Thermal management of high-discharge lithium-ion prismatic cells using various dielectric nanofluid-based novel immersion cooling design

Immersion cooling is gaining attention as it does not involve complex flow channels within the battery, making it easier to manufacture a compact battery thermal management system for high-discharge prismatic cells. A novel immersion cooling domain with v-shaped fins and dielectric fluids such as deionized water, Novec 7200, and n-heptane as coolants as a continuous phase with Al₂O₃ nanoparticles as dispersed phase using a two-phase mixture model are compared at high-discharge rates of 3C and 5C for the same mass flow rate and coolant volume. V-shape fins considerably reduced the battery’s maximum temperature and improved the cell temperature homogeneity owing to secondary flow and better fluid mixing. Compared to the no-fin case, a maximum temperature reduction of 5 K and 9 K is obtained with deionized water nanofluid at 3C and 5C, respectively. The highest temperature homogeneity of less than 0.5 K is obtained with Novec 7200, even for a higher discharge rate (5C). Using deionized water resulted in a lower maximum temperature rise among the various dielectric fluids, and Novec 7200 reported better temperature homogeneity. Cooling performance improvement with nanofluid is obtained with negligible pumping power compared to the power output delivered by the battery pack.