| Electric vehicles with high energy efficiency and zero emissions are gradually becoming the main means of transportation.The widely used lithium-ion battery is considered to be one of the core components of electric vehicles because of its high working voltage and high energy density.Excessive temperature or temperature difference in the battery pack will reduce the performance and life of the battery,so it is very necessary to design a reasonable thermal management system.In this thesis,aiming at the traditional thermal management system of air-cooled battery,the fin structure staggered attached to the battery is designed.According to the geometric characteristics of 18650 battery,a ring fin structure staggered attached to the battery was designed.This structure can not only effectively improve the heat dissipation performance of the battery,but also adjust the fin length in a wide range,thus improving the temperature uniformity of the whole battery pack.With the help of COMSOL multi-physical field simulation software,the heat dissipation characteristics of single cell with fin structure were numerically simulated.The effects of fin length,fin number and fin thickness on the heat dissipation performance of the battery under air cooling were analyzed.The research results show that the fin structure can effectively adjust the heat dissipation rate of single cell,and it is an effective technical means to improve the air cooling effect of power battery.The staggered fin structure is applied to the battery pack,and the influence of the structure on the heat dissipation performance of the battery pack is analyzed by means of numerical simulation.Based on the model of air-cooled battery pack without fin structure,the improvement effect of three kinds of fin structure on the heat dissipation performance of battery pack is analyzed.On this basis,the temperature uniformity of the battery pack is optimized by adjusting the length of the fin.Compared with the finless battery pack,the maximum temperature of the optimized fin battery pack decreased by 3.64 ℃ and the maximum temperature difference between the batteries decreased to 86.59% at 5C discharge rate.The results show that the fin structure staggered attached to the battery can not only effectively improve the heat dissipation performance of the battery pack,but also significantly improve the temperature uniformity of the whole battery pack,which becomes an effective technical means to improve the air cooling and heat management performance of the power battery pack.By means of numerical simulation,the ability of fin structure to prevent and control the thermal runaway of battery pack is analyzed.The results show that the fin structure can effectively reduce the radiative heat transfer between the thermal runaway battery and the surrounding battery,and the maximum temperature of the peripheral battery is controlled below 28 ℃.Effectively reduce the risk of thermal runaway caused by high temperature,and then hinder the space propagation of thermal runaway. |
