Optimization of thermal energy storage in phase change Material/Nano additive heat exchangers utilizing elliptical and circular tubes with and without fins

This study numerically investigates the enhancement of thermal energy storage systems using phase change materials (PCMs) combined with nano additives and finned tubes. The analysis compares elliptical and circular tubes with configurations of two or four fins to improve heat transfer efficiency. Finned elliptical tubes demonstrate a reduction in PCM melting time by up to 19 % at 50 °C, achieving faster melting compared to unfinned designs. Circular tubes with fins also exhibit a 12.6 % reduction in melting time, showing slightly higher thermal performance than elliptical tubes in certain conditions. The study considers different nano additives—graphene nanoplatelets (GnP), copper (Cu), copper oxide (CuO), and aluminum oxide (Al₂O₃)—to evaluate their impact on PCM heat transfer rates. Among these, GnP achieves the most effective thermal enhancement. The findings indicate that fin configuration, tube geometry, and nano additives significantly affect PCM melting and heat transfer dynamics. This research optimizes the design of PCM-based heat exchangers, contributing to more efficient and sustainable thermal energy storage solutions for various applications.