In situ infrared measurements on TiO 2 flames: Gas and particle concentrations

Fourier transform infrared spectroscopy was performed on premixed flames of titanium tetraisopropoxide, methane and oxygen. A combination of emission/transmission (E/T) measurements yields gas temperature, gas concentrations, soot temperature, soot concentration and absorption features of TiO 2 particles. To validate the temperature measurements, a thermocouple is inserted into the IR path within the flame, and its temperature is compared to the surface temperature from E/T analysis which agrees quite well. The HITEMP and HITRAN databases are used to determine the gas mol fractions in the flame. Soot is observed in the emission spectra of the flame, and its concentration decreases with its increasing position above the burner. The soot temperature is always less than the gas temperature. The IR feature of TiO 2 particles is hard to observe, because it is very small relative to H 2 O and CO 2 features. Interfering features, however, were removed using either calculated spectra or by experimentally generating a reference flame using an acetone–methane flame.