The technique of flame temperature measurement plays an important role in combustion diagnostics. Usually, in a high-temperature energy transport process, the greatest portion of flame radiation heat loss comes from combustion products emitting in the infrared (i.r.) region. In this paper, a special detector is used to measure the i.r. intensity of a propane flame. By comparing these results with an isothermal blackbody source, the flame temperature can be obtained. The results from the i.r. measurements show good agreement with the temperature measured by thermocouples. This confirms that flame temperature measurement by means of an i.r. technique is feasible. In flame emissivity, the i.r. system uses a 4.3 μm band filter for CO2 species; then an iteration method and a wide-band model theory are adopted to calculate spectral emissivity. Optically thin and optically thick theories are also adopted to calculate the soot emissivity in order to obtain the theoretical equivalent cross-section emissivity for a propane burner flame. Furthermore, an empirical correlation to predict the cross-section emissivity of a propane premixed lean flame can be obtained through statistic analysis.
Journal of Quantitative Spectroscopy and Radiative Transfer, vol. 56, issue 1, pp. 133-144