The Measurement, Improvement, and Performance Prediction of Capillary Structure for a Thin Vapor Chamber

• Main Authors: Po-Sheng Chuang, 莊博盛
• Other Authors: 朱錦洲
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/5f7z99

碩士 === 國立臺灣大學 === 應用力學研究所 === 105 === Currently the overall thickness of a vapor chamber needs to be flattened to meet the design space of a mobile phone but the performance of a vapor chamber thus cannot be raised. This study puts an emphasis on measuring the performance of wick and determining to promote the performance of a thin vapor chamber. From analyzing maximum heat transfer capacity of vapor chamber, the maximum heat transfer rate of a thin vapor chamber is controlled by the capillary limitation of ultra-thin vapor chamber. The factor which can enhance the capillary performance is related to permeability, effective pore radius and wettability. This study, with the help of Professor Chien-Cheng Cahng’s theory, designs different copper mesh wicks(54*104*0.1 mm3). By capillary rise, we can measure capillary height and capillary mass. The quantity index of wick is as follows. Evaporating section(15*15 mm2), Condensing section(30*50 mm2). The study shows that when the width of groove is less than 1.80 mm, the groove area will contain working fluid, turning wick from biporous structure to mono-porous structure. Compared with Kw/reff of Copper_Mesh_#1_1(0.305 μm), Groove_with_water_#4_1(0.644 μm) can improve the capillary performance by 52%. Compared with maximum heat transfer capacity of Copper_Mesh_#1_1(3.94 W), Groove_with_water_#4_1 (7.56 W) can improve the capillary performance by 30%. This study appears that the structure of groove can effectively enhance the capillary performance since it can provide extra capillary force, as well as raise the permeability to reduce the working fluid resistance, and therefore better the overall performance.