| Temperature has a great impact on battery performance and life.As far as the current technology is concerned,it is not possible for the battery to maintain high performance over a wide range of temperature.Therefore,it is very necessary to control the battery temperature within the optimal operating temperature range by using the battery thermal management system(BTMS).Based on this,a scheme of BTMS for liquid direct contact battery was presented in this paper.The BTMS was studied and designed by means of theoretical analysis,numerical calculation and experimental verification.The main tasks are as follows:(1)Target battery was tested by charge and discharge test,according to the capacity dimension,resistance dimension,discharge voltage dimension and life dimension of the battery,the optimum operating temperature range of the battery was 15℃~40℃.The necessity of the BTMS was obtained by analyzing the difference between the actual operating temperature range and the optimal operating temperature range of the battery.Based on this,the target performance of the BTMS was determined,the structure and principle of the BTMS were explained in detail.(2)Based on computational fluid dynamics and heat transfer,the thermal model of single cell was established.The temperature field of the battery under constant rate discharge was simulated.The simulation results were consistent with the experimental results.The maximum error between the two was less than 7%.It was proved that the thermal model of the battery was reliable.At the same time,in order to better simulate the heat generation of the battery in the actual use of the automobile.The heat generation model of the battery based on NEDC and UDDS were established,and the instantaneous heat generation of the battery was obtained,which laid a foundation for the simulation and analysis of the battery pack.(3)In this paper,three different types of channel structures,namely,top parallel "U" channel,bottom parallel "U" channel and high-low interlaced "U" flow channel,were proposed and the fluid-solid coupling models of the corresponding structures were established.The simulation results show that the high-low interlaced "U" channel structure has better heat dissipation and heating effect than the parallel "U" type channel structure.Therefore,the high-low interlaced "U" structure was chosen as the structure form in this paper.the heat dissipation,heating and heat preservation effects of the battery pack were simulated and analyzed,The optimum flow rate of heat dissipation and heating was determined to be 1.0 m/s,heating power was 500 W,the insulation material was silica aerogel,and the thickness of insulation layer was 10 mm.(4)On the basis of simulation and analysis,the calculation of the key parts of the BTMS were completed,the structure of the BTMS was designed,the functional prototype of the BTMS was processed,the control strategy of the BTMS was formulated,and the program model of the thermal management control system was built.Finally,the BTMS of direct contact battery based on liquid was tested.The results showed that the BTMS has good heat dissipation,heating and heat preservation performance,and the experimental results were basically consistent with the simulation results. |
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