Predictions of soot formation and its effect on the flame temperature of a pulverized coal-air turbulent jet

The distributions of soot volume fraction, soot number density, and soot particle size in a coal-air turbulent jet flame was numerically investigated using a soot formation model developed in our previous study. In addition, the effect of radiation from different radiative media on the flame temperature was assessed and discussed. Validated by the reported experimental measurements, the distribution of soot volume fraction in the turbulent air-coal jet flame was well predicted. It was also found that soot particles were formed and accumulated in the high temperature zone with remarkable oxygen deficient. In the same time, the temperature of the coal-air jet flame was reduced remarkably by soot radiation but barely by soot formation. For the simulated flame, at a downstream location of 200 mm from the jet exit, the heat loss caused by the thermal radiation of coal particles, soot particles and gas species resulted in a temperature decrease of 262 K, 238 K and 102 K respectively. Different radiative media induced remarkably different distributions of absorption coefficient, and the emitting heat loss from the media was determined by the local absorption coefficient and temperature.

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