Effects of N2 and CO2 dilution on the explosion behavior of liquefied petroleum gas (LPG)-air mixtures.

The present work aims to provide theoretical support to prevent LPG explosion accidents and reduce its hazardous effect. The explosion of LPG-air mixtures (4.0 % - 9.0 % in volume) under N2 and CO2 dilution (0.0%-30.0% in volume) was experimentally investigated by using a 20-L vessel at ambient temperature and pressure. The parameters of the maximum explosion pressure (pmax), time to reach the maximum explosion pressure (tc), maximum rate of the pressure rise ((dp/dt)max), time to reach the maximum rate of the pressure rise (tb), and average velocity of flame propagation (v) were investigated. In addition, the inerting efficiencies of N2 and CO2 were compared and analyzed. The results show that there exists a cubic function relation among pmax,  (dp/dt)maxx,  tc, tb and LPG volume fraction during the LPG explosion process. At the volume fraction of LPG was 5.7 %, all parameters reached peak values. The addition of N2 and CO2 effectively suppressed the explosion of LPG, reduced pmax, (dp/dt)max, and v and extended tc and tb. At a low LPG volume fraction, the inerting efficiency of CO2 was higher than that of N2. At a high LPG volume fraction, the inerting efficiency of N2 was higher than that of CO2.