| Due to the increasing environmental problems and energy crisis,new energy vehicles with outstanding advantages in reducing the consumption of petroleum resources and reducing pollutant emissions have received widespread attention in the world in recent years.As the power source of electric vehicles,the power battery packs will directly determine the performance of the electric vehicles.When the power battery is operated in a high temperature environment or a large current is charged and discharged,the battery temperature will rapidly rise,causing the battery cycle life to decline,and even causing the battery to explode and other safety issues.On the other hand,if there is a large temperature difference between the battery cells in the power battery pack,the overall performance of the battery pack will be reduced.In order to control the temperature of the power battery within a suitable temperature range and ensure the uniformity of the battery temperature,it is necessary to design a reasonable battery thermal management system for the battery pack of the electric vehicle.Based on the liquid cooling system for copper flow,this paper analyzes the influence of different factors on the heat dissipation and temperature uniformity of the system.In addition,a channel layout optimization method based on genetic algorithm is proposed.According to different optimization objectives,the corresponding optimal channel layout scheme is obtained through optimization calculation,and the influence of the layout of the channel in the system on the evaluation indicators of the battery is analyzed.Provides design basis for the design of related battery cooling systems.The main research work and conclusions are as follows:(1)The simulated liquid cooling system was simulated using Fluent.The results show that with the increase of discharge rate,the overall temperature of the batteries rise sharply,and the temperature uniformity decreases.With the increase of the ambient temperature,the overall temperature of the batteries is increased.As the temperature rises,the temperature uniformity slightly increases with the decrease of the heat generation rate of the batteries;as the cooling water flow rate increases,the overall temperature of the batteries decrease slightly,and the cooling water flow rate continues to increase when the flow rate exceeds 0.1 m/s.The battery temperature will no longer be significantly reduced.Under excessively high battery discharge rate or high temperature environment,the system's ability to dissipate heat from the battery pack will be lost.(2)The layout of the channel in the battery pack has a great influence on the heat dissipation capability of the liquid cooling system.By changing the layout of the channel,the maximum temperature of the battery can be reduced.However,if there is still a battery cell with only one contact surface with the channel,the change of the channel structure has a limited effect on the improvement of the maximum temperature of the battery.The structure of the flow channel is changed so that there is no battery cell having only one contact surface with the channel in the system,and the maximum temperature of the battery can be greatly reduced.(3)If the temperature of the cooling water in the channel changes only in a small range,the average temperature of the battery cells which have more than one contact surface with channel will be significantly lower than the average temperature of the battery cells which have only one contact surface with channel.By changing the layout of the channel in the system and increasing the number of battery cells which have more than one contact surface with channel,the average temperature of the batteries can be effectively reduced.(4)The maximum difference in average temperature is mainly determined by the minimum value of the average temperature of the battery cells.By reasonably raising the minimum value of the average temperature of the battery cells,the maximum difference in average temperature can be reduced.When all the battery cells have only one contact surface with the channel,the minimum value of the average temperature of the battery cells is the highest,and the system has the smallest average temperature difference.(5)Divide the battery cells in the system into two types that have only one contact surface with the channel and the contact surface with the channel is larger than one.When the proportion of any type of battery cells in the system increases,the consistency of the temperature distribution of each battery in the system will enhance,and the standard deviation of the battery temperature will decrease.(6)With the channel layout optimization method based on the genetic algorithm,the goal of minimizing the maximum temperature of the batteries,minimizing the average temperature of batteries,and minimizing the standard deviation of the battery temperature can be effectively optimized.However,when the goal of minimizing the maximum difference between the average battery temperature is optimized,the calculation is trapped in a local optimal solution.By optimizing the channel structure,the average temperature of batteries and the standard deviation of the battery temperature can be significantly reduced. |
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