Thermal Aimulation Analysis And Research Of Power Battery Pack Based On CFD

Driven by national policies,the new energy vehicle industry is entering a stage of vigorous development,and pure electric vehicles and hybrid electric vehicles are entering the automobile market in a big way.As its core power source,the safety and stability of the power battery pack are important indicators to measure the performance of electric vehicles.Because the power battery is extremely sensitive to temperature changes,too high temperature and too low temperature will affect the safety and life of the battery.Therefore,the thermal management system of the power battery is studied,and a reasonable and efficient cooling and heat dissipation structure is designed to make the temperature of the battery suitable and stable,so as to prevent the danger of the battery temperature due to the drastic change of the battery temperature during the driving of electric vehicles.This paper adopts numerical simulation and theoretical analysis methods,mainly focusing on the analysis and research of battery pack and cooling channel design.Firstly,the category,structure and working mechanism of lithium batteries in the emerging market are summarized,and the thermal model of the battery is constructed under the guidance of heat production theory and heat transfer mechanism,and the required thermophysical parameters are calculated.Then,the CFD software STARCCM+is used to simulate and calculate,and it is found that the thermal state of the battery is more reasonable under the conditions of low rate,normal temperature and high heat transfer coefficient.Secondly,on the basis of the battery cell pack,three new liquid-cooled runner structures are designed,and the performance of the three is comprehensively evaluated from coolant filling rate,temperature control,temperature uniformity,pressure drop loss,flow rate distribution,heat flux and energy saving by combining VOF simulation and fluid-structure interaction simulation.Through comparative analysis,it is found that although the uniform fin-shaped structure performs well in pressure drop loss,its flow rate is uneven,and the temperature control of the battery module is insufficient.The curved "wang" runner structure and the interactive "gong" runner structure meet the design requirements in all aspects,and the heat dissipation effect is the best under the curved "wang" runner structure: the coolant can be filled with a liquid-cooled runner within 18 seconds,the coolant flow rate is uniform,the maximum temperature of the battery pack can be reduced to below 32 °C under high temperature conditions,the temperature difference is controlled within 5 °C,the pressure is controlled within30000 Pa,and the pressure drop loss and heat flux are reasonable.Finally,combined with the principle of single variable,the influence of environment,temperature difference between coolant,mass flow,coolant volume concentration and other factors on the heat dissipation effect was analyzed,and it was found that when the ambient temperature and coolant temperature difference was 4~6°C,the heat dissipation effect was the best.The mass flow of coolant has a great influence on the heat dissipation effect,and the expansion of the mass flow rate gradually reduces the temperature rise and maximum temperature difference in the module,but the heat dissipation effect decreases significantly after exceeding 10L/min.The volume concentration of coolant has little effect on the heat dissipation effect of the battery pack,the smaller the volume concentration,the better the liquid cooling heat dissipation effect,but the change range is not drastic,and the appropriate volume concentration adjustment can be made in combination with the actual situation.