Heat transfer performance comparison of silicon-based micro oscillating heat pipes with and without expanding channels

doi:10.11949/j.issn.0438-1157.20161461

Abstract

Abstract:

A simultaneous flow visualization and temperature measurement experiment has been carried out to investigate the heat transfer characteristics and flow behavior of two silicon-based micro oscillating heat pipes (Micro-OHPs) with straight and expanding channels. R141b was used as the working fluid with the volumetric filling ratios ranging from 40% to 60%. Experimental results show that the micro-OHP with expanding channels (#2 micro-OHP) has a better thermal performance, a lower start-up evaporator temperature (or start-up power input) than that of the micro-OHP with straight channels (#1 micro-OHP) at the vertical orientation. Compared to #1 micro-OHP, at the filling ratio of 60%, the reductions in the start-up power input and start-up evaporator temperature of #2 micro-OHP were about 0.4 W and 17.3℃, respectively. Intensified nucleate boiling and bubbly flow were observed in #2 micro-OHP as compared to #1 micro-OHP, and the transient circulation flow was only observed in the latter.

Key words: micro oscillating heat pipe, expanding channel, heat transfer characteristic, flow pattern, nucleate boiling

摘要：

为了解截面结构对微型脉动热管传热性能和内部工质流动特征的影响，采用可视化和温度测量的方法对比研究了等截面和变截面硅基微型脉动热管内的工质运动和传热特性。实验工质为R141b，充液率为40%～60%。实验结果发现，变截面通道结构的设计不仅有利于降低微型脉动热管的热阻，提高其传热能力，同时可有效改善其启动性能。随着充液率的增大，该优势更加明显，当充液率约60%时变截面微型脉动热管的启动功率和启动蒸发段平均温度比等截面热管分别下降约0.4 W和17.3℃。另外，因变截面结构而形成的附加毛细作用可使微型脉动热管内工质发生短暂定向运动，而在等截面热管中则未观察到上述现象。

关键词: 微型振荡热管, 变截面, 传热特性, 流型, 核态沸腾

CLC Number:

TK124

SUN Qin, QU Jian, YUAN Jianping. Heat transfer performance comparison of silicon-based micro oscillating heat pipes with and without expanding channels[J]. CIESC Journal, 2017, 68(5): 1803-1810.

孙芹, 屈健, 袁建平. 等截面和变截面通道硅基微型脉动热管传热特性比较[J]. 化工学报, 2017, 68(5): 1803-1810.

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