Visualised combustion monitoring and mathematical modelling for moving magnesium particles in water vapour flow

Magnesium has received significant attention as a potential hydro-reactive metal particle fuel due to its superior ignition and combustion characteristics. In this work, a laser ignition testing system was designed for visualised combustion monitoring of moving magnesium particles with different average diameters. Combustion images were recorded and the effect of particle diameter on the combustion phenomena and combustion time were analysed. The statistical results show that the average combustion times are 4.5 ± 2.5, 15.2 ± 7.9, and 31.7 ± 17.9 ms for the magnesium particle fractions of 100, 150, and 200 µm, respectively. Moreover, a quasi-stable state, heterogeneous, and diffusion limited mathematical model was developed to describe the combustion process. In the model, a flame surface exists and divides the gas phase field between the particle surface and infinity into an internal zone and an external zone. Effects of particle relative movement on the heat transfer and external zone components were also considered.