Infrared Radiative Energy Transfer in Gases

Abstract

This chapter illustrates the incorporation of spectroscopic information into the radiative transfer equations and presents a reasonable means of treating radiative energy transfer within gases. Specific restriction is made to infrared gaseous radiation that results from molecular transitions involving both vibrational and rotational energies, and emphasis is placed upon the application of the molecular band models to radiative transfer analyses. The chapter also reviews the infrared band spectra, introduces simple band models, and discusses the formulation of total band absorptance information with the aid of these models. The basic equations describing the radiative transfer within an infrared absorbing–emitting gas are formulated and these allow for the radiatively induced departures from local thermodynamic equilibrium. The chapter also presents some illustrative radiative transfer analyses, with emphasis upon physical interpretations and the relative importance of thermal radiation versus molecular conduction as energy transport mechanisms.