Melting of nano-phase change material inside a porous enclosure

The melting process of a nano-phase change material (or nano-PCM) in a square enclosure filled with a porous medium was investigated numerically and analytically. The dimensionless continuity, Darcy-Brinkman momentum, and energy equations were solved using the finite element method. One vertical wall of the square enclosure was heated at a constant temperature (Th), while all the other walls were insulated. The numerical results were adopted for a wide range of Rayleigh number (106⩽Ra⩽5×107), Darcy number (10-8⩽Da⩽100), and the volume fraction of nanoparticles (ϕ = 0%, 10%, and 20%). The results were expressed in terms of isothermal lines, streamlines, and Nusselt number. In addition, a scale analysis of the governing equations was performed to verify the numerical results. A validation was performed between the present study and previously reported results in the literature; a good agreement was achieved. The numerical results indicated that the melting process is improved by increasing Ra, ϕ, and Da. The scale analysis successfully predicted the behavior of the meting process of nano-PCM embedded in the porous medium.