Explosion Characteristics of NH3/CH3OH/Air Mixtures

In this work, the explosive combustion of NH3/CH3OH/air mixtures covering wide ranges of equivalence ratios (0.7–1.7) and CH3OH mole fractions (0.2–1.0) was investigated experimentally and theoretically at ambient temperature and pressure. Results showed that the addition of CH3OH increases the maximum explosion pressure and maximum pressure rise rate. The empirical correlations for the maximum explosion pressure and maximum pressure rise rate are proposed, respectively. Furthermore, the heat loss of the explosion decreases significantly with the increasing CH3OH mole fraction. According to the instability analysis, the tendency of flame instability is enhanced with the enrichment of CH3OH due to the promoted hydrodynamic instability. Besides, the maximum pressure rise rate is augmented by flame instability. Kinetic analysis indicates that the CH3OH addition enhances the net heat release rate and active radicals. The total heat release of the NH3/CH3OH/air explosion is mainly attributed to the reactions R3: OH + H2 ⇔ H + H2O, R11: HO2 + H ⇔ 2OH, R24: CO + OH ⇔ CO2 + H, and R284: NH3 + H = NH2 + H2, while the predominant endothermal reaction is R1: H + O2 ⇔ O + OH. With the addition of CH3OH, the chemical effect has the largest contributions to the accelerated flame propagation on the lean and stoichiometric side, while the contributions of thermal and transport effects are dominant on the rich side.