The Experimental Study Of Loop Heat Pipe System With Flat Evaporator Using Bimetal Wall

Loop heat pipe(LHP)is a high efficient and passive heat transfer device,which utilizes the phase changing of working fluid to transfer heat and the capiliary force generated by the porous wick to drive working fluid cycle.Compared with conventional heat pipe,LHP own many advantages.For example,no moving parts,high safety and reliability,flexible transport,long transfer distance and so on.Thus,that advantages contribute to the widely use of LHP in the fields of spacecraft thermal control,electronics cooling and battery thermal management system.This thesis introduced the system composition and working principle of LHP in detail.Besides,the heat transfer process in evaporator was analyzed.The influence of heat transfer from heating surface to compensation chamber by shell and wick on the operation of LHP was elaborated.In order to reduce the heat transfer caused by shell on the system,bimetal wall evaporator with copper heating surface and stainless steel shell was proposed to used.A flat evaporator LHP system with a wick and bimetal wall was set up.The system could start up successfully under any conditions,and the maximum heat flux density was 20.68 W/cm~2when the heating surface temperature was not more than 80?.Experimental results showed that the bimetal wall evaporator had certain advantages in improving the heat transfer ability and enhancing the stability of the system.In order to solve the heat dissipation of fuel cells,a bifacial flat evaporator LHP system was designed and built and the performance of the LHP was studied experimentally.Results showed that the thermal resistance of evaporator could affect the temperature and stability of LHP system.Reducing the thermal resistance of evaporator is an effective way to improve the performance of LHP.In this thesis,the experiments on the LHP system with flat evaporator and bimetal wall were presented,and the theoretical analysis of the phenomena in the process of starting up and heat load changing were carried out.The results of this study had a certain guiding significance for the further research and practical application of flat type LHP.