Research On Cooling And Heat Preservation Of Electric Vehicle Battery Pack With Thermal Storage Structure

In order to promote the development of new energy vehicles,all countries in the world have issued a series of policies to expand new energy vehicles and replace traditional internal combustion vehicles.Power battery pack,one of the core component of electric vehicles,directly impacts the development of EV.The effect of power battery pack cooling and thermal insulation directly affects its performance,service life,reliability and safety.Therefore,there is a necessary for efficient thermal management of EV battery packs to make the battery operate within the optimum temperature range and uniform battery pack temperature.Based on the research and application status of power battery thermal management system,the advantages and disadvantages of common cooling methods are analyzed,and a new type of cooling and heat preservation of EV battery pack with thermal storage structure is designed.The structure comprise battery cells,a cooling structure,heat conducting structures and a thermal storage structure.When the battery is in the working state,the cooling structure among the battery cells cools the battery pack.A part of the heat is transferred to the thermal storage structure via the heat conducting structures for storage.And the other part of the heat is transferred to the environment via the boundary.When the battery stops working,the heat in the thermal storage structure is released,which serves as a thermal insulation to maintain the temperature of the battery.Based on the analysis of the basic structure and heat generation mechanism of 18650 lithium iron phosphate battery,the heat generation rate of the battery was determined.And the physical parameters of the lithium ion battery and the material used in the module were determined.This paper mainly uses the simulation method to study the cooling and thermal insulation effects of the designed model.First of all,the reliability of the numerical simulation method used in this paper is verified by literature experimental data.Secondly,the different parameters in the model are simulated by fluent,such as he battery spacing,the diameter of the thermal structures,the distribution of the thermal structures,the thermal structures materials,the thickness of the thermal storage structure,the location of the thermal storage structure.By analyzing the influence of different parameters of the module to cooling effect,the distribution and size of the module structure are optimized to obtain the battery module with thermal storage structure overhead and the battery module with thermal storage structure lateral.The battery module with thermal storage structure lateral is more suitable for large commercial EV.The battery module with thermal storage structure overhead have a wider range of applications.The cooling and thermal insulation of battery module with thermal storage structure in the winter and summer were simulated.Under the normal operating power of the battery pack,the battery module with thermal storage structure could effectively control the average temperature of the battery and the ideal temperature difference between the battery cells.In order to further improve the cooling effect under high power,a certain number of fins are installed on the outside of the heat storage structure.By comparison result with and without fins,the battery model with the fins can be used to effectively manage the battery pack under high power.