Enhancement of thermal and heat transfer capabilities of phase change materials with addition of nanoparticles is reported. The mixed nanofluid of phase change material and nanoparticles presents a high thermal conductivity and low heat capacity and latent heat, in comparison with the base fluid. In order to present the thermophysical effects of nanoparticles, a solidification of nanofluid in a rectangular enclosure with natural convection induced by different wall temperatures is considered. The results show that the balance between the solidification acceleration by nanoparticles and slowing-down by phase change material gives rise to control the medium temperature. It indicates that this kind of mixture has great potential in various applications which requires temperature regulation. Also, the Brownian motion of nanoparticles enhances the convective heat transfer much more than the conductive transfer.

The aim of this paper is the numerical investigation of local thermal non-equilibrium effects in the boundary-layer forced convection of a third grade fluid flowing in a porous medium confined by two parallel permeable stretching isothermal plates. The horizontal velocity of stretching walls is proportional to the longitudinal distance from origin while its vertical suction component is uniform. The porous medium obey the Brinkman extended Darcy momentum equation. The boundary-layer non-linear PDE are transformed by similarity solution to a system of ODE. The numerical investigation make known that a flow reversal come about the symmetry line of the channel attributable to the stretching plate boundary which diminished in highly Darcy numbers. The fluid-flow field and temperature distribution of the solid and fluid phases are studied based on the conductivity ratio, Darcy number, Prandtl number, Reynolds number, and third order fluid parameters.