Explosion limits of hydrogen/oxygen mixtures with nitric oxide sensitization

The pressure–temperature explosion boundaries for H₂-O₂-NO mixtures were analyzed computationally. It is shown that, with the addition of NO to the H₂-O₂ mixture, the explosion limit maintains the non-monotonic Z-shaped response characteristic of H₂-O₂ explosions. As the addition of NO increases, the second explosion limit first moves toward lower temperatures and then reverts back to higher temperatures beyond 0.05% ~ 0.07% NO addition, with the third limit continuously moves toward the lower temperature side. Sensitivity analysis shows that, as the NO addition changes, the dominant reactions change at different pressures. The effects of wall termination reactions are also investigated by changing their reaction rates. Results show that, with increasing NO addition, the effect on the third limit weakens until it disappears.