bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid‐vapor equilibrium in the system helium‐methane
Authors: Heck C. K. , Hiza M. J. 
Published: June 2004

AbstractLiquid and gas phase compositions for the system helium‐methane have been measured at 15° intervals from 95° to 185°K. up to 200 atm. pressure. Data for these seven isotherms were taken in a gas phase recirculation apparatus with chromatographic analysis. In most regions the phase compositions obtained are thought to be within ± 3% of the mole fraction of the minor component. The maximum deviation from the enhancement factor curve at the lowest concentration levels was 16%. These data are in excellent agreement with most of the very recent data but are in poor agreement with the older data for this system.
Generalized solution of the tomotika stability analysis for a cylindrical jet
Authors: Meister Bernard J. , Scheele George F. 
Published: June 2004

AbstractThe stability of cylindrical jets in immiscible liquid systems is analyzed with the low velocity theory of Tomotika. For the first time the several limiting solutions in the literature are obtained from a general equation, so approximate restrictions on their applicability can be presented. These restrictions show that for many systems none of the limiting solutions is valid. Correlations applicable to all Newtonian liquid‐liquid systems are presented for predicting the growth rate and wavelength of the most unstable disturbance.
Process control by digital compensation
Authors: Mosler H. A. , Koppel L. B. , Coughanowr D. R. 
Published: June 2004

AbstractDiscrete control algorithms, suitable for programming in a direct digital control computer, are presented. For processes whose dynamics can be adequately modeled as first order with delay, digital compensation algorithms are derived to yield theoretically a response with finite settling time, when the system is step forced in either set point or load. The utility of the proposed designs is experimentally verified by application to a higher order physical process whose dynamics are not fully described by the model. The results demonstrate that sampling frequencies may be reduced considerably below presently accepted values while still maintaining transient response characteristics of the system comparable with those obtainable from conventional continuous control.
Flow characteristics of horizontally moving stable aqueous foams
Authors: Weissman Eugene Y. , Calvert Seymour 
Published: June 2004

AbstractAn empirical study was made of the flow characteristics of a stable aqueous foam (based on dilute solutions of saponin) moving horizontally inside a duct. Characteristic foam data have been determined experimentally, namely, drainage, interfacial areas, and related dimensions such as lamella thickness and foam cell size, fractional liquid holdups, foam velocities, and extent of gas channeling through the foam. Simple correlatability of drainage, interfacial area, and fractional liquid holdup in terms of basic parameters such as the liquid flow rate entering the apparatus, and the longitudinal position in the duct has been demonstrated. The sometimes simple dependence on the geometry of the perforated gas‐liquid contactor and on the physical properties of the foaming solutions (surface tension and bulk viscosity) has also been described.
Mass transfer in rectangular cavities
Authors: Jarrett E. L. , Sweeney T. L. 
Published: June 2004

AbstractThe captured vortex system produced by the flow of a fluid along a plate containing a transverse rectangular cavity was investigated by measuring the local mass transfer coefficient kg on the cavity walls. Both transverse and peripheral kg profiles are presented for cavity depth‐to‐length ratios of 0.5, 1.0, and 2.0 at free‐stream velocities of 6.8, 13.5, and 27 ft./sec. for water evaporating into air. These profiles reflect the three‐dimensional nature of the flow in the cavity.
Estimation of dispersion and hydrogen bonding energies in liquids
Authors: Wiehe I. A. , Bagley E. B. 
Published: June 2004

AbstractIt is proposed that the product of the molar volume and the internal pressure is a measure of the dispersion interaction energy in liquids regardless of the presence of other intermolecular forces. If this is true, then the energy of interaction due to hydrogen bonding may be estimated for hydrogen bonding liquids by the difference between the energy of vaporization and the product of the molar volume and the internal pressure. It is also shown that Small's group contribution technique provides a good estimate of internal pressure of hydrogen bonding liquids.
A dynamic method for the study of heterogeneous catalytic kinetics
Authors: Bennett Carroll O. 
Published: June 2004

AbstractFor a trial multistep mechanism for a heterogeneous catalytic reaction, it is suggested that dynamic experiments can be used to calculate the forward and reverse rate constants of individual steps. The experiments consist of the measurement of the composition of the effluent from a continuous stirred‐tank catalytic reactor as a function of time as the input composition to the reactor is perturbed. The method of moments is used to obtain the kinetic constants for a trial mechanism from the experimental data.
Unsteady diffusion in ternary gas mixtures
Authors: Arnold K. R. , Toor H. L. 
Published: June 2004

AbstractUnsteady diffusion in the system methane‐argon‐hydrogen was studied in a Loschmidt apparatus with large changes in concentration. The mean concentration‐time history was predicted within experimental error by the linearized equations of multicomponent mass transfer. In the calculations the Stefan‐Maxwell equations were used to obtain the diffusivity matrix which was evaluated at the equilibrium concentration.Digital computer solutions to the nonlinear differential equations were also obtained for various systems and boundary conditions. The fluxes predicted by the linearized equations with the diffusivity matrix evaluated at the arithmetic average of the initial and boundary concentrations were in all cases within 5% of the numerical predictions.
Linear, steady, two‐dimensional flows of viscoelastic liquids
Authors: Marrucci Giuseppe , Astarita Gianni 
Published: June 2004

AbstractThe general form of the equations describing a steady, two‐dimensional flow of an incompressible liquid is reduced to a form containing only two parameters. The histories of stress and of deformation of a material element are written explicitly. A second‐order, slow‐flow approximation and a Maxwell type of constitutive equation are used to infer properties of the rheological behavior of viscoelastic liquids in such flows.
Drop size distribution in agitated liquid‐liquid systems
Authors: Chen Hsiao Tsung , Middleman Stanley 
Published: June 2004

AbstractThe drop size distributions resulting from the agitation of immiscible liquids were measured over a wide range of parameters. The average drop size is correlated by \documentclass{article}\pagestyle{empty}\begin{document}$ \overline D _{32}/L $\end{document} = 0.053 NWe−0.60. The distribution function for volume fraction is normal and depends only upon \documentclass{article}\pagestyle{empty}\begin{document}$ \overline D _{32} $\end{document}. The results are valid for very dilute solutions wherein coalescence of droplets plays no role in the dispersion mechanism.
Drop size distributions in strongly coalescing agitated liquid‐liquid systems
Authors: Sprow F. B. 
Published: June 2004

AbstractEmulsion drop size distributions have been measured at various locations in a turbine mixer for the methyl isobutyl ketone‐salt water system. The drop sizes are strongly dependent on the sampling position, being smallest near the impeller tip and largest at the bottom of the mixing tank. The variation of drop diameter with impeller speed has been studied and indicates that droplet breakup predominates near the impeller, whereas the coalescence of emulsion droplets can be controlling in other locations.
Polymer reactors and molecular weight distribution: Part II. Free radical polymerization in a batch reactor
Authors: Hamielec A. E. , Hodgins J. W. , Tebbens K. 
Published: June 2004

AbstractThe free radical polymerization of styrene in benzene was studied theoretically and experimentally over ranges of monomer and catalyst (AIBN) concentrations and temperature in an isothermal, stirred batch reactor. Molecular weight distributions were measured with a gel permeation chromatograph. Tung's hermite polynomial method was used to correct for imperfect resolution.The differential rate equations have been solved to predict the conversion of monomer and molecular weight distribution of the polymer as a function of time. These solutions were used to interpret the experimental rate data.Good agreement between theory and experiment was found for narrow and broad distribution, provided the variation of the termination constant with solvent concentration was accounted for.The agreement between the experimental and calculated molecular weight distribution suggests the utility of gel pemeation chromatography in the investigation of polymer reaction kinetics.
Nonlinear convective diffusion: A hyperfiltration application
Authors: Nakano Yoshisuke , Tien Chi , Gill William N. 
Published: June 2004

AbstractA nonlinear unsteady state convective diffusion problem that describes the performance of a constant pressure cell is studied. The cell can be used to either determine membrane constants or to carry out batch filtration operations. It consists of a cylinder closed by a semipermeable membrane at one end and a piston at the other.The nonlinear partial differential equation governing the system was solved by both integral methods and the use of a similarity transformation. The similarity approach formulates the solution in the form of an infinite series and reduces the problem to finding the solution of an infinite system of ordinary differential equations. The series solution can be considered to be exact but its convergence is questionable for large values of time in the event B ≠ 0; when B = 0, the convergence is substantially better.Approximate solutions obtained by integral methods were examined in detail. It was found that the results obtained by these methods can involve serious errors, under certain circumstances, and these errors seem unpredictable a priori. Consequently, it is concluded that considerable care should be taken in the use of integral methods for solving mass transfer problems in which the velocity field is coupled with the convective diffusion equation and its boundary conditions.The numerical results obtained in this work are sufficiently comprehensive to be used, in conjunction with experimental data, to determine membrane constants which are required for the design of both continuous and batch membrane separation systems.
Vapor‐liquid equilibria at high pressures: Calculation of partial molar volumes in nonpolar liquid mixtures
Authors: Chueh P. L. , Prausnitz J. M. 
Published: June 2004

AbstractThermodynamic analysis of high‐pressure vapor‐liquid equilibria requires information on the effect of pressure on liquid phase fugacities; this information is given by partial molar volumes in the liquid mixture. A method for predicting these partial molar volumes is presented here. First, molar volumes of saturated liquid mixtures are computed by extending to mixtures the corresponding states correlation of Lyckman and Eckert. These mixture volumes are then used to calculate partial molar volumes with an expression based on a modification of the Redlich‐Kwong equation. At high pressures partial molar volumes are strong functions of the composition and in the critical region, may be positive or negative. Calculations are sensitive to the characteristic energy between dissimilar molecules; this energy is generally lower than that given by the geometric‐mean rule. Calculated results are in good agreement with experimental data for seven systems containing paraffinic and aromatic hydrocarbons, carbon dioxide, and hydrogen sulfide.
Some experiments on the Marangoni effect
Authors: Suciu D. G. , Smigelschi Octavian , Ruckenstein Eli 
Published: June 2004

AbstractAn experimental study of the spreading and dissolving of thin liquid films under the action of surface forces is presented. The method consists of the continuous feeding of a liquid over the surface of another liquid into which it dissolves; the steady film thus obtained covers only a part of the supporting liquid surface, dependent on the flow rate of the liquid fed. The dependence of the radius of the film contour on flow rate and concentration driving force is obtained for various film forming liquids dissolving into water. By using a Schlieren technique the film contour and the flow pattern outside the film contour are studied, several structures being evidenced.
Slug flow heat transfer with mass injection and linearly varying wall temperature
Authors: Yu W. S. , Chen John C. 
Published: June 2004

AbstractThe purpose of this study was to determine the two‐dimensional temperature field for a fluid in slug flow through tubes with uniform mass injection and linearly decreasing wall temperature. A series solution was obtained, the first ten eigenvalues for which were determined from the characteristic equation by the method of Runge‐Kutta. Expressions for local conductive heat flux at the tube wall and local Nusselt number were obtained as a function of inlet Peclet number, injection Peclet number, tube radius, temperature boundary conditions, and fluid properties. Sample results are presented for several injection rates at different wall temperature conditions. In general, mass injection was found to decrease the local heat flux and increase temperature driving force causing a decrease in the Nusselt number.
Performance of packed columns: Part VIII. Liquid flow patterns and velocities in packed beds
Authors: Shulman H. L. , Mellish W. G. 
Published: June 2004

AbstractTo develop a basis for a better understanding of the behavior of the liquid phase in packed columns, liquid velocities and flow patterns were studied at several typical points in a column packed with 1.0‐in. porcelain Raschig rings with a high‐speed photographic technique. Liquid velocities were found to fluctuate rapidly with time. Laminar flow predominates, but mixing occurs at junctions between pieces of packing. A complex model is required to describe the behavior of the liquid phase in packed columns.
Pressure drop in geometrically ordered packed beds of spheres
Authors: Susskind Herbert , Becker Walter 
Published: June 2004

AbstractThe pressure drop of water was measured when water flowed through a bed of stainless steel ball bearings packed in an ordered rhombohedral geometry. Experiments were carried out with eleven different packed beds, encompassing the entire range of the square‐base array, in the same 10.85 by 10.85 by 30‐in. rectangular test column in a forced circulation loop at modified Reynolds numbers up to 17,000. The test variables included water velocity, bed voidage, spacing between adjacent balls, ball diameter, and bed height. Curves of friction factor vs. Reynolds number are presented. An increase in the relative horizontal spacing between balls was found to have a more important effect than an increase in voidage in decreasing the pressure drop. A general correlation relating the mutual effects of bed voidage and ball spacing on pressure drop that would bring all the data points together, especially in the transition flow region, could not be found. As a result, the system appears to consist of two distinct parts separated at the minimum packing density. A correlation was found only for the first, but from a practical point of view more important, region. Data may be corrected for bed voidage, but only for small variations in ball spacing, by the ratios of (1 − ε)/ε3 at the two voidages. No entrance and exit effects could be measured beyond the first seven ball layers.
Continuous, dissolved‐air ion flotation of hexavalent chromium
Authors: Grieves Robert B. , Ettelt Gregory A. 
Published: June 2004

AbstractAn experimental investigation is presented of the ion flotation of dichromate from aqueous solution with a cationic surfactant and using a non‐ionic polymer as a flocculant aid. A dissolved‐air, continuous flow unit is used (with a surfactant‐dichromate premix period of 1 hr.) with a feed rate of 120 liters/hr. of a stream containing from 25 to 100 mg./liter of dichromate. Within the ranges of the variables studied, optimum results are obtained with a molar surfactant to dichromate feed ratio of about 2, a feed polymer dosage of about 3% of the dichromate feed concentration, a recycle rate 200% of the feed rate, and a column detention time of 35 min. With an air requirement of 0.043 liters of air (at STP)/liter of feed delivered at 40 lb./sq. in. gauge, feed streams containing from 25 to 100 mg./liter of dichromate can be readily reduced to 10 mg./liter of dichromate and 30 mg./liter of surfactant. The primary advantage of the process lies in the concentration of dichromate, surfactant, and polymer in a small liquid volume of collapsed foam, less than 1% of the total feed throughput. Foam concentrations are of the order of 10,000 to 20,000 mg./liter of dichromate.
Discrete dynamic optimization applied to on‐line optimal control
Authors: Rafal Marshall D. , Stevens William F. 
Published: June 2004

AbstractA general method has been developed for controlling deterministic systems described by linear or linearized dynamics. The discrete problem has been treated in detail. Step‐by‐step optimal controls for a quadratic performance index have been derived. The method accommodates upper and lower limits on the components of the control vector.A small binary distillation unit was considered as a typical application of the method. The control vector was made up of feed rate, reflux ratio, and reboiler heat load. Control to a desired state and about a load upset was effected.Calculations are performed quite rapidly and only grow significantly with an increase in the dimension of the control vector. Extension to much larger distillation units with the same controls thus seems practical.
Crystal size distributions in continuous crystallizers when growth rate is size dependent
Authors: Abegg C. F. , Stevens J. D. , Larson M. A. 
Published: June 2004

AbstractEmpirical size‐dependent growth rate models are studied for their effect on the population density distributions from a continuous, mixed suspension, mixed product removal (CMSMPR) crystallizer. The growth rate models and/or their corresponding population density distributions are examined for continuity, convergence of moments, versatility, and their ability to fit experimental data.A new empirical size‐dependent growth rate model is proposed which has properties superior to those of previous models. Experimental steady state data are presented to illustrate the application of the model to actual CMSMPR crystallization systems.
Local compositions in thermodynamic excess functions for liquid mixtures
Authors: Renon Henri , Prausnitz J. M. 
Published: June 2004

AbstractA critical discussion is given of the use of local compositions for representation of excess Gibbs energies of liquid mixtures. A new equation is derived, based on Scott's two‐liquid model and on an assumption of nonrandomness similar to that used by Wilson. For the same activity coefficients at infinite dilution, the Gibbs energy of mixing is calculated with the new equation as well as the equations of van Laar, Wilson, and Heil; these four equations give similar results for mixtures of moderate nonideality but they differ appreciably for strongly nonideal systems, especially for those with limited miscibility. The new equation contains a nonrandomness parameter α12 which makes it applicable to a large variety of mixtures. By proper selection of α12, the new equation gives an excellent representation of many types of liquid mixtures while other local composition equations appear to be limited to specific types. Consideration is given to prediction of ternary vapor‐liquid and ternary liquid‐liquid equilibria based on binary data alone.
Mathematical modeling and numerical integration of multicomponent batch distillation equations
Authors: Distefano G. P. 
Published: June 2004

AbstractA mathematical model for multicomponent batch distillation was derived, and a FORTRAN IV program was written for solution on a digital computer. The program has been used in the simulation of several commercial batch distillation columns.A calculation procedure for the numerical solution of batch distillation equations starting from total reflux steady state conditions was developed, and the step‐by‐step procedure is presented here. Also included is a discussion of the stability and relative computational effectiveness of various numerical integration techniques when applied to transient distillation calculations. The discussion applies equally well to both batch distillation and unsteady state continuous distillation.
Stability of batch catalytic fluidized beds
Authors: Luss Dan , Amundson Neal R. 
Published: June 2004

AbstractThis work is a study of the stability of a batch fluidized bed with a simple model. It is shown that multiple steady states can occur with all catalyst particles at the same temperature, some of these states being unstable. If the initial temperature of all the particles is not the same, a special kind of steady state, in which particles of different temperatures can coexist in the bed, might be obtained. The number of these pathological steady states is not finite, and the conversion obtained may be very different from that obtained by a uniform steady state.The analysis has demonstrated that the initial temperature of the catalyst particles may be a predominate factor in determining the kind of steady state obtained. For the case of uniform catalyst particles, a simple stability analysis has been developed. Several numerical solutions of the transient equations were performed to investigate the possible responses of the system to disturbances of various steady states.
Measurement of the velocity of gases with variable fluid properties
Authors: Wasan D. T. , Davis R. M. , Wilke C. R. 
Published: June 2004

AbstractThis paper describes the experimental measurements of the time‐averaged velocities of gases in a field of variable composition and temperature. The conventional theory of hot‐wire anemometry is extended to include the effects of both natural and forced convection to gases having variable fluid properties. Observations of the fully developed turbulent velocity fields in the presence of moderate mass transfer rates revealed no significant effect of mass transfer on the velocity distribution.
Kinetics of reaction and crystallization in condensed phases: The aqueous potassium dipicrylamine system
Authors: Savage H. R. , Butt John B. , Tallmadge John A. 
Published: June 2004

AbstractAn apparatus and experimental technique were developed for the study of the kinetics of relatively rapid reaction and subsequent crystallization in condensed phases. The method employs batch experiments to establish the integral of crystallization rate over ranges of pertinent external variables.The crystallization of potassium dipicrylamine from aqueous solution, a system of potential interest in application to potassium recovery from brines, was studied experimentally. It is shown that both reaction and crystallization rate parameters may be determined from the data on the basis of the consecutive rate model developed; application of the Burton‐Cabrera‐Frank theory of crystal growth to this system is demonstrated.