Enhancing heat transfer in parallel-plate channels by using porous inserts

In the present work, transient forced convection in the developing region o f parallel-plate ducts is numerically investigated. A high-thermal conducti vity porous substrate is attached to the inner wall of one plate in order t o enhance the heat transfer characteristics of the flow under consideration . The Darcy-Brinkman-Forchheimer model is used to model the now inside the porous domain. The present study reports the effect of several operating pa rameters on the flow hydrodynamics and thermal characteristics. Mainly, the current study demonstrates the effects of porous layer thickness, Darcy nu mber, thermal conductivity ratio, and microscopic inertial coefficient on t he thermal performance of the present Row. It is found that the highest Nus selt Number is achieved at fully porous duct. Results show that for Darcy n umber less than 10(-4), the effect of microscopic inertial coefficient can be eliminated while for large microscopic inertial coefficient, higher than 10(3), the effect of Darcy number is observed to be insignificant. Heat tr ansfer can be enhanced by: (1) using high thermal conductivity inserts, (2) decreasing Darcy number, and (3) increasing microscopic inertial coefficie nt. Also, the study shows that in the developing region, Darcy number and m icroscopic inertial coefficient have higher effect on the thermal and hydro dynamic behavior of the flow than that in the fully developed region. (C) 2 001 Elsevier Science Ltd. All rights reserved.