Explosion characteristics of H2/CH4/N2O at fuel-lean and stoichiometric conditions

Nitrous oxide has a wide range of applications, and the explosion in presence of nitrous oxide can cause serious disaster. In this study, we reported the explosion characteristics of hydrogen-methane-nitrous oxide mixtures with different equivalence ratios (phi) in a closed cylindrical explosion vessel at sub-atmosphere pressure (40 kPa). The equivalence ratio (phi) is defined as the ratio of the actual N2O-blended fuel ratio to the stoichiometric N2O-blended fuel ratio in this study. The key parameters were obtained experimentally which reflected the explosion characteristics such as the maximum explosion pressure, maximum pressure rise rate, and deflagration index. The results demonstrated that the experimental explosion pressure was greater than the adiabatic explosion pressure and N2O made explosion have potential of deflagration to detonation transition (DDT). The addition of methane increased the peak of both the maximum explosion pressure and the maximum pressure rise rate when the value of phi is constant. The effect of methane fraction on the maximum pressure rise rate was negligible when the equivalence ratio was higher than 0.6. In addition, with the increase of methane content, the equivalence ratio of the maximum explosion pressure peak would increase, but the peak of the pressure rise rate was stable at where the equivalence ratio is about 0.7.