A technique for extrapolating absorption coefficient measurements to high temperatures

An extrapolation technique that provides semi-quantitative estimates for the infrared absorption coefficients of gaseous fuels at temperatures beyond those for which measurements are generally practical (>700 K) is presented. The new method is based on a simplified expression for molecular line intensities consisting of three fitting parameters and two variables (temperature and frequency). The accuracy of the extrapolations was tested first by comparing predictions of absorption coefficients for CO, CO2, and H2O vapor to the corresponding values obtained directly from the HITEMP molecular database. Finally, to establish the practical utility of the method, the spectrum of propane at 1000 K obtained from the extrapolation technique was compared to actual experimental measurements. 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.