Impact of wall temperature difference on heat and mass transfers in gray and non-gray gas mixtures

Abstract

This study deals with the numerical investigation of the effect of wall temperature difference ($\Delta T)$ on heat and mass transfers in a differentially heated square cavity, filled with gas mixtures (air-CO₂ or air-H₂O) at a fixed average concentration of pollutant (15% CO₂ or H₂O). The governing equations are solved by a finite-difference method and the prediction of radiative transfer in molecular gases is taken into account by the SLW model of Denison and Webb. The results are graphically displayed and discussed for two values of $\Delta T$ (5 °C and 50 °C), when the concentration and temperature gradient generate opposing motions. The results obtained with a non-gray gas are also related to those of a gray gas model, in order to investigate if this assumption is appropriate to be used instead of non-gray calculations.

Keywords:

• Convection flow
• double diffusion
• heat-mass transfer
• radiative transfer
• SLW model
• square cavity

Declaration of interest statement

The authors report there are no competing interests to declare.