Numerical simulation and theoretical analysis of thermal boundary characteristics of convection heat transfer in porous media

Abstract

The thermal boundary characteristics at the contact interface between a porous media and an impermeable wall subject to a constant heat flux on its upper surface with and without consideration of the thermal contact resistance were investigated using a particle-level numerical simulation of single phase fluid flow and convection heat transfer in porous media. The numerical simulations assumed an ideal packed bed (simple cubic structure) formed by uniform diameter particles with small contact areas and a zero- or finite-thickness wall subject to a constant heat flux at the surface which mirrors the experimental setup. The numerical simulations showed that the temperature distribution at the contact interface is non-uniform for the porous media with a zero-thickness impermeable wall, and in the porous media with a finite-thickness impermeable wall with a thermal contact resistance between the particles and the plate (such as with a non-sintered porous media) with a constant heat flux on the outer surface, while the heat flux distribution at the contact interface is quite uniform for these cases. However, in the porous media with a finite-thickness impermeable wall without a thermal contact resistance between the particles and the plate (such as with a sintered porous media) with a constant heat flux on the outer surface, the heat flux distribution at the contact interface is very non-uniform, while the temperature distribution at the contact interface is quite uniform. Numerical simulations of the thermal boundary characteristics of the convection heat transfer in the porous media were used to investigate the applicability of various boundary conditions for the energy equations with and without a thermal contact resistance between the particles and the plate wall.