Spectral radiative entropy generation in a non-gray planar participating medium including H 2 O and CO 2

Abstract

Spectral radiative entropy generation through a non-gray absorbing and emitting planar medium is stud- ied. Spectral radiative properties are calculated using the correlated-k (CK) non-gray model with updated parameters based on the HITEMP2010 high-resolution database. The angular and spatial discretization of the radiative transfer equation and radiative entropy generation equation are performed using the dis- crete ordinates method and the finite volume method, respectively. First, results obtained using the CK model, are compared with the results of the gray model. The calculations reveal that there is a significant difference between results obtained by the gray model and the non-gray model, and the gray assumption generates a remarkable error in the calculations of radiative entropy generation. Then, for comprehen- sive analysis, five cases have been considered including two homogeneous and isothermal cases, two non-homogeneous and non-isothermal cases filled with H 2 O or CO 2 and one homogeneous and non- isothermal case with a mixture of H 2 O and CO 2 . Spectral, local and total radiative entropy generation are calculated for each case and the effect of temperature of the medium, the concentration of participating gas and wall emissivity on radiative entropy generation is attentively investigated. Results show that the radiative entropy generation in the system increases as three aforementioned parameters increase but the effect of gas temperature variations is more than others. Further, the sensitivity of radiative entropy generation due to wall radiation to wall emissivity is decreased when εw rises.