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Diffuse Surfaces

Here, D is the diffusion constant for heat or material and the kinematic viscosity of the liquid. A consequence of the existence of such a diffusive surface barrier is that the diffusion length = D/F is to be replaced by in all formulas, as soon as growth rate V the more important become the hydrodynamic convection effects. [Pg.903]

The emissivity of a material is defined as the ratio of the radiation per unit area emitted from a real or from a grey surface (one for which the emissitivity is independent of wavelength) to that emitted by a black body at the same temperature. Emissivities of real materials are always less than unity and they depend on the type, condition and roughness of the material, and possibly on the wavelength and direction of the emitted radiation as well. For diffuse surfaces where emissivities are independent of direction, the emissivity, which represents an average over all directions, is known as the hemispherical emissivity. For a particular wavelength X this is given by ... [Pg.441]

Since radiation arriving at a black surface is completely absorbed, no problems arise from multiple reflections. Radiation is emitted from a diffuse surface in all directions and therefore only a proportion of the radiation leaving a surface arrives at any other given surface. This proportion depends on the relative geometry of the surfaces and this may be taken into account by the view factor, shape factor or configuration F, which is normally written as F, for radiation arriving at surface j from surface i. In this way, F,y, which is, of course, completely independent of the surface temperature, is the fraction of radiation leaving i which is directly intercepted by j. [Pg.447]

The cases considered thus far have all been based upon the premise that one process, ash-layer diffusion, surface reaction, or gas-film mass transfer, is rate controlling. However, in some cases, more than one process affects the overall kinetics for the conversion of the solid. This has two implications ... [Pg.564]

In the absence of transport limitations, the processes of adsorption, surface diffusion, surface reaction, and desorption can be treated via the transition state theory (Baetzold and Somorjai, 1976 Zhdanov et al, 1988). For example, the application of the TST to a single site adsorption process,... [Pg.172]

Once the particulate sample has been removed from the airstream and deposited on a filter or an impaction-diffusion surface, the analyst can either remove the deposit from the surface and analyze the resulting gas or liquid or leave the deposit on the surface and analyze the surface and deposit together. [Pg.227]

For surface diffusion, one of the cross-sectional area s dimensions is 6, the thickness of the high-diffusivity surface layer, independent of system size. The remaining cross-sectional area length scales as A, and therefore Ab/As must scale as A. AVs/AVb scales as 1/A3. Therefore, substituting into Eq. 16.54,... [Pg.405]

MW = mean molecular weight of the vapor and noncondensable, lb/mole N = number of moles diffused, mole/hr pv = partial pressure of the vapor, atm Pt = total pressure, atm S = diffusion surface, ft2... [Pg.45]

Gas Solid S/G Adsorption, catalysis, corrosion, oxidation, diffusion, surface states, thin films, condensation and nucleation, permeation, energy transfer. [Pg.332]

Extension of the equilibrium model to column or field conditions requires coupling the ion-exchange equations with the transport equations for the 5 aqueous species (Eq. 1). To accomplish this coupling, we have adopted the split-operator approach (e.g., Miller and Rabideau, 1993), which provides considerable flexibility in adjusting the sorption submodel. In addition to the above conceptual model, we are pursuing more complex formulations that couple cation exchange with pore diffusion, surface diffusion, or combined pore/surface diffusion (e.g., Robinson et al., 1994 DePaoli and Perona, 1996 Ma et al., 1996). However, the currently available data are inadequate to parameterize such models, and the need for a kinetic formulation for the low-flow conditions expected for sorbing barriers has not been established. These issues will be addressed in a future publication. [Pg.130]

Chapter 8 provides a unified view of the different kinetic problems in condensed phases on the basis of the lattice-gas model. This approach extends the famous Eyring s theory of absolute reaction rates to a wide range of elementary stages including adsorption, desorption, catalytic reactions, diffusion, surface and bulk reconstruction, etc., taking into consideration the non-ideal behavior of the medium. The Master equation is used to generate the kinetic equations for local concentrations and pair correlation functions. The many-particle problem and closing procedure for kinetic equations are discussed. Application to various surface and gas-solid interface processes is also considered. [Pg.7]

Now possibilities of the MC simulation allow to consider complex surface processes that include various stages with adsorption and desorption, surface reaction and diffusion, surface reconstruction, and new phase formation, etc. Such investigations become today as natural analysis of the experimental studying. The following papers [282-285] can be referred to as corresponding examples. Authors consider the application of the lattice models to the analysis of oscillatory and autowave processes in the reaction of carbon monoxide oxidation over platinum and palladium surfaces, the turbulent and stripes wave patterns caused by limited COads diffusion during CO oxidation over Pd(110) surface, catalytic processes over supported nanoparticles as well as crystallization during catalytic processes. [Pg.434]

Figure 50 shows three examples for (different) kinetic situations in which bulk diffusion, surface reaction, and transport across a grain boundary are the sluggish steps. Nonetheless, the other parameters can also be evaluated. This becomes especially clear from the top figure, where the nonunity intercepts reveal surface effects. Similarly, the nonzero bending of the profiles in the other two figures indicates transport resistances. [Pg.102]


See other pages where Diffuse Surfaces is mentioned: [Pg.2768]    [Pg.258]    [Pg.445]    [Pg.275]    [Pg.1171]    [Pg.739]    [Pg.233]    [Pg.446]    [Pg.568]    [Pg.36]    [Pg.146]    [Pg.682]    [Pg.55]    [Pg.432]    [Pg.717]    [Pg.235]    [Pg.81]    [Pg.423]    [Pg.324]    [Pg.1006]    [Pg.110]    [Pg.95]    [Pg.118]    [Pg.170]    [Pg.547]    [Pg.649]    [Pg.730]    [Pg.391]    [Pg.34]    [Pg.125]    [Pg.394]    [Pg.706]    [Pg.188]    [Pg.4]    [Pg.45]    [Pg.447]    [Pg.350]   
See also in sourсe #XX -- [ Pg.113 ]




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Activation energy for surface diffusion

Activation energy surface diffusion

Adion surface diffusion

Adsorption Entropy on Heterogeneous Surfaces with Surface Diffusion

Adsorption surface diffusion

Alterations in Surface Films, Diffusion and Dissociation

Combined surface exchange/diffusion

Combined surface exchange/diffusion process

Competitive surface diffusion

Contributions of diffuse layer sorption and surface complexation

Dealloying surface diffusion

Density functional theory surface diffusion

Diffuse double layer ionic surface excesses

Diffuse layer model adsorption, 378 surface

Diffuse layer model metal surface complexation constants

Diffuse radiating surface

Diffuse reflectance laser flash-photolysis surface studies

Diffuse reflectance techniques, surface

Diffuse reflectance techniques, surface photochemistry studies

Diffuse temperature-programmed surface

Diffusion -hardened surfaces

Diffusion Boundary Layer Near the Surface of a Drop (Bubble)

Diffusion Boundary Layer Near the Surface of a Particle

Diffusion at surfaces

Diffusion coefficient from surface

Diffusion effects, surface

Diffusion electrode surface

Diffusion flat surface

Diffusion from permeate/membrane surface

Diffusion lateral surface

Diffusion length, surface

Diffusion ocean surface

Diffusion on surfaces

Diffusion on the Surface of a Micelle

Diffusion surface barriers

Diffusion surface evolution

Diffusion surface relaxation

Diffusion surface resistance

Diffusion surface transport

Diffusion surface treatments

Diffusion to surface

Diffusion vs. Surface Controlled Deposition

Diffusion with catalytic surface reaction

Diffusion with surface resistance

Diffusion, and surface exchange coefficients

Diffusion, bulk surface

Diffusion, definition surface

Diffusion, surface deterioration

Diffusion-convection layer near electrode surface

Diffusion-limited surface reaction

Effective surface diffusivity

Electrode surfaces diffusion-convection layer

Electrode surfaces reactant diffusion process

Electrodeposition surface diffusion

Flattening of Free Surfaces by Surface Diffusion

Gray diffuse surface

H and O surface diffusion

Homogenous surface diffusion model

Hydrogen Surface Diffusion on Homogeneous Metal Surfaces

Isothermal micropore pore-surface diffusion models

Lattice Diffusion from Particle Surfaces

Macropores, surface diffusion

Mass diffusion with catalytic surface reaction

Materials surface: diffusion

Maxwell-Stefan surface diffusion

Maxwell-Stefan surface diffusivities

Measurement of Diffusion and Surface Exchange Coefficients

Mechanisms of Surface Diffusion

Mesopores surface diffusion

Non-equilibrium surface forces of diffusion-electrical nature in

Photochemistry studies, surface, diffuse

Platinum electrodes surface diffusion

Pore Diffusion Resistance Combined with Surface Kinetics

Pore-surface diffusion model

Proton surface diffusion

Qualitative observations of vacancy-induced surface diffusion

Selective adsorption-surface diffusion

Selective surface diffusion membrane

Self-diffusion surface structure sensitivity

Self-diffusion, surface

Separation with Surface Diffusion and Capillary Condensation

Siliceous surface, variable-temperature diffuse reflectance Fourier transform

Silver surface diffusion

Sintering surface diffusion

Slow surface diffusion

Solid surfaces diffusion

Solid-state diffusion, surface evolution

Sorption processes surface diffusion

Specular and diffuse surfaces

Steady-state mass diffusion with catalytic surface reaction

Superficial velocity surface diffusion

Surface Diffusion Constant

Surface Diffusion and Entropy of Adsorbate

Surface Diffusion and Phase Formation

Surface Diffusion from Particle Surfaces

Surface Diffusion in Liquid-Filled Pores

Surface Reaction and Diffusion-Controlled Crack Growth

Surface and bulk diffusion of active particles

Surface chain diffusion

Surface charge density diffuse double layer

Surface charge diffusion

Surface complexation models diffuse layer model

Surface conditions, pure diffusion control

Surface density, diffuse double

Surface density, diffuse double layer

Surface diffusion

Surface diffusion

Surface diffusion 556 Subject

Surface diffusion Diffusivity

Surface diffusion Diffusivity

Surface diffusion Temperature dependence

Surface diffusion and capillary condensation

Surface diffusion and reactions

Surface diffusion anisotropic

Surface diffusion coefficients

Surface diffusion distance

Surface diffusion dynamics

Surface diffusion electrocatalysts

Surface diffusion exchange mechanisms

Surface diffusion jump lengths

Surface diffusion measurement

Surface diffusion mechanism

Surface diffusion model

Surface diffusion nature

Surface diffusion of ad-atoms

Surface diffusion of oxygen species on supported metal catalysts

Surface diffusion of reactant

Surface diffusion on metals

Surface diffusion parameters, table

Surface diffusion preexponential factor

Surface diffusion process

Surface diffusion random-walk analysis

Surface diffusion rate controlled proces

Surface diffusion rates, measurement

Surface diffusion rates, measurement applications

Surface diffusion rates, measurement principles

Surface diffusion rates, measurement theory

Surface diffusion separation

Surface diffusion separation types

Surface diffusion statistics

Surface diffusion vacancies

Surface diffusion, alumina

Surface diffusion, rapid alloying, microcluster

Surface diffusion/reaction coupling

Surface diffusivity

Surface diffusivity

Surface evolution by solid-state diffusion

Surface phenomena diffusion

Surface self-diffusion coefficient

Surface-diffusion-mediated deposition

Surfaces diffuse, grey

The relationship between diffusion constant and specific surface

The role of vacancies in surface diffusion

Thermal activation surface diffusion

Thermal surface diffusion

Transport coefficients surface diffusion coefficient

Transport mechanism, membranes surface diffusion

Transport mechanisms surface diffusion

Underground Storage of Helium Diffusion through a Spherical Surface

Vacancy-induced surface diffusion

With surface diffusion

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