bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of thiophene hydrogenolysis on a cobalt molybdate catalyst
Authors: Satterfield Charles N. , Roberts George W. 
Published: June 2004

AbstractThe 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

AbstractBubble 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

AbstractA 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

AbstractAn 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractThe 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

AbstractOptimal 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

AbstractThis 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

AbstractCalculation 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

AbstractAn 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

AbstractSolutions 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

AbstractAn 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

AbstractA 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

AbstractIn 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

AbstractA 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractData 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

AbstractProcess 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

AbstractElectrochemical 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

AbstractThe 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

AbstractEntrance 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

AbstractThe 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

AbstractThe 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.