Particle Equilibrium Composition model for iron dust combustion

Abstract

Flame propagation of iron powder in air is numerically studied. The present work introduces a chemical equilibrium model, which allows a detailed representation of the combustion products, phase transitions and detailed thermodynamics of the condensed phase. First, to validate the combustion of a single particle, numerical laser ignited single particle studies are performed and compared to experiments, where a very good agreement is obtained. A second series of simulations is performed on the propagation of laminar flames in iron/air mixtures for a wide range of equivalence ratios (ϕ= 0.2–1.8) using mono-dispersed particles having a diameter of 10 μm. Based on these simulations a multi-staged combustion process is identified, where each stage can be related to the formation of a different oxide. More importantly, the significance of including at least Fe3O4 in the model is demonstrated. This species contributes significantly to the burning velocity and flame temperature, as it is responsible for more than 25% of the total energy which can be released.