平板型閉迴路脈衝式熱管水平操作之研究

Horizontal Operation of Flat-Plate Closed-Loop Pulsating Heat Pipes

陳奕融(Yi-Rong Chen)

指導教授 ： 林育才

元智大學/工程學院/機械工程學系/碩士(2009年)

摘要

因脈衝式熱管無需毛細結構，吸引了許多學者在此被動式兩相流散熱增益機制之研究。近年來，平板型脈衝式熱管之特性應用在均溫板上，是一項相當具有競爭力之被動式散熱元件。本文研究試圖縮小平板型脈衝式熱管的體積，並且水平操作內部也能順利產生兩相流振盪現象，因此設計出兩種流道平板型脈衝式熱管，皆利用銅平板加工閉迴路流道，平板尺寸為122×57×5.5 mm3。均勻流道平板型脈衝式熱管的矩形流道之截面積由2×2 mm2所構成，一共有16條流道，8個彎管數；非均勻平板型脈衝式熱管的矩形流道之截面積由1×2 mm2、2×2 mm2相鄰排列所構成，一共有16條流道，8個彎管數。兩者皆覆蓋上透明壓克力板，以建立可視化模組，工作流體為純水。利用高速攝影機，觀測在水平操作下，不同熱負載時，兩相流運動型態對蒸發端溫度之影響，及其有效熱傳之方式，實際觀察到兩相流開始穩定循環流動時，將有最佳熱傳性能。實際量測熱傳性能，非均勻流道平板型脈衝式熱管在最佳填充率60%時，可得系統總熱阻為0.81(°C/W)。此非均勻流道設計在填充率低於50%時，內部無法持續產生兩相流振盪以達有效熱傳，因此熱傳接近金屬之熱傳導。而均勻流道平板型脈衝式熱管在水平操作下，不論填充率是40%、50%、60%、70%皆無法做動。

關鍵字

平板型閉迴路脈衝式熱管 ； 振盪式熱管

並列摘要

In recent years, Pulsating Heat Pipes (PHPs) without wick structures have drawn much attention of many researchers for enhancing heat transfer through passive two-phase flow heat transfer mechanism. The characteristics of flat-plate closed-loop pulsating heat pipes are applied on spreaders widely and viewed as competitive passive heat transfer devices. This research aims to experimentally investigate thermal performance of flat-plate closed-loop Pulsating Heat Pipes (CLPHPs) in horizontal operating condition. Two tested CLPHPs are made of copper capillary tubes with overall size 122×57×5.5 mm3, one of them has 16 parallel square channels with cross-section 2×2 mm2, called uniform CLPHPs, and the other one, called non-uniform CLPHPs, has 8 parallel square channels with cross-section 2×2 mm2 and 8 parallel square channels with cross-section 1×2 mm2. The working fluid used on the two CLPHPs is distilled water. Both of them are covered by acrylic plates for visualization study. By using a high-speed video camera, the effects of two-phase flow patterns on the evaporator temperature and the heat transfer mechanism for various heat loads are investigated. The results show that the optimal performance of heat transfer occurs at a steady circulating flow pattern. It is also found that, non-uniform CLPHPs with a filling ratio of 60% can operate in horizontal position and the optimal performance of overall thermal resistance is 0.81(°C/W). The operation limit of the filling ratio is 50%, below which oscillating two-phase flows disappear and the heat transfer mechanism approximates to conduction. The uniform one can’t work with any filling ratios in horizontal position.

並列關鍵字

Flat-Plate Closed-Loop Pulsating Heat Pipes ； Pulsating Heat Pipes

參考文獻

[42] 陳聖文，「平板型閉迴路脈衝式熱管性能之研究」，碩士論文，國立清華大學，2008。

[4] H. Akachi, “U.S. Patent No. 4921041,” 1990.

[12] M. Hosoda, S. Nishio, R. Shirakashi, “Study of Meandering Closed-Loop Heat-Transport Device,” JSME Int. J., Vol. 42/4, pp. 737-744, 1999.

[14] M. Misale, M. Forgheri, “ Influence of Pressure Drops on the Behavior of a Single-Phase Natural Circulation Loop : Preliminary Results,” Int. Co mm. Heat and Mass Transfer, Vol. 41, No. 8-9, pp. 1075-1086, 1999.

[15] M. Groll, et al., “Visualization of Thermofluiddynamic Phenomena in Flat Plate Closed Loop Pulsating Heat Pipes,” Proc. 6th Int. Heat Pipe Symposium, Chiang Mai, 2000.