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 r ange (300-2000 K). The model is based on the joint distribution function of the absorption coefficients of two fictitious gases corresponding to hot a nd cold lines of a given species. Model parameters are deduced from line-by -line (LBL) calculations founded on the EM2C spectroscopic databases. The a ccuracy of ADFFG is studied, for nonisothermal and nonhomogeneous columns r epresentative of engineering applications, by comparisons with reference LB L calculations and results of the CK and CKFG narrow-band models. It is sho wn that the subdivision into two fictitious gases significantly enhances th e accuracy of ADF (the same model without subdivision), in particular when gaseous absorption is significant, at the cost of larger computing times. L ike all global models, ADFFG is, however, limited to applications where wal ls and particles are gray. (C) 1999 Elsevier Science Ltd. All rights reserv ed.