Numerical and experimental investigation of light emissions of a planar nitrogen atmospheric-pressure dielectric barrier discharge due to addition of ammonia considering oxygen impurity

Abstract

In this paper, the mechanisms of light emissions, including NO-γ , NO-β and N 2-SPS, produced in a N 2 /NH 3 atmospheric-pressure dielectric barrier discharge considering realistic oxygen impurity (30 ppm) are investigated numerically and experimentally. Self-consistent, one-dimensional fluid modeling is used to numerically simulate the discharge process with 48 species and 235 reaction channels. An optical emission spectrometer (OES) is used to measure the relative intensities of the light emission. The simulations of the light emission intensities for the above-mentioned OES lines generally reproduce the trends observed in the experiments caused by changes in the NH 3 concentration. All of the predicted intensities of NO-γ , NO-β and N 2-SPS decrease with increasing amount of NH 3 caused by various reaction mechanisms. The former is due to the loss of N 2 (A) and NO(A) by the reaction of NH 3 with N 2 (A) and NO(A), respectively. The decrease in NO-β is due to the depletion of N and O because of NH 3 , and the decrease in N 2-SPS is due to electron attachment to NH 3 and a weaker metastable-metastable associative ionization of N 2. All of the simulated results demonstrate that the discharges are typically Townsend-like because the ions outnumber the electrons and the electric field across the gap is distorted only slightly by the charged particles during the breakdown. Finally, a reduced chemical kinetics model for a planar atmospheric-pressure N 2 /O 2 /NH 3 dielectric barrier discharge is proposed and validated by benchmarking against the above complete chemical kinetics. This results in a reduced chemical kinetics consisting of 33 species and 87 reactions with a very limited loss of accuracy of discharge properties, while it is 2.1 times faster in computational time as compared with the complete version.

NO reduction using low-temperature SCR assisted by a DBD method

“…Recently, a combination of the NH 3 -SCR method and the DBD technique has been of interest for application in low-temperature SCR processes [6,25,26], for example, Guan et al found that the combination of NH 3 -SCR and a non-thermal plasma enhanced the overall reaction and allowed for an effective removal of NO x at 100 °C [6], and Wang et al studied NO removal in a plasma-catalyst system over CuCe/ZSM-5 catalysts and observed the highest NO and NO x removal efficiencies of 90.7% and 80.1% [26]. However, there are few reports concerning the denitration reaction mechanism and the effect of extra oxidation of NH 3 induced by the active particles in the DBD plasma system, and the optimum operation conditions for NO x removal is also needed to be cleared using the NH 3 -SCR system assisted by DBD [27,28]. As the most widely used catalyst in practical business applications, the typical V 2 O 5 -WO 3 /TiO 2 catalyst shows high performance only within the narrow temperature window of 300-450 °C [6].…”