Validity of band-model calculations for CO₂ and H₂O applied to radiative properties and conductive-radiative transfer

A previously presented line-by-line (LBL) calculation is used to test the validity of various approximate models. Narrow-band model parameters are generated from the lines used by the LBL approach in the 150-8000 cm^-1 and 300-1500 K ranges. The accuracy of narrow-band models and of approximations for nonuniform paths applied to transmissivities and intensities of columns is studied. Random-statistical models give good results for the transmissivities but inaccurate results for the emitted intensities. Applications to combined conductive-radiative transfer in one-dimensional media are then presented. The temperature and flux distributions predicted by wide-band models are accurate when radiative transfer is preponderant; narrow-band models must be used in the case of optically thin media (e.g. in boundary layers).