Mixed convection boundary layer flow and heat transfer over a vertical plate embedded in a porous medium filled with a suspension of nano-encapsulated phase change materials

The flow and thermal behavior of nano-encapsulated phase change materials (NEPCMs) dispersed in a liquid is investigated over a vertical flat plate. The NEPCM particles are consist of an encapsulation shell and a core made of phase change materials (PCMs). When the temperature of the liquid around the NEPCM particle is higher than the fusion temperature of the PCM core, the PCM core absorbs a notable amount of heat (the latent heat of the phase change) from the host fluid and melts. The vertical plate is embedded in a porous medium, and the porous medium is saturated with the suspension of NEPCM. There is a uniform flow over the plate, which can aid or oppose the natural convection flow over the plate. The partial differential governing equations for the flow and heat transfer of NEPCM suspension are introduced and transformed into a high order boundary value ordinary differential equation. The finite difference method with a colocation technique as the grid adaptation and automatic error control is utilized to integrate the governing equations. Validations are performed by comparing the results with the literature. It is found that there are two solution branches in the case of high opposing flows. The results indicate that the presence of NEPCM particles enhances the heat transfer over the plate. The decrease in the fusion temperature of NEPCM cores enhances the heat transfer. (C) 2019 Published by Elsevier B.V.