Full-spectrum k-distribution weighted sum of gray gases model for air and oxyfuel combustion of hydrogen-hydrocarbon blends at atmospheric pressure

In the context of decarbonization of heating processes, alternative fuels as hydrogen, ammonia, or biogas are explored to substitute conventional fuels as natural gas. The altered flue gas compositions from such flames demand flexible modeling of radiative properties of the participating gases H 2 O and CO 2 . Various Weighted Sum of Gray Gases (WSGG) model formulations and coefficients have been proposed in the literature, but few cover all conditions that result from the combustion of any blend of the aforementioned fuels. In this work, two sets of coefficients for a WSGG model with 5 gray gases are calibrated for air and oxyfuel combustion conditions at atmospheric pressure, to improve on the accuracy and flexibility of existing models. Weights and absorption coefficients are derived from k -distributions based on line-by-line integrations using the HITEMP 2010 spectroscopic database. Base functions are fitted to continuously recover the weights and absorption coefficients within the range of calibration. The new model covers H 2 O to CO 2 molar ratios of 1 ≤ M r ≤ ∞ , and temperatures in the range of 300 K ≤ T ≤ 2700 K for air combustion, and 300 K ≤ T ≤ 3000 K for oxyfuel combustion. The models are assessed by predictions of total emissivity as well as radiative heat flux and source term in a 1D slab. Benchmark solutions are obtained from line-by-line integrations covering the compositions of the calibration database. The new model shows significantly improved predictions in comparison to recent WSGG models. • WSGG coefficients are fitted for a range of CO 2 to H 2 O molar ratios of 1 ≤ M r ≤ ∞ . • Modeling coefficients are derived from full-spectrum k -distributions. • Coefficient sets are calibrated for air and for oxyfuel combustion flue gas. • Increased accuracy in prediction of emissivity and radiative heat flux in a 1D-slab.