Research On The Thermal Equilibrium Of Power Battery Liquid Cooling System Of Electric Vehicle

In recent years,with the country's vigorous promotion of the new energy vehicle industry,electric vehicle,as an important direction,has aroused widely attention.As one of the core parts of electric vehicles,the performance of power battery is greatly affected by temperature.Too high or too low temperature will directly lead to the performance attenuation and reliability decline of battery and in extreme cases it will lead to permanent attenuation or even thermal runaway.In addition,when considering the temperature rise,temperature consistency of battery is also important and directly affects the use of battery system.Therefore,efficient and stable thermal management is very important for battery systems.On the basis of the summaries of main methods and research of battery thermal management,this paper studies the thermal equilibrium performance of battery liquid cooling thermal management system by using the theory of heat transfer and computational fluid dynamics,which is now hot in battery thermal management research of electric vehicle.Firstly,the heat generation model of 38 Ah prismatic cell is established.The heat generation power under different discharge rates,which is tested through charge and discharge experiments,is used as the heat boundary input for CFD simulation.Otherwise,this paper builds the finite element model of battery module and makes simulation to the module with straight-channel cold plate.Then the heat and flow distribution of battery module can be obtained.Next,according to the distribution characteristics of straight-channel cold plate,splitters are added into the straight channel to improve the thermal equilibrium of battery module.The analysis of splitters is carried out from two aspects: the layout of splitters and the structural parameters.In the optimization of structural parameters,orthogonal experimental design is used and the range of each factor is analyzed.The results show that compared with the average temperature difference of battery module without splitters,adding splitters to cool the battery module under 3C discharge rates can reduce the maximum average temperature difference by 43.5%.The deflection angle and length of splitters influence the thermal equilibrium of battery module more than other factors.Otherwise,the optimization scheme of liquid cold plate with splitters is obtained.Finally,this paper builds the model of power battery system and applied the optimized scheme of liquid cold plate with splitters to this system.The simulations of battery system under different discharge rates and different coolant flow are made to obtain the heat and flow distributions.The simulation results show that the liquid cooling system using optimized splitters can control the maximum temperature in 44.31 ? while the temperature difference of each cell in 2.853?,which can meet the temperature demands of power battery system in vehicle.