Comparison of models for predicting band emissivity of carbon dioxide and water vapour at high temperatures

A comparison of different models for predicting band emissivity of CO2 and H2O at temperatures up to 1550 K is presented. The calculations do not contain line-by-line databases only; a narrow-band as well as a wide-band model are also included. The main objective of this work is in comparing the spectral transmissivity and band emissivity values obtained from line-by-line calculations using the most recent HITEMP-2010 as well as CDSD-1000 spectral database with measured data. Differences between the previous HITEMP-2004 and the HITEMP-2010 spectral databases are depicted. The measurements are also compared with a narrow-band model as well as a wide-band model because both have frequently been used in heat transfer calculations. It is demonstrated that line-by-line calculations show high accuracy when computing CO2 transmissivities but inaccuracies still remain in case of H2O at temperatures above 1000 K. The narrow-band model as well as the wide-band model show larger discrepancies if compared to the line-by-line predictions.