Measurements and calculations of CO 2 absorption at high temperature in the 4.3 and 2.7 μm regions

Abstract

Absorption by pure CO 2 and CO 2-N 2 mixtures in the 4.3 and 2.7 μm regions has been measured with a grating spectrometer with spectral resolution of 0.75 and 2cm -1, respectively and pressures between 0.03 and 1 atm, at room temperature and around 750 K. Measurements are compared with line-by-line calculations using the spectroscopic parameters considered for the 1991 edition of the HITRAN database and those calculated by Wattson and Rothman (W-R database) with the Direct Numerical Diagonalization (DND) method. Lorentzian profiles modified by the introduction of a frequency- and temperature-dependent line shape corrective factor χ have been used. At room temperature, calculations with the two databases are consistent and in good agreement with our experiments. At 750 K, calculations with HITRAN underestimate absorption both in line 4.3 and 2.7 μm regions, whereas those with the W-R database are in good agreement with the measurements, with latter slightly underestimating the absorption in the low frequency wing of the 4.3 μm band. This may be due to inaccuracies in the χ factors and the parameters of some hot bands.