Initial Pressure and Mixture Composition Influence on LPG-air Confined Explosions

Values of some characteristic parameters of confined explosions for LPG (Liquefied Petroleum Gas)-air quiescent mixtures are examined in correlation with the initial pressure of fuel-air mixture and fuel/air ratio. The explosion pressures, the explosion times and the maximum rates of pressure rise were obtained from experiments made at ambient initial temperature in two closed vessels with central ignition: a spherical vessel (V = 0.52 L) and a cylindrical vessel (V = 1.12 L; diameter/height = 1.5) using mixtures with variable fuel content ([LPG] = 2.50 – 6.15 vol.%), at total initial pressures within 0.3 1.3 bar. For LPG – air at ambient initial temperature and pressure, the adiabatic explosion pressures and the flame temperatures of isochoric and isobaric combustion were calculated, assuming that chemical equilibrium is reached. The calculated and measured explosion pressures of LPG-air mixtures are compared and discussed taking into account the heat losses during explosion propagation in the two closed vessels.