LAUSR

Abstract Temperature measurement on propagating flame and thermogravimetric analysis have been conducted to investigate the mechanism of aluminum dust explosion, and a heterogeneous model is proposed to describe the oxidation of a single particle. The dust explosion experiments of nano-particle dust clouds exhibit higher rate of temperature increase and lower MEC than those of micron particle dust clouds. In addition, the MECs show inversely proportional to the measured rate of temperature increase. The model proposes two extreme conditions: whether the alumina film is involved in the reaction or not. The new methodology allows the estimation of oxidation kinetics of growing alumina. For micron particle, the model clarifies that the activation energy which has been wrongly considered to be for aluminum oxidation should be for lattice diffusion, and the initial reaction rate is proved to be dominated by the diffusion rate of oxygen through alumina shell as diffusion controlled reaction. For nano-particle, the model explained that why the reported activation energy shows significantly lower than that for micron particle, due to initially ignorable alumina film or considered as kinetically controlled reaction. However, as reaction occurs and alumina builds up on the surface, the interference of alumina somewhat increases the activation energy.