Heat transfer enhancement using porous inserts

This paper presents the results of an analysis of heat transfer in rectangular channels containing a porous insert. The objective is to investigate if it is possible to use porous inserts to enhance heat transfer. Momentum transfer in the porous region is modeled with the Brinkman-Extended Darcy model. For the fluid region, momentum transfer is modeled with the Navier-Stokes equation. These equations are solved analytically and the resulting solutions for the velocities are combined with the energy equations describing heat transfer in the fluid and porous regions. A variable grid-size implicit finite-difference method is used to solve the energy equations. Heat transfer between the channel walls and the fluid is determined as a function of Darcy number, ratio of the fluid and porous medium thermal conductivities, and the porous insert thickness. It is shown that heat transfer could be enhanced by placing a porous insert in the channel. Moreover, for some conditions heat transfer is maximized by using a porous insert thinner than the channel height while a porous insert that completely fills the channel is needed for other conditions.