Design And Simulation Analysis Of Liquid Cooling Structure Of Pure Electric Vehicle Based On CFD

In recent years,due to the increasing emissions of carbon monoxide,carbon dioxide and other greenhouse gases,the living environment of human beings began to deteriorate day by day,more and more people began to choose electric vehicles as transportation and alternative means.As the energy storage component,the power battery pack is the core part of the electric vehicle,and its performance directly affects the endurance performance and safety performance of the electric vehicle.A lot of heat will be produced in the battery part of the electric vehicle due to the energy release during the working process.If not dissipated in time,the temperature of the whole battery module will rise,resulting in the decline of battery life and performance,even fire,explosion and other safety accidents.Therefore,the study of efficient and stable cooling system will play an important role in the safety of battery pack.In this paper,the liquid cooling system of a light pure electric logistics vehicle will be studied,mainly on the battery module design,cooling wall structure design optimization and other issues.Firstly this paper studies the single lithium battery,analyzes its structural characteristics,heat generation mechanism and heat generation mechanism,conducts the internal resistance test and temperature rise test of the single battery,and establishes the heat generation model of the single battery.Through the combination of simulation and test,the accuracy of the heat generation model and the accuracy of various parameters are verified,which provides the research basis for the battery group design.Secondly,according to the capacity of 21700 batteries,the whole module and the capacity of a single battery are designed in series and parallel,and the cooling wall structure of the cooling system is designed according to the size of 21700 batteries and the number of batteries in a single battery.The structures and sizes of cooling walls,such as square groove,U-shaped,double ring and snake shaped,are designed.Because the heat transfer of the cooling system is a conjugate heat transfer method,which involves the heat transfer of two coupled fields,this paper studies the simulation analysis of several cooling wall heat transfer structures based on the principle of computational fluid dynamics.From the aspects of heat dissipation,flow velocity distribution uniformity,flow channel pressure loss and so on,a serpentine cooling wall structure was selected and its structure was improved.A serpentine cooling wall with small angle and double enveloping was obtained to control its temperature difference and pressure loss.Finally,this paper analyzes the influence of different cooling factors on the cooling effect of the structure.It is concluded that the larger the flow rate is,the better the cooling effect will be when only changing the flow rate at the inlet of the cooling wall,and the smaller the influence on the cooling effect will be when the flow rate increases beyond a certain range;the temperature of the coolant flowing into the pipe wall should be close to the ambient temperature,so as to ensure the uniformity of the temperature field of the battery after cooling;increase the inlet of the cooling wall When the number of channels is less than 4,the uneven heat dissipation of the cell is obvious;when the inlet flow rate is constant,increasing the inlet section size will increase the coolant flow rate in the tube wall and improve the cooling effect.