Experimental analysis of a Vapour-Liquid Separated Flat Loop Heat Pipe Evaporator System

Yang Yang,Wei Jie,Sarula Chen,Wang Yabo,Zhu Kai,M El Ganaoui,S Morsli,B Liu,M Darcherif,R Bennacer

doi:10.1051/matecconf/202030701055

Yang Yang, Wei Jie + Show 8 more

Open Access

https://doi.org/10.1051/matecconf/202030701055

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Abstract

In this paper, a unique operation mechanism of loop heat pipe (LHP) was proposed. To test the performance of LHP under this new mechanism, a visual flat LHP evaporator prototype and an open experimental system were designed and assembled, and start-up experiment and variable heat load experiment were done respectively to obtain the actual operation characteristics, such as the evaporator thermal resistance (Re), total thermal resistance (Rt), start-up time and temperature of base plate. The proposed LHP had better overall performance during the start-up tests when He value of EC was set to 0.5mm, and its corresponding Re and Rt value were 0.035 K/W and 0.451 K/W when the heating power was 208w. Meanwhile, as per the heat load applied to the base plate, the whole variable heat load experiment could be divided into three distinct stages: low heat load stage, efficiency operation stage and dry-out stage. Moreover, the results also showed that the circulation driven head formed inside of the EC played an important role in promoting the operation performance, especially when the wick, the vapour-liquid interface and the bottom of the evaporator arrived at a reasonable situation.

Highlights

It is known that the cooling device is critical to promote high heat flux components’ operation reliability, performance improvement and lifespan extension [1, 2]
It was assembled by capillary wick, evaporation chamber (EC) which was under the capillary wick, pressure-balance chamber (PbC) which located at the outlet of evaporator, compensation chamber (CC) which was above the capillary wick, vapour removal outlet and the liquid supply inlet
This paper focused on a visualization evaporator of flat loop heat pipe (FLHP) with special structure in which there is no contact between base plate and capillary wick, i.e., the vapourliquid interface was separated from the capillary wick directly

Summary

Introduction

It is known that the cooling device is critical to promote high heat flux components’ operation reliability, performance improvement and lifespan extension [1, 2]. A condenser is indispensable and must be connected to the evaporator by two separate pipes to form a closed cycle This kind of design and operation mechanism of traditional LHP above usually leads to the greater flow resistance inside of the LHP, letting heat transfer efficiency limits become an inevitable problem [25, 26]. The capillary wick inside of this type LHP plays a vital function in driving working fluid at condenser back to evaporation to maintain the operation cycle, while the driving force is mainly generated at the location of phase change interface in the pore of capillary wick [27]. The inevitable problems above have extremely negative impacts on the further application

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Conclusion