bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow work exchanger
Authors: Cheng Chen‐Yen , Cheng Sing‐Wang , Fan Liang‐Tseng
Published: June 2004

In a high‐pressure process, feed streams are continually pressurized and product streams are continually depressurized. A flow work exchanger offers an efficient and economical scheme for simultaneously pressurizing a fluid stream and depressurizing a substantially equivalent volume of another fluid stream. Its applicability is however limited to fluids under condensed state. A flow work exchanger uses a displacement vessel to form a closed loop with a processing system. The displacement vessel is alternately filled by a low‐pressure feed and a high‐pressure product, both pressurized and depressurized, respectively, by substantially nonflow processes. The pressurized feed is pushed into the processing system by the high‐pressure product stream and the depressurized product stream is pushed out of the displacement vessel by the low‐pressure feed stream. The application of a flow work exchanger is illustrated by means of several high‐pressure processes and the direct and indirect advantages obtainable are described.
Analysis of data in reverse osmosis with porous cellulose acetate membranes used
Authors: Kimura Shoji , Sourirajan S.
Published: June 2004

Reverse osmosis experimental data for some inorganic salts with the porous cellulose acetate membrane used were analyzed to obtain their diffusivity in the membrane. A parameter including the diffusivity was found constant for each film in the concentration range investigated for a particular solute at a particular pressure. This parameter was also independent of feed flow rate. The effect of operating pressure on the parameter was found to depend on the film shrinkage. Mass transfer coefficient between the membrane and the feed solution was also obtained by the analysis, and this value was independently checked by the diffusion current method. Coincidence of these coefficients shows that the ordinary mass transfer coefficient can be used in reverse osmosis with the appropriate driving force. These facts facilitate the prediction of solute separation and membrane throughput rate in reverse osmosis.
Forced and natural convective mass transfer in multicomponent gaseous mixtures
Authors: Carlton Herbert E. , Oxley Joseph H.
Published: June 2004

The use of the Chilton‐Colburn analogy to obtain an effective film thickness over which the Stefan‐Maxwell equations can be integrated was confirmed for binary mixtures and found applicable for ternary, quaternary, and presumably higher order mixtures under conditions of nonequimolal counterdiffusion in a differential convective flow system. A method of averaging binary diffusivities was developed for use in computing the Schmidt number in these multicomponent systems. It was also found necessary to modify the usual Sherwood number, if there was a large molecular weight change across the diffusion barrier when the Chilton‐Colburn analogy was employed.
An experimental study of nonequimolal diffusion in ternary gas mixtures
Authors: Getzinger R. W. , Wilke C. R.
Published: June 2004

This work is an experimental test of the Stefan‐Maxwell equations as applied to cocurrent, steady state gaseous diffusion of two species through a stagnant third component. The Stefan capillary tube method was used to measure the diffusion rates. The use of constant evaporating binary liquid mixtures made possible boundary conditions that were invariant with time. Total molar losses were compared with the predictions of the theory to demonstrate the validity of the equations under conditions of a significant convective flux.
Gas‐liquid mass transfer with a tangentially moving interface: Part I. Theory
Authors: Byers Charles H. , King C. Judson
Published: June 2004

A theoretical investigation has been made of the effect of a moving interface upon gas‐liquid mass transfer, where the control of the mass transfer is entirely within the gas phase and where the control is distributed between the two phases. An analytical model is proposed for laminar interphase mass transfer in infinite media. Computer solutions have been obtained for gas‐liquid mass transfer in confined phases. A cocurrent moving interface increases mass transfer confficients over what they would be for the same flow rate without interfacial motion.
A correlation for pressure drop in two‐phase cocurrent flow in packed beds
Authors: Sweeney D. E.
Published: June 2004

A correlations has been developed from considerations of single‐phase flow behavior to predict pressure drop across packed beds for two‐phase cocurrent flow. The correlation does no require one of the assumptions made in previous correlations, and thus it was not necessary to relate empirically any dimensionless groups through the use of experimental two‐phase flow data. The only empiricism involved in the use of this correlation is that required in correlating single‐phase pressure drops through packed beds, an art well developed in the literature. The correlation as developed here is at least as accurate as previous correlations in this area and may be more reliable when used for two‐phase systems not previously studied experimentally.
The phase and volumetric relations in the helium—n‐butane system: Part II. Second virial coefficients for helium—n‐butane mixtures
Authors: Jones Allan E. , Kay Webster B.
Published: June 2004

The second virial coefficients of pure n‐butane and of two mixtures of helium and n‐butane were determined in the range 100° to 225°C. from isothermal compressibility measurements. Values of B11 (pure n‐butane) agree closely with those of McGlashan and Potter (11) at low temperatures and of Hirschfelder et al. (7) at higher temperatures. Values of the mixed second virial coefficient B12 were computed from the mixture data. B12 shows little variation with temperature over this interval. The interpretation of the data as the behavior of a mixture composed of hard sphere (helium) in a real gas (n‐butane) is discussed.
Sorption and diffusion of gaseous hydrocarbons in synthetic mordenite
Authors: Satterfield Charles N. , Frabetti Alton J.
Published: June 2004

Diffusion coefficients for the C1 to C4 paraffin hydrocarbon gases in single crystals of the synthetic zeolite (molecular sieve) sodium mordenite were determined from transient sorption rate and desorption rate measurements over the temperature range 25° to 140°C. and pressure range 0 to 20 cm. Hg, and found to be of the order of 10−9 to 10−10 sq. cm./sec. Diffusion coefficients for desorption were from three to sixty times smaller than those for sorption. Activation energies for methane and ethane were 1.7 and 1.9 kcal./mole, respectively.

Equilibrium sorption capacity and diffusion coefficients are markedly affected by the conditions of synthesis and by mechanical treatments such as grinding. For propane at 29°C. and at 2.0 cm. Hg pressure, the sorption capacity in 2.5 μ crystals was only 50% of that in 21 by 21 by 33 μ crystals and the diffusion coefficient was only 1/50 of that in the larger crystals. Light mechanical grinding of the larger crystals lowered the sorption capacity 30% and the diffusion coefficient by a factor of 35.
The growth of ice crystals in a stirred tank
Authors: Harriott Peter
Published: June 2004

Ice crystals were grown in water or sodium chloride solutions by direct contact with evaporating butane. In water subcooled 0.01° to 0.05°C., the particles grew about one‐quarter to one‐half as fast as fast as predicted from heat transfer correlations. The growth rates in 2% salt solution were about sevenfold lower than those obtained in water at the same subcooling, because the concentration difference for salt diffusion lowered the interface temperature. Calculations indicate the diffusion effect to be much greater for disk‐shaped particles than for spheres.
Bubble frequencies and departure volumes at subatmospheric pressures
Authors: Cole Robert
Published: June 2004

Bubble frequencies and departure volumes in nucleate pool boiling have been obtained for a variety of liquids at pressures ranging from 50 to 760 mm. Hg. The bubble dynamic data conclusively show the volumetric vapor flow rate to be a strong function of the Jakob number in qualitative agreement with the heat transfer measurements of Nickelson and Preckshot. The data also indicate the volumetric vapor flow rate per cross section to be independent of the Jakob number, in agreement with existing equations.
On thermal conductivity of liquids
Authors: Viswanath D. S.
Published: June 2004

The Bridgman equation for thermal conductivity of liquids is examined and a relation between sonic velocity and latent heat of vaporization is given. A correlation based on the hole theory of liquids is presented. This correlation predicts thermal conductivity in the temperature range of −20° to +80°C. for sixteen liquids, and at 20°C. for fifty liquids with an average absolute deviation of 9.5 and 5%, respectively. The correlation is also applied to liquid metals.
Experimental study of the viscous sublayer in turbulent pipe flow
Authors: Popovich A. T. , Hummel R. L.
Published: June 2004

A flash photolysis method for nondisturbing turbulent flow measurements has been applied to study conditions in the viscous sublayer in a square smooth pipe. Experimental results are obtained that are extremely difficult to obtain by any other known technique.

The results show that, adjacent to the wall, there is a layer of very small thickness y+ = 1.6 ± 0.4 in which a linear velocity gradient occurs virtually at all times, but the slope of the gradient changes with time. Beyond y+ = 34.6 essentially turbulent flow exists. In the transition region in between, very disturbed flow conditions prevail. However, the technique used clearly indicates the instantaneous velocity distribution in the flow field bewteen the wall and the fully turbulent region.

Statistical distributions of the instantaneous wall shear stress (evaluated from the slope of the velocity gradient), the laminar sublayer thickness, and the velocity at the edge of the laminar sublayer are obtained. It follows that the partial turbulence mechanism whereby the flow at a point is turbulent only a fraction of the time is, at least to an extent, responsible for the reduction of eddy diffusivity by kinematic viscosity close to the wall.

Experimental velocity profile obtained in the present investigation is compared with the proposed and experimental velocity profiles of other authors.
Analysis of liquid phase adsorption fractionation in fixed beds
Authors: Morton E. L. , Murrill P. W.
Published: June 2004

Liquid phase adsorption has been one of the latest unit operations to receive theoretical treatment because of the relative complexity of the mechanisms involved. The purpose of this investigation is to present an improved method for solving problems, especially where intraparticle diffusion is a rate controlling mechanism. Appropriate boundary conditions for liquid phase adsorption and a general nonlinear equilibrium relation are included in deriving a system of partial differential equations describing the process.

The mathematical model consists of a bulk phase material balance, an intraparticle diffusion equation, and a rate for interphase transfer; these equations must be solved simultaneously with the boundary conditions and equilibrium function. A numerical procedure is developed and discussed for use on a high‐speed computer.

The results are sets of computed curves for four liquid systems, each requiring a separate computer solution because of changes in feed concentration or equilibrium relationship. It is shown that for three of the four systems tested in this research, experimental data correlate with computed results better than in earlier work. Although the solution of this model has been carried out for particular examples, it should be applicable in the case of other liquid phase systems following the assumed mechanisms.
Vapor‐liquid equilibria at high pressures: Calculation of critical temperatures, volumes, and pressures of nonpolar mixtures
Authors: Chueh P. L. , Prausnitz J. M.
Published: June 2004

An analysis of critical data for a larger number of binary mixtures of normal fluids shows that the critical temperature and the critical volume can each be expressed as quadratic functions of the surface fraction. Each of these functions requires one adjustable parameter characteristic of the binary pair; for any family of chemical components, these parameters, upon suitable reduction, follow definite trends. It was shown that the surface fraction gives much better correlation than any other size‐weighted variable. For the critical pressure, however, no quadratic function was adequate. To calculate critical pressures, the correlations for critical temperature and critical volume were used in conjunction with a slightly altered version of the Redlich‐Kwong equation.

Generalizations to systems containing more than two components follow without additional assumptions. The methods presented in this paper provide good estimates for critical constants of multicomponent mixtures. These are particularly useful for analyzing and correlating vapor‐liquid equilibria in the critical region.
Heat transfer in liquid‐liquid spray towers
Authors: Greskovich E. J. , Barton Paul , Hersh R. E.
Published: June 2004

An experimental investigation of heat transfer rates in which were used three spray towers varying from 4 to 6 in. in diameter and 7 to 10 ft. in height, and distributor elements with hole sizes varying from 1/8 to 1/64 in. in diameter was carried out. The immiscible liquid system consisted of water and kerosene (normal boiling point range 395° to 490°F.). Volumetric heat transfer coefficients ranged from 100 to 3,600 B.t.u./(hr.)(cu. ft.)(°F.) and the overall film heat transfer coefficients ranged from 4 to 23 B.t.u./(hr.)(sq. ft.)(°F.). Height equivalent to a theoretical stage varied from 1 to 8 ft. Scale‐up correlations relating these rate data to operating variables were developed.
Drop formation at low velocities in liquid‐liquid systems: Part I. Prediction of drop volume
Authors: Scheele George F. , Meister Bernard J.
Published: June 2004

A correlation is presented for predicting the drop volume for injection at low velocities of one Newtonian liquid into a second stationary immiscible Newtonian liquid in the absence of surface active agents. The analysis, which is based on a two‐stage process of drop formation, predicts drop volumes within an average error of 11% for fifteen liquid‐liquid systems covering a wider range of variables than any previous study. Although the equation was tested primarily with mutually saturated liquids, if correctly predicted drop size for two systems where mass transfer was occurring.
The numerical solution of large systems of linear differential equations
Authors: Davison E. J.
Published: June 2004

In chemical engineering and process control, the numerical solution of large systems of linear, time‐invariant, differential equations must often be considered. Standard numerical techniques such as the Runge‐Kutta method usually require excessive computational time. Since often the time solution of only a few variables is desired in such large systems, a method has been developed to take advantage of this and allows the solution of large systems of differential equations to be obtained in an extremely fast and efficient manner. The basis of the method is to solve for the poles and zeros of the system and then to find the time solution in terms of these poles and zeros.
Kinetics of thiophene hydrogenolysis on a cobalt molybdate catalyst
Authors: Satterfield Charles N. , Roberts George W.
Published: June 2004

The intrinsic kinetics of the hydrogenolysis of thiophene on a cobalt molybdate catalyst were studied in a differential reactor with recirculation, at a total pressure of about 1 atm. and temperatures of 235° to 265°C. Retardation of the reaction by both thiophene and hydrogen sulfide was significant and the rate of thiophene disappearance was correlated by a Langmuir‐Hinshelwood type of kinetic equation. Hydrogenation of the butene intermediate was inhibited by both butene and hydrogen sulfide and the rate of this reaction was also described with a Langmuir‐Hinshelwood rate equation. The forms of the kinetic expressions obtained imply that the butene is not hydrogenated at the original desulfurization site.
Bubble driven fluid circulations
Authors: De Nevers Noel
Published: June 2004

Bubble driven fluid circulations are present in bubble columns, gas lifts, pool boiling, etc. Their mechanism is shown to be quite similar to the mechanism of natural covection but with much larger driving forces. These circulations are stable in many baffled systems but unstable and rapidly changing in size, shape, and orientation in unbaffled systems. The effect of these circulations in bubble columns is to lower holdup and vapor residence time, thus decreasing the mass transfer efficiency of the column.
Promotion of drop‐by‐drop condensation of steam from seawater on a vertical copper tube
Authors: Bromley L. A. , Porter J. W. , Read S. M.
Published: June 2004

A limited number of tests were made of promoters, their method of application, corrosion resistance, etc.

The best promoter found to date is tetrakis octadecyl thio silane (C18H37S)4Si which differs only in parafinic chain length from (C12H25S)4Si which was found to be one of the best promoters for drop‐by‐drop condensation by Blackman and Dewar (1, 2), Hampson (2, 3), and Osment (4, 5). These compounds are nontoxic.

The C18 compound appears to be superior to the C12 compound in that it is less volatile, lower melting (∼34°C), and appears to impart superior oxidation resistance to copper when adsorbed on clean oxide‐free metal.

Copper tubes can be rapidly cleaned in place by sulfur dioxide or hydrochloric acid in steam, or, if previously promoted by a thio silane, by treatment first with chlorine gas in steam.

The thio silanes may be rapidly applied as a 1% solution in octanoic acid injected into the sea‐water feed. The acid acts as cleaner and poor promoter, allowing the good promoter molecules to contact the metal tube.

The amounts of the best promoters required are in the parts per billion range.
Transient natural convection in a vertical cylinder
Authors: Evans L. B. , Reid R. C. , Drake E. M.
Published: June 2004

An experimental and analytical study is reported of transient natural convection in a vertical cylinder. For the experiments a cylinder was partially filled with liquid and subjected to a uniform heat flux at the walls. Thermocouples were used to measure the unsteady temperature field within the liquid; dye tracers were used to study flow patterns. Parameters that were varied included the test liquid (water‐glycerin mixtures), the liquid depth, and the wall heat flux. A range of Prandtl number from 2 to 8,000,L/Dratio from 1 to 3, and Grashof number from 103to 1011were studied, encompassing both laminar and turbulent flow regimes.

An analytical model was developed by dividing the system into three regions: a thin boundary layer rising along the heated walls, a mixing region at the top where the boundary layer discharges and mixes with the upper core fluid, and a main core region which slowly falls in plug flow. The temperature of the core fluid was assumed to vary in the vertical direction but not in the horizontal direction. Natural convection boundary‐layer equations were modified to allow for a temperature variation at the outer edge of the boundary layer. The model may be used with a step‐by‐step computational procedure to predict the temperature distribution in the fluid as a function of time for an arbitrary set of conditions. Results computed by using the model were in good agreement with the experimental data.
Mass transfer and wake phenomena
Authors: Magarvey R. H. , Maclatchy C. S.
Published: June 2004

The external velocity field associated with the fall of a single drop through a quiescent liquid phase is discussed. The field responsible for the transfer of vorticity from the point of generation to the disperse phase is assumed to be almost identical with the field that transfers mass from the drop interface. The stream surfaces associated with this field are made visible by means of dye trails. Since the field is not amenable to mathematical formulation, and since many reports appear in the literature concerning correlations between measurable flow parameters and the physical properties of the system, the field configurations relative to mass transfer mechanisms are considered qualitatively. The delineation of the flow patterns behind the drop gives some indication of the manner in which the external flow contributes to the transfer coefficients.
On certain unsteady torsional flows of simple fluids
Authors: Johns L. E.
Published: June 2004

This paper presents an investigation of the equations of motion to find the conditions under which these equations admit exact viscometric solutions for certain unsteady torsional flows of incompressible simple fluids. In general, for the cone and plane and the parallel disk geometries, curvilineal solutions do not exist for arbitrary members of the class of simple fluids; however, if the inertia terms can be neglected in the equations of motion, curvilineal solutions can be found for the complete class of simple fluids.
A composite phase plane for tubular reactor stability studies
Authors: Wang Frank S. , Perlmutter D. D.
Published: June 2004

A composite phase plane is introduced in order to describe geometrically the transients of a distributed parameter system with only one physical dimension. Its intrinsic features are discussed and compared with those of the ordinary phase plane. For the plug‐flow tubular reactor an equivalence is established between bounds on the reactor transients and the confinement of their projections on the composite phase plane. A constrained integration method is developed which enables one to find a region of stability for an adiabatic reactor, and a related technique is demonstrated for a nonadiabatic case. A hypothetical reactor system is analyzed numerically to illustrate the application.
Determination of the profile of a growing droplet
Authors: Halligan J. E. , Burkhart L. E.
Published: June 2004

The profile of a growing droplet was determined with a pressure balance which was similar to that derived by Laplace for the static droplet. An additional term was added to the balance to account for the pressure on the interface due to the motion of the fluid within the droplet. The entire pressure balance was then combined with differential equations describing the geometry of the droplet. Computed profiles compared favorably with those obtained experimentally.

An additional result was the definition of a parameter, f, indicating the importance of internal fluid motion on the shape of the profile. A method of estimating this parameter without solving the equations was developed.
Optimal control of a distillation column
Authors: Brosilow C. B. , Handley K. R.
Published: June 2004

Optimal feedback control has been implemented on a fifteen tray pilot scale rectifying column. The results show that excellent control is obtained in spite of major upsets in the feed flow rate and for large changes in the controller set point. Design and implementation costs for the optimal control system should be competitive with those for standard control systems.
The rates of evaporation of sprays
Authors: Dickinson Dean R. , Marshall W. R.
Published: June 2004

This paper reports a computational study of the evaporation rates of sprays of pure liquid drops having negligible velocity with respect to the air, and for drop velocities great enough to affect the evaporation rate. The principle parameters considered were the mean diameter and distribution of drop sizes in the initial spray, ratio of air to spray, initial temperature difference between air and spray, initial drop velocity, and air velocity.
Use of molecular shape factors in vapor‐liquid equilibrium calculations with the corresponding states principle
Authors: Leach J. W. , Chappelear P. S. , Leland T. W.
Published: June 2004

Calculation of fugacities of components in a gaseous or liquid solution directly from the corresponding states principle requires an improvement in the pseudo‐critical constants for the mixture. The derivation of the pseudo‐criticals must take into account deviations from the simple two parameter corresponding states principle which require additional parameters incorporated into the definition of the pseudo‐criticals. In this work parameters called molecular shape factors are introduced into the pseudo‐criticals. A generalized correlation for these shape factors is presented.

Use of the shape factors greatly improves the calculation of vapor‐liquid equilibrium ratios for nonpolar hydrocarbon mixtures with large differences in molecular size and shape. Excellent results are obtained both in the low pressure and in the retrograde region when the pseudo‐reduced properties of the vapor and liquid lie within the range of accurately known properties of a reference fluid and the reduced temperatures for each component is greater than approximately 0.6.
An analysis of oxygen absorption in a tubular membrane oxygenator
Authors: Buckles R. G. , Merrill E. W. , Gilliland E. R.
Published: June 2004

An analysis of oxygen absorption by blood flowing through a small oxygen‐permeable fiber in steady state laminar flow is presented. The rigidity and geometry of the fibers eliminate unpredictable shunting and distention, permitting a more detailed analysis of blood‐membrane factors than has previously been undertaken. The mathematical analysis treats the blood as a homogeneous, non‐Newtonian fluid with a reversible nonlinear oxygen sink (erythrocytes). The differential equations are solved numerically and the results of the parametric analysis are presented. The parameters that have a major influence on residence time necessary to obtain a specified oxygen content are the Grashof number, the concentration of hemoglobin in the blood, and wall Nusselt number, γ: γ = DLαL/DMαM In [1 + tm/R] where D = diffusion coefficient, α = Bunsen solubility coefficient, subscript L = liquid in tube, subscript M = tube material, R = inner radius of tube, tm = tube wall thickness.

Comparison of the experimental results to the model indicate that mixing due to the heterogeneous nature of blood is minimal and that the major limitation in oxygen absorption is the blood film. Means of reducing this resistance are discussed.
Convective diffusion in rotating disk systems with an imperfect semipermeable interface
Authors: Zeh Dale W. , Gill William N.
Published: June 2004

Solutions to the momentum and diffusion equations are obtained for rotating disk systems with an imperfect semipermeable interface, with direct application made to the reverse somosis or hyperfiltration process of salt water purification. The equations are solved exactly, and a new technique for solving the momentum equations is described. An approximate solution to the diffusion equation is also obtained which is also applicable to the energy equation, and is shown to be accurate for Prandtl and Schmidt numbers ≥ 1, for a wide range of interfacial mass transfer, for all wedge‐type flows as well as the rotating disk system.
A model for the prediction of velocity and void fraction profiles in two‐phase flow
Authors: Brown F. C. , Kranich W. L.
Published: June 2004

An experimental study of velocity and void‐fraction profiles has been carried out for the cocurrent two‐phase flow of both air and water, and air and glycerine‐water systems. The investigation was restricted to flow in a horizontal, 1 in. diam. tube with primary emphasis on the bubble flow regime. The assumptions which must be made to reduce the general equations of continuity, momentum, and energy to the forms appropriate for two‐phase flow are presented and the equations simplified for the case of no local slip. A model is proposed which allows the determination, by trial, of the two‐phase velocity and void‐fraction profiles. The profiles generated by the use of the model in conjunction with experimental sampling data are presented, the profile shapes are discussed, and their variations with Reynolds and Froude numbers and gas volumetric flow fraction are shown to be self‐consistent. The horizontal profiles are found to be in fair agreement with those predicted from Levy's mixing length theory. A correlation scheme is outlined which, supplemented by data over wider ranges of operating conditions, would serve as a method for estimating pressure drops in two‐phase flow.
Analysis of steady state shearing and stress relaxation in the Maxwell orthogonal rheometer
Authors: Bird R. Byron , Harris Everette K.
Published: June 2004

A nonlinear, integral viscoelastic model is used to predict the stresses in the Maxwell orthogonal rheometer. The resulting expressions indicate that the instrument yields data on material functions not heretofore measured, and also show how the data may be analyzed to get the complex viscosity. Expressions are given for stress relaxation after cessation of shearing. Some experimental data are analyzed to give model parameters.
Hydrodynamics of wave flow
Authors: Berbente C. P. , Ruckenstein Eli
Published: June 2004

In this paper a method for obtaining periodical solutions of the nonlinear equations of motion is proposed. The method is applied to the case of a falling liquid film in wave motion. It consists in a triple series expansion; the first is a Taylor expansion, with respect to the distance y1 from the free surface; a second one, representing the periodicity condition, is a Fourier expansion with respect to the variable z  k(x—ct), and a third one is a Taylor expansion with respect to the amplitude 2iϕ1. The calculation of the different coefficients is made easy by the fact that the algebraic equations obtained are linear and do not simulataneously contain all the unknowns. This allows the performance of the computation step by step in increasing order of the powers of ϕ1. The periodicity conditions allows the determination of all physical quantities as functions of one of them. The amplitude |2iϕ11| was selected as the parameter.

The existence of a dimensionless quantity for the wave flow is outlined. Arguments are adduced in support of the fact that the amplitude| 2iϕ1| depends only on ψ and a universal curve |2iϕ1| vs. ψ is plotted on the basis of experimental data. Theoretical equations for the wave length, the wave velocity and the film thickness as a function of ψ are established. There is good agreement between the theoretical equations and experiment.
Feedforward and dynamic uncoupling control of linear multivariable systems
Authors: Greenfield Gaylord G. , Ward Thomas J.
Published: June 2004

A modified V‐form method is presented for the feedback dynamic uncoupling and feedforward control analysis of linear constant coefficient multivariable systems with the control objective of making two or more outputs invariant. Suitable feedback control degrees of freedom remain for a subsequent and independent primary feedback control analysis of each uncoupled subsystem. This method is also compared with the alternative structural analysis method of the authors.
Two phase friction factor for para‐hydrogen between one atmosphere and the critical pressure
Authors: Rogers John D.
Published: June 2004

The Martinelli model for pressure drop in flowing two‐phase systems has been examined in detail for para‐hydrogen from 1 atm. to its critical pressure. Amethod for obtaining the Martinelli Φ term, two phase friction factor, at intermediate pressures is presented. Φ2 can be expressed as a function of pressure and quality. The Martinelli β term, ratio of actualvapor or gas area to an idealized cylindrical area, is found to vary greatly and to indicate first an increase in gas‐liquid interface to gas volume ratio and then a decrease with increasing pressure. Some experimental data are examined in light of this development.
Residence time distribution of the dispersed phase in a spray column
Authors: Letan Ruth , Kehat Ephraim
Published: June 2004

A dye tracer technique was utilized to measure the residence time distribution of the drops in a spray column, operating with a dispersed or a dense packing of drops, for a wide range of flow rates, in a 15 cm.in diameter, 150 to 160 cm. long column proper.

For dispersed packing of drops and for flow rates below the onset of coalescence, the flow of the drops was approximately plug flow, with a variance of the residence time distribution of 0.095. For flow rates above the onset of coalescence within the column, the variance increased sharply to 0.55 and decreased at higher flow rates.

For dense packing of drops the variance of the residence time distribution was in the range of 0.1 to 0.5. This variance is attributed to the effect of bypassing water and kerosene near the wall of the column. A mathematical model based on this effect showed reasonable fit with the experimental results. This model predicts an approach to plug flow of the drops for large diameter columns.
The synthesis of system designs. II. Heuristic structuring
Authors: Masso A. H. , Rudd D. F.
Published: June 2004

The use of heuristic structuring strategies in the development of computer programs for the synthesis of process designs is examined. By the employment of selection weights which are adjusted as experience is gained from past successes and failures, the computer is able to learn the sequence of structuring decisions which leads toward the optimal process design. The computer can develop competence in the synthesis of systems in a limited area of technology.
Permeation through plastic films
Authors: Li N. N. , Long R. B.
Published: June 2004

Data are presented on the solubility in and permeation through polyolefin films of a number of gases and liquids. The permeation rates are found to be dependent on the type of film, the concentration and the temperature. A classical diffusion model explains the permeation mechanism and other relations serve to correlate the data.
Structuring design computations
Authors: Christensen J. H. , Rudd D. F.
Published: June 2004

Process design computations are represented by directed graphs whose edges correspond to streams of information flow between computational units. Algorithm I‐R extends existing algorithms for finding the minimal sized blocks of units between which no recycle exists. Algorithm II‐R orders the sequence of unit computations within a block to minimize the number of recycle parameters. Algorithm III‐R uses the concept of indexing to order computations which evade algorithm II‐R. This work is directed toward the evolution of efficient programs for computer‐aided process design.
Use of electrochemical techniques to study mass transfer rates and local skin friction to a sphere in a dumped bed
Authors: Jolls Kenneth R. , Hanratty Thomas J.
Published: June 2004

Electrochemical techniques are developed to study the details of the flow around a single particle in a packed bed. Initial work has been done with a dumped bed of 1 in. spheres. Results are presented on the variation of the mass transfer coefficient and the shear stress around the surface of one of the spheres, the overall mass transfer rates to a sphere in a bed of inert spheres, and the effect of Reynolds number on the local mass transfer coefficient and the shear stress.
Mass transfer limitations in a trickle‐bed reactor
Authors: Satterfield Charles N. , Pelossof A. A. , Sherwood Thomas K.
Published: June 2004

The hydrogenation of alpha‐methylstyrene to cumene at 20 to 50°C. was studied experimentally with a trickle‐bed reactor comprising a single vertical column of spherical porous palladium‐on‐alumina catalyst pellets. Other studies with powdered catalyst and studies in which catalyst pellets were swirled in a reactor allowed the intrinsic kinetics and effectiveness factor of the catalyst pellets to be determined. At 50°C. the reaction rate in the trickle‐bed was about one‐half of that in the absence of mass transfer limitations in the outside liquid film. The effectiveness factor of the pellets alone at 50°C. was 0.0057, and the tortuosity factor was 7.5. Experimental results are compared with four theoretical models for tricklebed reactors and criteria are presented for estimating whether mass transfer through the outside film is a significant resistance in an industrial trickle‐bed reactor.
Turbulent, high Schmidt number, entrance region mass transfer in annuli
Authors: Cermak James O. , Beckmann Robert B.
Published: June 2004

Entrance region and fully developed mass transfer from the inner core of annuli was investigated for a fully developed velocity profile and a Schmidt number of 760. Constant wall concentration was the satisfied boundary condition of the inner core.

The ranges of parameters investigated were 21,400 to 75,600 for Reynolds number, 0.164 to 0.741 for the annulus diameter ratio, and 0.018 to 3.85 for the length to hydraulic diameter ratios.

Experiments were performed in an open water flow loop. Mass transfer coefficients were obtained from weight loss measurements of benzoic acid life saver elements of various diameters and lengths. These elements were assembled as an integral part of the inner core of the annulus. Concentricity was maintained by a tensioning device.

The local Sherwood number is found to be significantly affected by the annulus diameter ratio, Reynolds number, and the length to hydraulic diameter ratio. A correlation is developed which predicts 93% of the data used for its development to within ± 10%.
Free volume theory for viscosity of simple nonpolar liquids. Part II. Mixtures
Authors: Gubbins Keith E. , Tham M. J.
Published: June 2004

The free volume equation for liquid viscosities is generalized to multicomponent mixtures. No experimental mixture data are needed in order to use the correlation. Calculated viscosities for liquid mixtures composed of molecules which approximately obey the Lennard‐Jones 6, 12 potential law show very good agreement with experimental data for eight binary systems.
The laminar boundary layer on a moving continuous flat sheet immersed in a non‐Newtonian fluid
Authors: Fox V. G. , Erickson L. E. , Fan L. T.
Published: June 2004

The laminar boundary layers on a moving continuous flat surface in non‐Newtonian fluids characterized by the power law model are investigated using exact and approximate methods. Both pseudoplastic and dilatant fluids are considered. Numerical solutions of the boundary‐layer equations are obtained for values of the parameter n in the power law model ranging from 0.1 to 2.0. An integral solution of the momentum equation, which can be used to obtain values of the dimensionless shearing stress that are in good agreement with the exact values, is developed. An integral solution to the energy equation is also presented.
The change in pore size distribution from surface reactions in porous media
Authors: Schechter R. S. , Gidley J. L.
Published: June 2004

When a porous solid is penetrated by a reactive fluid which changes the pore geometry, the macroscopic properties of that porous material may be greatly changed. A model is proposed in which the matrix is visualized as being a number of short cylindrical pores dispersed randomly throughout the solid. The change in the distribution of these cylindrical pores is then represented by a integrodifferential equation which is solved for two special cases.

The evolution of the pore size distribution is determined by the particular way in which the solid‐liquid boundary takes place. The case considered here is that of a surface reaction which dissolves the solid thus continuously enlarging the pores. The rate of reaction is calculated theoretically using a laminar flow diffusion model and this growth rate expression is then taken as the basis for numerical calculations relating to the action of dilute hydrochloric acid on limestone.

A comparison is made with experimental results and it is found that the model behaves in much the same way as the real system although the observed rate of pore growth was two to three times that predicted by the diffusion model. Several possible explanations for this discrepancy are being tested.

An exact solution of the integrodifferential equation for highly retarded reaction rates has been found with the change in permeability being given in terms of the change in porosity. This result will permit a prediction of the stimulation that can be achieved in acidizing oil wells with retarded acids.
Mathematical analysis of bubble dissolution
Authors: Duda J. L. , Vrentas J. S.
Published: June 2004

A perturbation series solution is derived for isothermal bubble dissolution and bubble growth from an initially finite size. The new solution is superior in several aspects to the quasi‐stationary and quasi‐steady state approximations derived previously. The accuracy and range of validity of the new results are investigated by comparison with finite‐difference solutions of the equations governing bubble growth or dissolution. In addition, previous numerical solutions of the problem are compared to the finite‐difference results of this study.
The experimental determination of the volumetric properties and virial coefficients of the methane‐ethylene system
Authors: McMath H. G. , Edmister W. C.
Published: June 2004

An apparatus was constructed for making isochoric measurements of P‐V‐T properties. Experimental compressibility factors were obtained and are presented for methane, ethylene, and four intermediate mixtures at 60, 40, and 20°F., with pressures from 260 to 2,220 lb./sq.in.abs. Second and third virial coefficients and interaction virial coefficients were determined from the data. The compressibility factors and the virial coefficients are compared with the Benedict‐Webb‐Rubin equation of state, applied in its original form and in a recent generalized form.
Viscoelastic jet stability
Authors: Kroesser F. William , Middleman Stanley
Published: June 2004

The breakup of a low speed horizontal jet is investigated. Weber's theory for the Newtonian jet is extended to a linear viscoelastic fluid. The theory predicts a dependence of breakup length on the elasticity number. Breakup lengths are measured for low concentration solutions of polyisobutylene in tetralin. Two molecular weights, several concentrations, and five capillary diameters were studied. A single correlation is obtained for all data which gives the breakup length as a function of the elasticity number, and the parameters of Weber's theory. At constant values of the Ohnesorge number and Weber number, the breakup length decreases with increasing elasticity number. The effect of the length of the capillary is studied. At large elasticity numbers short tubes give rise to slightly shorter breakup lengths than long tubes under identical flow conditions.
The aqueous phase oxidation of cyclohexane using gamma radiation
Authors: Ashline Ronald C. , Von Berg Robert L.
Published: June 2004

A study was made of the radiolytic oxidation of cyclohexane in aqueous solution by using cobalt 60 gamma radiation. In the presence of dissolved oxygen gas the reaction proceeds irreversibly with the formation of a number of oxidation products. Those identified were cyclohexanol, cyclohexanone, and hydrogen peroxide. Trace quantities of carbon dioxide were also detected in the liquid phase. Using a constant dose rate of 15 × 104 rad./hr. in all runs, radiation yields were G(C6H11OH) = 0.49, and G(C6H10O) = 1.08. When molecular oxygen was excluded from the system, neither cyclohexanol nor cyclohexanone was formed on irradiation. A simplified kinetic model based on competition by the various solutes in the system for a single primary radical species produced by radiolysis of the solvent molecules is developed. Results generated using the mathematical model are compared with the experimental data. Excellent agreement between the observed and computed trends is noted at radiation doses up to 50 × 104 rad.
Optimal control of tubular reactors. Part II. Jacketed configuration with step feed disturbance
Authors: Chang K. S. , Bankoff S. G.
Published: June 2004

The optimal unsteady control of a jacketed tubular reactor with and without heat generation due to chemical reaction in response to a step disturbance in the feed stream concentration is computed. More rigorous control action was found to be necessary for the case with heat generation than without heat generation. Convergence of the method was also investigated with fixed and free final time.
Material and energy balance computations, E. J. Henley and E. M. Rosen, John Wiley, New York, 577 pages
Authors: Kranich W. L.
Published: June 2004

No Abstracts.
Model simulation of adiabatic continuous flow stirred tank reactors
Authors: Keairns D. L. , Manning F. S.
Published: June 2004

Manning, Wolf, and Keairns' model for continuous flow‐stirred tank reactors has been extended to include adiabatic as well as isothermal operation. The adiabatic, steady state yield of a continuous flow‐stirred tank reactor was measured experimentally using the second‐order, homogeneous, exothermic reaction between sodium thiosulfate and hydrogen peroxide. Model predictions of overall tank yield agreed closely with the data, thus verifying the applicability of this model to explain the effects of operating variables such as impeller size, impeller type, agitator speed, feed location, feed concentration, and flow rates.
Thermally induced solid state polycondensation of nylon 66, nylon 6‐10 and polyethylene terephthalate
Authors: Chen F. C. , Griskey Richard G. , Beyer G. H.
Published: June 2004

The mechanism of solid state polycondensation has been subjected to a fundamental analysis. Equations were formulated for combined diffusion and chemical reaction for two separate situations. One was for solid state polycondensation in polymer flakes or chips. The other dealt with polymer powders. The resultant solutions related molecular weight changes to rate functions. A technique for deriving the rate functions from experimental data is described.

Solid state polycondensations were then studied for nylon 66, nylon 6‐10, and polyethylene terephthalate. These data which ranged from 120 to 200°C. were tested with various mechanisms. The most appropriate one was found to be that developed in the present work. Chemical reaction was found to be the rate controlling step in solid state polycondensation in nylon 66, polyethylene terephthalate, powders of nylon 6‐10 and larger particles of nylon 6‐10 at and above 160°C. Diffusion of byproduct through the solid was the rate controlling step for larger particles of nylon 6‐10 at temperatures below 160°C. Thermograms of nylon 6‐10 indicated morphological changes which possibly influenced the behavior of the larger nylon 6‐10 particles. The Arrhenius relation was fitted to the situations where chemical reaction controlled.
Axial dispersion with time variable flow in multiphase systems
Authors: Gill William N.
Published: June 2004

A theory has been developed for heat or mass transfer between phases which may have unsteady time dependent velocity fields. The configuration analyzed involves two concentric tubes, but the analysis can be extended to more than two phases, or streams, and to noncylindrical cross sections. For the configuration considered, the dispersion coefficient is found from first principles.

It is noteworthy that the dispersion model given by Equation (15) or (63) and (64), which is consistent with the basic continuum model of Equations (8) and (9), is based on the superficial velocity rather than the interstitial velocity. This strongly suggests that experimental observations on packed beds, or other multiphase systems, should be interpreted on the basis of um, the superficial velocity, rather than the interstitial velocity which has been used often in the past.