| As people pay more and more attention to renewable energy and environmental protection,new energy vehicles have gradually entered the social arena,and electric vehicles have been pushed to a new height again.Electric vehicle runs quietly,smoothly and has no emission.However,the popularization of electric vehicle was still restricted by several vital technologies of power battery.One of them is the thermal management of power battery.Because of the special working conditions,power batteries often need to be charged and discharged at a high rate.The heating rate of the batteries fluctuates greatly and is prone to thermal runaway.When the temperature of power batteries is at a high level,the phenomena of battery capacity will decrease,and internal resistance will increase,even fire and explosion accidents may occur,which seriously affects the reliability and safety of power batteries in our life.Therefore,in order to control the working temperature of power batteries within a suitable range,it is necessary to focus on electric steam.A perfect,reliable and efficient thermal management system for power batteries need to establish when electric vehicle is working.A company's lithium iron phosphate battery is taken as an object,according to the relevant national standards,simulation analysis was used to study the battery,the power battery module and its cooling plate.The main work done is as follows:(1)Through the analysis of literature,the research status of thermal management of lithium battery modules at home and abroad was studied,and the cooling methods of battery modules commonly used in the market were compared and summarized.(2)Secondly,the mechanism and heat transfer characteristics of lithium batteries are analyzed,and the cell heat generation model of lithium batteries is established.(3)Using the Boussinesq hypothesis and fluent to simulate the cell in natural convection conditions,the error of results between the simulation and the test is less than 5%,which proves the accuracy of the battery model.At the same time,the natural convection analysis of cell at different temperatures shows that cooling measures should be taken in the use of the lithium battery.(4)Battery standard module and cooling plate are designed according to national standards.Four battery module schemes are screened by orthogonal experimental design method.After obtaining the optimal configuration parameters in each scheme,the advantages and disadvantages of each scheme are compared and the optimal scheme ? is selected.The accuracy of the model is verified by comparing the theoretical calculation of fluid temperature rise with the simulation results.At the same time,it is concluded that the maximum temperature difference of the cooling plate in the optimal scheme ? exceeds the target temperature,which still needs to optimize.(5)The cooling plate of the battery module is Taken as the research object,firstly,parametric geometric modeling is carried out to determine the optimization variables and response values,and the boundary conditions are applied to the cooling plate in the form of UDF heat flux.Then the response surface model is used to optimize the cooling plate.Finally,the model is established by the optimizing dimension for analysis and verification.The comparison shows that the temperature difference of the cooling plate decreases by 9.5%,and the pressure drop decreases by 16.88%.The optimization effect is obvious while the working efficiency of the cooling plate is ensured. |
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