Effects of porous medium filling on thermally developing forced convection in a parallel plate channel

This study obtains the semi-analytical solutions and explores the thermal characteristics of a thermally developing flow in a parallel plate channel, partially filled with a porous medium at the core, while considering local thermal non-equilibrium conditions, and viscous dissipation for the first time. The developing temperature field, for a porous medium filling of volume fraction fixed at 0.9, indicates an increasing difference in temperature between the solid and fluid phases with the axial distance. Besides, heat flux bifurcation starts in the entrance region as more heat diffuses to the solid at the interface, more markedly with a decreasing Darcy number, Da. When the thermal transport is dominated by interstitial heat transfer between solid and fluid in the porous medium, the thermal entrant length is the shortest. An increasing amount of porous medium filling with such quality and an increasing Da tend to shorten the thermal entry length. Nonetheless, as a lower Da porous media convects more heat away from the interface, it expedites the thermal development in cases where interstitial heat transfer in porous medium is poor. With an increasing porous medium fraction, the impact of viscous dissipation on heat transfer magnifies at the entrance region, thereby reducing the effectiveness of porous medium insert.