Spectral and total emissivity of water vapor and carbon dioxide

Artikel i vetenskaplig tidskrift, 1972

Data on the infrared radiation characteristics of carbon dioxide and water vapor in the form of absorption coefficients and line spacings averaged over narrow spectral intervals have been compiled from various sources. These data are to be used in heat transfer calculations from hot gases. In order to investigate the accuracy of the data, the simplest case possible is chosen: a comparison with the total emissivity charts of water vapor and carbon dioxide. It appears however that the charts are not entirely reliable as standards for comparison: it seems probable that Hottel's chart for water vapor gives too low values at temperatures above 900°C and that the partial pressure correction is temperature dependent. With the exception of some regions where judgment is difficult, the calculations using spectral data seem to represent total emissivities with a maximum error which is estimated to around 10%. Sources of error in the spectral data and in Hottel's total emissivity charts are discussed. Total emissivity charts, pressure and overlap corrections based on calculations with spectral data are presented.