bluuebunny/crossref_metadata_2025_split huggingface dataset:
Washing of the liquid retained by granular solids
Authors: Han Chang Dae , Bixler Harris J. 
Published: June 2004

AbstractA mathematical model termed the blind side channel model is developed to describe the washing performance of liquid retained in a bed of granular solids. The effects of operating variables and system's parameters, such as the flow rate of wash liquor, the diffusivity of the liquid system, and the thickness of the bed, are discussed. The experimental washing study was carried out with granular solids such as glass beads, sand, and crystalline solids, and application of wash liquors miscible in all cases with the residual liquid in the bed, drained by centrifuging. Results from the developed model showed very good agreement with the experimental results. The developed model would be valuable in analyzing the washing performance for process improvement and in designing washing systems.
Translation of continuous phase in the wakes of single rising drops
Authors: Hendrix Charles D. , Dave Shashikant B. , Johnson Homer F. 
Published: June 2004

AbstractVolumes translated in wakes of single drops of organic liquids rising through aqueous media have been measured. Organic drops studied comprised methyl isobutyl ketone, toluene, and toluene‐carbon tetrachloride mixtures. Aqueous media comprised water and water‐sugar solution. Distance of drop rise varied from 10 to 20 in. Drop size was varied such that Reynolds numbers of 40 to 800 were obtained. Volumes translated were nearly independent of distance for nonoscillating drops and decreased rapidly with distance for oscillating drops. Transition from nonoscillating to oscillating drops occurred at Reynolds number of 200. Measurements of drop velocities were also made.
Continuous flow in packed thermal diffusion columns
Authors: DiCave Sergio , Emery Alden H. 
Published: June 2004

AbstractA parallel‐plate thermal diffusion column packed with glass wool was operated in continuous flow. The standard equation used for continuous flow through nonpacked columns satisfactorily correlates separation and flow rate. The packed‐column theory correctly gives the effects on the regression coefficients of plate spacing and packing permeability, the two variables unique in the packed column. The theory gives poor approximations of the absolute magnitudes of the coefficients, however, which is the same situation found in results from nonpacked columns.
Dynamic behavior of the well‐mixed isothermal crystallizer
Authors: Sherwin M. B. , Shinnar Reuel , Katz Stanley 
Published: June 2004

AbstractUnder some conditions, continuous crystallization exhibits cyclic changes of the particle size even with constant input conditions. A linearized stability analysis has been performed to determine under what conditions this behavior can be expected. Numerical solutions of the actual nonlinear system equations were carried out to follow the cyclic behavior and to compute the cycle time and the amplitude of the fluctuations. The effect of seeding on the stability limits and product distribution was also evaluated.
A predictive theory for diffusion in mixed solvents
Authors: Cullinan Harry T. , Cusick M. R. 
Published: June 2004

AbstractA relationship for the diffusion coefficient of a dilute species in a mixture of two solvents is developed. The result, based on the linear additivity of the frictional activation energy which is valid for completely miscible, nonassociated systems, predicts the diffusion coefficient of the solute in terms of the limiting values of the diffusion coefficient of the solute in each of the solvents, the limiting values of the solvent pair diffusion coefficient, and two thermodynamic factors. The equation is confirmed for some recent experimental data.
Heat transfer in packed and fluidized beds by the method of cyclic temperature variations
Authors: Lindauer George C. 
Published: June 2004

AbstractParticle‐to‐gas heat transfer coefficients were determined in packed and fluidized beds with large diameter particles and high mass velocities using the cyclic temperature method.Experimental results for packed beds were satisfactorily correlated within 10% deviation as εjh vs. NRe and were found to compare favorably with results of other experimenters obtained with much lower mass velocities and larger particles. The particle‐to‐gas heat transfer coefficient varied as G0.60 for the steel spheres vs. G0.66 for the tungsten spheres, and as Dp−0.44.Heat transfer coefficients obtained at minimum fluidization were in good agreement with those obtained with packed beds. As the mass velocity was increased above that required for minimum fluidization, heat transfer coefficients remained essentially constant.
Motion of spherical particles in a Bingham plastic
Authors: Ansley Ralph W. , Smith Terence N. 
Published: June 2004

AbstractThis paper describes an investigation of the settling characteristics of spherical particles in Bingham plastic fluids. A stress analysis is used to derive a nondimensional parameter which describes the laminar settling regime. The terminal velocities of spheres in the Reynolds number range of 2 to 130 have been determined. These, together with published data at higher Reynolds numbers, are shown to substantiate the theoretical argument.A correlation of drag coefficient as a function of the settling parameter indicates the transition from laminar to turbulent settling.
Kinetics of physical adsorption of propane from helium on fixed beds of activated alumina
Authors: Rimpel Auguste E. , Camp David T. , Kostecki John A. , Canjar Lawrence N. 
Published: June 2004

AbstractThe kinetics of physical adsorption of propane from helium on fixed beds of activated alumina at 30°C. and at atmospheric pressure was studied. Two grades of activated alumina with the same average pore size distribution but different pore size distributions were used. Gas concentration, flow rate, and adsorbent particle size were also varied. The rate of internal diffusion controlled the adsorption process and was best described by Ficks' equation for unsteady state diffusion into a sphere. The internal diffusion appeared to be by a pore diffusion rather than by a surface diffusion mechanism.
Nonlinear feedforward control of chemical reactors
Authors: Luyben William L. 
Published: June 2004

AbstractThis paper illustrates the synthesis of nonlinear feedforward controllers for chemical reactors. In most of the theoretical development and application of feedforward control only linear systems have been considered. There are, however, no inherent linear limitations in feedforward control. Since chemical reactors are usually nonlinear, the effectiveness of control should be improved by including nonlinearities in the design of feedforward controllers. This is particularly true for batch reactors because of the large changes in variables during a batch cycle. Continuous stirred‐tank reactors are studied with single and consecutive reactions of first and higher order. Effectiveness of linear and nonlinear feedforward controllers is compared for disturbances of various magnitude and direction. Feedforward control of batch and tubular reactors is also discussed.
Mass transfer through horizontal liquid films in wavy motion
Authors: Goren Simon L. , Mani R. V. S. 
Published: June 2004

AbstractThe effect of standing waves of controlled amplitude and frequency on the steady state rate of mass transfer through thin horizontal liquid layers is studied experimentally. The variables studied are the film thickness, the amplitude and frequency of the waves, and the spacing between the probes generating the waves. A bulk motion of complicated pattern known as drift is caused by the finite amplitude of the waves. The rate of mass transfer in the absence of imposed vibration is two to three times greater than that expected by molecular diffusion alone. Vibration increases the rate up to an order of magnitude or more, depending on the hydrodynamic conditions. The data at low frequencies are correlated by an expression of the form (i‐io)/idiff = KAf3/4h1/2L−1/2.
A kinetic approach for polymer solution data
Authors: Kim H. T. , Brodkey Robert S. 
Published: June 2004

AbstractThe phenomenological theory previously prsented for describing the rheological properties of non‐Newtonian materials was applied to two polymer solution systems. The basic shear diagram is needed over a wide range of shear rates and polymer concentrations, and such data are not readily available; however, what could be found supported the analysis. In order to confirm the theory further, ten solutions of polymethylmetacrylate in diethyphthalate with concentrations up to 55% were investigated at 40°C. The results indicated that the forward and reverse orders were 1 and 2 respectively and that the two parameters of the theory (a susceptibility to shear term and an equilibrium type of constant) were constant over the range of concentrations investigated. The flow data were reproduced to within a few percent for all solutions, although the errors were large for the very dilute concentration, where experimental difficulties precluded obtaining reliable data. The method allows correlation of polymer solution data over the range from lower to upper Newtonian viscosities and over a wide concentration range.
Studies of intramembrane transport: A phenomenological approach
Authors: Kaufmann Thomas G. , Leonard Edward F. 
Published: June 2004

AbstractThe intramembrane transport properties of carbohydrates were investigated in cellophane. The experiments performed were the measurement of net volume transfer under a concentration and pressure gradient and the solute transfer due to a concentration difference together with the physical properties of the membrane. The matrix of phenomenological coefficients characteristic to the transport was established after the phase boundary contributions were extricated from the experimental transport data. These thermodynamic coefficients were then interpreted through the Spiegler‐Kedem‐Katchalsky frictional model.The analysis of the frictional coefficients clearly indicated the importance of solute‐polymer interactions. The magnitude of solute‐solvent frictional coefficients in the membrane were compared with the corresponding interactions in free solutions. Their differences were explained in terms of the interaction of the solute with the macromolecular network and were quantitatively expressed by introducing two reduced frictional coefficients. The tortuosity factor was shown to be related to these interactions and not a simple geometric property of the membrane. The temperature dependence of the frictional coefficients was established.
The effect of eccentricity on the terminal velocity of the cylinder in a falling cylinder viscometer
Authors: Chen M. C. S. , Lescarboura J. A. , Swift G. W. 
Published: June 2004

AbstractThe theoretical equations for the flow of Newtonian fluids in a falling cylinder viscometer with eccentricity are developed. The error in fall velocity of the cylinder caused by eccentricity is determined and presented in tabular form. An approximate method to determine the error in fall velocity caused by eccentricity for non‐Newtonian fluids of the power law type is also presented. For the Newtonian case, n=1, the approximate method is shown to give excellent agreement with the exact method.
Effect of pressure gradient on sonic‐point heat transfer
Authors: Talmor Eliyahu 
Published: June 2004

AbstractAn analytical investigation of gas side heat transfer in high contraction, high convergence flows is presented. A partical criterion for retransition of a turbulent boundary layer is derived from the integral momentum equation and the effect of pressure gradient in the turbulent boundary‐layer flow regime is described with the help of external flow relations. The validity of the analytical results is demonstrated by comparison to available internal and external flow, throat heat transfer data.Accordingly, various turbulent boundary‐layer heat transfer levels are obtained depending on the sonic‐point pressure gradient, the specific heat ratio, the reference‐to‐stagnation temperature ratio, and the exponent of the viscosity‐temperature function. Furthermore, the pressure gradient and the superficial mass velocity have opposite effects on the onset of retransition of a turbulent boundary layer.
Creeping flow of power‐law fluid over newtonian fluid sphere
Authors: Nakano Yoshisuke , Tien Chi 
Published: June 2004

AbstractA technique which is a combination of Galerkin's method and variational principle was developed and used for the approximate solution of creeping flow of power‐law fluid over a Newtonian fluid sphere. The stream functions (both internal and external) and drag coefficient are expressed in terms of three parameters: the flow behavior index of the power law fluid, the external Reynolds number, and a viscosity ratio parameter \documentclass{article}\pagestyle{empty}\begin{document}$${\rm X} = \frac{{\mu ia^{n - 1} }}{{KV_{\alpha ^{n - 1} } }}$$\end{document}. Comparisons with existing experimental data are also given.
Analysis of optimal composite feedback‐feedforward control
Authors: Luecke R. H. , McGuire M. L. 
Published: June 2004

AbstractWe have developed analytic design methods for combination feedback‐feedforward control systems and have evaluated systems yielding optimal performance while subject to constraints commonly encountered in the chemical industry. Using the mathematical techniques pioneered by Wiener for the solution of the design equations, we have based the optimization on minimization of the mean square output of a system subject to a random disturbance. Side conditions for the constraint on mean square control effort, signal‐to‐noise ratio in the feedback system, and minimization of error output caused by misidentification of plant parameters were found to be necessary to give physically realizable and meaningful designs. The analytic design methods are useful for analysis of control system performance and capabilities under a variety of constraints, but the optimal designs are marginally superior to ideal or invariant feedforward controllers coupled with tuned proportional feedback controls. The principal improvement in the optimal design is in conservation of control effort when compromises in system performance are necessary because of this restriction.
The rise velocity of bubbles in tubes and rectangular channels as predicted by wave theory
Authors: Maneri Charles C. , Mendelson Harvey D. 
Published: June 2004

AbstractIn a previous paper, an analogy was presented which related the rise velocity of bubbles in liquids of infinite extent to the velocity of surface waves over infinitly deep liquids. In the present paper, a corresponding analogy is found which relates bubble velocities in bounded liquids to wave velocities over liquids of finite depth.
Pool boiling heat transfer to cryogenic liquids; I. Nucleate regime data and a test of some nucleate boiling correlations
Authors: Kosky P. G. , Lyon D. N. 
Published: June 2004

AbstractPool nucleate boiling heat transfer curves for pure nitrogen, oxygen, argon, methane, and carbon tetrafluoride have been measured on a horizontal, flat, circular, platinum plated disk for saturation pressures ranging from 1 atm. or less to the immediate vicinity of the critical pressure for each liquid. The results have been compared with various suggested nucleate boiling correlations, and the correlations of McNelly, of Kutateladze, and of Borishanskiy‐Minchenko are found to be roughly equally successful and all distinctly superior to those of Rohsenow, of Gilmour, and of Forster and his collaborators for these liquids. For oxygen, argon, methane, and carbon tetrafluoride, boiling hysteresis of a type not previously reported was observed at intermediate and high saturation pressures on this surface.
Quasilinearization, difference approximation, and nonlinear boundary value problems
Authors: Lee E. Stanley 
Published: June 2004

AbstractA finite difference method combined with the quasilinearization technique is used to solve the nonlinear two‐point boundary value problems. This method does not have the stability problem connected with the marching integration techniques. A scheme which can be used to reduce the rapid access memory requirements of digital computers is also proposed. The steady state equations resulting from mass and energy balances in a tubular reactor with axial diffusion are solved by this method. With very poor initial approximations, only three to seven iterations are needed to obtain the correct answer.
Mass transfer across mobile interfaces
Authors: Angelo J. B. , Lightfoot E. N. 
Published: June 2004

AbstractThe dependence of extraction efficiency on flow distributions and droplet boundary‐layer behavior was investigated in a specially designed sieve‐tray extractor. Flow patterns and drop trajectories were obtained from residence‐time distributions and photographic observation. Extraction efficiency and continuous phase residence times were determined by a pulse technique.For most runs, flow behavior could be adequately described by the assumptions of perfect mixing in the continuous phase and plug flow of the drop phase. However, drop velocities were higher than predicted by single drop correlations, and the flow pattern was sensitive to minor changes in operating conditions. Observed extraction efficiencies were in good agreement with predictions based on observed flow patterns and the two film, surface stretch, mass transfer model of Angelo and Lightfoot. Approximately 90% of the stage mass transfer effectiveness appears to be due to the drop rise period, and essentially all the remainder to drop formation for the stage geometry selected.The greatest obstacle to reliable prediction of extractor performance is uncertainty as to the effect of operating conditions on flow distribution.
An introduction to the stability of distributed systems via a liapunov functional
Authors: Berger Albert J. , Lapidus Leon 
Published: June 2004

AbstractLiapunov's direct method is extended to determine the stability of distributed systems with single and multiple equilibrium profiles. The method is simple to apply and makes use of certain inequalities to establish the sign definiteness of the time derivative of the Liapunov functional. Two numerical examples are presented, the adiabatic catalyst particle and an empty adiabatic tubular reactor with axial diffusion.
Tubular flow photoreactors for complex, nonchain kinetics
Authors: Harano Yoshio , Smith J. M. 
Published: June 2004

AbstractThe stationary state hypothesis, commonly used for intermediates in complex kinetics in batch reactor studies, is analyzed in a tubular flow photoreactor. For practical values of the rate constants for the chosen kinetic sequence, it appears that the hypothesis is valid over all but a short entrance region of the reactor for both streamline and plug flow models. Even though the stationary state is quickly achieved, for the normal range of diffusivities, the conversion to product may be affected by radial diffusion and velocity profiles.In the course of the analysis the pertinent dimensionless parameters establishing the behavior of the reactor were identified. These arose from the differential equations expressing the conservation of radiant energy and mass in the system.
The dynamic behavior of a packed liquid extraction column
Authors: Doninger Joseph E. , Stevens William F. 
Published: June 2004

AbstractThe dynamic behavior of a packed liquid extraction column was investigated by comparing experimental frequency response data obtained from pulse testing with theoretical frequency response data. The theoretical model, which assumed that the column can be represented by a series of perfectly mixed cells, did not adequately describe the frequency response characteristics of the extraction process. However, by the utilization of various magnitude and phase correction factors, a technique was developed to obtain a semiempirical model that could be used to duplicate the actual performance of the liquid extraction column.
The steady state behavior of crystallizers with classified product removal
Authors: Han C. D. , Shinnar Reuel 
Published: June 2004

AbstractMany industrial crystallizers incorporate some classifying devices. This paper deals with the steady state behavior of such systems. A method is described by which the particle size distribution can be calculated for any classifier, provided the crystallizer itself can be considered as a mixed vessel. The method is based on the use of residence time distribution and the escape probability or intensity function introduced by Shinnar and Naor. The effect of classification on crystallizer performance is discussed with the help of some illustrative examples.
Enhancement of film condensation rate on vertical tubes by longitudinal fins
Authors: Thomas David G. 
Published: June 2004

AbstractLongitudinal rectangular fins loosely clamped to vertical tubes markedly increase the film condensation heat transfer coefficient. At a heat flux of 2×104B.t.u./hr.sq.ft., twelve ⅛×0.013 fins clamped to a ½ in. O.D. vertical tube 42 ½ in. long (thus doubling the surface area of the tube) gave a condensation coefficient of 15,000 ± 15% B.t.u./hr.sq.ft. °F. compared with 1,620 B.t.u./hr.sq.ft. °F. for the same tube without fins, a ratio ofh/hoof 9.2. The enhancement of the film condensation coefficient decreases as the heat flux increases and as the number of fins decreases.A model based on the effect of fin shape on film and rivulet hydrodynamics explains the observed behavior.
The application of theoretical diffusion models in the presence of a catalytic reaction
Authors: Sterrett J. S. , Brown L. F. 
Published: June 2004

AbstractThe fundamental problem in this work was to determine if methods of predicting mass transport rates in porous catalysts, developed from theory in the absence of chemical reaction, are valid in the presence of reaction. By using the ortho‐para shift of hydrogen over a ferric oxide gel catalyst as the reacting system, the effective diffusivity within the catalyst was determined from kinetic data on five different particle sizes of the catalyst. This effective diffusivity was then compared with that predicted by three different procedures recently published. These procedures predicted diffusivities approximately 40% below the experimentally obtained diffusivity. Although the differences between the experimental and predicted effective diffusivities can be regarded as within the limitations of the accuracy of the predictions, the observed differences may also be caused by some form of surface transport.
Generalized solution of freezing a saturated liquid in a convex container
Authors: Tao Luh C. 
Published: June 2004

AbstractComputer results of the required time to freeze completely a pure liquid in a container shaped like a slab, a cylinder or a sphere are correlated by equations which converge to the asymptotic solutions of the problem. Variables are grouped into dimensionless parameters so that these equations are applicable to any given system.
Correlations for adsorption of a binary gas mixture on a heterogeneous adsorbent—the methane‐ethane‐silica gel system
Authors: Masukawa Shigehiko , Kobayashi Riki 
Published: June 2004

AbstractCorrelations for the adsorption of a binary gas mixture on a heterogeneous adsorbent have been developed for both mobile and immobile models. Experiments determined the form for the expression of the surface heterogeneity, and only one dimensionless constant for the molecular size was required.The correlations were tested by experimental data on the system methane‐ethane‐silica gel. For the same amount of adsorption the root‐mean‐square deviation of calculated versus experimental fugacity ranged from 4.1 to 5.2% for methane and from 2.7 to 3.4% for ethane at 5.0, 15.0, 25.0, and 35.0°C. for surface coverage ranging from zero to monolayer and for the complete composition range. The system at these conditions is classified as highly mobile based on examination of spreading pressure curves, both experimental and calculated based on the correlations.