bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vaporization at the base of bubbles of different shape during nucleate boiling of water
Authors: Hospeti N. B. , Mesler R. B. 
Published: June 2004

AbstractDifferently shaped bubbles were observed growing during nucleate boiling of water at atomspheric pressure. The surface temperature beneath the bubbles was measured simultaneously with a fast response surface thermocouple. The evaporation from the base necessary to account for the observed cooling was calculated. A comparison of the ratio of vapor volume formed at the base to the total volume of the bubble shows a dependency on bubble shape. The ratio is smallest for spherical bubbles, largest for hemispherical and intermediate for oblate bubbles.
Internal flow mechanism in filter cakes
Authors: Shirato Mompei , Sambuichi Masao , Kato Hiroo , Aragaki Tsutomu 
Published: June 2004

AbstractThe definition of filtration resistance is modified by considering relative solid‐liquid velocity.The internal flow mechanism in a filter cake is reexamined in view of the movement of solids during compression. Under conditions of short filtrations involving highly concentrated slurries, the velocity of solids is shown to be comparable to the velocity of the liquid. A differential equation is proposed for the flow through compressible cakes in which the pressure gradient is assumed proportional to the difference in average velocities of the liquid and solid rather than to the average velocity of the liquid alone.An improved definition of the average filtration resistance is developed on the basis of the new flow equation.
Rotational stability in viscoelastic liquids: Theory
Authors: Ginn R. F. , Denn M. M. 
Published: June 2004

AbstractThe onset of secondary motions between rotating concentric cylinders is related to the viscometric normal stress functions for a class of viscoelastic liquids which includes dilute polymer solutions. Both increased and decreased stability relative to a corresponding Newtonian liquid are possible for a given material, depending upon the particular relation between the viscometric functions and the geometric constants of the equipment. This predicted behavior is in agreement with experimental observations.
Rotational stability and measurement of normal stress functions in dilute polymer solutions
Authors: Denn M. M. , Roisman J. J. 
Published: June 2004

AbstractThe onset of rotational flow instability was determined experimentally for dilute solutions of six polymers. In general, the onset of secondary motions occurred later than for a Newtonian liquid of equal apparent viscosity, although, depending upon geometric ratios, some instabilities occurred earlier than in the Newtonian liquid. The stability theory of Ginn and Denn was used to calculate viscometric normal stress functions for ten solutions, with excellent agreement obtained with rheogoniometric measurements of the primary normal stress measurements in all but three cases. Torque measurements of the laminar secondary motion following instability showed some frictional drags significantly less than those observed in Newtonian liquids, a phenomenon analogous to the turbulent drag reduction observed previously in dilute polymer solutions.
Cyclic steady state diffusion
Authors: Simmons P. J. , Spinner I. H. 
Published: June 2004

AbstractAnalytic equations describing cyclic steady state diffusion in which the diffusivity depends on the direction of transfer, as well as on the system, have been obtained.By imposing the cyclic steady state constraint, of periodically repetitive concentration profiles, simultaneous solution of separate Fick's diffusion equations for the on‐off segments of the cycle results in the desired equatins. The method of solution can be extended to more complex diffusion problems, such as coupled diffusion processes. Shallow bed experiments have been performed on particle‐diffusion controlled, cyclic steady state ion exchange. Agreement between the predicted and experimental transfer was obtained. Variables and parameters affecting cyclic steady state diffusion are discussed.
A drop dispersal model for rinsing
Authors: Tallmadge John A. , Li Sik U. 
Published: June 2004

AbstractA new theory for convection‐free rinsing of flat plates was developed to include the drop dispersal mechanism as well as the previously considered diffusion mechanism. Cases where carryover is unequal to dragout were also included in the model. Based on film distribution data, the model offers better agreement with rinse data. The effect of drain time on film distribution and bottom drop volume was also investigated.
Packed distillation columns and absorbers at steady state operation
Authors: Rubac R. E. , McDaniel Ronald , Holland C. D. 
Published: June 2004

AbstractIn this paper the concept of a mass transfer section is applied to problems involving packed distillation columns and packed absorbers. When this concept is employed, the resulting equations required to describe packed distillation columns and packed absorbers are identical in form to those required to describe distillation columns and absorbers with plates. Data from the results of two field tests are presented and analyzed.
Thermal and material transport in nonisothermal packed beds
Authors: Schertz William W. , Bischoff Kenneth B. 
Published: June 2004

AbstractThe turbulent transport of mass, energy, and momentum was studied in a 4 in. diameter cylindrical column packed with 0.3 in. diameter stoneware spheres. Helium was used as a tracer material, with air as the mainstream fluid. The concentration of tracer present, the temperature, and the velocity of the gas were measured at several axial and radial increments. These data were analyzed numerically to obtain the radial component of the effective thermal conductivity and the radial component of the mass‐dispersion coefficient as functions of radial position. Experimental conditions covered isothermal determinations at room temperature and nonisothermal determinations in which a temperature gradient was established in the radial direction. Significant differences were found between the isothermal and strongly nonisothermal results, primarily for the velocity profiles and thermal conductivities. Correlations were developed for the local values of the parameters.
Foaming and frothing related to system physical properties in a small perforated plate distillation column
Authors: Lowry R. P. , Van Winkle Matthew 
Published: June 2004

AbstractExperimental froth heights occurring on a perforated distillation tray were correlated with the determining system physical properties under distillation conditions. A photographic technique was used to measure accurately the foam and froth heights, produced in the 4 in. square test section of a laboratory distillation column, for several points in the composition range of five binary systems. Plate design parameters and operating vapor and liquid rates were held constant throughout the experimental study.The froth height results from this investigation (11), as well as those from studies (17) of a 6 in. distillation column, show a linear relation with the expression, UA2 ρv/(ρL — ρV), the frothing factor, for the ranges of the physical properties investigated.The foam height results of this study indicate that the mass transfer surface tension gradient, the heat transfer gradient, and the absolute value of surface tension all contribute to foam formation and stability. Because of the complex relation between the surface tension gradient and the frothing factor in relation to the degree of foaming, as well as the effects of other influencing variables, a unique correlation of the foam height data resulting from mass transture of the effect for several of the data points.This investigation was conducted to obtain experimental data which could provide a basis for correlation of the foam and froth heights occuring on an operating perforated distillation tray with system physical properties.
Transport of heat and mass between liquids and spherical particles in an agitated tank
Authors: Brian P. L. T. , Hales H. B. , Sherwood T. K. 
Published: June 2004

AbstractData are reported for heat transfer from water to melting ice spheres and for mass transfer in the case of dissolving spheres of pivalic acid suspended in water agitated in a stirred vessel. The transport coefficients are found to depend on agitator power input but not on agitator design, in agreement with the Kolmogoroff theory. These experimental results are used with others in the literature to develop a correlation involving Nusselt and Prandtl or Schmidt numbers together with a dimensionless group involving agitation power. The correlation is essentially independent of solid‐liquid density ratio in the range 0.8 to 1.25, and in this range the gravity group also appears to be unimportant.
Converging flows of viscoelastic materials
Authors: Metzner A. B. , Uebler E. A. , Fong C. F. Chan Man 
Published: June 2004

AbstractThe kinematics of converging velocity fields such as those found in flows from a large duct or reservoir into a small tube are especially simple in the case of viscoelastic materials as they may be approximated by means of a diagonal deformation rate tensor. This result is shown to be valid in the present study in which aqueous polymeric solutions were utilized and is inferred as having been valid under the experimental conditions employed by Bagley in studies of molten polymers. It is suggested that asymptotic approximations based upon the diagonality of the deformation rate tensor may be of general use in analysis of flows of viscoelastic materials, that is, they could represent, potentially, simplifying approximations comparable in utility to the boundary layer approximations employed commonly in the analysis of flows of Newtonian fluids.An interesting prediction of the present analysis is that for flows from a large duct into a small one a plot of isotropic pressure vs. axial position exhibits a minimum near the inlet to the smaller duct. Experimental results are presented in partial support of this unusual behavior. The analysis also suggests that an orfice jet thrust technique for measurement of normal stresses, closely related to recent independent studies by Middleman and by Fabula, may be an indirect but especially simple and sensitive tool for measurement of material properties.
Flow properties of suspensions with high solids concentration
Authors: Gay E. C. , Nelson P. A. , Armstrong W. P. 
Published: June 2004

AbstractEquations were developed for evaluating the laminar flow behavior of high‐solids suspensions from the physical properties of the liquid and solid components. A technique was developed for calculating suspension flow rates as a function of pressure drop. The technique is applicable to the design of pipe lines. Flow measurements were made in pipe‐line viscometers of a unique design that minimized entrance and exit effects. Experimental flow data were obtained for suspensions consisting of nickel, alumina, copper, or glass solids in sodium, xylene, or glycerine vehicles with solids concentrations of 28 to 55 vol. %. The basis for the correlation of the data was an analytical investigation of the flow behavior that considered the particle‐particle interaction that takes place in a settled suspension. The correlation equations fit all systems investigated. They take into account the effects of liquid viscosity, liquid and solid densities, particle size, size distribution, particle surface area, volume fraction of solids in the suspension, and volume fraction of solids at maximum settled conditions.
The kinetics of condensation polymerization
Authors: Secor R. M. 
Published: June 2004

AbstractThe final stages of condensation polymerization are characterized by a rapid rise in molecular weight, as the condensation product is formed and diffuses out of the polymer. The process occurring is one of desorption accompanied by a chemical reaction. The penetration theory equations for a generalized condensation polymerization reaction have been solved and some solutions are presented. The penetration theory solution, obtained by finite‐difference computations, is compared with an analytical solution for the special case of no diffusional resistance.
Single‐phase flow through porous media
Authors: Slattery John C. 
Published: June 2004

AbstractThe local volume average of the equation of motion is taken for an incompressible fluid flowing through a porous structure under conditions such that inertial effects may be neglected. The result has two terms beyond a pressure gradient: g, the force per unit volume which a flowing fluid exerts on a porous structure, and the divergence of the local volume‐averaged extra stress tensor (viscous portion of the stress tensor).Constitutive equations for g are examined with the aid of the principle of material indifference. When g is assumed to be a function of the velocity of the fluid relative to the solid as well as various scalars, the usual results for a nonoriented (isotropic) porous structure are obtained. When g is assumed to be a function of the local porosity gradient as well, we derive a new expression for g applicable to oriented (anisotropic) porous structures.For a Newtonian fluid with a constant viscosity, the divergence of the local volume‐averaged extra stress tensor is proportional to the Laplacian of the averaged velocity vector. Boundary conditions for the averaged velocity vector are discussed. Three problems are solved for the flow of an incompressible Newtonian fluid in a nonoriented permeable medium. These solutions, as well as an order‐of‐magnitude analysis, suggest that we may often neglect both the Laplacian of average velocity and the boundary conditions for the tangential components of averaged velocity at an impermeable wall.Two specific constitutive equations for g are proposed for the flow of incompressible Noll simple fluids in nonoriented porous structures. Flow through a porous medium bounded by an impermeable cylindrical surface is solved for these two constitutive equations, and the results are compared with previously available experimental data.
An equation of state for methane in the gas and liquid phases
Authors: Vennix A. J. , Kobayashi Riki 
Published: June 2004

AbstractAn equation of state was developed which represented experimental methane P‐V‐T data over the temperature range of 130 to 625° K. for pressures to 10,000 lb./sq. in. obs. with densities to 0.36 g./cc. For 598 experimental points the mean square percent deviation in the predicted pressures was 0.07% with only 10 points having deviations above 0.2%. The low density limit of the equation predicted second virial coefficients within 1 cc./mole of the accepted values for temperatures above 200° K.The equation was developed by first analyzing isochoric data from the saturation point to the high temperature or pressure limit. An expression was then obtained, reflecting qualitative behavior of the isochores, that reproduced experimental data along each isochore with an average pressure error of 0.02% and a maximum error of 0.08%. This expression had the form P = A + BT + C exp [E (T — T0)] + D exp (k—F/T) where k and T0 were normalizing constants and A through F were functions of density. From the density dependence of these parameters a single expression was obtained which fit the entire range of experimental data.
Free convection melting of ice spheres
Authors: Vanier C. R. , Tien Chi 
Published: June 2004

AbstractExperimental results have been obtained for heat transfer to melting ice spheres by measuring the rate of change of apparent weight. It is found that the traditional correlation format of Nusselt number against Rayleigh number is satisfactory only for bulk temperatures above 7°C. Average Nusselt numbers obtained from the sphere experiments are closely related to previous theoretical work with vertical flat plates.
The effect of surface active agents on interphase mass transfer
Authors: Burnett J. C. , Himmelblau D. M. 
Published: June 2004

AbstractThe effect of various soluble and insoluble surface active agents on the absorption of ammonia into a static aqueous system was studied. Saturated straight‐chain hydrocarbons with four to twenty‐two carbon atoms and polar end groups were selected as the surface active agents to be studied. Alcohol, amine, and amide end groups were investigated. Most of the insoluble surface active agents, which were studied as films, were found to decrease the ammonia absorption rate. There was a definite correlation between the amount of mass transfer reduction and the hydrocarbon chain length, while the effect of the various end groups appeared to depend on the chain length. Surface mass transfer coefficients were computed for each surface active agent that retarded mass transfer. Most of the soluble surface active agents were found to increase the ammonia absorption rates. For all cases of enhanced mass transfer, movements in the interface could be observed. It was concluded that the interfacial movements were caused by the Marangoni effect. In general, as the chain length of the surface active agent decreased, the mass transfer enhancement increased. A mathematical model based on a surface renewal theory was fitted to the experimental data.
Distillation decoupling
Authors: Luyben William L. 
Published: June 2004

AbstractThis paper presents a quantitative study of two types of decoupling elements to achieve non‐interacting feedback control of overhead and bottoms compositions in binary distillation. Ideal decoupling, where the closed loop response of each loop is the same as it would be if the other loop were on manual control, and simplified decoupling, where two interaction compensators are used to isolate each loop, are investigated.The decoupling elements themselves are physically realizable in both cases, but unstable loops develop with ideal decoupling in higher purity columns because of increased positive feedback. Simplified decoupling gave effective, stable, noninteracting loops for all the cases studied.The decoupling elements are designed in the frequency domain from a linear model of the column, and their effectiveness is tested by digital simulation of the nonlinear column model.
Effect of molecular weight distribution on the shear dependence of viscosity in polymer systems
Authors: Graessley William W. , Segal Leon 
Published: June 2004

AbstractThe viscosity of concentrated solutions of polystyrene were measured in steady shearing flow with a Weissenberg rheogoniometer. The polymers ranged in weight average molecular weight M̄w from 97,000 to 3,370,000 and in distribution breadth M̄w/M̄n from 1.05 to 3.1. The solvent was n‐butylbenzene, and the solutions ranged in concentration from 0.20 to 0.55 g./cc. These data were supplemented by measurements on bulk polystyrenes and polyethylenes with distribution breadths as high as M̄w/M̄n = 20. Master curves of reduced viscosity vs. reduced shear rate were calculated theoretically for each molecular weight distribution. The experimental viscosity data superimposed satisfactorily on these curves and furnished the viscosity at zero shear rate τ0 and an experimental time constant τ0 for each solution. The time constant paralleled closely the Rouse relaxation time τR in all systems. Residual variations in the ratio τ0/τR with molecular weight and concentration correlated uniquely with the product cM̄w. These results indicate that the viscosity behavior of a polymer can be predicted with reasonable accuracy from data on its molecular weight distribution.
Radial migration of spherical particles in couette systems
Authors: Halow J. S. , Wills G. B. 
Published: June 2004

AbstractSeveral studies have been made in Couette systems of the primary motion (angular translation and rotation) of spheres suspended in viscous liquids. Radial migration trajectories, however, have been unreported for single spheres.In this study, a prediction of radial migration is developed and compared with experimental measurements. The predicted trajectories were found to agree well with the measured ones.Ultimately, radially migrating spheres reached an equilibrium position located approximately midway between the cylinder walls. The model developed predicted an equilibrium position just slightly inside the midpoint, while measured equilibrium positions fell between the midpoint and 0.4, the annular thickness from the inner cylinder walls. The differences in equilibrium positions are attributed to the approximate nature of the model.
Temperature profiles for polymer melts in tube flow
Authors: Collins Edward A. , Filisko Frank E. 
Published: June 2004

AbstractThe present state of the theory of nonisothermal tube flow is inadequate to predict the behavior of polymer melts. In addition, relatively few experimental measurements on radial temperature profiles of polymer melts in the tube flow have been reported. For non‐Newtonian systems, the separation of viscous losses due to frictional heat generation and those due to the effect of shear rate is a formidable problem which has hampered progress. This paper will describe a method of measuring shear induced heating and present experimental data on radial temperature profiles in tube flow. A novel method of estimating the velocity profile is also described.
Light intensity profiles in a perfectly mixed photoreactor
Authors: Jacobm Solomon M. , Dranoff Joshua S. 
Published: June 2004

AbstractThe light intensity distribution in a perfectly mixed photoreactor has been studied experimentally and analytically. Experimental measurements of intensities within the reactor were made with a specially designed light probe. These data were then used to test the validity of a model which treats the ultraviolet lamp as a linear source radiating in all directions. It was found that this model, which seems appropriate and allows reasonable computations, is somewhat in error owing to the neglect of the finite size of the lamp and the existence of reflection and refraction effects within the reactor. An empirical correction function was determined for use with the model which then yields predictions in close agreement with experimental data when the reactor is filled with a light absorbing liquid.
Analytical and experimental studies of facilitated transport
Authors: Ward W. J. 
Published: June 2004

AbstractFacilitated transport is a process in which permeation through a liquid film is chemically augmented. Because of the scientific and engineering interest in this phenomenon, the purpose of this work was to carry out a detailed mathematical and experimental investigation of facilitated transport. The differential equations describing facilitated transport are presented, and a generally applicable numerical solution recently developed by G. M. Roe for this type of boundary value problem is summarized. The experimental investigation consisted of measuring the steady state rate of transport of nitric oxide through thin films of ferrous chloride solution and of determining independently the values of the system parameters of which the nitric oxide flux was a function. The experimental results were accurately predicted by using the model developed by Roe. This is the first demonstration of a general quantitative understanding of facilitated transport.
Thermodynamic properties of the system N2O4⇌2NO2⇌2NO + O2
Authors: Seshadri D. N. , Viswanath D. S. , Kuloor N. R. 
Published: June 2004

AbstractThermodynamic properties of the chemically reactive system N2O4⇌ 2NO2⇌ 2NO + O2have been evaluated over a pressure range of 0.005 to 200.0 atm. and a temperature range of 200° to 900°K. by making use of Lennard‐Jones potential. In these calculations, the dissociation of nitrogen tetroxide to nitrogen dioxide, nitric oxide and oxygen, and the effect of pressure on the equilibrium constants for the system of reactions N2O4⇌ 2NO2and 2NO2⇌ 2NO + O2have been taken into account.