Heat Dissipation Analysis And Optimization Of The Pure Electric Bus Lithium-ion Battery Pack Based On CFD

Aiming at the problem of poor heat dissipation in the battery box of a pure electric bus,the battery box cooling system of the car is considered in this paper,the model to calculate the heat generation rate of lithium-ion battery is established,the geometric model of power battery box is established by UG,and the function of surface reconstruction,Polyhedral grid generator and solving are used via STAR-CCM+,then the velocity field and temperature field are simulated and analyzed.By adding the flow guiding plate,the battery box is improved for better heat dissipation and the orthogonal experiments are carried out.The main results in this paper are as follows:(1)The heat generation mechanism of lithium-ion battery and the formula of battery heat generation rate are investigated in this paper,and the model to calculate the heat generation rate of lithium-ion battery is simplified;(2)Through the comparison for the heat dissipation mode of the battery pack,the cooling mode of the battery box as forced air cooling is selected,then the three-dimensional geometric model of the battery box is designed,and the three-dimensional geometric model is simplified,and the simplified three-dimensional geometry is meshed with a hexahedron by the STAR-CCM+ software;(3)When the power battery is working under the limit conditions of a pure electric passenger car,the CFD simulations and analysis are performed by STAR-CCM+ software on the original battery box,and the improvement measures are proposed for the insufficiency of the original battery box,the method of orthogonal test is adopted to reduce the number of tests.Two excellent programs are obtained through the analysis of the multi-index experimental data and the comprehensive balance method of the orthogonal test,and then the CFD simulations are performed on the two programs,the optimal program is obtained after the data comparison.Finally,the flow rate and temperature of the air in the battery box entrance are adjusted,and the air movement direction in the battery box is changed,the simulation results of the optimal program and the original battery box are compared with each other,it shows that the maximum temperature of single cell is reduced by 3.06%,the temperature difference between the single cells is reduced by 74.44%.