Explosion characteristics of H2/N2O and CH4/N2O diluted with N2

Abstract

In this study, we performed experiments in a closed cylinder vessel to investigate the explosion behaviors of H2/N2O and CH4/N2O mixtures with various equivalence ratios (φ) diluted with 40%, 50% and 60% N2. Explosion parameters, including the maximum explosion pressure, the explosion time, the maximum pressure rise rate, the deflagration index as well as the dimensionless pressure rise coefficients were derived and evaluated. Meanwhile, the adiabatic flame temperature and the laminar burning velocity were calculated. Lastly, the heat loss to the wall during the combustion process was computed. The results show that the explosion characteristics are influenced by the flame instability more significantly than the laminar burning velocity and the adiabatic flame temperature. The maximum explosion pressures of hydrogen- and methane- mixtures are found to be at φ = 0.8 and φ = 1.0, respectively. The minimum explosion time was attained at φ = 0.6–0.8 and φ = 1.0, and the inflection of the maximum pressure rise rate and the deflagration index occur at φ = 0.6–0.8 and φ = 0.8–1.0. The normalized pressure rise coefficients are relatively scattered at the fuel-lean side due to the highly unstable feature of N2O supporting explosions while at the fuel-rich side, the variations of the dimensionless coefficients are very small. Furthermore, the heat loss during the explosion also reaches its minimum value at the fuel-lean side.