Wide band cumulative absorption coefficient distribution model for overlapping absorption in H2O and CO2 mixtures

An accurate wide band cumulative absorption coefficient distribution, g(k), model for thermal radiative transfer in gaseous media containing H2O and CO2 is presented. Assuming that the convoluted g(k) function for gas mixture retains the same functional form as the individual gases, the model treats overlapping bands as a “single”, complex band with scaled parameters. Corresponding scaling algorithms are proposed for specific overlapping regions. Predictions of the mixture g(k) function and the band absorptance are in good agreement with the line-by-line calculation over a wide range of temperatures from 500 to 2500 K, and pressures up to 10.0 atm. The g(k) model is generally more accurate than the exponential wide band model, and provides comparable accuracy to the statistical narrow-band model in predicting the total emissivity along an isothermal and homogeneous gas column under typical combustion conditions. In addition, this approach significantly enhances the computational efficiency.