink
4.11
Comparison of the Average for Minimum and Maximum
87
Temperature in Both Finned Heat Sinks
4.12
Comparison of the Average for Minimum Total Heat Flux in Both
88
Finned Heat Sinks
© Universiti Teknikal Malaysia Melaka
Xl
LIST OF ABBREVIATIONS, SYMBOLS AND
NOMENCLATURE
2D
Two dimensional
30
Three dimensional
A
Fin surface area
Ab
Cross-sectional area of fin at the base
Ac
Cross-sectional area of fin
A fin
Total surface area of all the fins on that surface
Ano fin
Area of surface when there are no fins
Aun fin
Area of the unfinned surface portion
As
Heat transfer surface area
AA
Aluminium Association
Al
Aluminium
AN SYS
Analysis System
/3
Coefficient of volume expansion
CAD
Computer-Aided Design
CFD
computational fluid dynamics
CPU
central processing unit
et al
Et alia
etc
Et cetera
D
Diameter of cylindrical pin fin
FEA
Finite Element Analysis
FYP
Final Year Project
g
Gravitational acceleration
G
Interrupted length
GrL
Groshof number
h
Convection heat transfer coefficient
h
Base thickness
H
Fin height
IGES
Initial Graphics Exchange Specification
© Universiti Teknikal Malaysia Melaka
Xll
k
Thermal conductivity
K
Kelvin
L
Base length
Corrected length
Characteristic length of the geometry
Parameter in theoretical fin efficiency
m
meter
mm
millimeter
n
Number of fins
Nu
Nusselt number
q
Heat flux
Q
Heat flux rate
r'2conv
Rate of heat transfer by convection
Qfin
Actual heat transfer rate from the fin
Qfin,max
Ideal heat transfer rate from the fin if the entire fin were at base
temperature
r'2no fin
Rate of heat transfer if no fin is attached to the surface
r'2rad
Rate of heat transfer by radiation
r'2total,fin
Total rate of heat transfer from a finned surface
r'2total,no fin
Total rate of heat transfer from unfinned surface
RaL
Rayleigh number
Pr
Prandtl number
s
Fin spacing
Fin thickness
Base temperature
Film temperature
Surface Temperature
Ambient temperature
!:iT
temperature difference across the medium
v
Kinematic viscosity of the fluid
w
Fin length
w
Sink width
© Universiti Teknikal Malaysia Melaka
Xlll
VI
V/att
8
Splayed angle
TJ fin
Fin efficiency
T/adiabatic fin
Fin efficiency in adiabatic temperature
E
Emissivity of the surface
Efin
Fin effectiveness
a
Stefan-Boltzmann constant
°C
Degree Celsius
© Universiti Teknikal Malaysia Melaka
XIV
CHAPTER 1
INTRODUCTION
This chapter introduces the general idea of this project and provides the problem
statement, objectives, and project scope. This chapter also provides a report
organization to briefly introduce about the purpose of all the generated chapters.
1.1
Background
Nowadays, the new wave of computer technology makes a crucial impact on modern
world. Desktop computer is widely employed in state-of-the-art industry and more
data are capable to be processed with a tremendous speed due to rapid development
of IT. This capability not only leads to higher density of heat and increases heat
dissipation of personal computer, but also causes the temperature of central
processing unit (CPU) rises (Mohan & Govindarajan, 2010). Based on Figure 1.1,
the density of thermal flow is highly needed to concern, no matter what is the
manufactured CPU (Mihai, 2007). The high temperature of CPU seriously increases
its failure mode and also shortens its own life (Mohan & Govindarajan, 2010).
1
Figure 1.1: Thermal Flow Variation and CPU die size depending the production year (Mihai, 2007)
In order to ensure the device operates within safe temperature condition, heat sink a
structural device used removes heat from a functional electronic package to the
surrounding is required (Ekpu et al., 2011). Various heat sink design options have
been developed to offer efficient and economical solutions over the years (Eppes et
al., 2012). According to Huang & Chang (2012), there are a vast researchers has
been seen that a heat sink with excellent geometrical design will provide higher
efficiency and better cooling performance. A good design of heat sink should comply
with the related standards, and has good reliability and durability, manufacturability,
reasonable cost and etc., so that to meet the desired temperatures under the worst
working condition (Liu et al., 2012).
For the production of heat sinks, thermal management materials such as aluminium
are commonly used because they exhibit high thermal conductivity and reasonably
low coefficient of thermal expansion properties. Lower density thermal management
materials are preferred due to miniaturization of electronic devices at present (Ekpu
et al., 2011). Aluminium air-cooled heat sink has becomes one of the most
commonly used devices to cool CPUs because it leads to the advantageous of simple
maintenance process, more reliability, lower manufacturing cost, and no
environmental concerns. According to Das (2006), recycling aluminium alloys are
provided major economic benefits. Therefore, the aluminium alloy is definitely an
appropriate material for heat sink in considering the perspective of sustainable
development.
2
This paper focuses on three types of fin designs such as plate finned heat sink, in-line
strip finned heat sink, and splayed pin finned heat sink, which are the common types
used in the computer for CPU cooling. 3D SolidWorks models for the three fin
designs are presented and temperature distribution and total heat flux are predicted
for the heat sinks in a range of temperature using finite element analysis which is
implemented using ANSYS software. This project is proposed an improved design of
finned heat sink and it is compared to the other finned heat sink. Therefore, a fin
design which has the most excellent in thermal performance is obtained at the end of
this project. The aluminium alloy 6063 is used as material of fins, but the addition of
other metals in the amounts commonly used in aluminium alloys does not
appreciably change the density (EAA, 1994).
1.2
Problem Statement
Computers continue to get faster via smaller and more intricate circuitry, which
generates mass amounts of heat. Heat given off by processors must be dissipated to
prevent the electrical equipments operate slowly or malfunction. According to
Gurrum et al. (2004), heat dissipation rates for computer CPUs may increase as high
as 180 W for the next few years and as high as 288 W by the year 2016.
The finned heat sinks work under uncertainty conditions with fluctuated temperature
and heat capacity. Electrical equipments will failure in operation as the heat transfer
rate of finned heat sinks is much lower compared to the total heat released from CPU.
This had become the main problem which arises in designing fins with a desired
material. Therefore, thermal analysis on the fin designs are required to test the
thermal performance of fins under certain range of ambient temperature, as well as
the factor of safety and fin efficiency are analyzed under steady state and transient
condition respectively.
In addition to the present world, sustainable development of the environment has
become the pivotal political and social issue to solve the problems of destruction the
environment and natural resources. The selection of recyclable material for fin could
3
be a critical part, but the integration of appropriate material with the fin designs and
analyzed under uncertainty heat capacity has becomes more challenging. Therefore,
a high thermal conductivity material is required so the fins can resist under any
temperature.
1.3
Objectives
The objectives of this project are
a) To investigate the design parameters of fins.
b) To analyze the uncertainty heat capacity for fins using engineering analysis
software.
c) To design of fins under uncertainty heat capacity.
1.4
Scope of Project
This project focuses the design of finned heat sink used in the cooling of central
processing unit (CPU) for computer. There are many different designs of finned heat
sink commercially available in the market, but only three existing designs which are
the heat sinks with plate fins, in-line strip fins, and splayed pin fins are investigated
under natural convection. Aluminium alloy 6063-O is used as the only and desirable
material for the three fin designs for further simulation and analysis.
The performance of a heat sink is affected by various parameters such as fin shapes,
fin arrangement or alignment; base length (L), fin height (H), fin thickness (t), sink
width (W), fin spacing (s), base thickness (h), fin length (w) and number of fins (n)
which all are measured in unit of millimeter (mm). These parameters can considered
as the performance improvement paths for the selected heat sinks. Many design
constraints such as heat transfer surface area (A), heat transfer coefficient (h), ambient
temperature (T∞), surface temperature of fin (TS), and thermal conductivity (k) are also
4
explored and attention is focused on the selection of fin designs under uncertainty heat
capacity.
Three dimensional (3D) fin design models are generated using SolidWorks 2010
software and the simulations are conducted with the aids of ANSYS software.
Thermal analysis is conducted respectively under steady state condition and transient
condition that involves conduction and convection phenomena.
Thermal analysis of the three fin models was first conducted under steady state
condition at different ambient temperature to analyze the temperature distribution,
total heat flux, and factor of safety of finned heat sink. The results from the
simulations are analyzed and discussed; therefore, the best among the three fin
models can be selected by weighted scoring method. Besides, an improved design of
finned heat sink is proposed based on the comparison of the candidate fin models.
The selected fin design and proposed fin design are then analyzed under transient
condition. This analysis is required to predict the temperature distribution and total
heat flux of the heat sink body which are vary with time. The results of simulation
for both fin models are analyzed and compared so that a fin design with the best
thermal performance is selected at the end of this project.
1.5
Project Organization
This report is divided into five different chapters which are completed within the
duration of one year. These chapters are briefly introduced and described at below:
(a) Chapter 1 - Introduction
Chapter 1 proposes an overview for the entire project and shows the systematic
plan to conduct this project. This chapter involves the project background,
problem statements, objectives, scope of project, project organization. The Gantt
chart illustrates the activity planning of FYP I and FYP II is attached at Appendix
A.
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(b) Chapter 2 - Literature Review
Chapter 2 provides the explanations of fins used in the cooling of CPU in
computer, fin designs, design principles, heat capacity and the material used,
aluminium alloy 6063 is used for the fin designs. This chapter provides also the
reviews of the software, including SolidWorks 2010 and ANSYS software. The
information regarding to each element which includes introduction, properties,
and some applications are obtained from the past studies, journals, books and
articles to help in understanding more about the elements that involved in this
project and as the guidance for the project flow. Relevant methods used by other
researchers are reviewed and compared in order to act as guideline to solve the
problems and to achieve the objectives.
(c) Chapter 3 - Research Methodology
Chapter 3 is described the methodology used to solve the problems and to
achieve the objectives. A flow chart is generated with its descriptions to show the
process flow and methodology that used as a guideline for this project. In this
chapter, the relevant variables and elements are defined in detail together with the
engineering sketching of three different fin designs.
(d) Chapter 4 - Result and Discussion
Chapter 4 describes the implementation of the methodology which had proposed
in Chapter 3 to obtain three detail designs of fin and their accurate data through
the uses of design and analysis software. The results are then to be explained and
compared between each other using the relevant variables. The weighted scoring
method is implemented for the selection of design. Lastly, the best fin design is
selected based on the analysis and it is investigated and compared with proposed
design through simulation. Finally, only one with best performance is chosen.
(e) Chapter 5 - Conclusion
Chapter 5 is the last chapter which conclude the overall findings of the entire
project and the most excellent design of fins is obtained. This chapter provides
also the recommendation for future research.
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