Numerical and experimental investigation of nanosecond-pulsed plasma activated C₂H₄/O₂/Ar mixtures in a low temperature flow reactor

The present work combines numerical and experimental efforts together to investigate the effect of low temperature, nano-second pulsed plasma discharges on the oxidation of C₂H₄/O₂/Ar mixtures at 60 Torr pressure. The non-equilibrium plasma discharge is modeled by a two-temperature framework with detailed chemistry-plasma mechanism. The model shows that 75%~77% of input pulse energy was consumed in electron impact dissociation, excitation and ionization reactions, which efficiently produces significant amount of important radical species, fuel fragments and several excited species. The trends of numerical and experimental results agree well. The results from 1D model are compared with 0D model and it show that 1D model in general agrees better with experiments than 0D model. The modeling results reveal that reactions between O(¹D) and hydrocarbons are importantly affecting the formation of C₂H₆, CH₂CO, CH₂O, CO, CO₂, H₂O₂, H₂O, O₂(α¹Δ_g) and O₂(b¹Σ⁺_g). Due to the persistent relatively high level of O₂(α¹Δ_g) and O₂(b¹Σ⁺_g), C₂H₂ converts into HCO directly without the need of going through the intermediate species of HCCO, CH₂* and CH₂ in the case without plasma. Owing to the long lifetime of O₂(α¹Δ_g), this effect can last to 3.1 sec after the finish of all 150 pulses.