bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct contact heat transfer between immiscible fluid layers in laminar flow
Authors: Mukerjee Dipankar , Davis E. James 
Published: June 2004

AbstractThe problem of heat transfer (and, by analogy, mass transfer) between immiscible fluids in laminar parallel flow is analyzed as a conjugated boundary value problem. Exact solutions are developed in terms of known functions by solving for the temperature fields in the two phases separately for constant boundary conditions, then generalizing the results to obtain solutions for the interfacial temperature distribution and the complete temperature field for the conjugated system. The analysis and the results of calculations for heat transfer between two immiscible films flowing down an adiabatic inclined plane are presented. It is shown that axial conduction can be included, and the effects of axial conduction in one stream are examined. The predicted Nusselt numbers are plotted versus axial position for various parameters, and the interfacial temperatures and mixed mean fluid temperatures for the two phases are plotted to elucidate the heat transfer characteristics.
Hydrodynamic stability of viscoelastic fluids: Importance of fluid model, overstability, and form of disturbance
Authors: McIntire L. V. , Schowalter W. R. 
Published: June 2004

AbstractA linearized stability analysis has been applied to a fluid flowing in a gravity field between horizontal planes in Couette flow under conditons such that the temperature of the bottom plane exceeds that of the top. It is shown that, under conditions likely to be encountered with polymer solutions, oscillatory instabilities will not be controlling. Criteria are offered for ascertaining when an analysis based upon a second‐order fluid model may be expected to yield physically meaningful results. It is also shown that for the fluid model considered, critical conditions for stability are not changed when disturbances which vary in the flow direction are substituted for those which are a function of the coordinate transverse to the flow.
Drop sizes in an agitated liquid‐liquid system
Authors: Mlynek Youval , Resnick William 
Published: June 2004

AbstractThe relationship between drop size and location in an agitated liquid‐liquid system was investigated, with a new sampling method in which the dispersion was sampled in a specially designed trap and immediately encapsulated by a polymer film. The liquid‐liquid system used was water and a mixture of isooctane and carbon tetrachloride with a density closed to that of the water. Dispersed phase holdup was varied from 0.025 to 0.34 volume fraction.For this system, which has low mutual sulubility and high interfacial tension, there is almost no dependence of drop size on location for the mixing geometries studied. This was due to the fact that the coalescence rate is low compared to the circulation time. An increase in impeller speed and drop size decreased the coalescence rate while an increase in holdup increased it.The mean drop diameter was related to the Weber number and holdup by an equation. By comparison of mean drop diameters obtained using different impellers, it was shown that the criterion of equal power per volume can be used for estimating drop size when going from one mixing geometry ot another, not too different, geometry at moderate impeller speeds.
Kinetics of slow thermal chlorination of hydrogen in nickel tubular flow reactors
Authors: Bernstein Leonard S. , Albright Lyle F. 
Published: June 2004

AbstractThe first reliable kinetic data and correlations yet reported were obtained for the thermal reaction of gaseous chlorine and hydrogen over a wide range of operationg conditions. Earlier data had been obtained in reactors that result in irreproducible data. The results of the present investigation clarify the reaction sequence that consists of both gas‐phase and surface reactions.
Some performance characteristics of spray columns
Authors: Vedaiyan S. , Degaleesan T. E. , Laddha G. S. , Hoelscher H. E. 
Published: June 2004

AbstractExperimental data on the drop size distribution obtained from multiple nozzles in a spray column are presented and analyzed. For nozzles having a diameter above the critical size, the distribution pattern change from near normal monomodal to bimodal and back again to monomodal but skewed toward the larger size fraction. There is no change in the observed maximum drop size in the distribution with flow rate except near the critical velocity region. Drop breakup mechanisms appear to be different from the above pattern for nozzles below a critical size.A model is proposed for prediction of the complete range of drop sizes observed.
Mass transport and reaction in sulfonic acid resin catalyst: The dehydration of t‐butyl alcohol
Authors: Heath H. W. , , Gates B. C. 
Published: June 2004

AbstractKinetics of the dehydration of t‐butyl alcohol to isobutylene were measured with a semibatch reactor containing liquid reactant and suspended particles of cation exchange resin catalyst [sulfonated copolymer of styrene and divinylbenzene (DVB)]. Effects on rate were determined for variations in temperature (58 to 76°C.), reactant water mole fraction (0.0005 to 0.10), and catalyst pacticle diameter (77 to 620 μ) and crosslinking (2 to 12% DVB).Nearly anhydrous t‐butyl alcohol failed to penetrate the shrunken network of the polymer. Reaction ebgan only on particle peripheries, and product water penetrated the gel network and s welled it to allow penetration of the alcohol. Rate consequently increased to a maximum (about 0.5 moles/min. equivalent of catalyst SO3H groups at 76°C.) and then decreased as water competed with reactant fro catalytic sites. A spherical catalyst particle is modeled as a shrinking cetrol core, free of reactant and water, and a swollen shell in which concent rations are independent of position and time. The model fits reaction rate and separate particle swelling data for 80 μ particles of catalyst containing 12% DVB, but it is increasingly inadequate for larger particles and catalysts of lower DVB contents.
Separations via continuous parametric pumping
Authors: Chen H. T. , Rak J. L. , Stokes J. D. , Hill F. B. 
Published: June 2004

AbstractA continuous pump in which the feed and product streams flow steadily both in upflow and downflow is experimentally investigated in the model system toluene‐n‐heptane on silica gel adsorbent. The experimental data compare reasonably well with analytical results based on an equilibrium theory. The operating conditions necessary to achieve high separation factors are shown to be dependent on the relative magnitudes of penetration distances and the height of the column.
Identification, hysteresis, and discrimination in enzyme kinetic models
Authors: Tanner Robert D. 
Published: June 2004

AbstractThree kinetic rate constants and an initial enzyme concentration are estimated in Britton Chance's classical peroxidase model by applying both the Picard iteration‐orthogonal polynomial and stationary state methods to his transient experimental data. Since this model does not describe the hysteresis exhibited by the data, more complex models are examined in order to account for this behavior. From a study of this hysteresis phenomena which is inherent to the structure of consecutive reactions, it is found that in addition to discriminating between mechanisms much useful information about the history of enzyme induction can be observed from the direction, shape, and area of the hysteresis loop.
Secondary nucleation in a class II system: Ammonium sulfate‐water
Authors: Youngquist Gordon R. , Randolph Alan D. 
Published: June 2004

AbstractSecondary nucleation at low supersaturation for the ammonium sulfate‐water system was studied using a seeded continuous crystallizer. Counter size distribution measurements in the subsieve size range indicated that nuclei are formed by microattrition of seed crystals and that the growth rate of the nuclei is very small. Nucleaion rate was correlated with the characteristics of the secondary environment. The results of this correlation, which shows strong dependence on stirring rate and essentially linear dependence on solids concentration, indicate that secondary nuclei are generated by collisions of the seed crystals with the impeller blades.
Application of modern control theory to distillation columns
Authors: Hu Y. C. , Ramirez W. Fred 
Published: June 2004

AbstractModern control theory for systems with load changes is applied to distillation column control. Both linear and nonlinear distillation models are developed and tested. Excellent control is achieved by using an optimal multi‐variable‐proportional‐integral (MPI) controller for systems with unmeasurable disturbances. When the disturbances are measurable an optimal multi‐variable proportional controller with error coordination (MPE) is desirable. Various structures for distillation control have also been investigated.
Multicomponent diffusion and vapor‐liquid equilibria of dilute organic components in aqueous sugar solutions
Authors: Chandrasekaran S. K. , King C. Judson 
Published: June 2004

AbstractA technique for direct measurement of the differential diffusion coefficients in a ternary system of water, sugar, and a dilute organic species is described. The individual sugars were d‐fructose, d‐glucose, and sucrose; and ethyl alcohol, ethyl acetate, n‐butyl acetate, and n‐hexanal individually constituted the dilute organic species. The four ternary diffusivities were obtained over a range of sugar concentrations by the use of horizontal diaphragm cells, a differential interferometer, a flame‐ionization gas‐liquid chromatograph and postulation of the validity of the Onsager reciprocal relations. The equilibrium partial pressures of the dilute organic species over these solutions have also been measured, using a vapor head space chromatographic technique.
The interrelationship between bubble motion and solids mixing in a gas fluidized bed
Authors: Haines A. K. , King R. P. , Woodburn E. T. 
Published: June 2004

AbstractThe stochastic differential equations for particle motion in a homogeneous fluidized bed have been modified to incorporate a bubble‐particle interaction. In a freely bubbling bed this interaction causes an instantaneous random step upwards when a particle collides with a bubble. In addition the particles are subject to a Brownian Motion due to particle‐particle interactions and to a vertical drift velocity. The particle motion was modeled by the set of stochastic differential equations

where N and W are Poisson and Wiener processes respectively. U is the velocity vector, X the vertical coordinate, Y and Z the horizontal coordinates. This set of equations has been solved and the form of the probability density function p(x, t) has been obtained. Predictions are in terms of the mean bubble frequency at a point λ the average displacement associated with a particle‐bubble collision, and the dense phase diffusion coefficient.The main result is that the effective diffusion coefficient in the vertical direction is given by

where E is the dense phase diffusion coefficient and 1/α is the average displacement suffered by a particle on collision with bubble.The model was tested experimentally using random forcing function techniques. All parameters were evaluated independentely; λ by direct measurement and the other two inferred from available published data. The predictions of the theory agreed well with experimental observations of the solids dispersion.
The stress state of elastic fluids in viscometric flow
Authors: Miller M. J. , Christiansen E. B. 
Published: June 2004

AbstractA new method of instrumentation for normal‐stress determinations was developed, making possible accurate unsteady state as well as steady state measurements, eliminating errors arising from fluid‐filled pressure‐tap holes, and permitting the determination of the complete stress state in a single cone‐and‐plate shearing‐geometry experiment. Sensitive, nonflow semiconductor pressure transducers mounted at several radial positions with their pressuresensing diaphragms flush with the plate surface provide data for the normal‐stress distribution. The normal‐stress distribution, together with the total normal force from the single‐geometry experiment, enables determination of the primary and secondary normal‐stress differences by two independent methods of analysis while the transmitted torque enables determination of the viscosity, each as a function of shear rate. Only the normal‐stress distribution is required if an independent check on the normal‐stress determination is not desired. Similar advantages arise in the application of the instrumentation to a parallel‐plate shearing geometry, The new instrumentation was used in the determination of the complete rheological stress state of three aqueous and two “Tetralin” solutions of polymers in a cone‐and‐plate shearing geometry shear rates of 0.02 to 450 s−1 on a Model R‐17 Weissenberg Rheogoniometer. The normalstress differences computed by means of two methods of analysis are in surprisingly good agreement. The ratio of the secondary to the primary normal‐stress difference was negative. The absolute values of this ratio decreased with increases in the shear rate, the maximum observed value being 0.4.
Finite element analysis of slow non‐newtonian channel flow
Authors: Palit Kalipada , Fenner Roger T. 
Published: June 2004

AbstractA finite element method is applied to isothermal slow channel flow of power‐law fluids. The fully developed flow is normal to the channel cross section. The method and results are compared with a finite difference method for rectangular channels and with exact solutions for the Newtonian case. An advantage of finite element methods is the flexibility of the mesh of elements approximating the continuum, chosen to suit the particular problem. Arbitrary boundary shapes can be handled as illustrated by a rectangular channel with rounded corners.
Prediction of drop volumes in liquid–liquid systems
Authors: Izard John A. 
Published: June 2004

AbstractA method is described for calculating drop sizes obtained in Newtonian immiscible liquid‐liquid systems when a dispersed fluid is continuously injected at uniform subjectting point velocities through a sharp‐edged nozzle that is preferentially wet by the continuous phase. This method is based on the calculation of the shape of a drop forming at the nozzle tip by means of a pressure balance over the drop interface and the use of a force balance to determine if any portion of the forming drop can break away. Calculated drop sizes are compared with experimental data for systems of different physical properties.
The florite‐water vapor sorption therm
Authors: Jury Stanley H. , Edwards Harold R. 
Published: June 2004

AbstractThe sorption isotherms for moist air and Florite were determined at a total pressure of one atmosphere and 75°, 100°, 125°, 150°, 175°, and 200°F. No hysteresis was evident.An investigation of the sorption isotherms showed that a concentration‐temperature coordinate could be identified, which when plotted against amount sorbed, causes all sorption isotherms to collapse into a single sorption therm.For purposes of sorption curve fitting the concentration‐temperature coordinate was incorporated into a version of BET theory. This relation produced an excellent fit of data without resorting to more complicated versions of BET theory.The concentration‐temperature coordinate was also incorporated into a modified version of Langmuir‐Hey theory to show that this interpretation also leads to a very satisfactory fit of sorption data.Some additional observations are made concerning the computerized curve fitting technique as applied to silica gel, the data for which were reported in an earlier publication.
Minimum realizations and system modeling. I. Fundamental theory and algorithms
Authors: Rossen R. H. , Lapidus L. 
Published: June 2004

AbstractThis review article surveys representative literature on minimum realizations and system modeling. This theory makes possible the construction of minimum size state‐space models directly from experimental input/output data. Theoretical developments, numerical algorithms, and the connection with other methods of identification of linear systems are covered. Partial minimum relaizations which are extensions of the concepts developed are also included. A numerical example illustrates many of the techniques.
Liquid counterdiffusion of selected aromatic and naphthenic hydrocarbons in type Y zeolites
Authors: Satterfield Charles N. , Cheng Chon S. 
Published: June 2004

AbstractRates of Counterdiffusion are markeldy affected not only by the critical molecular diameter of the diffusing molecules but also by other physicochemical properties of the liquids and the nature of the cation in the zeolite. The effective diffusivity in NaY or HY under counterdiffusion conditions is less by a factor of 10−1 to 10−3 than that for unidirectional diffusion into an initially empty pore structure.
HI‐H2 vapor etch for low temperature silicon epitaxial manufacturing
Authors: Dyer Lawrence D. 
Published: June 2004

AbstractEtching of semiconductor silicon slices at 998°C with HI‐H2 mixtures was developed to the level that practical etch rates (≥ 0.1 μm/min) and smoothness of surfaces were obtained in a manufacturing type reactor without the addition of HF or He. Such a low temperature etch is expected to lead to improved device characteristics, mainly because of more sharply defined junction surfaces.Using deposition at 998°C on very clean slices as a testing method, two sources of impurities that cause stacking faults in the deposition layers were identified and eliminated. These were the polypropylene vessel used in the slice cleanup procedure, and the hydrogen peroxide used in conjunction with sulfuric acid in the primary cleaning step.
Controller design for distributed systems via bass' technique
Authors: Baker Thomas E. , Brosilow Coleman B. 
Published: June 2004

AbstractBass' feedback controller design technique is extended to distributed parameter systems and its use is illustrated for a parabolic system with boundary control.The development of the design technique rests on a conjecture concerning the necessary and sufficient conditions for the asymptotic stability of linear time invariant partial differential equations. It is shown through a study of the discretized analog of a distributed system that the most likely candidate for a Lyapunov functional general enough to yield the necessary and sufficient conditions for asymptotic stability is a double integral with a symmetric kernel.
Nearly optimal control of a pilot plant distillation column
Authors: Merluzzi P. , Brosilow C. B. 
Published: June 2004

AbstractA nearly optimal on‐off control strategy, previously applied to a rectification column, has been successfully implemented on a full distillation column. The controller employs a linear combination of temperature measurements to adjust the reflux flow rate in order to maintain a desired overhead product composition. A simple relationship between the control coefficients is shown to be characteristic of countercurrent systems. This relationship allows the controller to be tuned on‐line by the adjustment of a single parameter, thereby eliminating the need for a dynamic model of the process and for lengthy design calculations.The performance of the tuned on‐off controller is compared with that of a tuned proportional plus integral controller and a single measuremnt on‐off controller for feed flow disturbances and set point changes. Results show that the multi‐measurement on‐off control system is superior for both types of disturbances.
Kinetics and mechanism of the epoxidation of unsaturated fatty acids
Authors: Abraham M. E. , Benenati R. F. 
Published: June 2004

AbstractA study was made of the epoxidation of octadecenoic acids with peroxybenzoic acid in benzene. Activation energies, frequency factors, enthalpies of activation, entropies of activation, and free energies of activation were obtained for the following fatty acids: cis‐9‐octadecenoic acid (oleic), trans‐9‐octadecenoic acid (elaidic), 12‐hydroxy‐cis‐9‐octadecenoic acid (ricinoleic), 12‐hydroxy‐trans‐9‐octadecenoic acid (ricinelaidic), cis‐11‐octadecenoic acid (vaccenic), and cis‐6‐octadecenoic acid (petroselinic). It was observed that the reaction rate was adversely affected by the proximity of the carboxyl group, that is, the closer the carboxyl to the reaction site the lower the rate. A shift from a trans to a cis configuration results in an approximate 50% increase in reaction rate with a corresponding decrease in free energy of activation of 260 cal/mol. The effects of isomerism and the replacement of substituent groups on the reaction rate were generally additive. A mechanism for the peroxydation of octadecenoic acids is proposed.
Investigation of the thermodynamic behavior of the system, acetone‐carbontetrachloride, by the equilibrium sedimentation technique
Authors: Sethy Anil , Cullinan Harry T. 
Published: June 2004

AbstractThe equilibrium sedimentation technique for the direct determination of the chemical potential composition derivatives of a liquid mixture is applied to the binary system acetone‐carbontetrachloride. Equilibrium concentration profiles obtained in an ultracentrifuge are used with the Wilson equation to quantitatively determine the composition variation of the activity coefficients over the entire range of composition. Results agree well with previous data and indicate the technique to be accurate and reliable.
Equilibrium, thermodynamic, and transport properties of polyatomic gases from molecular structure
Authors: Galloway T. R. 
Published: June 2004

AbstractThe possibility of predicting physical properties for polyatomic gases entirely from molecular structure has been explored. Intramolecular force constants for the bonds can be drawn from spectroscopically established tables and applied successfully to molecules involving a large variety of structures. A vibrational analysis of the molecule using these constants yields the thermodynamic functions of the ideal gas. The intermolecular pair potential parameters for the spherical core model of Kihara can be obtained quantitatively from molecular constants, and this potential can be used in obtaining the dilute gas transport properties. A linear relationship was found between the Kihara sphereical core size and Pitzer's acentric factor. Also from the Kihara model the critical constants are derived, which allows one to use Pitzer's compressibility tables for the dense gas corrections to the ideal gas law and the excess functions of the thermodynamic quantities. A complete package of computer programs which predict all important physical properties directly from input name alone has been written and tested. Suggestions are given for future work needed to improve many of the techniques presented.
Minimum realizations and system modeling: II. Theoretical and numerical extensions
Authors: Rossen R. H. , Lapidus L. 
Published: June 2004

AbstractThe ideas and techniques discussed in Part I of this ReviewPart I of this paper was published in the July, 1972, AIChE Journal.
are extended to the modeling of nonlinear lumped and distributed systems. Troublesome numerical and computational difficulties are examined, and recommendations for the alleviation of these difficulties are made. Particular emphasis is placed on the stability of system models constructed with the Tether method. Highly successful modeling of realistic systems are presented numerically.
Losses of mercury from chlorine plants: A review of a pollution problem
Authors: Caban Reinaldo , Chapman Thomas W. 
Published: June 2004

AbstractThe problem of mercury losses from chlorine plants is reviewed. The mercury material balance is difficult to establish because mercury escapes from the process by a number of routes. Some of the reasons for the mercury emissions are explored, and some problems involved in the measurement of mercury in various effluents are discussed.A number of mercury containment processes for specific streams have already been proposed, but the need for an integrated mercury recycle policy still exists.