薄扁平型可撓熱管之熱傳性能研究

Experimental Investigation on the Thermal Performance of Flat Thin Flexible Heat Pipe

吳彥霆(Yen-Ting Wu)

指導教授 ： 陳炳煇

國立臺灣大學/工學院/機械工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003415

摘要

本研究欲研發一薄扁型可撓式熱管並對其熱傳效能進行量測和最佳化。此一可撓式熱管之外殼是利用可熱壓封裝的鋁箔高分子複合膜製成。其氣體通道由一雙層粗銅網(#40)構成，而毛細結構則由一經複合式超親水改質的細銅網製成。此一複合式超親水改質法是先以氧化銅法再以溶膠凝膠法處理，銅網表面先以氧化法處理形成一層氧化銅的氧化層，接著再進行溶膠凝膠法以鍍上二氧化矽奈米粒子。此一可撓式熱管之有效區域為一長70 mm，寬20 mm之長方型區域，其厚度為2 mm。在本研究中就諸多熱管製程和性能參數被逐一研究和討論，例如:毛細結構改質前後比較、氣體通道之結構設計、工作流體填充量、操作時之彎曲角度以及熱管壽命。最終實驗結果顯示，此一可撓式熱管若安裝經複合式改質後的毛細結構以及雙層銅網氣體通道，其熱阻值會有非常顯著的下降。在填充量方面則是發現在0.5 g的填充量時，可撓式熱管將有最低的熱阻值。另外，研究發現熱管在彎曲狀態下操作時，其熱阻值會微幅上升。然而，若彎曲時將冷凝端提至高於蒸發端的位置時，重力會輔助液體回流至蒸發端使之效能提升，故其即使在大角度彎曲下仍能有更低於水平操作時之熱阻值。最後，研究發現此一可撓式熱管約有100小時的操作壽命，其最終將因大氣由熱壓封裝接合處緩慢滲入其內部而導致失效。

關鍵字

扁平型可撓式熱管 ； 熱阻值 ； 鋁箔高分子複合袋 ； 銅網 ； 表面改質 ； 超親水性 ； 彎曲 ； 填充 ； 壽命

並列摘要

In this study, a flexible flat thin heat pipe was fabricated and its thermal performance was experimentally investigated. The casing of the flexible heat pipe was made out of heat-sealable aluminum polymer composite package. The vapor core of the heat pipe was made out of coarse copper mesh (#40), and the capillary wick was made out of fine copper mesh (#200) treated with a hybrid superhydrophilic surface modification method. The hybrid surface modification method was a combination of oxidation method and sol-gel method. This method would create CuO layers on the wick first, and was later coated with SiO_2 nano-particles. The flexible heat pipe had an effective area of 70 mm in length, 20 mm in width, and 2 mm in thickness. Factors such as the treatment on capillary wick, vapor core structural designs, filling amount of working fluid, bending angles, and lifespan of the heat pipe were investigated in this study. The results indicated that flexible heat pipes with modified wick and double layered vapor core had a significant decrease in thermal resistance. The filling amount was recommended to be 0.5 gw, which had the lowest thermal resistance. Besides, heat pipes operating under bending angles had slightly larger thermal resistance. However, if it was oriented with condenser section at a higher level, the gravity would assist the liquid flow resulting in lower thermal resistance even under bending conditions. Finally, the flexible heat pipe had a lifespan around 100 hours before it lost its performance due to the permeation of the air through the bonding region of the heat pipe.

並列關鍵字

flexible flat thin heat pipe ； thermal resistance ； aluminum polymer package ； copper mesh ； surface modifications ； superhydrophilic ； bending ； filling ； lifespan

參考文獻

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