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

Abstract

The present study investigates the kinetics of low-temperature pyrolysis and oxidation of n-dodecane/O2/N2 mixtures in a repetitively-pulsed nanosecond discharge experimentally and numerically. Time-resolved TDLAS measurements, steady-state gas chromatography (GC) sampling, and mid-IR dual-modulation Faraday rotation spectroscopy (DM-FRS) measurements are 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 NOx chemistry is developed and validated. The results show that a nanosecond discharge can dramatically accelerate n-dodecane pyrolysis and oxidation at low temperatures. The numerical model has a good agreement 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. The results also show that with addition of n-dodecane, NO concentration is reduced considerably, which suggests that there is a strong NO kinetic effect on plasma-assisted low-temperature combustion via NO-RO2 and NO2-fuel radical reaction pathways. This work advances the understandings of the kinetics of plasma-assisted low-temperature fuel oxidation in N2/O2 mixtures.