A Heat and Mass Transfer Analysis of the Ignition and Extinction of Solid Char Particles

The present work studies the ignition and extinction of a spherical solid fuel particle exposed to a quiescent, hot, oxygen-containing environment. Using particle sizes and ambient temperature and oxygen concentration as parameters, the ignition, burning, and extinction of particles were parametrically analyzed by studying the relative heat production and heat-loss rates. For a given ambient condition, the results showed that it is possible that both large and small particles might not ignite at all. When a particle burns, its size decreases with time and its combustion characteristics are altered. The extinction condition may be reached due solely to the diminishing size of the particle. The particle extinction diameter was calculated. It strongly depends on the ambient condition and the reaction rate, but not on the initial particle size.