Analysis And Design Of Thermal Flow Field Of Power Battery Cooling System

The thermal safety of power batteries is one of the key problems faced by electric vehicles.In order to ensure the thermal safety of batteries,a cooling system for power batteries is designed in this paper.At the same time,the influence of the flow field distribution of the cooling system on the battery temperature characteristics is studied.It was found that the more uniform the flow field distribution of the heat dissipation system,the better the cooling effect for the battery.Based on the analysis of the heat generation mechanism and heat transfer mechanism of the single battery,this paper takes the ternary square battery as the research object,and establishes the mathematical model of the thermal conductivity of the battery cell.And thermal physical parameters.And through numerical methods and experimental methods,the temperature difference of the battery is less than 6%,from which the reliability of the numerical method is judged.On the basis of establishing a simplified model of the battery pack,a variety of heat dissipation structures with different flow channels are designed.One of them uses Lagrangian number multiplication to optimize fluid energy consumption under the constraint of constant structure volume,thus designing a heat dissipation structure with tree fractal as the fluid distribution method.Using STAR-CCM + software to simulate each model,the results show that the more uniform the flow distribution of the heat dissipation structure,the better the temperature consistency of the battery module and the lowest surface temperature of the module.At the same time,the influence of the three factors of battery discharge rate,ambient temperature and coolant flow rate on the battery temperature field is analyzed.Among them,the battery discharge rate factor has a larger weight.When the coolant velocities are 0.435 m / s,0.541 m / s,and 0.645 m / s,the maximum temperature difference on the battery surface is within 0.2 ° C,which has little effect.Establish the overall geometric model of the battery pack,design a heat dissipation system for it,and analyze the flow field of the heat dissipation system to obtain the flow distribution,thereby combining the fluid flow mechanism and simulation results to optimize the heat dissipation system and obtain an asymmetric tree The fractal grid is a heat dissipation system with fluid distribution.The battery pack temperature characteristics of the two heat dissipation systems before and after optimization were analyzed at their battery discharge rates of 1C,1.5C,and 2C.As the rate increased,the surface temperature of the battery gradually increased,and as the battery temperature increased.The temperature difference between the two systems after cooling is getting larger and larger.The cooling effect of the optimized heat dissipation system is significantly better than that of the pre-optimization system,and the optimized heat dissipation performance is getting better and better as the temperature increases.By using numerical simulation methods to study the heat dissipation of the battery,it is concluded that as the uniformity of the flow field distribution of the heat dissipation model increases,the better the heat dissipation performance for the battery,the battery temperature will decrease and the battery temperature will be uniform The performance is also improved,solving the battery safety and life problems.Based on the above conclusions,the flow field distribution of the heat dissipation system can be optimized through the combination of theory and simulation.The optimized asymmetric tree-shaped heat dissipation system has a more uniform flow field distribution,and the heat dissipation effect for the battery is accordingly more significant.