Influence of Pulse Repetition Frequency on CH 4 Dry Reforming by Nanosecond Pulsed Dielectric Barrier Discharges

In this paper, the effect of pulse repetition frequency (PRF) on CH 4 dry reforming by nanosecond pulsed dielectric barrier discharge (DBD) is evaluated by a zero-dimensional (0D) chemical kinetics model. The calculated conversions and product yields agree well with the reported experimentally measured results. The simulation results indicate that the vibrationally excited CH 4 and CO 2 molecules have negligible contributions to the CH 4 and CO 2 conversions with PRF from 3 to 100 kHz. However, their role in the CH 4 and CO 2 conversions increases due to accumulation with 1 MHz PRF. The relaxation time of CH 4 ( v 24 ) is considered to be around 1 μs, and the relaxation time of CH 4 ( v 13 ) and CH 4 (e) is in the range of several hundred ns. The relaxation time of CO 2 vibrationally excited states is between 1 μs and 10 μs, and the relaxation time of CO 2 electronically excited state is within tens of ns. The increase in PRF promotes CO 2 and CH 4 conversions, with growth rates of CO and H 2 yields much greater than that of C 2 H 6 and C 3 H 8 yields. As the PRF increases from 3 to 10 kHz, the production of CO and H 2 is mainly caused by the electron impact dissociations of CO 2 and CH 4 , respectively. Inversely, the major hydrocarbon products, C 2 H 6 and C 3 H 8 , are primarily produced via reactions among neutral species and consumed via electron impact dissociation reactions. This phenomenon suggests that the promotion of PRF on electron impact reactions is much greater than its benefits in reactions between neutral species.