Developing a novel battery thermal management system utilizing supercritical CO₂ as the cooling medium

초록

This study pioneers the utilization of supercritical Carbon Dioxide (sCO2) as a coolant within Battery Thermal Management Systems (BTMSs) designed for cylindrical lithium-ion cells, offering a comprehensive evaluation of its performance compared to conventional coolants. A validated CFD-based numerical approach is employed to analyze the effects of key factors, including the number of cooling units, geometric parameters, and cooling conditions. The SST k-omega model is employed for simulating turbulence, and the variable thermophysical properties of sCO2 are obtained from the NIST REFPROP program, based on the specified ranges of pressure and temperature. The results illustrate that increasing the number of cooling units from 1 to 3 reduces the maximum temperature difference by 17.1 K, but further increasing from 3 to 5 units only slightly improves this parameter by 1.3 K. The cooling channel diameter has little impact on battery module temperature, but increasing the height and pitch of cooling units improves temperature uniformity. Compared to deionized-water, engine-oil, and ethylene-glycol, sCO2 significantly enhances cooling performance. It increases the heat transfer coefficient by factors of 2.69, 9.97, and 6.11, respectively, while reducing the pressure drop by factors of 1.47, 4.58, and 14.52, respectively. Additionally, sCO2 decreases the maximum temperature by 4.39 K, 13.45 K, and 9.55 K compared to deionized-water, engine-oil, and ethylene-glycol, respectively. In conclusion, this research reveals that the reduction in energy consumption in sCO2-based BTMSs is driven not only by the notably low pressure drop but also by the elimination of the need for a coolant temperature recovery system.

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