Numerical and experimental study of the explosion pressures and flammability limits of lower alkenes in nitrous oxide atmosphere

This article reports an experimental and numerical investigation of the explosive properties of flammable mixtures of lower alkenes in nitrous oxide atmospheres. The motivation for this study was to reduce fire/explosion risks in industrial facilities that handle nitrous oxide. In this study, explosion pressures and lower and upper flammability limits were experimentally determined at an initial temperature of approximately 20 °C and an initial pressure of 101.3 kPa. The lower alkanes/alkenes methane, ethane, n-butane, ethylene, and propylene were tested. To precisely estimate the upper flammability limits of alkane-alkene-N2O and alkene-alkene-N2O mixtures, we proposed a modified VAFT (variable adiabatic flame temperature) method. Experimental measurements and numerical calculations clearly demonstrated that (i) alkene-N2O mixtures exhibit higher explosion pressures than the corresponding alkene-O2 mixtures under fuel-lean conditions, (ii) Le Chatelier's equation successfully predicts the lower flammability limits of alkane-alkene-N2O and alkene-alkene-N2O mixtures, and (iii) the modified VAFT method can predict the upper flammability limits of alkane-alkene-N2O and alkene-alkene-N2O mixtures more accurately than Le Chatelier's equation.