Experimental study of serpentine channels immersion cooling for lithium-ion battery thermal management using single-phase dielectric fluid

Thermal runaway poses a challenge during the operation of lithium-ion batteries, primarily attributed to the high C-rate charge/discharge processes inherent in Li-ion batteries. This phenomenon induces a temperature elevation response resulting from the internal heat generation during usage. For safe and efficient operation, Li-ion batteries need to be equipped with a battery thermal management system to maintain an optimal temperature range of 15–35 °C and temperature uniformity of each 0–5 °C, thus extending their service life. This study applied the immersion method with HFE-7100 dielectric fluid in serpentine channel immersion cooling for LFP 18650 battery packs. Depth of discharge was carried out at 80 of the battery capacity during the discharge process with variations in C-rate 1C, 1.5C, and 2C. The analysis compares the characteristics of static flow-based immersion (SFI) and dynamic flow-based immersion (DFI) with natural convection (NC). The findings indicate that the NC method exhibits surface temperature characteristics in a descending order when employing the channel arrangement 6-3-2-4-5-1, in contrast to the SFI and DFI methods using 6-5-4-3-2-1. In the discharge process, the heat transfer coefficient for volume flow rates of 0.5 LPM, 1 LPM, and 1.5 LPM at a discharge rate of 2C is determined as 599.0 W/m2·K, 789.1 W/m2·K, and 954.7 W/m2·K, respectively. In this analysis for the lower discharge rates, elevating the volume flow rate leads to heightened heat transfer coefficients and increased heat absorption values, consequently mitigating the temperature rise on the battery surface. Notably, at a volume flow rate of 1 LPM, there exists a discernible ratio between heat absorbed and temperature reduction at 1C through 2C in comparison to the associated pump work. © 2024 Elsevier Ltd