Heat Dissipation Structure Design And Performance Optimization Of Liquid Cooling System For Power Battery Of Electric Vehicle

The rational use of transportation resources and environmental pollution have gradually become the main challenges facing the world since industrialization that we have to face already.Both of them influence each other and work together with local environmental pollution and the greenhouse effect.Therefore,all over the world draw a conclusion that all the countries must change the kind of transportation energy.The national economy is promoted by automobile industry.Since 2009,the Chinese production and sales of automobile have been the NO.1 in the world.As the power of electric vehicles,batteries are prone to thermal problem or even explosions when the battery temperature is too high.The safety issues of battery have become one of the important direction of electric vehicles.However,in addition to the battery pack,the electric vehicle requires thermal management in the passenger compartment,electric motor,and motor controller.The thermal management system will change the safety and efficiency of the electric vehicle.Therefore,it is necessary to establish a complete thermal management system for components such as battery packs and passenger compartments,and to ensure that each component works within a safe range with high economic efficiency.This paper focuses on 3D and 1D simulation and experiment,which regard the heat generation and transformation of the battery pack as the main clue.This essay research the optimization of the heat dissipation structure of the battery pack and vehicle thermal management system.Adding control strategy to the module of the vehicle.The specific study is as follows:1.Considering the battery’s heat generation,working principle and basic theoretical knowledge of computational fluid dynamics,this essay studies the battery’s temperature under three kinds of discharge rates,including 1C,1.5C and 2C with natural convection conditions.Comparing the results of simulation and experiment,the consequence will simplify the simulation of battery module.At the same time,it will lay the foundation of cooling plate on the next step.2.In response to the heat dissipation requirements of the battery module,a cooling plate containing a cooling channel is designed at the bottom of the battery module.A stable heat flux is added to one side of the cooling plate to simulate the heat transferred from battery to the cooling plate.The highest temperature and the average temperature is regarded as the evaluation indicators.Taking the number of inlets and outlets of the cooling plate,the wall thickness,and the channel aspect ratio are three independent factors.According to the optimal parameters under a single factor,with the highest temperature and the lowest average temperature as the goal,orthogonal experiments are carried out on the results under the crossing of different factors,and the optimal parameter combination under multiple factors is obtained.3.For the vehicle thermal management system,three different cooling methods are studied:battery pack considering no thermal management,radiator cooling circuit cooling,and air conditioning cooling circuit cooling.The maximum working temperature of the battery pack sets 58℃ as the limitation.When there is no thermal management,the battery pack reaches the limit temperature in the test and simulation results under high environment temperature conditions.When the radiator cooling circuit management the battery pack,it also cannot meet the cooling requirements.The air-conditioning cooling system is further added to conduct thermal management under extreme conditions.After parameter setting,simulation is carried out.The results show that the air-conditioning system can meet the temperature requirements of the battery pack.In order to improve the working efficiency of the air conditioning cooling system,a PI control model is added to the air conditioning.COP is used as the evaluation index to study the influence of different target temperatures on the COP of the air conditioning cooling system in the PI control model.The research results show that the design of the cooling plate can improve the cooling capacity of the battery pack.The vehicle thermal management system not only improving the energy efficiency of electric vehicles but also meeting the temperature of the battery pack and the passenger compartment,which will increase the range of car.