Thermal performance analysis and experimental verification of lithium-ion batteries for electric vehicle applications through optimized inclined mini-channels

Power units (i.e., batteries) of electric vehicles (EVs) generate heat while being charged or discharged, which deteriorates their performance and reliability over time. This paper investigates a comprehensive spectrum of geometric and thermo-fluidic parameters of a liquid coolant flowing through mini-channels. These are embedded in the surface of an EV battery to curtail overheating. Design parameters such as aspect ratio and angular orientation of the mini-channels were varied randomly to investigate several geometric configurations that are scarcely intuitive. The coolant mass flow rate and the fluid inlet temperature were also varied through a large dataset of randomly distributed values. A real-time EV driving cycle was implemented alongside an experi-mentally validated model to evaluate the battery operation, which evidenced the complex dependence of the battery's thermal state with different levels of cooling retrofitting. The study also analyzed the parasitic power consumption arising from the pumping and cooling energy demands to drive the coolant system to achieve an optimally designed retrofit for a reliable battery performance. It was found that the mini-channel parameters considerably affect the thermal performance of the battery. However, the optimized case was found to have a minimum temperature difference in the battery and a minimum power requirement. The case with a fluid inlet velocity of 0.13 m/s, a fluid inlet temperature of 312.9 K, an aspect ratio of 1.7, and an inclination angle of 4.9 degrees was found to be the most suitable, leading to a refrigeration power requirement of 0.85 W only. The battery temperature after the end of the driving cycle was maintained at 313 K.