bluuebunny/crossref_metadata_2025 huggingface dataset:
An experimental design strategy for distinguishing among rival mechanistic models an application to the catalytic hydrogenation of propylene
Authors: Hunter W. G. , Mezaki R.
Published: March 2009

Box and Hill's method was applied to discriminate between two mechanistic models for the catalytic hydrogenation of propylene. A sequential experimental design procedure, this method makes use of a discrimination criterion obtained from information theory.
Recent developments in plasma jet technology
Authors: Kubaisek G. R. , Gauvin W. H.
Published: March 2009

This article is an up‐to‐date survey of the field of plasma jet technology. Its intention is to make available the latest information about the characteristics, limitations and applications of plasma generating devices, particularly in the field of chemical processing.

The uses of plasma jet in the aerospace field, and in material processing and fabrication are briefly reviewed. The chemical applications discussed include the syntheses of acetylene, cyanogen, nitric oxide, as well as various carbides and nitrides.
Wall mass transfer in liquid‐fluidized beds
Authors: King D. H. , Smith J. W.
Published: March 2009

Ionic mass transfer coefficients between the wall and a liquid fluidized bed of 0.043 inch lead glass spheres have been measured using the diffusion controlled reduction of ferricyanide ion at a nickel cathode.

The coefficients obtained are correlated in terms of the dimensionless j factor and are compared with dissolution mass transfer results by this author and with a recent liquid fluidized bed heat transfer study(1) with these same particles. It is concluded that in the dissolution study either mechanical erosion or roughness effects or both were present. No analogy was found to exist between overall heat and mass transfer in a liquid fluidized bed in which there is a large difference between the Schmidt and Prandtl numbers because the dominant resistance is different for the two cases.
The thermal theory and the plate efficiency
Authors: Ruckenstein E. , Smigelschi O.
Published: March 2009

An experimental study concerning the plate efficiency is performed in bubbling regime and in foam regime, by means of a single tray column. Two mixtures have been used. One of them, the system cyclohexane‐toluene was selected since its surface tension is practically independent of concentration, while the other system (methanol‐water) was selected because its surface tension depends strongly on concentration.

For the bubbling regime, experiments lead to the conclusion that the plate efficiency depends in the same manner for both mixtures on composition (the curves of efficiency vs. composition present a weak maximum) though the Marangoni effect does not occur for the first system and has favorable conditions of occurrence for the second system.

For the foam regime the efficiency is practically equal to unity for all compositions.

In the theoretical part of the paper several possible mechanisms of the rectification process are discussed. One is based on the diffusional model derived from the classical theory. Three other equations are based on the assumption that vaporization in the bulk of the liquid occurs too. A criterion for the occurrence of this thermal effect is given.

A possible explanation of the non‐occurrence of the thermal effect in cases for which the above mentioned criterion leads to a contrary conclusion, is also included.
Modelling polymerization reactors with applications to optimal design
Authors: Ray W. H.
Published: March 2009

Using generating functions, models for polymerization reactors are developed without using kinetic approximations. One of the models is then used for the optimization of a series of tank reactors in which free radical polymerization is taking place. It is found that peak‐seeking methods are a convenient and efficient method of optimizing such systems. Curves showing “optimal” design alternatives are generated for the simple example treated.
Holdup and flooding in air liquid mixing
Authors: Rushton J. Henry , Bmbinet Jean‐Jacques
Published: March 2009

The amount of flowing air held up, or retained, under the surface of water and corn syrup solutions was measured in cylindrical tanks of different sizes using turbine type mixing impellers. Holdup is frequently used as an index of the effectiveness of gas‐liquid contacting in adsorption or stripping operations; it can be correlated with air flow rate and power input as follows

h = a(PT/V)bFc

where h is the holdup of air in ft. per ft. of ungassed liquid, a, b, and c, are constants, (PT/V) is the total power supplied by the impeller and air per unit volume, and F is the superficial velocity of the air. Values of a and b vary with tank size. The effect of liquid viscosity is pronounced but not amenable to simple correlations with the constants.

Limits of operation to prevent flooding are defined as functions of impeller power and air flow.
Non ideal solutions: Excess free energy and activity coefficients from total pressure measurements
Authors: Ramalho R. S. , Delmas J.
Published: March 2009

A numerical method for calculating excess free energies and activity coefficients for binary systems, from total pressure measurements, is developed, which is well adapted to digital computation. The proposed method is shown to be superior to most methods now available in the literature.
Drag coefficients of evaporating spheres in a turbulent air stream
Authors: Clamen A. , Gauvin W. H.
Published: March 2009

A study was made to determine the effect of mass transfer on the drag coefficients of freely‐moving aerodynamically smooth spheres, accelerating in a co‐current turbulent air stream. The particles consisted of celite impregnated with liquid sulphur dioxide and varied in diameter from 0.184 to 0.989‐inch. Accurate time‐distance data were obtained with a new particle‐tracking technique which allowed the quantitative measurement of drag coefficients for relative turbulence intensities varying from 5 to 30%.

The range of Reynolds numbers studied was from 2100 to 29,800, which, because of the effect of free‐stream turbulence, forms a part of the super‐critical flow regime. The results have thus been compared with the previously reported drag data for solid non‐evaporating spheres in a similar flow region.

Mass transfer was found, in general, to decrease the super‐critical drag on a sphere and to reduce the influence of relative turbulence intensity. This alteration in momentum transfer is probably due to a reduction in the skin friction and to a pressure increase in the wake of an evaporating sphere.
Particle retardation in vertically oscillating fluids
Authors: Houghton Gerald
Published: March 2009

An analytic expression has been deduced for the ultimate velocity of a free particle in a vertically oscillating fluid by evaluating asymptotic forms of Floquet's solution to the Mathieu equation arising from the nonlinear Langevin equation describing the particle‐fluid interactions. Using general Mathieu theory it has been rigorously demonstrated that directional particle motion in a gravitational field can be retarded by sinusoidal fluid oscillations when the particle‐fluid drag law is of square form. The earlier Rayleigh‐Ritz approximation (Houghton 1966) for the retarded particle velocity is shown to be in good agreement with the results of Mathieu theory, as summarized in graphical form.
Thermodynamic functions for 3‐fluoropropene
Authors: Bryce H. W. , Lielmezs J.
Published: March 2009

Thermodynamic functions Cp°, S°, (H°‐H0°)/T, —(F°‐H0°)/T have been calculated for 3‐fluoropropene in the ideal gas state from 298.15° to 800°k. at 1 atm. pressure. The restricted rotational contribution has been treated by the conventional method of Pitzer and Gwinn.
Behavior of gas bubbles in vertically vibrating liquid columns
Authors: Rubin Eliezer
Published: March 2009

A theoretical analysis of the behavior of gas bubbles in vertically vibrating liquid columns is presented. The theoretical approach predicts the depth in liquids at which the downwards force, due to vibrations, acting on single bubbles just balances the buoyancy force, i.e. the depth of no net movement of given bubbles. Theoretical results predicting the direction of movement of bubbles were obtained for various diameters over a wide range of frequencies, amplitudes, liquid viscosities and densities. Agreement with published experimental work is good.
Distribution of lengths in the breakage of fibres or linear polymers
Authors: Goren Simon L.
Published: March 2009

The distribution of fiber or polymer lengths during breakage is considered. It is shown that under certain conditions the distribution of lengths is given by a self‐preserving form which is independent of the initial distribution and is not explicitly dependent on time. Some self‐preserving distributions are calculated. The theory is compared with an experiment on the breakage of glass fibres caused by milling.
Quasilinearization technique for solution of boundary layer equations
Authors: Lee E. S. , Fan L. T.
Published: March 2009

Owing to the split boundary conditions, there arise many difficulties in solving numerically the nonlinear equations describing the boundary‐layer flow. It is shown in this paper that the quasilinearization technique is a useful tool for solving the ordinary differential equations, which are obtained from the boundary layer equations through a similarity transformation. With very approximate initial guesses, only four to six iterations are needed to obtain a five digit accuracy.
An improvement on the martinelli analogy
Authors: Wilson N. W. , Medwell J. O.
Published: March 2009

The forced convection heat transfer phenomena are predicted over a wide range of Reynolds and Prandtl numbers for a circular pipe. The analogy method used by Martinelli is improved by the use of the van Driest velocity distribution in Lyon's integral approach.
Flow of suspensions in pipelines(Part 2: Two Mechanisms of Particle Suspension)
Authors: Shook C. A. , Daniel S. M. , Scott J. A. , Holgate J. P.
Published: March 2009

The distribution of sand and nickel particles with height in a horizontal channel of rectangular cross section has been measured and eddy diffusivities have been computed from these measurements. Turbulent suspension of particles appeared to occur where the concentration of solid particles was low, the particle diameter was small (< 0.2 mm.) and the ratio of the settling velocity of the particles to the friction velocity of the flow was less than 0.2. Where these criteria were not satisfied, concentration profiles were observed to deviate significantly from the shape associated with turbulent suspension. These deviations are attributed to the effect of particle interactions investigated by Bagnold.
Solve at extraction in an air‐pulsed packed column
Authors: Baird M. H. I. , Gloyne A. R. , Meghani M. A. N.
Published: March 2009

A novel type of extraction column has been constructed in which liquid pulsations are produced without the need for any mechanical moving parts. The factors governing the frequency and amplitude of the pulsations are discussed briefly. The effects of pulsation upon the extraction of acetic acid from kerosene by water in a packed column have been measured. The pulsations increase the number of transfer units by as much as threefold, a result similar to the observations of previous workers who used conventional pulsators having moving parts.
Dynamic response of a double effect evaporator
Authors: Andre H. , Ritter R. A.
Published: March 2009

The open loop dynamic response of a laboratory scale double effect evaporator has been adequately described by a simple mathematical model based on the unsteady state material and energy balances associated with the various elements of the system. Excellent agreement has been achieved between the experimentally determined response of the evaporator to large disturbances in steam rate and feed rate and the predicted response based on the digital computer solution of the non linear model.
Motion of continuous surfaces through stagnant viscous non‐Newtonian fluids
Authors: White James Lindsay
Published: March 2009

An analysis is given of the hydrodynamics and drag of a rigid sheet moving through a stagnant non‐Newtonian fluid. The methods of boundary layer theory are applied and it is shown that a ‘similarity’ transformation is sometimes possible. The effect of the apparent viscosity on the velocity field and drag is discussed and detailed solutions for different non‐Newtonian viscosities are obtained by integral momentum methods. The problem of drawing a cylinder through a non‐Newtonian fluid is also discussed.
The ratio of terminal velocity to minimum fluidising velocity for spherical particles
Authors: Bourgeois P. , Grenier P.
Published: March 2009

The analogy between the states of a particle falling at its terminal velocity in a fluid and that of a particle in a bed, at incipient fluidization by the same fluid, suggests the possibility of a correlating minimum fluidizing and terminal velocities and of predicting the minimum fluidizing velocity. A semi‐theoretical curve has been obtained, relating (Ret/Remf) to Fn = gpF (rHS – rHF) d3/μ2 and it has been compared with new experimental data collected for this purpose in the range 103<Fn<108. Analytical expressions for (Ret/Remf) are proposed.
Dependence of electrostatic charging currents on fluid properties
Authors: Goodfellow H. D. , Graydon W. F.
Published: March 2009

The dependence of the electrical charging of hydrocarbons on the chemical nature of non‐hydrocarbon additives has been investigated. An improved apparatus and technique allowed the authors to obtain data for new fluid systems over a wide range of solution conductivities and flow velocities. Currents and voltages have been measured from insulated stainless steel tubes, for different concentrations of polar species in hydrocarbon solutions, for Reynolds numbers of 1800 to 35,000.

Recent electrification theories explain the charging process on the basis of a diffusion‐controlled process. The magnitudes of the charging currents can be predicted using the usual mass transfer analogies. Experimental results, obtained for different polar additives studied, agreed with the theory. The sign of the measured current is not predicted theoretically. Potentials of both signs are observed. The particular sign obtained seems to be determined by the chemical nature of the polar additive. Different additives of similar chemical structure all give one sign.
The Electrolytic “Sintering” of Nickel Powder
Authors: Henderson I. H. S. , Ladan S. G.
Published: March 2009

Adherent and coherent deposits of nickel sponge similar to sintered nickel may be made from sulphate, chloride, fluoborate or sulphamate nickel plating solutions containing nickel powder in suspension, providing the concentration of free acid is maintained sufficiently high to inhibit co‐depesition of Ni(OH) In nitrate solution, cathodic reduction of nitrate and deposition of Ni(OH)2 predominates.
On the relation between state and adjoint variable initial conditions in optimum control theory
Authors: Latour Pierre R.
Published: March 2009

The algebraic relation between state and adjoint variable initial conditions for time‐optimum control of a particular second order linear system is reported. The relation between adjoint initial conditions and switching time suggests that difficulties might arise when boundary‐value search methods are employed to solve two‐point boundary‐value problems. These analytical results support the conclusions in a recent paper by Paynter and Bankoff.
Diffusion in binary liquid mixtures at infinite dilution
Authors: Lusis M. A. , Ratcliff C. A.
Published: March 2009

A correlation is presented for the mutual diffusion coefficient in a binary liquid system at infinite dilution. It has several advantages over previous correlations, and is recommended for diffusion in organic solvents. Some special cases where empirical correlations should be used with caution are discussed briefly.
Reactor dynamics and molecular weight distributions: Some aspects of continuous polymerisation in tubular reactors
Authors: Cnitron‐Cordero R. , Mostello R. A. , Biesenberger J. A.
Published: March 2009

A study was made of the effect of residence time distribution and thermal nonuniformities on molecular weight dispersion in continuous nonchain and chain polymerizations, respectively. The analyses were conducted with the aid of the assumption of microsegregation, which facilitated and unified the computational approach.

Holdback was examined and found to be a good criterion for characterizing the importance of residence time distribution. Power‐law flow index was found to have a direct effect on molecular weight dispersion in isothermal nonchain polymerizations as well as an indirect influence in chain polymerizations via its role as a parameter for thermal sensitivity.

It was concluded that the isothermal, segregated, continuous stirred tank reactor has a greater effect on molecular dispersion in nonchain‐type polymerizations than the worst isothermal tubular reactor, as correctly predicted by holdback, and temperature nonuniformities have a profound influence on molecular dispersion in chain‐type polymerizations.
Interpretation of methane adsorption on activated carbon by nonisothermal and isothermal calculations
Authors: Lee Robert G. , Weber Thomas W.
Published: March 2009

Experimental breakthrough curves for methane absorption on activated carbon are analyzed using isothermal and nonisothermal models. Interaction of heat and mass transfer effects vary from being almost negligible to being quite pronounced. Some rather large radial temperature gradients were measured in the bed. In spite of these, the fit of the experimental data to the nonisothermal model is reasonably good. Stability problems in the nonisothermal solution are discussed.
Stereophotogrammetry in particle‐flow investigation
Authors: Reddy K. V. S. , Van Wijk M. C. , Pei D. C. T.
Published: March 2009

Stereophotogrammetry was used for the first time to measure the local particle velocity vector and its turbulent components in two‐phase solid‐gas flow in a 10 cm. I.D. vertical pipe. From the image counts on the stereophotographs, it has also been demonstrated that the stereophotogrammetry could be used for the direct determination of the radial concentration distribution of the particles in the pipe.
The effects of changes in problem parameters on chemical equilibrium calculations
Authors: Smith W. R.
Published: March 2009

A simple method is described for evaluating the first order changes in calculated chemical equilibrium compositions resulting from changes in the problem parameters of temperature, pressure, initial reactant compositions, and standard free energy data for the species. It may be used to calculate the first order derivatives of the equilibrium mole numbers with respect to the problem parameters, thus indicating the solution's sensitivity to small changes in these values. Using the temperature and pressure derivatives and appropriate data for the species, all first order thermodynamic derivatives of the equilibrium mixture properties may be calculated. Finally, surveys may be performed of the equilibrium system for ranges of the problem parameters. The technique involves the solution of a set of m + ϕ linear equations, where m is the number of elements and ϕ the number of phases.
Longitudinal gas dispersion in transitional and turbulent flow through a straight tube
Authors: Flint L. F. , Eisenklam Paul
Published: March 2009

Longitudinal dispersion data are reported for a straight tube (internal dia. 1¼′ (2.77 cm)). Three binary gas systems were examined over the regime 3 × 102 < Re < 104 with special emphasis on the transition from laminar to turbulent flow. Effect of Schmidt number is studied in detail over the transition regime, and practical variation with Sc for the lower turbulent regime is compared with the predicted effect based on existing theories of turbulence. In the laminar regime results are reported which diverge from Taylor's theory at Re lower than the normally accepted value for the onset of turbulence.
Structural properties of packed beds — A review
Authors: Haughey D. P. , Beveridge G. S. G.
Published: March 2009

Some structural properties of packed bed systems on both the local and overall scales which are available in the literature and of interest in chemical engineering applications are discussed. Regular and random packings of uniformly sized spheres are initially analyzed as a basis for the later examination of the more general case of random packed beds containing particles of various sizes and shapes, with or without restraining surfaces.
Mixing in anchor agitated vessels
Authors: Peters D. C. , Smith John M.
Published: March 2009

Flow patterns and velocity profiles have been studied in anchor agitated vessels. The flow paths around the mixer blade in a Newtonian fluid may be characterized satisfactorily in terms of the blade tip Reynolds number and the blade width/wall clearance ratio. Calculations of the dispersion produced by the blade within a horizontal plane are not in agreement with experimentally determined (and therefore three‐dimensional) mixing times. This suggests that the vertical secondary flow is the more important mixing mechanism. Such vertical flows are shown to be more pronounced in visco‐elastic systems and the horizontal plane velocity profiles are substantially modified. A mechanism is suggested for this.
Generalized polynomial programming
Authors: Blau Gary E. , Wilde Douglass J.
Published: March 2009

Conventional design procedures use physical reasoning to construct equations describing the system. To find the optimal design for some specified performance criterion, it is desirable to change these equations into inequalities so that generalized polynominal programming, a highly nonlinear optimization technique, can be used. For illustration, a chemical reactor system optimal design problem with 11 variables and 8 constraints is formulated as an equality constrained optimization problem, then transformed into an inequality constrained generalized polynominal program and finally solved on the computer.
A phenomenological classification of catalyst behavior
Authors: Wojciechowski H. W. , Juusola J. A. , Downie J.
Published: March 2009

A system of catalyst classification is proposed. Nine classes of catalyst aging behavior are suggested based on the instantaneous and cumulative effects predicted by the time‐on‐stream theory of catalyst decay (3).
Analysis of stratified laminar flow of immiscible liquids in circular and non‐circular pipes
Authors: Achutaramayya G. , Sleicher C. A.
Published: March 2009

A numerical analysis has been made of laminar stratified flow of two immiscible Newtonian liquids in circular and certain non‐circular pipe configurations. Solutions are given far viscosity ratios of 10, 100, and 1000 and for various volumetric flow rate fractions. Five pipe configurations are studied. In each case volumetric flow rate factors and power reduction factors are computed. It is shown that the circular pipe is the best pipe configuration for the two‐phase flow having a viscosity ratio of about 10 or less. A flat bottomed pipe configuration is found to give higher volumetric flow rate factors as well as higher power reduction factors than the circular pipe when the viscosity ratio is about 100 or more.
Suspension of solids by bubble agitation
Authors: Narayanan S. , Bhatia V. K. , Guha D. K.
Published: March 2009

Using fundamental aspects of the fluid mechanics of a single particle, a relation for the velocity of liquid necessary to suspend solid particles in a shallow depth column is derived. This liquid velocity is developed by the movement of the gas bubbles inside the column with the potential energy dissipated by the bubble during its ascent taken as the gain in the kinetic energy of the liquid. This energy brings about sufficient liquid motion to suspend the particles. The corresponding superficial gas velocity to suspend all the particles present in the column is theoretically estimated and compared to experimental values of superficial gas velocities obtained for various solids concentrations. A set pattern of deviation is observed, and empirical correlations are suggested for predicting the superficial gas velocity to suspend a given amount of solid particles in liquid.
Theoretical patterns of selectivity in aging catalysts with special reference to the catalytic cracking of petroleum
Authors: Campbell D. R. , Wojciechowski B. W.
Published: March 2009

The catalyst decay theory of Wojciechowski(1) is applied to a simplified theoretical mechanism of catalytic gas oil cracking. The resulting patterns of selectivity are presented and general conclusions drawn. It is shown that selectivity in gas oil cracking is bounded by optimum and minimum performance envelopes which confine the range of possible product distributions.
Studies on cocurrent gas‐liquid flow in helically coiled tubes. I. Flow patterns, pressure drop and holdup
Authors: Banerjee Sanjoy , Rhodes Edward , Scott Donald S.
Published: March 2009

The effects of tube diameter, coil diameter, helix angle and liquid viscosity on flow patterns, pressure drop and holdup for cocurrent gas‐liquid flow in helically coiled tubes have been investigated. Nine coils of varying coil diameter and helix angle have been used with liquids of three different viscosities and air at varying pressures. The effect of tube diameter on pressure drop and holdup was determined by using tubes of diameters up to 2‐in.

Flow patterns were adequately predicted for all the systems by Baker's plot. Small helix angles were found to have no effect on pressure drop or holdup in coiled tubes. Both pressure drop and holdup could be adequately correlated using the Lockhart‐Martinelli approach with modified correlating parameters.
Free convection boundary‐layer flow over horizontal plates and discs
Authors: Rotem Zeëv , Claassen Lutz
Published: March 2009

Free convection flows near horizontal surfaces are discussed for those cases in which a similarity solution can be obtained. Particular cases considered are those of asymptotically large and vanishingly small Prandtl numbers. The solution for the relevant velocity, temperature and pressure functions has to be carried‐out numerically. For the particular cases when the Prandtl number is either sufficiently large, or sufficiently small, this integration would yield general functions, no longer dependent on the Prandtl number. Numerical data are included.
Liquid‐liquid‐vapor equilibria in the nitrogen‐methane‐ethane system
Authors: Yu Paul , Elshayal I. M. , Lu Benjamin C.‐Y.
Published: March 2009

Liquid‐liquid‐vapor equilibrium compositions were measured for the nitrogen‐ethane binary and the nitrogen‐methane‐ethane ternary systems from –255° to –219.8°F and at pressures up to 591 psia. A forced‐recirculation apparatus was employed for the determinations. Experimental results were interpreted and correlated. Optimum operating temperature for nitrogen separation has been suggested.
The kinetics and mechanism of the hydration of magnesium oxide in a batch reactor
Authors: Smithson G. L. , Bakhshi N. N.
Published: March 2009

The kinetics of the reaction between water and MgO powders has been investigated at 9°, 18°, 28° and 38°C in a stirred batch reactor. Six commercial samples of MgO prepared from Mg(OH)2 plus two of unknown origin, with specific surface areas of 12 to 80 mg/g, were studied. After correcting for particle size distribution, the rate of reaction was found to be directly proportional to the surface area contained in a shell at the surface of the particles. The activation energy is 14.1 ± 0.2 kcal/g‐mole indicating chemical reaction as the rate controlling process. A reaction mechanism has been proposed./
Granulation of superphosphate in a rotary drum
Authors: Linskson P. B.
Published: March 2009

Using water as a binding agent, some of the factors affecting the preparation of superphosphate granules have been investigated. The amount of water added to the material completely dominates the other physical variables in determining the characteristics of the granules formed. An optimum water content was found for which the proportion of granules within a specified size range (–4 + 14 Tyler mesh) was at a maximum.

Granulation with simultaneous drying showed that an increase in the drying rate results in a decrease in the rate of granule growth. The speed at which the granulator is rotated to obtain the correct “tumbling action” is influenced by the internal surface of the drum and the presence and design of internal flights.

The mechanical strength of superphosphate granules depends on the quantity of binding agent used in the granulation process and the degree of agitation. The dry strength of the granules formed is considerably greater than the wet strength.
Design of settling basins with allowance for residence time distributions
Authors: Silveston P. L.
Published: March 2009

Equations are developed for the performance of settling basins where hydraulics are characterized by residence time distributions. An illustrative calculation for a typical basin design using literature settling data and a residence time distribution predicts a reduction in solids removed of only about 10% over that predicted for an ideal basin where plug flow is assumed. This calculation suggests that the effect of residence time distribution on basin performance for realistic conditions may be just modest.
Drag reduction in large tubes and the behavior of annular films of drag reducing fluids
Authors: Seyer F. A. , Metzner A. B.
Published: March 2009

Turbulent flow drag reduction is governed by elastic effects within the boundary layer of the flow. The effect of elasticity is to reduce the radial momentum transfer rates of large eddies that exist near the tube wall, and in so doing a reduction in the turbulent flow drag occurs. A recent theoretical analysis is used to formulate a general discussion of the significant features of drag reducing systems and is used to predict quantitatively the percentage reductions in drag for systems of practical significance. It is shown that little or no drag reduction can be expected in large tubes using polymeric materials that are presently available though micellar systems show effects of substantial magnitude which appear to be exploitable.

An analysis is presented which indicates that laminar annular films of dilute polymeric fluids, used to enable the core fluid or a capsule to “slide” through a pipeline at reduced pressure drop, are of especial interest in that the normal stress field may generate forces which increase the concentricity of the core in the presence of major density differences. This exploitation of non‐Newtonian fluid properties, suggested some years ago by Lummus, does not appear to have been subjected to analysis before, nor do verifying experimental data appear to be available.
A lumped parameter approximation to a general model for catalytic reactors
Authors: McGreavy C. , Cresswell D. L.
Published: March 2009

Consideration ig given to the solution of the highly exothermic fixed bed catalytic reactor problem taking into account heat and mass transfer resistances inside the catalyst pellets and across the external fluid film, as well as radial temperature and concentration gradients in the fluid phase. Even on large digital computers, the computation time is excessively long if the sets of differential equations are solved simultaneously. By considering the intra‐particle equations in detail, it is shown that they may be reduced to a lumped parameter form which permits rapid evaluation of an effectiveness factor. The functional dependence of this effectiveness factor is determined primarily by the external film resistance. While still retaining the characteristics of the general problem, the lumped parameter approximation may be solved in a substantially shorter time, thus permitting its use in optimization and control studies.
Prediction of flow patterns in horizontal two‐phase pipe flow
Authors: Al‐Sheikh J. N. , Saunders D. E. , Brodkey Robert S.
Published: March 2009

A new concept of a sequence of plots is used for the separation of flow regimes in two‐phase flow. The empirical correlations themselves are based on extensive tabulations of flow‐type data from the AGA‐API Data Bank. Provided these data and the tabulations are accurate, the accuracy of the proposed method is better than 5%. The accuracy for any separation can easily be obtained from the information given.

The probability of being able to separate flow types by the various correlations was determined and used to select the best correlations. In actual use, there will be times when a complete separation cannot be made. However, one will know this and be able to say that the flow is one of two or, rarely, more types.
The viscosity of fluidized beds
Authors: Grace J. R.
Published: March 2009

The apparent shear viscosities of a number of fluidized systems have been estimated using an empirical approach based on the shape of spherical‐cap bubbles rising in real liquids. Values range between 4 and 13 poise, and agreement with direct experimental results is very good.
Effect of dilute polymer solution injection on external boundary layer phenomena
Authors: Latto B. , Shen Chi Hung
Published: March 2009

This paper describes an experimental study of the effect of injecting dilute aqueous polymer solutions into a turbulent boundary formed on a flat plate. Using hot film anemometry, it was found that the momentum diffusivity was less than that for pure water, and that there was a reduction in the size range of the turbulent eddies. Furthermore, it was observed that the angle and velocity of injection of a polymer solution can have a pronounced effect on the local skin friction, which under certain conditions could be reduced by as much as 80% when compared to no injection conditions.
Mass transfer produced by laminar flow oscillations
Authors: Rice Richard G. , Eagleton L. C.
Published: March 2009

Mass transfer produced by laminar flow oscillations was studied theoretically and experimentally. A hollow tube was caused to oscillate between two constant volume reservoirs with a constant concentration difference. Experimental axial mass transfer rates of hydrochloric acid in water were found to be from 20 to 1100 tmies that of ordinary diffusion for a Reynolds number range of 0.07 to 0.84. The coupled momentum‐mass transfer equations were solved and show excellent agreement with the experimental work. The average deviation from theory for all experiments was 6.44%. The theoretical results show that the mass transfer increase is proportional to the square of amplitude and depends, in a complex way, on the Reynolds and Schmidt numbers.
The dynamics of extraction processes: Part III. The determination of steady state and transient concentration profiles
Authors: Pollock G. G. , Johnson A. I.
Published: March 2009

Techniques for determining concentration profiles during the transient and final steady state operation of a countercurrent extraction column are described and evaluated. The column is mechanically agitated and the stages are separated using Teflon sieve trays. The paper discusses numerical procedures for analyzing the behaviour of such columns, and the errors introduced by the measurement techniques studied. Mass transfer coefficients for the column under study are reported, and there is a discussion of the effect of concentration (or position along the column) on their value.
The dispersion of solute in turbulent pipe flow of non‐newtonian fluids
Authors: Wasan D. T. , Dayan J.
Published: March 2009

The dispersion of solute in turbulent pipe flow of power law fluids is investigated theoretically. Results in terms of the intensity of dispersion are compared for the non‐Newtonian and purely viscous Newtonian fluids over a wide range of Schmidt numbers. The computed results indicate that the intensity of dispersion at a constant Schmidt and Reynolds number increases with increasing flow behavior index.
Kinetics and reactors — The engineer's dilemma
Authors: Smith J. M.
Published: March 2009

Scaleup of catalytic reactors is often unrewarding because of the incompatibility of chemical and physical similarity requirements. Hence, a rational design procedure usually requires experimental study of global rates of reaction, as well as kinetics of the chemical steps at a catalyst site.

This paper examines the role of laboratory and pilot‐plant reactor data in the design procedure. Recent developments in laboratory reactors, and the potential for ultimately eliminating the need for global rate measurements, are considered.
Evaluation of the three phase transport reactor
Authors: Pruden B. B. , Weber M. E.
Published: March 2009

A high aspect ratio chemical reactor for reacting a liquid with a gas in the presence of a finely divided catalyst was tested. The gas was sparged into the bottom of a tubular reactor with the slurry of liquid and catalyst flowing countercurrent to the gas. The liquid phase hydrogenation of alpha‐methylstyrene to cumene on a Pd. catalyst was studied in semibatch operation of the reactor with slurry recycle. The reacor was 1 1/2‐in. I.D. by 6‐ft. long. The following variables were studied at a temperature of 28°C and a pressure of 1 atm: superficial gas velocities of 1.1 to 3.3 cm/sec., and catalyst loadings from 0.4 to 2.0 gm. catalyst per liter. A model of the reactor was developed and successfully compared with the data.
Statistical methods in model discrimination
Authors: Reilly P. M.
Published: March 2009

Particularly in the chemical kinetic field but also in others in chemistry and engineering there has been much recent attention on the use of statistics in discriminating between rival models. There are two related basic problems. The first is to design experiments which will be most informative in determining which of several possible mathematical models is the “correct” one. Simple illustrations are given of the solution of this problem by different methods, such as the criteria of Roth, Box and Hill and of others, including some work done by R. S. Hawkins and the author on expected entropy change. The second problem is to analyze the data when received. A sampling of likelihood and Bayesian approaches to this problem is described with examples.
Mathematical models for the transient behavior of a packed bed Reactor
Authors: Feick J. , Quon D.
Published: March 2009

A mathematical model of a packed bed reactor was developed to include radial and axial diffusion within the reactor as well as film and pore resistances to both heat and mass flows. The non‐linear partial differential equations which are coupled by a generalized reaction rate expression were finite‐differenced and integrated in the time domain. The performance of the detailed model was compared with those predicted for two simpler models: a homogeneous reactor model and a surface resistance reactor model. The range of variables over which these considerations are important is also indicated.
Mass transfer within oscillating liquid droplets
Authors: Brunson Roy J. , Wellek Robert M.
Published: March 2009

All existing relations describing mass transfer within oscillating droplets were critically compared with experimental data in which resistance to transfer is predominantly inside the droplet. Several new relations are also developed to estimate oscillating droplet extraction efficiencies, one of which is recommended in view of its theoretical appeal, accuracy, and ease of application.

The most accurate relation currently available is an empirical expression developed by Skelland and Wellek.
The influence of mixing on the distribution of copolymerization compositions
Authors: Mecklenburgh J. C.
Published: March 2009

The paper shows theoretically that the composition distribution in a copolymer depends on both the type of continuous reactor used in its production and the molecular and macroscopic mixing patterns within the reactor. Examples are given of the distributions to be expected from a plug flow reactor, a CSTR with either molecular or macroscopic scale mixing, a tubular reactor with backmixing and reactors with several regimes of mixing. The distribution curves are compared with those obtained by tracer injection. A short account is given of the experimental difficulties encountered in reproducing the composition distributions.
Interaction model for the critical pressures of aliphatic hydrocarbon mixtures
Authors: Akiyama Tetsuo , Thodos George
Published: March 2009

An interaction model is proposed for the prediction of the critical pressures of multicomponent aliphatic hydrocarbon mixtures which may include methane. This model utilizeg a series consisting of terms of increasing order which has been truncated beyond the fifth interaction term. After a number of algebraic manipulations, the excess critical pressure for these multicomponent mixtures has been represented as follows

The nonmethane interaction coefficients Aij, Bij, Cij and βijk and the methane interaction coefficients A1j, B1j, C1j, D1j and β1jk have been expressed as functions of the critical pressure parameter, πij. The resulting relationships permit the evaluation of these interaction coefficients for a multicomponent system and from its composition, the critical pressure of the mixture is calculated. The critical pressures of several binary and multicomponent aliphatic hydrocarbon mixtures have been calculated and have been compared with experimental values. For 99 binary methane‐free mixtures representing 11 systems, the average deviation is 3.23%. For 46 binary mixtures representing six methane systems, the average deviation becomes 4.41 %. For 36 multicomponent aliphatic hydrocarbon mixtures containing from three to six components, the average deviation is found to be 3.18%.
Bed expansion and bubble wakes in three‐phase fluidization
Authors: Rigby G. R. , Capes C. E.
Published: March 2009

The expansion characteristics of gas‐liquid fluidized beds have been measured for beds of glass ballotini and sand with particle sizes ranging from 120 to 775 microns. This data has been used in conjunction with recent measurements of bubble properties to predict the proportion of wake associated with bubbles rising through the bed using a modification of the theory proposed by Ostergaard to explain the contraction observed when gas is introduced into a liquid fluidized bed.

Three‐pase fluidization has also been observed by photography in a two‐dimensional bed and the results are in substantial agreement with the calculations based on expansion behavior and bubble properties. The bubble wakes in a three phase system consist not only of a stable portion carried with the bubbles but also of vortices shed by the bubbles. A simplified model has been used to demonstrate that these vortices may contribute significantly to the observed contraction.
Local heat transfer coefficients in a model “falling film” scraped surface exchanger
Authors: Azoory S. , Bott T. R.
Published: March 2009

Utilization of an accurate technique to measure the local heat transfer coefficient in thin falling film scraped surface exchangers yields results which indicate that the local heat transfer coefficient is dependent on N0.5 and, above a certain rotational speed, independent of axial flow rate. Both of these observations are in agreement with the theoretical penetration model. The results, however, are generally lower than would be expected from the theory, and as a result, heat transfer may be described by the penetration model in combination with an empirical factor, f. This term is based on the liquid physical properties and gives a measure of the intensity of cross sectional mixing within the liquid, i.e.

where f, is defined as
A comparison of the performance of techniques for direct, on‐line optimization
Authors: Edler J. , Nikiforuk P. N. , Tinker E. B.
Published: March 2009

The performance of a number of well known optimization techniques has been compared with that of recently developed weighted‐mean random techniques, in the context of on‐line process control applications. It was found that one variation of the random technique compared favorably with the well known pattern search technique of Hooke and Jeeves in finding the maximum on simulated process response functions.

The study was performed by representing the processes by mathematical expressions. The effects of multidimen‐sionality, irregular response surfaces, scaling errors, and process noise were simulated in the tests that were performed for the comparisons.
Ternary systems: A numerical method for calculation of vapor‐liquid equilibrium data from total pressure measurements
Authors: Ramalho R. S. , Bui V. T.
Published: March 2009

A numerical method for calculation of vapor‐liquid equilibrium data for ternary systems, from total pressure measurements, is developed. The proposed method is applied to the ternary systems benzene‐n heptane‐n propanol and acetone‐methanol‐water.
Annular flow of two immiscible liquids I. Mechanisms
Authors: Hasson D. , Mann V. , Nir A.
Published: March 2009

A study was made of the flow mechanisms of two immiscible liquids with a small density difference introduced at a horizontal‐pipe inlet in initial concentric flow. Extent of the annular flow, its break‐up mechanisms and the subsequent flow patterns encountered were investigated with the aid of high‐speed photography.

Annular‐flow break‐up was found to occur by one of two mechanisms: collapse of the core‐liquid by varicose Rayleigh‐type waves or rupture of the top‐wall liquid‐film, attenuated by the ascent of the lighter core‐liquid. Flow patterns observed after break‐up involve fine dispersions, slugs or stratified layers. Charts mapping flow‐pattern zones show conditions under which annular‐flow holds over a considerable extent.
Studies on cocurrent gas‐liquid flow in helically coiled tubes. II. Theory and experiments on turbulent mass transfer with and without chemical reaction
Authors: Banerjee Sanjoy , Scott Donald S. , Rhodes Edward
Published: March 2009

Pure carbon dioxide was absorbed into distilled water and sodium hydroxide solution, in cocurrent two phase annular flow in helically coiled tubes in order to measure physical and chemical mass transfer coefficients and interfacial areas. (k*La) was correlated by the pressure drop in the test sections and interfacial areas were found to vary with the liquid phase energy dissipation.

According to a new theory, (k*L) has been shown to be a function of the root mean square vorticity near the interface. The root mean square vorticity has been related to the pressure drop, gas density, liquid flow rate and liquid velocity. The physical mass transfer coefficients theoretically predicted are in good agreement with experimental results.
Modeling and stability of catalytic fixed bed reactors
Authors: Hlavacek Vladimir
Published: March 2009

The existence of a multiple or oscillatory condition in a packed bed reactor, with a strongly exothermic reaction, is reviewed. The following cases are discussed: simultaneous heat and mass transfer within and outside a catalyst particle, axial mixing in tubular reactors and a recycle reactor. It is shown that the condition describing multiplicity can be estimated solely on the basis of the CSTR analysis. A correspondence between stability and parametric sensitivity is presented.