Effect of Initial Pressure on the Lower Explosive Limit of Hybrid Mixtures

Standard explosion tests were performed in the 20 l sphere to investigate the effect of initial pressure on the lower explosion limit (LEL) of the hybrid niacin/acetone mixture. Dust concentrations were corrected on the basis of previously obtained computational results, to take into account the incomplete feeding of solid particles and their mal-distribution inside the sphere. Results have shown that, when moving from the low pressure range (P < 1 atm) to the high pressure range (P > 1 atm), the extension of the flammability region increases, and this has been attributed to the decreasing trend of the turbulence kinetic energy (and thus of the energy dissipation) with the initial pressure. Correlations for the LEL at both low and high pressures have also been developed.