CROSS-FLOW HEAT EXCHANGER EMBEDDED WITHIN A POROUS MEDIUM

The present work examines numerically the cross-flow and heat transfer from a bundle of staggered cylinders embedded in a porous medium. The effects of Reynolds number within the laminar flow regime, permeability, and thermal conductivity of the porous material on the fluid flow and heat transfer from the cylinders in the cross-flow are examined. Also, the results are compared with heat transfer from a cylinder embedded in a porous medium. Prandtl number is fixed to 1.0 for gases. It is found that the porous medium may enhance the rate of heat transfer if the permeability of the porous material is high, that is, the Darcy number is greater than 10(-3). Also, increasing the thermal conductivity of the porous material has a positive effect on enhancing the rate of heat transfer from the single column of cylinders or from the cylinders in the first column of a multicolumn heat exchanger. However, the porous medium may have a negative effect on the rate of heat transfer from downstream cylinders, where the temperature gradient decreases because of the enhanced rate of heat transfer from the upstream cylinders.