Research On Coupled Heat Dissipation By Double Medium For Power Lithium-ion Battery Pack

A lot of heat will be generated when the battery pack power for the electric cars,if the heat can’t be effectively discharged,it will lead to the temperature of the battery pack rise and increase its temperature difference,which will obviously pose great threats to the safety using and cycle life of the battery.In order to control temperature rise and temperature difference in batteries,reasonable and efficient heat dissipation designs in battery packs of electric car are necessary.To solve the above problem,the use of double media coupled cooling type to the batteries cooling is studied in this paper.The main work and conclusions are as follows:(1)According to the model of cell heat build-up rate proposed by Bernardi and the thermal effect mathematical model of cylindrical lithium ion battery established by Chen Y.F,Fluent software is used to simulate the temperature field of battery cell.The simulation results are compared with the experimental result,which verifies the accuracy and feasibility of using Fluent software to simulate the temperature field of a single cell.(2)The temperature field of the cell without heat dissipation or with air cooling or with solid heat dissipation or using phase change material heat dissipation are simulated by used Fluent software.By contrast between the simulation result of whether using heat dissipation method or not,the results show that only using a cooling medium,such as gas,liquid and phase change materials to dissipate the heat of the battery pack,which can’t get satisfactory results in heat dissipation and temperature difference of the battery pack with various discharge rates.(3)Different cooling rate or liquid rate or specific heat capacity of phase change material on the heat dissipation effect and temperature difference controlling in 3C rate discharge were studied in this paper.The result shows that the greater the cooling speed and liquid speed,the better heat dissipation it effect and simultaneously the temperature difference are smaller.When using the phase change materials whose specific heat capacity is greater than 60,the higher specific heat capacity,the better heat dissipation it effect.(4)Three kinds of double medium coupling heat dissipation modes are designed,in which liquid solid coupling,gas solid coupling and gas-liquid coupling are applied to the batteries.Fluent software is used for the temperature field simulation of the battery group in liquid solid coupling,gas solid coupling,gas-liquid coupling cooling type,and compared the simulation results with the simulation results of using a cooling medium,the results show that: compared to the use of a cooling medium alone,by using double medium coupling thermal radiation on batteries its temperature and temperature difference can play a better control effect.As a whole comparison,the gas-liquid coupling heat dissipation type can cause the best comprehensive effect.