A full spectrum k-distribution based weighted-sum-of-gray-gases model for oxy-fuel combustion

Oxy-fuel combustion has become one of the most promising technologies for carbon capture and storage (CCS) in coal-fired plants. Radiative properties of combustion gases in oxy-fuel combustion are significantly different from those found in air-fired due to the change of the gas composition. A few modified weighted-sum-of-gray-gases (WSGG) models had been proposed to consider the wide H2O to CO2 ratio for oxy-fuel combustion in recent years. As most of the models are validated using simple homogenous benchmark, the applicability of such models to non-homogeneous media is questionable. In this paper, based on the up-to-date HITEMP 2010 database, we obtain new parameters of WSGG model for oxy-fuel combustion by combining the features of full-spectrum k-distribution (FSK) model with WSGG model, in which the weighting factors and absorption coefficients are directly obtained from the k-distribution, and the polynomial expression of absorption coefficient is improved. The new parameters of WSGG model are extensively validated by comparing the radiative source terms and radiative heat fluxes, predicted with the line-by-line (LBL) model integration of HITEMP 2010 database at a one-dimensional slab system. The predictions by different parameters of WSGG model from the literature are also included in comparison. The investigative cases include the non-isothermal and/or non-homogeneous gas mixture. The maximum relative error of heat fluxes is 11.2% for the new parameters, 33.5% for Yin model (Yin et al., 2010) and 23.0% for Johansson model (Johansson et al., 2011) in non-isothermal non-homogeneous gas mixture. The results show the new parameters can significantly improve the prediction accuracy in non-isothermal non-homogeneous CO2/H2O mixture.