Interfacial transport

The fluxes at the gas-liquid interfaces (Ar, ) are obtained by equating the fluxes in the gas and liquid films. Moreover, a thermodynamic equilibrium is assumed to prevail at the interface. According to Pick s law, the flux is obtained from a simple two-film expression (Chapters 6 and 7)  

The exchange of substance between the liquid bulk and the network (N[-) is described by the phenomenological equation 

It should be noted that the transfer coefficient (fcnet) is not a pure mass transfer coefficient, but it is also dependent on the exchange flow rate through the network. Principles similar to those of Kunii and Levenspiel for fluidized beds are thus applied (Chapter 5). 

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W. Shyy, H. S. Udaykumar, M. M. Rao, R. W. Smith. Computational Fluid Dynamics with Moving Boundaries in Series in Computational and Physical Processes in Mechanics and Thermal Sciences. Washington, DC Taylor Francis, 1995 W. Shyy. Computational Modeling for Fluid Flow and Interfacial Transport. Amsterdam Elsevier, 1994. 

Ultrasound could play a dual role of creating higher interfacial area as well as facilitating the process of interfacial transport. This phenomenon seemed to be responsible for the increase in the colour intensity of the solution of Al3+-aluminon adsorption complex and could be explained as follows. 

The volatilization of low-molecular-weight by-products from molten PET can be described by using the classical two-film model or the penetration theory of interfacial transport [95],... 

Shyy, W. 1994. Computational modeling for fluid flow and interfacial transport. New York Elsevier. 

Chapter 9 Air-Water Mass Transfer in the Field. The theory of interfacial mass transfer is often difficult to apply in the field, but it provides a basis for some important aspects of empirical equations designed to predict interfacial transport. The application of both air-water mass transfer theory and empirical characterizations to field situations in the environment will be addressed. 

While the viscous sublayer may be important for momentum transport, it is everything for mass and heat transport through liquids. Virtually the entire concentration boundary layer is within the viscous sublayer This difference is important in our assumptions related to interfacial transport, the topic of Chapter 8, where mass is transported through an interfacial boundary layer. 

Interfacial transfer of chemicals provides an interesting twist to our chemical fate and transport investigations. Even though the flow is generally turbulent in both phases, there is no turbulence across the interface in the diffusive sublayer, and the problem becomes one of the rate of diffusion. In addition, temporal mean turbulence quantities, such as eddy diffusion coefficient, are less helpful to us now. The unsteady character of turbulence near the diffusive sublayer is crucial to understanding and characterizing interfacial transport processes. 

It may seem as though we have abandoned our statement that the unsteady aspects of the interaction of the diffusive sublayer and turbulence are paramount, because Kb, Kl, and Kg are all bulk quantities. However, the unsteady relationships that exist will still be brought into the analysis of equation (8.10) and (8.11) (i.e., 5 = 8 D, turbulance)). This relatively simple characterization provides for most of the research regarding interfacial transport rates. 

Eqns. (3.4-1) to (3.4-3) are practical for describing interfacial transport in combination with transfer coefficients. The use of transfer coefficients is a simplification that involves the linearization of gradients over the boundary layer. Let us assume that a solid dissolves from a non-porous plate into a flowing fluid that sweeps the surface. According to the boundary layer theory, there is a smooth transition between the immobile fluid located on the plane up to the bulk of the fluid that moves with a uniform velocity. In this layer, the three transfer processes... 

Vroman 44) has recently demonstrated the great importance of volume and concentration in limiting interfacial transport and thus in influencing the adsorption process (see also Sect. 4.6),... 

D.A. Edwards, H. Brenner and D.T. Wasan, Interfacial Transport Processes and Rheology, Butterworth-Heineman Publishers, Stoneham, MA, 1991. 

Impurities (including surfactants, hydrates, solvates, complexes, and reactive additives) can greatly inLuence the rate of dissolution by modifying the crystal habit or by interfering with the interfacial transport of solute from the crystal to the bulk solution. 

Reactive absorption, distillation, and extraction have much in common. First of all, they involve at least one liquid phase, and therefore the properties of the liquid state become significant. Second, they occur in moving systems, thus the process hydrodynamics plays an important part. Third, these processes are based on the contact of at least two phases, and therefore the interfacial transport phenomena have to be considered. Further common features are multicomponent interactions of mixture components, a tricky interplay of mass transport and chemical reactions, and complex process chemistry and thermodynamics. 

In the diffusive interfacial transport-refractive index (DIT-NDX) method, compositions are determined using precise refractive index data (8). Refractive index data valid to +/- 0.00005 are obtainable using the DIT apparatus vithin an area of 30 ym2 in a sample approximately 25-ym thick (0.75 picoliter volume). Data collection and analysis require 9 seconds. The accuracy, spatial resolution, and speed vith vhich refractive indices can be determined are thus superb. 

Free-surface flow with interfacial transport processes is a subject of great interest since its effects can be seen both in nature and practical devices, such as the air-sea interface, ship wakes, and chemical processes like gas-absorption equipment. In many cases, it is necessary to investigate the interaction of the flow and the free surface or correlate the free-surface deformation with the flow characteristics beneath the liquid surface. To this end, PIV technique can be applied to some free-surface flows as a powerful experimental tool. 

Edwards, D.A., Brenner, H. and Wasan, D.T. (1991) Interfacial Transport Processes and Rheology. Butterworth-Heinemann, Boston. 

The variation in rate-determining step with coadsorbed species was noted by Bond in his recent review (9). Bond cited the extensive evidence that spillover (passage from the metal to the support) can be rate determining. For systems where H20 (or other sorbed species) promotes spillover, it may do so by increasing the interfacial transport, a potentially slow step in the process. 

To access the potential influence of spillover on catalysis and interfacial transport, more qualitative studies are required. Further, it is, for instance, necessary to isolate the individual steps in the phenomena and account for the reaction kinetics of the process. As an example, what is the difference between inter- and intraparticle transport on the support ... 

As long as the entropy changes are large, Eq. (6.269) cannot be linearized. For example, chemical reactions and interfacial transport between two phases yield large entropy changes. Statistical rate theory leads to well-defined coefficients that can be measured or controlled and hence the criteria for linearization may be explicitly expressed. 

Gas-liquid Reasonable Turbulence modeling -1- modeling of interfacial transport phenomena -1- prediction of flow regime transition -1- interaction of hydrodynamics with chemical transformation processes... 

Trickle bed reactors Slurry reactors Three-phase fluidized beds No Little Little Modeling on basis of unit cell approach + development of correspondence rules for macroscopic system behavior Modeling of the effect of the solids phase on interfacial transport phenomena Modeling of the effect of the solids phase on interfacial transport phenomena -I- development of refined models for particle-particle and particle-wall interaction... 

Rudzinski W. and Panczyk T., Kinetics of Gas Adsorption in Activated Carbons, Studied by Applying the Statistical Rate Theory of Interfacial Transport, J. Phys. Chem. B., 105(2001) pp.68S8-6866. 

Rudzinski W., Borowiecki T., Panczyk T., and Dominko A. A quantitative approach to calculating the energetic heterogeneity of solid sur ces from an analysis of TPD peaks Comparison of the results obtained using the absolute rate theory and the statistical rate theory of interfacial transport, J. Phys. Chem. B, 104 (2000) pp. 1984-1997. 

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