雙孔徑分佈毛細結構迴路式熱管之性能提升研究

Heat Transfer Enhancement of a Loop Heat Pipe with Bidispersed Wicks

阮俊嘉(Chun-Chia Juan)

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(2010年)

https://doi.org/10.6342/NTU.2010.03476

摘要

本研究旨在發展高性能雙孔徑毛細結構(Bidispersed wick)，將之運用於迴路式熱管，改善傳統單徑毛細結構在高熱通量下的性能衰減現象，並探討孔洞球粒徑參數對系統熱傳性能的影響。研究方法為利用混煉製作孔洞球，燒結成具雙孔徑分佈之毛細結構。利用二水準因子設計的統計方法，分析不同的孔洞球平均粒徑(53、82μm)與分佈範圍寬廣(14、42μm)，對迴路式熱管的熱傳能力之影響程度與趨勢，建立統計經驗模型，以找出最佳的雙孔徑毛細結構參數，並與單孔徑毛細結構做熱傳性能的比較。
研究結果顯示，孔洞球平均粒徑大小對迴路式熱管熱傳能力的影響程度最大，其貢獻度由統計結果發現約占92.8%，而孔洞球粒徑分佈範圍在本實驗參數範圍內為不顯著因子，貢獻度僅2.9%；且在孔洞球平均粒徑較小、分佈範圍較廣的情況下，可獲得性能較佳的雙孔徑毛細結構。透過追蹤性實驗結果，最佳的雙孔徑毛細結構之孔洞球粒徑範圍為20μm~62μm。
實際測試結果在熱沉10℃與容許溫度85℃下，結果顯示最佳之雙孔徑毛細結構其總熱傳量可達575W、最低熱阻為0.13℃/W，比起單孔徑毛細結構的熱傳性能400W、熱阻為0.16℃/W，有效提升迴路式熱管熱傳能力。此外，在毛細結構熱傳能力方面，在400W時，其蒸發器熱傳係數最高可達到23.3 kW/m2.℃，約為相同瓦數下單孔徑毛細結構10.3 kW/m2.℃的2.3倍，因此，雙孔徑毛細結構在高熱通量下的應用相當具有競爭力。

關鍵字

迴路式熱管 ； 雙孔徑毛細結構 ； 熱傳係數 ； 高熱通量

並列摘要

The purpose of this article is to develop high-performance bidispersed wicks utilized in a LHP’s evaporator and to improve heat transfer crisis in formerly monoporous wicks. The influence of heat transfer performance about difference pore-size parameters will be discussed. The study was conducted by sintering the nickel powder clusters, which mixed with binder into a bidispersed wick. A two-level factorial plan of statistical design was introduced involving two variables: the average cluster size (53、82μm), and the cluster size distribution range (14、42μm). Moreover, the statistical model was built to determine the optimized parameter combination of the bidispersed wick. Finally, the heat transport capability of the LHP between monoporous wicks and bidispersed wicks has been investigated.
The experimental results indicated that average cluster size is the major effect (92.8%) on LHP’s performance about pore-size parameters, and the effect of cluster size distribution range was not significant (2.9%) within the parametric range. The better pore-size parameter tended to smaller average cluster size and wider cluster size distribution range. The best pore size parameter of the bidispersed wick was 20μm~62μm, which obtained by follow-up experiments.
Experimental results also showed that at the sink temperature of 10℃ and the allowable evaporator wall temperature of 85℃ the maximum heat transfer capacity of monoporous wick achieved 400W and the minimum total thermal resistance was 0.16℃/W. Comparing to the monoporous wick, the corresponding values of the best bidispersed wick was 575W for heat transfer capacity and 0.13℃/W for total thermal resistance. In addition to the heat transfer ability of porous wicks, the best Bidispersed wick showed higher heat transfer coefficient of 23.3 kW/m2℃ at 400W than monoporous wick of 10.3 kW/m2℃ by 2.3 times. In conclusion, bidispersed wicks are very attractive for high heat flux applications.

並列關鍵字

Loop heat pipe ； Bidispersed wick ； Heat transfer coefficient ； High heat flux

參考文獻

[20] 王鴻儒, “材料及製程參數對射出成形元件品質影響之研究”, 台灣大學材料科學與工程研究所碩士論文, 2004.

[2] Liao, Q., and Zhao, T. S., “Evaporative Heat Transfer in a Capillary Structure Heated by a Grooved Block,” Journal of Thermophysics and Heat Transfer, Vol. 13, pp. 126-133, 1999.

[5] Rosenfeld, J. H. and North, M. T., “Porous Media Heat Exchangers for Cooling of High-power Optical Components,” Optical Engineering, Vo1.34, No.2, pp.335-341, 1995.

[8] Wang, J. and Catton I., “Evaporation Heat Transfer in Thin Biporous Media”, Journal of Heat and Mass Transfer, Vol.37, No.2, pp.275-281, 2001.

[9] Cao, X. L., Cheng, P., and Zhao, T.S., “Experimental Study of Evaporative Heat Transfer in Sintered Copper Bidispersed Wick Structures,＂ Journal of Thermophys and Heat Transfer, Vol. 16, No.4, pp.547–552, 2002.