bluuebunny/crossref_metadata_2025 huggingface dataset:
A model for evaporation of a multicomponent droplet
Authors: Newbold Fred R. , Amundson Neal R.
Published: June 2004

The object of this study was to derive a model which would accurately describe the evaporation of a multicomponent droplet, especially near its boiling point. The model is derived and is shown to have the following properties: the transport of one component can be augmented by the bulk (Stefan) flow of the other components, and the droplet can never exceed its boiling point, a property not realized by previous models. The ordinary differential equations which constitute the model were integrated numerically, and results are given for both two‐ and three‐component droplets.
Suboptimal feedback control of distributed systems: Part 1. Theoretical developments
Authors: Vermeychuk J. Gregory , Lapidus Leon
Published: June 2004

A new method for suboptimal feedback control of certain classes of distributed systems based on successive instantaneous minimization of the performance functional kernel is presented. This method is applicable to both linear and nonlinear systems.

The Lyapunov functional approach is extended to distributed systems, yielding two new suboptimal feedback control techniques. Also, an application of multilevel bang‐bang control to the first‐order hyperbolic system is presented and generalized.

Advantages and disadvantage ofthe suboptimal control techniques vis á vis open loop optimal control methods are listed, as well as comparative features of the suboptimal control methods.
Miscible displacement with combined free and forced convection: Laminar flow in a vertical tube
Authors: Posner Martin , Gill William N.
Published: June 2004

An approximate analysis is given for miscible displacement in vertical tubes when density differences between the displaced and displacing fluids give rise to buoyancy forces which affect the velocity distribution significantly. The results of this analysis agree with the available experimental data fairly uniformly over the range of parameters studied experimentally.

By analogy with studies of heat transfer in vertcal tubes it is concluded that both cases studied, when a lighter fluid displaces a heavier fluid in upflow, or when the heavier fluid is below the lighter fluid, are potentially unstable flows because buoyancy forces can create points of inflection in the velocity profile; stagnation at the wall also is predicted for upflow when the lighter fluid is on the bottom initially, and this has been observed to induce a sudden transition to turbulence in heat transfer systems.

Buoyancy forces reduce the extent of dispersion by flattening the velocity profile when the heavier fluid is on the bottom in upflow. The velocity profile is elongated and the dispersion coefficient is increased when the bottom fluid is lighter than the one it displaces in upflow.
Prediction of adsorption at liquid‐solid interface from adsorption isotherms of pure unsaturated vapors
Authors: Sircar S. , Myers A. L.
Published: June 2004

Adsorption from liquid mixtures can be predicted from the adsorption isotherm of the pure unsaturated vapor, measured for each component of the liquid mixture. The theory gives analytical expressions for adsorption from liquids corresponding to Type I (finite capacity) and Type II (multilayer adsorption) vapor isotherms. The free energy of immersion of the adsorbent in the pure liquid adsorbate is the essential parameter for either type of adsorption. Predictions based upon the assumption of an ideal adsorbed solution are compared with experimental data on adsorption from liquid mixtures.
Flow rate‐pressure gradient measurements in periodically nonuniform capillary tubes
Authors: Dullien Francis A. L. , Azzam Mohamed I. S.
Published: June 2004

Flow rate‐pressure gradient measurments have been performed on 15 different test capillary tubes, each of which consisted of short, alternating segments of two different diameters. The Reynolds number range covered extended from 2 to 700, based on the conditions in the narrower capillary segment. Darcy's law was found valid up to about Re = 30‐50, whereas the Forchheimer equation described the data over the entire range of Re covered. The Forchheimer equation has been obtained from a nondimensional form of the volume averaged momentum equation by using the averaging theorem due to Slattery and to Whitaker. The parameters α and β have obtained precise hydrodynamic definitions. The experimental data have been treated in terms of the Forchheimer equation: the parameters α and β have been calculated using various definitions for the area of flow. Dimensionless permeability, equal to the ratio of measured‐to‐Poiseuille permeability has been found to be a minimum‐type function of small‐to‐large capillary diameter ratio. Dimensionless inertial parameter β* has been found to be a maximum‐type function of the capillary diameter ratio, if the calculation was based on the area of flow equal to the cross sectional area of the narrower capillary segment, in every case. The maximum occurred at the same value of the capillary diameter ratio as the minimum for the dimensionless permeability.
Thermodynamic properties of strong electrolytes in aqueous solutions
Authors: Bromley Leroy A.
Published: June 2004

A generalized analytic correlation is presented for activity coefficient. osmotic coefficient, enthalpy, and heat capacity of single and multicomponent strong aqueous solutions. A good correlation for each salt to an ionic strength of six is obtained by assigning a single parameter “B” value to each salt. These B values are well approximated by assigning two parameters for each ion. Values presented for the common ions at 25°C allow the estimation of activity and osmotic coefficients of many unmeasured salt solutions.
Restricted diffusion in binary solutions
Authors: Newman John , Chapman Thomas W.
Published: June 2004

Diffusion coefficients of binary solutions can be measured accurately by observation at long times of isothermal diffusion in a vertical cell closed at the ends (restricted diffusion). The present analysis, which accounts for the effects of solvent flux and variable solution properties, demonstrates that the experiment yields a well‐defined, differential diffusion coefficient, even in concentrated solutions.

Observation is effected by Rayleigh interference optics, and results for aqueous potassium chloride solutions confirm the accuracy of the method.
Prediction of thermodynamic properties for low temperature hydrocarbon process calculations
Authors: Lee Byung‐Ik , Erbar John H. , Edmister Wayne C.
Published: June 2004

Analytical expressions for calculating vapor‐liquid compositions, enthalpies, and entropies have been developed for hydrocarbon mixtures containing none or some of the nonhydrocarbon gases and evaluated against experimental measurements of vapor‐liquid equilibria and enthalpies. The evaluation results show that the proposed equations can be applied over wide range of conditions with good accuracy. These equations are extensions and improvements of equations presented previously by Lee and Edmister (1971c) mainly for low temperature thermodynamic property calculations.
Manufacture of silicon tetrachloride from rice hulls
Authors: Basu Prabir K. , King C. Judson , Lynn Scott
Published: June 2004

Raw rice hulls contain about 20% silica in very finely dispersed form. Pyrolyzed hulls can be chlorinated at 1000°C to give a nearly quantitative yield of silicon tetrachloride free of most other inorganic chlorides. Solid, organic, chlorine‐containing species have been found to be reaction intermediates. Commercial application appears economically attractive.
Adsorption from ternary liquid mixtures on solids
Authors: Minka Charles , Myers Alan L.
Published: June 2004

The theory of adsorption from binary liquid mixtures on solids is extended to an arbitrary number of components. An equation for the surface excess is derived in terms of the free energy of immersion of the adsorbent, the capacity of the adsorbent at saturation, and activity coefficients in the bulk and adsorbed phases.

Experimental data are reported for adsorption from binary and ternary liquid mixtures of benzene, ethyl acetate, and cyclohexane on activated carbon at 30°C. These systems exhibit nonidealities in the adsorbed phase. The theory provides accurate estimates of adsorption from the ternary mixture using data for adsorption from binaries.
Radiation profiles in an empty annular photoreactor with a source of finite spatial dimensions
Authors: Irazoqui Horacio A. , Cerdá Jaime , Cassano Alberto E.
Published: June 2004

A model of radiant energy emission for tridimensional sources has been developed and used to predict radiation flux density profiles in an annular photochemical reactor. This paper presents results for a reactor without dispersion or absorption effects; that is, reflexions and refractions have been neglected and the energy has been assumed to propagate in a transparent medium.

Computed radiation profiles agree well with published experimental data in a similar lamp‐reactor set up.

Also, the formulation does not introduce, as it is the case with all line models, any form of singularities in the prediction of radiation flux density values.

Finally, a parametric study of the effects of lamp dimensions on the shape of the radiation profiles was also made.
Correlation and prediction of gaseous diffusion coefficients
Authors: Marrero T. R. , Mason E. A.
Published: June 2004

A new correlation method for binary gaseous diffusion coefficients from very low temperatures to 10,000 K is proposed based on an extended principle of corresponding states, and having greater range and accuracy than previous correlations. There are two correlation parameters that are related to other physical quantities and that are predictable in the absence of diffusion measurements. Quantum effects and composition dependence are included, but high‐pressure effects are not. The results are directly applicable to multicomponent mixtures.
Volumetric properties of supercritical ethane‐n‐heptane mixtures: Molar volumes and partial molar volumes
Authors: Wu P. C. , Ehrlich Paul
Published: June 2004

Molar volumes were measured and partial molar volumes were calculated in the supercritical region, including the vicinity of the critical locus, lor compositions of 1.8 to 20 mole % n‐heptane. Molar volumes can he represented, to a reasonable approximation, by the Flory‐OrwollVrij (FOV) reduced equation of state. A better fit of the data is possible if the three exponents in the FOV equation are adjusted The irodified FOV equation or the Redlich‐Kwong equation, with parameters idjusted to fit the critical locus, can in general represent the partial molar rolumcs adequately along the critical locus only. The prediction of the imposition‐dependence of the partial molar volumes is only qualitatively successful at best.
Volumetric properties of supercritical ethanen‐n‐heptane mixtures: The isothermal compressibility in the critical region
Authors: Ehrlich P. , Wu P. C.
Published: June 2004

The isothermal compressibility (at constant composition x) kT,x, was calculated in the neighborhood of the critical locus for seven mixtures containing 3.5 to 19.6 mole % heptane and analyzed in terms of the reduced pressure variable σ = (P – P̂)/P̂ where P̂ is the pressure at which kT,x becomes very large. The data can be represented by the equation kT,x = const. σ−λ along the critical isotherm and one near it and by the locus P̂(T). λ was found to be a strong function of x. The divergence of the isothermal compressibility of the mixtures near the critical locus is in conflict with predictions from classical equations of state but in accordance with modern concepts of the critical region.
Separations via semicontinuous parametric pumping
Authors: Chen H. T. , Reiss E. H. , Stokes J. D. , Hill F. B.
Published: June 2004

A semicontinuous parametric pump with batch operation during one half‐cycle and continuous operation in the other half‐cycle was experimentally investigated using the model system toluene‐n‐heptane on silica gel adsorbent. A mathematical model based on an equilibrium theory is presented and is found to be in good agreement with the experimental results. Furthermore, it is shown that when the penetration distance for the cold cycle is less than or equal to that of the hot cycle and the height of the column, the rate of production of pure solvent by this pump may become quite large compared to the rate of production by a pump in which operation is continuous during both half‐cycles.
Reaction with mole changes in porous catalysts in the molecular, transition, and Knudsen regimes
Authors: Abed Ran , Rinker Robert G.
Published: June 2004

Equations are derived and solved numerically for the intrapellet pressure and composition profiles in porous catalysts. The extended dusty‐gas model is used to describe the transport for a zero‐order, irreversible reaction with mole changes. Results agree with other models in the purely Knudsen and molecular regimes. In the transition region, however, the effectiveness factor is a function of five dimensionless parameters. The calculations predict a significant pressure gradient in the Knudsen regime and transition region but an insignificant gradient in the molecular regime for reactions with mole changes. Since many industrial catalysts operate in the transition region of transport, these calculations are highly desirable in reactor design.
Perturbation methods for calculating properties of liquid mixtures
Authors: Gubbins Keith E.
Published: June 2004

Perturbation methods relate thermodynamic and transport properties of the system of interest (gas or liquid) to the known properties of some reference system; commonly used reference substances are hard sphere fluids and argon. Developments since 1967 are reviewed for both types of approach, with emphasis on applications to liquid mixtures of practical interest. Calculations for liquid mixtures of simple and complex molecules, gas solubility in liquids, fused salts, electrolytes, solvent extraction systems, and liquid metals are reviewed.
Diffusion in high viscosity liquids
Authors: Hiss Timothy G. , Cussler E. L.
Published: June 2004

The diffusion coefficients D of n‐hexane and of naphthalene in a series of hydrocarbon liquids with viscosities μ from 5 · 10−4 to 5 kg m−1 sec−1 (0.5 to 5000 centipoise) have been measured at 25°C with a one Savart plate wavefront‐shearing interferometer. This apparatus allows direct determinations at effectively infinite dilution. The values obtained suggest that for a small solute diffusing in a large solvent

a result consistent with earlier studies. The exponent of 2/3 may be rationalized on the basis of the Eyring rate theory.
Diffusion in aqueous nitric acid solutions
Authors: Nisancioḡl̄ū Kemal , Newman John
Published: June 2004

The restricted diffusion method is employed to measure the differential diffusion coefficients of nitric acid in water at 25°C for the concentration range 0.033 to 9.25 molar. The concentration gradients of diffusing solutions are observed by Rayleigh interference optics.

Experimental transport data are analyzed within the framework of the concentrated solution theory of electrolytes in order to elucidate the macroscopic transport characteristics of nitric acid in terms of specific binary interactions in solution. The results indicate that the transport properties of nitric acid are largely determined, as in other strong acids, by the hydrogen ion‐water molecule interaction.
The effect of applied force on drainage of the film between a liquid drop and horizontal surface
Authors: Hartland S. , Wood S. M.
Published: June 2004

The effect of applied force, drop volume, and physical properties on the rate of thinning of the draining films above and below a drop trapped between two horizontal surfaces has been examined theoretically and experimentally. The variation in film thickness with position and time has been obtained photographically and from capacitance measurements. The observed rate of film thinning may be predicted by the simple uniform film model with one immobile surface and, surprisingly, decreases when the applied force and drop volume increases.
Hollow fiber reverse osmosis systems analysis and design
Authors: Gill William N. , Bansal Bihari
Published: June 2004

A predictive model of hollow fiber reverse osmosis systems is developed using the equivalent annulus assumption. The fraction of feed recovered Φ depends on five parameters. Optimum values exist for the ratio of the inside to outside fiber radius ri/ro and for the outside fiber radius ro. For dilute systems, a simple closed form expression is obtained for Φ which enables one to determine optimum values easily.

The effects of pressure, temperature, flow rate, concentration, viscosity of the feed, system length, membrane rejection parameter, and number of fibers are studied. Countercurrent is superior to concurrent operation.
Dropwise condensation phenomena
Authors: Wilkins David G. , Bromley Leroy A.
Published: June 2004

Dropwise condensation of water vapor on long vertical tubes was investigated as to in situ cleaning and promoting techniques for a variety of tube materials.

Excess promoter on the tube surface significantly reduces heat transfer but appears to be slowly removed by draining.

Measured steamside heat transfer coefficients for copper, gold, Admiralty, Cu‐Ni 90‐10, and Monel tubes are adequately correlated by the theory of Mikic (1969) modifide to include the effect of wall thickness.

A photographic study revealed that falling drops are elongated into rivulets on long vertical surfaces. Short (< 65 mm) rivulets and small, barely visible drops over most of the area are evidence of excellent dropwise condensation.
Vapor‐liquid equilibrium calculations for concentrated polymer solutions
Authors: Bonner D. C. , Prausnitz J. M.
Published: June 2004

The free‐volume theory of polymer solutions initiated by Prigogine and developed by Flory and Patterson is reduced to practice. This theory, which represents a substantial improvement over the older theory of Flory and Huggins, facilitates calculation of solvent activities in polymer solutions from a minimum of experimental binary data. However, it is necessary to characterize each pure component with three molecular parameters which can be obtained from PVT data; such data, unfortunately, are often unavailable. Nevertheless, using reasonable approximations based on Bondi's correlations as needed, molecular parameters are given for 22 solvents and for 16 polymers. Binary parameters are given for 20 systems. Illustrative examples are presented.
Optimization of parallel reactions in a tubular reactor by feed distribution
Authors: Delbridge H. T. , Dyson D. C.
Published: June 2004

The System of isothermal, isobaric, perfect gas reactions with stoichiometric kinetics

equation image

taking place in a tubular reactor is considered where A3 is desired and A5 undesired. A class of optimum selectivity problems is formulated, and distributed bypass of A1 is investigated. It is shown that there are cases where the performance of the best plug flow reactor can be improved substantially (sometimes by more than 100%) by the bypass of A1, but there are also cases where bypass is fruitless.
Secondary nucleation of magnesium sulfate by fluid shear
Authors: Sung C. Y. , Estrin J. , Youngquist G. R.
Published: June 2004

The secondary nucleation of magnesium sulfate due to the action of fluid forces on a seed crystal was studied by introducing the hypothesized nuclei so generated into a region of high supersaturation. The number of nuclei observed is strongly dependent on the supersaturation at the seed and the severity of shear forces. Classical nucleation theory is used to interpret the results. These results are consistent with other experimental observations described in the recent literature on contact nucleation. The growth and nucleation process inferred is similar to that illustrated by Clontz and McCabe (1972) and suggested by Knight (1971).
Combined forced and free convection flow past a horizontal flat plate
Authors: Robertson G. E. , Seinfeld J. H. , Leal L. G.
Published: June 2004

The problem of simultaneous forced and free convection flow of a Newtonian fluid past a hot or cold horizontal flat plate is investigated by means of numerical solutions of the full equations of motion and thermal energy subject only to the Boussinesq approximation. These solutions span the parameter ranges 10 ≤Re≤ 100, 0.1 ≤Pr≤ 10, and –2.215 ≤Gr/Re5/2≤ 2.215 whereRe,Pr, andGrare based on the ambient free stream fluid properties and the overall plate lengthl. WhenGr> 0, the boundary flow near the plate surface is accelerated relative to the corresponding forced convection flow, with a resulting increase in both the local skin friction and heat transfer coefficients. WhenGr< 0, the boundary flow is decelerated, the local skin friction and heat transfer are decreased, and the flow actually separates forGr/Re5/2< –0.8 whenPr= 0.7. In the latter circumstance, an increasing degree of upstream influence is observed asGr/Re5/2is further decreased.
Application of conformational analysis techniques to the prediction of heats of formation and gas‐phase thermodynamic functions
Authors: Boyd R. H. , Breitling S. M. , Mansfield M.
Published: June 2004

Conformational energy calculations based on describing the deformation of chemical bonds by energy functions allow the prediction of molecular geometries, heats of formation, vibrational frequencies, and gas‐phase thermodynamic functions of compounds which contain bonds or groups of bonds whose properties are transferable from molecule to molecule.
On the use of Crocco's equation for the flow of power‐law fluids in a transverse magnetic field
Authors: Djukic Djordje S.
Published: June 2004

The steady laminar boundary layer flow past two‐dimensional surfaces of a power‐law non‐Newtonian electrically conducting fluid in a transverse external magnetic field is studied. The Crocco boundary layer equation is presented and, for the flow over a flat plate, solved approximately by the use of the integral method. Three examples are studied in detail. The transverse magnetic field has a greater influence on the flow of a dilatant fluid than for a pseudo plastic fluid. Increasing the magnetic field strength increases the shear stress coefficient.
Topics in computer‐aided design: Part II. Synthesis of optimal heat exchanger networks by tree searching algorithms
Authors: Pho T. K. , Lapidus L.
Published: June 2004

A compact matrix representation of an acyclic exchanger network is derived and used to generate a decision tree for the heat exchanger problem. The optimal network, which is imbedded in one of the tree nodes, is located by enumerating the entire tree using a search procedure. When this is not feasible, an alternate partial enumeration method is suggested. Sample problems ranging in size from 4 to 10 streams are used to illustrate the methods.
Measurement of mutual diffusion coefficients and thermal diffusivities by quasi‐elastic light scattering
Authors: Gulari Erdogan , Brown Ronald J. , Pings C. J.
Published: June 2004

Quasi‐elastic light scattering techniques have been employed to measure the mutual diffusion coefficient DAB as a function of concentration in eight binary mixtures and the thermal diffusivity x in nine pure liquids and two binary mixtures. The mass diffusivities obtained are typically accurate to 3% while thermal diffusivities are known to be accurate to 5%; both types of values are in substantial agreement with the available bulk values. Under most circumstances light scattering is found to offer distinct advantages over the standard techniques for determining mass and thermal diffusivities.
Liquid phase mass transfer with concurrent flow through packed towers
Authors: Ufford Raymond C. , Perona Joseph J.
Published: June 2004

Liquid phase mass transfer coefficients were measured for the absorption of carbon dioxide into water in concurrent flow. Liquid flow rates ranged up to 300 kg‐mol/min. m2 or about 60,000 lb./hr. ft.2. In comparison with countercurrent flow, the coefficients were lower by as much as a factor of 3 with significant gas rate effect. Correlations for concurrent coefficients with liquid and gas flow rates were obtained in the form kxa = CLrGs for 19.0‐mm Berl saddles and 6.35‐mm and 12.7‐mm Rashig rings.
Solubilities of gases in water and other associated solvents
Authors: Hayduk Walter , Laudie Harry
Published: June 2004

A method for estimating the effect of hydrogen‐bonding on gas solubilities in polar solvents is presented. H‐bonding factors, which are based on ideal gas solubilities and solubilities in water, appear to be closely related to H‐bonding factors in the simple alcohols. Similarly, H‐bonding factors in solvents containing a carbonly group or dihydroxy groups were related to those in acetone. The relation between the various H‐bonding factors can be used to estimate solubilities in these and other associated solvents.
Prediction of variable process performance by stochastic flow sheet simulation
Authors: Gaddy J. L. , Culberson Oran L.
Published: June 2004

The method of stochastic (Monte Carlo) simulation is employed to determine variable process performance of a 545 Mg/d ammonia plant. Operating conditions and equipment reliability are varied in a flow sheet simulation model of the process. Probability distributions of the plant production capability and failure times are generated. These data agree closely with the operating experience of an actual ammonia plant.
Liquid diffusion of nonelectrolytes: Part II
Authors: Ertl H. , Ghai R. K. , Dullien F. A. L.
Published: June 2004

Part II of the review paper covers the self‐diffusion theories and their comparison with experimental results. This is followed by a review of empirical and semi‐empirical predictive equations of mutual and self‐diffusion coefficients. Recent developments in experimental techniques for measuring liquid diffusivities are discussed in the last section. A supplement of experimental diffusion data since 1956 is available.
Intraparticle mass transport in slurries by dynamic adsorption studies
Authors: Furusawa Takehiko , Smith J. M.
Published: June 2004

Rates were measured at 25°C for the adsorption of benzaldehyde from an aqueous solution into particles of Amberlite, or activated carbon, suspended in the solution. The data for monodisperse, Amberlite particles (mean pore radius = 50Å) showed significant intraparticle diffusion resistance over the entire particle size range 200 to 900 microns (diameter). Intraparticle diffusivities were larger (tortuosity factor ∼ 0.35) than expected from pore‐volume diffusion in the liquid‐filled pores.

For the activated carbon particles (of the same size) which have a bidisperse pore‐volume distribution (pore diameter range 15 to 104Å), the effect of intraparticle diffusion was much less important and separation of the external diffusion resistance to obtain a precise value of the intraparticle diffusivity was not possible. However, De values are larger than for Amberlite and much greater than the molecular diffusivity of benzaldehyde in liquid‐filled pores. The unusually high intraparticle diffusivity seems most likely to be due to interpreting dynamic adsorption data for a bidisperse porous particle with a theory involving but one diffusivity.
Salt effects on vapor‐liquid equilibrium: Some anomalies
Authors: Meranda David , Furter William F.
Published: June 2004

Experimental data are presented for five systems, each consisting of water, an alcohol (methanol or ethanol), and an inorganic salt dissolved to saturation in the boiling liquid phase. The data confirm and extend knowledge of recently discovered anomalies to the general theory of salt effect in vapor‐liquid equilibrium. A partial accounting for the observed anomalies is attempted based on recent advances in the understanding of the structural nature of alcohol‐water mixtures.
Turbulent drag reduction in polymeric solutions containing suspended fibers
Authors: Lee W. K. , Vaseleski R. C. , Metzner A. B.
Published: June 2004

Both polymeric solutions and fiber suspensions have separately been known to exhibit drag reduction under turbulent flow conditions. It has recently been shown that the mechanisms of drag reduction differ appreciably in these two kinds of systems.

The objective of this study was to show that both mechanisms may be exploited concomitantly to achieve unusually low friction factors. Drag reductions in excess of 95% have been obtained in a 2.4‐cm tube and there is no evidence that even more dramatic results could not be obtained under optimal conditions.
New methods for suboptimal feedback control of parabolic systems
Authors: Vermeychuk J. Gregory
Published: June 2004

A new class of algorithms for the suboptimal feedback control of parabolic systems is presented. Three specific techniques within this class are developed and tested numerically using a linear example with three different types of boundary conditions. Performance of two of these techniques is found to compare favorably with that obtained by use of a rigorous open‐loop optimal control computed by the gradient method. It is also shown for linear systems having quadratic performance criteria that the new algorithms are superior to the technique presented by Vermeychuk and Lapidus (1973) in cases where state deviation has a weighting coefficient much greater than that for control energy.
Turbulent flow and mass transfer on a rotating hemispherical electrode
Authors: Chin Der‐Tau
Published: June 2004

Using the Karman‐Pohlhausen integral method, an analysis has been made for turbulent flow on a rotating hemispherical electrode mounted on an inert support rod of equal radius. The resulting friction coefficient is then substituted into the Chilton‐Colburn relation to give a rate equation for mass transfer at high Schmidt numbers. Experiments with a diffusion‐controlled electrolytic system over a range of Sc from 910 to 6,300 confirm the validity of the theory for Re > 40,000. A comparison with the results of previous heat and mass transfer measurements reveals that the turbulent flow on the present geometry is different from that on a rotating sphere and on a hemispherical electrode mounted on a support rod of larger radius.
Thermodynamic properties of sea salt solutions
Authors: Bromley Leroy A. , Singh Daljit , Ray Parthasarathi , Sridhar Srinivasan , Read Stanley M.
Published: June 2004

Based on new experimental data presented for the boiling point elevation of natural sea water solutions, smoothed tabular values are presented for boiling point elevation (BPE), osmotic coefficient, water activity, osmotic pressure, and minimum separation energy to 200°C and 12% sea salt.

The concentration of sodium chloride solutions having the same water activities as sea salt solutions is also presented.

Rigorous thermodynamics and the equations for strong electrolytes by Bromley (1973) were used for the correlation together with previously obtained heat capacity and enthalpy data and equations. A simplified equation is presented for boiling point elevation.
Scale‐up of agitated vessels gas‐liquid mass transfer
Authors: Miller Donald N.
Published: June 2004

Procedures are developed for predicting liquid film controlled mass transfer in gas sparged contactors with and without mechanical agitation. Mass transfer is shown to depend on mean bubble size. Bubble shape, motion, and interface fluctuations are all properties that are associated with bubble size, which, in turn, can be determined from the physical characteristics of the contacting system.

Experimental measurements were made on CO2 stripping from aqueous solution with air in 0.00252, 0.0252, and 0.252 m3 tanks. The vessels were geometrically similar, fully baffled, and equipped with four flat‐blade impellers and spargers. These measurements are used to evaluate earlier correlations and to develop improved scale‐up procedures.
Effect of cavitation on reacting systems
Authors: Couppis Evis C. , Klinzing George E.
Published: June 2004

When ultrasound is applied to a liquid reacting system, the reaction rates are often increased. The application of ultrasonics, therefore, provides additional modes of accelerating the reaction rates which are usually not considered by conventional mechanisms. In an attempt to study the effect of ultrasonics on chemical reactions, experimental work was undertaken in which the reaction rates of the hydrolysis of methyl acetate were measured under the presence of ultrasound. The temperature, the vapor pressure with in the cavitating bubbles, the resonance characteristics, the volume of the reacting system, and the intensity and frequency of the ultrasound are all influencing parameters on the reaction rates.
Effect of phase‐volume ratio and phase‐inversion on viscosity of microemulsions and liquid crystals
Authors: Falco J. W. , Walker R. D. , Shah D. O.
Published: June 2004

Microemulsions, which are optically transparent oil‐water dispersions, were spontaneously produced upon mixing hexadecane, hexanol, potassium oleate, and water in specific proportions. The viscosity of the microemulsions was measured for several water/oil ratios including the phase‐inversion region. The striking optical and viscosity changes observed at specific water/oil ratios were in agreement with the proposed mechanism of phase‐inversion, namely, water spheres → water cylinders → water lammellae → continuous water phase, for this system. In the phase‐inversion region, the dispersion exhibited birefringence and rheopectic properties. An extremely high viscosity (> 100,000 cps) exhibited by the dispersions between water/oil ratios of 2.0 and 3.5 were explained in terms of ion‐dipole association between oleate and hexanol molecules on adjacent droplets.
Causes, magnitude, and effects of temperature fluctuations (flickering) of catalytic wires and gauzes
Authors: Edwards W. M. , Zuniga‐Chaves J. E. , Worley F. L. , Luss Dan
Published: June 2004

An experimental study has confirmed a theoretical prediction that, when an exothermic mass transfer limited chemical reaction occurs on a single catalytic wire for which the parametera[Equation (11)] is large, temperature fluctuations (flickering) of large amplitude must be induced by concentration fluctuations. A simplified model is presented for predicting the magnitude of flickering in industrial convertors for which the parameterais usually large. The model should be useful in estimating the influence of improved mixing of the reactants on the reduction in precious metal loss from the gauze.
Facilitated transport via carrier—mediated diffusion in membranes: Part II. Mathematical aspects and analyses
Authors: Goddard Joe D. , Schultz Jerome S. , Suchdeo Shyam R.
Published: June 2004

Part II of this review is concerned with the mathematical analysis of facilitated transport. An exposition is given of the most generally useful techniques for obtaining asymptotic or approximate solutions to one‐dimensional carrier‐mediated diffusion in membranes, involving multiple permeant and carrier species which undergo one or more chemical reactions. Primary emphasis is devoted to the limiting regimes of weakly‐perturbed membranes (small driving forces) and slow or fast reactions (small or large Damkohler numbers). Many of the results appearing in the literature are unified and extended, and a systematic procedure for using these to estimate membrane performance is put forth. Finally, some areas for further work are identified.
Effect of nonuniform velocity fields and retrograde flow on distillation tray efficiency
Authors: Bell Richard L. , Solari Rodolfo B.
Published: June 2004

The effect of nonuniform velocity distributions and retrograde flow on Murphree tray efficiency has been studied. Both types of nonuniformities were shown to substantially reduce the efficiency of the tray. The results show that the presence of flow nonuniformity alone may result in significant deviations from the efficiency predicted by the AIChE model.
Statistical characteristics of thin, wavy films: Part II. Studies of the substrate and its wave structure
Authors: Chu K. J. , Dukler A. E.
Published: June 2004

Waves on falling liquid film display certain random features. At least two classes of such random waves are shown to exist; large waves which carry the bulk of the fluid and small waves which cover a substrate film that exists between large waves. It is shown that the statistics of the substrate thicknes and its wave structure can be extracted from measurements of the variation of film thickness with time. A theory is presented for calculating the mean substrate thickness and the substrate flow rate. The statistics of the wave structure is presented and compared with existing theory. The importance of the substrate in controlling transfer processes is demonstrated.
Optimal temperature policy for reversible reactions with deactivation: Applied to enzyme reactors
Authors: Haas Willard R. , Tavlarides Lawrence L. , Wnek Walter J.
Published: June 2004

The optimal temperature policy which will maximize the final catalyst activity that gives a fixed conversion of reactants in a specified time for batch operation was determined by the formulation of a calculus of variations problem following the technique of Szepé and Levenspiel (1968). The method was applied to the general case of first‐order reversible reactions which occur in the presence of catalysts deactivating by an irreversible first‐order mechanism. To reduce trial and error estimations and circumvent numerical instabilities, the two‐point boundary value variational problem was reformulated in terms of an initial value problem with a parameter which includes the initial value of temperature. This initial value problem was solved by a regression technique.

These techniques were applied to the industrially important enzymatic reaction of the isomerization of D‐glucose to D‐fructose catalyzed by glucose isomerase in solution. Kinetic and deactivation data are available for this endothermic reaction which obeys first‐order reversible kinetics and for the isomerase denaturation which appears to be first order. The optimal temperature operational policy as stated above maximized final enzyme activity such that 10% less denaturation of glucose isomerase occurred when compared to final isomerase activity yielding the same conversion for the same reaction time when the reactor is operated at the optimal isothermal temperature.
Chromatographic investigation of the oxygen exchange reaction between carbon monoxide and carbon dioxide
Authors: Smith W. D. , Deans H. A.
Published: June 2004

The theory of perturbation chromatography and isotopic tracers has been applied to the investigation of the oxygen exchange reaction between carbon monoxide and carbon dioxide in the presence of a copper‐zinc oxide catalyst at 205°C and atmospheric pressure. By analyzing the retention times of carbon‐14 monoxide and carbon‐14 dioxide tracers in six binary carbon monoxide/carbon dioxide carrier gas streams, it has been possible to shed light on the mechanism of the exchange reaction. Two types of carbon monoxide adsorption and two types of carbon dioxide adsorption were identified. Based on a numerical simulation of the experimental data, it has been concluded that the exchange reaction proceeds via the dissociative adsorption of carbon dioxide. Furthermore, the surface oxygen species formed during the dissociative adsorption of carbon dioxide appears to be the active site for the exchange reaction.
Viscous dissipation in die flows
Authors: Cox Howard W. , Macosko Christopher W.
Published: June 2004

The flow of polymer melts in cylindrical, annular, and slit dies has been examined. Large temperature rises at the outer surface of the extrudate were measured with an infrared pyrometer. Calculations show that severe radial temperature gradients exist in these flow geometries under conditions similar to those encontered in polymer processing and in viscometry measurements. A common method of estimating the average temperature rise from the total mechanical energy input seriously underestimates the maximum temperature rise.

A numerical solution of the flow and energy equations models the flow in all three geometries. A very simple Nusselt number correlation allowed an estimate of the temperature rises possible if heat transfer with the die wall occurrs. Good agreement was obtained between predicted and infrared measured melt surface temperature rises. The pressure drop gives only an indication that nonisothermal flow is occuring and is not sensitive enough to distinguish the type of heat transfer boundary condition present.

The mathematical model presented could be helpful in die design and in process modeling, allowing the designer to obtain some knowledge of the kind of flow situations which might be encountered.
Kinetics of ice crystallization in sugar solutions and fruit juices
Authors: Omran A. Monem , King C. Judson
Published: June 2004

Ice‐crystal secondary nucleation kinetics are derived from thermal response experiments carried out with concentrated sugar solutions and fruit juices. Variables studied include the level of supersaturation, power input, sugar concentration, sugar type, and the presence of high‐molecular‐weight additives. The nucleation rate is indicated to have a low‐order dependence upon subcooling (about 1.25 power) for subcoolings in the range 0.25 to 1.00°C. Fruit juices are well modeled by the corresponding synthetic sugar solution. The selection and improvement of processing approaches for freeze concentration of food liquids are discussed in light of the experimental results.
Iron oxide sorbents for regenerative sorption of NOx
Authors: Leung Linus , Gidaspow Dimitri
Published: June 2004

Supported ferric oxide can remove oxides of nitrogen from hot and cold gases, 20°C to 350°C, containing NO in the range of 50 to 1000 ppm when sufficient oxygen is present. Rates of sorption and capacities increase with oxygen concentration. The sorbent can be regenerated with air at 400° to 450°C an indefinite number of times.

Reduced iron oxide sorbs nitric oxide more rapidly than the ferric oxide and has a higher capacity. It can be regenerated with hot reducing gases.
Corresponding states. III. Henry's constants for nonpolar binary mixtures
Authors: Gunn Robert D. , Yamada Tomoyoshi , Whitman David
Published: June 2004

A Henry's constant correlation is developed from a macroscopic Corresponding states theory for fluid mixtures. The method requires three interaction parameters which are correlated for mixtures of paraffin with nitrogen, carbon dioxide, hydrogen sulfide, or another paraffin. Henry's constants can be calculated by this method to within experimental accuracy (about ± 5%) for the mixtures tested.
Models of secondary nucleation attributable to crystal‐crystallizer and crystal‐crystal collisions
Authors: Evans T. W. , Sarofim A. F. , Margolis G.
Published: June 2004

The rate of secondary nucleation of ice, assumed to be proportional to the product of collision frequency and impact energy, has been quantitatively modeled using idealized representations of collisions between crystals and either other crystals or surfaces in the crystallizer. The crystal‐crystallizer collisions were assumed to be driven by either steady or turbulent fluid motion and the crystal‐crystal collisions were assumed to be driven by either gravitational forces or turbulent eddies. The models predict to a good approximation the experimentally determined dependence of the secondary nucleation of ice on crystal size, ice concentration, and agitation power.
Convective instabilities in concurrent two phase flow: Part I. Linear stability
Authors: Gumerman Raymond J. , Homsy George M.
Published: June 2004

The linear stability of thermally stratified horizontal two‐phase Couette flow is analyzed for the case of a constant vertical temperature gradient. Instabilities driven by buoyancy, surface tension gradients, or shear are allowed for. It is shown that the instability can take three possible forms: streamwise oriented roll vortices, long interfacial waves, and short Tollmien‐Schlichting waves. It is shown that the stability limits for rolls are identical to those for plane, stagnant layers. A long wave expansion is presented and the stability limits for this mode are given algebraically. The nonexistence of a Squire's Theorem is demonstrated and some numerical experiments at moderate Reynolds numbers are described. Detailed comparisons with previous work are possible for only one fluid pair, but it is shown that reasonably accurate statements may be made to determine which mode may manifest itself in any given experimental situation.
A semimicro thermomechanical technique for characterizing polymeric materials: Torsional braid analysis
Authors: Gillham John K.
Published: June 2004

An overview of a nondestructive semimicro mechanical technique–pioneered, developed, and exploited by the author–which is used for characterizing phase transitions and transformations in polymeric materials is presented. Particular attention is given to literature published since January, 1972, which pertains to advances in automation, data acquisition and processing, and application to polymeric systems. The instrument has been consolidated as a powerful and convenient mechanical spectrometer in this short period.
Dense–bed column crystallizer: An experimental and analytical study
Authors: Moyers Charles G. , Olson Jon H.
Published: June 2004

The performance of a continuous, vertical, dense‐bed column crystallizer is evaluated by comparing experimental and predicted column temperature profiles and by examining product composition at various operating conditions. The separation obtained in an eutectic system is modeled by a component conservation equation coupled with a nonadiabatic energy balance equation. The critical parameter in the analysis is the axial dispersion coefficient and the measured values of this coefficient were similar in magnitude to those reported for ice washing columns. The dense‐bed column apparently achieves nearly ideal plug flow.
Interfacial effects in the entrapment and displacement of residual oil
Authors: Slattery John C.
Published: June 2004

Qualitiative theories are developed to explain the roles of surface tension and the two surface viscosities during the entrapment of residual oil by water and during the subsequent displacement of residual oil by surfactant solutions. The results are in agreement with available experimental data concerning the effects to be observed as the oil‐water surface tension is reduced. Limited data suggest an order of magnitude criterion for the critical surface tension above which no residual oil can be recovered. The two surface viscosities do not affect the entrapment of residual oil, but they are predicted to play a major role in the displacement of residual oil by surfactant solutions.
Mass transfer in a fixed‐bed gas‐liquid catalytic reactor with concurrent upflow
Authors: Snider James W. , Perona Joseph J.
Published: June 2004

Mass transfer coefficients for the hydrogenation of α‐methylstyrene were measured in a packed‐bed reactor with concurrent gas and liquid upflow. The packing was 0.29‐cm alumina spheres coated with palladium catalyst. Mass transfer coefficients increased as the 1/2 power of the liquid rate and increased with gas rate to a gas phase Reynolds number of about 50. The severe decrease for higher gas rates may be due to pulsing flow.