Infrared Radiative Heat Transfer in Nongray Gases

摘要

The object of the investigation was to study various approximate methods of analyzing infrared radiative heat transfer in nongray nonisothermal gases. For this purpose, a very simple physical system was chosen, and this consists of a gas bounded by two infinte parallel black plates having the same uniform temperature. There is a uniform heat source (or sink) within the gas. Furthermore, attention was restricted to gases having a single fundamental vibration-rotation band, such that the results are quantitatively applicable only to diatomic gases. The qualitative conclusions, however, apply to any gas which radiates in the infrared. It is found that for intermediate optical thicknesses, the line structure of the vibration-rotation band can have a significant effect upon the temperature distribution within the gas. Predictions based on the gray gas assumption are shown to be greatly in error. It is further illustrated that one cannot apply the optically thick limit to an entire vibration-rotation band, since there will always be an optically non-thick region in the band wings, and such regions will contribute significantly to the radiative transfer process. (Author)