Nitrogen Oxide Effect on Hydrogenous Mixture Self-Ignition

7 Nitrogen Oxide Effect on Hydrogenous Mixture Self-Ignition 

Interest in the nitrogen oxide effect on hydrogenous mixture self-ignition has been brought up by some conclusions made in [53] that compounds like NOx (for example, NO) are inhibitors of self-ignition at temperatures lower than 1,100 K and pressures higher than 0.03 MPa. The predictions [53] were contradicted by measured data in [54]. The pressure and temperature zones presented in [53, 54] and supplemented by data obtained in [55] are outlined in Fig. 6.13. It is seen that most data were measured in a zone of limited practical use. 

Let us describe the characteristics of NO and NO2 effects on H2 + air selfignition delay. Our description is based on data calculated with the 42 H2 reactions 

It is seen that a small amount of NO reduces the self-ignition delay time. The maximum promoting effect was measured at about 0.5% NO by volume. At more than 5% NO by volume, the enhancing effect on self-ignition was not seen. At pressures lower than 1 MPa the NO effect on the process is negligible. 

The diagram in Fig. 6.15 illustrates the effect of 0.5 vol.% of NO on at various temperatures. The self-ignition enhancing effect is characteristic for moderately high temperatures and it is not observed at T 1,350 K. 

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