bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical models for surface renewal in heat and mass transfer: Part I. Dependence of average transport coefficients on age distribution
Authors: Koppel L. B. , Patel R. D. , Holmes J. T. 
Published: June 2004

AbstractAverage transport coefficients for different transport models are computed by using widely varying distributions of residence times of elements at the transporting surface. It is shown that for typical transport models, the shapes of the residence time and age distributions have an insignificant effect on the average transport coefficient. Operational techniques for calculating average coefficients and for constructing delayed versions of age distributions are presented.
A simplified method for the prediction of multicomponent adsorption equilibria from single gas isotherms
Authors: Kidnay A. J. , Myers A. L. 
Published: June 2004

AbstractThe ideal adsorbed solution theory of Myers and Prausnitz (7) provides an accurate and thermodynamically consistent method for predicting multicomponent adsorption equilibria. The major difficulty in the application of this theory lies in the calculation of the spreading pressure curves for the pure adsorbates. The purpose of this article is to show that in many cases of practical interest, the spreading pressure calculations may be greatly simplified or altogether eliminated with little or no loss in the accuracy of the calculations. The problem of adsorption azeotropy is also briefly discussed.
Model calculations for capillary condensation
Authors: Melrose James C. 
Published: June 2004

AbstractCapillary phenomena arising from vapor phase condensation in porous media are discussed in the light of an exact interface curvature theory and a self‐consistent thermodynamic theory. The system studied consists of liquid condensed in the form of pendular rings at the contact points between identical spherical particles. The geometrical parameters—the curvature, the confined volume, and the surface area of the liquid‐vapor interface—must be expressed in terms of incomplete elliptic integrals. In addition several corrections are introduced for the classical Kelvin relation for lowering of vapor pressure. One of these is based on the density dependence of the isothermal thermodynamic susceptibility. Since the susceptibility vanishes at large negative pressures, an upper limit to the curvature is established. The balance equation for the extensive free energy is considered from the point of view of hydrostatic principles.
Cocurrent stratified flow of immiscible liquids
Authors: Darby Ron , Akers W. W. 
Published: June 2004

AbstractVelocity profile data were taken in both phases of a cocurrent stratified flow system of two immiscible liquids in the turbulent regime. The data were correlated by a method which combined Pai's results for Poiseuille and Couette flows between parallel plates, resulting in values of the drag coefficients for the wall and interface for both phases. These and other dependent parameters were correlated with flow conditions over a range of flow rates for both phases. Correlations of all parameters except the interfacial drag coefficient were found to be symmetrical; that is, a given correlation applied equally well to data from either phase. The interfacial drag coefficient, on the other hand, depended primarily upon the flow intensity of the upper phase, in a manner which was further dependent upon which phase was the faster.
The absorption of carbon dioxide in aqueous monoethanolamine in a laminar jet
Authors: Thomas W. J. 
Published: June 2004

AbstractThe mechanism of the absorption of carbon dioxide by an aqueous solution of monethanol‐amine has been studied. Experimental results for the absorption of carbon dioxide into a laminar jet of amine solution have been used to examine the transfer process. Previously this process has been considered as pseudo unimolecular, but this has been disproved. When considered as a second‐order, fast, irreversible reaction by the film, penetration, and corrected penetration theories, the results are most satisfactory. It is possible by the corrected penetration theory to correlate the results such as to predict kL/kLo to within 3% of the experimentally determined value.
The dynamic behavior of a fixed‐bed catalytic reactor
Authors: Leder Frederic , Butt John B. 
Published: June 2004

AbstractThe dynamic behavior of a fixed‐bed catalytic reactor was studied under isothermal conditions by means of frequency response analysis. The investigation was conducted over a range of nonreacting and reacting conditions by using the hydrogen‐oxygen combination over supported platinum as the reaction system. The kinetics of the surface catalysis of this reaction were investigated separately and then were incorporated into the analysis of frequency response data under reaction conditions.A method was developed whereby nonlinear chemical reaction effects appearing in the frequency response measurements could be separated from hydrodynamic factors for a plug flow reactor. Use is made of the describing function technique, often used to approximate nonlinear servomechanism response, to accomplish this. It is shown by this method that Peclet numbers measured for the reacting system agree with those measured in the absence of reaction.Based on the semitheoretical value of 2 for the Peclet group at high Reynolds numbers, a value of 0.73 sq. cm./min. was determined for the effective diffusion coefficient of hydrogen at 100°C. within the porous catalyst particles. Analysis of frequency response data in which this diffusion is not accounted for leads to Peclet numbers which are unreasonable in view of previously reported results.
Entrained particle collection in packed beds
Authors: Jackson Stephen , Calvert Seymour 
Published: June 2004

AbstractSmall particle collection in packed beds is described by an inertial impaction theory which fits experimental observations. Rings, saddles, spheres, and spherical packing of 1/2‐, 1‐, and 1 1/2‐in. size were used at air velocities up to 30 ft./sec. for the collection of an oil mist of known size. Particle collection efficiencies up to 50% for 1.0‐micron particles were obtained.
Design variable selection to simplify process calculations
Authors: Lee Wooyoung , Christensen James H. , Rudd Dale F. 
Published: June 2004

AbstractDuring the analysis of a large process system, the values of certain design variables must be preassigned to allow the solution of the design equations. A careless selection of these distinguished variables can lead to trouble, magnifying computational problems above what need be. A method is proposed for determining a set of design variables which could minimize the computational labor associated with process analysis. This work is part of a larger project on the computer aided design of process systems.
Upper and lower bounds for solutions to the transport equation
Authors: Finlayson Bruce A. , Scriven L. E. 
Published: June 2004

AbstractThe collocation method and a maximum principle are used to generate pointwise, improvable upper and lower bounds for solutions of the transport equation. This new method of analysis is applicable to the unsteady state transport equation with a specified velocity field as well as to other problems which have a maximum principle. An application to unsteady state transfer to a fluid in ideal stagnation flow illustrates the method.
Physical and chemical absorption in two‐phase annular and dispersed horizontal flow
Authors: Wales Charles E. 
Published: June 2004

AbstractOverall mass transfer coefficients for physical desorption and chemical absorption of carbon dioxide in annular and dispersed two‐phase flow in a 1‐in. horizontal pipe have been measured. These coefficients have been correlated with gas and liquid flow rates and with the normality of the sodium hydroxide solutions used.A new method of analysis was used to separate overall coefficients into individual gas and liquid film coefficients. Penetration theory equations were used to calculate the effective inter‐facial surface area and the penetrotion contact time. Changes in these variables have been explained in terms of the changes in flow pattern.
Heat transfer and frost formation inside a liquid nitrogen‐cooled tube
Authors: Reid R. C. , Brian P. L. T. , Weber M. E. 
Published: June 2004

AbstractAn experimental study was undertaken of simultaneous heat transfer and frost deposition inside a liquid nitrogen‐cooled tube for a range of humidities and Reynolds numbers. The data indicate that diffusion of water vapor within the frost layer caused the frost density and thermal conductivity to increase with time. The increase was so great that the heat transfer rate became constant even while frost continued to accumulate. In a separate study the thermal conductivities of frosts formed on a cryogenic surface were measured and found to be lower than values near the freezing point of water.
Laminar flow heat transfer
Authors: Christiansen E. B. , Jensen Gordon E. , Tao Fan‐Sheng 
Published: June 2004

AbstractNumerical solutions of the equations of motion and energy for the heating of non‐Newtonian fluids in rectilinear, axisymmetric laminar flow in tubes of circular cross section are extended to the case of cooling at constant tube‐wall temperature. The fluid density, heat capacity, and thermal conductivity are assumed constant, but the flow properties are represented by the temperature‐dependent equation τ =m(Ṡ exp ΔH‡/RT)n. The results are presented as plots of averageNNuvs.NGz, with flow and temperature‐effect indices as parameters. The mean deviation of experimental data for the cooling of aqueous CMC and carbopol dispersions from the numerical solutions is ±8%.
Vapor‐liquid equilibria of light hydrocarbons at low temperatures and high pressures: The methane‐n‐heptane system
Authors: Chang Harry L. , Hurt Lewis J. , Kobayashi Riki 
Published: June 2004

AbstractRecent experimental observations of the phase behavior of methane–n‐paraffin hydrocarbon binary systems are used to make a phase rule analysis of such systems. The vapor‐liquid equilibria of light hydrocarbon systems are complicated by liquid‐liquid immiscibility and solids formation at low temperatures.The system studied here has limited liquid phase miscibility with a quadruple point involving a gas phase, two liquid phases, and a solid phase.Experimental techniques were developed to sample and analyze gas phases containing concentrations of n‐heptane in the range of 0.00001 mole fraction with good precision. Binary K values for methane and n‐heptane are reported at intervals of 20°F. from 0° to −100°F. for pressures up to the criticals for the mixtures. The results are reported numerically and illustrated graphically. Additional phase observations were made below the critical temperature of methane to confirm and extend the phase behavior of the methane–n‐heptane system as reported by Kohn.
Freezing process based on the inversion of melting points due to applied pressure
Authors: Cheng Chen‐Yen , Cheng Sing‐Wang 
Published: June 2004

AbstractA new freezing process for the desalination of seawater is being developed which utilizes a unique way of upgrading heat energy where there is no gas phase involved. This method takes advantage of the abnormal melting point curve of water. Water melts at a lower temperature under a higher applied pressure (that is, (dp/dT) melting < 0), while an ordinary substance melts at a higher temperature under a higher applied pressure (that is, (dP/dT) melting > 0). Due to this differnce a substance which melts at a temperature lower than the freezing point of an aqueous solution may melt at a temperature higher than the melting point of water at a sufficiently high pressure.Thus, a suitably selected working medium can be used to form a cyclic auxiliary system which can be incorporated with the main system to: remove the heat of crystallization of water in the partial freezing of an aqueous solution by melting the working medium at a low pressure, and to supply the heat for melting the ice by solidifying the working medium at a sufficiently high pressure.
Vapor‐liquid equilibrium for the system hydrogen—benzene—cyclohexane—n‐hexane
Authors: Brainard Alan J. , Williams Brymer 
Published: June 2004

AbstractThis paper presents vapor‐liquid equilibrium data for the system hydrogen—benzene—cyclohexane—n‐hexane over the pressure range of 500 to 2,000 lb./sq.in.abs. and the temperature range of 200° to 300°F. Experimental equipment was constructed that was capable of operating at pressures of 3,000 lb./sq.in.abs. and at temperatures of 400°F. A static equilibrium cell, which had a sample port for both the liquid and vapor phases, was employed. Separation of the hydrogen from the hydrocarbons by means of a liquid nitrogen cold trap was utilized before performing the hydrocarbon analyses on a mass spectrometer. Three hydrocarbon mixtures were charged to the equilibrium cell, and for each charge, isotherms of 200°, 250°, and 300°F. were run for equilibrium pressures of 500, 1,000, 1,500 and 2,000 lb./sq.in.abs. These thirty‐six quaternary equilibrium runs resulted in a total of one hundred and forty‐four equilibrium data points. In addition, four binary equilibrium runs were determined both for the hydrogen‐benzene and hydrogen‐cyclohexane systems. A modified version of the Chao‐Seader correlation was used to predict the data. This correlation was able to predict all the quaternary equilibrium ratios with an average deviation of 4.86%.
The gas and liquid solubility relations in hydrocarbon‐water systems
Authors: Rebert Charles J. , Hayworth Kenneth E. 
Published: June 2004

AbstractThe typical solubility boundaries of binary simple hydrocarbon‐water systems are outlined for temperatures and pressures ranging into the neighborhood of the critical point for pure water. These systems are characterized by two unique states, a critical vaporization end point and a critical solution end point. The former defines the limit of mutual solubility of two liquid phases, and the latter defines a point of complete solubility at a minimum pressure. Experimental P‐T‐x data for cyclohexane‐water and n‐hexane–water mixtures are presented.
Transient response and feed‐forward control of a distillation tower subject to a sequence of upsets
Authors: Distefano G. P. , May F. P. , Huckaba C. E. 
Published: June 2004

AbstractA mathematical model of dynamic distillation was verified experimentally for transients resulting from a sequence of upsets in operating conditions, that is, for upsets occurring in the unsteady state before the effects of previous upsets died out.The equations for feed‐forward control of the top product composition by reflux ratio control action were derived and a computer program was written in FORTRAN for solution on a digital computer. This control model was employed in the feed‐forward control of an experimental distillation column when subjected to an upset in feed composition.Experimental data were obtained from a twelve‐plate, 10‐in. diameter distillation column with a methanol‐tertiary butyl alcohol system. The numerical technique employed is a completely general divided difference method which can be utilized in the solution of any system of first‐order differential equations.
Heat and mass transfer between an evaporative interface in a porous medium and an external gas stream
Authors: Morgan Robert P. , Yerazunis Stephen 
Published: June 2004

AbstractSteady state heat and mass transfer between a submerged evaporative interface in a porous medium and an external gas stream were analyzed theoretically. Local and average evaporation rates for laminar and turbulent flow over a flat plate as well as for fully developed laminar or turbulent flow near the thermal entry region of a duct were obtained as a function of the position of the evaporative interface. Calculated local evaporation rates are significantly lower than values computed by Luikov, who did not take into account the variation of evaporative surface temperature with recession, indicated both by the present analysis and by observations related to the drying of thick porous materials. Application to the analysis of the drying process is discussed.
Kinetics of the nonisothermal pyrolysis of propane
Authors: Kershenbaum Lester S. , Martin Joseph J. 
Published: June 2004

AbstractA method was devised to yield chemical reaction kinetic parameters from nonisothermal, nonisobaric flow experiments. The system studied was the pyrolysis of propane at high temperatures (800° to 1,000°C.). At these temperatures the rates of the various reactions are so high that a batch or even an isothermal flow experiment is impossible. To keep the conversions low so that the initial stages of decomposition could be studied, the feed gas was diluted with varying amounts of nitrogen. Residence times in the reactor were in the millisecond range. The reactor exit gas was analyzed by mass spectrometry. The method developed in this work is not limited to simple kinetic studies, but can be useful in complicated series and parallel reactions which often require nonisothermal conditions.
A generalized differentiation method for interpreting rheological data of time‐independent fluids
Authors: Lescarboura J. A. , Eichstadt F. J. , Swift G. W. 
Published: June 2004

AbstractA generalized differentiation method for analyzing rheological data of time‐independent fluids is presented. The method is demonstrated to be valid and useful in analyzing rheological data and comparing such data obtained on the same time‐independent fluid in rheometers of the capillary, annular, coaxial cylinder rotational, and falling cylinder types.
Gas absorption in packed columns: Liquid phase resistance in the loading region
Authors: Vivian J. E. , Brian P. L. T. , Krukonis V. J. 
Published: June 2004

AbstractData on liquid phase‐controlled gas absorption in the loading regime are presented. Carbon dioxide was desorbed from water by using a 6‐in. Diameter tower and 1/2‐ and 3/4‐in. Ceramic rings. Below the loading point, HL increases approximately as the 0.25 power of the liquid rate and is independent of gas rate. In the loading regime, however, it was found that at high gas rates HL increases less rapidly and may even decrease with increase in liquid rate. At intermediate gas rates, the effect of liquid rate on HL is intermediate. These effects are explained on the basis of the interaction of the gas and liquid flow rates and the effect of this interaction on KL and a. The results suggest that in some cases tower capacity may be increased without increasing HL.
Gas compressibility factors at high temperature and high pressure by the Burnett method: Methyl chloride
Authors: Suh K. W. , Storvick T. S. 
Published: June 2004

AbstractAn instrument based on the Burnett method for determining gas compressibility at high temperature and high pressure was constructed. An estimate of the accumulated measurement errors indicate the data should be accurate to eight parts in 10,000. The instrument was calibrated up to 1,000 lb./sq.in. with helium at 200° and 300°C. The average absolute difference between the experimental and the smoothed helium compressibility factor data was 4 and 6 parts/100,000 for the 200° and 300°C. isotherms, respectively. Compressibility factor data for methyl chloride from 200° to 350°C. at 25°C. intervals and at pressures to 5,000 lb./sq.in. are reported. Second virial coefficients for helium and methyl chloride were also obtained.
Kinetics of xylene isomerization over silica‐alumina catalyst
Authors: Hanson K. L. , Engel A. J. 
Published: June 2004

AbstractEleven mixtures of the three isomers of xylene and ethylbenzene were isomerized over a silica‐alumina catalyst in a differential tubular reactor at temperatures from 700° to 900°F. and pressures from 0 to 100 lb./sq. in. gauge. Analysis showed that meta‐xylene isomerizes reversibly to ortho‐ and para‐xylene, but the direct interconversion of ortho‐xylene to meta‐xylene does not occur. Further, it appears that the isomerization reactions are first order and, by the Hougen‐Watson technique, follow a single‐site reaction model.
Behavior of suspended matter in rapidly accelerating viscoelastic fluids: The Uebler effect
Authors: Metzner A. B. 
Published: June 2004

AbstractThe observation that large bubbles entrained in accelerating viscoelastic fluids may suddenly stop and remain stationary for long periods of time, although imbedded in a region of high fluid velocities, is noted and described. An analysis of this phenomenon, termed the Uebler effect, shows that it may be expected to occur with all particulate matter provided that the continuum field fluid is accelerating sufficiently rapidly to generate high stresses as a result of fluid stretching, and provided these stresses change sufficiently rapidly in the direction of the velocity vector in the flow field.
A method for the noninteracting control of a class of linear multivariable systems
Authors: Foster Robert D. , Stevens William F. 
Published: June 2004

AbstractA method is presented by which a particular class of interacting linear multivariable systems may be decoupled into independent, first‐order subsystems containing a single output as a function of a single manipulatable input and a single measurable input. This is accomplished by application of compensators in the form of feedforward amplifiers and proportional plus derivative feedback controllers. Simultaneous application of a stabilizing feedback controller and a feedforward amplifier to each decoupled subsystem results in perfect control of system outputs yi (t), that is, yi (t) = 0 for all t ≧ 0. In addition, the compensating device contains degrees of freedom that make it possible to set output forms within any limits desired in the case that subsystem feedforward controllers operate imperfectly, and obtain better fit between the linear system model, which forms the basis for controller design, and the corresponding nonlinear system model.
A fourth parameter for the vapor pressure and entropy of vaporization of polar fluids
Authors: Halm Roland L. , Stiel Leonard I. 
Published: June 2004

AbstractPitzer's acentric factor approach has been extended to the vapor pressure and entropy of vaporization of polar fluids. Normal fluid vapor pressure functions have been determined for 0.44 ≤TR< 0.56. A polarity factor has been defined and polar correction terms established for the vapor pressure for 0.44 ≤TR< 0.70 and for the entropy of vaporization for 0.56 <TR< 0.72. The polar correction terms enable the accurate calculation of the vapor pressure and entropy of vaporization of a polar fluid from its normal boiling point and normal latent heat of vaporization. The results of this study also form the basis for the extension of this approach to other thermodynamic properties of polar fluids.
Frequency response of gas mixing in a fluidized‐bed reactor
Authors: Barnstone Leonard A. , Harriott Peter 
Published: June 2004

AbstractFrequency response methods were used to compare dynamic models for gas mixing and first‐order reaction in a fluidized‐bed reactor and for the experimental determination of interphase transfer characteristics. Theoretical predictions of frequency response characteristics were derived for two models based on the two‐phase theory of fluidization. Experimental frequency response for a 1‐ft. high bed were correlated better by a model based on perfect mixing in the dense phase than by a model based on plug flow in the dense phase. Excellent correlation was also obtained by a simple empirical model.