Research And Optimization Of New Energy Vehicle Battery Thermal Management System

As the power source of new energy vehicles,lithium-ion batteries are susceptible to temperature during operation,and a large amount of heat is generated and gathered when the batteries are continuously discharged.If the heat does not dissipate in time,it will affect the performance of the battery,which in turn will affect the power and safety of the car.Therefore,the thermal management system configured in new energy vehicles can effectively control the temperature of the battery pack,improve the battery life and ensure the normal operation of the battery system.In this paper,the heat generation of a single cell under different conditions is simulated and analyzed by ANSYS software,and the accuracy of the thermal effect model and heat generation calculation model established in this paper is verified by comparing the simulation and experimental results.The cooling effect of different arrangements and heat dissipation structures on the battery pack under low discharge rate is investigated by using air-cooled heat dissipation method,and structural optimization and orthogonal test analysis are carried out to arrive at the best heat dissipation structure and scheme.Finally,AMESim software was used to simulate and analyze the effects of different cooling conditions on air-cooled and liquid-cooled heat dissipation,and to determine the appropriate thermal management system under different conditions by comparing the temperature uniformity.The main research results are as follows:(1)The simulation calculation results of single cell battery show that: when the ambient temperature increases,the difference between the maximum temperature and ambient temperature of the battery gradually decreases;when the discharge multiplier increases,the heat generation of the battery increases,and the maximum temperature and maximum temperature difference also increase;when the convection heat transfer coefficient increases,the temperature rise of the battery is smaller,but the temperature difference between inside and outside increases.(2)The results of battery pack temperature field distribution under various schemes such as different arrangements and heat dissipation structures show that: compared with arrangement one,the remaining two arrangements effectively reduce the maximum temperature and maximum temperature difference of the battery pack,and arrangement two has the best cooling performance;compared with the original structure scheme,the other three structure schemes have better heat dissipation,and structure scheme three increases the ventilation holes,and the maximum temperature and maximum temperature difference of the battery pack decreases the most and has the lowest value,and has the best heat dissipation effect.(3)The numerical simulation results of the optimized heat dissipation structure show that the optimized structure effectively reduces the temperature rise and the maximum temperature difference of the battery pack,after optimizing the number of ventilation holes,optimization scheme 2 has the minimum temperature rise,the maximum temperature difference of the three arrangements after the optimization of the added fin structure was controlled within 5℃,and the temperature uniformity is better.Through two orthogonal tests,the influence of several factors on the maximum temperature and maximum temperature difference is studied.The best combination of the first orthogonal test is arrangement 2,the inlet wind speed is 4 m/s and the number of vents is in 3 rows.In the second orthogonal test,the angle difference of adjacent fins is 10 and the vertical height difference of adjacent fins is0.5mm.(4)The analysis results of the one-dimensional model of air and liquid cooling system show that increasing the inlet air speed and inlet mass flow rate can effectively improve the effectiveness of air-cooled and liquid-cooled heat dissipation of the battery pack,and the maximum temperature difference of the battery pack of the liquid cooling system is only1.59℃ under high multiplier discharge,which is better than that of the air cooling system,and the temperature uniformity is better.