Thermal radiation at high-temperature and high-pressure conditions: Validation of HITEMP-2010 for carbon dioxide

Line-by-line models based on spectroscopic databases are powerful tools for the generation of accurate gas absorption spectra but still require validation for high-temperature and high-pressure conditions. Therefore, this study carried out spectral transmissivity measurements of CO2/N2 mixtures at temperatures of approximately 773 K and 1273 K and pressures between 1 bar and 60 bar. The measurement data was obtained in a spectral range from 1900 cm−1 to 6600 cm−1 at a spectral resolution of 1 cm−1 and was compared with line-by-line predictions. The comparisons show that the absorption spectra of CO2 can be predicted for high-temperature and high-pressure conditions with good accuracy if the line-by-line calculations are performed using modified line profiles and the HITEMP-2010 database. In comparison with standard line-shape functions, both the Voigt line-shape function combined with the cut-off criterion of Alberti et al. (2015) and the Price line-shape function modified with one of the two ξ corrections of Westlye et al. (2023, 2022) provided significantly superior predictions. However, deficiencies of the cut-off criterion of Alberti et al. become clear in the transmissivity predictions of the right wings of the 4.3 µm band and the 2.7 µm band. The Price line-shape function combined with the first ξ correction of Westlye et al. was able to overcome these erroneous predictions of the wings, while the Price line-shape function modified with the second ξ correction of Westlye et al. only proved superior for gas mixtures with 20% CO2 and 80% N2 (in mole fractions).