C.N. Gray

Bio: C.N. Gray is an academic researcher from University of Leeds. The author has an hindex of 1, co-authored 1 publications receiving 204 citations.

A numerical model of the zonally averaged dynamical and chemical structure of the middle atmosphere

Abstract: A two-dimensional, time-dependent model has been constructed to study the zonally averaged structure of the middle atmosphere (16–116 km) allowing interaction among dynamics, radiation and photochemistry. The zonally averaged dynamics are governed by a stream function equation for the residual Eulerian meridional circulation wherein the effects of wave transience and dissipation have been neglected. The resulting circulation is thus driven by diabatic heating and cooling, with Rayleigh friction introduced to balance the momentum budget. The temperature structure is computed from the zonal mean thermodynamic equation, while the appropriate continuity equations are solved to determine the distribution of the various chemical species and families. In the chemical continuity equations, two types of eddy transport processes are present in addition to the transport by the residual Eulerian circulation. Small-scale disturbances are assumed to produce turbulent mixing which is modeled in terms of horizontal and vertical diffusion coefficients, while steady state planetary waves give rise to fluxes which are expressed in terms of observed wave structure and the photochemical lifetime of the species transported. The circulation, temperature structure, and distribution of chemical constituents obtained with the model are for the most part in satisfactory agreement with observations. In particular, the direct, equator-to-pole circulation computed for the stratosphere seems to be capable of explaining the major features of the distribution of trace constituents there, although the effect of the Fickian diffusion included in the model is important in determining the magnitude of gradients.

Chemical Kinetics Database and Predictive Schemes for Nonthermal Humid Air Plasma Chemistry. Part II. Neutral Species Reactions

Abstract: Reliable kinetics data are necessary input for models describing the decomposition of gases in electric discharge or electron-beam devices In this second part of a continuing series, we provide a core database describing the dominant reactions of neutral species in nonthermal low temperature (300–700K) pulsed plasmas containing humid air Recommended rate constants and extrapolation methods are provided in a manner to facilitate prediction of reactivities as a function of temperature and pressure

Reaction chemistry and optimization of plasma remediation of NxOy from gas streams

Abstract: Increasing environmental awareness and regulatory pressure have motivated investigations into energy efficient methods to remove oxides of nitrogen (NxOy) from gas streams resulting from the combustion of fossil fuels. Plasma remediation of NxOy is potentially an efficient removal technique due to the relative ease of generating reactants by electron‐impact processes. Previous works have investigated the use of electron‐beam, corona, and dielectric barrier discharge (DBD) generated plasmas for this purpose. In those works, reduction (N+NO→N2+O) and oxidation (NO2+OH→HNO3) reactions were identified as major removal channels. A computational study of the plasma remediation of NxOy from humid air using repetitively pulsed DBDs is reported. The dominant reaction pathways are discussed and scaling laws are proposed to optimize the energy efficiency of removal. Three reaction periods are identified: the current pulse (during which electron‐impact processes generate radicals), the postpulse remediative period (d...