Radiative heat transfer calculation of oxy-fuel flames using the multi-group full-spectrum K-distribution method

•The accuracy of FSCK and MGFSK in oxy-fuel flames is investigated.•MGFSK includes 3 correlated-K solution schemes and 2 grouping strategies.•MGFSK is more accurate than corresponding FSCK for both dry and wet oxy-fuel flames.•MGFSK reduces the dependence of FSCK on the reference (or Planck) temperature.•MGFSK reduces the dependence of FSCK on the flame scale. Oxy-fuel combustion has drawn much attention as a promising CO2 capture and storage/sequestration technology. Radiative heat transfer of oxy-fuel flames is more important than that of conventional flames owing to higher concentrations of radiating gases. The Full-Spectrum Correlated K-distribution (FSCK) methods with original correlated-K scheme (Modest and Zhang, 2002), the improved one (Cai and Modest, 2014), and the rank correlated one (Solovjov and Webb, 2018) provide obvious errors in the low-temperature regions of dry and wet oxy-fuel flames. To improve the accuracy of FSCK, the accuracy of the Multi-Group FSK (MGFSK) method with the three correlated-K schemes and two grouping strategies based on the scaling function and intervals of comonotonicity are investigated in two 1D, a 2D and a 3D oxy-fuel flames. The results show that MGFSK with different correlated-K schemes and grouping strategies demonstrate better accuracies than corresponding FSCK for both dry and wet oxy-fuel flames. MGFSK reduce the dependence of FSCK on the reference (or Planck) temperature and flame scale. The volume-averaged mole fractions of the maximum and minimum temperatures are recommend as the high- and low-temperature grouping states respectively. Dividing the spectral absorption coefficients into 2 to 4 groups is a good compromise between accuracy and efficiency.