Research On The Performance Of The Integral Cooling Plate For The Power Battery Of Battery Electric Vehicle

In recent years,China’s car ownership continues to rise,China’s"fourteenth five year"development plan has opened a new era of China’s automobile industry,the gradual improvement of people’s awareness of environmental protection,the increasing amount of fuel vehicle pollution,the shortage of non renewable resources and other issues promote the development of automobile industry towards the direction of low-carbon vehicles.New energy vehicles have outstanding advantages in reducing resource consumption and pollutant emissions,and are increasingly becoming the key direction of the development of the automotive industry,while pure electric vehicles account for most of the sales of new energy vehicles.Power battery pack is the power source of pure electric vehicle.The temperature of power battery pack plays a decisive role in the life and safety of the vehicle.At present,the battery thermal management technology of pure electric vehicle has been paid more and more attention.In order to effectively heat the battery pack,this paper uses the methods of experimental verification,three-dimensional numerical simulation and structural coupling optimization to design and compare the performance of the cooling plate of the single-mode battery pack,and integrates the cooling plate of the single-mode battery pack to design an integral liquid cooling plate.The performance of the cooling plate is analyzed from different angles,and the flow uniformity and temperature of the integral cooling plate are discussed Finally,some suggestions are given to optimize the structure of the cooling plate.Firstly,taking 50ah lithium iron phosphate battery as the test object,the change law of internal resistance and temperature rise of the battery were studied.According to the test data,the thermal simulation model of the battery unit was established,and the simulation data and test error were controlled within 5%,which met the requirements.Secondly,this paper designed eight different cooling structures of the single-mode battery group,such as the convex type liquid cooling plate and the serpentine tube type liquid cooling plate.The three-dimensional numerical simulation method was used to compare and analyze the flow resistance,flow distribution,heat dissipation performance and economy.The results show that the comprehensive performance of the double inlet parallel serpentine tube liquid cooling plate is the best.The effects of different channel width b₁,outlet channel width b₂,channel height h,channel slopeαand cooling plate thickness d on the flow resistance and heat transfer performance of liquid cooling plate were investigated.In addition,based on the L16（4⁵）orthogonal test,the maximum surface temperature of the cooling plate and the flow resistance of the inlet and outlet are taken as the evaluation indexes to optimize the design of the double inlet parallel snake tube liquid cooling plate.Through range analysis method,the influence of cooling plate parameters on heat transfer performance and flow resistance performance is obtained,and the significant degree is channel width b₁>channel height h>channel inlet width b₂>channel slopeα>cooling plate top plate thickness d.The results show that the optimal structure of double inlet parallel coil liquid cooling plate is b₁=5.5mm,h=6mm,b₂=12mm,α=2.21%,d=3mm.After optimization,the flow resistance of liquid cooling plate decreases by 5.51%,and the maximum surface temperature of battery decreases by 1.3℃.In order to optimize the design of the temperature uniformity of the whole battery pack and reduce the flow resistance of the liquid cooling plate,this paper abandons the external pipeline of the traditional cooling plate connection,and innovatively proposes a single-mode group integrated integral cooling plate.The initial structure of the integral cooling plate is simulated by three-dimensional numerical simulation.The optimization direction of the integral cooling plate is proposed through the non-uniformity of the flow rate of the cooling plate performance evaluation index The width of the first branch header w₁ and the second,third and fourth branch header w₁ are calculated by multi-objective optimization algorithm w₂ the width w₃ of the header at the fifth and sixth branch and the width d of the inlet of the flow passage are optimized.The results show that the flow non-uniform fraction of each single cooling plate position of the optimized integral cooling plate is less than 5%,and the flow resistance is reduced by22.1%compared with that before optimization.Secondly,the temperature distribution of the optimized battery pack is significantly improved compared with that before,and the temperature uniformity is improved.The temperature difference of the optimized battery pack is less than 3℃,which meets the design requirements of the temperature uniformity of the battery pack.