Gray and non-gray simulations of the combined conduction and radiation heat transfer in a complex enclosure utilizing FSK method considering the scattering influences

Abstract

This research simulates the conduction-radiation problem in a complex enclosure for the gray/ non-gray assumptions with the presence of scattering influences to improve energy efficiency of thermal systems. The enclosure bottom wall includes an inclined recess with two diagonal walls. To convert these diagonal surfaces to the regular rectangular surfaces in Cartesian coordinates, the Blocked-off method is used. The air containing 10% CO2 and 20% H2O is regarded as participating medium in the enclosure. The absorption coefficient of this mixture is obtained across the spectrum using the information of HITRAN2008 database. Simulating the non-gray medium is done by employing the full-spectrum k-distribution (FSK) approach, whilst the gray medium simulation is performed utilizing the Planck mean absorption coefficient. The finite volume and discrete ordinates methods are respectively applied to calculate the energy and radiation transport equations. Impacts of surface emissivity on conductive, radiative and total heat fluxes are examined in details.