Evaluation of spectral radiative properties of gases in high-pressure combustion

Radiative heat transfer affects local flame temperatures, and thus pollutant formation in high-pressure diffusion flames but the radiation properties of major gas species at pressures and temperatures relevant for combustion engines are not well known. In order to facilitate radiative transfer calculations in these types of flames, new and already published CO₂ and H₂O absorption spectra at high pressure and temperatures have been used to validate their modelled spectra based on the HITEMP 2010 database. Corrections for non-Lorentzian behavior of collisional-broadened lines have been evaluated, where an adjustable pseudo-Lorentzian line profile has been correlated for CO₂ − N₂ mixtures over a wide range of pressure, temperature and concentration. A fixed pseudo-Lorentzian line profile was found to give similar performance to previous empirical line corrections when comparing to available experimental H₂O data over a relatively wide pressure and temperature range. The work has led to the release of an in-house MATLAB code, named RadISpeC freely available for download. The code efficiently produces spectra for radiation calculations for both soot and gas at high pressures and temperature.