| In order to alleviate environmental pollution problems,the government vigorously promotes the development of new energy vehicles.The performance of batteries is directly related to the endurance,safety and life of electric vehicles.The discharge capacity of the battery is closely related to the temperature,especially the temperature uniformity of the battery pack.Too high temperature or too large temperature difference can even cause the battery catch fire.Therefore,in order to keep the battery pack within the proper operating temperature range,an auxiliary thermal management system is required.In this paper,a liquid cooling structure is designed based on the harmonica tube type liquid cooling plate and its heat dissipation performance and energy consumption are studied.The specific research contents are as follows:(1)According to the size of the battery module,the parallel flow channel and the U-shaped flow channel liquid cooling structure are designed.And several evaluation indexes including the maximum temperature and the average temperature of the thermal pad,the maximum temperature difference on the upper surface of the thermal pad,flow resistance and flow distribution uniformity are proposed.(2)Based on CFD(Computational Fluid Dynamics),the steady-state simulation of the liquid cooling system is carried out,and the single factor analysis is used to study the heat dissipation capacity,energy consumption and flow distribution uniformity of the two flow channels under different parameters.The results show that the heat dissipation capability of the U-shaped channel is better than that of the parallel channel under the same conditions,but the energy consumption is also higher than that of the parallel channel.Reducing the cavity thickness,increasing the coolant flow rate,and reducing the coolant temperature are all beneficial to the heat dissipation of the battery.The correlation between the diameter of the inlet and outlet of the collector tube and the temperature is weak,but the large-diameter inlet can greatly reduce the flow resistance.The diameter of the inlet and outlet is increased from 6mm to 14mm,the flow resistance of the U-shaped flow channel is reduced by 93.1%,and the parallel flow channel is reduced by 96.6%.Finally,the flow resistance experimental test of the two liquid cooling structures is carried out to verify the accuracy of the simulation.(3)Based on the liquid-cooling structure of the U-shaped channel,further study was conducted from four aspects:the arrangement of the liquid-cooling plates,the width at the corner of the U-shaped channel,the number of channels,and the position of the inlet and outlet of the collector tube.It is found that the smaller the number of liquid cooling plates in parallel and the greater the number of channels,the better the heat dissipation of the battery.The position of the inlet and outlet has an impact on the heat dissipation of the battery pack,but it is relatively small.And the effect of the width of the corner of the Ushaped channel on the heat dissipation capacity can be ignored,but the larger the width,the smaller the flow resistance.(4)For the U-shaped liquid cooling plate,three factors are selected to design the orthogonal test,range analysis and variance analysis are used to study the influence degree of the three factors on different optimization objectives.The analysis results show that for the three optimization objectives related to temperature,the degree of influence is the number of flow channels>the arrangement of the liquid cooling plate>the thickness of the cavity.For the optimization objective of flow resistance,the degree of influence is the arrangement of the liquid-cooling plates>the thickness of the cavity>the number of flow channels.(5)Four typical vehicle driving conditions were selected as input to simulate the transient temperature field of liquid cooling system and study the heat dissipation of the battery pack under 1.6C fast charging conditions,high temperature cooling conditions,WLTC conditions and acceleration conditions It is found that the bottom temperature and average temperature of the battery pack can be reduced when there is liquid cooling,but the improvement of the top temperature is relatively weak,resulting in a large temperature difference in the z direction. |
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