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Abstract
Particle and gas temperature measurements by both a multiple wavelength visible pyrometer and IR emission-absorption method are presented. Particle two-color temperatures are found to be dependent on the selected wavelengths because of the presence of mineral matter emission lines (Na, Li, K, Rb). Visible and IR particle temperatures do not agree. An underestimation of 200–400 K of the IR temperature due to scattering was observed. The use of a scattering correction coefficient calculated from the Mie theory for transmittance data resulted in a reasonable adjustment of this temperature.
From spectral measurements in the range of 0·4-5 μm, contribution to heat transfer was found to be limited to large particles, the 4·3 μm CO2 band, and to soot when these are present in the bulk gas. Curiously the 2·7 μm water vapor band is practically nonexistent.
Measurements were performed in coal-argon-air flames generated in cylindrical electric furnace at different oxygen concentrations for size graded (93 μm mean diameter( samples of a high V-M bituminous coal.