Mass transfer in liquids

Lead Although subject to slight penetration at 980°C it shows no detrimental effects in stress rupture tests when tested in molten lead at this temperature or at 815°C . It is highly resistant to mass transfer in liquid lead as indicated by data obtained in tests at 800°C with a thermal gradient of 300°C . ... 

VOF or level-set models are used for stratified flows where the phases are separated and one objective is to calculate the location of the interface. In these models, the momentum equations are solved for the separated phases and only at the interface are additional models used. Additional variables, such as the volume fraction of each phase, are used to identify the phases. The simplest model uses a weight average of the viscosity and density in the computational cells that are shared between the phases. Very fine resolution is, however, required for systems when surface tension is important, since an accurate estimation of the curvature of the interface is required to calculate the normal force arising from the surface tension. Usually, VOF models simulate the surface position accurately, but the space resolution is not sufficient to simulate mass transfer in liquids. 

Jean-Claude Charpentier, Mass-Transfer Rates in Gas-Liquid Absorbers and Reactors Dee H. Barker and C. R. Mitra, The Indian Chemical Industry-lts Development and Needs Lawrence L. Tavlarides and Michael Stamatoudis, The Analysis of Interphase Reactions and Mass Transfer in Liquid-Liquid Dispersions... 

Groschel, L, Agar, D. W., Worz, O., Morgenschweis, K., The capillary-microreactor A new reactor concept for the intensification of heat and mass transfer in liquid-liquid reactions. Catalysis Today,... 

Leibson, I and BECKMANN, R. B. Chem. Eng. Prog. 49 (1953) 405. The effect of packing size and column diameter on mass transfer in liquid-liquid extraction. 

External mass transfer in liquid-solid systems... 

In connection with the interphase mass transfer in liquid-liquid and liquid-gas systems, the diffusion equations (and indeed all the equations of change) are valid in both phases. Hence, in principle, diffusion problems in a two-phase system may be solved by solving the diffusion equations in each phase and then choosing the constants of interaction in such a way that the solutions match up at the interface. It is customary to require that the following two conditions be fulfilled at the interface, in a system in which the solute is being transferred from phase I to phase II (1) the flux of mass leaving phase I must equal the flux of mass entering phase II if the diffusion... 

The overall coefficients of liquid-liquid mass transfer are important in the calculations for extraction equipment, and can be defined in the same way as the overall coefficients of gas-liquid mass transfer. In liquid-liquid mass transfer, one component dissolved in one liquid phase (phase 1) will diffuse into another liquid phase (phase 2). We can define the film coefficients /C i (nr h" ) and k (m h ) for phases 1 and 2, respectively, and whichever of the overall coefficients A (m h ), defined with respect to phase 1, or Al2 (mh ) based on phase 2, is convenient can be used. Relationships between the two film coefficients and two overall coefficients are analogous to those for gas-liquid mass transfer that is,... 

The first term in Equation 2.77 is the contribution due to overall longitudinal diffusion and the second term is contribution due to resistance to mass transfer in liquid phase. 

The third term of Equation 2.80 accounts for resistance to mass transfer in liquid phase. An obvious way of reducing this term is to reduce the liquid film thickness d. This causes a reduction in k and an increase in the term k1/(1 + k )2- However, using thinly coated column packings increases the probability of adsorption of solute molecules on the surface of support material, which might result in peaks tailing. 

Brauer (B16), 1958 Same as previous citation, but application to mass transfer in liquid films comparison with previous experimental work. 

In a MD process, a microporous hydrophobic membrane is in contact with an aqueous heated solution on the feed or retentate side. The hydrophobic nature of the membrane prevents the mass transfer in liquid phase and creates a vapor/liquid interface at the entrance of each pore. Here, volatile compounds (typically water) evaporate, diffuse and/or convert across the membrane, and are condensed and/or removed on the permeate or distillate side. 

S. Heinrich, L. Mori, Heat- and mass transfer in liquid-sprayed gas/solid fluidized beds, Proceedings, 11th International Drying Symposium (IDS 98), Halkidiki, Greece, August 19-22, 1998, Vol. A, pp. 414-421. 

Other known disadvantages of packed-bed reactors are low external and internal mass transfer rates. For trickle-bed reactors, a representative value for both and k/ig is 0.06 sec [18]. As was pointed out previously, the corresponding values for monolith reactors are higher due to the enhanced radial mass transfer in liquid slugs and to shorter diffusion length in both the liquid film and the solid catalyst. 

THE ANALYSIS OF INTERPHASE REACTIONS AND MASS TRANSFER IN LIQUID-LIQUID DISPERSIONS... 

These models represent the simplest approach to model mass transfer in liquid-liquid dispersions in that an effective interfacial surface area be-... 

The fundamental mechanisms for solute mass transfer in liquid-liquid extraction involve molecular diffusion driven by a deviation from equilibrium. When a liquid feed is contacted with a liquid solvent, solute transfers from the interior of the feed phase across a liquid-liquid interface into the interior of the solvent phase. Transfer of solute will continue until the solute s chemical potential is the same in both phases and equilibrium is achieved. 

Riede, Th. and Schlunder, E. U., Diffusivities of the Ternary Liquid Mixture 2-Propanol-Water-Glycerol and Three Component Mass Transfer in Liquids, Chem. Eng. Sci., 46, 609-617 (1991). 

Standart, G. L., Cullinan, H. T., Paybarah, A., and Louizos, N., Ternary Mass Transfer in Liquid-Liquid Extraction, AIChE J, 21, 554-559 (1975). 

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