Research On Thermal Management Technology Of Lithium-Ion Batteries Based On Combination Of Phase Change Materials And Liquid Cooling

The two major problems of environmental pollution and energy shortage are becoming more and more serious.New energy vehicles represented by electric vehicles have developed as the times require.The most widely used lithium-ion battery is the core component of electric vehicles.Its energy density is constantly increasing,but the battery’s heat output is also increasing.Whether the lithium-ion battery has sufficient heat dissipation and whether the temperature distribution is uniform will directly affect the battery’s cycle life,use efficiency and operating safety.Compared with traditional battery cooling methods such as air cooling,liquid cooling,and heat pipe,phase change materials have the characteristics of phase change constant temperature and heat absorption,and do not require additional pumping.It has a better temperature control and temperature equalization effect on the battery pack.However,due to the limited latent heat of phase change materials,there are certain limitations in some severe working conditions.Therefore,the composite battery thermal management technology combining phase change materials with active cooling methods such as liquid cooling has important research significance.This article takes 3 * 5 15 series 18650 lithium-ion battery modules as the research object.The main research content is based on the phase change material battery module heat dissipation simulation analysis and experimental verification,and the optimal design of a new phase change material combined with liquid cooling Battery Thermal Management Cooling Solution.In the specific research process,this paper analyzes the structure,principle and heat generation mechanism of lithium ion batteries,and then obtains the heat generation rate of the single cell at different ambient temperatures and SOC values.After managing the selection requirements in the application,a paraffinexpanded graphite composite phase change material was selected and prepared,and the amount of phase change material was estimated according to the heat dissipation requirements.The mathematical model of lithium ion battery phase change cooling was explored based on theoretical analysis.The effect of phase change cooling of lithium ion battery modules was analyzed using Fluent simulation.The reliability of the simulation model and results was verified by experiments.Then,the effects of the melting point,thermal conductivity and latent heat of the phase change material on the heat dissipation of the battery module were analyzed through simulation,and the best thermal and physical parameters of the phase change material were obtained,thereby completing the selection and matching of the phase change material in the battery thermal management..Aiming at the problem that the phase change material cannot be further radiated to the battery module after it is completely melted,the phase change material is combined with liquid cooling,and the influence of the cooling liquid flow and temperature on the heat dissipation effect is analyzed.There are two structural optimization schemes for the liquid pipeline and the liquid pipeline.The research shows that the optimization scheme of the embedded liquid pipeline has better heat dissipation and temperature equalization effect of the battery module than the solution of the embedded thermal conductive rod.Aiming at the problem of low utilization of phase change materials,a switch-type coolant flow control strategy is set with the maximum temperature of the battery module as the threshold temperature of the liquid cooling system.Studies show that when the temperature threshold is set to 42 ° C,the battery module filled phase change material has better heat dissipation and temperature uniformity than thermally conductive silicone,and the energy consumption of the phase change-liquid cooling composite thermal management system can be reduced by 17.4%.The research in this article has certain guiding significance for the thermal management design of composite batteries based on the combination of phase change materials and liquid cooling,especially the selection and matching of phase change materials,and the thermal management structure and control of phase change-liquid cooling composite batteries.The design of the strategy provides an effective solution.