| In this paper,the square lithium iron phosphate power battery is taken as the research object.The temperature field of the single battery and the heat dissipation of the battery pack are mainly studied by the method of simulation,and the heat dissipation structure of the power lithium battery pack is optimized to significantly improve the heat dissipation effect and thermal stability of the lithium iron phosphate power battery.In addition,a compound cooling device is designed,which combines liquid cooling and phase change material cooling to optimize the cooling performance of power lithium battery.The main research work of this paper is as follows:1.The structure and grid model of power lithium battery cell and battery pack are established.The thermal characteristics of power lithium battery cell are simulated based on the discharge rate of 1C,2C and 3C.The calculated results are basically consistent with the existing experimental results.The control variable method is used to simulate and analyze the heat generation and heat dissipation of the power lithium battery under different ambient temperature and different convection intensity,as well as different coolant inlet speed,different initial coolant temperature and different coolant concentration.The results show that reducing the ambient temperature and increasing the convective intensity can effectively inhibit the temperature rise of the power lithium battery.The faster inlet speed of the coolant,the lower initial cooling temperature and the lower concentration of the coolant can reduce the temperature of the power lithium battery,which provides a certain reference value for the practical engineering application of the heat generation of the power lithium battery and the heat dissipation of the battery pack.2.Optimize the design of the direct contact liquid cooling model of the power lithium battery,change the wall of the smooth battery box to the rib wall,and study the influence of the thermal performance of the power lithium battery with the height of the rib.The results show that with the increase of rib height from 0 mm to 10 mm,the average Nusselt number on the surface of power lithium battery also increases from 121.8 to 195.2,and the heat transfer effect is obviously enhanced.The maximum temperature and the maximum temperature difference on the surface of power lithium battery are reduced by 13.1 ? and 12.7 ?,respectively,with a decrease of 30% and 74.3% respectively.3.Design and invent a power lithium battery composite heat sink,which is based on liquid cooling and phase change material cooling.The single liquid cooling mode can not meet the uniformity of the heat dissipation of the battery.The lithium battery near the coolant inlet has a good heat dissipation effect,while the cooling effect at the coolant outlet is not good.Therefore,the device combines the liquid cooling module and the phase change material cooling module to indirectly contact the liquid cooling module to cool the power lithium battery on both sides,while the phase change material cooling module is to the center The location of the power lithium battery to implement cooling,combined with the two cooling advantages and make up for their own shortcomings,so that the lithium battery cooling performance to achieve optimization,the invention has applied for a national patent. |
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