Pyc. Lee et al., REORDERING THE ABSORPTION-COEFFICIENT WITHIN THE WIDE-BAND FOR PREDICTING GASEOUS RADIANT EXCHANGE, Journal of heat transfer, 118(2), 1996, pp. 394-400
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.