Optimization Design Of Forced Air Cooling System For Lithium-Ion Battery Pack

Nowadays,energy is in short and the environment problems are severe.Lithium-ion battery is widely used in electric vehicles,wind energy storage and other fields due to their high energy density,high charge and discharge efficiency,and long life cycle.The temperature of lithium-ion battery and the uniformity of temperature distribution during the working process have great influence on its performance and life,which is directly related to the reliability in the application process.Therefore,thermal management of lithium-ion battery pack is of great significance for the safe application of batteries.The air-cooled BTMS has the advantages of simple structure and low cost,but has the problems of low heat dissipation efficiency and different heat dissipation effects.This paper uses the electrochemical-thermal model of lithium-ion battery to analyze its thermal behavior,and combines the flow resistance network model and finite element analysis method to study the structural optimization design of air-cooled BTMS The specific work is as follows:Firstly,aiming at the problem that the thermal simulation accuracy of lithium-ion battery is not high,the thermal behavior of lithium-ion battery during charging and discharging process is studied,and the electrochemical-thermal simulation model of lithium-ion battery is established.A low rate discharge experiment is carried out to realize the identification of the electrochemical parameters of the model,and the heat transfer equation is simplified to realize the decoupling and identification of the thermal parameters.The finite element analysis of the thermal behavior of lithium-ion battery is carried out by using the identified model parameters,and the electrochemical-thermal simulation model and identified parameters is validated.Secondly,aiming at the low efficiency of the air flow rate calculation of air-cooled BTMS,according to the principle of fluid mechanics,the flow resistance network model is established to realize the rapid calculation of the cooling air flow rate in each flow channel.The finite element method is used to establish the air fluid model of the lithiumion battery pack under forced air cooling to validate the effectiveness of the flow resistance network model.The air-cooled experimental platform for battery pack is built,and the model accuracy is validated under different cooling velocities and system structures.Finally,aiming at the problem of structural optimization design of air-cooled BTMS,based on the flow resistance network model,the angle of the inlet divergence plenum and the outlet convergence plenum of air-cooled BTMS is optimized using the exhaustive method,and the cell spacing distribution is optimized using the genetic algorithm.The finite element method is used to calculate the temperature distribution of the battery pack,and the optimization effect of the flow resistance network model is validated.The charge and discharge experiments are carried out on the air-cooled experimental platform of the battery pack to validate the accuracy of the temperature field simulation results using the BTMS thermal simulation model and the effectiveness of the system structure optimization design.From the perspective of improving the cooling efficiency of air-cooled BTMS,this paper establishes the battery thermal simulation model and the flow resistance network model.The design of the thermal management system structure is optimized,which achieves the purpose of reducing the overall temperature of the battery system and improving the uniformity of temperature distribution.