Kinetic study of plasma-assisted n-dodecane/O₂/N₂ pyrolysis and oxidation in a nanosecond-pulsed discharge

The kinetics of low-temperature pyrolysis and oxidation of n-dodecane/O₂/N₂ mixtures in a repetitively-pulsed nanosecond discharge was studied experimentally and numerically. Time-resolved TD-LAS measurements, steady-state GC sampling, and mid-IR dual-modulation Faraday rotation spectroscopy measurements were conducted to quantify temperature as well as species formation and evolution. A plasma-assisted n-dodecane pyrolysis and oxidation kinetic model incorporating the reactions involving electronically excited species and NO_x chemistry was developed and validated. Results showed that a nanosecond discharge can dramatically accelerate n-dodecane pyrolysis and oxidation at low temperatures. The numerical model agreed well with experimental data for the major intermediate species. From the pathway analysis, electronically excited N₂* plays an important role in n-dodecane pyrolysis and oxidation. With addition of n-dodecane, NO concentration was significantly reduced, suggesting a strong NO kinetic effect on plasma-assisted low-temperature combustion via NO-RO₂ and NO₂-fuel radical reaction pathways. This study advances the understanding of the kinetics of plasma-assisted low-temperature fuel oxidation in N₂/O₂ mixtures.