Enhancing energy and thermal efficiency of single-phase liquid immersion cooling systems for lithium-ion batteries in electric vehicles
Abdul Wahab, Noel Cifterler, Nima Amjady, Abhijit Date, Hans Kemper, Hamid Khayyam
Abstract
Electrifying nonroad mobile machinery requires a high-power energy storage system capable of fast charging and discharging of lithium-ion batteries to meet the operation demands. This necessitates an effective battery thermal management system to dissipate extensive heat generation at higher C-rates. This study employs a single-phase immersion cooling strategy to evaluate the heat dissipation in LiFePO 4 batteries at discharge rates of up to 8C. A pseudo-three-dimensional coupled electrochemical-thermal model is utilized to analyze non-uniform temperature variations, providing a comprehensive assessment of thermal behavior. A high-fidelity multiphysics model is developed for the immersion-cooled battery pack, which emerges as a promising cooling technology for extending battery lifespan and ensuring the safety and reliability of electrified vehicles under diverse operating conditions. Structural and flow optimization further enhances the temperature uniformity of the battery pack within 5 °C and lowers the maximum temperature from 330.71 K to 306.41 K at a high discharge rate of 8C, mitigating localized hot spots. The study further analyzes the thermal influence of battery connectors, busbars, and holders, which contribute to heat buildup due to resistive losses and significantly affect convective heat transfer in immersion cooling. A global sensitivity analysis is also performed to identify the most influential thermophysical properties of dielectric fluid affecting heat transfer in battery immersion cooling. This study demonstrates that optimized forced immersion cooling improves thermal performance by enhancing thermal uniformity by 47.7 %, ensuring safe and efficient battery pack operation for high-power applications. • Optimized single-phase immersion cooling enhances energy and thermal efficiency • Structural and flow optimizations achieve optimal thermal uniformity at high C-rates • Influential thermophysical properties of dielectric fluid identified via sensitivity analysis • Thermal impacts of battery connectors, busbars, and holders quantified in immersion cooling