双层毛细芯对环路热管传热性能的实验分析

Experimental analysis on heat transfer performance of loop heat pipes with double-layer wicks

中文关键词: 气液两相流  蒸发  相变  传热  环路热管

英文关键词: gas-liquid flow  evaporation  phase change  heat transfer  loop heat pipe

中文摘要:

      环路热管作为一种高效的相变传热装置,其性能与位于蒸发器和储液槽之间的毛细芯结构密切相关。 为了更深入研究双层毛细芯对环路热管传热性能的影响,利用不同颗粒直径铜粉制备双层毛细芯,在毛细芯 总厚度为5mm的条件下,通过调整大粒径和小粒径层的相对厚度来改变毛细芯厚度比,对平板型蒸发器环 路热管启动和变工况运行进行实验测试。实验结果表明:在同一工况下,不同厚度比的双层毛细芯启动特性 存在显著差异,启动过程中出现小粒径层蒸发效率低引起的温度过冲和环路热管中气液两相流变化导致 的 温度振荡;同时存在一个较优的双铜层毛细芯厚度比,大粒径(180~280μm)铜层厚度为3mm可提高蒸发效 率,小粒径(56~71μm)铜层厚度为2mm可提供足够毛细抽吸力保证环路热管稳定运行。搭载该厚度毛细 芯的环路热管不仅启 动 速 度 快 (125s),而 且 总 热 阻 和 蒸 发 器 壁 面 温 度 均 最 低,最 大 加 热 功 率 达 到 120 W (21.10W/cm2),对应热阻为0.17K/W。

英文摘要:

      Loop HeatPipe(LHP)isanefficientheattransferdevice withphase-change.Itsheat transferperformanceiscloselyrelatedtothewickbetweentheevaporatorandcompensationchamber. Double-layerwickswithdifferentcopperparticlediameterswereproposedtoinvestigatetheeffectof double-layerwickonoperationalcharacteristicsofLHP.Withthetotalthicknessofallwicksof5 mm,the double-layer wick thickness ratio was varied by adjusting thelarge-diameter and small-diameterwithdifferentlayers''thicknesses.Experimentswerecarriedouttoinvestigatethewick ontheperformanceofstart-upandvariableheatloadoperation.Theexperimentalresultsindicated thattherewasasignificantdifferenceinthestart-upofthedouble-layerwickswithdifferentthickness ratiosunderthesameoperatingcondition.Temperatureovershootcaused bylow evaporation efficiencyofsmall-particlesizelayerortemperatureoscillationduetogas-liquidtwo-phaseflowchange inloopheatpipewasobservedinthestart-upprocess.Meanwhile,therewasanoptimalthickness ratiointhetwo-layercopperwickwithdifferentparticlesizes.Thatwas,the3mmthicknessofcopper layerwithlargeparticlesize (180-280μm)enhancedtheevaporationefficiency,andthe2 mm thicknesscopperlayerthicknessofsmallparticlesize(56-71μm)provideedenoughcapillaryforceto ensurethestableoperation.TheLHPequippedwiththewickoftheoptimalthicknessratiohadnot onlyafaststart-up (125s)butalsothelowesttotalthermalresistanceandevaporator wall temperatureduringtheoperation,andthemaximumheatloadwasupto120 W (21.10 W/cm), correspondingthermalresistanceof0.17K/W.