Showing papers on "Mass transfer coefficient published in 1973"
578 citations
TL;DR: It was suggested that the diffusion coefficient of the cellular water may be the same as that of pure water, and that the observed reduction is simply due to this compartment, and the purpose of this study is to test these interpretations.
Abstract: In the conventional theories of biology, two major assumptions are usually granted implicitly, that is, that protoplasm is a dilute solution of salts and macromolecules, and that the membrane is the basic rate-limiting barrier. This classical view, however, is presently being challenged by a more fundamental theory called the association-induction hypothesis,’. Z! which proposes that the cell is a highly structured, complex entity and that the cellular transport mechanism is determined by the macromolecular interaction of ions and water. Some experiments have been reported in recent years to support this new alternative theory.’-‘ A significant portion of this evidence comes from the results of nuclear magnetic resonance (NMR) studies. For example, the spinspin relaxation time of muscle water proton was shown to be smaller than that of pure water by an order of magnitude, and this was interpreted by some investigators as evidence that the cellular water is “ordered.” 6* p, On the other hand, the self-diffusion coefficient of cellular water can be measured by the pulsed NMR method. I t is found to be almost one-half the value of the selfdiffusion coefficient of pure water.+’” Since the diffusion coefficient of ice is at least four orders of magnitude smaller than that of pure water, the relatively large diffusion coefficient of cellular water has been cited as evidence against the ordering of cellular water.” Furthermore, since it is known that a highly heterogeneous sample that includes small interior compartments can give a measured diffusion coefficient smaller than the actual value,’* it was suggested that the diffusion coefficient of the cellular water may be the same as that of pure water, and that the observed reduction is simply due to this compartment The purpose of this study is to try to test these interpretations.
69 citations
TL;DR: In this paper, the theory of gas absorption accompanied by fast pseudo-mth order reaction was used to obtain values of effective interfacial area in a packed column, irrigated with aqueous solutions and provided with 1 in.C. Raschig rings, 1 in in.P.V.
51 citations
01 Feb 1973
TL;DR: In this paper, the chemical and transport phenomena that may participate in controlling the oxidation rate of magnetite pellets were examined under a varying range of conditions including temperature, oxygen partial pressure, and porosity of the pellet.
Abstract: The chemical and transport phenomena that may participate in controlling the oxidation rate of magnetite pellets were examined. Reaction rates were measured under a varying range of conditions including temperature, oxygen partial pressure, and porosity of the pellet. Models based on the initial as well as developing reaction rates were used to explain the experimental findings. In contrast with many experimentally-made agglomerates, all pellet samples were made with a uniform internal structure. Such a condition was a prerequisite to obtaining a meaningful correlation of the experimental data with the theoretical base. A study of the initial reaction rates revealed that two mechanisms were operative in the first stages of pellet oxidation. Up to about 420°C a surface type of chemical reaction was the controlling step, while above 420°C mass transfer through the gaseous boundary layer was the controlling step and dominated the reaction rate. As the reaction developed within the pellet, mass transfer through the gaseous boundary layer as well as that through the product layer became the controlling steps. These mechanisms were studied in the temperature range of from 1000° to 1200°C and the role played by each was found to be a function of the amount of oxidation which had taken place.
48 citations
TL;DR: In this paper, mass transfer coefficients with gas and liquid phase controlling resistance using a concurrent flow packed column with a wide range of operating conditions and four types of packing were measured and correlated with dissipated energy values.
Abstract: Measurements were made of mass transfer coefficients with gas and liquid phase controlling resistance using a concurrent flow packed column with a wide range of operating conditions and 4 types of packing. Mass transfer coefficients were much larger than those obtainable in countercurrent towers. The results were correlated with dissipated energy values. The correlations obtained can be used to determine absorption efficiency. Experimental results show that the use of a high velocity concurrent flow column is particularly suitable when mass transfer is controlled by the liquid phase resistance with chemical reaction in the liquid. (18 refs.)
46 citations
TL;DR: In this article, the in-series resistances of the polyelectrolyte complex membrane and the polarized boundary layer of the sufactant rejected by the membrane were correlated to estimate the required membrane area and resultant ultrafiltrate concentration of surfactant to achieve any specified water recovery using cells-in-series and cellsin-parallel operation.
Abstract: Aqueous solutions 1.65 × 10−4 to 1.10 × 10−2 molar in the nonionic surfactant Triton X-100 are subjected to membrane ultrafiltration over the temperature range of 22 to 50°C in a continuous flow, thin channel cell, with channel Reynolds numbers from 50 to 1175. Data for the ultrafiltrate flux through the optimum polyelectrolyte complex membrane (of the three tested) are correlated by an equation involving the in-series resistances of the membrane and of the polarized boundary layer of the sufactant rejected by the membrane, with the latter resistance varied over a wide range. The correlations are used to estimate the required membrane area and resultant ultrafiltrate concentration of surfactant to achieve any specified water recovery using cells-in-series and cells-in-parallel operation. The gelation concentration and surfactant mass transfer coefficient are used to estimate water flux in the gel-polarization region.
43 citations
TL;DR: In this article, the effect of H 2 and O 2 evolution on the mass transfer coefficient of the reduction of K 3 Fe(CN) 6 and the oxidation of K 4 Fe(CP) 6 at nickel electrodes was studied up to 105 mA/cm 2.
38 citations
TL;DR: In this article, the effect of surface renewal on mass transfer is investigated for transfer to and from drops as well as across flat interfaces in stirred and laminar flow contactors.
Abstract: Surface-tension-induced interfacial convection (Marangoni phenomena) can appear as a result of mass and heat transfer, compression and dilatation of surface films or their non-Newtonian behaviour and owing to presence in the interface of electrostatic charges. In process engineering problems the mass transfer effect is usually predominant and, depending on the geometry of the system, leads to surface renewal or changes in interfacial area. The surface renewal phenomena can appear as instabilities or disturbances and their effect on mass transfer is presented for transfer to and from drops as well as across flat interfaces in stirred and laminar flow contactors. Mass transfer coefficients and drag coefficients of drops are compared under conditions of undisturbed (diffusional) transfer, cellular convection and interfacial turbulence for stable and unstable direction of transfer. The importance of gravitational instability is indicated.
34 citations
TL;DR: In this paper, the influence of molecular diffusion on liquid-liquid mass transfer in a stirred transfer cell has been found by measuring the rates transfer of helium and iso-butane from water to toluene and dekalin.
33 citations
TL;DR: In this article, a population balance model is considered for the description of mass transfer in liquid-liquid dispersions in a mechanically agitated vessel operated continuously, where the dispersions considered are of low dispersed phase fraction in which coalescence processes may be assumed to be negligible.
30 citations
TL;DR: In this paper, the effects of orientation, shape, and surface structure on the free convection mass transfer of plates, leaf and plant models were studied in an electrolytic system, and the results were extrapolated to the transfer of heat and mass in air, in an effort to predict realistic boundary-layer transfer coefficients for leaves and plant-like surfaces.
Abstract: Effects of orientation, shape, and surface structure on the free convection mass transfer of plates, leaf- and plant-models were studied in an electrolytic system. The results were extrapolated to the transfer of heat and mass in air, in an effort to predict realistic boundary-layer transfer coefficients for leaves and plant-like surfaces. Flow visualization complemented the investigation.
TL;DR: In this article, the rates of electrochemical mass transfer by free convection under the influence of simultaneous thermal free convections have been measured for upward facing horizontal disc electrodes, where the electrode reaction was the cathodic deposition of copper from cupric sulphate solutions containing H 2 SO 4 as swamping electrolyte.
TL;DR: In this article, the mass transfer coefficient during the absorption of CO2 from bubbles rising in water gave similar values to those obtained during the desorption of CO 2 from saturated solutions into inert bubbles which had been formed under mercury to prevent premature transfer.
TL;DR: The mass transfer characteristics of packed bubble columns were studied by employing various packings of different sizes and shapes in 10-38·5 cm id columns as discussed by the authors, and the theory of absorption accompanied by pseudo-mth order reaction was used to obtain the values of effective interfacial area.
TL;DR: In this paper, the authors investigated the effect of varying impeller dimensions and operating speed on the volumetric mass transfer in a simulated fermentation medium, made up of 16 kg of paper pulp per m 3 of aqueous sodium sulphite solution with a cupric ion catalyst.
TL;DR: The liquid phase mass transfer coefficient kL for the absorption of oxygen in tap water and in ionic solutions has been calculated from the quotien======\/\/\/\/\/\/\/\/\/\/\/19]\/\/\/\/21]\/\/19'
TL;DR: In this article, the authors examined the logarithm of the rate constants of polycyclic aromatic hydrocarbons measured by electron spin resonance, pulse radiolysis and quenching of fluorescence methods.
TL;DR: In this paper, a theoretical extension of a mathematical model (after Ames) is described, which incorporates both mass transfer-limitations between biomass and liquid film, and kinetic biological reaction rate of organic "food" utilization.
TL;DR: In this paper, a mixture of two immiscible liquids in co-current turbulent flow without phase change was extensively studied, and a good correlation was obtained for the heat transfer coefficient expressing the Nusselt number in terms of the Peclet number.
TL;DR: In this paper, the two-compartment diffusion cell reported by Stokes was modified for operation at temperatures higher than the ambient temperature, and diffusion coefficients at normal boiling points of these mixtures were obtained by extrapolation and interpolation.
Abstract: The two-compartment diffusion cell reported by Stokes was modified for operation at temperatures higher than the ambient temperature. Experimental diffusion coefficients were obtained for concentrations of 0.05, 0.25, 0.50, 0.70, and 0.96 mole fraction of benzene in nheptane at 25", 45", 65", 75', and 85°C. Diffusion coefficients at normal boiling points of these mixtures were obtained by extrapolation and interpolation. Also, the diffusion coefficients at infinite dilution for benzene and n-heptane were obtained by extrapolation at all the temperatures of the experiment.
TL;DR: In this article, a new theoretical treatment of the growth of a fast moving spherical second phase as governed by simultaneous heat and mass transfer limitations is presented, and the solution to these complex coupled cases can be related to the available uncoupled cases.
TL;DR: In this article, the problem of simultaneous heat and mass transfer associated with the vacuum distillation of a thin liquid film is solved by analyzing the system as a conjugated boundary value problem.
TL;DR: In this paper, the similarity transformation suggested by Ruckenstein is applied to find the mass transfer in the absence of chemical reactions from a single component fluid sphere and the same transformation is combined with Duhamel's theorem in order to obtain the solution.
TL;DR: In this paper, the authors measured the local mass transfer coefficient in turbulent duct flow using a new experimental technique and found that the experimental results agreed quite well with a numerical solution to the turbulent diffusion equation in channel flow.
01 May 1973
TL;DR: In this paper, the influence of gas phase resistance will de-pend on the concentration of the transferred species in both the gas and the liquid as well as on the mass transfer coefficients in both gas and liquid phases.
Abstract: When a dilute gas is absorbed in a liquid metal in which Sievert’s law is obeyed, the gas phase resistance is likely to be significant. The influence of gas phase resistance will de-pend on the concentration of the transferred species in both the gas and the liquid as well as on the mass transfer coefficients in both the gas and liquid phases. An overall mass transfer coefficient is defined by: n″(X)1=kov√pb -cb and equations are developed relating this to the variables mentioned. Experimental work has been carried out with dilute oxygen jets (p(O2) = 0.1 and 0.2 atm) blowing onto molten silver, and the results have confirmed that the resistance in the gas phase contributes to the overall resistance. From these results it has been possible to estimate gas phase mass transfer coefficients which range from 1.4 cm/s for a jet momentum of 8000 dyne and lance height of 18.5 cm to 4.8 cm/s for a jet momentum of 56,000 dynes and lance height of 10.5 cm.
TL;DR: In this article, the authors measured the rate of fluid exchange between the attached recirculating wake and the free stream for spheres and circular discs set normal to the flow in terms of mass transfer coefficient, the height of a transfer unit and dimensionless mean residence time.
01 Aug 1973
TL;DR: In this paper, a method for determining the heat transfer coefficient from temperature measurements at internal points in bodies of the simplest geometry is proposed, which can be used for determining heat transfer coefficients.
Abstract: A method is proposed for determining the heat transfer coefficient from temperature measurements at internal points in bodies of the simplest geometry.