Experimental And Numerical Research On Heat Transfer Characteristics Of Phase- Change Immersion Cooling Method

With the advantages of cleanliness without any pollution,high efficiency and low economical cost,concentration photovoltaic technology has attracted attention from experts all over the world.However,the problem of high temperature and non-uniform energy flux distribution on the photovoltaic cell surface exists during the solar-electric conversion process,which proposes a big challenge for the safe operation of high concentration photovoltaic system.In this paper,a series of experiments are carried out to study the performances and issues of phase-change immersion cooling method which is proposed by our laboratory in the earlier stage.Further,the CFD simulation of phase-change immersion cooling process is performed to predict the effect of various parameters on thermal characteristics.The main contents of this paper are summarized as following:1.The comparison testes between ethanol phase-change immersion cooling system and mini-channel active water cooling system have been designed and constructed in this paper,and the heat transfer characteristics are compared from thermal resistance,heat transfer coefficient and exergy efficiency in detailed.The ethanol phase-change immersion cooling method shows a more excellent thermal performance than the mini-channel active water cooling method during heat dissipation process.Therefore,it is appropriate for high concentration photovoltaic conditions.2.This paper analyses the influence of experimental parameters such as filling ratio and absolute pressure on the thermal performance of ethanol phase-change immersion cooling system.The results show that the optimal filling ratio is 30%in this paper,under this filling ratio,the thermal resistance,heat transfer coefficient and exergy efficiency are 0.479°C/W,9726.21 W/(m~2·°C)and 15.53%,respectively.3.In the phase-change immersion cooling process,the bubble generation from front surface will decrease the electrical output efficiency.This paper choses silicone glue as the encapsulant material of photovoltaic cells to avoid this phenomenon.The impact of different silicone thicknesses on the thermal performances of phase-change immersion cooling under high energy flux is considered.It can be concluded that the optimal silicone thickness is 0.611 mm.The experimental results indicate that the silicone is a suitable encapsulant material for the solar photovoltaic application.4.In this study,a two-dimension calculated model for the phase-change immersion cooling receiver under high heat flux has been derived with the ANSYS-Fluent software and further numerical predictions are then performed.The simulation results are well consistent with the experimental results.Moreover,this paper simulates the influences of different concentration ratios,inlet mass flow rates and inlet temperatures on the thermal performance and bubble motion of the system.The final results can provide theory instruction for the design and safe operation of phase-change immersion cooling system.