To achieve high efficiency in pulverized coal combustion furnace and burner, the detailed estimation of the burn-off time and thermal behavior of pulverized coal particles is important. The volume reaction and unreacted core models have been employed as solid-gas reaction model for a pulverized coal particle. Moreover, the possibility that the heat of reaction generated on the particle surface does not fully contribute as heating source to the coal particle should be considered. In this study, the heat and mass transfer around a single pulverized coal char particle exposed to a simplified heating environment are numerically analyzed to investigate the influence of the different coal ranks in their reactivity, coal char particle diameter, and reaction models for the burn-off time and thermal behavior of the pulverized coal particle. From the sensitivity analysis of the reaction models for the burn-off time, the importance of model selection when dealing the coal char particle with high reaction rates is indicated.

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During ablation experiments in an arc-heated facility, the presence of spalled particles has been observed upstream of a detached shock wave or a stagnation-point boundary layer. In the past experiments using spectroscopic measurement for nitrogen arc-jet, the CN violet band spectra owing to the spallation particles ejected from the ablator were observed upstream of the shock layer. Based on this fact, in this study, the flight path of a single spallation particle ejected into a nonequilibrium flow field is numerically analyzed and the particle properties are obtained. The simulation is carried out about a solid particle ejected vertically from the front surface of an ablator, including various initial speeds, sizes, and positions. Moreover, by classifying the obtained results, the particle behavior is carefully investigated and the possibility of a particle being observed upstream of a shock wave is discussed.

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