bluuebunny/crossref_metadata_2025 huggingface dataset:
The wetting behavior of azeotropic systems at atmospheric and reduced pressures
Authors: Boyes Adrian P. , Ponter Anthony B.
Published: June 2004

Contact angles are reported for the azeotropic systems n‐propanol‐water and benzene‐cyclohexane measured under distillation conditions at total reflux over a pressure range 50 to 760 torr on both copper and polytetrafluoroethylene surfaces. The influences of the solid surfaces, the surface tension positive and negative nature of the liquids, together with the changes accompanying the azeotropic shift with pressure on the wettability, have been established and shown to conform with wetting theory.
Mass transfer to a rotating fluid. Part II. Transport from the base of an agitated cylindrical tank
Authors: Colton Clark K. , Smith Kenneth A.
Published: June 2004

Mass transfer to the base of an unbaffled cylindrical tank which is agitated by an axially‐mounted impeller is studied experimentally and theoretically. Measured local mass transfer coefficients vary with radial position and fall within theoretical bounds derived for the case of a fluid undergoing solid body rotation above the boundary layer on the base. Average mass transfer coefficients and torque delivered to the base are fitted by consistent theoretical expressions, and an empirical correlation is developed for calculating the average liquid phase mass transfer coefficient.
Precipitate coflotation of orthophosphate and fluoride
Authors: Bhattacharyya Dibakar , Romans John D. , Grieves Robert B.
Published: June 2004

Orthophosphate and fluoride are simultaneously precipitated from aqueous solution, 5.26 × 10−3 M. in each, by La (III). The precipitates are cofloated by the anionic surfactant sodium laurylsulfate, with optimum flotation at pH 4.0 and a stoichiometric lanthanum concentration based on LaPO4 and LaF3. Over pH 3.5 to 6.0, better than 95% flotation of the total orthophosphate and precipitated fluoride that‐are present can be floated at a molar sodium laurylsulfate to orthophosphate plus fluoride ratio of 0.023. At lower sodium laurylsulfate concentrations, the flotation decreases at pH 3.5 and 6.0 compared to pH 4.0–5.0; at pH 4.0, an increase in the La(III) concentration decreases the flotation.
Error bounds for approximate solutions to nonlinear ordinary differential equations
Authors: Ferguson Noble B. , Finlayson Bruce A.
Published: June 2004

Error bounds are provided for approximate solution of systems of nonlinear ordinary differential equations for cases where there is no known exact solution for comparison. Theorems are proved for problems of heat and mass transfer of a multicomponent system in catalyst particles under going chemical reaction. Error bounds are provided for the pointwise error as well as the effectiveness factor. Calculations based on the theorems show the orthogonal collocation method can give results which are proved accurate to 12 digits, thus providing essentially the exact solution. For problems for which the theorems have not yet been proved, the results suggest that the mean‐squared residual gives a good indication of the accuracy since the error decreases as the mean‐squared residual decreases.
Interfacial instability and spontaneous formation of microemulsions
Authors: Shah D. O. , Tamjeedi A. , Falco J. W. , Walker R. D.
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 drop‐volume measurements of hexadecane‐water interface in the presence of hexanol or potassium oleate revealed that these surfactants decrease the interracial tension of the hexadecane/water interface. It is proposed that the interaction between these two emulsifiers at the oil‐water interface causes spontaneous negative interfaical tension resulting in interfacial instability and the formation of microemulsions.

As the amount of water is increased, the microemulsion exhibits a clear to turbid to clear transition. Unlike the clear regions, the turbid region possesses birefringence. The development of birefringence is also accompanied by a sharp decrease in electrical resistance. High‐resolution (220 Mc) nuclear magnetic resonance data suggest that water exists in two distinct environments or structures in the birefringent region. The electrical, birefringence, and nuclear magnetic resonance data agree with the proposed mechanism of phase‐inversion of microemulsions, which can be described as water spheres to water cylinders to water lamellae to a continuous water phase. The spontaneous formation of such structures (for example, water cylinders and lamellae) presumably depends upon the phase‐volume ratio and the interfacial tension at the oil‐water interface.
Fixed bed desorption behavior of gases with non‐linear equilibria: Part I. Dilute, one component, isothermal systems
Authors: Zwiebel Imre , Gariepy Roger L. , Schnitzer Jay J.
Published: June 2004

Generalized depletion curves for desorption (and breakthrough curves for adsorption) were calculated for a system characterized by the Langmuirtype equilibria and controlled by a film type rate model. The depletion points generally appear sooner than the corresponding breakthrough points, and the desorption profiles are significantly broader than the corresponding adsorption curves. These phenomena may be best explained in terms of the prevailing driving forces. The effects of adsorbate properties and operating variables (inlet composition and flow rate) were established and experimentally substantiated.
Finite element analysis of two‐dimensional slow non‐newtonian flows
Authors: Palit Kalipada , Fenner Roger T.
Published: June 2004

A finite element method is applied to isothermal incompressible two‐dimensional slow flows of power‐law fluids. Examples considered are rectangular and axisymmetric converging channel flows, recirculating flows in rectangular channels, and flow round cylinders. Results are successfully compared with both finite difference and analytical solutions. The flexibility of finite element methods makes them very suitable for problems involving complex boundary geometries. The method used is particularly suitable for non‐Newtonian flows and can treat both rectangular and axisymmetric geometries.
Computation of vapor liquid equilibria for hydrogen and light hydrocarbon systems
Authors: Singh Surendra P. , Mukhopadhyay Pranab K.
Published: June 2004

Generalized expressions are presented for Henry's constants and self‐interaction constants required in the Chueh‐Prausnitz method for predicting the vapor‐liquid equilibria for hydrogen and light hydrocarbon systems, The K‐values calculated using the above correlations were compared with the K‐values obtained from the published experimental data in the teperature range of 117 to 422°K. The statistical analysis shows that the cal‐ culated values are about as reliable as the experimental results.
Experimental evaluation of nonisotheral solid‐gas reaction model
Authors: Wang S. C. , Wen C. Y.
Published: June 2004

The nonisothermal unreacted‐core‐shrinking model with unsteady state heat transfer analysis has been experimentally evaluated. The system studied is the combustion of a single agglomerated carbon‐fire clay sphere in a thermobalance. By comparing the experimental results with those predicted by the model, it is concluded that the model adequately describes the reaction system under the experimental conditions such that the ash layer diffusion is rate controlling.
Dynamics of moisture diffusion through a partially liquid filled porous matrix
Authors: Murty B. G. K. , Gidaspow Dimitri , Roy Dipak
Published: June 2004

Models for unsteady water transport in fuel cell configurations of Bacon‐Pratt and Whitney type are derived. Tests with a specially constructed isothermal cell producing no water and order of magnitude analysis show that diffusion through the liquid alone cannot account for the observed behavior. An analytical solution which includes diffusion in both the liquid and the gas spaces of the matrix is in better agreement with the data than models which consider diffusion in either the liquid or in the gas phase alone.
A new model for granular porous media: Part I. Model formulation
Authors: Payatakes Alkiviades C. , Tien Chi , Turian Raffi M.
Published: June 2004

A new model for porous media comprised of monosized, or nearly monosized grains, is developed. In applying this model to a packed bed, the bed is assumed to consist of a series of statistically identical unit bed elements each of which in turn consists of a number of unit cells connected in parallel. Each unit cell resembles a piece of constricted tube with dimensions which are random variables. The problem of flow through each unit cell is reduced, subject to reasonable assumptions, to the determination of the flow in an infinitely long periodically constricted tube. The solution of this flow problem is given in a companion publication. This model, together with the solution of the flow through it, can be used for the modeling of processes which take place in the void space of a bed.

As a preliminary test, theoretical friction factor values, based on the proposed model, were compared with experimental ones for two different beds and found to be in good agreement even in the region of high Reynolds numbers where the nonlinear inertia terms are significant.
Liquid densities and liquid enthalpies of hydrogen‐containing hydrocarbon mixtures
Authors: Chueh P. L. , Deal C. H.
Published: June 2004

Hydrogen, a quantum gas, raises to unique problemsin the estimation of liquid properties of mixtures containing dissolved hydrogen–a problem often encountered in hydroprocessing of hydrocarbons. The liquid density and enthalpy of a hydrogen‐containing mixture in particular are not adequately described by the pseudocritical concept but are best calculated by summing the liquid partial molar quantities of hydrogen and that of hydrogen‐free liquid solvent.

Liquid partial molar volumes and enthalpies of hydrogen have been evaluated and the results, including the effects of pressure and composition, presented in generalized equations. These generalized equations are shown to be useful in estimating the liquid density and enthalpy of hydrogen containing mixtures.
Liquid‐vapor equilibria at 112.00 K for systems containing nitrogen, argon, and methane
Authors: Miller R. C. , Kidnay A. J. , Hiza M. J.
Published: June 2004

Liquid‐vapor phase equilibria measurements were made at 112.00 K on the binary systems nitrogen‐argon, nitrogen‐methane, and argon‐methane and the ternary system nitrogen‐argon‐methane. Values of gE, the excess Gibbs free energy, have been calculated from the experimental data for all the systems studied. The data and derived gE values for the binary systems were compared with the results of previous investigations with satisfactory agreement.
A generalized hard‐sphere augmented virial equation of state
Authors: Bienkowski Paul R. , Denenholz Howard S. , Chao Kwang‐Chu
Published: June 2004

A generalized equation of state is developed by combinin a hard‐sphere equation with a truncated virial equation and generalizing the reduced hard‐sphere diameter as a function of reduced temperature and acentric factor. The new equation quantitatively agrees with Pitzer's table of compressibility factor over wide ranges of gas and vapor states and is always better than the truncated virial equation. Since the terms in the equation are physically meaningful it is capable of being improved systematically by including higher virial coefficients and by using hard‐core equations of state for nonspherical cores. The equation is extended to mixtures with well‐developed combination rules.
Holdup, flooding, and pressure drop in packed columns during countercurrent flow of mercury and water
Authors: Watson J. S. , McNeese L. E.
Published: June 2004

The hydrodynamics of countercurrent flow of liquids with a high density difference cannot be predicted reliably from correlations developed with data on fluids having low densities (usually water and organic solvents). Dispersed‐phase holdup, flooding rates, and pressure drop during countercurrent flow of mercury and water were studied with several packing materials. Results show that, for a given packing, flooding rates and holdup can be correlated in terms of a single parameter, the superficial slip velocity. For the mercury‐water system, this parameter is shown to be proportional to the packing diameter and packing void fraction for Raschig rings and solid cylindrical packing.
Stability of laminar pipe flows of drag reducing polymer solutions in the presence of high‐phase‐velocity disturbances
Authors: Hansen R. J.
Published: June 2004

A theoretical study of high‐phase‐velocity disturbances in the laminar pipe flow of drag‐reducing polymer solutions is reported. These disturbances are found to be more stable in a polymer solution with a sufficiently small relaxation time than in a Newtonian fluid. The opposite effect is predicted when the relaxation time exceeds a critical value, however. These results are shown to be consistent with a hydrodynamic instability explanation of the early turbulence phenomenon.
Permeation of gases in polystyrene molded at elevated pressures
Authors: Dale W. C. , Rogers C. E.
Published: June 2004

Atactic polystyrene was molded at pressures up to 3000 atmospheres, and the effects of this pressure history were studied by permeability measurements using helium, neon, and argon as probe molecules. The permeabilities were significantly reduced by molding at higher pressures. The diffusion coefficients decreased monotonically with molding pressure, reflecting more extensive interchain cohesion. In contrast, the solubility coefficients showed a broad minimum around a molding pressure of 1000 atm, indicating that changes in local order were induced by higher pressures. These changes were shown to affect permeation, mechanical characteristics, and other properties. An optimum molding pressure somewhat below 1000 atm is indicated for polystyrene.
Effect of specific gravity differences on nonideal mixing of continuous flow systems
Authors: Pelletier Martin P. , Cloutier Leonce
Published: June 2004

The effect of specific gravity differences as a primary factor of nonideal mixing was investigated and demonstrated by means of a combined M‐T (mixed‐tubular) reactor in a simple cylindrical flow tank. Specific gravity differences were provided by a temperature gradient created by a strongly exothermic, second‐order adiabatic chemical reaction. The results also allow investigation of the effects of the inlet feed rate, agitator diameter, and speed on the agitator fraction of the combined reactor.
Dynamic response of some ion‐selective electrodes
Authors: Markovic Patrick L. , Osburn James O.
Published: June 2004

The dynamic responses of five electrodes were measured by pulse testing. The electrodes were three pH electrodes a calcium‐ion electrode, and a chloride‐ion electrode. Measurements were made at temperatures from 1° to 50°C. The responses of their electrodes were analyzed to give the transfer function containing first‐ and second‐order time constants and a dead time.
Calculation of temperature distribution in the human body
Authors: Huckaba Charles E. , Hansen Lynn W. , Downey John A. , Darling Robert C.
Published: June 2004

An improved procedure is presented for the calculation of detailed steady‐state temperature distributions throughout the human body. The efficacy of the proposed computation procedure is demonstrated by comparison of calculated and experimental results for seven studies conducted on four subjects. Core temperatures were predicted within ±0.2°C and deviations for individual skin temperatures generally were within ±0.5°C.
Photopolymerization of acrylamide in an annular flow reactor
Authors: Sandru Dan , Smith J. M.
Published: June 2004

Rates of homogeneous polymerization of aqueous solutions of acrylamide were measured in an annular flow reactor at 35°C. By independent determinations of the quantum yield for the initiation step and the light intensity, it was possible to identify reaction orders and to calculate ratios of rate constants for the polymerization process.

An empirical kinetics model, based upon producing activated molecules solely from initiator (K2S2O8), best fit the data. According to this model the rate is 3/2 order in monomer concentration, 1/2 order in initiator, and proportional to the 1/2 power of the intensity of absorbed radiation. The effect of monomer concentration on the induction period and tlie 3/2 order with respect to monomer indicate a complex initiation process.
Cubic equations of state
Authors: Abbott Michael M.
Published: June 2004

Limitations and capabilities of a generic cubic equation of state are analyzed in light of observed real‐fluid behavior, and criteria are presented for classification of specializations of the generic equation. An example is worked out which illustrates the application of these criteria to the development of new equations of state.
Particle size analysis and structure of chromium hydrous oxide sols in the size range of less than 0.5 μm
Authors: Larson R. I. , Fullam E. F. , Lindsay A. D. , Matijevic E.
Published: June 2004

Particle size measurements of chromium hydrous oxide sols using electron microscopy and light scattering techniques were in excellent agreement. Comparison was based on the most probable diameter and width of the distribution. The normal, lognormal, and zero‐order logarithmic density functions provided good first‐order approximations to the particle size measurements. The chromium hydrous sols were less than 0.5 μm in size.

A closed wet cell specimen holder in an electron microscope was developed to observe, in situ, the chromium hydrous oxide sols. The colloidal particles had a uniform spherical shape with a narrow size distribution. Observation of the particle formation process in the closed wet cell qualitatively supports the mechanism that basic polymeric sulfates act as embryos in the formation of these particles.
Liquid ion‐exchange membranes
Authors: Moore J. H. , Schechter R. S.
Published: June 2004

A liquid membrane consisting of an oil layer contained between two aqueous phases was found to leak when used to transport ions selectively from one adjacent phase to another. The source of the difficulty was found to be the formation of a separate aqueous phase within the oil layer. This phase could be eliminated by increasing the pressure within the oil layer.

The pressure stabilized membrane was then tested and the observed rates of mass and electrical transport compared with values computed using a mathematical model. The comparisons were satisfactory considering the fact that no adjustable parameters were used to fit the data.
Thermodynamic properties of supercritical fluids and their mixtures at very high pressures
Authors: Breedveld Gerrit J. F. , Prausnitz John M.
Published: June 2004

Experimental and estimated PVT data for simple fluids at very high pressures have been correlated with corresponding states theory. Generalized tables and charts are given for density, enthalpy, fugacity, and internal energy for the reduced temperature range 1 to 50 and for reduced pressures to 2000. Consideration is given to possible solidification at very high pressures and to applicability of the reduced charts to quantum fluids, water and ammonia, through temperature‐dependent effective critical constants. The van der Waals two‐fluid model of binary mixtures is used to calculated properties of mixtures including the composition of coexisting phases. The correlations presented here are useful for estimating thermodynamic properties at very high pressures.
Theoretical interpretation of gas oil selectivity data on X‐sieve catalyst
Authors: Pachovsky Roman A. , John Thomas M. , Wojciechowski Bohdan W.
Published: June 2004

A six‐parameter multiresponse model based on the catalyst aging theory of Wojciechowski (1968) is applied to experimental selectivity data in gas oil cracking. Within the range of conditions studied, the model gave an adequate fit to the data. It was found that the selectivity curves at various cat/oil ratios were contained within optimum and minimum performance envelopes but that the relationships between these envelopes and the selectivity curves were not quite as simple as had previously been reported for a theoretical example (Campbell and Wojciechowski, 1969). The optimum time‐on‐stream for each of the cat/oil ratios was about one minute. Maximum gasoline production was 59 weight % at 81 weight % total cumulative conversion, resulting in a gasoline efficiency of 72.8%.
Simulataneous heat and mass transfer with and without reactant exhaustion in catalyst particles for reaction with volume change
Authors: Lih Marshall M. , Lin Kan
Published: June 2004

Asymptotic analytic expressions for the concentration and temperature profiles as well as effectiveness factor inside porous, thin‐disk shaped catalyst particles have been developed for zeroth‐order exothermic reaction with reactant‐to‐product volume change. The individual and combinative effects of volume‐change, Thiele and thermal Thiele moduli, and of the dimensionless activation energy are discussed. As expected, the expressions revert to those for the corresponding isothermal and constant‐volume cases. Errors arising from the approximation were calculated and found to be quite acceptable.
Liquid diffusion of nonelectrolytes: Part I
Authors: Ghai R. K. , Ertl H. , Dullien F. A. L.
Published: June 2004

This review covers the field of liquid diffusion form the time of the publication of the review article by Johnson and Babb in 1957. In Part I a concise introduction is given to the phenomenological description of the diffusion process, followed by a review of the various theories of and model approaches to diffusion in binary mixtures. These are treated in the following categories: hydrodynamic theories, Eyring's theory and the friction coefficient theories. The predictions are compared with the experimental results throughout the review. Part I will be followed by Part II in November reviewing self‐diffusion, empirical predictive equations, and experimental techniques. A supplement of critical tabulations of all experimental diffusion data since 1956 has been prepared.
Absorption in packed towers with concurrent downward high‐velocity flows—II: Mass transfer
Authors: Gianetto A. , Specchia V. , Baldi G.
Published: June 2004

Measurements were made of mass transfer coefficients with gas and liquid phase controlling resistance using a concurrent flow packed column with a wide range of operating conditions and four types of packing.

Mass transfer coefficients were much larger than those obtainable in countercurrent towers.

The results were correlated with dissipated energy values. The correlations obtained can be used to determine absorption efficiency. Experimental results show that the use of a high velocity concurrent flow column is particularly suitable when mass transfer is controlled by the liquid phase resistance with chemical reaction in the liquid.
Mass transfer to a plane below a rotating disk at high Schmidt numbers
Authors: Homsy Robert V. , Newman John
Published: June 2004

The Lighthill transformation is used to determine the rate of mass transfer at high Schmidt numbers to a disk imbedded in a stationary plane below a rotating disk. This diffusion‐layer solution breaks down near the center and leading edge of the mass‐transfer disk. Solutions in these regions are reported, and a uniformly valid composite solution for the local Nusselt number is determined along with an expression for the average mass‐transfer rate to the disk.
A new technique for precedence‐ordering chemical process equation sets
Authors: Soylemez Sezer , Seider Warren D.
Published: June 2004

An algorithm that combines structural equation analysis with algebraic rearrangement and substitution has been developed to precedence‐order algebraic chemical process equations. The SWS (Structural Analysis with Substitutions) algorithm selects an output variable for each equation, rearranges the equation to solve for that variable, and reduces the number of equations by substitution. The algorithm has been used for computer generation of Fortran programs to perform meterial and energy balances in the design of chemical processes.
Computational models for cylindrical catalyst particles
Authors: Sorensen Jan P. , Guertin Earl W. , Stewart Warren E.
Published: June 2004

A study is made of computational methods for predicting the performance of cylindrical catalyst particles in reactions with nonlinear kinetics. Accurate two‐dimensional collocation solutions are obtained and used to test simplified solution methods. A novel parametric integration method is used to traverse the region of multiple solutions. The local stability of several states is determined.
Motion of particles entrained in a plasma jet
Authors: Lewis J. A. , Gauvin W. H.
Published: June 2004

The motion of small particles (glass microspheres, 30 to 140 microns in diameter) entrained in a free argon plasma jet was studied by means of high‐speed cine streak photography. Radial temperature and velocity profiles as well as axial profiles of temperature, velocity, and argon concentration in the jet were experimentally determined by means of a plasma calorimetric probe. The system was found to be characterized by low relative Reynolds numbers (0.2 to 20) and extremely high deceleration rates (about –2,000 g). Under these conditions, an increase of drag coefficient over that predicted by the standard curve was experimentally observed. This increase was attributed to the nonsteady flow field around the particle (the so‐called “history term” in the equation of motion). A general computer program has been proposed which predicts the particle velocity, acceleration and temperature along its trajectory.
Kinetics of liquid phase xylene isomerization over H‐mordenite
Authors: Hopper J. R. , Shigemura Dennis S.
Published: June 2004

A study of the kinetics for the liquid phase isomerization of ortho‐xylene over H‐mordenite has been made at 505°K, 2.76 × 105 N/m2, and 23 mole % toluene diluent. This is the first known study reporting kinetic data for the liquid phase isomerization of xylene over a zeolite catalyst. High activity is indicated by the 80% achievement of para‐xylene equilibrium at 505°K, 2.76 × 105 N/m2, and 0.767 × 10−3 kg/s/kg. Although high selectivity has previously been reported for a specifically prepared zeolite catalyst, the 99+% selectivity of the isomerization reaction with H‐mordenite as indicated by no C9+ aromatics and less than 0.5 mole % benzene in the product is most significant. Catalyst deactivation was also significant. Reaction rate constants are reported for a first‐order reversible triangular model among the xylene isomers with catalyst deactivation incorporated into the model.
Crystal‐size distribution and its interaction with crystallizer design
Authors: Moyers Charles G. , Randolph Alan D.
Published: June 2004

Recent progress in understanding crystallization processes is reviewed, especially with regard to the problem of crystal‐size distribution (CSD) and its many interactions with the design, analysis, and operation of crystalizers. This subject is considered from both the researcher's and practitioner's points of view, and special attention is given to the impact of recent theories on crystallizer design and operation.

A generalized theory for the analysis and prediction of CSD, based on population balance mechanics, has been developed and tested over the past decade. Predictive design of CSD is now a possibility with the design techniques presented here and using suitable bench‐scale data. Published evaluations of the reliability of design methods utilized in commercial practice would be a valuable asset to the science of crystallization.
A liquid thermistor
Authors: Cussler E. L.
Published: June 2004

A liquid thermistor consisting of a salt‐triethylamine‐water solution shows a resistance increase of 100% per degree centigrade over a range of 8°C. Outside this specific temperature range, the resistance changes slowly. The altered resistance results from the phase change at the critical solution temperature. While devices of this type can show major hysteresis and are restricted to specific temperatures, their response is faster than a millisecond.
Effects of diffusion resistance on gasoline selectivity in catalytic cracking
Authors: Pachovsky Roman A. , Wojciechowski Bohdan W.
Published: June 2004

The time on stream theory of catalyst decay is applied to gas oil cracking selectivity data from a static bed reactor operating with a diffusion limited catalyst. It is found that intraparticle diffusion affects the reactions leading to the disappearance of gas oil to a much greater extent than the reaction leading to the recracking of gasoline and catalyst poisoning. Reasons for this behavior are postulated. It is also found that the overall kinetic order for the rate of disappearance of gas oil is decreased with the result that maximum selectivity occurs at a higher conversion value than for a corresponding diffusion‐free catalyst. It is concluded that probably diffusion limitation is not a serious problem with respect to gasoline selectivity in commercial reactors.
Stability of the class II classified product crystallizer with fines removal
Authors: Randolph Alan D. , Beer Gary L. , Keener James P.
Published: June 2004

The stability of crystal‐size distribution (CSD) in the classified product crystallizer with fines removal was investigated using spectral techniques to determine stable solutions of the linearized population balance. The model used to describe the crystallizer assumed rapid growth kinetics (high yield), magma‐dependent secondary nucleation, and recycle of dissolved fines. Fines removal and classified product removal were characterized in the model by piece‐wise constant removal rates (R – 1) and z times the MSMPR removal rate, respectively.

Stability regions were presented as critical values of the kinetic nucleation/growth rate exponent i = d(log B°)/d(log G) versus dimensionless parameters of the system. The parameters which influence CSD stability were maximum fines size and removal rate, product classification size and removal rate, and the magama‐characterizing exponent in the nucleation expression. Whether or not dissolved fines are recycled directly back to the crystal magma also influences stability.
Water jet atomization of molten steel
Authors: Grandzol Richard J. , Tallmadge John A.
Published: June 2004

Data are obtained and a model derived for describing particle size distribution for molten metals atomized by two water jets. The influences of water jet parameters on size distribution and median size are reported and discussed in terms of fundamental quantities and model predictions. The data, which were obtained using fan‐spray jets impinging at an apex angle of 60° to atomize Type 4620 steel, indicated that median size was primarly a function of water jet velocity.
Spatial formulation of the Orr‐Sommerfeld equation for thin liquid films flowing down a plane
Authors: Krantz William B. , Owens W. Brechner
Published: June 2004

The linear stability problem for thin liquid films flowing down a plane is formulated in terms of disturbance which are harmonic in space and time and grow or decay spatially. A closed‐form analytical solution to the resulting spatial formulation of the Orr‐Sommerfeld equation is shown to compare more favorable with wave property data than do solutions to the classical temporal formulation of this stability problem. The predictions of Gaster that the spatial and temporal formulations will be equivalent only for weakly amplified nondispersive disturbances are confirmed for falling film flow.
Dissolution of a homogeneous porous medium by surface reaction
Authors: Glover Martin C. , Guin James A.
Published: June 2004

In this paper a mathematical model is used to predict the time behavior of porosity and permeability of a porous medium being dissolved by acid. Experimentally determined reaction kinetics and pore size distribution are used in the model. The acidizing process studied here is of importance in the stimulation of oil well reservoirs. A polynomial expansion method is used to obtain an approximate solution to an infinite hierarchy of moment equations resulting from application of the capillary model. Experimental porosity and permeability measurements using a sintered glass disk dissolved by hydrofluoric acid are in good agreement with predictions from the model.
Reaction path synthesis strategies
Authors: Powers Gary J. , Jones Russell L.
Published: June 2004

A system is offered for the mathematical representation of the functional and structural features of organic molecules and their reactions. Two basic synthesis strategies, an antithetic method anda synthetic method, are defined and compared. The use of heuristic information in guiding synthesis is evaluated. A synthetic method which uses dynamic programming is presented and applied to the synthesis of bihelical DNA. Possible extensions to other classes of compounds are presented.
Molecular thermodynamics for chemical reaction design
Authors: Eckert C. A. , Hsieh C. K. , McCabe J. R.
Published: June 2004

Various techniques of molecular thermodynamics and solution theory have been applied, through the transition state theory, to problems in chemical kinetics. These include experimental techniques for ascertaining the structure and properties of the transition states for various classes of reactions, plus analytical methods for using this information to predict the effect of solvents or reactant structure on chemical reaction rates. Such methods provide the chemical engineer with an additional parameter to use in the optimal design of reaction systems–that is, the chemistry of the reaction itself.
Oscillating behavior on distillation trays
Authors: Biddulph Michael W. , Stephens David J.
Published: June 2004

The objective of this work was to study the undesirable oscillating behavior which can develop on distillation trays. This takes the form of violent lateral movements of the gas/liquid mixture, causing premature flooding and reduced efficiency. It has been demonstrated that entrainment is significantly increased by the presence of oscillations. A simple predictive method by which a designer may evaluate the likelihood of oscillations occurring is proposed. It is concluded that columns of greater than about 1.0 m diam. operating at atmospheric pressure or above are unlikely to oscillate. However, reduced pressure columns of greater diameter may oscillate. A very simple mesh baffle system which completely prevents oscillations developing is described.
Analysis of the normal stress extruder
Authors: Good Paul A. , Schwartz Arthur J. , Macosko Christopher W.
Published: June 2004

A theoretical and experimental investigation of the pumping characteristics of the normal stress extruder was made. The theoretical model requires only material property data and extruder dimensions and rotation speed to evaluate the main velocity field, flow rate, and pressure. The flow from the extruder was measured for two viscoelastic polymer solutions and a polymer melt as a function of gap setting and angular velocity. These measurements were in reasonable agreement with the proposed model.
Chlorination of sulfur dioxide in a plasma arc photochemical reactor: Part I. Reactor performance
Authors: Quarderer George J. , Kadlec Robert H.
Published: June 2004

This is a study of a photochemical reactor consisting of a vortex‐stabilized arc and an annular, triple‐walled, fused silica reaction chamber. An argon arc plasma provides the light. For power inputs of 3‐12 kw, the spectral output of the light source was characterized as a function of wavelength, arc‐gas flow rate, power input to the arc, and position along the arc. For power inputs of 3.84 and 8.45 kw, there were, respectively, 0.314 and 0.862 einsteins emitted per hour in the 2500 to 5000Å wavelength region. Selective filter solutions of 1.5N KNO3 and 0.05N KI were investigated. A reactor analysis is presented, based on mass and energy balances, and the geometrical properties of the system.
Chlorination of sulfur dioxide in a plasma arc photochemical reactor: Part II. Chlorination of sulfur dioxide
Authors: Quarderer George J. , Kadlec Robert H.
Published: June 2004

The photochemical chlorination of sulfur dioxide was investigated experimentally. The photochemical reactor was the vortex‐stabilized arc radiation source described in Part I. Aqueous inorganic solutions, providing selective wavelength filtration, were circulated through the inner annular region. The outer annulus served as the reaction volume. The dependence of the reaction on wavelength, reaction gas inlet temperature, pressure, and reactant flow rate was investigated. The amount of sulfur dioxide in the mixture was varied from 1/6 to 2/3 atmosphere. The photochemical rate of formation of sulfuryl chloride is best described by the rate expression:

where J is the volumetric rate of light absorption and where k0 and E have values of 0.0542 s1/2 and −2.6 kcal/gmol, respectively.
Developing pressure profiles for non‐Newtonian flow in an annular duct
Authors: Bhattacharyya Satinath , Tiu Carlos
Published: June 2004

A steady, laminar, isothermal flow of non‐Newtonian fluids in the entrance region of an annulus has been studied experimentally. The axial pressure distributions, as well as the excess pressure energy, in the developing flow region are presented. The loss coefficients are found to increase with increasing flow behavior index for inelastic power law fluids. The experimental values of the loss coefficients are about 20% lower than those predicted from the boundary‐layer approximation method presented earlier. A preliminary result indicates that the entrance loss for a viscoelastic fluid is much smaller than that for the inelastic fluid of the same flow behavior index.
Theoretical development and experimental verification of a novel, well‐mixed vessel
Authors: Landau Julian I. , Petersen Eugene E.
Published: June 2004

The mixing characteristics of a vessel containing no moving parts have been studied theroretically and experimentally. The vessel consists of two chambers separated by a porous barrier. Mixing results because elements of fluid permeating the barrier at various distances from the inlet reside for different periods of time within the vessel and combine with other elements having entered earlier and later. An apparatus was designed a priori and experimentally verfied to give a residence‐time distribution function the same as a completely mixed vessel. The method was extended to show that in principle a vessel exhibiting any residence‐time distribution function can be designed by modifying the geometries of the chambers and the porous barrier.
Determination of slip ratios in air‐water two‐phase critical flow at high quality levels utilizing holographic techniques
Authors: Lee Young J. , Fourney Michael E. , Moulton Ralph W.
Published: June 2004

Holographic techniques employing a pulse ruby laser were used to measure the size and velocity of drops for air‐water two‐phase critical flow at quality levels above 0.95. The use of a large numerical aperture in the holographic recording system permitted diffraction limited resolution of the droplets. The measured slip ratio a long withthe observation that a very significant portion of the liquid phase was concentrated near the boundary layer at the exit plane indicates that a separated flow model describing two‐phase critical flow would represent the actual conditions to a better degree than the other models.
A calculational procedure for design problems in multicomponent distillation
Authors: Ricker Neil L. , Grens Edward A.
Published: June 2004

A calculation procedure for multicomponent distillation has been developed that is directly applicable to design problems. It is based on successive approximation methods with adjustment of the number of equilibrium stages in each column section between iterations to meet given reflux flow and feed stage composition conditions while maintaining specified key component recoveries. This procedure has been applied to a number of representative distillation design problems. It converges readily to proper column designs from initial estimates based on a noniterative stage‐to‐stage calculation. Moreover, the procedure is markedly superior in computational efficiency to solution of design problems by repeated application of operating calculations to assumed column configurations.
A new method for the estimation of parameters in differential equations
Authors: Bosch Bruno Van Den , Hellinckx Leon
Published: June 2004

A new objective function for estimating parameters in differential equations, based upon a weighted least squares criterion for the residuals of these equations, is presented. The use of Lobatto quadrature in combination with the collocation technique reduces the original problem to one of minimizing a simple algebraic expression with respect to a series of unknowns. The method can be applied to different types of differential equations as shwon by a series of examples and leads to very good estimates. It becomes particularly useful for systems which are linear in the parameters and for which all states are observable since in this case the usual convergence problem is avoided. The gain in computation time when compared with classical methods is significant.
Simultaneous measurement of interfacial area and mass transfer coefficients for a well—mixed gas dispersion in aqueous electrolyte solutions
Authors: Robinson Campbell W. , Wilke Charles R.
Published: June 2004

A new measuring technique involving concurrent chemical absorption of carbon dioxide and desorption of oxygen is developed for simultaneously evaluating the liquid‐phase mass transfer coefficient kL and the specific area a of sparingly‐soluble gas dispersions in stirred tanks containing an aqueous solution of inorganic electrolytes. The method ensures that kL and a are evaluated under consistent hydrodynamic conditions.

Results from three different nonviscous systems show that at high agitation power, such that the average bubble diameter is between 0.2 and 2 mm, kL decreases with increasing power input and is dependent on the bubble diameter. This behavior is in contrast to the results of others at lower agitation levels or in nonelectrolytic liquids, but in general agreement with previous results for bubbles of the same diameter range produced in viscous, nonelectrolytic solutions.
Computer‐aided safety interlock systems
Authors: Rivas J. Roberto , Rudd Dale F. , Kelly Lloyd R.
Published: June 2004

Since operation error is a major factor contributing to industrial disaster, it is necessary to develop safety interlock systems which prevent modes of operation that are known to be dangerous. It is not possible to foresee all the disruptions that might occur and, for this reason, an a priori analysis of safety problems is incomplete. At each step in operation the state of the process must be updated if hazardous conditions are to be avoided. To a large extent this is a problem in logic which can be handled rapidly by the computer using the methods developed here.
Synthesis of failure‐safe operations
Authors: Rivas J. Roberto , Rudd Dale F.
Published: June 2004

Methods are developed for the computer‐aided synthesis of sequences of valve operations to reach complex operation goals with safety. Given dangerous events which must not occur and operation goals to be reached, sequences of valve openings and closings are formed rapidly for industrially significant problems.
Measurement and prediction of high‐pressure phase equilibria with a dilute component in the gas phase: The methane‐n‐hexane system
Authors: Gunn Robert D. , McKetta John J. , Ata Nassar
Published: June 2004

The design of vapor recovery processes requires very accurate vapor‐liquid equilibria data. In this work the problem is attacked from both an experimental and a correlational viewpoint, and the methane‐n‐hexane system is chosen for study. A predictive model for vapor‐liquid equilibrium aids in the interpretation of the experimental measurements, and data acquired in this study agree closely with the theoretical predictions. Maximum deviation between calculated and experimental equilibrium ratios (yi/xi) is 8.5% with average absolute deviations of 3% for n‐hexane and 0.1% for methane. Several procedures are described for checking the accuracy of experimental VLE data when a heavy vapor is present at low concentrations in the gas phase. Several potential sources of experimental error are also identified and discussed.
Fast fluxes with supercritical solvents
Authors: Rance Robert W. , Cussler E. L.
Published: June 2004

Measurements of iodine dissolution rates in supercritical carbon dioxide and other supercritical fluids show when the iodine flux in these systems can be made fast. For these systems, the dominant factor in achieving this fast flux is the solubility; increases in diffusion coefficient have less effect. An approximate guide for estimating these fluxes is developed and compared with the experimental results.
Concentration profiles in free‐flow electrophoresis
Authors: Reis Joaquim F. G. , Lightfoot E. N. , Lee Ho‐Lun
Published: June 2004

An analysis is presented which enables detailed description of solute concentration profiles for free‐flow elecrophoresis in planar slit flows. This analysis is suitable for either batch or continuous operation with arbitrary variation of solute input rate, and it requires no seriously restrictive assumptions other than constancy of equilibrium and transport properties. It permits for the first time a systematic investigation of the effects of governing parameters and can be used to optimize operating conditions. The most significant finding is that Taylor dispersion, ignored in previous analyses, markedly reduces separability.
An effective numerical integration method for typical stiff systems
Authors: Aiken Richard C. , Lapidus Leon
Published: June 2004

There is an equivalence between stiff and singularly perturbed systems of ordinary differential equations. This feature is exploited in this paper by numerically employing recent singular perturbation methods to attack troublesome boundary layer stage of the solution in which some variables have very short response times. The numerical method affords a means of essentially determining the thickness of this boundary layer. The algorithm is capable of high stability and accuracy for the commonly occurring stiff system, whether or not it is in singularly perturbed form. Application to a singularly perturbed reaction system and a highly stiff reactor system not in singularly perturbed form demonstrate the effectiveness and utility of this approach.
Unsteady mass transfer in a long composite cylinder with interfacial resistances
Authors: Stevenson James F.
Published: June 2004

A solution is given for unsteady state concentration profiles in an infinitely long composite cylinder resulting from a step‐change in concentration in a large reservoir surrounding the cylinder. The composite cylinder consists of an inner cylinder with diffusivity D1 surrounded by a permeable tube with diffusivity D2 and has interfacial mass transfer resistances at the cylinder‐tube and tube‐reservoir interfaces. Numerical values are given for the first eight roots and various coefficients of the solution for physical properties typical of tubular (hollow fiber) membranes. These results can be used in the analysis of data from unsteady state mass transfer experiments to determine the permeability of homogeneous tubular membranes. A simple, approximate method for data analysis is suggested for the rapid estimation of the permeability of both homogeneous and asymmetric (skinned) tubular membranes.