Thermal Non-Equilibrium Forced Convective Flow in an Annulus Filled with a Porous Medium

In light of a local thermal non-equilibrium model, fully developed forced convection in an annulus filled with a porous medium is treated to elucidate its exact temperature solutions for both fluid and solid phases. In this study, the plug-flow approximation is assumed since Darcian velocity over the cross-section is uniform except in a small region very close to the walls. The inner wall is heated under the constant heat flux condition while the outer wall is subject to the adiabatic boundary condition. The exact solutions based on the present local thermal non-equilibrium model clearly show that the local thermal equilibrium assumption may fail for the case of metal foam and air combination. The approximate solution for the Nusselt number, which is in accord with the corresponding exact solution, has also been presented for possible engineering applications.