Performance investigation of a liquid immersion cooling system with fish-shaped bionic structure for Lithium-ion battery pack

A battery thermal management system (BTMS) is crucial for the safety and performance of lithium-ion batteries (LIBs) in electric vehicles. To improve the BTMS in terms of cooling performance and pumping cost, an innovative liquid immersion battery cooling system (LIBCS) using flow guides with fish-shaped holes is proposed. The design of this flow guide is grounded in conformal mapping technology and bionics principles. An electrochemical-thermal model for the battery module is established by the Multi-Scale Multi-Domain approach with the Newman, Tiedemann, Gu, and Kim model. The simulation and experimental results show good agreement, with mean absolute errors of 0.0174 V, 0.126 degrees C, and 0.042 Pa for LIB voltage, maximum temperature, and average pressure drop, respectively. Furthermore, the effects of four different battery pack structures on the performance of LIBCSs under different operating conditions are investigated. For LIBs at a 3C discharge rate, the LIBCS using common flow guides decreases the maximum LIB temperature by 5.3 % at a mass flow rate of 0.00273 kg/s compared to the without flow guide case, but it increases the pump power consumption by 81.4 %. However, using flow guides with circular holes or fish-shaped holes reduces the maximum LIB temperature by 9.2 % and 12.2 %, respectively, compared to LIBCS using common flow guides, while maintaining maximum temperature differences within 5 degrees C. Interestingly, the LIBCS using flow guides with fish-shaped holes reduces the pump power consumption by 42.1 % and 11.8 %, respectively, compared to the common flow guide and flow guide with circular holes cases under the same operating conditions. Additionally, the comprehensive performance factor of LIBCS using flow guides with fish-shaped holes improves by 24 %, 39.3 % and 7.3 % at a mass flow rate of 0.00273 kg/s, respectively, compared to cases using no flow guide, common flow guides and flow guides with circular holes, indicating greater value for application in practical engineering.