Carbon dioxide concentration and temperature in flames by raman spectroscopy

Abstract

The interpretation and prediction of high temperature Raman spectra for CO 2 in flames requires a more detailed treatment of the upper vibrational states than is required for room-temperature spectra. A method for calculating these upper state contributions is presented and is used to evaluate the results of a series of experiments. Laser Raman CO 2 spectra have been obtained for CH 4-air, CO 2 seeded CH 4-air, and CO-air flames. The results indicate that both the high and low temperature CO 2 spectra agree with the theoretical predictions. Comparison of the CO 2 temperature to the N 2 temperature, both measured at the same position in the flames, indicates a better prediction of temperature from the N 2 spectrum than from the CO 2 spectrum. Accurate values for the CO 2 concentrations, however, can be determined from a comparison of the CO 2 spectrum with the N 2 spectrum.