Microstreamer dynamics during plasma remediation of NO using atmospheric pressure dielectric barrier discharges

Environmental concerns have resulted in the need for alternative energy efficient methods for the removal of oxides of nitrogen (NxOy) from atmospheric gas streams and among those techniques is plasma remediation. The devices typically used as plasma sources (corona and dielectric barrier discharges) operate in a filamentary mode which produces radicals and gas heating in narrow channels. Transport of radicals and products is therefore an important consideration in optimizing their efficiency. In this article we describe and present results for a radially dependent model of NxOy remediation in dielectric barrier discharges. We examine the consequences of localized energy deposition, and diffusive and advective radial transport, and determine how these spatial dependencies affect the energy efficiencies for NxOy removal. Local energy deposition in the streamer can produce high temperatures initiating advection and facilitating production of NO through N+O2→NO+O. Diffusion of NO into the streamer region from the bulk gas and advective transport of N outward into the bulk gas increase remediation of NxOy by channeling N into remediation, NO+N→N2+O, rather than radical reassociation, N+N+M→N2+M. Remediation efficiency generally decreases with increasing energy deposition due to the reassociation reaction and formation of NO. Transport of N out of and NO into the streamer region reduces this effect.