Combined conduction and radiation heat transfer in plane-parallel packed beds with variable porosity

Abstract

The primary concern of this study deals with the prediction of thermal performance of packed beds with variable porosity. Combined conduction and radiation heat transfer in plane-parallel packed beds of spherical particles was investigated numerically. The effects of variable porosity, effective thermal conductivity, and thermal radiation were taken into account. The method for radiative transfer equation was based on the P-3-spherical harmonic approximation, while the finite-difference scheme was employed to solve the energy equation. Four different models of porosity distributions were tested. It was found that variable porosity and effective thermal conductivity effects on the mean total effective thermal conductivity and radiative heat flux distributions are important and should not be ignored. (C) 1999 Elsevier Science Ltd. All rights reserved.