Research And Design Of Liquid Thermal Management System For Electric Vehicle Battery Pack

With the growing energy and environmental problems,electric vehicles as a representative of new energy vehicles,have been everyone's attention.Although the development of new materials and new technologies has brought a variety of new batteries,but still can not make the performance of electric vehicles,manufacturing costs and mileage with the traditional internal combustion engine to compete.The main reason for this is the lithium-ion battery performance and temperature are closely linked.When the temperature is too high,the battery is less safe;when the temperature is too low,the battery reaction rate is low,the battery capacity will be reduced,which life mileage and battery performance will have a serious impact.Therefore,the research on the thermal management system of the battery pack is very necessary to ensure the normal operation of electric vehicles.This article first summarizes the development of electric vehicles,power batteries and development of battery thermal management system.The basic structure,working principle and thermal characteristics of lithium ion battery were studied.The three-dimensional model of single cell was established,and the temperature field simulation was carried out after the battery-related physical parameters were determined.By comparing the experimental data in the relevant literature,and the validity of the model was verified.Through the simulation analysis,the temperature rise of the battery pack at different discharge magnification is studied.A new type of fully immersed liquid flow management system was designed,and the heat transfer medium and its related physical parameters were determined,The influence of the flow rate of the coolant and the wedge angle of the inlet runner on the temperature field distribution of the battery was studied.Studies have shown that the use of liquid as a heat transfer medium,can be a good cooling effect.When the coolant flow rate is 0.2m / s and the wedge angle is 10o,the maximum temperature of the battery pack is 33.91 ? and the temperature difference is 2.40 ?.By adjusting the coolant flow rate and the wedge angle of the inlet runner,the desired cooling effect can be achieved,and using the ADVISOR and FLUNENT simulations to verify that the optimized liquid cooling system also has better cooling effect under typical operating conditions.The effects of different coolant flow rates and different initial temperatures on the heating of the cells were also investigated.Studies have shown that the cooling fluid flow rate of 10 L / min,the battery pack heated to 18 ?,about only 4min,both to achieve the heating effect,but also save energy.On this basis,this paper designs the liquid flow system,and realizes the integration of cooling and heating,and carries on the three-dimensional structure design.At the end of this chapter,the control strategy of cooling and heating system is put forward,which has certain reference value for the research and design of thermal management system of battery pack.