Combustion and spontaneous extinction of porous carbon particles in nitrogen–oxygen mixtures at room temperature

The effect of the initial temperature of a porous carbon particle on the characteristics of its combustion and spontaneous extinction is analyzed taking into account Stefan flow and heat loss by radiation. It is shown that in the case of forced ignition (increase in the initial temperature of the particle), the diameter and density of the particle after spontaneous extinction remain virtually unchanged. As a result, the extinguished particles have the same diameter but different density. It is shown that the dependence of particle diameter on stationary temperature can be used to determine the maximum combustion temperature and diameter of the particle during its spontaneous extinction. The effect of oxygen concentration on the region of ignition of a porous carbon particle, determined by the initial diameter and temperature of the particle, is analyzed. Analysis of the diffusion-kinetic relations shows that each of the two main heterogeneous reactions of carbon oxidation make similar contributions to the heat and mass transfer of the particle with the surrounding.