Showing papers on "Mass transfer coefficient published in 1980"
TL;DR: In this article, a procedure for the prediction of wall-bed heat transfer coefficient for bubble columns and gas-solid fluidized beds is developed on the basis of hydrodynamic behavior of these contactors.
Abstract: A procedure for the prediction of wall-bed heat transfer coefficient for bubble columns and gas-solid fluidized beds is developed on the basis of hydrodynamic behavior of these contactors. A comparison between the predicted and experimental values of heat transfer coefficient over a wide range of design and operating variables is presented. An attempt is made to analyze the occurrence of maxima in heat transfer coefficient with respect to gas velocity in the case of fluidized beds. A procedure for the calculation of the optimum superficial gas velocity is outlined.
60 citations
TL;DR: In this paper, an adsorption mass transfer model is applied to describe virus association with soils and soil components, and the model has general applicability to the description of virus movement through soil when K L, Q and k f are known for specific virus-soil combinations.
53 citations
TL;DR: In this article, the absorption rates of NO and NO 2 mixtures were determined by simultaneously measuring the gas and liquid phase compositions, and the parameters required for predicting the absorption, including the solubilities of NO 2 and N 2 O 4, the hydration rates of n 2 O 3 and n 2 o 4 and the equilibrium constants, have been established.
51 citations
TL;DR: In this paper, the problem of mass transfer coupled with an irreversible chemical reaction of the first order in plug flow, Couette flow, in Couette Flow with a moving interface, and in fully developed boundary layer flow is investigated.
47 citations
TL;DR: In this paper, a simple model is assumed for the growth of crystals from solution, based on an assumption that the crystal growth depends mainly on two consecutive steps, i.e. diffusion and surface reaction.
45 citations
TL;DR: In this article, the authors measured the volumetric liquid-phase mass transfer coefficient, the interfacial area and the true liquid phase transfer coefficient (kL) in three-phase fluidized beds.
Abstract: The technique of simultaneous measurement of the mass transfer coefficient and the interfacial area (Robinson and Wilke, 1974) was used to measure the volumetric liquid-phase mass transfer coefficient , the interfacial area and the true liquid-phase mass transfer coefficient (kL) in three-phase fluidized beds. The eddy-cell model of Lamont and Scott (1970) was found to give a reasonable fit to the kL data, if the proportionality constant is modified. The and data were correlated by empirical equations. Some information on bubble diameter was deduced from the interfacial area and holdup measurements.
39 citations
36 citations
TL;DR: In this article, an analysis is made of mass transfer into a laminar finite falling film with accompanying heat transfer and interfacial shear, and the analysis is extended to include chemical reaction with linear reaction kinetics.
30 citations
TL;DR: In this article, a theoretical study dealing with the impregnation of one or two active species on a porous support, in order to predict the internal concentration as a function of the process parameters, is presented.
26 citations
TL;DR: In this paper, the mass transfer enhancement and pressure drop properties of an electrolytic parallel plate cell with a cloth separator in contact with the electrodes have been studied and a surface renewal model of turbulent mass transfer has been used.
26 citations
TL;DR: In this article, a generalized treatment of heat and/or mass transport between an assemblage of particles and a surrounding continuum is presented, where the conditions for which particles can be treated as isolated or as interactive members of a group are established, and correction factors are presented from which multiple particle mass transfer rates can be calculated from single isolated particle transfer rates.
Abstract: A generalized treatment of heat and/or mass transport between an assemblage of particles and a surrounding continuum is presented. The unsteady state diffusive transport is shown to depend on the size and positions of the particles, and the rate processes are found to be radically different from single particle rates because of particle interactions. A three dimensional model has been developed to predict global concentration or temperature distributions by treating the particles as point sources or sinks. The conditions for which particles can be treated as isolated or as interactive members of a group are established, and correction factors are presented from which multiple particle mass transfer rates can be calculated from single isolated particle mass transfer rates. For finite assemblages the correction factors are shown to be in close agreement with results computed previously using the method of images.
TL;DR: In this article, non-dimensional correlations allowing for calculation and scale up of the gas holdup, liquid-side mass transfer coefficient and mechanical power in gas liquid stirred tanks when such parameters as superficial gas velocity and stirring speed are given.
TL;DR: In this paper, the Laplace equation was applied to the problem of calculating the transfer rates of interacting spherical particles, which differ in size and chemical composition, and the effect of interactions on these transfer rates may be either positive (enhance transfer) or negative (retard transfer).
TL;DR: In this article, the performance of cellulose acetate membranes in terms of pure water permeability constant, solute transport parameter, and mass transfer coefficient with a reference system of aqueous sodium chloride solution was characterized.
Abstract: Cellulose acetate membranes were characterized in terms of pure water permeability constant, solute transport parameter, and mass transfer coefficient with a reference system of aqueous sodium chloride solution. Reverse osmosis separation behavior of sulfate, thiosulfate, dithionate, trithionate, and tetra-thionate was studied. Plant effluents containing various thiosalts and metal ions were subjected to reverse osmosis at 300 psig, and product water of suitable quality for use in recycle operations was obtained.
TL;DR: In this paper, a theoretical analysis of the transport phenomena that occur in the laminar-flow region in a tube divided into two half-cylindrical channels, showed that the mass transfer coefficient increased by a factor 1.95 as compared with the Mass Transfer coefficient in a cylindrical tube.
TL;DR: In this article, an empirical and semi-theoretical derivation of the correlations between the j M factor and the modified Reynolds number Re' for mass transfer between a wall or an immersed surface and a flowing liquid in fixed beds is proposed.
01 Mar 1980
TL;DR: In this article, the authors apply the film theory by Ackermann to simultaneous heat and mass transfer processes, if the mass flux normal to the wall is induced by diffusion, which is not fulfilled when condensing vapor mixtures.
Abstract: The film theory by Ackermann can be applied to simultaneous heat and mass transfer processes, if the mass flux normal to the wall is induced by diffusion. Since this condition mostly is not fulfilled when condensing vapor mixtures, an approximative procedure is developed taking into account the influence of suction in condensation heat transfer. The accuracy of the method turns out to be satisfactory compared with results obtained by numerical analysis.
TL;DR: In this paper, the exact solution of the Maxwell-Stefan equations for multicomponent mass transfer based on a film model is compared with the solution of linearised equations, and it is first shown that the formu...
Abstract: The exact solution of the Maxwell-Stefan equations for multicomponent mass transfer based on a film model is compared with the solution of the linearised equations. It is first shown that the formu...
TL;DR: The computational algorithm for calculating rates of mass transfer in multicomponent mixtures using the film model proposed by Krishna and Standart can be unstable for certain physical processes as discussed by the authors, and successful prediction of the molar fluxes can usually be achieved by evaluating the diffusive fluxes at the appropriate position on the diffusion path.
Abstract: The computational algorithm for calculating rates of mass transfer in multicomponent mixtures using the film model proposed by Krishna and Standart can be unstable for certain physical processes. Successful prediction of the molar fluxes can usually be achieved by evaluating the diffusive fluxes at the appropriate position on the diffusion path.
TL;DR: In this article, the mass transfer coefficient was measured for the deposition of copper from acidified copper sulphate solution at a vertical cylinder cathode stirred by oxygen evolved at a horizontal lead anode placed below the cylinder.
Abstract: Mass transfer coefficients were measured for the deposition of copper from acidified copper sulphate solution at a vertical cylinder cathode stirred by oxygen evolved at a horizontal lead anode placed below the cylinder. Variables studied were: oxygen discharge rate, electrolyte concentration and cylinder height. The mass transfer coefficient was found to increase by a factor of 1.8–2.6 depending on oxygen discharge rate and cylinder height. The mass transfer coefficient was related to oxygen discharge rate and cylinder height by the equation:
$$K = 65.8 \times 10^{ - 4} \frac{{V^{0.358} }}{{h^{0.29} }}$$
TL;DR: In this paper, a modified Prandtl analogy is applied, by considering the eddy penetration of the diffusion sublayer, to obtain the following expression for forced convection mass transfer Sh Sc− 1 3 = 0.62fRe which is found to correlate the present and previous data in the range of Sc, 2.6-32000, Pr, 0.72-676 and Re, 102-105 with a standard deviation of 14.6%.
TL;DR: In this paper, a simple method is suggested for the modelling of hydrodynamics of reacting gas-liquid systems in large-scale bubble column reactors, where values of liquid-side mass transfer coefficient (kL), interfacial area (a), and gas holdup ratio (e) can be predicted on the basis of experimental gas hold-up data obtained for the reacting system and for an appropriate standard (reference) system in a laboratory scale bubble reactor.
TL;DR: In this article, the first moment of the response curve was used to obtain the adsorption equilibrium constant K for benzene on activated carbon particles at 298°K and 1 atm.
Abstract: Experimental breakthrough curves were determined for a liquid full and a trickle bed reactor in which benzene was adsorbed from water on small activated carbon particles at 298°K and 1 atm. The step function of benzene was introduced into the water feed and the response measured in the liquid effluent. Benzene transfer also occurred from the liquid feed to the gaseous feed of pure helium.
Moment analysis of data for liquid full conditions indicated that the first moment of the response curve could be used to obtain the adsorption equilibrium constant K for benzene on activated carbon. Comparison of results obtained by this new method with the K value determined from static equilibrium runs demonstrated the validity of the moment theory.
Analysis of the response curves for trickle bed operation showed that the liquid-to-gas mass transfer coefficient (ka)L could be evaluated from either the zero or first moment. Results were obtained in both the trickling flow and pulse flow regimes. Values of (ka)L in the pulse flow regime, which were not heretofore available were sharply higher than those for trickle flow.
TL;DR: The coefficient of mass transfer decreases during carburizing with increasing surface concentrations of carbon in the steel due to the effect of the adsorbed carbon on the rate of the reaction as mentioned in this paper.
Abstract: 1.
The coefficient of mass transfer decreases during carburizing with increasing surface concentrations of carbon in the steel due to the effect of the adsorbed carbon on the rate of the reaction.
2.
With rising temperatures the variation of the mass transfer coefficient with the surface concentration of carbon increases.
TL;DR: In this article, the mass transfer of acetic and propionic acid from toluene droplets and acetone from n-butyl acetate droplets into the continuous water phase was measured with a time resolution of 10 msec by a modified liquid scintillation technique.
Abstract: Single droplets were formed at the tip of different capillaries employing high droplet formation rates and continuous phase flow rates. The mass transfer of acetic and / or propionic acid from toluene droplets and acetone from n-butyl acetate droplets into the continuous water phase was measured during droplet formation with a time resolution of 10 msec by a modified liquid scintillation technique. The solute concentration, as a function of time, passes an inflexion point during the first 0.5 sees. By employing the mass balance and the developing droplet geometry the instantaneous mass transfer coefficient was determined, which passes a maximum at the inflexion point of the concentration vs. time curve. The influence of the location of the partition coefficient, the droplet Reynolds number and the continuous phase Reynolds number on the instantaneous mass transfer coefficient was investigated. Serious deficiencies of published models are discussed.
TL;DR: In this article, a double resistance model was proposed for assessing the relative resistances afforded by the corrosion product layer and the liquid film or damped turbulence layer, and it was found that the mass transfer coefficient in the damped turbulent layer controlled the overall mass transfer process for the exposure time, flow rates, and sulphate ion concentration ranges examined.
TL;DR: In this paper, the authors show that the superposition of the corona wind on the flow field near the catalytic surface may augment overall reaction rates by increased mixing, which may limit the effects of diffusion and increase catalyst effectiveness.
Abstract: Since Senftleben1 first indicated that in the presence of electric fields, heat transfer rates may be increased substantially beyond natural convection values, correlations have been proposed relating electric field and fluid flow parameters to film coefficients of transfer. The ‘corona wind’, which exists in a non-uniform electric field before spark breakdown, can be used to alter the hydrodynamics of convective diffusion processes such that an augmentation of transport rates in wall boundary layers can be achieved2–6. Corona wind augmentation of wall reactions, particularly catalytic combustion processes, has not previously been considered7,8, but as catalytic combustion is a convective diffusion process, the superposition of the corona wind on the flow field near the catalytic surface may augment overall reaction rates by increased mixing. For very rapid surface reactions, where molecular diffusion inhibits the overall rate and lowers overall rate constants, corona wind augmentation may limit the effects of diffusion and, thereby, increase catalyst effectiveness. Improvements in the overall rate constant, or mass transfer coefficient, would be useful in many areas, including air pollution control, energy conservation, and the design of compact, controlled heat flux catalytic combustors. We report here our test of the catalytic combustion of hydrogen at one atmosphere on platinised alumina in a flow reactor with a uniformly accessible catalyst surface. By this experimental design we may be able to obtain reaction rate data from the kinetically controlled to the diffusion limited regimes of combustion owing to the high activity of hydrogen on metallic platinum. A uniformly accessible catalyst surface also permits analysis of the reaction rate data using either one- or two-dimensional approaches.