in Wiley InterScience (www.interscience.wiley.com).A noncontact, color-band pyrometer, based on widely available, inexpensive digital imaging devices, such as commercial color cameras, and capable of pixel-by-pixel resolution of particle-surface temperature and emissivity is demonstrated and described. This diagnostic instrument is ideally suited to many combustion environments. The devices used in this method include color charge-coupled device (CCD), or complementary metal oxide semiconductor (CMOS) digital camera, or any other color-rendering camera. The color camera provides spectrally resolved light intensity data of the image, most commonly for three color bands (Red, Green, and Blue,), but in some cases for four or more bands or for a different set of colors. The CCD or CMOS sensor-mask combination has a specific spectral response curve for each of these color bands that spans the visible and often near infrared spectral range. A theory is developed, based on radiative heat transfer and camera responsivity that allows quantitative surface temperature distribution calculation, based on a photograph of an object in emitted light. Particle surface temperature calculation is corrected by heat transfer analysis with reflection between the particle and reactor wall for particles located in furnace environments, but such corrections lead to useful results only when the particle temperature is near or below the wall temperatures. Wood particle-surface temperatures were measured with this color-band pyrometry during pyrolysis and combustion processes, which agree well with thermocouple measured data. Particle-surface temperature data simultaneously measured from three orthogonal directions were also mapped onto the surface of a computer generated 3-D (three-dimensional) particle model.
A new approach to modeling NO X under oxy-fuel combustion conditions in a simple staged-oxidizer flow field is presented. The approach is centered on the combination of devolatilization and char oxidation models with a detailed kinetic mechanism for light hydrocarbon combustion. NO X chemistry is included by the user's selection of the detailed mechanism, while the devolatilization model consists of the chemical percolation devolatilization (CPD) model modified to be independent of oxidizer composition. Literature-based correlations provide elemental composition of the volatiles. Model predictions were compared to experimental measurements with good agreement in several respects. The model provides insights for the interpretation of experimental oxy-fuel combustion NO X results, and recommendations are given for computational fluid dynamics (CFD) modeling of NO X in oxy-fuel combustion.
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