Pressure-dependent weighted-sum-of-gray-gases models for heterogeneous CO2-H2O mixtures at sub- and super-atmospheric pressure

The effect of total pressure of gas mixture is included in the development of new coefficients for the weighted-sum-of-gray-gases model (WSGG). The WSGG formulation previously reported by Bordbar et al. (combustion and Flame 2014, V. 161, pp. 2435-2445), which accounts for variations of molar fraction ratio of H2O to CO2, was employed here to obtain a new total pressure-dependent WSGG model. Hence, the new model includes both the effect of total pressure and variation of molar fraction ratio. High-resolution absorption spectra of gases produced by line-by-line (LBL) calculations using the HITEMP2010 spectral database are used to produce the total emissivity databases needed for the WSGG model development and also to produce the benchmark solution of one-dimensional slab problems used for validation of the new model. The performance of the new WSGG model is studied through several test cases representing various conditions of total pressure, inhomogeneity of temperature, concentration of gas species and molar fraction ratios. In all cases, the new model exhibits a good agreement with the LBL solutions. The new WSGG coefficients allow the model to efficiently solve the spectral thermal radiation in both sub- and super-atmospheric combustion systems. (C) 2021 The Author(s). Published by Elsevier Ltd.