Heat Dissipation Structure Design And Simulation Optimization Of Electric Vehicle Power Battery Module

Today,with environmental problems and energy problems becoming more and more serious,electric vehicles are regarded as the mainstream direction of future automobile development.To this end,countries all over the world are actively seeking continuous progress in the research level of electric vehicles.Power batteries,as an energy source for electric vehicles,have become the main factors affecting the development of electric vehicles.Compared with other power batteries,lithium-ion batteries have high operating voltage,high energy density,high power density,long cycle life,and no memory effect,which makes them the first choice for electric vehicle power batteries.When working,it is often in a state of high rate discharge.The battery cells in the battery pack generate a large amount of heat.If these heats cannot be dissipated in time,their performance,safety performance and cycle life will be affected.In severe cases,it may cause thermal runaway or even fire and explosion.Therefore,in order to ensure the safety and reliability of the battery pack,it is necessary to design an effective electric vehicle power battery thermal management system to ensure that the lithium ion battery is in the optimal ambient operating temperature range for a long time.In this paper,the 18650-type cylindrical lithium-ion battery is used as the research object.Firstly,the combination of theoretical analysis and numerical simulation is used to analyze the temperature field distribution characteristics.Then,a forced air cooling system is designed.Finally,the orthogonal experimental method is used to optimize the battery box structure The main work of this paper is as follows:(1)Based on the internal structure,working principle,heat generation mechanism and heat transfer characteristics of the battery,the 18650-type cylindrical lithium-ion battery was used as the research object to establish the three-dimensional thermal effect model of the battery.The Fluent simulation software was used to simulate the temperature field and velocity field distribution of single cell discharged at 1C,2C,3C,4C rate.The simulation results show that with the increase of discharge rate,the maximum temperature and maximum temperature difference inside the single cell are getting larger and larger.It is concluded that when the battery is assembled,a proper heat dissipation system should be designed to ensure the performance of the battery.(2)Based on the battery cell simulation model,a forced air cooling system consisting of 18 lithium-ion batteries was designed and simulated by computational fluid dynamics.Then change the battery cell spacing,the air inlet air duct angle of the battery module and the offset angle of the air outlet side surface of the battery module to improve the heat dissipation performance of the battery pack,so that the maximum temperature in the battery pack is reduced from 53.3? to 36.4?,the maximum temperature difference is reduced from 13.2 ?to 3.2?(3)Using the orthogonal experimental method,the three parameters of cell spacing,inlet angle and air outlet side angle were taken as the investigation factors,and the highest temperature in the battery was used as the evaluation index to study the influence of each parameter on the heat dissipation effect of the battery.Then use the range analysis method to find significant factors and optimal parameters.The final conclusion is: the order of influence of each parameter on the maximum temperature in the battery pack is: cell spacing > air inlet angle > air outlet side angle,the optimal lithium-ion battery pack air cooling heat dissipation model is: single battery spacing is 3mm,the angle of the air inlet of the battery box is 6°,and the side angle of the air outlet of the battery box is 3°.