Showing papers on "Mass transfer published in 1984"
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01 Jan 1984
TL;DR: In this article, Mass Transfer Fundamentals and Mass Transfer Coefficients are presented. But they do not consider the effect of the number of contacts in the process of transferring a gas to a liquid.
Abstract: 1. Mass Transfer Fundamentals. 2. Diffusion Coefficients. 3. Formulation of Mass Transfer Models. 4. Partial Differential Equations of Diffusion. 5. Mass Transfer Coefficients. 6. Convective Mass Transfer. 7. Phase Equilibrium. 8. Adsorption. 9. Binary Distillation. 10. Multicomponent Distillation. 11. Extraction. 12. Mass Transfer in Continuous Differential Contactors. 13. Design of Staged Columns. 14. Adsorption. Appendix A: Viscosity of Gases and Liquids. Appendix B: Equilibrium Data. Appendix C: Equilibrium K-Values. Appendix D: Enthalpy Data. Appendix E: Unit Conversion Factors and Constants.
341 citations
01 Jan 1984
TL;DR: In this paper, the authors use the volume averaging method to derive the governing equations for heat and mass transport in a rigid porous medium, which involve spatial derivations of the temperature and concentration and suitable representations of these deviations are required in order to obtain a closure.
Abstract: In this article we use the method of volume averaging to derive the governing equations for heat and mass transport in a rigid porous medium. These equations involve spatial derivations of the temperature and concentration and suitable representations of these deviations are required in order to obtain a closure. In our approach, the closure is based on the governing differential equations for the spatial deviations and it allows for the direct determination of the transport coefficients that appear in the volume-averaged equations. These calculated coefficients are compared with experimental measurements for the following cases: diffusion and reaction in porous media, heat conduction in two-phase systems, dispersion of a non-adsorbing solute and thermal dispersion in a packed bed. For conductive and diffusive transport, excellent agreement between theory and experiment is found using the spatially periodic model of a porous medium. The comparison between theory and experiment for convective processes indicates that the details of the structure of a real porous medium are important and not adequately described by the spatially periodic models used in this study.
330 citations
01 Jan 1984
TL;DR: The role of bubbles in gas transfer from water to air at higher wind speeds has been investigated in this article, where a simple model for bubble contribution to gas exchange has been proposed to estimate the contribution of bubbles to gas transfer across an air-water interface.
Abstract: 1. Physico-Chemical Fundamentals.- Physical-chemical phenomena and molecular properties.- The determination of Henry's Constant for volatile organics by equilibrium partitioning in closed systems.- Volatilization of chlorinated hydrocarbons from water.- The ratio of gas-phase to liquid-phase mass transfer coefficients in gas-liquid contacting processes.- Absorption of gases at condensing and evaporating water surfaces.- The effects of evaporation and condensation on an absorption process.- 2. Turbulence near Gas-Liquid Interfaces.- Turbulence structure and turbulent diffusion near gas-liquid interfaces.- Turbulence measurements near the free surface in stirred grid experiments.- A laboratory technique for investigating the relationship between gas transfer and fluid turbulence.- Carbon dioxide transfer at the gas/water interface as a function of system turbulence.- Turbulence structure of wavy stratified air-water flow.- Current fluctuations in the surface waters of small lakes.- Moisture and heat transport in a stably stratified boundary layer over a water surface.- 3. Interfacial Motions and Instabilities.- Wind-wave effects on gas transfer.- Interfacial motion observed during experiments on air-water gas transfer.- A laboratory study of the velocity field below surface gravity waves.- The roles of Langmuir circulations in gas transfer across natural water surfaces.- Measurements of the fluctuating pressure in the turbulent boundary layer over progressive, mechanically generated water waves.- Experimental studies of surface wave breaking and air entrainment.- Bubbles produced by breaking wind waves.- The role of bubbles for gas transfer from water to air at higher windspeeds. Experiments in the wind-wave facility in Hamburg.- A new optical bubble measuring device A simple model for bubble contribution to gas exchange.- Contribution of bubbles to gas transfer across an air-water interface.- Entrapment and transport of bubbles by plunging water.- 4. Conceptual Models and Parameterizations of Gas Transfer.- Conceptual models of gas exchange.- A comparison of turbulent mass transfer at gas-liquid and solid-liquid interfaces.- The variation of the gas transfer coefficient with molecular diffusity.- Wind/wave-tunnel experiment on the Schmidt number - and wave field dependence of air/water exchange.- A model of interfacial gas transfer for a well-roughened sea.- Turbulent transfer across smooth and rough surfaces.- Reaeration of open channel flow.- Dependence of oxygen transfer rate on energy dissipation during surface aeration and in stream flow.- Wind effects on air-water oxygen transfer in a lake.- Reaeration and wind induced turbulence shear in a contained water body.- 5. Field and Laboratory Experimental Techniques.- Field techniques for reaeration measurements in rivers.- Gas transfer rate coefficient measurement of wastewater aeration equipment by a stable isotope krypton/lithium technique.- Reaeration studies on some New Zealand rivers using methyl chloride as a gas tracer.- Dichlorodifluoromethane (Freon-12) as a tracer for nitrous oxide release from a nitrogen-enriched river.- An assessment of the radiotracer technique for measuring reaeration rates in large river systems.- Measurements of wind effects on water-side controlled gas exchange in riverine systems.- Optimum application of the radon deficit method to obtain air-sea gas exchange rates.- Parametrization of air/lake gas exchange.- Simultaneous in situ determination of dissolved gases by gas chromatography.- 6. Climate and Oceanographic Applications.- Gas exchange measurements in natural systems.- The role of oceanic whitecaps in air-sea gas exchange.- On the exchange of oxygen and carbon dioxide between ocean and atmosphere in an eastern boundary current.- Invasion of fossil fuel CO2 into the ocean.- In situ pH measurements as an indicator of CO2 gas transfer in glacial meltwaters.- The transfer of mercury at the air/water interface.- Exchange rates of dimethyl sulfide between ocean and atmosphere.- Laboratory observations on transfer of atmospheric oxygen into stratified seawater.- 7. Water Quality and Engineering Applications.- The significance of gas exchange in water quality assessment and planning.- The sensitivity of the dissolved oxygen balance to predictive reaeration equations.- Estimation of volatilization of toxics for multimedia modeling.- Reaeration measurement in swamp streams: Radiotracer case studies.- Prediction of dissolved gas transfer in spillway and outlet works stilling basin flows.- Carbon dioxide desorption from the activated sludge at the waste water treatment plants.- Volatilization of fission products in nuclear reactor buildings.- Self-propelled weir aerators.
226 citations
TL;DR: In this article, the effects of different gas-and liquid-phase models on the vaporization behavior of a single component isolated droplet are studied for both stagnant and convection situations in a high-temperature gas environment.
Abstract: : The effects of different gas- and liquid-phase models on the vaporization behavior of a single-component isolated droplet are studied for both stagnant and convection situations in a high-temperature gas environment. In conjunction with four different liquid-phase models, namely, d2 law, infinite conductivity, diffusion limit, and internal vortex circulation, the different gas-phase models include a spherically symmetric model in the stagnant case and Ranz-Marshall correlation plus two other axisymmetric models in the convective case. A critical comparison of all these models is made. The use of these models in a spray situation is examined. A transient one-dimensional flow of an air- fuel droplet mixture is considered. It is shown that the fuel vapor mass fraction can be very sensitive to the particular liquid- and gas-phase models. The spherically symmetric conduction or diffusion limit model is recommended when the droplet Reynolds number is negligible compared to unity, while the simplified vortex model accounting for internal circulation is suggested when the droplet Reynolds number is large compared to unity. Keywords include: Spray; Droplet; Evaporation; Combustion; Modeling.
157 citations
TL;DR: In this article, data from an injection experiment for chloride and several cations indicate significant influence of solutestreamed processes on transport in a mountain stream, interpreted in terms of transient storage processes for all tracers and sorption processes for the cations.
Abstract: Solute transport in streams is determined by the interaction of physical and chemical processes. Data from an injection experiment for chloride and several cations indicate significant influence of solutestreambed processes on transport in a mountain stream. These data are interpreted in terms of transient storage processes for all tracers and sorption processes for the cations. Process parameter values are estimated with simulations based on coupled quasi-two-dimensional transport and first-order mass transfer sorption. Comparative simulations demonstrate the relative roles of the physical and chemical processes in determining solute transport. During the first 24 hours of the experiment, chloride concentrations were attenuated relative to expected plateau levels. Additional attenuation occurred for the sorbing cation strontium. The simulations account for these storage processes. Parameter values determined by calibration compare favorably with estimates from other studies in mountain streams. Without further calibration, the transport of potassium and lithium is adequately simulated using parameters determined in the chloride-strontium simulation and with measured cation distribution coefficients.
154 citations
TL;DR: In this paper, the authors measured the gas holdups, volumetric mass transfer coefficients, and specific gas-liquid interfacial areas in CMC solutions using a bubble column of diameter 0.305 m and height 3.4 m.
Abstract: Until now the oxygen transfer in viscous non-Newtonian solutions has been studied only in bubble columns of about 0.14-m diameter. Recently Godbole et al. (1982) reported much smaller gas holdups in Carboxy Methyl Cellulose solutions (CMC) for a large-diameter column. Therefore, the gas holdups, volumetric mass transfer coefficients, and specific gas-liquid interfacial areas are measured in CMC solutions using a bubble column of diameter 0.305 m and height 3.4 m. The transition from churn-turbulent to slug flow regime occured at higher viscosities and the gas holdups and volumetric mass transfer coefficients were lower in both flow regimes than reported for smaller column diameters. Empirical correlations are presented for the gas holdup, volumetric mass transfer coefficient, and specific gas-liquid interfacial area which would be suitable for the design of fermentors.
152 citations
TL;DR: In this paper, a two-resistance mass transfer model has been developed based on film resistance and homogeneous solid phase diffusion for Basic Blue 69 dye onto silica in a batch adsorption system.
134 citations
TL;DR: In this paper, it was shown that only a fraction of the dissolved gas is transformed into bubbles at the electrode, expressed as the efficiency of gas evolution, increases as the current density increases but is far smaller than unity in usual industrial current density values and remains different from unity in the whole range of nucleate gas evolution.
107 citations
TL;DR: An analytical solution for a two resistance mass transfer model explaining the adsorption of Astrazone Blue dye (Basic Blue 69) onto Sorbsil silica has been developed.
Abstract: An analytical solution for a two resistance mass transfer model explaining the adsorption of Astrazone Blue dye (Basic Blue 69) onto Sorbsil silica has been developed. The model includes a film mass transfer coefficient, kf1 = 80 × 10−6cm·s−1, and an internal effective diffusivity, Deff = 18×10−9cm2·s−1 which controls the internal mass transport processes based on a pore diffusion mechanism.
106 citations
TL;DR: In this article, a theoretical analysis is presented for temperature-programmed desorption (TPD) from a bed of catalyst perfused by a flow of carrier gas, where the bed is modeled either as a single CSTR or as multiple CSTR's connected in series.
88 citations
TL;DR: In this paper, the authors measured the Fischer-Tropsch liquid fractions as functions of temperature (373 − 523 K), pressure (1 − 4 MPa) and stirrer speed (800 − 1100 rev min −1 ) in a mechanically agitated and surface-aerated vessel.
TL;DR: In this paper, the stability of the cylindrical interface between the vapor and liquid phases of a fluid is studied when the vapor is hotter than the liquid and the two phases are enclosed between two cylinders coaxial with the interface, and when there is a mass and heat transfer across the interface.
Abstract: The Kelvin–Helmholtz stability of the cylindrical interface between the vapor and liquid phases of a fluid is studied when the vapor is hotter than the liquid and the two phases are enclosed between two cylindrical surfaces coaxial with the interface, and when there is a mass and heat transfer across the interface. Both axisymmetric and asymmetric disturbances are considered. A comparison of the results obtained here with those for the corresponding problem with plane geometry reveals that the plane geometry configuration is more stable than the cylindrical one, and, contrary to the case of Rayleigh–Taylor instability problem, the heat and mass transfer has a destabilizing influence on the system.
TL;DR: In this article, a theory is proposed for predicting the transfer of a gas through a fluidized bed of small particles to a large particle, which enables prediction of the Sherwood number (Nsh, the dimensionless mass transfer coefficient).
TL;DR: In this article, it is shown that spontaneous interfacial motions appear at an interface between two immiscible phases in a state far from equilibrium, e.g., an aqueous phase of an organic acid or a complex ion and an organic phase of a long-chain surfactant molecule.
Abstract: Spontaneous interfacial motions appear at an interface between two immiscible phases in a state far from equilibrium, e.g. an aqueous phase of an organic acid or a complex ion and an organic phase of a long-chain surfactant molecule. The instabilities observed are related to variations in the interfacial tension. It is shown that they resemble the well known Marangoni effect by considering interfacial convection and the coupling between diffusion and convection fluxes, but they differ by the presence of chemical reactions. The notion of assisted desorption is defined in order to interpret the experiments.The analysis of this phenomenon could be useful in determining the optimal conditions for obtaining convective interfacial transfer to enhance liquid–liquid extraction processes.
TL;DR: In this paper, analytical solutions have been developed for the problem of solute transport in a steady, three dimensional field of groundwater flow with non-equilibrium mass transfer of a radioactive species between fluid and solid phases and with anisotropic hydrodynamic dispersion.
01 Mar 1984-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, a model for alloy solidification is presented, which follows the growth of the solid-liquid zone adjacent to the chill face, the movement of the zone across the mold, and the region of final solidification adjacent to centerline.
Abstract: The analysis is applicable to alloy solidification which proceeds horizontally to the center of a mold. The model follows the growth of the solid-liquid zone adjacent to the chill face (the initial transient), the movement of the zone across the mold, and the region of final solidification adjacent to the centerline (the final transient). During solidification the density of the liquid varies across the twophase zone. Consequently, there is natural convection which is treated as flow through a porous medium. The equations for convection are coupled with the equation of solute redistribution between the phases in order to calculate macrosegregation after solidification is complete. Results were computed for alloys which show: (1) “inverse segregation≓ at a cooled-surface; (2) macrosegregation resulting from solidification with the initial transient, a period with a complete two-phase zone, and a final transient; and (3) macrosegregation when the width of the two-phase zone exceeds the semi-width of the mold.
TL;DR: In this paper, a theoretical analysis of the combined heat and mass transfer process taking place in the absorption of a gas or vapor in a turbulent liquid film is presented, where Eddy diffusivity correlations have been used to describe the transport near the wall and the interface and in the bulk of the film.
TL;DR: In this paper, an open-cycle absorption chiller with solar heated air passing through a packed column to which the dilute solution is supplied is described, followed by a theoretical study of heat transfer and water vapor transfer rates.
Abstract: Reconcentration of a lithium chloride solution in an open-cycle absorption chiller can be accomplished by passing solar heated air through a packed column to which the dilute solution is supplied. Following a theoretical study of heat transfer and water vapor transfer rates in the column, experimental measurement of those rates was made. Heat transfer and mass transfer coefficients are correlated with rates of air and liquid flow, and with temperatures of air and liquid supply. Performance data are presented and commercial design and operating requirements are suggested.
TL;DR: In this article, experimental investigations of the technical reaction kinetics of various AB5 alloys are presented and it is shown that it is equally important to improve both the hydrogen flow and the heat transfer in a reaction bed.
Abstract: Periodically operating absorption engines, i.e. absorption heat pumps, heat transformers and refrigerators based on metal-hydrogen reactions, are becoming of great interest in technical applications. In order to keep the material inventory small and to design compact machines, short cycle times are necessary. In this paper, experimental investigations of the technical reaction kinetics of various AB5 alloys are presented and it is shown that it is equally important to improve both the hydrogen flow and the heat transfer in a reaction bed.
TL;DR: In this paper, the authors measured the interfacial area and liquid-side mass transfer coefficients in a 5cm diameter trickle-bed reactor operating with organic liquids. But their results were limited to the case of CO 2 -NaOH and O 2 −Na 2 SO 3.
TL;DR: In this article, an analytical model based on the method of characteristics is presented for the calculation of one-dimensional (1D), three-component condensing and vaporizing gas drives, which describes mass transfer between oil and gas, swelling and shrinkage, viscosity and density changes, gravity stabilization, and rock/fluid interaction.
Abstract: An analytical model based on the method of characteristics is presented for the calculation of one-dimensional (1D), three-component condensing and vaporizing gas drives. The model describes (1) mass transfer between oil and gas, (2) swelling and shrinkage, (3) viscosity and density changes, (4) gravity stabilization, and (5) rock/fluid interaction. The main assumptions of the model are local thermodynamic equilibrium and the absence of dispersion, diffusion, and capillarity. Example calculations are presented that bring out the main features of both condensing and vaporizing gas drives and also indicate the importance of mass transfer between the phases. In the special case of ''developed miscibility'', the model predicts a piston-like displacement having a complete recovery at gas breakthrough. The main applications of the model are in (1) conceptual studies of gas drives in which mass transfer plays an important role and (2) the calibration and checking of numerical reservoir simulators for multicomponent, multiphase flow.
TL;DR: In this article, a monolithic palladium catalyst was used for liquid-phase hydrogenation of nitrobenzoic acid, and the total effectiveness of the catalyst was enhanced due to the fact that the mass transfer in the channels of the monolith was increased by the segmented gas-liquid flow.
Abstract: Liquid-phase hydrogenation of nitrobenzoic acid was performed in a monolithic palladium catalyst The total effectiveness factor of the catalyst was enhanced due to the fact that the mass transfer in the channels of the monolith was increased by the segmented gas-liquid flow The effectiveness factor was shown to be much higher than for a trickle bed under corresponding reaction conditions A mathematical model for the mass transfer in the segmented gas-liquid flow derived and found to describe the phenomena well
TL;DR: In this paper, a kinetic treatment of interfacial reactions was proposed that considers the individual processes of all the species involved in mass transfer between liquid phases, together with a new method for the determination of individual transport coefficients, leads to an efficient concept of resistances and to the possibility of treating chemically coupled systems.
Abstract: Interfacial reactions during reactive mass transfer between liquid phases are the central point of this contribution. In order to go from the general problem to identify the site of the reaction and the rate-controlling step, a kinetic treatment of interfacial reactions is proposed that considers the individual processes of all the species involved. This concept, together with a new method for the determination of individual transport coefficients, leads to an efficient concept of resistances and to the possibility of treating chemically coupled systems (coextraction). Finally, the pronounced effects of adsorption layers are discussed with respect to diffusional- and interfacial-controlled mass transfer.
TL;DR: In this paper, a novel experimental technique for measuring volumetric mass transfer coefficients in a stirred autoclave reactor is proposed, based on pursuing the instationary pressure drop due to mass transfer under isochoric conditions.
Abstract: A novel experimental technique for measuring volumetric mass transfer coefficients in a stirred autoclave reactor is proposed. The method is based on pursuing the instationary pressure drop due to mass transfer under isochoric conditions. The usefulness of the technique is demonstrated for the Fischer-Tropsch slurry system.
TL;DR: In this article, a model is developed for calculation of simultaneous heat and mass transfer processes in vertical bubble absorbers as used for ammonia-water absorption refrigeration systems, and the mass transfer coefficients resulting from these experiments are correlated by a modified Sherwood relation.
Abstract: A model is developed for calculation of simultaneous heat and mass transfer processes in vertical bubble absorbers as used for ammonia-water absorption refrigeration systems. Some preliminary experiments have been performed in an absorber without heat removal. The results from these experiments are compared with the literature and give a first indication about the methods for prediction of the absorption process. Experiments have also been performed with simultaneous heat removal. The internal diameters of the absorbers tested were 10.0, 15.3, and 20.5 mm. The mass transfer coefficients resulting from these experiments are correlated by a modified Sherwood relation. An interative procedure is presented which allows design of vertical tubular bubble absorbers for ammonia-water absorption refrigeration systems.
TL;DR: In this article, a theory is developed on the premise that streams move in plug flow with all resistance to motion confined to a thin lubricating layer at the strean-continuum interface.
TL;DR: In this article, the authors measured the desorption rate of carbon dioxide from supersaturated water solutions into pure carbon dioxide or nitrogen gas stream in a baffled vessel with a flat gas-liquid interface operated in a continuous manner.
Abstract: The rates of desorption of carbon dioxide from supersaturated water solutions into pure carbon dioxide or nitrogen gas stream were measured at 15,25, and 35°C in a baffled agitated vessel with a flat gas-liquid interface operated in a continuous manner. The volumetric liquid-phase mass transfer coefficients for the bubbles generated in the agitated liquid and the enhancement factors of the volumetric liquid-phase mass transfer coefficient for the free liquid surface due to the bubbling were calculated from the measured desorption rates and correlated as functions of the relative supersaturation of the solution and the liquid-phase Reynolds number.
TL;DR: In this article, the one dimensional transient heat conduction equation is solved with convective surface boundary condition, during air-cooling, and a calculation scheme is proposed in which, up to half the cooling time, the calculation is made with both heat and mass transfer from the product surface, thereafter it is continued with heat transfer only.
Abstract: The one dimensional transient heat conduction equation, in spherical co-ordinates, is solved with convective surface boundary condition, during air-cooling. The enthalpy potential concept is used to include the cooling effect of desiccation. A calculation scheme is proposed in which, up to half the cooling time, the calculation is made with both heat and mass transfer from the product surface, thereafter it is continued with heat transfer only. The calculated temperatures for apples and potatoes are compared with the measured values available in the literature, and good agreement is observed.
01 Dec 1984-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the mass transfer coefficient characterizing the rate of dissolution of immersed carbon rods depends both on the absolute values of the melt velocity and on the local values of turbulence intensity; thus significant mass transfer will occur in the region of the eye of the circulation, where the absolute value of the mean velocity is small.
Abstract: Experimental measurements are reported on melt velocities and on the rate at which immersed carbon rods dissolve in a 4-ton induction furnace, holding a low carbon steel melt. These measurements are compared with theoretical predictions, based on the numerical solution of Maxwell’s equations and the turbulent Navier-Stokes equations. In general, good agreement has been obtained, both regarding the absolute values of the velocities and the mass transfer coefficients and the trends predicted by the theoretical analysis. In addition to providing further proof regarding the applicability of the mathematical modeling technique, the principal contribution of the work is that it provides an improved insight into the behavior of inductively stirred melts. In particular it was found that for an inductively stirred melt both the velocities and the rate of turbulence energy dissipation are relatively uniform spatially, in contrast to bubble stirred systems, where most of the agitation is confined to the jet plume and to the near surface region. It was found, furthermore, that the mass transfer coefficient characterizing the rate of dissolution of immersed carbon rods depends both on the absolute values of the melt velocity and on the local values of the turbulence intensity; thus significant mass transfer will occur in the region of the eye of the circulation, where the absolute value of the mean velocity is small.