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  • Articles  (17)
  • porous media  (12)
  • oxidation
  • Springer  (17)
  • American Chemical Society
  • 1995-1999  (17)
  • Technology  (17)
  • 1
    Electronic Resource
    Electronic Resource
    Tetrachlorosilane Consumption in Radio Frequency Glow Discharge (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 509-533 
    Details
    ISSN: 1572-8986
    Keywords: RF SiCl4 discharge ; mass spectrometry ; kinetics ; decomposition ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Time-resolved mass spectrometry was used for analysis of the plasma reactions in radio frequency (RF) SiCl 4 and SiCl 4 −O 2 discharges as functions of starting partial pressure and electrical power. Molecular concentrations of the reactants and products from SiCl 4 alone and with O 2 were obtained from the mass spectra and used for plotting the kinetic curves. The SiCl 4 and O 2 consumption rates were calculated from the kinetic curves and compared with results of theoretical simulation of the reaction. Direct electron impact decomposition was found to be the main pathway for pure SiCl 4 conversion. On the contrary, the consumption of SiCl 4 in the SiCl 4 +O 2 mixtures was largely chemical. The experimental macrokinetics are in agreement with a model in which oxidation is caused by the atomic oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021811316740
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  • 2
    Electronic Resource
    Electronic Resource
    Oxidation of Styrene in a Silent Discharge Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 131-151 
    Details
    ISSN: 1572-8986
    Keywords: Styrene ; oxidation ; silent discharge ; plasma ; dielectric barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A silent discharge plasma reactor has been developed to study the oxidation of styrene vapor in argon/oxygen mixtures. A number of analytical techniques were employed to determine the destruction efficiency and to characterize the intermediate products. The destruction efficiency was measured as a function of initial styrene concentration, temperature, and energy density of the plasma. The formation of solid products was observed in most experiments. At low temperature (100°C), the solid deposit was polymeric in nature, while at high temperature (300°C) the solid appeared to be amorphous carbon. A combination of high temperature and high energy density resulted in high destruction efficiency and minimal production of solid films. The destruction efficiency vs. energy density is shown to be more complex than a simple model predicting exponential behavior. Several reasons for the discrepancy are suggested. The “e-folding” energy density for the destruction of styrene is compared to literature values for other organic compounds, measured using similar types of plasma reactors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021812201545
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidation of Dilute Benzene in an Alumina Hybrid Plasma Reactor at Atmospheric Pressure (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 383-394 
    Details
    ISSN: 1572-8986
    Keywords: Nonthermal plasma ; benzene ; Al2O3 ; BaTiO3 ; oxidation ; absorption ; atmospheric pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The combination of plasma discharge and adsorption was examined for oxidation of dilute benzene in air in a plasma reactor packed with a mixture of BaTiO 3 pellets and porous Al 2 O 3 pellets (i.e., an alumina hybrid reactor). The oxidative decomposition of benzene was enhanced by the benzene concentrating on the Al 2 O 3 pellets. Furthermore, there was a higher selectivity to CO 2 in the products from the hybrid than from a plasma reactor packed with BaTiO 3 pellets alone. The presence of the Al 2 O 3 pellets suppressed the formation of N 2 O.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021820403362
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidation and Reduction Processes During NO x Removal with Corona-Induced Nonthermal Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 421-443 
    Details
    ISSN: 1572-8986
    Keywords: Streamer corona ; NO x removal ; nonthermal plasma ; oxidation ; reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper, the NO-to-NO 2 conversion in various gaseous mixtures is experimentally investigated. Streamer coronas are produced with a dc-superimposed high-frequency ac power supply (10–60 kHz). According to NO x removal experiments in N 2 +NO x and N 2 +O 2 +NO x gaseous mixtures, it is supposed that the reverse reaction NO 2 +O→NO+O 2 may not only limit NO 2 production in N 2 +NO x mixtures, but also increase the energy cost for NO removal. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N+NO→N 2 +O, induce negligible NO removal provided the O 2 concentration is larger than 3.6%. With adding H 2 O into the reactor, the produced NO 2 per unit removed NO can be significantly reduced due to NO 2 oxidation. NH 3 injection could also significantly decrease the produced NO 2 via NH and NH 2 - related reduction reactions. Almost 100% of NO 2 can be removed in gaseous mixtures of N 2 +O 2 +H 2 O+NO 2 with negligible NO production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021824504271
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  • 5
    Electronic Resource
    Electronic Resource
    Porous Media and the Bénard–Marangoni Problem (1997)
    Springer
    Transport in porous media 27 (1997), S. 327-355 
    Details
    ISSN: 1573-1634
    Keywords: surface tension ; porous media ; Marangoni–Bénard ; instability.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The Rayleigh–Bénard instability for a clear fluid has its equivalent for a liquid saturated porous matrix. The phenomenological Darcy momentum law cannot give rise by itself to an instability analogous to that of Bénard–Marangoni, but the Brinkman model at least allows it. A critical Marangoni number exists leading to cellullar patterns and, for realistic values of the permeability, it is proportional to the inverse of this last parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006564129233
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  • 6
    Electronic Resource
    Electronic Resource
    Universal Correlation of Nitrogen 1s and Oxygen 1s Photoelectron Binding Energies with Chemical Composition in Nitrogen-Containing Plasma Polymers (1999)
    Springer
    Plasmas and polymers 4 (1999), S. 283-307 
    Details
    ISSN: 1572-8978
    Keywords: Plasma polymers ; oxidation ; XPS ; photoelectron binding energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The incorporation of oxygen into nitrogen-containing plasma deposited polymers was studied by X-ray Photoelectron Spectroscopy (XPS). As the oxygen content of the plasma polymer increased, the binding energy of the N 1s photoelectrons increased. Conversely, the binding energy of the O 1s photoelectrons was inversely proportional to the nitrogen content of the plasma polymer. The data from a large number of samples all obeyed the same “universal” correlations of photoelectron binding energy versus chemical composition. The data were described by the same curve regardless of whether the oxygen was incorporated rapidly into the thin film during plasma deposition or whether the oxygen was added slowly during spontaneous oxidation of the film in air. This implies that the same thermodynamic principles of radical reactions governed the addition of oxygen to the plasma polymer. The shift in the O 1s and N 1s photoelectron binding energies as a function of chemical composition was used to monitor the proximity of nitrogen and oxygen. By contrasting the experimental data with a simple binomial model which described the random addition of oxygen to a lattice containing carbon and nitrogen, we were able to show that oxygen was preferentially added near nitrogen-containing groups in plasma polymers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021831527895
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  • 7
    Electronic Resource
    Electronic Resource
    Wave Dynamics of Saturated Porous Media and Evolutionary Equations (1999)
    Springer
    Transport in porous media 34 (1999), S. 117-128 
    Details
    ISSN: 1573-1634
    Keywords: porous media ; Biot's theory ; nonlinear waves ; asymptotic methods ; evolutionary equations.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract Nonlinear wave dynamics of an elastically deformed saturated porous media is investigated following the Biot approach. Mathematical models under research are the Biot model and its generalization by consideration of viscous stresses inside liquids. Using two-scales and linear WKB methods, the classical Biot system is transformed to a first-order wave equation. To construct the solution of the other system, an asymptotic modified two-scales method is developed. Initial system of equations is transformed to a nonlinear generalized Korteweg–de Vries–Burgers equation for quick elastic wave. Distinctions of wave propagation in the context of the Biot model and its generalization are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006557307278
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  • 8
    Electronic Resource
    Electronic Resource
    Experimental investigation of characteristic length scale in periodic heterogeneous porous media (1996)
    Springer
    Transport in porous media 25 (1996), S. 235-246 
    Details
    ISSN: 1573-1634
    Keywords: experiment ; porous media ; periodic heterogeneity ; characteristic length scale ; scale-dependent dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract An experimental investigation of scale-dependent dispersion in periodic heterogeneous porous media was conducted. Models with two-, three- and four-layer periodic heterogeneities were constructed to investigate the effect of heterogeneity size on the scale-dependence of dispersion. Longitudinal dispersion coefficients were determined as a function of column length by measuring the breakthrough of a continuous injection of potassium chloride tracer solution. Chloride ion concentration was monitored by recording the millivolt potential of silver/silver chloride electrodes placed at intervals along the length of the column. In all three models, dispersion appeared to be scale dependent up to a distance of approximately 20–30 times the size of the repeated heterogeneity group (hydraulic unit). Because all three models suggested a similar dependence, it was concluded that a medium with periodic heterogeneity may likely be characterized by the scale of its hydraulic unit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00135858
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  • 9
    Electronic Resource
    Electronic Resource
    Convective Flows on Reactive Surfaces in Porous Media (1998)
    Springer
    Transport in porous media 33 (1998), S. 279-293 
    Details
    ISSN: 1573-1634
    Keywords: surface reactions ; critical points ; convective flow ; porous media ; Darcy flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A model for the convective flow in a fluid‐saturated porous medium containing a reactive component is considered. This component undergoes an exothermic reaction (modelled by a first order mechanism) on an impermeable bounding surface, the resulting heat released driving the convective flow. Large Rayleigh number flow near a stagnation point is treated in detail by first considering the steady states. Multiple solution branches and critical points arising from a hysteresis bifurcation are identified. The form that these solution branches take depends on whether or not the effects of reactant consumption are included. An initial‐value problem is then discussed. This shows that both the lower (slow reaction) and upper (fast reaction) solution branches are stable (and the ultimate state of the system). When the parameter values are such that there is no steady state, the solution develops a finite‐time singularity, the nature of which is analysed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006541819777
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  • 10
    Electronic Resource
    Electronic Resource
    Saturated Compressible and Incompressible Porous Solids: Macro- and Micromechanical Approaches (1999)
    Springer
    Transport in porous media 34 (1999), S. 101-115 
    Details
    ISSN: 1573-1634
    Keywords: porous media ; macro-and microscopic approches ; compressible and incompressible incompressible fluid ; incompressible fluid ; effective stress concept.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In this paper two complementary approaches are used to describe the mechanical behavior of saturated compressible and incompressible porous solids. The macroscopic investigation is based on the mixture theory, restricted by the volume fraction concept. In the micromechanical approach, a hierarchy of conditionally ensemble averaged fluid and solid phase momentum balance equations are derived for a simple model of quasi-static liquid saturated porous media. The ensemble averaged equations for both the phases agree remarkably well with the macroscopic results. A micromechanical basis for Terzhagi's effective stress concept is presented. In addition, an expression for additional partial solid stress modifying the effective stress principle, to account for deformability of solid materials, is also derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006505323208
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  • 11
    Electronic Resource
    Electronic Resource
    A new numerical scheme for convective dominated heat transfer in a porous medium with strong temperature gradients (1995)
    Springer
    Transport in porous media 21 (1995), S. 101-122 
    Details
    ISSN: 1573-1634
    Keywords: discretization scheme ; numerical heat transfer ; porous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A new numerical scheme, theimplicit correction scheme, has been developed for heat transfer in a porous medium with strong temperature gradients. The scheme includes diffusion, convection and transverse heat transfer processes. By using correction coefficients which are based on transverse heat transfer, the effects of convection enthalpy flow and diffusion are modified. Under suitable limiting conditions, the implicit correction scheme can be reduced to the central-difference, upwind, or power-law scheme. The correction scheme is shown to be especially useful in calculations of the thermal effectiveness of the regenerator in Stirling cycle refrigeration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613751
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  • 12
    Electronic Resource
    Electronic Resource
    Mixed convection in a porous medium produced by a line heat source (1995)
    Springer
    Transport in porous media 18 (1995), S. 1-13 
    Details
    ISSN: 1573-1634
    Keywords: Mixed convection ; thermal plume ; line source ; porous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A boundary-layer analysis is presented for the mixed convection flow which is produced when a horizontal line heat source, which is embedded in an infinite fluid-saturated porous medium, generates heat at a constant rate. It is shown that the governing equations can be non-dimensionalized so that they do not involve any parameters and thus just one solution of the transformed boundary-layer equations is required. Series solutions which are valid both near the line source and far downstream are obtained and compared with the numerical solution of the full boundary-layer equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00620657
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  • 13
    Electronic Resource
    Electronic Resource
    Single Phase Flow in Partially Fissured Media (1997)
    Springer
    Transport in porous media 28 (1997), S. 285-306 
    Details
    ISSN: 1573-1634
    Keywords: fissured media ; homogenization ; dual porosity ; modeling ; microstructure ; porous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract Totally fissured media in which the individual cells are isolated by the fissure system are effectively described by double porosity models with microstructure. Such models contain the geometry of the individual cells in the medium and the flux across their interface with the fissure system which surrounds them. We extend these results to a dual-permeability model which accounts for the secondary flux arising from direct cell-to-cell diffusion within the solid matrix. Homogenization techniques are used to construct a new macroscopic model for the flow of a single phase compressible fluid through a partially fissured medium from an exact but highly singular microscopic model, and it is shown that this macroscopic model is mathematically well posed. Preliminary numerical experiments illustrate differences in the behaviour of solutions to the partially fissured from that of the totally fissured case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006562120265
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  • 14
    Electronic Resource
    Electronic Resource
    Effects of thermal dispersion and stratification on combined convection on a vertical surface embedded in a porous medium (1996)
    Springer
    Transport in porous media 25 (1996), S. 275-282 
    Details
    ISSN: 1573-1634
    Keywords: combined convection ; porous media ; heat transfer ; thermal stratification ; thermal dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The effects of thermal dispersion and thermal stratification on mixed convection about a vertical surface in a porous medium are studied. The conservation equations that govern the problem are reduced to a system of nonlinear ordinary differential equations. The resulting equations are solved on the basis of the local similarity approximation. The results indicate that both dispersion and stratification effects have considerable influence on the heat transfer rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00140984
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  • 15
    Electronic Resource
    Electronic Resource
    Mixed Convection Effect on Melting from a Vertical Plate in a Porous Medium (1999)
    Springer
    Transport in porous media 36 (1999), S. 245-254 
    Details
    ISSN: 1573-1634
    Keywords: porous media ; heat transfer ; mixed convection.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In the present work, the effect of mixed convection about vertical surfaces on the phenomenon of melting process in a fluid-saturated porous medium is analyzed on the basis of boundary layer approximations. Similarity solutions are obtained for aiding external flow. The final similarity equations are integrated numerically by use of the fourth-order Runge–Kutta method. Results are reported for the flow and thermal fields in the melt region. The melting phenomenon decreases the local Nusselt number at the solid–liquid interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006566924390
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  • 16
    Electronic Resource
    Electronic Resource
    On the Modelling of Generalized Taylor–Aris Dispersion in Chromatographs via Multiple Scales Expansions (1999)
    Springer
    Transport in porous media 36 (1999), S. 307-339 
    Details
    ISSN: 1573-1634
    Keywords: dispersion ; chromatography ; porous media ; adsorption ; homogenization ; multiple scales expansions.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract This paper is devoted to the computation of effective equations for the transport of a solute in a chromatograph. We focus our attention on models that retain dispersion effects. A chromatograph is a biporous periodic heterogeneous medium, made up of macropores, and of small porous adsorbing crystals that have a retention effect on the solute. We use the method of multiple scales expansions. Various macroscopic behaviours appear, according to the respective orders of magnitude of the dimensionless characteristic parameters: Peclet number in the macropores, ratio of the characteristic time of diffusion in the macropores to the characteristic time of diffusion in the crystals, adsorption coefficient. Dispersion occurs for a Peclet number of order ε−1. We then discuss the effective behaviour of the solute, with respect to the orders of magnitude of the other characteristic parameters. To our knowledge, most of the models are new. Our modelling is not restricted to chromatographs. It applies to various situations of physic and chemical engineering: fixed bed reactors, catalytic cracking, ground water for instance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006654621514
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  • 17
    Electronic Resource
    Electronic Resource
    A new application of the reciprocity relations to the study of fluid flows through fixed beds (1998)
    Springer
    Journal of engineering mathematics 33 (1998), S. 103-112 
    Details
    ISSN: 1573-2703
    Keywords: creeping flow ; Brinkman's equation ; porous media ; array of spheres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract Creeping flow through an array of spheres with small volume fraction φ is studied theoretically. It is observed that it can be described macroscopically by Brinkman's equation. A generalized version of the reciprocity relations is used to determine the viscous term up to O(φ2) for the case of random configuration and up to O(φ3) for the case of periodic, cubic configurations of the fixed bed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004299402988
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