Showing papers on "Mass transfer coefficient published in 1987"
TL;DR: In this article, a critical review on the mass transfer correlations under turbulent duct flow, as they appeared in the literature ( 1934-1984), and a discussion on the factors influencing mass transfer during membrane operations (reverse osmosis and ultrafiltration), like porosity and roughness of the membrane wall and change of viscosity and diffusion coefficient due to the strong concentration gradient.
358 citations
TL;DR: In this article, the authors compared the performance of different dynamic methods for the volumetric mass transfer coefficient for oxygen kla obtained by various dynamic methods and concluded that only one variant gives correct results over a wide range of power dissipated per unit volume.
220 citations
TL;DR: In this paper, reversible entropy generation for combined forced convection heat and mass transfer in a two-dimensional channel is investigated, and the authors obtain the entropy as a function of velocity, temperature, concentration gradients and the physical properties of the fluid.
82 citations
01 Jun 1987-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the authors measured the mass transfer between two immiscible liquids, oil and water simulating slag and steel, respectively, in a scale model of a ladle and found that the mixing times in the presence of the oil layer and mass transfer coefficient for the dissolution of solid benzoic acid rods were measured.
Abstract: Several of the metallurgical reactions occurring in gas stirred steel ladles are controlled by liquid phase mass transfer between the metal and slag. In order to calculate the rate of these reactions, information about the two phase mass transfer parameter is necessary. The mass transfer between two immiscible liquids, oil and water simulating slag and steel, respectively, was measured in a scale model of a ladle. The mass transferred species was thymol which has an equilibrium partition ratio between oil and water similar to that for sulfur between slag and metal. The mass transfer rate was measured as a function of gas flow rate, tuyere position and size, method of injection, oil viscosity, and oil/water volume ratio. In addition, mixing times in the presence of the oil layer and mass transfer coefficient for the dissolution of solid benzoic acid rods were measured. The results show that there are three gas flow rate regimes in which the dependence of mass transfer on gas flow rate is different. At a critical gas flow rate, the oil layer breaks into droplets which are entrained into the water, resulting in an increase in the two phase interfacial area. This critical gas flow rate was found to be a function of tuyere position, oil volume, densities of two phases, and interfacial tension. Two phase mass transfer for a lance and a tuyere was found to be the same for the same stirring energy in low energy regions regardless of lance depth. Mass transfer is faster for a center tuyere as compared to an offcenter tuyere, but mixing times are smaller for the offcenter tuyere. From the results obtained, the optimum stirring conditions for metallurgical reactions are qualitatively discussed.
81 citations
TL;DR: In this paper, the mass transfer and hydrodynamic characteristics of a loop reactor were investigated using downflow liquid jet ejectors fitted with straight-and venturi-type throats, and the entrainment rate of the liquid jet and the gas holdup were shown as functions of power input per unit volume of liquid.
79 citations
TL;DR: In this article, the applicability and limitations of such a model for a number of membrane-solute-solvent systems were studied and the boundary layer and membrane resistances to solute transport were isolated and simple relations developed for the overall mass transfer coefficient in such systems.
Abstract: Dispersion-free solvent extraction using microporous hydrophobic membranes has been extended to hydrophilic and composite hydrophobic-hydrophilic membranes. Excess phase pressure conditions, if needed for dispersion-free operation, have been identified. Boundary layer and membrane resistances to solute transport have been isolated and simple relations developed for the overall mass transfer coefficient in such systems. A variety of flat microporous membranes have been utilized. Previous investigations by others had interpreted the membrane mass transfer resistance using the notion of unhindered diffusion through tortuous pores of the membrane. We have studied here the applicability and limitations of such a model for a number of membrane-solute-solvent systems.
76 citations
TL;DR: In this article, a colonne a bulles de 0,10 m de diametre and 2,50 m de hauteur, avec le systeme air-eau et divers alcools, was presented.
Abstract: Resultats experimentaux obtenus dans une colonne a bulles de 0,10 m de diametre et 2,50 m de hauteur, avec le systeme air-eau et divers alcools
74 citations
TL;DR: This paper showed that liquid-liquid extractions with microporous membranes will be more rapid when the membrane is wetted by the phase having the higher solubility for the solute being transferred.
72 citations
TL;DR: In this article, the authors present experimental results on diffusional mass transfer between a liquid and flow-through porous electrodes made of disks of nickel felt or foam, and compare the performances of different stacks of disks.
57 citations
TL;DR: In this paper, a correlation of the maximum turbulent heat or mass transfer coefficient in the reattachment region of separated flow is proposed based on surveying thoroughly previous data and also on conducting heat transfer measurements.
49 citations
TL;DR: In this paper, mass transfer coefficients on the surface of a porous glass membrane were obtained from separation tests of H2-CO mixtures, and these data agree with the correlation presented by Ghosh and Upadhyay for mass transfer on an impermeable wall.
Abstract: Mass transfer coefficients on the surface of porous glass membrane were obtained from separation tests of H2-CO mixtures. These data agree with the correlation presented by Ghosh and Upadhyay for mass transfer on an impermeable wall. In addition, effects of the selectivity of membrane and bulk composition on the concentration polarization phenomenon are discussed and the limiting permeability which is affected by the polarization is represented as a function of mass transfer coefficient.
TL;DR: In this paper, an equation describing the permeation rate of zinc transport through a supported liquid membrane containing di(2-ethylhexyl)phosphoric acid (D2EHPA) as a mobile carrier has been derived, taking into account aqueous film diffusion, interfacial chemical reaction, and membrane diffusion as simultaneous controlling factors.
TL;DR: In this article, a dynamic response method was used to measure the volumetric mass transfer coefficient for oxygen in a mechanically agitated vessel containing an aqueous suspension of 66 μm glass beads.
Abstract: A dynamic response method was used to measure the volumetric mass transfer coefficient for oxygen in a mechanically agitated vessel containing an aqueous suspension of 66 μm glass beads. At constant stirring speed and superficial gas velocity the volumetric gas transfer coefficient kLa was found to decrease with solids loading. A generalized equation correlated the results in terms of the volume concentration of the solids, the total power input per slurry volume, and the superficial gas velocity.
TL;DR: In this article, the solubilities in compressed C02 of the lipid components in freshly ground rape seed and of glycerol trioleate (a typical constituent of rape oil) at pressures up to 200 bar and temperatures 25 to 75C were given.
Abstract: Equilibrium data are given for the solubilities in compressed C02 of the lipid components in freshly ground rape seed and of glycerol trioleate (a typical constituent of rape oil) at pressures up to 200 bar and temperatures 25 to 75C. Continuous flow tests in which a bed of ground rape seed was contacted with a stream of liquid CO2 at 25C and varied flow conditions are also reported. The results are collated in terms of an empirical mass transfer coefficient. A sharp change took place in the lipid concentration in the extractant stream leaving the bed when about 65% of the available oil had been extracted. This, and changes in the composition of the extract, are discussed, together with the use of this type of data for design purposes.
TL;DR: In this article, the mechanism and rate limitations in aqueous nitrogen oxides absorption are reviewed and data available on chemical kinetics for performance predictions are discussed and application of a rate relationship to characterize interphase mass transfer for the primary reactant N2O4 is shown, with mass transfer coefficients derived from plant-scale data.
Abstract: The mechanism and rate limitations in aqueous nitrogen oxides absorption are reviewed and data available on chemical kinetics for performance predictions are discussed. Application of a rate relationship to characterize interphase mass transfer for the primary reactant N2O4 is shown, with mass transfer coefficients derived from plant-scale data. Correlations for these coefficients as functions of acid strength and temperature for both bubble cap and sieve plate designs are presented.
TL;DR: In this paper, the authors measured the film surface temperature with an infrared pyrometer and determined the heat and mass transfer coefficients independently of each other by measuring the surface temperature of the film.
Abstract: In non-isothermal absorption of steam in falling films of aqueous LiBr solutions local heat and mass transfer coefficients were determined independently of each other by measuring the film surface temperature with an infrared pyrometer. The experimentally determined mass transfer coefficients (Sherwood numbers) confirm well-known correlations, as well as the statements of the Levich-type description of falling film heat and mass transfer, that is, the damping of the turbulence not only near the wall but also in the vicinity of the film surface. So, the assumption that the bulk and the surface temperatures of the film are equal, owing to undamped eddy transport, is not correct. The experimentally determined heat transfer coefficients deviate from the experimental data of Blangetti, the latter determined in film condensation of 1-methoxy-2-propanol-water azeotrope (MWA). This discrepancy is due to the thermal entrance effects in the experiments of Blangetti and will be discussed in Part II.
TL;DR: In this article, carbon dioxide was absorbed from gas mixtures of CO/sub 2/CO/sub 3/ into 0.5 M Na/sub 1/CO 3/CO 4/CO 5/CO 6/CO 7/CO 8/CO 9/CO 10/CO 11/CO 12/CO 13/CO 14/CO 15/CO 16/CO 17/CO 18/CO 19/CO 20/CO 21/CO 22/CO 23/CO 24/CO 25/CO 26/CO 28/CO 29/CO 30/HCO
Abstract: In catalytic slurry reactors, fine catalyst particles are suspended either by mechanical stirring or by passage of a gas. In the former, although the gas is normally sparged, in some applications a gentle stirring may be preferred. In this case, the surface renewal rates are low, resulting in low physical mass transfer coefficients. Under these circumstances, particles with high adsorbing capacity, such as activated carbon, may circulate between the diffusion layer adjacent to the interface where adsorption takes place, and the bulk where desorption occurs. Such a ''shuttle'' mechanism results in increased physical mass transfer rates. In this work, carbon dioxide was absorbed from gas mixtures of CO/sub 2//N/sub 2/ into 0.5 M Na/sub 2/CO/sub 3//0.5 M NaHCO/sub 3/ solutions containing various amounts of arsenite, in the absence and presence of finely powered activated carbon. Some additional experiments were also carried out using fine kieselguhr particles, which were not porous.
TL;DR: In this paper, a mass transfer model based on external film mass transfer, macropore diffusion and micropores diffusion was developed to explain the adsorption of pollutants from aqueous solutions onto adsorbent particles.
TL;DR: The application of this approach provides a method for determining axial dissolved oxygen profiles under conditions of known mass transfer rates as a function of agitation–aeration characteristics and can serve as a basis for testing single turbine correlations and adapting them to multiturbine systems.
Abstract: A methodology for mathematically analyzing agitator performance and mass transfer in large multiturbine production fermentors is presented. The application of this approach provides a method for determining axial dissolved oxygen profiles under conditions of known mass transfer rates as a function of agitation-aeration characteristics. A stagewise approach is used which divides the fermentor into a series of mixing cells. This allows for each turbine and mixing cell to be individually optimized. The model also permits the determination of the mass transfer coefficient for each turbine based upon limited dissolved oxygen data. The primary limitation of this approach rests in the limited data and correlations available for multiturbine systems. The structure of the modelling approach can serve as a basis for testing single turbine correlations and adapting them to multiturbine systems. The step-by-step details of the mathematical analysis are presented and interpreted. A series of computer simulations demonstrate the effect of typical fermentor operating variables on the axial dissolved oxygen profile. Further simulations demonstrate the effect of modifying agitator blade numbers on the dissolved oxygen profile and agitator power requirement.
TL;DR: In this article, a mathematical model for mass transfer at gas-evolving electrodes with superimposed electrolyte flow through the interelectrode gap is developed and discussed, and the resulting equation for the combined mass transfer coefficient takes account of the individual mass transfer coefficients.
TL;DR: In this article, the performance characteristics of a packed-bed biological reactor have been analyzed taking into consideration the diffusional resistance of the biofilm, and the model equations are solved by the method of orthogonal collocation from the transient to the steady state condition for various reaction kinetics.
TL;DR: In this article, the influence of suspended particles upon such parameters as gas holdup, volumetric liquid-state mass transfer coefficient, and gas-liquid interfacial area in a bubble column were investigated in sodium sulfite/sulfate solutions in which various loadings of coarse nylon particles and fine alumina particles were suspended.
Abstract: Influences of suspended particles upon such parameters as gas holdup, volumetric liquid-state mass-transfer coefficient, and gas-liquid interfacial area in a bubble column were investigated in sodium sulfite/sulfate solutions in which various loadings of coarse nylon particles and fine alumina particles were suspended. The volumetric mass-transfer coefficients and gas holdups were a bit increased by suspending a small amount of fine particles. The gas-liquid interfacial area in a slurry bubble column in which a small amount of fine particles were suspended was found to be higher than that in a two-phase bubble column.
TL;DR: A partir de resultats experimentaux d'une precedente etude concernant le coefficient de transfert de matiere volumetrique evaluation separee du coefficient of transfert of matiere and de l'aire interfaciale specifique as discussed by the authors.
Abstract: A partir de resultats experimentaux d'une precedente etude concernant le coefficient de transfert de matiere volumetrique evaluation separee du coefficient de transfert de matiere et de l'aire interfaciale specifique
TL;DR: In this paper, the mass transfer of ozone absorbed by water in a semi-comtinuous stirred reactor is studied at the lab scale, and a complete factorial scheme is used to investigate the effect of agitation speed and gas flow.
Abstract: Mass Transfer of ozone absorbed by water in a semi-comtinuous stirred reactor is studied at the lab scale. Experimental investigation using a complete factorial scheme shows a predominant effect of agitation speed and gas flow and results in a correlation for the mass transfer coefficient, k1a. Solubility of ozone in water is estimated by evaluation of an apparent Henry's law constant for different temperatures (20* and 50*C), pH values (2 and 7) and a t constant ionic strength (0.13).
TL;DR: In this paper, mass transfer to wall electrodes was investigated in a circular cell agitated by gas bubbles, where perforated and porous plates were used as gas spargers and the enhancing effect of gas bubbles on the mass transfer coefficient was found to be a function of the gas hold-up.
Abstract: Mass transfer to wall electrodes was investigated in a circular cell agitated by gas bubbles. Perforated and porous plates were used as gas spargers. Electrodes with varying height and electrolytic solutions having different physical properties were tested. It was found that the enhancing effect of gas bubbles on the mass transfer coefficient is a function of the gas hold-up, irrespective of the velocity of the gas flow and the gas distributor employed.
01 Jan 1987-Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering
TL;DR: In this article, anodic oxidation of C.I. direct blue was carried out in an electrochemical reactor at a constant temperature of 20°C. The technique was found successful in removing the color of the dye from aqueous solutions containing 0.5 M sodium sulfate.
Abstract: In this work, anodic oxidation of C.I. direct blue 21 was carried out in an electrochemical reactor at a constant temperature of 20°C. The technique was found successful in removing the color of the dye from aqueous solutions containing 0.5 M sodium sulfate. Variables studied were: initial dye concentration, solution flow rate to the reactor, anode area, current density and time duration of anodic oxidation. It was found that the rate of dye removal increased with increasing current density, duration of anodic oxidation and solution flow rate. The mass transfer coefficient was found to increase with increasing reactor current density, decreasing the area of the anode and decreasing the initial dye concentration.
TL;DR: In this paper, mass transfer rates were measured for the cathodic reduction of potassium ferricyanide at a H2-evolving electrode consisting of a packed bed of spheres.
Abstract: Mass transfer rates were measured for the cathodic reduction of potassium ferricyanide at a H2-evolving electrode consisting of a packed bed of spheres. Variables studied were bed height, H2 discharge rate and ferricyanide concentration. It was found that the mass transfer coefficient (K) is related to the H2 discharge rate (V) by the equation
$$K = aV^{0.325} $$
Bed height and electrolyte concentration were found to have little effect on the mass transfer coefficient. A mathematical model based on the surface renewal theory was formulated to explain the mechanisms of mass transfer at gas-evolving electrodes.
TL;DR: In this article, a modified hydrodynamic model, where a laminar solution flow is induced by rising bubbles, has been proposed in order to calculate the mass transfer coefficient of indicator ions on the length of a gas-evolving electrode.
Abstract: Various models have been proposed to describe the mass transfer of indicator ions to gas-evolving electrodes. For verification of the proposed models, the dependence of the mass transfer coefficient of indicator ions,kj, on the length,Le, of a gas-evolving electrode may be very useful. Experimental relations betweenkj andLe have been determined for oxygen-evolving as well as hydrogen-evolving vertical electrodes in a supporting electrolyte of 1 M KOH. Moreover, a modified hydrodynamic model, where a laminar solution flow is induced by rising bubbles, has been proposed in order to calculatekj. It has been found that this model is not useful for both types of gas-evolving electrodes. The experimental results support the earlier proposed convection-penetration model for the oxygen-evolving electrode. The solution flow near a vertical electrode, induced by rising bubbles, behaves in a turbulent manner.