具毛細結構與泵複合式平板型迴路式熱管之研究

The Study of Wick Structure and Pump-Assisted for Hybrid Flat Plate Loop Heat Pipe

曾紹琦(Shao-Chi Tseng)

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/NTU201601729

摘要

迴路式熱管具相變化功能、熱通量高、傳輸距離遠、熱阻小等優點。為使迴路式熱管熱傳性能提升以因應密集的能源使用，如核能發電廠、電子晶片模組等高功率密度的散熱需求，本研究擬開發適用於高功率密度(>100 W/cm2)平板型迴路式熱管散熱系統，採用整合毛細結構與泵的混合式驅動概念，建立複合式平板型迴路式熱管散熱系統。探討泵在流量變化(0.3 L/min~1.5 L/min)對複合式平板型迴路式熱管的熱傳現象，並使用鎳與鐵氟龍作為毛細結構評估熱洩漏的影響。
複合式平板型迴路式熱管以鎳作為毛細結構並搭配純水，在泵流量0.6L/min時，最大熱傳量可達1200W (熱通量為 153.1 W/cm2)最低總熱阻值為 0.09 ℃/W。在流量效應上最佳流量會有最低總熱阻值，對鎳和鐵氟龍毛細結構分別是0.9L/min和1.2L/min，在最佳流量下且壁面溫度100℃限制並以丙酮作為工質，鎳毛細結構最大熱傳量700W(熱通量為 89.3W/cm2)和最低總熱阻值0.07℃/W；鐵氟龍毛細結構最大熱傳量900W(熱通量為 114.8W/cm2)和最低總熱阻值0.04℃/W。鐵氟龍較鎳毛細結構在最大熱傳量上提升近30%，最低總熱阻值減少42.9%。在電子冷卻蒸發器壁面容許溫度85℃下，鎳毛細結構最大熱傳量500W (熱通量為 63.8W/cm2)，而最低總熱阻值為 0.07℃/W；鐵氟龍毛細結構最大熱傳量800W (熱通量為 102.9W/cm2)而最低總熱阻為 0.04℃/W。鐵氟龍毛細結構較鎳毛細構提升60%，最低熱阻減少42.9%。實驗發現熱洩漏對複合式平板型迴路式熱管熱傳性能影響不明顯，而由水銀測孔發現鐵氟龍毛細結構具有雙孔徑的現象，其大孔可以減少流阻和使蒸氣排放順利，進而使最大熱傳量與總熱阻值皆優於鎳毛細結構。

關鍵字

複合式平板型迴路式熱管 ； 毛細結構 ； 泵 ； 流量 ； 鐵氟龍

並列摘要

Loop heat pipes have the advantages of phase changing, high heat flux capability, longer distance heat transport and small thermal resistance. The aim of this study is to develop the flat plate loop heat pipe (FP-LHP) cooling system for high heat flux equipment, such as nuclear power plants, supercomputers, and high speed networks. The hybrid FP-LHP combined active mechanical pumping force with passive capillary structure. The operating characteristics of the hybrid FP-LHP was investigated in the range of flow rates from 0.3 L/min to 1.5 L/min. To evaluate the effect of the heat leakage, nickel and PTFE are used as materials of capillary structure for the hybrid FP-LHP.
In testing the nickel-water hybrid FP-LHPs at flow rate 0.6L/min, the maximum heat load achieved is 1200W (heat flux 153.1 W/cm2) and the minimum thermal resistance is at a level of 0.09 ℃/W. The effect of the flow rate shows that there is a minimum value of the total thermal resistance at the optimal flow rate. For a nickel and a PTFE wick, the corresponding flow rate are 0.9 L/min and 1.2 L/min, respectively. To reduce the level of the hybrid FL-LHP operating temperature, acetone is used as working fluid. At the optimal flow rate and a maximum allowable of the evaporator’s wall temperature about 100℃, with the use of a nickel wick the maximum heat load is 700W (heat flux 89.3 W/cm2) and the minimum of the total thermal resistance is 0.07 ℃/W; for the PTFE wick the maximum heat load achieved is 900W (heat flux 114.8 W/cm2) and the minimum of the total thermal resistance is 0.04 ℃/W。A PTFE wick has the maximum heat load transfer 30% greater than a nickel wick. With the same testing conditions and for electronic cooling the evaporator’s wall temperature does not exceed 85℃. In this case, a nickel wick’s heat load is about 500W (heat flux 63.8 W/cm2) and for a PTFE wick this value is up to 800W (heat flux 102.9 W/cm2), which is 60% larger than a nickel wick. The minimum of the total thermal resistance for a nickel wick is 0.07 ℃/W and for a PTFE wick it is 0.04 ℃/W, which is lower than a nickel wick about 43%。Moreover, the results of testing indicate that the heat leakage has the limited influence for the hybrid FP-LHP system. From the Mercury Porosimeter, the PTFE wick has biporous distribution. With the big pore radius, it can not only decrease the hydraulic drag but also release the vapor smoothly. For the hybrid FP-LHP system, the most efficient wick structure is PTFE.

並列關鍵字

Hybrid Flat Plate Loop Heat Pipe ； Wick Structure ； Liquid Pump ； Flow Rate ； PTFE

參考文獻

[2] James Thomson, “On certain curious motions observable on the surfaces of wine and other alcoholic liquours,” Philosophical Magazine Series 4, vol. 10, issue 67, pp. 330-333, 1984.

[6] Abe, Y., “Self-Rewetting Fluids Beneficial Aqueous Solutions,” Space Technology Group, AIST, Tsukuba, Ibaraki 305-8568, Japan, 2006.

[7] C. C.Yeh, C. N.Chen and Y. M.Chen, “Heat transfer analysis of a loop heat pipe with biporouswicks,”International Journal of Heat Mass Transfer, Vol. 52, pp. 4426–4434, 2009.

[9] Maidanik, Y.F., Vershinin, S.V., and Chernysheva, M.A., “Development and Tests of Miniature Loop Heat Pipe with a Flat Evaporator,” SAE Paper No.2000-01-2491, pp.652-656, 2000.

[11] Maidanik, Y.F., Pastukhov, V.G., Vershinin, C.V., and Korukov, M.A., “Miniature Loop Heat Pipe for Electronic Cooling,” Applied Thermal Engineering 23, pp.1125-1135, 2003.