Research On Design And Optimization Of Air Cooling Structure Of Electric Vehicle Battery Pack

With the deterioration of the global environment and the increasingly severe shortage of resources,governments around the world have gradually increased their support for new energy vehicles.From the current development of new energy vehicle technology,the key performance of power battery still need to be broken through,such as energy density,cycle life and safety.Lithium-ion battery is widely used in various new energy vehicles at present because of its high energy density,no memory effect and low self-discharge rate.However,the performance of lithium-ion battery is sensitive to temperature.In the process of continuous discharge,the heat generated by the battery will accumulate in the battery pack with time.If the heat is not effectively exported in time,the battery pack will lose control of heat due to the high temperature.However,pure electric vehicles usually use power batteries of energy type,which are suitable for small rate permanent discharge process.Its heat production is small,but with the characteristics of accumulation over time,so most pure electric vehicles use air cooling system to adjust the battery temperature and reduce the additional energy consumption of the vehicle.Therefore,the air cooling structure with efficient and reasonable is great significance to the thermal performance of lithium battery pack and the improvement of vehicle range.Based on the way of air cooling and combined with CFD method,the structure of air cooling chamber is studied firstly in this paper.By adjusting the angle between the distribution plenum and the convergence plenum and the length of the inlet and outlet passage to improve the heat dissipation performance of the box for battery pack.In the study of the influence of plenum angle,the influence of two plenum angles is studied firstly.On the basis of determining the influence of the angle change of the distribution plenum on the heat dissipation performance and according to the number of batteries,the distribution plenum is divided into eight equal parts and the local optimal structure of each part is studied.On the basic,the influence of the length of the inlet and outlet passage on the cooling effect and the optimal matching of the inlet air-speed and temperature are also studied.The results show that the structure of the box with reasonable design can improve the thermal performance of the battery pack greatly.And then,adding spoilers in the box also can optimize the heat dissipation performance of the battery pack in this paper.That is,adding spoilers in the bottom plate of the distribution plenum and the cooling channel to optimize the heat dissipation performance of the battery pack.The results show that the combination of the number and position of the spoilers,the angle and the height of the spoilers have a great influence on the cooling performance.And when all the factors are locally optimal,the cooling effect of the battery pack will be further improved.In addition,changing the width of cooling passage and the spoiler in cooling passage,and the air-speed of inlet can improve the heat dissipation performance of the battery pack.Based on the CFD simulation,the structure of plenum,the matching of air speed and temperature,and the optimization of the spoiler are studied and analyzed in this paper.Compared with the original Z-type cooling structure,the optimized model has a great improvement in reducing the maximum temperature and the maximum temperature difference of the battery pack,and the relevant conclusions in this study have a certain reference value for the innovative design of the air cooling and cooling system of the battery pack.