Influences of Radiative Heat Transfer on the Entropy Generation Rates of Forced Convection Fluid Flow Between Two Parallel Isothermal Plates Filled with Porous Medium

Abstract

This paper deals with the entropy generation for combined convection–radiation heat transfer between two parallel isothermal plates filled with a homogeneous and uniform porous medium. The porous medium is regarded as a gray, emitting, absorbing and scattering medium. Since this medium is a radiating medium, in addition to the contributions of fluid friction (velocity gradients) and conductive heat transfer (temperature gradients) in the amount of entropy generation, the contribution of radiative heat transfer is considered. In fact, the radiative entropy generation rate is the sum of the entropy generation rates due to absorption–emission, scattering and walls effects. The calculations are done for two types of boundary conditions including hot and cold walls and in the absence and presence of the radiative heat transfer mechanism. Also, the influences of shape factor, radiation–conduction parameter and wall emissivity on the values of total entropy generation number are investigated. The results show that the radiative heat transfer mechanism has a significant effect on the magnitudes of entropy generation rates for both types of boundary conditions. Also, the magnitudes of total entropy generation numbers in the case of cold walls are higher than these magnitudes in case of hot walls.