Influence of inert additives on small-scale closed vessel explosions of propane-air mixtures

摘要

The propagation of deflagrations in a quiescent stoichiometric propane-air gaseous mixture diluted by 10 vol% of additive (Ar, N-2 or CO2) is experimentally studied in a small spherical vessel at various initial pressures (0.5-2.0 bar) and temperatures (298-423 K). The pressure evolution during centrally ignited explosions is characterised by the maximum explosion pressure p(ma)(x), the time to peak pressure and the maximum rate of pressure rise (dp/dt)(max). As expected, dilution leads to a decrease in peak explosion pressures and maximum rates of pressure rise, along with an increase in explosion times. Among the examined additives, CO2 has the most significant inerting effect, followed by N-2 and Ar. At constant temperature and mixture composition, the peak explosion pressures are linear functions of the total initial pressure. Both the slopes and intercepts of linear correlation p(max) = f(p(0)) are influenced by the amount of inert additive. The slopes depend on the heat of combustion of propane-air-inert mixtures corrected for the endothermic processes in the flame, whereas the intercepts are relevant for the amount of heat transferred to the explosion vessel before the end of combustion. Linear correlations are found for the (dp/dt)(max )versus initial pressure for all examined diluents.