A fictitious-gas-based absorption distribution function global model for radiative transfer in hot gases

The absorption distribution function model with fictitious gases (ADFFG), a new global model of gas radiative properties, is presented and implemented for CO2 and H2O radiation at atmospheric pressure and in the temperature range (300-2000 K). The model is based on the joint distribution function of the absorption coefficients of two fictitious gases corresponding to hot and cold lines of a given species. Model parameters are deduced from line-by-line (LBL) calculations founded on the EM2C spectroscopic databases. The accuracy of ADFFG is studied, for nonisothermal and nonhomogeneous columns representative of engineering applications, by comparisons with reference LBL calculations and results of the CK and CKFG narrow-band models. It is shown that the subdivision into two fictitious gases significantly enhances the accuracy of ADF (the same model without subdivision), in particular when gaseous absorption is significant, at the cost of larger computing times. Like all global models, ADFFG is, however, limited to applications where walls and particles are gray. (C) 1999 Elsevier Science Ltd. All rights reserved.