[[alternative]]鋁質蒸汽腔體均熱片之製造與分析

博士[[abstract]]本研究主要是針對鋁質蒸汽腔體均熱片之製造與分析，文中分為鋁質蒸汽腔體的實驗分析與二相流分析應用於蒸汽腔體。蒸汽腔體外觀尺寸58mmx58mmx6mm，使用鋁合金6061作為材料，毛細結構採用向中心傾斜的放射狀溝槽以及鋁粉燒結結構兩種設計。溝槽的尺寸分別是寬度0.4mm與深度0.65-0.91mm；鋁粉燒結毛細結構孔隙率為0.32，厚度為0.5mm，並設計八支直徑3mm燒結柱。工作流體採用丙酮充填兩種鋁質蒸汽腔體。 在鋁質蒸汽腔體的研究部分，實驗測試包含最佳充填量、隨著功率變化的整體熱阻值、以及散熱端表面溫度的量測。結果顯示放射狀溝槽式鋁質蒸汽腔體最佳充填率為25%，並藉由表面溫度的結果得知溝槽毛細結構可提升整體熱傳性能的特性。燒結式鋁質蒸汽腔體最佳充填率為55%；隨著功率的變動，整體熱阻值的變動(0.65-0.69℃/W)小於溝槽式的設計(0.72-0.91℃/W)。 本文第二部份為探討二相流分析應用於蒸汽腔體的研究。運算分析使用計算流體力學模擬軟體Fluent中的多相流模組-VOF來研究工作流體於蒸汽腔體中的作動情形。文中利用汽液相、溫度與速度分佈圖來進行分析與研究。蒸汽腔體尺寸比照文獻設計為46.5mmx4.6mm的二維軸對稱模型。結果探討包含啟動機制與達到穩態的工作流體汽相、液相、溫度場、速度場運作過程。另針對毛細結構支柱與多點熱源作模擬分析。 模擬分析比對文獻實驗數據與數值分析，結果顯示蒸汽腔體底部中心溫度略高於實驗與數值分析，與實驗數據僅差距1℃。並藉由啟動至穩態的模擬分析，探討工作流體汽相、液相、溫度場與速度場變化的現象。隨著功率的輸入，工作流體逐漸產生相變化傳熱機制，並生成汽泡、蒸汽膜。文中並探討毛細支柱的設計與多熱源的關係。透過模擬的結果顯示出，理想的狀況之下，毛細支柱的設計與否，對於蒸汽腔體熱傳效率影響並不明顯。[[abstract]]This study presents the fabrication and analysis of aluminum vapor chamber heat spreaders. It is divided into two main topics, fabrication and experiment of aluminum vapor chamber and the two-phase flow analysis inside the vapor chamber, respectively. Aluminum alloy 6061 as the container material is used to fabricate the aluminum vapor chamber with the radial grooved wick and sintered aluminum powders wick. Two kinds of aluminum vapor chambers are of the same dimension of 58mmx58mmx6mm. For radial grooved aluminum vapor chamber, the groove is dimension 0.4mm wide and 0.65-0.91mm deep due to an arc design and the radius of central pool is 10.16mm. For sintered aluminum powders vapor chamber, the sintered wick is 0.5mm thick and eight pillars with diameter of 3mm are inserted inside it. The porosity is 0.32. The working fluid is acetone charged with all aluminum vapor chambers. The results of all aluminum vapor chambers present the optimum charging amounts of the working fluid and the overall thermal resistance with heat input power 20-80W in increment of 20W, as well as the temperature at the bottom of heat sink. According to measuring the charging amounts of the working fluid, the fill ratios of grooved and sintered vapor chamber are 25%(1.02g) and 55%(2.69g) respectively. These results show that the radial grooved wick structures enhance the heat transfer coefficient of vapor chamber due to heat conduction and phase change. Compared with two kinds of wick designs, the overall thermal resistance of sintered aluminum powders vapor chamber (0.65-0.69℃/W) is changed and less than one of radial grooved vapor chamber (0.72-0.91℃/W) after steady state with heat input power 20-80W in increments of 20W. The second topic of this study is the two-phase flow analysis inside the vapor chamber. The two-phase flow analysis is done by Volume of Fluid (VOF) multi-flow method of CFD simulation software Fluent. The simulation model of vapor chamber is axisymmetrically two-dimensional model of 46.5mmx4.6mm followed Y. Koito’s literatures. The start-up operation of vapor chamber for the two-phase flow analysis and three kinds of Types for vapor chamber subjected to multiple discrete heat sources and effect of pillar design are discussed. The phase, temperature, velocity distributions are investigated. The temperature at the center of the bottom of the vapor chamber for simulation result is in good agreement with the experimental and numerical of literature result, although the temperature of numerical result is slightly lower than simulation result. The start-up operation of vapor chamber is illustrated and discussed until steady state or dry out by the phase, temperature, and velocity distribution. With heat input power, the liquid phase is transferred to the vapor phase, and the bubbles or vapor films are formed. The phase change causes the significant temperature difference. The bubble growing leads to the velocity vortex. The velocity at the wick region is slighter than it at the vapor core. Vapor chamber with pillar design and subjected to multiple discrete heat sources are simulated and discussed with respect to different the phase, temperature, and velocity distribution. From simulation results, the top surface temperature distributions at the top wall with pillar design are somewhat the same as the temperature field with none pillar design. The pillar design does not affect the heat transfer efficiency of vapor chamber for ideal heat transfer of phase change.[[tableofcontents]]Contents Acknowledgments…………………………………………………. I Chinese Abstract…………………………………………………... II English Abstract…………………………………………………… IV List of Contents……………………………………………………. VI List of Figures……………………………………………………… X List of Tables……………………………………………………….. XVIII Nomenclature……………………………………………………… XIX Chapter 1 Introduction…………………………………………. 1 1.1 Background………………………………………………………….. 1 1.2 Literature Review……………………………………………………. 2 1.3 Motivation…………………………………………………………… 5 Chapter 2 Aluminum Vapor Chamber with Radial Grooved Wick Structures……………………………………... 7 2.1 Introduction of Aluminum and Aluminum Alloy……………..……... 7 2.2 Design and Experiment……………………..……………………….. 10 2.2.1 Introduction of Radial Grooves…………………………………... 10 2.2.2 Design of Aluminum Vapor Chamber with Radial Grooved Wick…………………………………………………………........ 11 2.2.3 Experimental Setup and Procedure…………………………......... 13 2.3 Results and Discussion………………………………………………. 16 2.3.1 Effect of Charging Amounts of the Working Fluid…………......... 17 2.3.2 Effect of Temperatures at the Bottom of the Heat Sink………….. 20 2.4 Preliminary Conclusion……………………………………………… 23 Chapter 3 Aluminum Vapor Chamber with Sintered Aluminum Powders Wick Structures……………… 25 3.1 Introduction………………………………………………………….. 25 3.2 Sintered Powders Wick Structure……………………………………. 29 3.3 Design and Experiment……..……………………………………….. 31 3.3.1 Introduction of Aluminum Powder Application………………….. 31 3.3.2 Strain Analysis of Vapor Chamber with and without Pillars……... 31 3.3.2.1 Deformation of Vapor Chamber……………………………... 35 3.3.2.2 Finite Element Model and Boundary Conditions…………… 36 3.3.2.3 Thermal Analysis of Vapor Chamber………………………... 40 3.3.2.4 Conclusion of Strain Analysis of Vapor Chamber…………... 49 3.3.3 Design of Aluminum Vapor Chamber with Sintered Aluminum Powders Wick Structures………………………………………… 50 3.3.4 Porosity Measurement Experimental Procedure……………...….. 52 3.4 Results and Discussions……………………………………………... 54 3.4.1 Effect of Porosity of Sintered Aluminum Powders………………. 54 3.4.2 Effect of Charging Amounts of the Working Fluid………………. 56 3.4.3 Effect of Temperatures at the Bottom of the Heat Sink………….. 59 3.5 Preliminary Conclusion……………………………………………… 61 Chapter 4 Two Phase Flow Analysis of Vapor Chamber Heat Spreaders……………………………………………. 63 4.1 Introduction to Analysis of Vapor Chamber…………………………. 63 4.2 Simulation Analysis of Vapor Chamber……………………………... 79 4.2.1 CFD Simulation Model of Vapor Chamber……………………… 79 4.2.2 Introduction and Basic Theory of Fluent………………………… 84 4.2.3 Introduction and Theory of Volume of Fluid (VOF)……………... 90 4.2.4 Boundary Condition……………………………………………… 94 4.3 Numerical Simulation Results and Discussions……………………... 97 4.3.1 Comparison of Single- and Two-Phase Flow Analysis…………. 97 4.3.2 Start-Up Operation of Vapor Chamber………………………….. 100 4.3.3 Effect of Variation of Heat Input to the Multiple Heat Sources… 106 4.3.3.1 Effect of Type II and Type IV to the Two Heat Sources…….. 106 4.3.3.1.1 Start-Up Operation of Type II to the Two Heat Sources….. 106 4.3.3.1.2 Start-Up Operation of Type IV to the Two Heat Sources… 112 4.3.3.2 Effect of Type III and Type IV to the Three Heat Sources…... 116 4.3.3.2.1 Start-Up Operation of Type III to the Three Heat Sources.. 116 4.3.3.2.2 Start-Up Operation of Type IV to the Three Heat Sources.. 122 4.3.3.3 Comparison of Three Types to the Multiple Discrete Heat Sources………………………………………………………. 125 4.4 Preliminary Conclusion……………………………………………… 127 Chapter 5 Summary…………………………………………….. 128 5.1 Summary…………………………………………………………….. 128 5.2 Conclusion…………………………………………………………... 129 5.3 Future Work………………………………………………………….. 130 Reference…………………………………………………………… 134 Appendix A Uncertainty Analysis……………………………… 140 Appendix B Experimental Data of Aluminum Vapor Chamber with Radial Grooved Wick Structures.. 141 Appendix C Experimental Data of Aluminum Vapor Chamber with Sintered Aluminum Powders Wick Structures…………………………………… 142 Appendix D Material Property of Simulation Analysis………. 143 Appendix E User-Defined Function Source Code…………….. 144 Publication List ……………………………………………………… 146 List of Figures Figure 1-1 Illustration of vapor chamber………………………………….. 2 Figure 1-2 Roll bonding fabrication process……………............................. 4 Figure 1-3 Schematic and design of an arch-shaped channel……………... 5 Figure 1-4 The heat spreaders with network design of wicks……………... 5 Figure 2-1 The radial grooved micro heat pipe heat spreaders: (a) A three-layer silicon structure. (b) Three copper foil layers……... 11 Figure 2-2 Schematic of the radial grooved vapor chamber………………. 12 Figure 2-3 Photograph of the radial grooved vapor chamber……………... 12 Figure 2-4 A scheme of experimental apparatus of CPU cooler…………... 15 Figure 2-5 Measuring the temperatures at the bottom of the heat sink……. 15 Figure 2-6 Schematic of the experimental apparatus……………………… 16 Figure 2-7 Comparison of charging amounts of acetone and thermal resistance of the aluminum vapor chamber with radial grooved wick structures…………………………………………………. 18 Figure 2-8 Comparison of thermal resistance and filling ratios of acetone for aluminum vapor chamber with radial grooved wick structures……………………………………………………….. 19 Figure 2-9 Comparison of temperature difference (Tc-Ta) and filling ratios of acetone for aluminum vapor chamber with radial grooved wick structures…………………………………………………. 19 Figure 2-10 Distributions of the contact temperature, ambient temperature, and overall thermal resistance at the charging amount of 1.02g (filling ratio of 25%) with time for aluminum radial grooved vapor chamber…………………………………………………. 20 Figure 2-11 Distributions of the temperatures at the bottom of heat sink with time for the aluminum radial grooved vapor chamber…… 21 Figure 2-12 Distributions of the temperatures at the bottom of heat sink with position…………………………………………………… 22 Figure 2-13 Schematic of the vapor flow and heat paths on the condensation surface…………………………………………… 22 Figure 2-14 Comparison of the contact temperature and temperatures at the bottom of heat sink with heat input power…………………….. 23 Figure 3-1 (a) Effect of powder diameter and wick thickness on the heat transfer rate. (b) Effect of porosity on the heat transfer rate…... 30 Figure 3-2 Typical aluminum powder metallurgy parts…………………… 31 Figure 3-3 Deformation of vapor chamber………………………………... 34 Figure 3-4 Deformation of vapor chamber after welding…………………. 36 Figure 3-5 Dimension of vapor chamber for strain analysis………………. 36 Figure 3-6 Symmetrically quartered finite element model………………... 38 Figure 3-7 Case I for heater size of 14x14mm2…………………………… 38 Figure 3-8 Case I for heater size of 30x30mm2…………………………… 39 Figure 3-9 Case II for heater size of 14x14mm2…………………………... 39 Figure 3-10 Case II for heater size of 30x30mm2…………………………... 39 Figure 3-11 The stress distribution of vapor chamber with a pillar of Case I distance from the center of mm for heater size of 14x14mm2……………………………………………………… 41 Figure 3-12 The stress distribution of vapor chamber without a pillar distance from the center of mm for heater size of 14x14mm2…………………………………………………........ 41 Figure 3-13 Strains of vapor chamber on the x-directional line and diagonal………………………………………………………... 42 Figure 3-14 Strain distributions of Case I along x-directional line for heater size 14x14mm2………………………………………………… 42 Figure 3-15 Strain distributions of Case I along x-direction for heater size 30x30mm2……………………………………………………… 42 Figure 3-16 Strain distributions of Case I along a diagonal for heater size 14x14mm2……………………………………………………… 43 Figure 3-17 Strain distributions of Case I along a diagonal for heater size 30x30mm2……………………………………………………… 43 Figure 3-18 Stress distribution with pillars of Case II distance from the center of mm for heater size of 14x14mm2……………………………………………………… 44 Figure 3-19 Strain distributions of Case II along x-directional line for heater size 14x14mm2………………………………………… 44 Figure 3-20 Strain distributions Case II along x-directional line for heater size 30x30mm2.………………………………………………... 45 Figure 3-21 Strain distributions Case II along a diagonal for heater size 14x14mm2…………………………………………………….... 45 Figure 3-22 Strain distributions Case II along a diagonal for heater size 30x30mm2……………………………………………………… 45 Figure 3-23 The average of strains along the x-directional line and diagonal within the heater area of 14x14mm2 and vapor core for Case I.. 47 Figure 3-24 The average of strains along the x-directional line and diagonal within the heater area of 30x30mm2 and vapor core for Case I.. 47 Figure 3-25 The average of strains along the x-directional line and diagonal within the heater area of 14x14mm2 and vapor core for Case II. 48 Figure 3-26 The average of strains along the x-directional line and diagonal within the heater area of 30x30mm2 and vapor core for Case II. 48 Figure 3-27 Effect of wall thickness on strain of vapor chamber…………... 48 Figure 3-28 (a) Dimension of the bottom and top aluminum plates. (b) Dimension of the sintered aluminum powders wicks. (c) Combination of plates, wicks, and a feeding tube and Photograph of the sintered aluminum powder vapor chamber… 52 Figure 3-29 Porosity measurement apparatus………………………………. 53 Figure 3-30 The sample of sintered aluminum powders……………………. 55 Figure 3-31 SEM photographs of sintered aluminum powders of samples (a) on the pillar (zoom = 500X). (b) on the pillar (zoom = 1000X). (c) on the surface (zoom = 500X). (d) on the surface (zoom = 1000X). 55 Figure 3-32 Comparison of charging amounts of acetone and thermal resistance of the aluminum vapor chamber with sintered aluminum powers wick structures……………………………... 57 Figure 3-33 Comparison of thermal resistance and filling ratios of acetone for aluminum vapor chamber with sintered aluminum powers wick structures…………………………………………………. 57 Figure 3-34 Comparison of temperature difference (Tc-Ta) and filling ratios of acetone for aluminum vapor chamber with sintered aluminum powers wick structures……………………………... 58 Figure 3-35 Distributions of the contact temperature, ambient temperature, and overall thermal resistance at the charging amount of 2.69g (filling ratio of 55%) with time for vapor chamber with sintered aluminum powers wick structures…………………….. 58 Figure 3-36 Distributions of the temperatures at the bottom of heat sink with time for the aluminum vapor chamber with sintered aluminum powers wick structures……………………………... 60 Figure 3-37 Distributions of the temperatures at the bottom of heat sink with position…………………………..……………………….. 60 Figure 3-38 Comparison of the thermal resistances of aluminum vapor chamber with radial grooves and sintered aluminum powders wicks with heat input power.…………………………………... 61 Figure 4-1 The numerical model of transient analysis for heat pipe………. 71 Figure 4-2 The numerical model of the frozen state analysis for heat pipe.. 71 Figure 4-3 A network system for the heat pipe operation. (a) A sketch of the heat pipe heat transfer. (b) A network analogy of the heat pipe heat transfer……………………………………………….. 72 Figure 4-4 Schematic of (a) the disk-shaped heat pipe. (b) the flat-plate heat pipe………………………………………………………... 73 Figure 4-5 A schematic illustration of the flat plate heat pipe under three typical geometries and locations of the heat zone……………... 73 Figure 4-6 Pressure contours and the flow velocity fields to three typical heaters………………………………………………………….. 74 Figure 4-7 Schematic numerical model of vapor chamber………………... 75 Figure 4-8 Temperature distributions in silicon vapor chamber…………... 75 Figure 4-9 (a) Flip chip package with traditional copper IHS (integral heat spreader) and silicon vapor chamber. (b) Comparison on die stresses with copper IHS and vapor chamber………………….. 76 Figure 4-10 Mathematical model of the vapor chamber by H. Imura et al…. 76 Figure 4-11 Temperature distribution inside the vapor chamber…………… 77 Figure 4-12 Comparison between the numerical results and experimental results for Y. Koito’s…………………………………….……... 77 Figure 4-13 Physical model and liquid film distribution model……………. 78 Figure 4-14 Temperature distribution of the vapor chamber………………... 78 Figure 4-15 Liquid film thickness distribution in the groove at different heat fluxes……………………………………………………… 78 Figure 4-16 Schematic of the mesh model………………………………….. 80 Figure 4-17 Schematic and parameters of simulation model Type I………... 81 Figure 4-18 Schematic and parameters of simulation model Type II.…......... 82 Figure 4-19 Schematic and parameters of simulation model Type III……… 82 Figure 4-20 Schematic and parameters of simulation model Type IV for multiple discrete heat sources.…………………………………. 83 Figure 4-21 The flowchart of solution……………………………………… 90 Figure 4-22 The free surface among the computational cells by VOF method…………………………………………………………. 93 Figure 4-23 The mass and energy jump conditions in the interface between vapor phase and liquid phase…………………………………... 93 Figure 4-24 Vapor bubbles periodically form (red) along a heater surface and rise through the liquid (yellow)……………………………. 94 Figure 4-25 Vapor forms in the wick………………………………………... 97 Figure 4-26 Effect of the simulation result on the (a) temperature distribution and (b) velocity vector inside the vapor chamber.……………………………………………..…………. 99 Figure 4-27 Figure. 4-27 Effect of the numerical result on the (a) temperature distribution and (b) velocity vector inside the vapor chamber…………………………………………………. 99 Figure 4-28 Phase distribution inside the vapor chamber…………………... 103 Figure 4-29 Temperature distribution inside the vapor chamber…………… 104 Figure 4-30 Distribution of velocity vector inside the vapor chamber……... 106 Figure 4-31 Phase distribution inside the Type II vapor chamber…………... 109 Figure 4-32 Temperature distribution inside the Type II vapor chamber…… 110 Figure 4-33 Distribution of velocity vector inside the Type II vapor chamber………………………………………………………... 112 Figure 4-34 Phase distribution inside the Type IV for two heat sources……. 114 Figure 4-35 Temperature distribution inside the Type IV for two heat sources…………………………………………………………. 115 Figure 4-36 Distribution of velocity vector inside the Type IV for two heat sources…………………………………………………………. 115 Figure 4-37 Phase distribution inside the Type III vapor chamber…………. 119 Figure 4-38 Temperature distribution inside the Type III vapor chamber….. 120 Figure 4-39 Distribution of velocity vector inside the Type III vapor chamber………………………………………………………... 122 Figure 4-40 Phase distribution inside the Type IV for three heat sources…... 123 Figure 4-41 Temperature distribution inside the Type IV for three heat sources…………………………………………………………. 124 Figure 4-42 Distribution of velocity vector inside the Type IV for three heat sources…………………………………………………………. 125 Figure 4-43 Comparison of the top surface temperature distribution of Type II and Type IV at the top wall………………………………….. 126 Figure 4-44 Comparison of the top surface temperature distribution of Type III and Type IV at the top wall…………………………………. 126 Figure 5-1 Schematic of composed wick and the liquid/vapor flow paths... 131 Figure 5-2 Scheme of the simulation model in the evaporator……………. 133 Figure 5-3 Scheme of the simulation model in the condenser…………….. 133 List of Tables Table 1-1 Material compatibility for container and fluid combinations…..... 4 Table 3-1 Typical wick designs…………………………………………….. 28 Table 3-2 The physical property of copper for strain analysis simulation…. 38 Table 3-3 Occupation area of pillar and strain decrease……………………. 49 Table 3-4 The physical property of aluminum……………………………... 49 Table 4-1 The geometric parameters of the vapor chamber………………... 81 Table 4-2 The boundary conditions in the heat sources……………………. 97 Table 4-3 Comparison of the simulation, numerical, and experimental results at the center of the bottom of the vapor chamber………... 98[[note]]學號: 894340057, 學年度: 9