Design And Optimization Of Liquid-cooled Heat Dissipation Structure For Automotive Power Lithium-ion Battery Pack

In the context of the rapid development of pure electric vehicles,power lithium-ion battery as an important energy source of electric vehicles,its efficient,safe and stable operation is the key to ensure the performance of the car.The lithium-ion battery generates a large amount of heat during the driving process of the car,and the poor heat dissipation conditions make the heat accumulate,causing the battery temperature to be too high,reducing the performance and life of the battery,and seriously causing thermal runaway,which will seriously affect the safe driving of the car.Therefore,it is very important to design an efficient heat dissipation structure for the safe use of the battery.In this paper,the thermal safety of lithium-ion battery modules is studied in terms of thermal structure design and optimization,and the main contents and results are as follows.Firstly,the composition structure,working principle,heat generation mechanism and heat transfer characteristics of lithium-ion battery are analyzed,the thermal physical parameters and heat generation rate of the battery are obtained,and the heat generation model of the battery is established.Next,a simplified model of the battery module is established,and three cooling plates based on cobweb-like flow channels are designed.The finite element model of the module and the cooling plate is established by Star-ccm+software and CFD simulation is completed,and the six cooling solutions under two cooling medium flow directions are compared and analyzed with the traditional serpentine cooling plate.The results show that the cooling plate of CLT-I_ba cooling scheme has better heat transfer performance,lower maximum temperature of the battery module and more uniform temperature distribution.Then,based on the CLT-I_ba cooling plate,single factor analysis was used to explore and find that the cooling runner diameter,cooling plate thickness and cooling runner spacing have important effects on the heat dissipation of the battery module.Based on this,the structural parameters of the runners were optimized by orthogonal test method,and the most significant effect of the cooling runner diameter was found by extreme difference analysis and analysis of variance.The optimal combination of structural parameters was obtained by considering the maximum temperature and temperature difference of the battery module and the pressure drop of the flow channel cooling medium.The results show that the optimized cooling plate has better heat transfer characteristics,and the maximum temperature and temperature difference of the battery module are reduced by 6.8%and the pressure drop is decreased by 37.7%,which improves the heat dissipation performance of the battery module.Finally,the heat transfer performance of the cooling plate under different types of cooling medium,flow rate and initial temperature was investigated with the cobweb-like cooling plate under the optimal combination of structural parameters,and the temperature distribution of the cooling plate and the battery module under three discharge conditions was analyzed.The results show that the cobweb-like cooling plate has reliable and stable heat transfer performance,and the temperature uniformity of the cooling plate under different media factors is high,especially under the high discharge rate of the battery,the temperature rise and temperature uniformity of the battery module are at a better level.On this basis,the optimal heat transfer performance of the cooling plate under different combinations of factor parameters is obtained by the response surface method,which provides a reference for the heat dissipation of the battery module.It is found that the excellent heat transfer performance of the cobweb-like flow channel cooling plate improves the temperature distribution uniformity of the battery module,which will provide new ideas for the design and optimization of the thermal structure of the power Lithium-ion battery in thermal management.