Semi-analytical investigation of fin configuration effects on PCM solidification in cylindrical thermal energy storage systems

Thermal energy storage systems (TES) employing phase change materials (PCMs) are often constrained by the inherently low thermal conductivity of PCMs, resulting in slow heat transfer and prolonged charging and discharging processes. This study investigates the influence of fin configuration and fin number on the solidification behavior of PCMs in TES systems using a semi-analytical model based on Green’s function and the Megerlin method. The proposed framework predicts the evolution of the solidification front under different thermal boundary conditions while providing a computationally efficient alternative to conventional computational fluid dynamics (CFD) simulations. The thermal performances of radial and longitudinal fin configurations are systematically compared to identify the most effective design for accelerating solidification. The results demonstrate that fin geometry has a greater influence on heat transfer enhancement than simply increasing the fin surface area. Among the investigated configurations, the two-radial-fin arrangement reduces the total solidification time by 21.38% compared with the unfinned tank and achieves an additional 12.37% reduction relative to the longitudinal-fin configuration. Moreover, the predicted solidification contours show that radial fins promote more effective heat extraction and suppress the formation of large unsolidified liquid regions. The proposed semi-analytical framework provides an accurate and computationally efficient tool for analyzing PCM solidification and offers practical design guidelines for optimizing fin configurations in high-performance LHTES systems.