Numerical investigation of MHD natural convection in an enclosure filled with nano-encapsulated phase change materials

Nano-encapsulated phase change materials (NEPCMs) offer enhanced thermal transport characteristics through the combined effects of sensible and latent heat. The present study performs a numerical investigation of magnetohydrodynamic natural convection in a Darcy–Brinkman–Forchheimer porous enclosure containing an NEPCM suspension under thermal radiation. The coupled mass, momentum, and energy equations are solved using a Marker-and-Cell finite-volume formulation. The effects of Rayleigh number, Hartmann number, Darcy number, porosity, radiation parameter, NEPCM volume fraction, and fusion temperature on the flow structure, temperature distribution, phase-transition region, and heat-transfer characteristics are examined. The results show that thermal radiation and buoyancy substantially modify the heat-transfer rate, whereas magnetic damping reduces convective transport. Increasing porosity and Darcy number strengthens fluid circulation and enhances the average Nusselt number. Changes in NEPCM concentration and fusion temperature modify the distribution of the phase-transition region and the resulting thermal transport. The results reveal that thermal radiation plays the most dominant role, enhancing the average Nusselt number by approximately 466% as Rd increases from 0 to 5. Increasing porosity (ε) and Darcy number (Da) improves heat transfer by nearly 44% and 22%, respectively, due to reduced flow resistance and strengthened convective circulation. In contrast, the magnetic field suppresses convection, reducing heat transfer by about 10% for Ha up to 50. For the reference conditions considered in the present ϕ -parametric study, increasing the NEPCM volume fraction from ϕ = 0.01 to ϕ = 0.05 produces an increase of approximately 9.7% in the average Nusselt number. This enhancement represents the response within the investigated parameter range and fixed reference conditions; its magnitude may vary with other governing parameters, including Ra, Ha, Da, porosity, Rd, and fusion temperature. The results provide insight into the thermo-fluid behaviour of NEPCM-filled porous systems, while transient charging/discharging characteristics require a separate time-dependent analysis.