REORDERING THE ABSORPTION-COEFFICIENT WITHIN THE WIDE-BAND FOR PREDICTING GASEOUS RADIANT EXCHANGE

The ''exact'' calculation of the radiant transfer in gaseous enclosure s has remained impractical for design; the highly complex nature of th e absorption spectrum of the gases has meant that an inordinately larg e computational effort is required to effect an exact answer. In this paper we show how the complex absorption distribution for an isotherma l gas can be replaced by a set of smooth curves. This procedure can be visualized as one of actually reordering the full complex absorption distribution within each vibration-rotation band, and then replacing i t by a smooth curve. Such a smooth curve can then be readily approxima ted by a stepwise function, and radiant exchange calculations can be c arried out at each step and then summed over all the steps to get the total exchange. This paper explains how the reordered curve can be obt ained and gives some sample plots of the reordered absorption coeffici ent curve. Fitted functions for the rearranged curves have been provid ed, and some solutions to the radiant exchange problems are given and compared to line-by-line solutions. About 50 to 200 steps in the stepw ise curve are found to be adequate in order to obtain an answer within a few percent of the exact answer.