bluuebunny/crossref_metadata_2025 huggingface dataset:
Ignition limits for pilot‐stabilized high‐velocity, turbulent, butane‐air mixtures at low pressure
Authors: Griskey Richard G. , Archer David H.
Published: June 2004

Limiting velocities were determined by finding the composition at which the flame first spread into the unburned gases for a given velocity and turbulent intensity. These composition were represented by intersections of curves of flame widths at certain combustion chamber positions plotted vs. composition.
The critical temperatures of multicomponent hydrocarbon systems
Authors: Grieves Robert B. , Thodos George
Published: June 2004

The critical temperature of any multicomponent hydrocarbon system may be established solely from the normal boiling points of the pure constituents. Such mixtures may include normal paraffins, isoparaffins, olefins, acetylenes, naphthenes, and aromatics and may contain an unlimited number of components.

An expression has been developed for the prediction of the critical temperatures of mixtures and has been tested on fifty‐five hydrocarbon systems containing from two to five components. For 208 binary mixtures the deviations from reported values were calculated, and the maximum deviations resulting from each system were averaged for the forty‐one binary systems to produce an average maximum deviation of 0.91% based on degrees absolute. For twenty‐eight multicomponent mixtures reported for nine ternary, two quaternary, and three quinary systems the average deviation was 1.03%.

This method presents a simple and accurate means of establishing the critical temperature of any multicomponent hydrocarbon mixture as long as the ratio of the normal boiling points of the heaviest and lightest components present in the mixture does not exceed the prescribed limits.
Concentration fluctuations in a stirred baffled vessel
Authors: Manning F. S. , Wilhelm R. H.
Published: June 2004

A stirred vessel is maintained in a quasisteady state by continuously introducing water and a conductive tracer solution and continuously removing the resulting mixture by overflow. Detailed properties of the system are elucidated by measuring tracer concentration changes with a conductivity probe in a volume element of the order of 0.3 cu. mm. By the use of suitable electronic equipment the following statistical concentration parameters are measured in experiments with three diameters of flat‐bladed turbines and with a tenfold range of rotational speed: temporal mean, total root‐mean‐square fluctuation, spectral distribution of fluctuations, and Eulerian micro time scale. Results are interpreted in terms of behavior of time‐average and fluctuation measures in three regions, the generation region within the impeller volume, the decay region which starts in the horizontal fluid sheet issuing from the impeller, and the recirculation flow region in the vessel.

Generation of concentration fluctuations within the confines of the impeller is described in terms of a model involving gross mixing, without significant decay, in the wake of each flat blade. Distributions of mean and fluctuating concentrations are suggested to provide a measure of uniformity in the vessel as a whole. The former, in particular, was remarkably constant throughout the vessel.
The viscosity of ammonia: Experimental measurements for the dense gaseous phase and a reduced state correlation for the gaseous and liquid regions
Authors: Shimotake Hiroshi , Thodos George
Published: June 2004

The unsteady state flow of ammonia gas has been investigated to determine its viscosity at elevated pressures and moderate temperatures. This was accomplished in an experimental unit of the transpiration type which was calibrated with nitrogen, for which viscosity data at high pressures were available in the literature. To obtain the viscosity at the operating conditions the basic differential equation for the unsteady state flow caused by the experimental procedure was developed and solved with an IBM‐650 digital computer.

Experimental runs were conducted for pressures ranging from 250 to 5,000 lb./sq. in. and temperatures from 100° to 200°C. This information has been used to establish the viscosity of ammonia at these dense phase conditions for which no viscosities had been previously reported. These values were used to develop a unique correlation between the residual viscosity and the density. This correlation then enabled the determination of ammonia's viscosity at the critical point μc = 2,395×10−5 centipoises.

The Enskog viscosity equation has been used with the values resulting from this study and PVT data for ammonia to develop a relationship for the probability of nearness. This relationship enables viscosities to be calculated for densities up to 0.450 g./cc. which are in close agreement with the experimental values.
Deviation from the inverse‐thickness relation in gas‐metal permeation
Authors: Phillips J. R. , Dodge B. F.
Published: June 2004

The permeation rate of hydrogen through cylindrical membranes of type 321 stainless steel was determined under a wide range of conditions. The pressure was varied from 0.1 to 30.0 atm. and the temperature from 300° to 800°C. Four permeation membranes were used with wall thicknesses of 0.0252, 0.1003, 0.1011, and 0.2475 cm.

The permeation rate was found to deviate from the square‐root‐of‐pressure and inverse‐thickness relations predicted by the Richardson equation. Slow surface reactions are considered to be the cause of the observed deviations. The permeation data were correlated by a semiempirical interfacial resistance model.

Permeation rates were observed to increase with time of membrane exposure to hydrogen. It is believed this resulted from changing surface activity.
Perturbation velocities in gas‐liquid partition chromatographic columns
Authors: Stalkup Fred I. , Deans H. A.
Published: June 2004

The characteristic velocities in binary and particular ternary cases allow straightforward calculation of equilibrium partition coefficients for components present in both flowing and fixed phases. It is shown in the case of a general N‐component flowing phase that N‐1 characteristic velocities arise. In theory N‐1 equilibrium partition coefficients can be obtained from measurements of these velocities. It is also shown that radioactive tagging of one component provides a distinct characteristic velocity, which can be used either to obtain the Nth equilibrium coefficient or to eliminate a parameter which is especially subject to experimental error.

The analytically determined characteristic velocities are compared with pulse velocities obtained from numerical solution of the original balance equations. The agreement over a range of solute concentrations is excellent.
General mathematical model for mass transfer accompanied by chemical reaction
Authors: Huang Chen‐Jung , Kuo Chiang‐Hai
Published: June 2004

The present paper concerns the mechanism of mass transfer accompanied by a first‐order irreversible chemical reaction between two phases. Based on the film‐penetration concept a general mathematical model to describe the physico‐chemical behavior at the interface has been formulated. Mass transfer mechanism may be analyzed and evaluated in terms of the dimensionless groups appearing in the derived equations.

For limiting conditions the derived general equations can be reduced to those based on the simple postulations such as the film theory, the penetration theory, and the surface renewal theory. For nonlimiting cases the film‐penetration concept provides information which cannot be obtained by either the film theory or the surface renewal theory alone.

Experimental results appearing in literature show that the physical mass transfer coefficient is proportional to the molecular diffusivity to the v‐th power and that v varies widely between 0.15 and 1.0. The film‐penetration concept theoretically predicts this v‐variation, whereas, in accordance with the film theory or the surface renewal theory, v has to be a certain fixed value.

It is shown that if an accurate physical mass transfer coefficient is available, the film‐penetration concept, the film theory, and the surface renewal theory all predict practically the same effect of chemical reaction on the mass transfer rate. However if the chemical mass transfer coefficient is to be predicted without an accurate physical transfer coefficient, the choice of the theory or the mechanism may become important.
Diffusivity of hydrogen in pure iron
Authors: Bryan W. L. , Dodge B. F.
Published: June 2004

The rate of permeation of hydrogen through a highly purified iron (Ferrovac E) was measured over a pressure range of 1/30 to 300 atm. and a temperature range of 126° to 693°C. The effect of cold working of the annealed metal and of hydrogen purity were also studied. Permeability, diffusivity, and solubility were obtained from the data. Permeation rate was linear with square root of fugacity rather than pressure. No difference in ϕ or D between the annealed and cold worked tube was observed. LogDvs. 1/Twas linear over the whole range of temperature, in disagreement with recent work showing a break in the plot at about 400°C. The calculated activation energy was lower than values reported in the literature. Solubility agreed well with most previous work and did not show the break in the solubility vs. temperature curve found by some recent investigators. No ageing effect was observed nor any difference between the two grades of hydrogen. All the evidence shows that diffusion through the metal is the controlling rate process in this case.
Effect of carbon monoxide in causing nonuniform gasification of graphite by carbon dioxide
Authors: Austin L. G. , Walker P. L.
Published: June 2004

Existing theories on the effect of mass transport on the rate (uniformity) of chemical reaction within a porous solid assume that the reaction is of integer order. However the carbon‐carbon‐dioxide reaction has the kinetic rate form, rate = k1p/(1 + k2pCO + k3p). For conditions where the retarding effect of carbon monoxide is very pronounced, the buildup of small concentrations of carbon monoxide within the porous graphite can lead to appreciable nonuniformity of gasification. Thus the criteria normally used to predict uniformity of gasification break down. A numerical integration of the combined differential equation of mass transport and chemical reaction has been performed, with rate constants for the carbon‐carbon dioxide reaction taken from the literature. The results indicate that extreme nonuniformity of reaction can exist even when the change in carbon dioxide concentration from the exterior of the sample to the interior is small. The results are similar to experimental determinations of non‐uniformity of gasification, obtained by determining the porosity of reacted graphite samples as a function of depth from the reacting face. Experimentally nonuniformity of reaction was observed for gasification rates a hundredfold lower than the usual Thiele criteria would predict, probably because of carbon monoxide inhibition.
Limitations on a generalized velocity distribution
Authors: Brodkey Robert S.
Published: June 2004

The usefulness of the Pai power series representation for the velocity distribution has been limited because of the lack of knowledge about the functional dependence of the empirical integer constant on the Reynolds number. Correlations are given for this constant for both Newtonian and non‐Newtonian materials; however, certain limitations are found as a result of actual velocity distribution calculations.

The equation represents the distribution over most of the turbulent core at all Reynolds numbers, but deviates widely at about a y+ of 75 for Reynolds numbers greater than 100,000. Below this, the equation provides a satisfactory representation over the entire flow field.
Continuous propagation of microorganisms
Authors: Fredrickson A. G. , Tsuchiya H. M.
Published: June 2004

Microorganisms undergo a cycle of maturation during their life‐span in a proliferating culture. This gives rise to a distribution of degrees of cellular maturation in the culture. The gross rate of any metabolic process carried on by the culture is therefore an average over all degrees of maturation present.

Equations embodying the life‐cycle concept are developed for cultures of organisms which proliferate by binary fission and do not form spores. The equations are solved for the age distribution in the special case of a continuous, steady state fermentation. Expressions for calculating gross metabolic rates and cell size distributions are derived. Finally, the stability of the steady state fermentor is discussed.
An analysis of slug flow heat transfer in an eccentric annulus
Authors: Snyder William T.
Published: June 2004

A solution is presented for the temperature distribution in a fluid flowing in an eccentric annulus formed with circular cyclinders under the assumption of slug flow. The flow is assumed to be fully developed thermally with constant thermophysical properties. The outer surface is assumed to be adiabatic and the inner surface temperature is assumed to be independent of circumferential position. General expressions and numerical results for a typical set of conditions are presented for the quantities, local heat flux, local heat transfer coefficient, adiabatic surface temperature distribution, and average Nusselt number. The application of the present results to the prediction of turbulent heat transfer to liquid metals is indicated, and a comparison with other liquid metal heat transfer analyses is presented.
Prediction of vapor‐liquid equilibria with the Benedict‐Webb‐Rubin equation of state
Authors: Lin Min‐Shuey , Naphtali Leonard M.
Published: June 2004

The prediction of vapor‐liquid equilibria with the Benedict‐Webb‐Rubin (BWR) equation of state has been restudied. It was found that the suitability of the equation of state to represent fully the behavior of the constituents is the main factor which affects the accuracy of the prediction. To improve the representation of the pure component data by means of equation of state it is necessary to modify the present form of the BWR equation of state. A tentative form of modification of the BWR equation of state has been chosen. Although the modified equation is still subject to further evaluation and refinement, satisfactory results have been obtained for the prediction of four binary systems containing nitrogen and carbon dioxide (nitrogen‐methane. methane‐carbon dioxide, propane‐carbon dioxide, and n‐butane‐carbon dioxide).

The method of nonlinear estimation has been used to fit the coefficients in the equation of state to either vapor‐pressure data or P‐V‐T data.
Formation of moderate‐size bubbles
Authors: Mahoney John F. , Wenzel Leonard A.
Published: June 2004

Bubbles were formed in water when air was passed through a single square‐edged orifice which had been drilled in a glass plate. The glass plate was 0.05 in. thick, and the orifice diameter was 1/8 in. The air chambers above the liquid surface and below the orifice plate were varied. The extreme values of these volumes were 0.00975 and 0.195 cu. ft. The air rate through the orifice, Q was as great as 200 × 10−5 cu. ft./sec. Bubble frequencies, f, were as great as 16 sec.−1

Both the upper and lower chamber volume influenced markedly the relationship between f and Q. A relationship that predicts sets of upper and lower chamber volumes that result in the same f vs. Q relation is given. A two‐parameter equation that gives f as a function of Q is presented.

Wettability of the orifice plate and the liquid depth over the orifice plate were also considered as independent variables.
Analytical solution of equilibrium‐stage operations—application to rectification with varying saturated enthalpies and to liquid‐liquid extraction
Authors: Martin Joseph J.
Published: June 2004

A complete analytical solution is developed for the number of equilibrium stages in separations processes for which operating and equilibrium lines are not necessarily straight. The resulting equations are solutions of a Riccati difference equation and are applied to liquid‐liquid extraction and the distillation of a binary mixture where the liquid and vapor flows are not constant because of the variation of the saturated liquid and vapor enthalpies with concentration. A specific example is given for the separation of ethyl alcohol and water in which the equilibrium curve is highly nonlinear and where a large number of plates are required in a pinch region. Another example is given for the extraction of methylcyclopentane from its solution in n‐hexane using aniline as a selective solvent.
Nuclear radiation‐induced cracking of n‐hexadecane
Authors: Guernsey Edwin O. , Shaw Henry , Smith William E.
Published: June 2004

A representative paraffin hydrocarbon in the gas oil range, n‐hexadecane, has been irradiated in the Industrial Reactor Laboratories' 5 mw. nuclear research reactor. In the vapor phase radiation‐induced cracking proceeded efficiently, and G values for radiation conversion of n‐hexadecane were 200 to 1,200 at temperatures near 750°F. Total conversions of n‐hexadecane were less than 3 wt. % and were due only in part to the radiation effect. The distributions of products which were obtained were similar to those which result from thermal cracking of n‐hexadecane. There were however significant increases in the yields of hydroger., reductions in the yields of very light hydrocarbons and small yields of high molecular weight products. At temperatures above 850°F. extensive thermal cracking obscured the effects of radiation.

In liquid phase radiation‐induced cracking at 750°F. conversions of n‐hexadecane up to 15 wt. % have been obtained at liquid spaces velocities near 4 v./hr./v. In many exposures nearly one‐half of this conversion was attributed to the direct utilization of radiation. The corresponding G values were 30 to 60. The products obtained have been accounted for by adding together the products which would be expected from a radiation‐induced reaction producing primarily dimer, from radiation‐initiated chain propagated cracking, and thermally initiated chain cracking. The product distribution from these reactions can be changed by variation of the cracking temperature and/or radiation dose.
Characterization of multiple variable linear systems from random inputs
Authors: Angus R. M. , Lapidus Leon
Published: June 2004

The time constant of a continuous stirred‐tank reactor and the transfer function of a simulated second‐order system with two random inputs were determined. In the first case the experimental result agreed within 11% of the known value; in the second case the results agreed with those predicted from a theoretical analysis. To determine the transfer matrix of a fifth‐order system an impractical amount of medium speed computer time was required; the results were not considered satisfactory. However the length of calculation compares favorably with other methods of total identification for processes which have extraneous noise associated with them. Because of this the application of the present technique in adaptive control systems appears to be favorable.
The role of porosity in filtration: VI. New definition of filtration resistance
Authors: Tiller F. M. , Shirato Mompei
Published: June 2004

The definition of filtration resistance is re‐examined in view of the new theory (12) of the variation of flow rate with respect to distance through a filter cake. In the new definition it is shown that the filtration resistance depends upon slurry concentration as well as applied pressure. A correction factor modifying the specific filtration resistance previously defined by Ruth (5, 6) is developed.

Where the hydraulic pressure variation within a cake is known, methods are presented for calculating the variation of flow rate with respect to distance and the change of filtration resistance in relation to slurry concentration.
The mechanism of liquid‐phase resistance to gas absorption in a packed column
Authors: Vivian J. Edward , King C. Judson
Published: June 2004

The desorption of five sparingly soluble gases from water into air in a packed tower was studied at five different flow conditions. At 25°C. these systems represent a range of liquid‐phase diffusivity from 1.4 × 10−5 to 6.3 × 10−5 sq. cm./sec. The mass transfer coefficient was found to vary as the 0.5 power of liquid‐phase diffusivity in all cases. This result, obtained through the variation of diffusivity alone, is in agreement with the predictions of penetration theory and strongly suggests a penetration mechanism based on molecular processes and independent of eddy processes during a surface lifetime. A discussion of the nature of the diffusion and surface renewal process in flow over packing is included.
Transport characteristics of suspensions: Part IX. Representation of periodic phenomena on a flow regime diagram for dilute suspension transport
Authors: Thomas David G.
Published: June 2004

Four different flow regimes may be identified during transport of dilute suspensions of solid particles through horizontal pipes by liquids in turbulent flow as the velocity is varied. The regimes may be characterized by the distribution of solids in the channel. In two of the regimes the bulk of the material is immediately adjacent to the bottom of the channel and is clumped up either into transverse waves (dunes or islands) with a reproducible periodicity or into longitudinal waves (long stria). The definition of the other two regimes is somewhat more arbitrary but may qualitatively be described as heterogeneous or homogeneous flow. Extensive studies of the conditions under which transverse and longitudinal waves occurred, when combined with results of previous studies, showed that all four of these flow regimes may be conveniently represented on a single diagram in which the terminal‐settling velocity divided by the friction velocity and the Reynolds number on particle diameter and friction velocity are the coordinates. Because the particle Reynolds number based on the terminal‐settling velocity can be uniquely defined as an additional parametre on such a diagram the particular flow behavior for any given combination of system and particle characteristics can be readily determined.
Optimization by Pontryagin's maximum principle on the analog computer
Authors: Lee E. Stanley
Published: June 2004

A computational method has been developed for obtaining the solution to a class of optimization problems by the combined use of the maximum principle and a maximum (or minimum) seeking technique on the analogue computer. Various maximum seeking techniques can be used for this method. However if the random search technique is used, this computational method has the advantage of being able to investigate a large number of operating (or controlling) variables.

The calculation procedure is essentially a trial‐and‐error procedure which is alternately integration and maximum seeking operations. The variables over which the system is to be optimized are approximated by a finite number of straight line segments n. Thus the maximum (or minimum) of the Hamiltonian function which is obtained by the maximum principle need only be obtained at n + 1 points along the optimization path (or trajectory).

To illustrate the use of the method the optimum operating variable profiles (or gradients) in a tubular chemical reactor were computed.

The present method, in addition to making it easier to investigate systems with a moderate number of state variables, can be used to solve problems with almost any kind of constraints and performance index encountered in ordinary optimum design problems. It offers some possibilities for on‐line optimizing control of a process. A special purpose analogue computer could be built for this use.
Laminar flow in the inlet section of parallel plates
Authors: Wang Y. L. , Longwell P. A.
Published: June 2004

Velocity distributions, pressure gradients, and overall pressure drops are presented. A definite concavity was found in the velocity profile near the entrance for case I. In case II, which is more realistic physically, very definite effects are transmitted upstream, and the velocity distributions downstream show little concavity.
Lateral solids mixing in fludized‐packed beds
Authors: Gabor John D.
Published: June 2004

A study was made of the mixing of particulate solids fluidized in the voids of a packed bed of larger nonfluidized bodies. In such a system heat transfer rates are dependent on the movement of fluidized particles. Recently application has been made of inert fluidized particles in chemical reactor systems to improve the removal of the heat generated by the exothermic reaction of the larger particles. A measure of the particle movement was achieved in this study by the determination of diffusion coefficients for the rates of solids mixing in the lateral direction when metal shot is fluidized in the voids of spherical and cylindrical packing. Experimental data showed that the particle mixing was related to the void structure of the packed bed by a random walk model. A general correlation was made for fluidized‐solids diffusivity in spherically packed beds.
Correlation of thermodynamic properties of amine‐water solution with molecular structure
Authors: Davison R. R. , Hood D. W. , Harris W. D.
Published: June 2004

The solutions of amines and water are in several respects among the most interesting that have been studied. They give some of the most perfect examples of lower consolute temperatures with fast breaking, almost flat solubility curves near the critical solution point. Their heat and entropy of solution are very high, and with few other solutions do the thermodynamic properties show greater sensitivity to molecular structure.

The activity coefficients for these solutions are inordinately difficult to fit with equations such as the Margules, Redlich‐Kister, etc., requiring as many as six constants. It has been found however that some of the properties can be correlated in terms of structural parameters which are measures of the steric and inductive contribution of the substituent groups. A very good correlation of the heat of solution at infinite dilution of amines in water is given. An equation of the Margules type employing orthogonal polynomials is given for which the constants are similarly correlated. Five six‐carbon atom amines at 10°C. are included in the latter correlations, and the activity coefficients of all of these are represented in terms of two structural parameters.
An experimental investigation of the inherent uncertainty in pool boiling critical heat fluxes to saturated water
Authors: Gambill Wallace
Published: June 2004

The inherent uncertainty of the critical heat flux in saturated pool boiling has been inconclusively debated for some time. In an effort to ascertain this uncertainty a series of 234 tests was conducted at atmospheric pressure with saturated water outside horizontal, a.c. heated, 0.234‐in. O.D., A‐nickel tubes in an open 6 × 6 × 9‐in. deep pool. Approximately fifty tests were conducted with each of four test sections which were protected from physical burnout by a detector circuit which terminated the applied current before the wall temperature exceeded approximately 450°F. The maximum relative uncertainty in the derived values of critical heat flux was ±3%.

For all the tests the minimum, average, and maximum critical fluxes were 0.201 × 106, 0.436 × 106, and 0.596 × 106 B.t.u./hr. sq. ft., respectively, and the average critical wall superheat was 41°F. The surface roughness of the test sections remained essentially unchanged during the program. The data show that there is an inherent uncertainty or scatter band in the critical heat flux under conditions of minimum surface variability, and that solely hydrodynamic theories of burnout do not fully represent the phenomenon, since surface condition can constitute a significant influence.
A kinetic study of sulfur dioxide in aqueous solution with radioactive tracers
Authors: Wang J. C. , Himmelblau D. M.
Published: June 2004

A kinetic study was made of the homogeneous reactions in the sulfur dioxide‐sodium bisulfite‐water system, with a radioactive tracer technique. By operating this system at chemical equilibrium but at isotopic disequilibrium the influence of the diffusion of sulfur dioxide into and out of the aqueous solution could be divorced from the kinetic effects of the chemical reaction. It was then possible to follow the rate of reaction of this system by analyzing the radioactive sulfur‐35 in the form of gaseous sulfur dioxide, with the Bernstein‐Ballentine technique.

Data were collected at temperatures of 0° to 20°C. and at pH ranges from 1.25 to 4.3. Analysis and correlation of the experimental data by different kinetic models demonstrated that the classical reaction SO2 + H2O ⇌ H+ + HSO3− represented the experimental data best from a macroscopic viewpoint. Because of the low pH conditions employed it was not possible to obtain rate data for the reaction SO2 + OH− ⇌ HSO3.

Forward and reverse rate constants are reported for the first time for this system.
Virial coefficients for argon, methane, nitrogen, and xenon
Authors: Gyorog Donald A. , Obert Edward F.
Published: June 2004

The second, third, and fourth virial coefficients for argon, methane, nitrogen, and xenon have been established by various methods to satisfy experimental compressibility data and also to satisfy graphical computations of the property deviation relationships of Δuoand Δho.
Tube flow of non‐Newtonian polymer solutions: Part II. Turbulent flow
Authors: Meter Donald M.
Published: June 2004

A correlation of turbulent tube‐flow friction factors for non‐Newtonian polymer solutions, based upon the fluid property τ1/2 defined in Part I, has been found to represent data taken on seven solutions of Natrosol hydroxyethylcellulose in ½‐ and 1‐in, I.D. smooth tubes, with an average accuracy of 10.8%. Also, for these seven solutions, this correlation gives somewhat more accurate predictions of the point of transition into turbulent flow than are made by the Ryan‐Johnson stability theory.

The correlation must be considered only provisional, however, because it does not simplify to the limiting case of extremely dilute solutions. Plausible extensions based on models of steady‐flow non‐Newtonian viscosity behavior, and other possible correlation schemes utilizing viscoelastic fluid properties, are briefly discussed.
A study of interstitial liquid flow in foam. Part II. Experimental verification and observations
Authors: Leonard Ralph A. , Lemlich Robert
Published: June 2004

Experimental results obtained over a wide range of variables from three different foam fractionation columns support the theory developed in Part I.
Analysis of phase boundary motion in diffusion‐controlled processes: Part II. Application to evaporation from a flat surface
Authors: Griffin J. R. , Coughanowr D. R.
Published: June 2004

In an earlier paper (1), three general methods of approaching the moving‐boundary problems were developed. In the present work, these three methods are applied in detail to the solution of the problem of evaporation from a flat surface into a vapor phase of infinite depth. While this particular problem has been solved before (2,3), it has been chosen as an example here because all three methods apply directly.
Thermal pressure applied to the prediction of viscosity of simple substances in the dense gaseous and liquid regions
Authors: Lennert David A. , Thodos George
Published: June 2004

The reduced thermal pressure‐temperature ratio has been used to relate residual viscosity modulus for argon, krypton, and xenon into a unique relationship applicable for the dense gaseous and liquid regions. For these monatomic substances the critical compressibility factor is zc= 0.291. Values of (∂PR/∂TR)pRvs. (μ —μ*)ζ on log‐log coordinates produced a linear relationship. For these simple substances, this relationship was used to predict viscosities with an average deviation of 3.0% for fifty eight experimental values. This relationship was also applied for the prediction of viscosities for nitrogen, oxygen and carbon dioxide.

The approach developed in this study merits further examination with several additional substances. The lack of adequate thermal pressures in the dense gaseous and liquid regions of substances other than argon limits the use of this study to substances having critical compressibility factors zc= 0.291.
The influence of mass transfer on a countercurrent liquid‐liquid fluidized system
Authors: Dunn I. , Lapidus Leon , Elgin J. C.
Published: June 2004

The present work is concerned with an experimental study of the influence of mass transfer on the holdup of countercurrent liquid‐liquid fluidized systems and the effect of solute on droplet coalescence. Of particular importance in the results obtained is the dramatic demonstration that mass transfer greatly influences the holdup when solute is being extracted from the discontinuous phase loading to strong coalescence.
Generalized thermodynamic properties of real gases: Part II. Generalized Benedict‐Webb‐Rubin equation of state for real gases
Authors: Su Gouq‐Jen , Viswanath D. S.
Published: June 2004

By use of a least‐squares technique, a set of parameters for the generalized Benedict‐Webb‐Rubin equation is determined. The generalization of the equation is based on the modified theorem of corresponding states. The generalized equation shows a grand average absolute deviation of 1.6% in predicting the observed values of reduced pressure. The set of constants has been determined for densities up to twice the critical density in the reduced pressure range of 0 to 40.0 and a reduced temperature range of 1.0 to 15.0. The recommended generalized constants are Ao′ = 0.24180980, ao′ = 0.04407059 a′ α′ = 0.11369478 × 10−3, Bo′ = 0.07643101, b′ = 0.03715171, Co′ = 0.21217005, c′ = 0.06448001 and γ′ = 0.06.
Feedback control of an overdetermined storage system
Authors: Wilde Douglass J.
Published: June 2004

Although it is already known how to apply feedforward control to an overdetermined system (2), feedback control is more difficult because overdeterminancy involves more measured variables than controllers. Feedback control is possible for a system of production units separated by storage tanks holding intermediate products and perturbed by random external upsets (1). Two types of feedback control are studied: local control in which each manipulated variable is controlled by the levels in the two tanks immediately adjacent, and central control in which all the levels simultaneously affect each manipulated variable. The behavior of these systems for three‐action linear controllers is described. Proportional local control is shown to have a structure similar to those of the unrefluxed countercurrent separation processes of the chemical industry. Such systems are therefore inherently stable. Central control, although requiring a more complicated equipment arrangement, actually has a simpler dynamic behavior because it cancels out interactions between controllers.
An experimental investigation of air bubble motion in a turbulent water stream
Authors: Baker James L. L. , Chao Bei T.
Published: June 2004

The motion of individual air bubbles in a water stream flowing turbulently in a 4 in. × 4 in. vertical conduit is investigated by photographic means. The bulk water velocity ranges from 40.8 to 267 cm./sec., corresponding to a system Reynolds number range of 48,600 to 386,000. Both tap and demineralized water were used at or near room temperatures. Air bubbles range from 0.038 to 0.70 cm. in equivalent radius and the corresponding bubble Reynolds number based on relative velocity ranges from 58 to 4,500.

The results indicated that the bubble relative velocity in a turbulent water stream is similar to the rise velocity of single bubbles through a quiescent liquid. It was found to be practically independent of the system Reynolds number for bubbles having an equivalent radius above 0.3 cm. Large fluctuations in the bubble velocities were noted in all cases. The drag coefficient is, in general, lower for the demineralized water tests than for tap water when the bubble Reynolds number is below 2,000. Above this value, a mergence of the drag coefficients for all tests occur with a peak of approximately 2.0 at a bubble Reynolds number of 3,000, which is lower than the nonflow value of 2.6.
Excess transport properties of light molecules
Authors: Rogers John D. , Brickwedde F. G.
Published: June 2004

A detailed study has been made of the excess viscosity of dense‐phase aragon, deuterium, helium‐3, helium‐4, para and normal hydrogen, neon, and nitrogen and of the excess thermal conductivity of normal hydrogen. A definite temperature dependence for the excess viscosity vs. density has been shown to exist for argon, helium‐4, hydrogen, and nitrogen and to be indicated for deuterium. The existing thermal conductivity data for hydrogen have been examined. A theoretical analysis for the qualitative behavior of excess thermal conductivity is given. The critical point viscosity values for all the species are given. Graphs, together with references to 1‐atm. data, are presented for computation of the transport properties.
Stability in distributed parameter systems
Authors: Amundson Neal R. , Raymond Lee R.
Published: June 2004

Three models of a catalyst particle are examined for existence of multiple steady states depending upon whether intraparticle heat conduction or diffusion is important. The particle with constant temperature but with intraparticle diffusion is examined in detail and a necessary and sufficient condition for the stability of the steady state is obtained. Calculations are made for a particle with both intraparticle diffusion and conduction and it is shown that there may be multiple steady states some of which are unstable to small perturbations.
The mixed suspension, mixed product removal crystallizer as a concept in crystallizer design
Authors: Randolph Alan D.
Published: June 2004

Simultaneous population and mass balances have been solved together with a generalized form of nucleation‐growth rate kinetics to obtain the form of crystal size distribution (CSD) for several idealized modes of crystallizer operation, including seed crystal removal, product classification, arbitrary solids concentration, and staged vessels. The effect of holding time and feed supersaturation on crystal size in a mixed suspension, mixed product removal (MSMPR) crystallizer was also studied. A representative CSD from an MSMPR crystallizer plus the relative kinetic order of nucleation to growth rate can be used to predict CSD from any of the above modes of operation.
The effect of concentration on diffusion coefficient in polymer solutions
Authors: Secor Robert M.
Published: June 2004

A microinterferometric method was used to measure the diffusion coefficient as a function of concentration in the system dimethylformamide‐polyacrylonitrile at 25°C. The diffusion coefficient increases with increasing polymer concentration up to the maximum employed, 17.72% by weight. The theoretical basis for this type of behavior is explained. The diffusion coefficient in the limit as the polymer concentration approaches zero was calculated from theory to be 0.30 × 10−6 sq.cm./sec. This value is consistent with the diffusion coefficients obtained experimentally.
Calorimetric determination of the isothermal pressure effect on the enthalpy of the propane‐benzene system
Authors: Yarborough Lyman , Edmister Wayne C.
Published: June 2004

An isothermal throttling calorimeter system has been built for obtaining the effects of pressure on the enthalpy of liquids and vapors. The propane‐benzene system has been studied at 200°0, 300°, and 400°F. for pressures from 200 to 1,000 Ib./sq.in.abs.

The experimental results are evaluated with respect to errors, and the data on the pure components are compared with values from the literature. Calculation methods are employed, and the calculated results are compared with the experimental data in an effort to evaluate the calculation methods.
Influence of catalyst particle size on reaction kinetics: Hydrogenation of ethylene on nickel
Authors: Fulton J. W. , Crosser O. K.
Published: June 2004

The influence of catalyst particle size upon the reaction rate was studied for the hydrogenation of ethylene with nickel‐on‐alumina in a packed‐bed flow reactor. A threefold increase in particle diameter through a critical size range (0.03‐ to 0.09‐cm. diameter, corresponding to a Reynolds number of around 1) produced a thirtyfold increase in reaction rate per unit external surface area. The behavior of the system indicates that this increase was due to the influence of external gas‐solid transport phenomena on the reaction kinetics. j‐Factor correlations were used to calculate the catalyst surface temperatures and concentrations, which were used to calculate Arrhenius activation energies and reaction rates from available rate expressions.
The viscosity of nonpolar gas mixtures at moderate and high pressures
Authors: Dean David E. , Stiel Leonard I.
Published: June 2004

A method has been developed for the calculation of the viscosity of nonpolar gas mixtures at moderate and elevated pressures from the molecular weights and critical constants of the components. By the use of available experimental data and appropriate pseudocritical constant rules, results obtained previously for the viscosity of pure gases have been extended to mixtures. Viscosity values calculated by the method developed in this study for a number of nonpolar gas mixtures were found to reproduce reported values with a high degree of accuracy.
Unsteady state mass transfer from gas bubbles—liquid phase resistance
Authors: Li Pang‐Sheng , West Frank B. , Vance William H. , Moulton Ralph W.
Published: June 2004

Liquid phase mass transfer coefficients were determined for streams of bubbles of pure oxygen, 10% carbon dioxide in air, and 10% chlorine in air all rising in water. The results were compared with coefficients predicted by Higbie's equation for unsteady state diffusion into transient films. The observed coefficients for oxygen and carbon dioxide were slightly higher than predicted. The experimental absorption coefficients based on the free chlorine concentrations were in good agreement with the predictions assuming simultaneous irreversible reaction with the transient water film and a pseudo first‐order reaction rate constant of 13.7 sec.−1.
Interstage mixing in an Oldshue‐Rushton liquid‐liquid extraction column
Authors: Gutoff Edger B.
Published: June 2004

Interstage mixing was measured in a 4‐in. Oldshue‐Rushton column fed with a salt solution at the top and distilled water at the diluted salt solution leaving at the top.

Mixing between stages is relatively slight at low agitator speeds, but increases very rapidly with speed once the turbulent region is reached. Interstage mixing is reported in terms of bulk backflows and also in terms of eddy diffusivities. The amount of interstage mixing is similar to that reported in the literature for rotating disc contactors.

Variations in the horizontal baffle plate design were also studied.
Studies of boiling heat transfer with electrical fields: Part I. Effect of applied A. C. voltage on boiling heat transfer to water in forced circulation
Authors: Markels Michael , Durfee Robert L.
Published: June 2004

Alternating current voltage (60 cycles/sec.) was found to increase boiling heat transfer rates and prevent film boiling for deionized water under forced convection at essentially ambient pressure. Steam was used to supply heat to the interior wall of a 0.292‐in. thick annulus, and voltages up to 5,000 v. were impressed across the region of vapor formation. The highest heat transfer rates reached were approximately twice the normal nucleate boiling peak. The application of voltage increased the boiling heat transfer over the entire range tested—mass flow rates up to 5.2 × 105 lb./hr.‐sq.ft. and exit qualities up to 4% by weight vapor. Data obtained from tests in which the external wall of the flow annulus was heated indicated an increase in heat flux up to 2,000 v., followed by a decrease in heat flux at voltages above 2,000 v.
Model simulation of stirred tank reactors
Authors: Manning F. S. , Wolf David , Keairns D. L.
Published: June 2004

Stirred tank reactor yields are successfully described by the following model. The impeller is considered to act as a local micro‐mixer that perfectly mixes the recirculating stream down to the molecular level. All other portions of the vessel act as a large volume macro‐mixer, throughout which the impeller discharge stream remains completely segregated. Changes in overall conversion due to variations in mean residence time, impeller size, and rev./min. as predicted by this micro‐ and macro‐mixer model agree with Worrell's data for a relatively slow, second‐order, irreversible reaction.
Gas absorption in a fin‐wall conduit
Authors: Sweeney Thomas L. , Calvert Seymour
Published: June 2004

Gas absorption and pressure drop were studied in a fin‐wall conduit; a fin‐wall conduit is a rectangular duct with fins placed on two internal walls perpendicular to the axis of flow. Pressure drop data were obtained with the air‐water system. Gas absorption data were obtained with the air‐ammonia‐water system, and were corrected for the expected liquid‐phase resistance by the use of oxygen desorption data. The pressure drop per transfer unit is on the order of 0.05 in. of water per transfer unit.
The condensation of mixed vapors
Authors: Estrin Joseph , Hayes T. W. , Drew T. B.
Published: June 2004

Although condensation from saturated mixed vapors upon a cold surface has been frequently explored experimentally, current theories describing this phenomenon have not been adequately tested. This work describes the condensation process in which two condensable components are involved and how, consequently, the mass transfer process is involved in their partial fractionation.

A discussion of the Bedingfield correction (3) for the effect of molecular weight difference of the diffusing components upon the mass transfer coefficient leads to its necessary association with the Ackermann factor (4, 5) for the general mass transfer effect. Data from two sets of experiments using different apparatuses demonstrate the use of this net corrective factor and also demonstrate the general applicability of the Drew‐Colburn mass transfer coefficient, for transfer processes in which more than one component transfers from one phase to another.
Heat transfer in a fuel cell battery
Authors: Gidaspow Dimitri , Baker Bernard S.
Published: June 2004

Analytical solutions were obtained for temperature distributions in a single adiabatic fuel cell with heat generation by TΔS, I2R, and polarization. With these results it is possible to characterize heat transfer in a battery with convection in the fuel and air streams, and with conduction of heat in three directions, by means of an average temperature for which an analytical solution was also obtained. Although the temperature can be kept within safe limits in low‐power density batteries, the results show that critical dimensions exist beyond which failure by thermal buckling will occur.
Scale‐Up for viscoelastic fluids
Authors: Slattery John C.
Published: June 2004

A suggestion is made as to how one might proceed to scale up a process involving an arbitrary viscoelastic fluid. The discussion is based upon Noll's theory of simple fluids. Turbulent flow in an infinitely long pipe is used as an illustration.
Performance of a packed distillation column with electrically heated packing
Authors: Somer Tarik G.
Published: June 2004

Electric current was applied across the coke packing of a glass column, distilling carbon tetrachloride‐benzene at total reflux. Heat generated by electricity boiled the liquid on the packing surface. Bubbles rising across the liquid film reduced its resistance to mass transfer, improving the column efficiency

Theoretical analysis and experimental results are presented.