Transient properties of bifacial evaporator loop heat pipe

doi:10.11949/j.issn.0438-1157.20151669

Abstract

Abstract:

Loop heat pipe (LHP) is an efficient two-phase heat transfer device, mainly applied to spacecrafts and terrestrial electronics with high heat density. The existing flat loop heat pipes (FLHPs) are only used a surface to dissipate heat. Thus, the adverse back-conduction makes it difficult for FLHPs to startup at low heat loads, and also, the another surface of the flat evaporator possesses the potential for heat rejection. Aiming at the disadvantages above, a methanol-copper loop heat pipe with a bifacial evaporator was developed in this paper. Under the conditions of assisted-gravity angle at 10° and heat sink temperature at 0℃, startup performance and variable heat load operation were investigated with one surface heated and two surfaces heated simultaneously. The experimental results indicated that this loop could start up successfully and operate normally when one surface or two surfaces worked, but startup process with two surfaces heated showed faster and more stable. With heat source simulator wall temperature below (90±2)℃, the evaporator with one surface heated could transfer the maximum heat load of 210 W, corresponding to a heat flux of 21.8 W·cm^-2, while 240 W at the evaporator with two surfaces heated. For operation with alternative heat load, the LHP could quickly shift from one surface to another surface, and operation failure was not observed.

Key words: flat LHP, bifacial evaporator, temperature instability, two-phase heat transfer, steady state

摘要：

环路热管是一种高效的两相热控装置,主要应用于航天航空热控和地面高热流电子器件的散热。现有的平板式环路热管只有一个面可以进行散热,一方面,不利的背向导热使得环路热管在低热负荷的条件下启动困难,另外,蒸发器的另一个面也存在散热的潜能。针对上述不足,提出了平板型甲醇-铜双面蒸发器环路热管。在重力辅助倾角为10°,热沉温度为0℃的条件下,对单面加热和双面加热的启动性能和变工况运行进行了实验研究。实验结果表明:该新型环路热管在单面加热和双面加热条件下,均可以成功启动和正常运行,且双面工况时的启动性能比单面更稳定、迅速;在加热面的温度不超过(90±2)℃的情况下,单面可以传递的最大热负荷为210 W,对应热流为21.8 W·cm^-2,而双面传递的最大热负荷为240 W;双面交替运行时,LHP能够快速从一个面转向另一个面运行,没有出现运行失败。

关键词: 平板式环路热管, 双面蒸发器, 温度波动, 两相传热, 稳定状态

CLC Number:

TK124

HE Song, LIU Zhichun, WANG Dongdong, LIU Wei, YANG Jinguo, ZHANG Xiaoyu. Transient properties of bifacial evaporator loop heat pipe[J]. CIESC Journal, 2016, 67(5): 1778-1783.

何松, 刘志春, 汪冬冬, 刘伟, 杨金国, 张晓屿. 双面蒸发器环路热管的瞬态特性[J]. 化工学报, 2016, 67(5): 1778-1783.

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