An analytic model for the vapor-phase combustion of single metal particles is proposed. The condensation of vaporized oxides on the droplet surface and the motion of condensed oxides are properly accounted for. Three modes of vapor-phase combustion are possible depending on the direction of motion of the condensed oxides formed at the flame. Additional solutions, valid in dilute or enriched atmospheres, are obtained by allowing the flame temperature to decrease or increase, respectively. Flammability limits are also determined. Sample solutions are obtained for the combustion of A1 and Be with 02. It is shown that the mass burning rate and the flame stand-off distance are substantially increased by allowing for surface condensation. Be is found to burn much slower than Al, in addition to its tendency to accumulate substantial condensed oxides on the droplet surface. When results of the model are compared with available experimental observation, the agreement is reasonable, both qualitatively and quantitatively.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy(all)