Numerical investigation of enhanced battery thermal management system performance using radial fin-intensified phase change material: Focus on latent heat contribution

Abstract

Electric vehicles (EVs), which are critical in controlling carbon emissions and protecting ecological harmony and human well-being, are reinforcing their key role in the transportation sector. However, EV batteries can ensure high performance, prolonged service life, and safe driving only with proper and effective battery thermal management systems (BTMSs). The focus and major contribution of this study to literature is to reveal the role of phase change material's (PCM's) latent heat to the thermal performance of batteries, differentiating the latent heat from the overall thermal energy storage capacity which includes both sensible and latent heat. For that purpose, the phase stable material approach, which is a material with the identical thermophysical properties as PCM but does not undergo phase transformation, was applied. In the study, aluminum radial fin intensified approaches are utilized to enhance the thermal performance of PCM-based BTMS. Additionally to the reference model adding only PCM, 3 different simulation scenarios were analyzed: i) PCM + 1 fin (Design-I), ii) PCM + 3 fins (Design-II), iii) PCM + 5 fins (Design-III). The study was conducted under 5C discharge conditions by integrating 3 different PCMs (RT31, RT38, and RT42) and the impacts of fin distribution, fin dimensions, and housing diameters on thermal behavior of PCM and maximum temperature of battery were numerically studied. The results revealed that the fins enhanced the low thermal conductivity of the PCM by increasing the heat transfer area and can be further improved depending on the intensification of the fins. The refinement of the fin distribution accelerated heat transfer. Compared to the reference case, the temperature decrease was approximately 23.22 %, 12.64 %, and 11.12 % for RT31, RT38, and RT42 in Design-III, respectively. The increase in fin length led to a temperature reduction of up to 2.23 °C, demonstrating greater effectiveness compared to the increase in fin thickness. Reducing the inner diameter of the housing from 34 mm to 26 mm slightly increased the temperature values, but the influence on the liquid fraction was considerable. At the end of the discharge process, the liquid fraction reached from 36 % to 89 %, 28 % to 76 % and 19 % to 65 % for RT31, RT38, and RT42, respectively. Contribution of latent heat in reducing the temperature was 21.94 % in the reference case, 23.51 % in Design-I, 25.4 % in Design-II, and 33.62 % in Design-III.