Heat Transfer Investigation of Nano‐Encapsulated Phase Change Materials (NEPCMs) in a Thermal Energy Storage Device With Heat Source

ABSTRACT This work presents a numerical analysis of natural convection and heat transfer characteristics of nano‐encapsulated phase change materials (NEPCMs) within a square cavity filled with a porous medium. The nano‐encapsulated PCM is prepared with polyvinyl alcohol as a shell and a phase change material N‐eicosane, as a core with engine oil as a base fluid. The transformed equations, representing velocity, temperature, and entropy generation, are numerically solved by utilizing finite element method. The study examines the effects of several key parameters, including porosity , magnetic field strength , radiation , internal heat generation , nanoparticle concentration , Stefan number , fusion temperature , irreversibility parameter , and Rayleigh number . Findings show that increased porosity reduces flow resistance, leading to improved circulation and thermal diffusion. The magnetic field dampens fluid motion through the Lorentz force, weakening convection. Enhanced radiation and internal heat generation contribute to smoother and more uniform temperature fields. A higher volume fraction of NEPCMs improves thermal storage and reduces entropy generation. Additionally, increasing the Stefan number and thermal conductivity boosts heat transfer at both hot and cold walls, as reflected in the rise of the Nusselt number. Overall, the results highlight the potential of tuning material and flow properties to improve thermal performance in NEPCM‐based thermal systems.