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Measurement on the Surface Temperature of Dispersed Chars in a Flat-Flame Burner Using Modified RGB Pyrometry

Xu, Yang, Li, Shuiqing, Yuan, Ye, Yao, Qiang
Energy & Fuels 2017 v.31 no.3 pp. 2228-2235
burning, cameras, models, prediction, spectrometers, surface temperature
A new spectral-emittance method to modify RGB pyrometry is developed for the surface temperature measurements of dispersed chars in a Hencken flat-flame burner. Nikon D300s, with calibrated spectral response, was used as the detector for the measurement. First, we calculated an original lookup table for ratio–temperature of the camera on the basis of the blackbody assumption. Second, 420/440 two-color pyrometry using an intensified charge-coupled device (ICCD) combined with two adjacent bandpass filters centered at 420 and 440 nm was adopted here for a verified comparison to RGB pyrometry. On the basis of the normalized spectral emission distribution of char particles in the visible light region (390–710 nm) acquired by an Ocean2000 spectrometer, a calibrated normalized spectral emissivity model of burning chars was built. Then, the lookup table of the Nikon camera was further modified by this calibrated spectral emissivity model, enabling better predictions on char particle temperatures in cases of all different ambient conditions. The measurement deviation can be effectively reduced from 4.2 to 1.7% under ∼1800 K, from 9.5 to 2.2% under ∼2200 K, and from 8.8 to 0.9% under ∼2300 K.