bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamic consistency tests for solid‐liquid equilibria
Authors: Null Harold R. 
Published: June 2004

AbstractThe technique of testing the validity of phase equilibria by applying thermodynamic consistency tests is highly developed for vapor‐liquid equilibria. The application to solid‐liquid equilibria, howerver, has been developed very little. The problems associated with thermodynamic consistency tests are discussed and a new technique for evaluating the validity of experimental data has been developed. Several possible test equations are presented and are applied to test the consistency of three sets of solid‐liquid equilibrium data.
Motion of gas bubbles in non‐Newtonian liquids
Authors: Astarita Gianni , Apuzzo Gennaro 
Published: June 2004

AbstractThe available theoretical knowledge of the motion of gas bubbles in Newtonian liquids is reviewed, and the possibility of extension to non‐Newtonian liquids, both purely viscous and viscoelastic, is studied. Experimental data on the rising velocities of gas bubbles in a variety of non‐Newtonian liquids are presented and interpreted on the basis of theoretical knowledge. Peculiarities that have been observed in highly elastic liquids are discussed, and a tentative interpretation is offered.
Isothermal activity coefficients for the system cyclohexane—n‐heptane—toluene at 25°C
Authors: Katayama Takashi , Sung Edmond K. , Lightfoot Edwin N. 
Published: June 2004

AbstractIsothermal vapor‐liquid equilibrium data at 25°C are presented for the ternary and binary system containing cyclohexane, n‐heptane, and toluene. These data were obtained by static equilibration in the presence of diluent nitrogen by chromatographic analysis of the saturated vapor. The data obtained were of at least comparable accuracy to those available at the normal boiling point, and the procedure appears to offer several substantial advantages. Neither a priori prediction of activity coefficients from regular solution theory nor extrapolation of data taken at the normal boiling point is a satisfactory substitute for the isothermal data.
Sedimentation of dilute suspensions in creeping motion
Authors: Famularo Jack , Happel John 
Published: June 2004

AbstractSolutions to the creeping motion equations for a cylinder and particles in an infinite media were superimposed to calculate the first‐order correction to the Stokes settling velocity for a particle inside a cylindrical container and for various models used to approximate the settling characteristics of dilute suspensions. The models were based on an assumed disribution of translating particles subject only to the hydrodynamic forces produced by their motion. Particle interactions and wall effects for ordered and random arrangements of spherical particles in a cylinder were calculated on a digital computer and used to devlop equations for settling velocity as a function of concentration.The equations developed for the models containing spherical particles were modified to apply to nonspherical particles by considering each particle as a point force with regard to the fluid motion it produces at neighboring particles. As an application of these equations, a model of a dilute fiber suspension was studied in which prolate spheroide settle perpendicular to their symmetry axes.The correction to Stokes' law for ordered arrangements of spheres is close to that obtained by earlier investigators working with similar models. However this correction leads to lower settling rates than the bulk of reported experimental data at any given particle concentration in the dilute range of less than 5% solids. The authors have shown that this discrepancy may be eliminated by assuming an alternate model composed of doublets in place of uniformly distributed particles. It may be concluded that in the dilute concentration range a model of a sedimenting suspension must include terms which reflect its tendency toward cluster formation and the consequent effect on settling rate. In order to accomplish this, forces other than hydrodynamic may have to be considered, for example, electrostatic forces.
Direct contact heat transfer with change of phase: Condensation of single vapor bubbles in an immiscible liquid medium. Preliminary studies
Authors: Sideman Samuel , Hirsch Gideon 
Published: June 2004

AbstractMotion picture studies of condensation of isopentane bubbles rising in water elucidate the transfer mechanism involved in latent heat transport.In general, two characteristic regions are noted. In the first region, up to some 80% liquid content, the bubbles deform and oscillate and heat is transferred by turbulent convection. In the second region the rate of transfer is controlled by the resistance of the condensed liquid, and heat is mainly by conduction. The effect of temperature differences between the bubble and the continuous phase (up to 3.5°C.) on the transfer coefficients could not be isolated, whereas that of the initial diameter of the bubble was quite marked.The results are in agreement with those obtained in earlier studies of evaporating drops in immiscible liquids, indicating the similarity of the basic heat transfer mechanisms.
Heat transfer to evaporating refrigerants in two‐phase flow
Authors: Lavin J. Gerard , Young Edwin H. 
Published: June 2004

AbstractFlow regimes occurring during evaporation of Freon‐12 (dichlorodifluoromethane) and Freon‐22 (monochlorodifluoromethane) inside five tubes were investigated. Two flow models are proposed, one each for vertical and horizontal tube orientation. The limits of each flow regime were determined and heat transfer correlations obtained. The most significant flow regimes were found to be nucleate boiling, annular flow, and mist flow. A correlation for the transition between annular flow and mist flow was obtained.
A two‐way capillary viscometer
Authors: Tzentis L. S. 
Published: June 2004

AbstractA two‐way capillary viscometer for measuring shear rates from <0.01 to >1,000,000 sec.−1 at pressure drops up to 1,000 lb./sq.in. has been designed. It consists of a capillary tube mounted vertically between two sample reservoirs, of which the lower one is connected to a mercury manometer. The driving force, gas under pressure in a large tank, is connected to the upper reservoir and the manometer, thus allowing the sample to be moved in either direction through the capillary. The special feature of this viscometer is the indirect automatic measurement of bulk velocity of the fluid sample (3 to 20 cc.) in the capillary tube by means of a mercury manometer.The precision of measurement of the velocity is one part in four hundred and can be maintained over the whole range of shear rates by the appropriate choice of the ratio of the diameter of the capillary and manometer tube.Energy losses due to capillary heating and kinetic energy are given in terms of ΔP across the capillary. Couette end effect was found to be 0.3 diam.A study of the rheology of polyacrylonitrile (PAN) in concentration range of ½ to 10½% PAN shows that the non‐Newtonian behavior and elasticity of PAN solution increases rapidly with concentration.
Heat transfer and reaction in laminar tube flow
Authors: Rothenberg R. I. , Smith J. M. 
Published: June 2004

AbstractAn analytical study was made of the temperature and composition distribution and heat transfer characteristics for a reacting fluid in a tube. The reaction was assumed to be first order and irreversible and the flow to be laminar.The results, which consisted of radial and axial profiles of temperature, composition, and Nusselt number could be expressed in terms of four parameters. The gradient of radial composition was usually sufficient to judge the effect of reaction on the heat transfer coefficient. Owing to residence time and temperature effects, the Nusselt number even for an exothermic reaction was usually greater than that for an inert system. For endothermic cases, the energy flux due to diffusion increases the total energy flow, and the Nusselt number may be several fold that in the corresponding nonreactive system.For certain values of the parameters the radial temperature and composition profiles showed maxima and minima between the wall and center of the tube. At these conditions the direction of the flow of energy due to diffusion could not explain the increase in Nusselt number.
Why thermodynamics is a logical consequence of information theory
Authors: Tribus Myron , Shannon Paul T. , Evans Robert B. 
Published: June 2004

AbstractAn observation of the properties of bulk matter necessarily omits many details of the motion of the particles which comprise that matter. If a communication regarding the observation is to be consistent, it must conform to certain rules which follow from the theory of information. An analysis of the problem of deciding upon a consistent encoding for such observations leads, as a unique result, to the concepts and equations of classical thermodynamics. The information‐theory analysis of this problem also leads to a better understanding of the basis for the “laws” of thermodynamics.
Height of a liquid film in a horizontal concurrent gas‐liquid flow
Authors: Cohen Leonard S. , Hanratty Thomas J. 
Published: June 2004

AbstractResults of a study of the height of liquid films flowing concurrently with an air stream in a horizontal channel are presented. If three‐dimensional waves exist at the interface, the dimensionless film height h+ = hu*/v, defined in terms of the friction velocity and the kinematic viscosity of the liquid, is primarily a function of the liquid Reynolds number.
Vapor‐liquid phase behavior of the helium‐methane system
Authors: Sinor J. E. , Schindler D. L. , Kurata Fred 
Published: June 2004

AbstractThis report presents more extensive experimental vapor‐liquid equilibria data for the helium methane system than are found in the literature. A static sampling technique was used to obtain vapor and liquid compositions for six temperatures between −180° and −85°C. and pressures up to 2,000 lb./sq.in.abs. Data at 2,000 lb./sq.in.abs. were extended to the critical temperature of the mixture.Average scatter of the data from the smoothed lines is approximately 1% of the helium concentration or 0.03 mole % helium, whichever is larger. Vapor compositions at −140°, −160°, and −180°C. were analyzed by a different technique and scattered on the average from the smoothed curve less than 4% of the methane concentration. Comparisons are drawn between the data of this study and the previously published work of Kharakhorin. The solubility of helium in liquid methane was found to be considerably less than the values indicated by Kharakhorin.Experimental data are presented in tabular form and in various phase composition diagrams. The behavior of the helium‐methane system is seen to be very similar to that of the helium‐nitrogen system, with helium being much less soluble in methane than in nitrogen.The data were satisfactorily represented by means of the Krichevsky‐Kazarnovsky equation. Extrapolations to higher pressures should be feasible.
The application of the Geddes fractionation index to crude distillation units
Authors: Gilbert R. J. H. , Leather J. , Ellis J. F. G. 
Published: June 2004

AbstractThe degree of separation effected by a fractionator can be measured by a fractionation index n. The index is the equivalent number of theoretical plates, operating at total reflux, which would effect the same component separation as the fractionator.The value of the fractionation index is readily calculated from the Fenske‐Underwood equation when component analyses of the feed and products are available.In the case of crude oils, the number of components is so great that resolution in the laboratory is not practicable, and the feed and products are customarily analyzed by high efficiency laboratory fractionators which give their true boiling point characteristics. In this form, the data have been broken down into short fractions which have then been treated as pseudo components in subsequent column calculations.This paper presents a method for treating the product TBP curves as algebraic functions without the necessity for breaking the feed TBP data into arbitrary short fractions. The fractionation index can be derived directly from product TBP data, or the TBP data can be calculated when the fractionation index is known.Data from performance tests on three commercial units have been analyzed. The TBP distillation analyses of the crude oils and the products enabled the fractionation indices pertaining to each section of the fractionators to be evaluated.
Axial mixing and extraction in a mechanically agitated liquid extraction tower
Authors: Bibaud Roger E. , Treybal Robert E. 
Published: June 2004

AbstractAxial mixing was measured in both phases for a countercurrently operated, mechanically agitated extractor of the Oldshue‐Rushton design for water continuous and toluene and kerosene dispersed. Results in terms of an eddy axial diffusivity were correlated in terms of the variables studied. These correlations were then applied to column performance during extraction of n‐butyl amine from kerosene into water, and the true mass transfer coefficients, corrected for axial mixing, were determined. These are shown to be predictable for droplets of dispersed phase considered to be rigid spheres.
Particle migration in shear fields
Authors: Denson C. D. , Christiansen E. B. , Salt D. L. 
Published: June 2004

AbstractThe motion of a single rigid sphere entrained in a glycerine‐water solution flowing downward through a cylindrical tube has been investigated throughout a range of particle Reynolds numbers of 6.0 to 120.0, tube Reynolds numbers of 208 to 890, and particle‐to‐tube diameter ratios of 0.120 to 0.190. Trajectories of the sphere, calculated for various particle Reynolds numbers by using the Rubinow‐Keller expression for the transverse force, were found to agree satisfactorily with experimentally determined trajectories when the particle Reynolds number was below 40.0. In all cases the sphere was observed to migrate to the axis of the tube. At the lower particle Reynolds numbers the sphere approached the axis asymptotically, whereas at the higher particle Reynolds numbers the sphere oscillated across the axis of the tube one or more times during migration. All observations were made with spheres which were less dense than the fluid, the density difference being as high as 10% of the fluid density.
Reduction of single particles and packed beds of hematite with carbon monoxide
Authors: Osman M. A. , Manning F. S. , Philbrook W. O. 
Published: June 2004

AbstractSintered spheres of reagent grade hematite and particles of vermilion ore were reduced by carbon monoxide‐carbon dioxide mixtures over the temperature range 820° to 920°C. If all the weight loss were assumed to occur at a single hematite‐iron interface, then the early stages of reduction could be correlated by a series combination of the individual resistances due to boundary‐layer transport, transport through the reduced iron shell, and interfacial chemical reaction. Sintering and cracking affected the reduction at later stages. Particle reducibility, measured as rate of weight loss, was independent of particle porosity.Packed beds of similar sized vermilion ore particles were reduced with carbon monoxide‐carbon dioxide mixtures at temperatures between 820° and 920°C. Barner's and Spitzer's methods of estimating fixed‐bed reduction rates and exit gas compositions were modified to include the multiple‐step, single‐particle kinetic models. The resulting predictions of fractional reduction agreed closely with the present data; however, theoretical and experimental exit gas compositions differed considerably.
Catalytic oxidation of hydrogen—intrapellet heat and mass transfer
Authors: Maymo J. A. , Smith J. M. 
Published: June 2004

AbstractRates of oxidation of hydrogen were measured by using platinum–alumina catalyst particles and 1.86‐cm. pellets. For high‐reaction rates, temperature differences between center and surface of the pellets were more than 300°C. Under these conditions large variations in temperature with position on the pellet surface were observed. The pellet reactor was of the recirculation, stirred‐tank type with injection nozzles. Local heat transfer coefficients between pellet and gas varied twofold with location on the surface. The data showed that intrapellet heat and mass transfer resistances were both important, while between pellet and gas only the heat transfer resistance was significant.The effective thermal conductivity of the pellet was measured independently. By using this and the experimental temperature measurements, a new method s devised to establish the effective diffusivity under reaction conditions.Effectiveness factors were predicted from ke and De and the rate data for the particles. The results were about 7% greater than the experimental effectivenes lactor.
Chemical reactions during rapid quenching of oxygen‐nitrogen mixtures from very high temperatures
Authors: Ammann P. R. , Timmins R. S. 
Published: June 2004

AbstractA model has been developed to study chemical reactions which occur in oxygen‐nitrogen mixtures during very rapid cooling in small‐diameter tubes. The system considers both homogeneous gas phase reactions and surface reactions based upon a simplified mass transfer mechanism. With an energy balance used to determine the rate of quenching, the mole fractions of nitrogen, oxygen, nitric oxide, atomic nitrogen, and atomic oxygen were calculated as a function of temperature. In these studies, air and an equimolal oxygen‐nitrogen mixture were cooled from temperatures which ranged between 3,000° and 7,000°K. The calculations showed that when the gases were cooled at rates exceeding ten million degrees per second, the species did not follow a chemical equilibrium path during the quenching process. In cooling from 4,000° to 7,000°K. the computations show that consideration of surface reactions predicts greater nitric oxide yields in the quenched gas than for homogeneous reactions alone. In fact, the heterogeneous reactions must contribute to the overall chemistry of quenching air. The composition of the quenched gas is strongly dependent upon the temperature‐time history of the gas in the probe and upon the composition of the hot gas before it is quenched.
Stresses in concentrated polymer solutions: Part I. Shear dependence of viscosity
Authors: Williams Michael C. 
Published: June 2004

AbstractA method is suggested for calculating stresses in sheared polymeric liquids. It synthesizes Kirkwood's correlation function techniques and Fixman's formulation for the stress tensor P. The dependence of P on powers of solute concentration, in the concentrated solution range, arises from a consideration of intermolecular forces. A non‐Newtonian viscosity, characterized by only two parameters (low shear viscosity limit ηo and time constant λ), is derived from simple choices of functions which appear in the expression for P.
Thermal conductivity of binary mixtures of carbon dioxide, nitrogen, and ethane at high pressures: Comparison with correlation and theory
Authors: Gilmore Thomas F. , Comings E. W. 
Published: June 2004

AbstractA secondary thermal conductivity cell of the horizontal, concentric cylinder type was developed. The thermal conductivity of the pure gases nitrogen and ethane and approximately 20, 40, 60, and 80% binary mixtures of carbon dioxide, nitrogen, and ethane were determined at 75°C. to 3,000 atm. Several predictive techniques were investigated and recommendations are made.
Effect of axial diffusion of vorticity on flow development in circular conduits: Part II. Analytical solution for low reynolds numbers
Authors: Vrentas J. S. , Duda J. L. 
Published: June 2004

AbstractAn analytical solution based on a previously proposed entrance model is developed for the case of flow at low Reynolds numbers. Agreement between this solution and the published numerical solution at this Reynolds number limit supports the authenticity of the numerical solutions presented previously.
Heat conduction with solidification in a stratified medium
Authors: Hrycak Peter 
Published: June 2004

AbstractWith the use of the heat balance integral method, a formula for the depth of solidification in a stratified medium is derived that applies to Newton's cooling at the surface, where the temperature of the cooling medium is variable. The presence of a surface layer with zero latent heat is given a special consideration. Comparison of the proposed formula with the direct field measurements and the calculations carried out by others shows a satisfactory coincidence. For the simplified boundary conditions, the formular reduces to a known analytical solution.
Moments of the size distribution in radical polymerization
Authors: Katz Stanley , Saidel Gerald M. 
Published: June 2004

AbstractFor a number of polymerization models, we have developed equations that enable one to follow in time the moments of the polymer size distribution and the conversion. The exact and approximate solutions for the leading moments of the size distribution are presented for polymerization with initiation, propagation, and termination by combination. Approximate solutions for polymerizations with the additions of termination by disproportionation, chain transfer to monomer, and chain transfer to solvent show how these reactions decrease the average polymer size. From a simple model that exhibits autoacceleration a concomitant increase in the average polymer size also occurs.
Convective diffusion in a rectangular duct with one catalytic wall—laminar flow—arbitrary reaction order
Authors: Solbrig Charles W. , Gidaspow Dimitri 
Published: June 2004

AbstractIn a recent experimental study of reaction rates measured in a rectangular duct with a reaction of arbitrary order occurring on one wall, the results were analyzed in terms of an infinite parallel plate duct. The subject of this paper is the determination of the requirements necessary to treat a rectangular duct as a flat duct in the fully developed laminar flow regime. To this end, the rectangular duct problem is solved numerically. The results obtained show that mixing‐cup concentrations, average wall concentrations, and Nusselt numbers for any aspect ratio γ (between a square duct and parallel plates) may be estimated from the parallel plate results when a reduced distance is used. These parameters vary only slightly with aspect ratio. If the actual distance instead of this reduced coordinate is used, an aspect ratio of one to ten would be required to obtain results which are accurate to 6%. These conclusions are not valid for a catalytic reactor with four catalytic walls.
Heterogeneous and homogeneous reactions in a tubular reactor
Authors: Solomon R. L. , Hudson J. L. 
Published: June 2004

AbstractIrreversible, first‐order, simultaneous heterogeneous and homogeneous reactions in an isothermal tubular reactor under laminar flow conditions are studied. Accurate values of the eigenvalues, eigenfunctions, and radial concentration profiles are found for the dilute system. Criteria are given as to when the homogeneous reaction may be neglected with respect to the heterogeneous reaction and vice versa. It is found that for a certain range of the rate parameters well‐known limiting solutions apply. Outside this range, the new solutions must be used.