Combustion of nano-sized aluminum particles in steam: Numerical modeling

A model of the dynamics and mechanism of combustion of an ensemble of nanoscale aluminum particles in a steam is theoretically studied for adiabatic conditions. The formation of condensed phase is modeled for conditions when the homogeneous nucleation of gaseous Al2O3 species, processes of condensation/evaporation and coagulation of particles are taken into account. The model is used for studying the effects of the particle size, equivalence ratio, and chemical kinetics on the burning characteristics of aluminum-particle/steam mixtures. The calculated rate of combustion is limited by the rate of condensation growth of particles contained thermally unstable Al2O3 species. The details of the mechanism of interaction of the gas-phase reactions and the formation of particles are discussed. The results of numerical calculations are compared with experimental results of nano-aluminum dust combustion.