Heat transfer enhancements in heat exchangers fitted with porous media Part I: constant wall temperature

This work investigates heat transfer enhancement for a flow in a pipe or a channel fully or partially filled with porous medium. The porous layer inserted at the core of the conduit. Forced, laminar flow is assumed and the effects of porous layer thickness on the rate of heat transfer and pressure drop were investigated. The Darcy number (permeability) is varied in the range of 10(-6) to 10.0. Developing and fully developed flow conditions are considered in the analysis. It is found that the plug flow assumption is not valid for Da > 10(-3). The effect of varying the inertia term (Forchheimer term) is also investigated and it is found that the inertia term is not that important for Da < 10(-4) for the range of the parameters investigated. Partially filling the conduit with porous medium has two advantages: it enhances the rate of heat transfer, and the pressure drop is much less than that for a conduit fully filled with a porous medium. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.