| Cars have become the main means of transportation for people,but with the increase of the number of cars,the pollution to the environment is becoming more and more serious.The emergence of electric cars is changing this situation,because electric cars will not pollute the environment because of exhaust emissions.The power of electric vehicles is provided by the power battery pack,but the power battery will generate a lot of heat when discharging at a high rate,which will increase the temperature of the battery pack and have a great impact on the service performance,safety performance and working life of the power battery.The temperature rise and local temperature difference of the battery pack are the key factors affecting the working efficiency of the battery pack.The temperature of the power battery pack can be maintained within the normal operating range of the battery,which has a very important impact on improving the performance of electric vehicles and extending the battery life.In order to ensure the stable and efficient work of the power battery,the power battery thermal management technology is required to reasonably control the temperature of the battery.In this paper,the rules of heat generation and heat transfer of lithium ion power batteries are analyzed,and 18650 lithium ion battery is selected as the research object.Through numerical simulation,the cooling effect of the air cooling system of the battery pack composed of this type of battery is studied and optimized.The main work and conclusions of this paper are as follows:(1)The thermal generation mechanism and thermal model of power batteries are described,and the thermal management system of battery packs is studied.Referring to the common power batteries of different types,the 18650 lithium ion battery was finally determined as the research objective,and the optimal temperature range and temperature difference requirements as well as the internal structure,electrochemical reaction principle,heat generation mechanism and heat transfer characteristics of this type of battery were determined.(2)First of all,the influence of the battery arrangement on the battery temperature is explored,and the battery model with different arrangements is simulated and analyzed.The results show that the misplaced battery arrangement has the best heat dissipation effect.(3)The air cold system in order to further improve the heat dissipation effect,this paper designed a battery increase diversion between slabs cooling air diversion effect,and carries on the multiple factors analysis:from the guide plate spacing ratio,spacing,size,area,material aspects of system analysis,it is concluded that the optimal battery cooling model.(4)In the end,the battery box was optimized and analyzed to obtain the structure size of the box with the best heat dissipation effect,and air intakes were added on the side and front of the battery box to improve the cooling performance of the battery heat dissipation system.When the multi-inlet air cooling system is simulated and analyzed under different air inlet flow distribution schemes,the optimization design is carried out from the number of side and front inlet and the Angle of side inlet.Finally,a comprehensive comparison is made between two ways of increasing air inlet at different positions.Results show that when the profile Settings four imported and inclination for two 45 °,90 °,the battery temperature meet the requirements of the battery to normal operating temperature and the consumption of energy consumption is relatively small,the battery cooling system optimum cooling efficiency. |
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