| Developing new energy vehicles is a necessary path for China to transform from a massive consumption country to a leading automotive manufacturer.Power batteries are one of the core components of new energy vehicles.Due to their high voltage,high specific energy,long cycle life and no pollution,lithium ion batteries are widely used in new energy vehicle power battery packs.When the power battery pack is working,a large amount of heat will be generated inside the lithium ion battery.If the temperature of the battery pack is too high,it is easy to cause irreversible damage to the battery,and even safety accidents such as combustion and explosion may occur.Therefore,the heat dissipation problem of the power battery pack is still restricting the development of new energy vehicles.This article was focused on the research of the liquid-cooled heat dissipation structure and optimization of lithium power battery packs.The main research contents are as follows:(1)Firstly,the 18650 lithium ion battery was taken as the research object,and the internal resistance and surface temperature of the battery were measured by experiments when the battery was discharged at a rate of 1C and 2C;Secondly,the heat generation rate of a single battery under different discharge conditions was obtained by experimental data and the Bernardi battery heat generation rate model;Finally,the 18650 lithium ion battery of cell 3D model was established and CFD simulation was performed.The accuracy of the 3D simulation model of model 18650 lithium ion battery was verified by comparing the experiment and simulation results.(2)Taking an FSEC power battery pack as the research object,an active and indirect contact liquid cooling and heat management system was designed for the battery pack meanwhile CFD thermal simulation analysis was performed.It was found that the maximum and minimum temperature deviation between the modules of the power battery pack were less than 0.1℃,and the temperature uniformity between the modules was perfect;under 2C rate discharged conditions,the internal battery temperature difference for the battery pack is greater than 5℃,which was higher than the index therefore it was necessary to optimize the current liquid-cooled flow channel structure;the flow of the cooling fluid of each module in the battery pack was relatively uniform,and the total pressure drop at the inlet and outlet of the battery pack was about 989 pa.(3)Using the multi-objective optimization method based on DOE to establish an agent model to optimize the flow channel structure parameters and pump flow matching of the self-designed power battery pack,it was required that when the battery pack was discharged at the 2C rate,the battery pack indicators could also be controlled within the design requirements.The results shows that: By the multi-objective optimization method based on DOE to establish the agent model,the maximum error between the optimization results within the feasible variable interval and the CFD simulation results was only 1.8%,which indicated the accuracy of the method;comparing the original battery pack with the optimized liquid cold structure,the maximum temperature difference of the battery pack decreased by 7.1%,and the pressure drop at the inlet and outlet of the battery pack decreased by 15.77%,under the condition that the contact angle between the battery and the liquidcooled runner increased by 40% and the flow rate decreased by 10.6%,.The final optimization results met the design indexes.Using the data mining method to explore the relationship between optimization variables and targets,it was found that the coolant flow rate was the main factor affecting the internal temperature difference and pressure drop of the battery pack.In this paper,the liquid-cooled heat dissipation of lithium-ion power battery packs was studied.We designed a set of liquid-cooled channel with simple structure and good heat dissipation effect.Besides multi-objective intelligent optimization algorithm was conducted to optimize the parameters to meet the thermal management needs of the power pack.The research content has a certain significant in power battery liquid-cooled port structure optimization. |
PDF Full Text Request