Account for ratios of H2O to CO2 in the calculation of thermal radiation of gases with the weighted-sum-of-grey-gases model

The standard formulation of the weighted-sum-of-grey-gases (WSGG) model uses parameters that are fitted to a range of temperatures but only for specific ratios of H2O to CO2. As such, the model is limited to specific fuels with the proper composition of hydrogen and carbon unless several setups of parameters are used. Here, the WSGG model is modified to account for various ratios of H2O to CO2. To test the model, predictions of the radiative source term and wall fluxes in a gaseous domain between two infinite plates are compared with predictions by a statistical narrow-band model. Included in the comparison are also two grey approximations, which is a common approach to account for gaseous radiation in comprehensive combustion models. Results show that the modified WSGG model significantly improves the estimation of the radiative source term compared to the grey models, although the accuracy of the wall fluxes is of the same magnitude