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 CO$_2$/N$_2$ mixtures at temperatures of approximately 773K and 1273K 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 CO$_2$ 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. (Combust. Flame 162 (2015) 597–612) and the Price line-shape function modified with one of the two $\xi$ corrections of Westlye et al. (J. Quant. Spectrosc. Radiat. Transfer 302 (2023) 108555; J.Quant. ... mehrSpectrosc. Radiat. Transfer 280 (2022) 108089) 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 $\xi$ 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 $\xi$ correction of Westlye et al. only proved superior for gas mixtures with 20% CO$_2$ and 80% N$_2$ (in mole fractions).