Criterion for Local Thermal Equilibrium in Forced Convection Flow Through Porous Media

In this paper a general criterion for local thermal equilibrium is presented in terms of parameters including the effective fluid Prandtl number, the particle Reynolds number, the effective solid-to-fluid thermal conductivity ratio, the Darcy number, the Nusselt number and porosity. In order to check the validity of the proposed criterion for local thermal equilibrium, the forced convection phenomena in the porous medium between two parallel plates subjected to constant temperature are studied by a numerical method based on the Brinkman-Forchheimer extended Darcy model. The proportion of temperature difference between solid and fluid phases in a representative elementary volume to the temperature rise of fluid is studied by comparing the effects of relevant parameters in this new criterion. In addition, the proposed criterion is consistent with the existing experimental and numerical results for convection heat transfer in porous medium.