A numerical model for the calculation of the minimum ignition energy of pure and mixture dust clouds

Abstract

A numerical model is developed for the minimum ignition energy (MIE) calculation of pure and mixture dust clouds, considering the influence of particle size distribution. The original particle number based size distribution is approximated with median sizes (number d50) of the subdivisions obtained by dividing the original distribution range. The MIE is calculated for 5 pure dusts, 2 mixtures of combustible dusts and 2 mixtures of combustible & inert dusts. For pure dust clouds, as the number of subdivisions and hence d50s increases, variation trend of the MIE as a function of dust concentration (MIE(conc)) gradually shifts from a “V” to a “U” or “bathtub” shape, along with an increase in the concentration where the dust cloud MIE (minimum MIE(conc) value) is reached. Furthermore, the calculated MIE fluctuates at lower number of d50s but gradually stabilizes as the d50 number further increases. The calculated MIE variation trends correspond well with the experimental data. However, due to uncertainties in the dust cloud formation and spark release in the experimental tests, differences in the definitions of the d50 in different studies and high idealization of the numerical model, there are deviations between the absolute experimental and calculated MIE values.