陳炳煇臺灣大學：機械工程學研究所Uppala, RameshRameshUppala2007-11-282018-06-282007-11-282018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/61277This study aims to flow visualization and thermal analysis of a closed loop pulsating heat pipe based on inclination angle, charging ratio, type of fluid and heat flux for thermal control of micro electronic equipments. Although a variety of designs are in use, understanding of the fundamental processes and parameters affecting the PHP operation are still vague. A vertical, closed loop, glass PHP with water, methanol and 2-propanol as working fluids is first experimentally investigated for a range of heat inputs, inclination angles and charging ratios. Experimental studies are performed on a PHP, consisting of a heating section, an adiabatic section and a condensation section incorporating heat sink. The capillary tube used in this study has an inside diameter of 2mm and a wall thickness of 3mm.Total length of the pulsating heat pipe is 350cm. The experiments are conducted under forced convection cooling at the condenser section, with heating powers from 10 to 110W, with different heating modes (locations) and charging ratios from 30% to 80%. The experimental results show that the system presented better performance when operating at vertical orientation. Optimal charging ratio is 50% for DI water, 40% for methanol and 40% for 2-propanol. Regarding working fluid the PHP shows better performance when Methanol is used in vertical orientation with the lowest evaporator section temperatures.Table of Contents Acknowledgement I Abstract II Table of Contents IV List of Tables VI List of Figures VII Chapter 1: Introduction 1 1.1 General remarks 1 1.2 History of heat pipe 2 1.3 Drawbacks in heat pipe 5 1.4 Motivation of pulsating heat pipe 6 1.5 Present study 8 1.6 Thesis organization 9 Chapter 2: Working Principle 10 Chapter 3: Experimental Setup 12 3.1 General discussion 12 3.2 Experimental apparatus 12 3.3 Experimental procedure 14 Chapter 4: Results and Analysis 16 4.1 Effect of charging ratio on thermal performance of PHP 16 4.2 Effect of thermal conductance on thermal performance of PHP 18 4.3 Effect of evaporator temperature on thermal performance of PHP 19 4.4 Effect of obliquity on thermal performance of PHP 20 4.5 Effect of heating mode on thermal performance of PHP 21 4.6 Operational possibilities of PHP 22 4.7 Possibilities of geyser boiling in PHP 22 Chapter 5: Conclusions and Future Prospects 26 References 58 List of Tables Index 28 Table 4.1 29 Vertical orientation Table 4.2 29 Horizontal orientation Table 4.3 30 450 degrees orientation Table 4.4 31 The ranges of heat load to the evaporator for occurrence of the geyser boiling in a water-filled PHP with lh=5cm Table 4.5 31 The ranges of heat load to the evaporator for occurrence of the geyser boiling in a water-filled thermosyphon with lh=14cm List of Figures Figure 3.1 32 Prototype of present experimental study Figure 3.2 33 Experimental setup for closed loop pulsating heat pipe Figure 3.3 34 -35 (a) Data acquisition system, (b) AC power supply, and (c) DC power supply Figure 4.1 36 Effect of water charging ratio on thermal resistance of PHP Figure 4.2 37 Effect of methanol charging ratio on thermal resistance of PHP Figure 4.3 38 Effect of 2-propanol charging ratio on thermal resistance of PHP Figure 4.4 39 Effect of water charging ratio on thermal resistance of PHP Figure 4.5 40 Effect of methanol charging ratio on thermal resistance of PHP Figure 4.6 41 Effect of 2-propanol charging ratio on thermal resistance of PHP Figure 4.7 42 Thermal conductance for DI water charging ratio in vertical orientation Figure 4.8 43 Thermal conductance for Methanol charging ratio in vertical orientation Figure 4.9 44 Thermal conductance for 2-propanol charging ratio in vertical orientation Figure 4.10 45 Effect of heat input on evaporator temperature for DI water charging ratio in vertical orientation Figure 4.11 46 Effect of heat input on evaporator temperature for Methanol charging ratio in vertical orientation Figure 4.12 47 Effect of heat input on evaporator temperature for 2-propanol charging ratio in vertical orientation Figure 4.13 48 Evaporator temperature comparison between three working fluids in vertical orientation Figure 4.14 49 Thermal performance vs. inclination angle for DI water with 60% charging ratio Figure 4.15 50 Effect of heating mode in vertical orientation for 50% charging ratio Figure 4.16 51 Effect of heating mode in 450 orientations for 50% charging ratio Figure 4.17 52 Temperature versus Time under VBH for 10W of heat input Figure 4.18 52 Temperature versus Time under VBH for 10W of heat input Figure 4.19 53 Temperature versus Time under VBH for 20W of heat input Figure 4.20 53 Temperature versus Time under VBH for 20W of heat input Figure 4.21 54 Temperature versus Time under VBH for 40W of heat input Figure 4.22 54 Temperature versus Time under VBH for 40W of heat input Figure 4.23 55 Temperature versus Time under VBH for 50W of heat input Figure 4.24 55 Temperature versus Time under VBH for 50W of heat input Figure 4.25 56 Temperature versus Time under VBH for 110W of heat input Figure 4.26 56 Temperature versus Time under VBH for 110W of heat input Figure 4.26 57 Schematic diagram of the test section from [Lin, 1995]938055 bytesapplication/pdfen-US脈衝熱管兩相流電子散熱流場分析Pulsating heat pipeTwo-phase loopElectronic coolingFlow patternthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/61277/1/ntu-93-R92522122-1.pdf