bluuebunny/crossref_metadata_2025 huggingface dataset:
The unsteady state absorption of oxygen in cumene
Authors: Low David I. R.
Published: March 2009

New data are reported for the absorption of single bubbles of oxygen less than 5 mm in diameter in cumene at room temperature. Measured rates are compared with the theoretically predicted rates, based on new values of the diffusivity and solubility of oxygen in cumene, for absorption from spheres in potential flow and from rigid spheres. In the presence of the peroxide, which is a reaction product, absorption rates are high initially but decay after 15 seconds or so to a value expected for rigid spheres. The results are explained in terms of the accumulation of surfactant at the bubble surface.

Preliminary measurements of the dissolution of carbon dioxide bubbles in water in the same apparatus gave results similar to other determinations reported in the literature.
Pumping capacities in stirred tanks theory and application
Authors: Cooper R. G. , Wolf D.
Published: March 2009

The pumping capacities for the propeller and turbine type impellers were derived analytically. The velocity and angle profiles along the blade width of a turbine impeller were also obtained.

The applications of the pumping capacities in the simulation of a stirred tank reactor, in the derivation of the power consumption and intensity of segregation, and in the correlation of the heat transfer in a stirred tank, have beer given.
Computational methods in process optimisation: II. Variable recycle ratio or reactor length with bounded control
Authors: Paynter J. D. , Bankoff S. G.
Published: March 2009

The work of Part I on the optimal design of a tubular reactor, in which a second‐order reversible exothermic reaction is being conducted, with recycle of unconverted reactant, is here extended to the cases where either the residence time (reactor length) or the recycle ratio is not specified in advance. Bounds are imposed on the control variable, which is here the local heat transfer conductance from the cooling jacket to the reactor. A gradient technique in control space, accompanied by a search for the optimal switch points, was again effective. With this combined technique singular control arcs were located by the appearance of rapid oscillations of the switching variable.
Air flow in a tube with a diverging inlet: I. Development of the turbulent velocity profile
Authors: Lana I. G. Dalla , Christiansen S. E.
Published: March 2009

The results from an experimental study of the development of air velocity profiles in a vertical 6.25‐in. I. D., 28.5‐ft. long aluminum tube with a diverging conical entrance are reported. Using the axial development of centerline velocity as a starting‐length criterion, a maximum and asymptotic value was approached at 40 diameters from the tube entrance. The starting length was found to increase with increasing Reynolds number. The large center‐line velocity associated with the jetting of air from a 1‐in. I. D. tube into the diverging conical entrance enabled a more rapid development of the velocity profile than for the well known case of a converging rounded entrance. A limited comparison of undeveloped and fully developed velocity profiles in the turbulent core region of the 6.25‐in. tube was also made over Reynolds numbers from 9,000 to 55,000.
Kinetics of catalytic oxidation of methane: Application of initial rate technique for mechanism determination
Authors: Ahuja O. P. , Mathur G. P.
Published: March 2009

A kinetic investigation on the oxidation of methane using a palladium catalyst was conducted. Conversions of methane were small and limited to about 10% to facilitate the use of initial rate approach. Plots of initial rate against total pressure and varying feed composition were used to interpret the data qualitatively. Regression coefficients from linearized rate equations and criteria of best fit were used to arrive at a plausible mechanism. The experimental results indicated that the reaction rate is controlled by surface reaction in which the adsorbed oxygen and adsorbed methane react to produce adsorbed carbon dioxide and adsorbed water.
Prediction of multicomponent diffusion coefficients
Authors: Cullinan Harry T.
Published: March 2009

A predictive theory based on the modified absolute rate theory is extended to the prediction of diffusion coefficients in the concentrated regions of multicomponent liquid systems without the use of adjustable parameters. A scheme for the direct prediction of multicomponent diffusion coefficients in non‐associated liquid systems is presented, analysed and tested with available data.
Laminar flow in regular polygonal shaped ducts with circular centered cores
Authors: Ratkowsky D. A. , Epstein Norman
Published: March 2009

The method of least‐squares fitting of harmonic functions to known boundary conditions has been employed to obtain closed‐form solutions for laminar flow of an incompressible fluid through the constant area annulus between a regular polygonal duct and a centered circular core. The product of Fanning friction factor and Reynolds number has been determined for the entire range between the extreme case of no core and the other extreme case where the core touches the outerwalls. For the latter case, it is shown that when the number of sides of the polygon approaches infinity, f.Re approaches a minimum value of 6.22. The analysis of this case is further extended to corner angles less than 60°, the minimum imposed by an equilateral triangular duct.
The Simulation of Single Phase Tubular Reactors with Incomplete Reactant Mixing
Authors: Harris I. J. , Srivastava R. D.
Published: March 2009

The influence of reactant segregation and of the rate of reactant mixing on fast homogeneous chemical reaction rates is considered and a computer model presented to simulate the effect of mixing within a tubular reactor fed by two segregated but miscible streams.

Results obtained from use of the model are discussed.
The effect of particle size distribution on packing density
Authors: Sohn H. Y. , Moreland C.
Published: March 2009

The packing density of a multi‐particle system is found to increase if the particle size distribution is extended. Results are reported for Gaussian and log‐normal size distributions using dense random packing of two sands with particle sizes of front <0.07 to 8.0 mm.

Packing density is shown to be a function only of size distribution represented by a dimensionless standard deviation, and of particle shape. It is independent of particle size.

Packing densities of binary mixtures of continuously distributed systems are found to depend upon the composition of the mixture, the mean‐size ratio of the components of the binary, and upon the packing density of the individual components. Maxima occur at compositions of 55 to 75% larger component, and increasing mean‐size ratios result in greater packing densities.

The “increase in packing density” factor is a useful function for comparing, and setting limits to, packing densities of binary mixtures.

The results should allow improved prediction and control of packing densities of many commonly encountered particle systems.
An extension of the principle of congruence applied to the evaluation of heats of solution for binary systems
Authors: Ramalho R. S. , Rvel Maurice
Published: March 2009

A modified principle of congruence is applied to the prediction of heats of mixing of binary systems. The principle is here applied to n‐alkanes binary mixtures and its application to other binary mixtures is also examined.
Velocity, subcooling and surface effects in the departure from nucleate boiling of organic binaries
Authors: Andrews D. G. , Hooper F. C. , Butt P.
Published: March 2009

The forced‐convection loop at the University of Toronto was used to determine DNB heat fluxes for the full range of variation in composition of the binary systems acetone‐toluene and benzene‐toluene, over the velocity range 1.09‐4.36 metre/sec. and the subcooling range 10‐50°C. Special attention was given to the precise location of the DNB point relative to the maximum (critical) heat flux.

The variation of the DNB heat flux with composition was found to be complex, but an empirical graphical correlation was obtained for each system, correlating DNB heal flux with composition, velocity and subcooling.

A limited study of the effect of degree of surface roughness pointed towards an effect on DNB which varied with the degree of subcooling, but which was independent of the coolant velocity.
Multi/level optimisation applied to a catalytic cracking plant
Authors: Brosilow C. , Nunez E.
Published: March 2009

New insight into Lasdon's multi‐level optimization technique is provided by new theoretical developments and the first application of the technique to a real industrial process. These results clearly display many of the merits and demerits of this new method of optimization.
Liquid hold‐up and minimum fluidization velocity in a turbulent contactor
Authors: Chen B. H. , Douglas W. J. M.
Published: March 2009

Transient‐response experiments have been performed in conjunction with bed expansion measurements to determine liquid hold‐ups and minimum fluidization velocities in a 12‐in. turbulent‐bed gas‐liquid contactor. The amount of liquid hold‐up was found to be independent of gas velocity, but dependent upon both liquid rate and packing diameter in the same manner as reported for conventional fixed‐bed absorbers. The data on minimum fluidization velocity, Gmf, which was interpreted in the present study as the maximum gas mass velocity at which the bed maintained its static height, showed a considerable variation with packing diameter, dp and liquid flow rate, L. A correlation of Gmf with dp and L was presented.
Problems in modelling and the study of electrochemical reactor dynamics
Authors: Babajide A. B. , Fahidy T. Z.
Published: March 2009

Proper understanding of the unsteady state behavior (start‐up, shut‐down, process perturbation effects, etc. …) of electro‐chemical reactors requires realistic mathematical modelling. Inexact current knowledge of all thermodynamic, hydrodynamic and kinetic aspects of electrochemical systems, in addition to inherent mathematical complexities requires approximations to allow the characterization of such systems via control engineering principles. The usefulness of the process dynamics approach is illustrated by practical examples.
Calculating complex chemical equilibria by an improved reaction‐adjustment method
Authors: Smith W. R. , Missen R. W.
Published: March 2009

Improvements in calculating complex chemical equilibria have been obtained (1) by incorporating a convergence‐forcer into the Cruise‐Villars method (a reaction‐adjustment method), and (2) by using a linear programming scheme to obtain an initial estimate of the equilibrium composition. Calculations on 50 problems show that the improved method is faster than the RAND method similarly modified (one that does not use stoichiometric equations).
Densities of hydrocarbons in their saturated vapor and liquid states
Authors: Bradford Michael L. , Thodos George
Published: March 2009

The Sum and differences of the saturated vapor and liquid densities of 23 hydrocarbons were used to develop the following reduced density relationships for these saturated states

The hydrocarbons considered included n‐parafins, olefins, diolefins, naphthenes, and aromatics. Constants β, γ, and δ, and exponentnwere found to be dependent on,. Equation (a) can reproduce liquid densities with an overall average deviation of 1.1 % over the entire temperature range, while Equation (b) was found to apply only in the interval 0.900 ≤TR≤ 1.00 with an average deviation of 2.2%.

For temperatures ofTk< 0.90, the saturated vapor density was found to depend on temperature as follows

wherekandmwere also found to beZcdependent. Values calculated using Equation (c), when compared with 81 available experimental densities for 12 hydrocarbons, produced an average deviation of 3.0%.
Chlorine exchange resins
Authors: Wayman M. , Salamat H. , Dewar E. J.
Published: March 2009

The authors have prepared high polymers which contain a labile chlorine atom. The active group in these polymers is the >NH or —NH2 group, which takes up chlorine from a chlorine‐rich environment, and in the chlorinated form gives up chlorine to an environment deficient in chlorine, for example which exhibits a chlorine demand. The resins, which may be natural or synthetic, act as an agent for chlorine transfer to or from a medium. The results of a preliminary investigation of the utility of various polyamides and amino resins are given. Mass transfer rate studies of chlorine uptake by a urea‐melamine‐formaldehyde resin and of chlorine liberation from a chlorinated resin of the same type, the effect of pH on these rates, and the practical maximum chlorine capacities are presented. The stability of chlorinated resins is described.
The effect of surface active agents on sorption isotherms of a model food system
Authors: Labuza Theodore P. , Rvtman Max
Published: March 2009

The extent of the capillary condensation phenomenon in the sorption of water by a model food system was studied. The system, composed of microcrystalline cellulose, a hydrocarbon oil, and water, was treated with non‐ionic surface active agents at various concentrations. Desorption and adsorption isotherms were made for triplicate control and treated systems at 37°c., using a desiccator method.

During desorption, the surfactants increased the water equilibrium vapor pressure of the model system for all moisture contents, but with adsorption, this effect was observed only up to 50 to 60% RH. The magnitude of the hysteresis loop was diminished in all cases. These over‐all effects were due mainly to a lowering of the liquid surface tension of the water in the pores of the model. Capillarity was analyzed by the Kelvin Equation and existed down to 20% RH, which is close to the monolayer value for most models. In addition, data from low surfactant concentrations indicated that capillarity may extend even below the monolayer. The diminished hysteresis found in our experiments supports the “ink‐bottle” theory of hysteresis.
Geometric parameters for some flow channels
Authors: Tiu C. , Kozicki W. , Phung T. Q.
Published: March 2009

A method was proposed earlier(1) for prediction of the average velocity or pressure drop in the flow of non‐ Newtonian fluids in conduits of arbitrary cross section. The method requires only a knowledge of two geometric parameters which characterize the flow geometry, and the fluid model equation. In this paper, evaluations of geometric parameters are presented for infinite and finite (enclosed)square and triangular arrays of cylinders, and for regular polygonal and star‐shaped conduits. With these parameters, predictions of the average velocity or related variables for the Zlow of any arbitrary non‐Newtonian fluid can now be made. Comparisons are made with recent analytical solutions and experimental data pertaining to non‐Newtonian flow in concentric annuli, and equilateral and right isosceles triangular ducts, which give additional support to the reliability of the proposed method.
An improved correlation for film boiling heat transfer on horizontal tubes
Authors: Sarma P. K. , Ravisankar G. , Apparao K. Venkata
Published: March 2009

An analysis of the distinct wave pattern of the vapor layer formation around a cylindrical heater element during film boiling yields a method to correlate the heat transfer coefficients in terms of the break‐off diameter of the bubble, frequency of the bubble emission, wave length (spacing of the bubbles) and other physical properties of the fluid.
Etude cinétique de la déshydrtation du sulfate de cuivre par thermogravimétrie et thermogradientimétrie
Authors: Kaliaguine Serge
Published: March 2009

Une thernlobalance d'un type nouveau a été construite. Les déterminations de témperature sont faites par thermogradientimetrie. Un ereuset d'un type special permet de plus un contrhle précis de l'atmosphére au contact de 1′échnntillon. Des mesures cinétiques des trois déshydratations du sulfate de cuivre ont permis d'attribuer un ordre nu1 á ces trois réactions et de définir une énergie d'activation apparente isobare. Cette dernéhre grandeur a étć mesureée sous diverses pressions de vapeur d'eau.
Phase behavior of the methane‐carbon dioxide‐n‐butane and methane‐hydrogen sulphide‐n‐butane systems
Authors: Saxena A. C. , Robinson D. B.
Published: March 2009

Experimental vapor‐liquid equilibrium data have been obtained for the methane‐hydrogen sulphide‐n‐butane and the methane‐carbon dioxide‐n‐butane systems at temperatures of −20°, 40° and 100°F. and at 400, 800 and 1200 psia pressure for each temperature. The data for the latter system show disagreement with the work of previous authors on this system at some of the conditions studied. The data were obtained using a variable volume cell with mercury as the confining fluid. A new type of internal valve was designed to provide a better means of establishing equilibrium between the liquid and vapor phases.

The presence of hydrogen sulphide and carbon dioxide caused a two to three‐fold elevation in the hydrocarbon K‐values. Predictions of the vapor‐liquid equilibrium behavior for these systems utilizing the Chao‐Seader correlation and the Wilson equation were unsatisfactory. The K‐values for hydrogen sulphide and carbon dioxide obtained from the NGSMA Engineering Data Book differ up to 50% from the experimental K‐values.
The application of regression methods to the BWR equation for calculation of volumetric and thermodynamic properties
Authors: Eubank P. T. , Fort B. F.
Published: March 2009

This paper describes the methods used by the authors to revise the A.P.I. Project #44 selected thermodynamic properties tables for gaseous methane and gaseous ethane. For both gases, the experimental, literature, volumetric data were segregated into pressure — temperature or density — temperature regions. BWR coefficients were found for each region by various regression methods. A differential BWR equation is developed for the ethane project which guarantees continuity of the volumetric and thermodynamic surfaces at the interfaces between regions. Such data fitting techniques, which require the use of high‐capacity, highspeed, digital computers, are necessary for accurate representation of PVT data over wide ranges of pressure and temperature. Equations representing the volumetric properties of methane and ethane are presented and compared against the experimental data and the results of previous data representations.
The rate of selenium removal from tellurium by hydrogen purging
Authors: Rawling J. R. , Toguri J. M.
Published: March 2009

The reaction between hydrogen gas and selenium dissolved in liquid tellurium is described as follows

H2(g) + Se ⇄ H2Se(g)

The kinetics of this reaction have been investigated at temperatures ranging between 525 and 625°C and at concentrations of selenium varying between 250 and 3,300 ppm. Under all conditions investigated the reaction was controlled by transport processes in one or other of the two phases depending on the relative values of the mass transfer coefficients. Subject to the assumption that the solution of selenium in tellurium is an ideal one the molecular diffusion coefficient of mixtures of hydrogen selenide in hydrogen, Dg, is approximately 1.6 cm.2 sec.−1 at 525°C, and 2.1 cm.2 sec.−1 at 625°C. In view of complicating factors accurate values of the diffusivity of selenium in liquid tellurium cannot be deducted from the experimental results. However, the value obtained from experimental measurements of 7.59 × 10−4 cm.2 sec.−1 at 525° is in reasonable agreement with the value of 9.85 × 10−5 cm.2 sec.−1 reported in the literature.
Precise parameter estimation in reaction modelling — sensitivity in choosing experimental conditions
Authors: Mezaki Reiji
Published: March 2009

A sequential experimental design developed by Box and coworkers was reviewed and the sensitivity of experimental conditions in increasing the preciseness of parameter estimates was examined. Continuous kinetic data were utilized for the examination. It is found that experimental conditions are in some cases rather sinsitive and slightly deviated experimental conditions from those specified by the criterion may induce some difficulty in reducing the size of confidence region of parameter estimates.
Diffusional phenomena and apparent kinetics for nth‐order gas‐solid non‐catalytic reactions
Authors: Tartarelli R. , Morelli F. , Capovani M.
Published: March 2009

The influence of the diffusional phenomena on the apparent kinetics for nth‐order gas‐solid non‐catalytic reactions

is studied assuming the unreacted‐core model. Flat‐plate, cylindrical and spherical particles are considered, the size of which may vary with extent of reaction. Specific methods of contacting of fluid with solid are taken into account, but their influence on the results are not remarkable. At high conversions of cylindrical and spherical particles, the process is always chemical reaction controlled.
The vapor‐phase oxidation of benzene over a vanadium oxide catalyst
Authors: Jaswal I. S. , Mann R. F. , Juusola J. A. , Downie J.
Published: March 2009

The kinetics of the reaction of benzene with oxygen over a vanadium oxide/potassium sulphate‐promoted catalyst have been studied in a differential flow reactor. Rates of oxidation of benzene to maleic anhydride, p‐benzoquinone and carbon dioxide were measured at temperatures from 350 to 400°C, at benzene concentrations from 2.0 to 4.33 × 10–8 moles/1, and at oxygen concentrations from 1.6 to 15.0 × 10–3 moles/1.

The rate data were correlated by the steady state adsorption model and, by comparison with previous published results, it was concluded that this model provides a valuable means of correlating and interpreting catalytic oxidation rate data. Earlier data for benzene oxidation on the same catalyst were critically evaluated and a possible source of error was suggested.
Liquid phase relationships in fertilizer granulation by a layering process
Authors: Sherrington P. J.
Published: March 2009

In certain variants of the fertilizer granulation process granulation occurs by deposition of a layer of raw material onto a previously formed nucleus. An expression for the liquid phase required for layering as a function of the proportion of nuclei present has been derived from a simple model of the layered granule and tested against laboratory simulation experiments on glass beads and sand. The expression is applied to fertilizer granulation to define the range of conditions over which layering is possible and the recycle ratios required as a function of fertilizer solubility and the water entering the granulator. Layering requires a higher recycle ratio than the corresponding agglomeration process, but in general gives product with better storage properties and shorter drying time. The economics of the process depend on the saving in drying costs compared to the cost of extra conveying equipment. Modifications to the basic process to improve its economics are considered briefly.
Heat transfer between an axisymmetric jet and a plate held normal to the flow
Authors: Sitharamayya S. , Raju K. Subba
Published: March 2009

Heat transfer between a submerged jet of water and a flat surface held normal to the flow was studied experimentally over a wide range of plate to nozzle diameter ratios (8 ⩽ D/d < 58). The average heat transfer coefficients were found to be independent of nozzle to plate distance (γ) in the region studied, (γ/d < 7). An equation was developed by separating the target area into the impingement and the wall jet regions. The data were correlated by

For nozzle Reynolds numbers 2,000 to 40,000; D/d ⩾ 8 and γ/d < 7.
Heat transfer rates to newtonian fluids in aUSn anchor‐agitated kettle
Authors: Moo‐Young M. , Cross J. V.
Published: March 2009

Heat transfer rates to Newtonian fluids in a jacketed kettle using anchor agitators have been measured. Experimentally evaluated liquid‐film heat transfer coefficients at the vessel walls can be correlated by the modified Sieder‐Tate equation as used by previous workers but the results of the present and previous work are shown to be better correlated by the application of the theory of local isotropic turbulence. An attempt has also been made to establish the effect of wall clearance on the heat transfer efficiency of the contactor. The results indicate that high heat transfer rates obtainable with agitator‐scrapers can be realized with anchors without scrapers.
A survey of recent soviet research on the drying of solids
Authors: Fulford George D.
Published: March 2009

The importance of internal moisture migration in the drying of solids and the various approaches to the study of this phenomenon are outlined briefly. The extensive Soviet work in this field, particularly by Lykov's school, is reviewed, and the advantages, disadvantages and practical applications of this approach are discussed. Some of the more interesting practical Soviet studies of drying plant and processes are also mentioned briefly.
Experimental vapor‐liquid equilibria for hydrogen‐nitrogen‐methane‐ethane‐ethylene
Authors: Cohen A. E. , Hipkin H. G. , Koppany C. R.
Published: March 2009

Isothermal vapor‐liquid equilibrium data have been obtained for hydrogen‐methane‐ethane‐ethylene at –250°, –200°, –150°, –100% and –50°F, and for hydrogen‐nitrogen‐methane‐ethane‐ethylene at –150°F. Pressures were up to 2000 psia. Prediction methods of Lenoir, Chao‐Seader, the Data Book of the American Petroleum Institute, and the Data Book of the Natural Gas Processors Suppliers Association (NGPSA) are compared with the experimental data.
Residence time distribution in continuous flow stirred tank reactors
Authors: Hsiang T. C. , Reilly Park M.
Published: March 2009

Numerical values of the cumulative residence time distribution in a continuous flow stirred tank reactor are commonly required. It is shown in the paper that the above distribution is easily transformed into a Chi‐squared distribution. This provides a fast easy way of obtaining the desired values from readily available statistical tables.
Velocity distributions in a gaseous plasma: II. Application of a flow model to a helium plasma
Authors: Mevbvs P. , Parent J. R.
Published: March 2009

A mathematical model for gas velocity distributions and definition of flow types is applied to a helium plasma operated at 27 kW and a gas flow rate of 7.2 g/minute under pressures of 760 mm and 300 mm Hg.

The calculated velocity data are used to predict values of thermal conductivity and viscosity for helium in the plasma. A good approximation to theoretical values is obtained, lending validity to the model of velocity distributions.
Kinetics of the ammoxidation of propylene over a bismuth‐molybdate catalyst
Authors: Shelstad K. A. , Chong T. C.
Published: March 2009

Integral conversion data for the ammoxidation of propylene were obtained using a flow reactor and 10.0 gms. of a bismuth‐molybdate catalyst. Analysis by gas chromatography for carbon‐containing compounds in the product gases showed the presence of unreacted propylene, acrolein, acrylonitrile, carbon dioxide and small amounts of acetonitrile.

The data obtained at 390°C were correlated on the basis of a simplified scheme of first‐order reactions with acrolein as an intermediate. The results from experiments at higher temperatures and with reduced amounts of oxygen in the feed indicated that both the activity and selectivity of the catalyst were affected by the oxygen content of the catalyst.
Reduction of sodium sulphate with hydrogen in a fluidized bed reactor
Authors: Puttagunta Venugopala Rao , Decoursey W. J. , Bakhshi N. N.
Published: March 2009

Reduction of sodium sulphate to sulphide with hydrogen was studied in a batch fluidized bed reactor. The principal difficulty was fusion of the particles, as some melting was found to be present in the practical range of temperatures. Fusion and agglomeration were minimized by pre‐heating the gas, increasing particle size, and recycling some reduced material. Reaction rates were studied at 649 to 732°C., and an empirical rate equation was fitted to the data. Possible explanations of the rate equation are discussed: changes in reactive surface area, perhaps by a blocking mechanism, appear to be significant.
A flowsheet drawing program for a visual display computer
Authors: Forder G. J. , Hutchison H. P.
Published: March 2009

A program for a visual display computer is described which enables a user to ‘draw’ pictures closely resembling chemical plant flowsheets. It is thought that this approach could be useful as a means of introducing the problem structure into the computer and also as a visual aid for the user.

Specifications are described which were laid down for this new program and which were formulated as a result of experience gained with a previous more general network drawing program. An account is given of the major problems which arose in the implementation and the solutions which were adopted.
Calculation of binary vapor composition from solution vapor pressure
Authors: MacKay D. , Wong K. K.
Published: March 2009

A rigorous computational method is proposed for the calculation of binary vapour compositions from measurements of total vapour pressure of solutions of known composition and temperature. It is based on the repeated solution of an algebraic equation obtained by writing the Gibbs‐Duhem equation in terms of fugacity in finite difference form.
Hydrodynamic studies on two multistage mixer‐settlers
Authors: Hanson C. , Sharif M.
Published: March 2009

A knowledge of the hydrodynamic characteristics of mixer‐settlers is necessary for prediction of their performance under transient conditions. Residence time distribution studies are reported for the heavy phase in two types of mixer‐settler. These show the flow pattern to be intermediate between perfect mixing and perfect plug flow. A relationship is developed to describe the flow pattern and the various parameters are evaluated for the two units studied.
Axial dispersion with chemical reaction in packed bed reactors
Authors: Corrigan Thomas E. , Bauer Jerome L. , Dean Michael J.
Published: March 2009

Data on axial dispersion in packed beds is presented. The effect of axial dispersion on first and second order reactions in packed beds in the near plug flow region is predicted from transient response with no reaction.
A fluid‐diode contactor
Authors: Thompson D. W.
Published: March 2009

Some of the phenomena made use of in fluidic control devices may also be of utility in designing chemical contacting equipment. An intermittent‐flow countercurrent contactor is described which makes use of flow‐interference effects to convert an alternating applied pressure into countercurrent motion of the two phases. Some design principles of the contactor are discussed and experimental flow measurements reported. Mass‐transfer coefficients for the extraction of n‐butanol into water have been determined in a short test section and are compared to literature values for packed‐bed contactors. The contactor differs significantly from conventional devices in a number of ways, and may offer advantages in several applications: where emulsification is a problem, where simultaneous extraction and reaction are being carried out and heat must be transferred to or from the fluid, or where internal moving parts are undesirable because of corrosive conditions.
Laminar heat transfer in the thermal entrance region
Authors: Brunet J.
Published: March 2009

Series solutions for heat transfer in the thermal entrance region are presented for laminar flow in conduits (plane ducts, tubes, annular passages). The present solution of the equation of energy has been obtained for either a step change in heat flux or wall temperature and is valid for all time‐independent non‐Newtonian fluids, providing that the flow‐field is such that

vθ= 0,vr= 0,vg=vg(r)

From its general nature with regard to the flow‐field, such a solution is a convenient alternative to the eigenvalue solutions when applied in the thermal entrance region where a large number of eigenvalues and eigencoefficients are required.
A theoretical study of mass transfer with chemical reaction in drops
Authors: Watada H. , Hamielec A. E. , Johnson A. I.
Published: March 2009

A model has been developed for the preparation of mass transfer by forced convection inside drops for mass transfer with and without simultaneous first‐order chemical reaction.

Solutions of the forced convection equation have been obtained using finite difference methods for Reynolds number and viscosity ratio ranges of 0 ≤ Re ≤ 90 and 0 ≤ μ1/μo ≤ ∞, respectively. The effect of circulation rate inside the drop on the mass transfer rate has also been studied.

The model is believed to be generally applicable as evidenced by a comparison with existing analytical models. Thus the results for physical mass transfer approached the Kronig and Brink solution when the viscosity ratio tended towards zero in the Stokes' flow regime. However, as the viscosity ratio increased, the results approached the Newman solution. The model also agreed with those of Johns and Beckmann for physical mass transfer. Similarly, the results for mass transfer with first‐order chemical reaction agreed with Dankwerts' generalization of the Kronig and Brink and the Newman models.
Heat transfer to jackets with close clearance impellers in viscous materials
Authors: Coyle C. K. , Hirschland H. E. , Michel B. J. , Oldshue J. Y.
Published: March 2009

“Viscous mixing” as defined here includes the range of 5000 to 500,000 centipoises at 5 sec‐1 fluid shear rate. It was found that heat transfer coefficient with helical impellers were related to the clearance between the impeller and the tank wall and not influenced to any important degree by the speed or the fluid viscosity. The mechanism seems to be conduction through this stagnant film. “Convection‐type” correlations are not useful in describing the effect of operating variables.
On a reduced equation for gaseous diffusivity
Authors: Ramamurthy A. V. , Narsimhan G.
Published: March 2009

The application of the theorem of corresponding states to the HBS equation for binary diffusivity has resulted in the formulation of the following two generalized equations

T ≤ 1.875(TCA TCB)1/2

DAB (1 + α)2 ṁ Mr ṁ TCB3/13 ṁ PCA1/3/TCA1.07 = 3.65 × 10−4 ṁ TRA2/(ZCA)2/3 ṁ PRA

T ≥ 1.875 (TCA TCB)1/2

DAB (1 + α)2 ṁ Mr ṁ TCB1/12 ṁ PCA1/3/TCA0.92 = 6.45 × 10−4 ṁ TRA5/3/(ZCA)2/3 ṁ PRA

A critical diffusivity (Dc)AB has been defined based on the above equation

(Dc)AB = TCA(5/6 + n)/TCBn ṁ PCA1/3 ṁ Mr (1 + α)2

This equation has a form similar to one defined by Reid and Sherwood. After testing the two equations with diffusivity data for 25 systems, it is found that the average error of prediction is about ± 5.0%. The error of prediction with the second equation is only 3.0%.

The diffusivity equations have been shown to provide a satisfactory “reference substance” technique for estimation of binary diffusivity data.
Heat transfer with coiled wire turbulence promoters
Authors: Kumar P. , Judd R. L.
Published: March 2009

An experimental study of forced convection heat transfer and frictional power loss for water flowing in a vertical tube is reported in this paper. The study investigates the effect of coiled wire turbulence promoters of various pitch to diameter ratio (1.00–5.50) upon the Nusselt Prandtl modulus Nu/Pr1/3 and Fanning friction factor Cf for three different wire diameters, 0.052‐in., 0.063‐in. and 0.072‐in. Analysis of the computed results indicates that heat transfer increases by as much as 280%, though at the cost of much larger increase in frictional power loss. Consequently, coiled wire turbulence promoters can be used with advantage for cases where pumping power is not the dominating factor and reduction in weight and size of the equipment is more important.

The present results and those of three previous investigations of heat transfer in tubes with coiled wire turbulence promoters were satisfactorily correlated by the expression

which was found to be independent of the tube diameter, wire diameter, pitch to diameter ratio and the test fluid.
Effect of reynolds and prandtl number on the frequency response of concentric tube heat exchangers
Authors: Fisher D. G. , Kadlec R. H.
Published: March 2009

An analytical and experimental investigation was made of the frequency response of both the shell and tube fluid outlet temperatures of a six foot concentric tube exchanger to disturbances in either flow rate. The fluid Reynolds and Prandtl numbers were varied from 4,000 to 20,000 and 3 to 40 respectively.

The effect of increasing either the tube fluid Reynolds or Prandtl number, for both shell and tube flow disturbances, was to increase the attenuation and phase shift of the tube outlet temperature and decrease it for the shell outlet temperature.

The “resonance effect”, was observed experimentally.
Frequency response of different size concentric tube heat exchangers
Authors: Fisher D. G. , Kadlec R. H.
Published: March 2009

The frequency response of a concentric tube heat exchanger was investigated theoretically, and experimentally, on four different size heat exchangers. Transfer functions, for the response of both shell and tube fluid outlet temperatures to disturbances in either flow rate were derived. Experimental results for water‐glycol systems show that the mathematical model accurately predicts the frequency response of large heat exchangers operated at high Reynolds numbers. However, the attenuation and phase shift of the fluid outlet temperatures become significantly greater than predicted by the model when heat exchanger size is decreased or experimental conditions are changed to increase axial mixing.
Residence time distributions in jet stirred vessels with linear scale from 0.5 to 4 feet
Authors: Sinclair C. G. , McNaughton K. J.
Published: March 2009

This paper gives experimental details of the residence time distribution in cylindrical vessels with length to diameter ratios 1:1, 2:1 and 3:1, length from 0.5 to 4‐ft, and co‐linear axial inlet and outlet nozzles of 1/8 to 1‐in. diameter. The inlet jet was always turbulent with inlet Reynolds numbers in the range 3000 < Re < 10,000. A theoretical model is proposed which predicts the residence time distribution from vessel dimensions and fluid properties only without any empirical correlations. The experimental results show that the larger the scale of the reactor the more valid is the model.
Computer utilization in a kinetic study ofn‐butane isomerization
Authors: Carr Norman L. , Somers Allen E.
Published: March 2009

A three‐part technique was developed to study the kinetics of n‐butane isomerization. First, a graphical procedure was used to develop simple rate models for each set of experimental conditions. Second, the simple models were used in conjunction with reactor simulations to generate intrareactor rate and partial pressure data. Third, the pooled rate and partial pressure data were used to build comprehensive kinetics models. The isomerization kineticg were represented by dual‐site, surface‐reaction‐controlled models. The effects of temperature, pressure, hydrogen‐to‐hydrocarbon ratio, and space velocity on both isobutane yield and selectivity were determined.
Continuous flow mixing of two miscible liquids of different densities
Authors: Pelletier Martin , Cloutier Leonce
Published: March 2009

Positive step demands have been used to study the behavior of miscible liquids with different densities in an imperfectly mixed cylindrical flow tank. A model was elaborated to predict the response of the agitated system. Comparisons between experimental and theoretical results have shown the limits of the proposed model and equations.
Grid leakage in fluidized beds
Authors: Serviant G. A. , Bergougnou M. A. , Baker C. G. J. , Bulani W.
Published: March 2009

Solids leakage rates through different grids in two‐dimensional and cylindrical beds of cracking catalyst fluidized with air have been measured. Single and multihole perforated plate grids and single nozzle grids were studied. Leakage fluxes were related to the average air velocity through the grid holes. The effects of superficial gas velocity and grid loading were also investigated. The decisive advantage of using nozzles to mini‐ mize solids leakage in fluidized beds has been observed.
The development and evaluation of a theory of thixotropic behavior
Authors: Ritter R. A. , Govier G. W.
Published: March 2009

The consistency decay of a thixotropic fluid under sustained shear is similar in many respects to a first order — second order reversible chemical reaction and has been described in terms of an analogous kinetic model.

The data necessary for an experimental evaluation of the theoretical model were obtained through an analysis of the Theological behavior of Pembina Crude Oil. These data were then effectively correlated in terms of the theoretical expression.
A resolution with the congruence principle of viscosity in mixtures of n‐hexadecane and l‐n‐chloroalkanes at 25°C
Authors: Heric E. L. , Coursey B. M.
Published: March 2009

The viscosity of binary mixtures of n‐hexadecane with nine normal 1‐chloroalkanes from butyl through octadecyl at 25°C. is considered. This includes a range in kinematic viscosities from less than 0.5 to more than 8.5 centistokes. Resolution of departures from ideal flow, as defined with the Eyring viscosity equation, into homogeneous and heterogeneous aspects is described in terms of the restricted principle of congruence. Experimental viscosity values agree within about 1% with those calculated through the relationships obtained by the resolution. The method is also considered for the estimation of viscosities of mixtures of the present systems.
Gamma‐initiated iodination of methane in the gas phase
Authors: Vilenchich R. , Hodgins J. W.
Published: March 2009

Gamma radiation has been used to initiate the gas phase reaction between iodine and methane. Under appropriate conditions, the products are hydrogen iodide and the iodomethanes. The experiments were conducted over a range of temperature, concentration, and at two levels of total absorbed dose.

The existence of a chain reaction is presumed, on the basis of G‐values, which were as high as 7 × 107. In view of the propensity of iodine as a radical scavenger, this high efficiency might seem surprising, but may be attributable to the known autocatalyic effect of iodine in substitution reactions.
The oxidation of aqueous ferrous sulphate by thiobacillus ferrooxidans
Authors: MacDonald D. G. , Clark R. H.
Published: March 2009

The iron oxidizing bacteria, Thiobacillus ferrooxidans, were grown in an aqueous ferrous sulphate solution in batch and continuous culture vessels and the dependency of the specific growth rate on ferrous sulphate concentration, temperature, and pH are shown. The effect of carbon dioxide concentration on cell growth is also considered.

The phenomenon of wall‐growth is shown to be an important characteristic of the organism which must be considered in any batch or continuous culture experiments. The role that it may have in the biological leaching process is also indicated.
Prediction of heats of mixing by a group solution model with application to alkane/alcohol mixtures
Authors: Nguyen T. H. , Ratcliff G. A.
Published: March 2009

Group solution models of liquid mixtures have been used previously to predict excess free energies of non‐ideal systems. With increasing experimental data available on heats of mixing, the application of a similar model to excess enthalpies has been investigated. The model allows for both structural and group contributions to excess enthalpies. The former contribution is determined from experimental data on mixtures of alkanes. The group contribution has been determined at 25°C and 45°C for systems containing alkanes and alcohols. Predictions require no experimental data on the system in question, and are in good agreement with experiment. Limited extrapolation to other temperatures and group compositions should be satisfactory.
Single bubble formation at orifices submerged in viscous liquids
Authors: Swope Richard D.
Published: March 2009

This paper concerns the slow formation of gas bubbles at circular orifices submerged in liquids with viscosities ranging from 10 to 1000 poise. A mathematical model is developed for predicting the bubble lift‐off size as a function of, basically, Froude, Weber and Reynolds numbers; it is analytical and does not depend on semi‐empirical coefficients.

To check the validity of this model, experiments involving various gas flow rates and orifice diameters were performed in several liquids. The model consistently underestimates the experimentally obtained bubble size; the error of estimate varies from 10 to 25%. For bubble formation in a regime between the constant flow and constant pressure regimes, both the chamber pressure and the flow rate into the bubble vary. Furthermore, the instantaneous gas flow rate into the bubble can be many times greater than the average flow rate in the piping far upstream of the orifice exit. The former flow rate is important in determining the forces acting on the bubble and a method is given for obtaining its average value.
An experimental investigation of primary and secondary velocity for turbulent flow in eccentric annuli
Authors: Tebo Paul V. , Clump Curtis W.
Published: March 2009

Velocity profiles for the turbulent flow of air in annuli of high eccentricities were determined. Unusual isovel curvature suggestive of secondary flow was found, but hot‐wire measurements did not detect secondary flow within experimental accuracy. Evidence suggests that most of the observed isovel structure is due to developing flow and the remainder is a normal pattern of primary velocity. The use of irrelevant velocity correlations and not the assumption of negligible secondary flow is suggested as the reason for lack of agreement between recent flow hypotheses and measured velocities.
Non‐ideal flow parameters for viscous fluids flowing through stirred tanks
Authors: Moo‐Young M. , Chan K. W.
Published: March 2009

Residence time distribution functions for the flow of viscous fluids (6‐100 poises) through mechanically stirred tanks have been evaluated experimentally for various flowrates and stirrer speeds in three tank sizes, in geometrically similar systems. The results have been examined in terms of a mixed model suggested by visual observations of flow patterns within the tanks. A mechanistic model consisting of a dual backmix region and deadspace in series with a plug‐flow region was found to be compatible with these results. It was also found that previously tested models for stirred‐tank systems can be represented by limiting cases of this more general model. Further, it is shown that the parameters of the model can be expressed in useful engineering correlations derivable from the operating variables. Preliminary results on the effects of non‐Newtonian flow on the validity of the model are also presented. Application of the model to chemical reactor design is illustrated for first‐order reaction kinetics.
Axial dispersion in a tubular flow vessel with bends
Authors: Park Chan Mo , Gomezplata Albert
Published: March 2009

A two measurement points pulse techniqque was employed to determine axial dispersion coefficients in a 3/4 inch diameter pipe with four 90 degree bends located at 50 inch intervals. Water velocities corresponding to Reynold numbers of 3,800 to 11,500 were used. It was found that the effect of bends on the overall dispersion coefficient depends on the Reynolds number and a characteristic length.

Two mathematical models of a reactor with bends are presented. One model assumed that the bend section is a perfectly mixed reactor with an equivalent length. The second assumed a fixed equivalent length for the bend section and a proportional relationship between the dispersion coefficients in the bend and the straight section.