Research On Thermal Management Of Li-ion Battery Based On Air-cooling-phase Change Material Coupling

With the acceleration of modernization,automobiles become a common tool for every household,and the automobile industry is booming as a result,with record high annual automobile production.However,traditional automobiles consume large amounts of nonrenewable resources such as petroleum and emit large amounts of harmful vehicle exhaust,increasing the dependence on non-renewable resources and seriously polluting the natural environment.In recent years,with the emergence of environmental and energy crises,countries have invested more resources in the research and development of environmentally friendly and energy-saving electric vehicles.Power battery is an important part of electric new energy vehicles.Among many types of power batteries,lithium-ion battery is greatly favored because of advantages of high voltage platform,high energy density and no pollution to the environment.When the lithium-ion battery pack is in normal operation,the working performance and life are greatly affected by temperature.When the temperature of the battery exceeds the optimal working temperature range,the battery performance will be significantly reduced,the battery life will be shortened,and even safety accidents will occur.Therefore,it is very necessary to ensure that the operating temperature of lithium-ion battery pack is in the appropriate temperature range.In this paper,mainly focusing on the cylindrical18650 Li-ion battery pack used in the mainstream of today’s electric vehicles,and design the thermal management scheme of Li-ion battery based on air-cooling-phase change material coupling through a combination of theory,simulation and experiment,and the main research contents are as follows:Firstly,the mathematical model of phase change material heat dissipation for single-cell Liion battery is established,and the theoretical working cycle equation of single-cell Li-ion battery is derived;the simulation analysis of phase change material heat dissipation for single-cell Li-ion battery is conducted using FLUENT software to verify the accuracy of the theoretical working cycle equation;the corresponding experimental platform is built to verify the theoretical working cycle equation of the battery in comparison with the theory.Secondly,the heat dissipation effect of traditional phase change material heat dissipation for Li-ion battery pack is analyzed for Li-ion battery pack module;the thermal management scheme of Li-ion battery based on air-cooling-phase change material coupling is proposed for the maximum temperature and temperature difference of the battery pack;the phase change material configuration problem in the thermal management scheme is studied and optimized using Isight software;then the design is combined with air-cooling,and the effect of Li-ion battery module inlet air velocity,position and radius on the heat dissipation of the battery pack.The results show that the air-cooling-phase change material coupled thermal management scheme for Li-ion battery can effectively reduce the maximum temperature and temperature difference of the battery pack.Finally,for the problem of temperature difference of Li-ion battery pack,the design scheme of Li-ion battery thermal management based on multi-port air-cooling-phase change material coupling is proposed;the effect of various inlet and outlet distribution methods on the temperature difference of the battery pack is analyzed by using FLUENT simulation;then the corresponding experimental platform is built and experimentally verified.The results show that the thermal management scheme of multi-port air-cooling-phase change material coupling lithium-ion battery at the same time point slows down the temperature rise of the battery pack significantly compared with the single-port scheme,and the maximum temperature and temperature difference of the battery pack are reduced by more than 5℃.