ROLE OF EMISSIVITIES IN RADIATIVE TRANSPORT CALCULATIONS

The radiation flux in gases with spectrally similar absorption coefficient, under the condition of thermal emission, can be expressed in terms of the Planck function and the emissivity function. With the use of the relations between the emissivity and the modified emissivity, the emissivity and the integrated band emissivity, and the modified emissivity and the Rosseland mean absorption coefficient, the general flux expression reduces to the various approximations in their respective limits. For these absorbing gases, therefore, the emissivity assumes a fundamental role in radiative transport calculations. © 1968.