鐵氟龍毛細結構應用於平板型迴路式熱管之研究

The Study of PTFE Wick Structure Applied to Flat Plate Loop Heat Pipe

黃承緯(Cheng-Wei Huang)

指導教授 ： 陳瑤明

國立臺灣大學/工學院/機械工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601730

摘要

迴路式熱管為一種具相變化的被動熱傳裝置，相較於傳統熱管，其優點有：遠距熱傳輸、低熱阻與高熱傳量等。影響迴路式熱管表現的關鍵在於毛細結構。鎳因其具有多樣化工質的相容性和較低的熱傳導係數，普遍運用在現今的迴路式熱管，取代傳統的銅毛細結構。近年電子元件功率密度提高，單位密度所需處理的熱逐漸上升，造成金屬毛細結構難以抵擋熱洩漏的問題，尋找熱傳導係數更低的毛細結構為新的研究課題。非金屬的鐵氟龍(PTFE)毛細結構，具有更低的熱傳導係數和良好的可塑性，近年有日本學者[20]嘗試應用至迴路式熱管。
本研究嘗試設計並建立氣冷平板型迴路式熱管應用於熱電晶片上，熱電晶片目標散熱瓦數為85W，操作溫度需低於100℃，熱阻要小於0.5K/W，並有傳輸距離上的限制。藉由熱傳性能測試改善冷凝段長度、鰭片之設計，並改變工作流體填充量、毛細結構，來尋找符合熱電晶片需求散熱瓦數的氣冷平板型迴路式熱管之設計，且達到低操作溫度、低熱阻的目標。
在實驗方面，經計算與實驗測試發現，最適當的冷凝段長度為250mm，工作流體填充量為整體迴路式熱管體積的60%。於適當的參數下，以鐵氟龍毛細結構於氣冷平板型迴路式熱管中進行熱傳性能測試，在熱電晶片目標散熱瓦數85W下，其操作溫度達58℃，系統熱阻為0.38 K/W，補償室溫度為28℃。與金屬毛細結構比較，鎳和銅毛細結構在85W下操作溫度分別為75℃和79℃，熱阻為0.58K/W和0.63K/W，補償室溫度為39℃和45℃，鐵氟龍毛細結構皆有較好的熱傳性能。
總結本研究之成果，本研究成功建立氣冷平版型迴路式熱管，並使用鐵氟龍作為毛細結構，能有效的降低操作溫度和熱阻並成功的阻擋熱洩漏。與金屬毛細結構相比，有製程較為安全、製造成本較低、較好加工等優點，對於未來高功率元件的冷卻而言，鐵氟龍毛細結構有高度應用之潛力。

關鍵字

氣冷平板型迴路式熱管 ； 熱洩漏 ； 鐵氟龍

並列摘要

Loop heat pipe, compared to a conventional heat pipe, is a passive phase change, heat transfer device having the advantages of long-distance heat transfer, low thermal resistance and high heat transfer capacity etc. The key point of it is the wick structure.
Because of its wide-range compatibility of working fluid and low thermal conductivity coefficient, as a wick material, nickel can replace copper using in loop heat pipe nowadays. In recent years, the power density of electronic components rises with thermal processing required per unit density gradually increased, causing metal wick structures hard to resist heat leakage, which becomes a new researching issue. Non-metallic wick structure- Teflon (PTFE), has a low thermal conductivity coefficient and good plasticity, so Japanese scholars in recent years [20] attempts to apply PTFE to the loop-type heat pipe.
This study attempts to design and build air-cooling flat-plate loop heat pipe used in thermoelectric wafer with the target thermoelectric cooling wattage of 85W, operating temperature below 100℃ and the thermal resistance less than 0.5K/W. By the thermal performance test, this this study not only improve the condenser length and fin design, but also change the material of wick structure and the amount of working fluid filled in that, in order to find the proper air-cooling flat-plate loop heat pipe and achieve low operating temperature with low thermal resistance target.
Based on the result of experiments, after calculating and testing, it goes that it is the best cooling length of 250mm; the working fluid is filled 60% of the total volume of the loop heat pipe. Under these parameters, this study uses Teflon wick structure as heat-transfer-performance tests on air-cooling flat-plate loop heat pipe. With target wattage 85W, its operating temperature is of 58℃, the system thermal resistance of 0.38 K/W, the compensation chamber temperature of 28℃. Compared with the metal wick structure like nickel and copper at 85W, they have the operating temperatures of 75℃ and 79℃ separately, thermal resistance 0.58K/W and 0.63K/W, the compensation chamber temperature of 39℃ and 45℃.The Teflon wick structure has better heat transfer performance from above.
Summarize the results; this study successfully established air-cooling flat-plate loop heat pipe, and using Teflon as wick structures, which effectively reduce the operating temperature and the thermal resistance without heat leakage. Compared to metal wick structures, Teflon wick structures have lower manufacturing costs, better processing, etc. Moreover, the Teflon wick structures have high potential of high-power cooling element in the future.

並列關鍵字

air-cooled flat-plate loop heat pipe ； heat leakage ； Teflon

參考文獻

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