Showing papers on "Mass transfer published in 1980"
TL;DR: In this article, the authors derived theoretically an equation for the heat transfer in bubble agitated systems by combining the surface renewal model of mass transfer with Kolmogoroff's theory of isotropic turbulence.
265 citations
TL;DR: In this paper, over 1000 sets of data for forced convective boiling of distilled water, distilled glycol and aqueous mixtures of ethylene glycol are reported, showing that a significant reduction in the heat transfer coefficient is observed for mixtures attributable to mass transfer effects.
Abstract: Over 1000 sets of data for forced convective boiling of distilled water, ethylene glycol and aqueous mixtures of ethylene glycol are reported. Most of these data were taken in the annular flow regime. These data indicate a previously unrecognized Prandtl number effect on the boiling heat transfer for both pure components and mixtures. A significant reduction in the heat transfer coefficient is observed for mixtures attributable to mass transfer effects. An expression is developed which accounts for both of these effects and correlates the experimental data to within a mean deviation of 14.9%. This correlation reduces to the standard Chen correlation for pure fluids with Prandtl numbers close to unity.
216 citations
TL;DR: In this article, a numerical simulation of a laboratory experiment involving coupled heat and mass transfer in a horizontal porous medium column with one end subjected to a temperature below 0°C has been carried out.
Abstract: A numerical simulation of a laboratory experiment involving coupled heat and mass transfer in a horizontal porous medium column with one end subjected to a temperature below 0°C has been carried out. The model is essentially that of Harlan (1973) and is solved numerically by the finite difference method using the Crank-Nicholson scheme. The solution yields temperature, liquid water content, and ice content profiles along the column as a function of time. Comparison of the experimental results and the simulation analysis results shows that Harlan's model, with some modification in the hydraulic conductivity of the frozen medium, can be used successfully to simulate numerically the coupled heat and mass transfer processes when ice lensing does not occur.
209 citations
TL;DR: In this paper, a random pore model is used to relate pore surface area, pore volume and effective diffusivity to the local burnoff, and the equations for oxygen concentration and burnoff as functions of time and position are solved analytically for the limiting case of strong diffusional limitations (high temperature or particle size).
Abstract: The combustion of char particles including the effects of external mass transfer, surface reaction, pore diffusion, and pore growth is analyzed theoretically. A random pore model is used to relate pore surface area, pore volume and effective diffusivity to the local burnoff. The equations for oxygen concentration and burnoff as functions of time and position are solved analytically for the limiting case of strong diffusional limitations (high temperature or particle size) and numerically for the general case. The results include the variation of particle size and density with burnoff under conditions pertinent to pulverized and fluidized combustion. The analysis is compared with previous analyses from the literature.
125 citations
TL;DR: In this paper, a physical model is presented to explain the dramatic interfacial tension minima that may sometimes occur during the equilibration of a surface-active solute between two liquid phases.
96 citations
TL;DR: In this paper, the finite element method is used to analyse heat and mass transfer problems in porous media, in which the thermophysical properties are allowed to vary as functions of temperature and moisture.
Abstract: The finite element method is used to analyse heat and mass transfer problems in porous media, in which the thermophysical properties are allowed to vary as functions of temperature and moisture. An example is given of the application of the method to the problem of timber drying.
96 citations
TL;DR: In this paper, a ternary diffusion and viscous flow model was used to predict the concentration profiles for gases and tar in coal pyrolysis, showing that at low pressures, product yields depend on particle size only, while at high pressures they depend on pressure and particle size.
Abstract: Intraparticle mass transfer in coal pyrolysis is described by ternary diffusion and viscous flow, in conjunction with a simple pore model to predict concentration profiles for gases and tar. At low pressures, product yields depend on particle size only, while at high pressures they depend on pressure and particle size. Limited experimental data from a subbituminous coal confirm these trends. Data from a bituminous coal show different trends, as expected from the drastic changes the pore structure undergoes during pyrolysis.
91 citations
TL;DR: In this paper, the authors presented a model which adequately describes the kinetics of copper removal by liquid surfactant membranes and determined the kLa of this model and found to range from 1 X 10−4 to 1 x 10−3 sec−1.
83 citations
TL;DR: In this article, a new model was developed for the wall-to-bed heat transfer from solid surfaces immersed in fluidized beds, which makes use of some basic ideas adopted from the kinetic theory of gases in order to describe the mechanism of energy transfer through the moving particles.
Abstract: Heat and mass transfer in fluidized beds. Methods of calculation are presented which enable reasonably accurate prediction of heat and mass transfer coefficients in fluidized beds. Some well established equations already given in the literature could be used for estimating the range of existence of the fluidized bed and for calculating maximum fluidization velocities, bed expansion, and particle-to-fluid heat and mass transfer. However, a new model had to be developed for the wall-to-bed heat transfer from solid surfaces immersed in fluidized beds. This model makes use of some basic ideas adopted from the kinetic theory of gases in order to describe the mechanism of energy transfer through the moving particles. Predictions with this new model are in good agreement with most of the experimental observations, particularly regarding the effects of particle diameter, temperature, pressure, physical properties of gas and particles, and gas velocity.
TL;DR: In this paper, a one-dimensional model has been developed which describes the interactions among hydrodynamics, multicomponent heat and mass transfer, and reaction kinetics for the rotating disk system.
Abstract: A one‐dimensional model has been developed which describes the interactions among hydrodynamics, multicomponent heat and mass transfer, and reaction kinetics for the rotating disk system. The analysis includes variable physical properties and finite interfacial velocity and has provision for an arbitrary number of simultaneous homogeneous and heterogeneous reactions. The model has been applied to the chemical vapor deposition of silicon from silicon tetrachloride in excess hydrogen. Predictions for the dependence of silicon production rate on disk temperature and rotation rate are compared with available experimental data.
TL;DR: In this paper, a discretization technique is described, which makes it possible to calculate numerically mass transfer behavior between two media in which complex chemical reactions occur, and it has been applied to the industrially well-known system of simultaneous absorption or desorption of H2S and CO2 to or from an amine solution, accompanied by simultaneously occurring strongly interfering overall chemical reaction(s) of complex, non elementary kinetics.
01 Jan 1980
TL;DR: In this paper, it was shown that thermal (Soret) diffusion significantly alters convective mass transport rates and important transition temperatures in highly nonisothermal flow systems involving the transport of "heavy" species (vapors or particles).
Abstract: It is shown that thermal (Soret) diffusion significantly alters convective mass transport rates and important transition temperatures in highly nonisothermal flow systems involving the transport of 'heavy' species (vapors or particles). Introduction of the Soret transport term is shown to result in mass transfer effects similar to those of 'suction' and a homogeneous chemical 'sink'. It is pointed out that this analogy provides a simple method of correlating and predicting thermal diffusion effects in the abovementioned systems.
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.
01 Jan 1980
TL;DR: In this paper, the evaporation of a multicomponent droplet in a convective field is analyzed at sufficiently high Reynolds number so that internal circulation is fast with respect to diffusion.
Abstract: The evaporation of a multicomponent droplet in a convective field is analyzed at sufficiently high Reynolds number so that internal circulation is fast with respect to diffusion. The theory is an extension of a previous single component analysis to the case of any number of miscible components. The solution of the equations are shown for several two-component cases. It is found that the transient behavior prevails for both heat and mass transfer under the conditions analyzed. Even though circulation time is fast, gradients of both temperature and mass are significant, in discrepancy with the usual assumptions in this so-called ''rapid mixing'' limit. The more volatile component evaporates first from the surface, yet remains inside the core; the temperature history is then controlled by the heavy component, exceeding after some time the boiling point of the light component. This work is pertinent to synthetic fuels. 10 refs.
TL;DR: In this article, the authors reviewed the currently accepted transport coefficients needed to solve the differential equations and the simpler case in which distinction between fluid and particle temperature is unnecessary is described by the homogeneous model, and only two transport coefficients are needed here for the calculation of the temperatures and the transferred heat.
Abstract: Heat and mass transfer in packed beds. The calculation of heat transfer in packed beds and between packed beds and the surrounding walls requires knowledge of numerous different parameters, since heat is transferred by conduction as well as by radiation and convection. If it is necessary to distinguish between particle- and fluid-temperature the heat transfer is described by a system of coupled differential equations. The differential equations are based on a heterogeneous model. The currently accepted transport coefficients needed to solve the differential equations are reviewed. The simpler case in which distinction between fluid and particle temperature is unnecessary is described by the homogeneous model. Only two transport coefficients are needed here for the calculation of the temperatures and the transferred heat, namely the effective conductivity of a packed bed and the wall heat transfer coefficients. Literature references to these coefficients are reported.
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.
TL;DR: In this paper, a mathematical model for adiabatic adsorption of multiple components onto a fixed bed of adsorbent is developed, which consists of a set of coupled, hyperbolic, parial-differential equations.
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.
01 Mar 1980
TL;DR: In this article, the hydrodynamics and mass transfer behavior of an air-lift fermentor with an external loop (height 10m) was investigated by measuring gas and liquid velocities, gas hold-up, liquid mixing and oxygen transfer coefficients.
Abstract: The hydrodynamics and mass transfer behaviour of an airlift fermentor with an external loop (height 10m) has been investigated by measuring gas and liquid velocities, gas hold-up, liquid mixing and oxygen transfer coefficients. Liquid phase properties, i.e., ionic strength, viscosity and surface tension have been varied by altering the fermentation media. Results are compared with those from bubble column experiments performed in the same unit. It is shown, that more uniform two-phase flow in the airlift leads to advantages in scale-up and operation.
TL;DR: In this article, a general formalism is developed to study interfacial convective instability of two immiscible incompressible fluids, and a linear stability analysis is performed and restricted to pure longitudinal perturbations for long wavelengths.
TL;DR: In this paper, the authors presented a model which describes the mass transfer from the wet solids to a rising bubble for the case that there is no diffusion limitation inside the solids.
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.
TL;DR: The initial rate of Disperse Blue 7 dye removal from textile effluent depends on the surface mass transfer coefficient as mentioned in this paper, and the effects of certain variables namely, agitation, initial dye concentration, particle size and solution temperature, on the dimensionless mass transfer term, Sh/Sc 0.33, have been studied.
Abstract: The initial rate of Disperse Blue 7 dye removal from textile effluent depends on the surface mass transfer coefficient. The effects of certain variables namely, agitation, initial dye concentration, particle size and solution temperature, on the dimensionless mass transfer term, Sh/Sc0.33, have been studied.
TL;DR: In this article, it was shown that for a small sphere freely suspended in a linear shear flow at small Reynolds numbers, the Nusselt number N is given by, where P is the Peclet number.
Abstract: It is shown that for a small sphere freely suspended in a linear shear flow at small Reynolds numbers, the Nusselt number N is given by , where P is the Peclet number. For any given type of shear flow, the numerical value of the constant α can be obtained from a general expression derived by Batchelor (1979). The corresponding result for a particle of arbitrary shape is N/N0 = {1 − αN0P½ + O(P3/2)}−1, where N0 is the Nusselt number for pure conduction.
TL;DR: In this article, the porosity, density, and the average thickness of the corrosion product layer were determined by weight loss determinations over periods up to 210 days, and a general mathematical model was proposed to fit the experimental data with acceptable precision.