Optimizing thermal performance in PCM packed beds: a comparative study of spherical and cylindrical capsules

Abstract This study delves into the thermal performance and exergy efficiency of PCMs within packed bed systems, employing capsules of varied shapes—spherical and cylindrical. Utilizing COMSOL Multiphysics 6.0 for simulation, this research constructs a three-dimensional model to numerically analyse the discharging processes of these packed beds. A comparative analysis of three distinct packed bed systems under identical operational conditions was conducted, focusing on liquid phase changes, temperature profiles, and exergy parameters. The study examines individual configurations of spherical capsules, cylindrical capsules, and a hybrid combination of both, assessing their heat transfer capabilities and exergy storage performance. The findings reveal that the hybrid configuration of spherical and cylindrical capsules (Case 2) provides an optimal balance of rapid heat transfer and efficient exergy management. Furthermore, during the discharging phase, this combined configuration sustained higher exergy efficiencies, underscoring its potential for more effective and prolonged heat transfer applications.