Shock-Tube Measurement and Kinetic Study of NO_2 promoting-effect on ethane ignition

摘要

Ignition delay times have been measured in a high-pressure shock tube for NO_2/C_2H_6/O_2/Ar mixtures at p of 1.2 - 20 atm-and T of 1050 - 1600 K. NO_2 is added to the stoichiometric baseline mixtures (neat ethane mixtures) as 30% and 100% of the ethane concentration by volume. The results indicate that NO_2 significantly promotes the ethane ignition 1) with higher NO_2 addition and 2) at higher pressure and lower temperature. Nevertheless, the NO_2 addition shows ignorable effect on the ethane ignition at lower pressure and higher temperature. A detail kinetic mode is developed against the data measured in this study and is used to perform sensitivity analysis and flux analysis. The kinetic analysis indicates that the interaction between NO_2 and ethane is very strong over the whole conditions investigated in this study. And the promoting-principle of NO_2 on the ethane ignition can be mainly attributed to two aspects: the first one is that reaction (NO + HO_2<=>OH + NO_2) converts the stable radicals HO_2 into the chain initiating OH radicals; the second one is that the presence of NO_2 accelerates the consumption of these stable fuels (C_2H_6, CH_4, CH_2O, CH_3) in the system.