||FABRICATION AND TEST OF VAPOR CHAMBER HEAT SPREADER
||Department of Mechanical and Electro-Mechanical Engineering
Plate Heat Pipe
||本論文對蒸汽腔體均溫板（Vapor Chamber Heat Spreader, VCHS）提出廣泛性的研究工作。研製多種規格的均溫板，探討工作流體充填率與其熱傳性能的變化。並透過實驗數據分析均溫板在電子冷卻應用的影響。
研究改變五個不同的均溫板傾斜角(0°, 45°, 90°, 135°, 180°)，結果顯示在不同的傾斜角度重力對均溫板熱傳性能的影響不大，僅在90°垂直擺放時有些微差距，顯示均溫板有很好的抗重力效果。
||This dissertation presents a comprehensive research work on the vapor chamber heat spreader (VCHS). Base on the experimental data this study try to regarding parametric effects of VCHS to the electronic cooling applications. A series of prototype vapor chamber heat spreaders with different working fluid filling ratios have been fabricated and tested their thermal performances.
To investigate the influence of the gravity on the VCHS performance, some tests were conducted under 0, 45, 90, 135, and 180 degree, five different tilt angles. It was shown that they have almost the same performance, and with little difference for the case of vertical install. The results also showed that the spreading resistance has the same trend with total thermal resistance which is a combination of the one-dimension, spreading, and condensing resistance. The spreading resistance is the dominating factor in determining the overall thermal resistance of a vapor chamber. VCHS can enhance the system performance both in air and water cooling tests.
In this research, several VCHS with heat sink design and simulation works have been done for potential industrial applications. VCHS shows great performance under multiple heat sources condition and replaces traditional cooling modules in Blade Server, Communication System and multiple LED chips effectively.
||Table of Contents
Table of Contents viii
List of Figures xi
List of Tables xv
Chapter 1 Introduction 1
1.1 Rationale for implementation of VCHS 1
1.2 Micro Channel Heat Pipe 2
1.3 Review of Characteristic Experiments on VCHS 9
1.4 Review of Simulation Works on VCHS 14
1.5 Spreading Resistance on VCHS 20
1.6 Motivation and Contents of the Study 24
Chapter 2 General Structure, Theory and Application 26
2.1 General structure of VCHS 26
2.2 Theory 28
2.2.1 General VCHS structure 28
2.2.2 Static Condition 30
2.2.3 Capillary pressure in porous 34
2.2.4 General Equation 44
2.2.5 Limits of VCHS 46
2.3 Applications 47
2.3.1 Factories in the world 47
2.3.2 Industrial applications 51
Chapter 3 Experimental Setup and Methodology 55
3.1 Thermal Performance Test 55
3.2 Variable Gravity Experiments 66
3.3 The Effect of a Cooling System with VCHS 71
3.3.1 Air cooling condenser testing 72
3.3.2 Water cooling condenser testing 74
3.3.3 VCHS enhanced the performance of heat sink 75
Chapter 4 Potential Industrial Applications 76
4.1 VCHS Size Effect in Blade Server System 76
4.2 Unsymmetrical Heat Sources with different level 79
4.3 Simulation of Intel 1366 CPU and BX924 CPU 82
4.3.1 VCHS-Heat Sink application on Intel 1366 CPU 82
4.3.2 VCHS-Heat Sink application on BX924 CPU 88
4.4 LED Lighting Applications 89
4.5 Low Cost VCHS 95
Chapter 5 Conclusions and Future Work 97
5.1 Vapor Chamber Heat Spreader 97
5.1.1 Domination of spreading resistance 97
5.1.2 Little effect on different orientations 97
5.1.3 Performance Enhancement by VCHS 98
5.1.4 VCHS for industrial application 99
5.1.5 Simulation work 99
5.2 Anticipated Benefits 100
5.3 Directions for Future Research Work 101
5.3.1 Multiple Heat Sources Solution 101
5.3.2 Heat transfer on thin film heat evaporation of VCHS 106
5.3.3 Instant Temperature used on PCR machine 107
Personal Publication 122
List of Figures
Figure 1 Flat plate micro heat spreader 5
Figure 2 Fabrication of micro heat spreader by Kovar metal 5
Figure 3 Radial grooved micro heat pipes (MHPs) 6
Figure 4 Flat miniature heat pipes with micro capillary grooves 6
Figure 5 A roll bond heat pipe (RBHP) which have 24 capillary grooves 6
Figure 6 Mesh screen and micro channel plate heat pipe 7
Figure 7 Film type heat pipe (FTHP) 7
Figure 8 Mesh screen and channels heat spreader 7
Figure 9 Observation of three layer vapor chamber heat spreader 8
Figure 10 High performance vapor chamber with triangular grooves 8
Figure 11 Schematic of pulsating/oscillation heat spreader 8
Figure 12 Wire mini heat pipe 11
Figure 13 Ultra-thin sheet-shaped heat pipe 11
Figure 14 Photograph of the experimental setup and dimensions 11
Figure 15 Top view and cross section of the vapor chamber 12
Figure 16 Photograph of the aluminum VCHS with cored-wires (RCW) 12
Figure 17 Schematic of a micro channel with sintered wicks VCHS 12
Figure 18 The correlation between evaporation resistance and water film 13
Figure 19 Mathematical model and boundary condition 15
Figure 20 Transformation of square into circular geometry 21
Figure 21 Non-square thermal spreader plate geometry 23
Figure 22 Simplified cross section schematic of the VCHS module 26
Figure 23 The exploded view of a VCHS feature 27
Figure 24 Manufacturing Process Flow Chart 27
Figure 25 Disc planner vapor chamber heat spreader structure 29
Figure 26 Dimensionless chat of VCHS sizing at 70 C 33
Figure 27 Typical capillary wick structure 41
Figure 28 Friction coefficients for laminar flow in trapezoidal ducts 43
Figure 29 Friction coefficients for laminar flow in circular segment ducts 43
Figure 30 Therma-Base™ heat sinks (Thermacore, Inc.) 48
Figure 31 Vapor Chamber products (Fujikura Ltd.) 48
Figure 32 Nanospreader™ (Celsia Technologies Inc.) 48
Figure 33 Liquid ChamberR (Vapro Inc.) 49
Figure 34 Tail-free vapor chamber (Acmecools Electronic Technology Inc.) 49
Figure 35 Vapor Chamber products (Taiwan Microloops Corp.) 49
Figure 36 Vapor SpreaderTM Foretherma Advanced Technology Co. Ltd. 50
Figure 37 Amec thermasol flat cool pipes 50
Figure 38 VCHS used on a Server system 51
Figure 39 VCHS used on a graphics processing unit (GPU) 51
Figure 40 Simulaion of multiple LEDs cooling solution 52
Figure 41 Complex vapor chamber communication devices 53
Figure 42 The assembly of the flat plate heat pipe 54
Figure 43 The top and bottom measurement points of the VCHS and heater 56
Figure 44 Cooling plate measurement points of the VCHS 57
Figure 45 The measurement points of the vapor chamber 58
Figure 46 Temperature and power density versus time diagram on 0.5 kg/cm2 and 30 C cooling water 59
Figure 47 Temperature and power density versus time diagram on 0.5 kg/cm2 and 40 C cooling water 60
Figure 48 Temperature and power density versus time diagram on 1.26 kg/cm2 and 30 C cooling water 60
Figure 49 Temperature and power density versus time diagram on 1.26 kg/cm2 and 40 C cooling water 61
Figure 50 Heat gain from electrical power 61
Figure 51 Thermal resistances versus time diagram of the VCHS on 0.5 kg/cm2 and 30 C cooling water. 63
Figure 52 Thermal resistances versus time diagram of the VCHS on 0.5 kg/cm2 and 40 C cooling water. 63
Figure 53 Thermal resistances versus time diagram of the VCHS on 1.26 kg/cm2 and 30 C cooling water. 64
Figure 54 Thermal resistances versus time diagram of the VCHS on 1.26 kg/cm2 and 40 C cooling water. 64
Figure 55 Comparison of the heat transfer rate of the VCHS 65
Figure 56 The orientation testing apparatus 66
Figure 57 The total resistance of different angle 67
Figure 58 Heat transfer rate change with different angle 68
Figure 59 Heat transfer rate on steady state region from 33 W to 35 W 68
Figure 60 Traditional heat pipe against gravity figure 70
Figure 61 The schematic of VCHS in 0, 90, and 180 degree position 70
Figure 62 Experimental apparatus of air and water cooling 71
Figure 63 Apparatus of the heating device 72
Figure 64 The maximum evaporator temperature as a function of time with different filling ratio (input power 73W, air cooling) 73
Figure 65 Thermal resistance with different filling ratio on 73 W input power 73
Figure 66 The maximum evaporator temperature trend from 20 to 262 W 74
Figure 67 Thermal resistance trend from 20 to 262 W 74
Figure 68 HP base cooling module 77
Figure 69 VCHS base cooling module unit for 12-Core 4 Chips Blade Server 78
Figure 70 Double size VCHS cooling module use for two CPU directly 78
Figure 71 The schematic of 4 chips blade server system 78
Figure 72 Temperature description and radar chat on 4 CPU chips 79
Figure 73 Multi level and complex vapor chamber heat spreader 80
Figure 74 The ICEPAK model for the special complex VCHS 80
Figure 75 The temperature description on heat sources and VCHS 81
Figure 76 The ICEPAK model for Intel 1366 CPU 82
Figure 77 Cross cut view of VCHS and copper base with 48 fins copper sink 84
Figure 78 Flow direction temperature description 84
Figure 79 Temperature description of VCHS and Copper Base with Cu fin 84
Figure 80 Heat Source Temperature by Copper base thermal module with various thickness aluminum and copper fins 87
Figure 81 Heat Source Temperature of VCHS base thermal module with various thickness aluminum and copper fins 87
Figure 82 Schematic of the thermal module setup 88
Figure 83 The ICEPAK model for BX924 CPU 88
Figure 84 Cross cut view of Copper Base and VCHS with sink at 95W 89
Figure 85 The temperature description with copper and VCHS base 89
Figure 86 Fan-less design on high power LEDs application 90
Figure 87 LED testing position diagram 91
Figure 88 LED apparatus and setup 91
Figure 89 Equivalent Heater Measure Position 92
Figure 90 The temperature trade on 4 LED chips by the distance change 93
Figure 91 (a) The pressure drop with various distance and (b) simulation results of LEDs array 93
Figure 92 Schematic of VCHS with radial grooved structure 95
Figure 93 Diffusion bonding results before polishing and after 95
Figure 94 The temperature change with the time by different filling rate 96
Figure 95 The Thermal resistance change with the time by different filling rate 96
Figure 96 Temperature variation in an internally heated conductor 102
Figure 97 Double heat sources in a plane wall temperature description 102
Figure 98 Conduction in a wall with uniform heat generation 103
Figure 99 Temperature distribution of two heater from center move to the side. 105
Figure 100 An evaporating region 106
Figure 101 PCR Cycler and PCR reaction mixtures 108
List of Tables
Table 1 Individual gas constants 31
Table 2 Different temperatures related to the equilibrium configuration 32
Table 3 Expressions for permeability and effective pore radius 42
Table 4 Wick permeability for several wick structure 43
Table 5 Temperature description with cooling temperature and pressure 59
Table 6 The average temperature and thermal resistance gradient with 50 W power and 40 °C cooling water. 69
Table 7 Copper and VCHS Base with 48 piece copper and aluminum fin 83
Table 8 The highest temperature of difference thermal modules with copper and VCHS base at various thickness and pieces of Fins 86
Table 9 Specification of the LED module(s)/array(s) 92
Table 10 The temperature distribution on different LED distance position 94
Table 11 The temperature distribution during Equivalent Heater 94
Table 12 The Correlation factor of different materials 94
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