Experimental Study Of Heat Transfer Performance Of Dual-Evaporator Loop Heat Pipe

With the development of spaceflight technology,the application of loop heat pipe(LHP)is challenged in the field of heat dissipation with high heat flux and dispersed heat source.Multiple Evaporator Loop Heat Pipe(ME-LHP)technology with higher heat transfer limit developed based on LHP technology has shown a broad application prospect in the field of heat dissipation of high precision technology such as aerospace,electronics,nuclear industry and so on.In this paper,the typical structure of ME-LHP,Dual Evaporator Loop Heat Pipe(DE-LHP),is taken as the research object.The working principle and thermodynamic characteristics of DE-LHP are described.The key design techniques and heat transfer characteristics of ME-LHP are summarized.The DE-LHP with an eccentrically separated evaporator and compensation chamber was designed,and a rotating sealing device was designed inside the evaporator.Then the theoretical minimum compensation chamber volume and the theoretical optimal filling rate of DE-LHP are calculated.According to the design of DE-LHP,the experiment system of DE-LHP is made and built.The start-up experiments were carried out under different operating conditions.The effects of vapor-liquid distribution,evaporator interaction and capillary wick seal structure on the startup performance of DE-LHP system were studied.The experiments were carried out under different operating conditions.The differences in the thermal resistance and the heat transfer limit of the DE-LHP single and dual evaporators were analyzed.The phenomenon of temperature fluctuations was explained and the DE-LHP thermal leak was calculated.Finally,the variation of the temperature control of the compensation chamber in the DE-LHP system is studied.The results show that:(1)The DE-LHP system 5W/5W start-up has the best start-up performance under the condition that the vapor exists in the grooves and the core of the evaporator is filled with liquid.(2)Vapor grooves and evaporator core full of liquid condition,dual evaporator isothermic load start.Two starting modes were observed.Mode1: The vapor flows into the evaporator before starting,and starting the evaporator at first is advantageous to start the evaporator later.Mode2: The vapor does not flow into the evaporator before starting,which hinders the start of evaporator later.Compared with mode2,mode1 has a smaller evaporator startup time difference.(3)Compared to the DE-LHP single evaporator operating "variable conductance" range 5W-25 W,DE-LHP dual evaporator operating "variable conductance" range 3W/3W-35W/35 W larger In the heat transfer limit range,the operating temperature of the dual evaporator is smaller than that of the single evaporator with the increase of heat load.The heat transfer limit of DE-LHP dual evaporator is 80 W larger than that of single evaporator running 35 W.