Numerical Simulations for Lithium-Ion Battery Pack Cooled by Different Minichannel Cold Plate Arrangements

In real electric vehicles, the arrangement of liquid-cooled plates not only influences the thermal performance of the battery pack but also relates to the energy consumption of the BTMS and the compactness of the whole battery pack. In this study, design A, design B, design C, and design D, a total of four different arrangement designs of battery thermal management based on liquid-cooled plates with microchannels, are proposed for a 35 V battery pack composed of 12 LiFePO4 pouch battery cells connected in series, and the corresponding three-dimensional electrical-thermal-fluid model is established for numerical study. The cooling effects of the four designs are discussed and compared in terms of discharge rate, contact thermal resistance, and external short circuit. For design D, cold plates are placed in front of each battery cell. The results show that design D achieves the best cooling effect with the lowest power consumption compared to the other three designs under 0.5C, 1.0C, and 2.0C discharge rate. Its maximum temperature is about 30 degrees C, and maximum temperature difference is under 5 degrees C. The reduction in contact thermal resistance has different effects and magnitudes for different designs with different cold plate arrangements, but the overall effect is small. In the extreme condition of external short circuit, for design D, increasing the mass flow rate can reduce the maximum temperature of design D from 76.6 degrees C by 27.5% to 55.5 degrees C and the temperature difference from 35.0 degrees C by 23.4% to 26.8 degrees C. Selecting the proper coolant flow rate can keep the maximum temperature and temperature gradient on the battery pack of design D within tolerable level, and increasing the flow rate helps to enhance the cooling effect. For the other three designs, the maximum temperatures and temperature gradients exceeded 90 degrees C and 40 degrees C under the external short circuit condition, and increasing the flow rate has very little effect on the performance enhancement.