Application of absorption-line blackbody distribution functions for H2O-CO2 mixtures for the spectral integration of the radiative transfer equation with the SLW model

Abstract

This study presents the generation and evaluation of absorption-line blackbody distribution functions for mixtures (ALBDF-M) of CO2 and H2O. These functions are employed in the spectral integration of the radiative transfer equation in the framework of the spectral line-based weighted-sum-of-gray-gases (SLW) model. The proposed approach avoids the need to model the mixture of gases when dealing with ALBDFs obtained for pure H2O and CO2 species, which is the methodology currently adopted in the SLW literature. The ALBDF-M can be used with any development of the SLW model to manage local variations of the thermodynamic state conditions. In the present study, both the rank (RC-) and the locally correlated (LC-) SLW methodologies are employed with the ALBDF-M for an uncouple solution of an axisymmetric field that is representative of the combustion of ethylene diluted with H2O. Comparisons with line-by-line (LBL) solutions show that using the ALBDF-M provides an improvement in the accuracy when compared to the standard methodology to combine the ALBDFs generated for CO2 and H2O individually.