低温环路热管综述

环路热管是以多孔毛细芯抽吸力为动力的相变传热设备,可根据实际应用改变结构形式,能在远距离传热的同时保持良好的均温性,并且可在微重力环境下运行。环路热管工作温区较广,按照其工作温区一般可分为高温环路热管(350 K以上)、常温环路热管(200～350 K)和低温环路热管(200 K以下)。为了满足深空探测的需要,低温环路热管广泛应用于航天设备温控系统中并表现出优异的性能。按照孔隙特征和结构形式将用于环路热管的毛细芯分为四种,简要阐述每种毛细芯制备和特点;综合分析了近年来低温环路热管技术主要理论和实验研究成果,将目前低温环路热管常见的工作温区分成五个部分,分析影响低温环路热管传热性能的因素,包括工质充装量、反重力高度、次蒸发器功率等。最后,提出优化措施以满足未来深空以及地面应用的需求。

Review of Cryogenic Loop Heat Pipe Technology

Loop heat pipe (LHP) is an efficient two phase heat transfer device which utilizes the capillary effect of the porous wick to circulate the working fluid.Many system structures of LHP are developed to fit different applications.Loop heat pipes are capable of transferring heat over long distance while keeping the thermal homogeneity,and operating in micro gravity environment.Due to their different operating temperature range,loop heat pipes are categorized into three types: high temperature LHP(above 350 K),normal temperature LHP(200-350 K),and cryogenic LHP (below 200 K).To meet the challenging requirements of deep space exploration missions,cryogenic LHPs are utilized to collect waste heat from spaceflight and show excellent performance.Porous wicks for loop heat pipes are divided into four kinds according to porosity characteristics,and their manufacture process and features are briefly introduced.This paper reviews both theoretical work and experimental work of cryogenic loop heat pipe in recent years.Five different temperature ranges of cryogenic loop heat pipes (CLHPs) are categorized.Attention is paid to the start up and operating characteristic of different CLHP.The parameters that affect the CLHP performance are analyzed,including adverse elevation,heat load applied to the secondary evaporator,and working fluid inventory.At last,some optimization strategies are given to meet the need of future space and terrestrial applications.