| With the worldwide increased environment pressure and intense energy lack,most of the major automotive-produce countries started to develop the e-cars,in order to improve the competitiveness and maintain sustainable economic and social development.The power battery is the heart of electric vehicles and the temperature and internal temperature uniformity have a great influence on the performance,safety and lifespan of the vehicle.Therefore,it’s essential to establish a reasonable and efficient battery thermal-management-system,control the battery temperature within a range and keep the consistency.In this way,battery lifespan could be prolonged thereby ensuring the safe and reliable operation of electric vehicles.In this paper,the liquid cooling system of lithium-iron phosphate battery modules is taken as the research object to study the influence of different factors of the cooling plate on the cooling performance of the battery module,optimize the design of the cooling plate and verify the effectiveness of its cooling effect,so as to improve the cooling capacity and temperature uniformity of the battery module.The main contents are as follows:(1)According to the structure and working principle of the lithium-ion battery,the heat generation mechanism and heat transfer characteristics of the lithium-ion battery are analyzed,also the battery thermal effect model is established.Based on experiments,the internal resistance characteristics of the battery are summarized,the internal resistance of the battery is measured by the AC measurement method,the heat generation rate of the battery is calculated based on the Bernardi heat generation rate model,and the thermal physical parameters of the battery are obtained by an equivalent method,which provided the data basis for solving the battery temperature field.(2)Build the geometry model for battery pack,then design five kinds of multi-snake channel cooling plates according to the temperature distribution characteristics of the battery during operation and apply them to the lithium-ion battery pack liquid cooling system model.The grid division and grid independence verification of the lithium-ion battery pack liquid cooling system model is carried out to ensure the accuracy and speed of the simulation calculation.The engineering calculation formula method is used to calculate the Reynolds number,to judge the fluid flow state and give the boundary conditions of the fluid simulation and the relevant attribute parameters of the cooling plate.(3)Based on the theory of computational fluid dynamics,the effects of the cooling channel area,liquid flow direction,gradient direction of the channel,the position of the channel and the layout of the cooling plate on the cooling performance of the battery module are studied.The results show that as for the cooling plate with multiple serpentine flow channels with 2mm gradient after optimizing the position of the channels,the battery module works in the appropriate temperature range and the maximum temperature difference is only 2.40 K,the heat dissipation effect is better in case of the second flow channel is countercurrent and the gradient direction of each flow channel is the same.Under the same flow channel,the asymmetric distribution of the cooling plate is more conducive to reducing the maximum temperature of the battery module,reducing the temperature difference and improving the temperature consistency.(4)An experimental platform is built to conduct experimental research on the heat dissipation effect of the liquid cooling system of lithium-ion battery packs using the optimized cooling plate.The results illustrates that the experimental data are similar to the simulation results and the design of the cooling plate flow channel is reasonable and feasible,that can provide some guidance for the design of the cooling plate flow channel of the battery liquid cooling and heat management system in engineering. |
PDF Full Text Request