Research On The Heat Dissipation Characteristics Of Lithium-ion Power Battery System For Vehicles Based On Mini-channel Liquid Cooling

Vigorously developing new energy vehicles can not only save energy and reduce emissions,but also promote the secondary development of my country’s automobile industry.The Chinese government has strongly supported the new energy vehicle industry,which is dominated by pure electric vehicles,and issued a number of subsidies.As the main electrochemical power source of electric vehicles,lithium-ion batteries are one of the most important core technologies of new energy vehicles,temperature has a great influence on the performance of power batteries.Too high or low temperatures will cause rapid decay of battery capacity and rapid decline of charge-discharge cycle life.Therefore,an efficient thermal management system needs to be introduced to regulate the battery temperature.Based on this,this paper uses FLoEFD software to study the heat dissipation characteristics of the mini-channel liquid-cooled battery system.First,the heat generation mechanism of the cell was analyzed,the thermoelectric coupling model of the 40 Ah cell was established by COMSOL software and the simulation was performed under different discharge rates,and then compare it with the cell under the same working conditions.The heat production experiment data is compared to verify the accuracy of the model.This paper researched the temperature characteristics of a certain bottom liquid-cooled battery module,and built physical models of mini-channel liquidcooled battery modules with different connection methods,and then the heat flow field was simulated by FLoEFD.The results show that the cooling performance of the minichannel liquid-cooled system is significantly better than that of the bottom liquid cooling system,and the parallel mini-channel liquid cooling system has the best performance.Compared with the bottom liquid cooling system,the highest temperature and maximum temperature difference of the module can be reduced by 1.9°C and0.94°C respectively under 1C discharge rate.Next,this paper proposed a solution to add a turbulent fluid structure in the flow channel of the mini-channel cold plate to destroy the fluid boundary layer and achieve enhanced heat transfer.And carried out simulation analysis from the two dimensions of turbulent fluid arrangement and structural parameters,and range analysis through orthogonal experiment was performed too.The results show that at a discharge rate of3 C,the highest temperature and maximum temperature difference of the modules in the original scheme can be reduced by 0.75°C and 0.41°C respectively,after adding 5spoilers uniformly in each flow channel.Through the analysis of the influence trend graph,the sensitivity of each structural parameter of the disturbing fluid to the enhanced heat transfer performance is obtained,and on this basis,the best combination of fluid turbulence structure parameters is obtained.Finally,this paper applied the optimal disturbance fluid structure scheme to the mini-channel liquid-cooled power battery system,and then conducted research on its thermal equilibrium performance under different discharge rates,different coolant inlet flow rates,different coolant inlet temperatures and ambient temperatures.The simulation results show that the highest temperature of the power battery system can be controlled in 41.66℃ and the average maximum temperature difference of the cells in the system is 0.93℃ under the discharge rate of 3C,so the thermal equilibrium performance meets the needs of use.