| With the rapid development of global society and economy,traditional fuels are getting depleted and the energy crisis has become a worldwide problem.In order to ensure sustainable social and economic development,automobile manufacturers all over the world are committed to developing new energy vehicles.During the charging and discharging process of the battery,if the temperature rise and temperature uniformity inside the battery cannot be effectively controlled,it will cause the local temperature of the battery pack to be too high,which in turn will lead to the mismatch of the module cell performance and the early failure of individual single cells,affecting the performance of the whole battery pack.In this paper,the LG 18650 battery module heat sink system based on the enhanced thermal conductivity of phase change materials is studied to ensure that the battery module works in the optimal temperature range(293.15K～318.15K)and the maximum temperature difference is less than 5K,with the goal of further reducing its maximum temperature,the phase change material performance of the power battery heat sink system is investigated,and the latent heat value,the thermal conductivity and the subcooling degree of the phase change material are used as the basis.The feasibility of the best composite phase change material to improve the heat dissipation performance of the power battery module is verified through simulation and experimental comparative analysis,using the latent heat value,thermal conductivity and subcooling degree of the phase change material as evaluation indexes.(1)Analyze the structure of LG18650 lithium-ion battery and explore its working mechanism to clarify the heat production characteristics and heat transfer mechanism;determine the internal resistance of the battery with an internal resistance tester;solve the heat production value of LG 18650 lithium-ion battery under the discharge rate of 1C,2C and 3C according to Bernardi’s heat generation rate model;finally solve the thermal property parameters of the battery to pave the way for the later research contents.(2)A combination of several inexpensive and readily available high thermal conductivity additives was added to PW to improve its thermal conductivity,and the thermophysical parameters of the composite phase change material were compared and analyzed to obtain the composite phase change material with the best comprehensive performance;the study showed that EG20-CF20/PW ternary composite phase change material has the best comprehensive performance in this study,which lays the foundation for the simulation and experiment in the following.(3)Simplify the battery model,establish the geometric and mathematical model of the Li-ion power battery module,and carry out the mesh division and the simulation analysis,and verify the enhanced heat dissipation of the battery based on the EG20CF20/PW ternary composite phase change material heat dissipation system by taking the highest temperature and temperature difference of the battery unit and module as the evaluation index according to the temperature cloud diagram of the battery unit and module after simulation.The feasibility of the EG20-CF20/PW ternary composite phase change material heat dissipation system is verified.(4)A power battery heat dissipation experimental platform was built to verify the feasibility of strengthening the heat dissipation of the battery based on the EG20CF20/PW ternary composite phase change material heat dissipation system.The experimental results show that the temperature values of each single battery obtained from the experiment and simulation are basically the same,and the overall change trend is consistent.,the rationality and feasibility of thermal management of battery modules,and has good engineering application prospects. |
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