bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat transfer characteristics of boiling nitrogen and neon in narrow annuli
Authors: Lapin Abraham , Totten H. C. , Wenzel L. A.
Published: June 2004

The boiling characteristics of liquid neon and nitrogen in vertical annuli ranging between 0.006 and 0.080 in. wide were studied. The centre tube wall, submerged to various depths, formed the boiling surface. Observations suggested a convective heat transfer mechanism, and correlation by a Dittus‐Boelter equation form proved successful.
Determination of the activity coefficient of a volatile component in a binary system by gas‐liquid chromatography
Authors: Chueh Chun F. , Ziegler Waldemar T.
Published: June 2004

The gas‐liquid chromatographic (GLC) method of measuring the activity coefficient of the solute in a binary system has been extended from infinite dilution to the finite concentration range. An equation is presented relating the retention volume of the injected solute sample to the equilibrium solute concentration present in the column. This relation permits determination of the activity coefficient of the solute. Based on the experimental results obtained from the study of the two binary systems, benzene in diethylene glycol at 50°, 70°, and 90°C. and n‐hexane in 1,2,4‐trichlorobenzene at 30°C., the activity coefficients of the solute measured by the GLC method were found to agree within about ±5% with those obtained by the static equilibrium method.
Flash x‐ray analysis of fluidized beds
Authors: Romero Jacob B. , Smith Don W.
Published: June 2004

Flash X‐ray radiography was used to study the internal structure of fluidized beds. Basic data were obtained on the density distribution and on void shapes, sizes, and velocities within an air‐sand bed. The data obtained, in general, support the view of fluidized beds as consisting of liquidlike emulsions through which voids rise. Density measurements and void characteristics were in agreement with the two‐phase flow theory and with more recent theories of fluid bed flow. Void velocities and shapes agreed with recent predictions that the dense phase behaves as a liquidlike emulsion of zero viscosity and surface tension.
Dynamics of bullet shaped bubbles encountered in vertical gas liquid slug flow
Authors: Street James R. , Tek M. Rasin
Published: June 2004

A theoretical analysis is presented of the liquid film flowing around long, bullet shaped, gas bubbles which characterize the slug‐flow regime in two‐phase flow through vertical pipe. Integral mass and momentum balances on the liquid film allow the prediction of gas bubble shape, liquid holdup around the bubble, wall shear stress acting on the liquid film, and velocity profiles in the liquid film. These predictions are in good agreement with data available in the literature.
The numerical solution of boundary‐layer problems
Authors: Fussell D. D. , Hellums J. D.
Published: June 2004

A new method for numerical solution of boundary‐layer problems has greater applicability as well as greater speed and accuracy than the several previously proposed methods. The method uses the Goertler‐transformed equations and a nonlinear finite‐difference procedure. In most earlier work on difference methods the equations have been linearized at each step parallel to the boundary. The method of treatment of the boundary conditions on the equation of change for energy or mass transfer is shown to have an important influence on accuracy, and a new, more accurate method of treating boundary conditions involving the normal derivative is presented.

Typical complete solutions are compared with the several methods. The solutions include both similar and more general flows up to separation, as well as coupling between the momentum and energy‐balance equations.
Thermodynamic consistency tests for solid‐liquid equilibria
Authors: Null Harold R.
Published: June 2004

The technique of testing the validity of phase equilibria by applying thermodynamic consistency tests is highly developed for vapor‐liquid equilibria. The application to solid‐liquid equilibria, howerver, has been developed very little. The problems associated with thermodynamic consistency tests are discussed and a new technique for evaluating the validity of experimental data has been developed. Several possible test equations are presented and are applied to test the consistency of three sets of solid‐liquid equilibrium data.
Motion of gas bubbles in non‐Newtonian liquids
Authors: Astarita Gianni , Apuzzo Gennaro
Published: June 2004

The available theoretical knowledge of the motion of gas bubbles in Newtonian liquids is reviewed, and the possibility of extension to non‐Newtonian liquids, both purely viscous and viscoelastic, is studied. Experimental data on the rising velocities of gas bubbles in a variety of non‐Newtonian liquids are presented and interpreted on the basis of theoretical knowledge. Peculiarities that have been observed in highly elastic liquids are discussed, and a tentative interpretation is offered.
Isothermal activity coefficients for the system cyclohexane—n‐heptane—toluene at 25°C
Authors: Katayama Takashi , Sung Edmond K. , Lightfoot Edwin N.
Published: June 2004

Isothermal vapor‐liquid equilibrium data at 25°C are presented for the ternary and binary system containing cyclohexane, n‐heptane, and toluene. These data were obtained by static equilibration in the presence of diluent nitrogen by chromatographic analysis of the saturated vapor. The data obtained were of at least comparable accuracy to those available at the normal boiling point, and the procedure appears to offer several substantial advantages. Neither a priori prediction of activity coefficients from regular solution theory nor extrapolation of data taken at the normal boiling point is a satisfactory substitute for the isothermal data.
Sedimentation of dilute suspensions in creeping motion
Authors: Famularo Jack , Happel John
Published: June 2004

Solutions to the creeping motion equations for a cylinder and particles in an infinite media were superimposed to calculate the first‐order correction to the Stokes settling velocity for a particle inside a cylindrical container and for various models used to approximate the settling characteristics of dilute suspensions. The models were based on an assumed disribution of translating particles subject only to the hydrodynamic forces produced by their motion. Particle interactions and wall effects for ordered and random arrangements of spherical particles in a cylinder were calculated on a digital computer and used to devlop equations for settling velocity as a function of concentration.

The equations developed for the models containing spherical particles were modified to apply to nonspherical particles by considering each particle as a point force with regard to the fluid motion it produces at neighboring particles. As an application of these equations, a model of a dilute fiber suspension was studied in which prolate spheroide settle perpendicular to their symmetry axes.

The correction to Stokes' law for ordered arrangements of spheres is close to that obtained by earlier investigators working with similar models. However this correction leads to lower settling rates than the bulk of reported experimental data at any given particle concentration in the dilute range of less than 5% solids. The authors have shown that this discrepancy may be eliminated by assuming an alternate model composed of doublets in place of uniformly distributed particles. It may be concluded that in the dilute concentration range a model of a sedimenting suspension must include terms which reflect its tendency toward cluster formation and the consequent effect on settling rate. In order to accomplish this, forces other than hydrodynamic may have to be considered, for example, electrostatic forces.
Direct contact heat transfer with change of phase: Condensation of single vapor bubbles in an immiscible liquid medium. Preliminary studies
Authors: Sideman Samuel , Hirsch Gideon
Published: June 2004

Motion picture studies of condensation of isopentane bubbles rising in water elucidate the transfer mechanism involved in latent heat transport.

In general, two characteristic regions are noted. In the first region, up to some 80% liquid content, the bubbles deform and oscillate and heat is transferred by turbulent convection. In the second region the rate of transfer is controlled by the resistance of the condensed liquid, and heat is mainly by conduction. The effect of temperature differences between the bubble and the continuous phase (up to 3.5°C.) on the transfer coefficients could not be isolated, whereas that of the initial diameter of the bubble was quite marked.

The results are in agreement with those obtained in earlier studies of evaporating drops in immiscible liquids, indicating the similarity of the basic heat transfer mechanisms.
Heat transfer to evaporating refrigerants in two‐phase flow
Authors: Lavin J. Gerard , Young Edwin H.
Published: June 2004

Flow regimes occurring during evaporation of Freon‐12 (dichlorodifluoromethane) and Freon‐22 (monochlorodifluoromethane) inside five tubes were investigated. Two flow models are proposed, one each for vertical and horizontal tube orientation. The limits of each flow regime were determined and heat transfer correlations obtained. The most significant flow regimes were found to be nucleate boiling, annular flow, and mist flow. A correlation for the transition between annular flow and mist flow was obtained.
A two‐way capillary viscometer
Authors: Tzentis L. S.
Published: June 2004

A two‐way capillary viscometer for measuring shear rates from <0.01 to >1,000,000 sec.−1 at pressure drops up to 1,000 lb./sq.in. has been designed. It consists of a capillary tube mounted vertically between two sample reservoirs, of which the lower one is connected to a mercury manometer. The driving force, gas under pressure in a large tank, is connected to the upper reservoir and the manometer, thus allowing the sample to be moved in either direction through the capillary. The special feature of this viscometer is the indirect automatic measurement of bulk velocity of the fluid sample (3 to 20 cc.) in the capillary tube by means of a mercury manometer.

The precision of measurement of the velocity is one part in four hundred and can be maintained over the whole range of shear rates by the appropriate choice of the ratio of the diameter of the capillary and manometer tube.

Energy losses due to capillary heating and kinetic energy are given in terms of ΔP across the capillary. Couette end effect was found to be 0.3 diam.

A study of the rheology of polyacrylonitrile (PAN) in concentration range of ½ to 10½% PAN shows that the non‐Newtonian behavior and elasticity of PAN solution increases rapidly with concentration.
Heat transfer and reaction in laminar tube flow
Authors: Rothenberg R. I. , Smith J. M.
Published: June 2004

An analytical study was made of the temperature and composition distribution and heat transfer characteristics for a reacting fluid in a tube. The reaction was assumed to be first order and irreversible and the flow to be laminar.

The results, which consisted of radial and axial profiles of temperature, composition, and Nusselt number could be expressed in terms of four parameters. The gradient of radial composition was usually sufficient to judge the effect of reaction on the heat transfer coefficient. Owing to residence time and temperature effects, the Nusselt number even for an exothermic reaction was usually greater than that for an inert system. For endothermic cases, the energy flux due to diffusion increases the total energy flow, and the Nusselt number may be several fold that in the corresponding nonreactive system.

For certain values of the parameters the radial temperature and composition profiles showed maxima and minima between the wall and center of the tube. At these conditions the direction of the flow of energy due to diffusion could not explain the increase in Nusselt number.
Why thermodynamics is a logical consequence of information theory
Authors: Tribus Myron , Shannon Paul T. , Evans Robert B.
Published: June 2004

An observation of the properties of bulk matter necessarily omits many details of the motion of the particles which comprise that matter. If a communication regarding the observation is to be consistent, it must conform to certain rules which follow from the theory of information. An analysis of the problem of deciding upon a consistent encoding for such observations leads, as a unique result, to the concepts and equations of classical thermodynamics. The information‐theory analysis of this problem also leads to a better understanding of the basis for the “laws” of thermodynamics.
Height of a liquid film in a horizontal concurrent gas‐liquid flow
Authors: Cohen Leonard S. , Hanratty Thomas J.
Published: June 2004

Results of a study of the height of liquid films flowing concurrently with an air stream in a horizontal channel are presented. If three‐dimensional waves exist at the interface, the dimensionless film height h+ = hu*/v, defined in terms of the friction velocity and the kinematic viscosity of the liquid, is primarily a function of the liquid Reynolds number.
Vapor‐liquid phase behavior of the helium‐methane system
Authors: Sinor J. E. , Schindler D. L. , Kurata Fred
Published: June 2004

This report presents more extensive experimental vapor‐liquid equilibria data for the helium methane system than are found in the literature. A static sampling technique was used to obtain vapor and liquid compositions for six temperatures between −180° and −85°C. and pressures up to 2,000 lb./sq.in.abs. Data at 2,000 lb./sq.in.abs. were extended to the critical temperature of the mixture.

Average scatter of the data from the smoothed lines is approximately 1% of the helium concentration or 0.03 mole % helium, whichever is larger. Vapor compositions at −140°, −160°, and −180°C. were analyzed by a different technique and scattered on the average from the smoothed curve less than 4% of the methane concentration. Comparisons are drawn between the data of this study and the previously published work of Kharakhorin. The solubility of helium in liquid methane was found to be considerably less than the values indicated by Kharakhorin.

Experimental data are presented in tabular form and in various phase composition diagrams. The behavior of the helium‐methane system is seen to be very similar to that of the helium‐nitrogen system, with helium being much less soluble in methane than in nitrogen.

The data were satisfactorily represented by means of the Krichevsky‐Kazarnovsky equation. Extrapolations to higher pressures should be feasible.
The application of the Geddes fractionation index to crude distillation units
Authors: Gilbert R. J. H. , Leather J. , Ellis J. F. G.
Published: June 2004

The degree of separation effected by a fractionator can be measured by a fractionation index n. The index is the equivalent number of theoretical plates, operating at total reflux, which would effect the same component separation as the fractionator.

The value of the fractionation index is readily calculated from the Fenske‐Underwood equation when component analyses of the feed and products are available.

In the case of crude oils, the number of components is so great that resolution in the laboratory is not practicable, and the feed and products are customarily analyzed by high efficiency laboratory fractionators which give their true boiling point characteristics. In this form, the data have been broken down into short fractions which have then been treated as pseudo components in subsequent column calculations.

This paper presents a method for treating the product TBP curves as algebraic functions without the necessity for breaking the feed TBP data into arbitrary short fractions. The fractionation index can be derived directly from product TBP data, or the TBP data can be calculated when the fractionation index is known.

Data from performance tests on three commercial units have been analyzed. The TBP distillation analyses of the crude oils and the products enabled the fractionation indices pertaining to each section of the fractionators to be evaluated.
Axial mixing and extraction in a mechanically agitated liquid extraction tower
Authors: Bibaud Roger E. , Treybal Robert E.
Published: June 2004

Axial mixing was measured in both phases for a countercurrently operated, mechanically agitated extractor of the Oldshue‐Rushton design for water continuous and toluene and kerosene dispersed. Results in terms of an eddy axial diffusivity were correlated in terms of the variables studied. These correlations were then applied to column performance during extraction of n‐butyl amine from kerosene into water, and the true mass transfer coefficients, corrected for axial mixing, were determined. These are shown to be predictable for droplets of dispersed phase considered to be rigid spheres.
Particle migration in shear fields
Authors: Denson C. D. , Christiansen E. B. , Salt D. L.
Published: June 2004

The motion of a single rigid sphere entrained in a glycerine‐water solution flowing downward through a cylindrical tube has been investigated throughout a range of particle Reynolds numbers of 6.0 to 120.0, tube Reynolds numbers of 208 to 890, and particle‐to‐tube diameter ratios of 0.120 to 0.190. Trajectories of the sphere, calculated for various particle Reynolds numbers by using the Rubinow‐Keller expression for the transverse force, were found to agree satisfactorily with experimentally determined trajectories when the particle Reynolds number was below 40.0. In all cases the sphere was observed to migrate to the axis of the tube. At the lower particle Reynolds numbers the sphere approached the axis asymptotically, whereas at the higher particle Reynolds numbers the sphere oscillated across the axis of the tube one or more times during migration. All observations were made with spheres which were less dense than the fluid, the density difference being as high as 10% of the fluid density.
Reduction of single particles and packed beds of hematite with carbon monoxide
Authors: Osman M. A. , Manning F. S. , Philbrook W. O.
Published: June 2004

Sintered spheres of reagent grade hematite and particles of vermilion ore were reduced by carbon monoxide‐carbon dioxide mixtures over the temperature range 820° to 920°C. If all the weight loss were assumed to occur at a single hematite‐iron interface, then the early stages of reduction could be correlated by a series combination of the individual resistances due to boundary‐layer transport, transport through the reduced iron shell, and interfacial chemical reaction. Sintering and cracking affected the reduction at later stages. Particle reducibility, measured as rate of weight loss, was independent of particle porosity.

Packed beds of similar sized vermilion ore particles were reduced with carbon monoxide‐carbon dioxide mixtures at temperatures between 820° and 920°C. Barner's and Spitzer's methods of estimating fixed‐bed reduction rates and exit gas compositions were modified to include the multiple‐step, single‐particle kinetic models. The resulting predictions of fractional reduction agreed closely with the present data; however, theoretical and experimental exit gas compositions differed considerably.
Catalytic oxidation of hydrogen—intrapellet heat and mass transfer
Authors: Maymo J. A. , Smith J. M.
Published: June 2004

Rates of oxidation of hydrogen were measured by using platinum–alumina catalyst particles and 1.86‐cm. pellets. For high‐reaction rates, temperature differences between center and surface of the pellets were more than 300°C. Under these conditions large variations in temperature with position on the pellet surface were observed. The pellet reactor was of the recirculation, stirred‐tank type with injection nozzles. Local heat transfer coefficients between pellet and gas varied twofold with location on the surface. The data showed that intrapellet heat and mass transfer resistances were both important, while between pellet and gas only the heat transfer resistance was significant.

The effective thermal conductivity of the pellet was measured independently. By using this and the experimental temperature measurements, a new method s devised to establish the effective diffusivity under reaction conditions.

Effectiveness factors were predicted from ke and De and the rate data for the particles. The results were about 7% greater than the experimental effectivenes lactor.
Chemical reactions during rapid quenching of oxygen‐nitrogen mixtures from very high temperatures
Authors: Ammann P. R. , Timmins R. S.
Published: June 2004

A model has been developed to study chemical reactions which occur in oxygen‐nitrogen mixtures during very rapid cooling in small‐diameter tubes. The system considers both homogeneous gas phase reactions and surface reactions based upon a simplified mass transfer mechanism. With an energy balance used to determine the rate of quenching, the mole fractions of nitrogen, oxygen, nitric oxide, atomic nitrogen, and atomic oxygen were calculated as a function of temperature. In these studies, air and an equimolal oxygen‐nitrogen mixture were cooled from temperatures which ranged between 3,000° and 7,000°K. The calculations showed that when the gases were cooled at rates exceeding ten million degrees per second, the species did not follow a chemical equilibrium path during the quenching process. In cooling from 4,000° to 7,000°K. the computations show that consideration of surface reactions predicts greater nitric oxide yields in the quenched gas than for homogeneous reactions alone. In fact, the heterogeneous reactions must contribute to the overall chemistry of quenching air. The composition of the quenched gas is strongly dependent upon the temperature‐time history of the gas in the probe and upon the composition of the hot gas before it is quenched.
Stresses in concentrated polymer solutions: Part I. Shear dependence of viscosity
Authors: Williams Michael C.
Published: June 2004

A method is suggested for calculating stresses in sheared polymeric liquids. It synthesizes Kirkwood's correlation function techniques and Fixman's formulation for the stress tensor P. The dependence of P on powers of solute concentration, in the concentrated solution range, arises from a consideration of intermolecular forces. A non‐Newtonian viscosity, characterized by only two parameters (low shear viscosity limit ηo and time constant λ), is derived from simple choices of functions which appear in the expression for P.
Thermal conductivity of binary mixtures of carbon dioxide, nitrogen, and ethane at high pressures: Comparison with correlation and theory
Authors: Gilmore Thomas F. , Comings E. W.
Published: June 2004

A secondary thermal conductivity cell of the horizontal, concentric cylinder type was developed. The thermal conductivity of the pure gases nitrogen and ethane and approximately 20, 40, 60, and 80% binary mixtures of carbon dioxide, nitrogen, and ethane were determined at 75°C. to 3,000 atm. Several predictive techniques were investigated and recommendations are made.
Effect of axial diffusion of vorticity on flow development in circular conduits: Part II. Analytical solution for low reynolds numbers
Authors: Vrentas J. S. , Duda J. L.
Published: June 2004

An analytical solution based on a previously proposed entrance model is developed for the case of flow at low Reynolds numbers. Agreement between this solution and the published numerical solution at this Reynolds number limit supports the authenticity of the numerical solutions presented previously.
The control of nonlinear systems. Part I: Direct search on the performance index
Authors: Lapidus Leon , Luus Rein
Published: June 2004

A straightforward and simple algorithm is presented for obtaining the optimal control of nonlinear systems. This algorithm has many of the advantages of dynamic programming but not the disadvantage of excessive computer storage. A number of numerical examples are presented to show the versatility of the method.
Heat conduction with solidification in a stratified medium
Authors: Hrycak Peter
Published: June 2004

With the use of the heat balance integral method, a formula for the depth of solidification in a stratified medium is derived that applies to Newton's cooling at the surface, where the temperature of the cooling medium is variable. The presence of a surface layer with zero latent heat is given a special consideration. Comparison of the proposed formula with the direct field measurements and the calculations carried out by others shows a satisfactory coincidence. For the simplified boundary conditions, the formular reduces to a known analytical solution.
Generalized numerical solutions of freezing a saturated liquid in cylinders and spheres
Authors: Tao Luh C.
Published: June 2004

A numerical method and graphs of generalized solutions are presented for a moving interface problem of freezing a saturated liquid inside a cylindrical or a spherical container with a constant heat transfer coefficient, as well as melting a saturated solid. The frozen solid phase has a constant heat capacity.
Moments of the size distribution in radical polymerization
Authors: Katz Stanley , Saidel Gerald M.
Published: June 2004

For a number of polymerization models, we have developed equations that enable one to follow in time the moments of the polymer size distribution and the conversion. The exact and approximate solutions for the leading moments of the size distribution are presented for polymerization with initiation, propagation, and termination by combination. Approximate solutions for polymerizations with the additions of termination by disproportionation, chain transfer to monomer, and chain transfer to solvent show how these reactions decrease the average polymer size. From a simple model that exhibits autoacceleration a concomitant increase in the average polymer size also occurs.
Convective diffusion in a rectangular duct with one catalytic wall—laminar flow—arbitrary reaction order
Authors: Solbrig Charles W. , Gidaspow Dimitri
Published: June 2004

In a recent experimental study of reaction rates measured in a rectangular duct with a reaction of arbitrary order occurring on one wall, the results were analyzed in terms of an infinite parallel plate duct. The subject of this paper is the determination of the requirements necessary to treat a rectangular duct as a flat duct in the fully developed laminar flow regime. To this end, the rectangular duct problem is solved numerically. The results obtained show that mixing‐cup concentrations, average wall concentrations, and Nusselt numbers for any aspect ratio γ (between a square duct and parallel plates) may be estimated from the parallel plate results when a reduced distance is used. These parameters vary only slightly with aspect ratio. If the actual distance instead of this reduced coordinate is used, an aspect ratio of one to ten would be required to obtain results which are accurate to 6%. These conclusions are not valid for a catalytic reactor with four catalytic walls.
Heterogeneous and homogeneous reactions in a tubular reactor
Authors: Solomon R. L. , Hudson J. L.
Published: June 2004

Irreversible, first‐order, simultaneous heterogeneous and homogeneous reactions in an isothermal tubular reactor under laminar flow conditions are studied. Accurate values of the eigenvalues, eigenfunctions, and radial concentration profiles are found for the dilute system. Criteria are given as to when the homogeneous reaction may be neglected with respect to the heterogeneous reaction and vice versa. It is found that for a certain range of the rate parameters well‐known limiting solutions apply. Outside this range, the new solutions must be used.
Local and macroscopic transport from a 1.5‐in. Cylinder in a turbulent air stream
Authors: Galloway T. R. , Sage B. H.
Published: June 2004

The local and macroscopic thermal transfer coefficients were experimentally investigated for a 1.5‐in. copper cylinder located in a transverse flowing turbulent air stream. Measurements of local transport and pressure coefficient were made throughout the entire perimeter of the cylinder. The Reynolds number was varied from 2,600 to 86,000 and the free‐stream turbulence from 0.013 to 0.25. The estimated integral turbulence scale was found to vary from 0.3 to 0.5 in. over the range of conditions of flow investigated. The local transfer coefficient near stagnation increased 35% as a result of an increase in turbulance over the range indicated. Displacements of the locus of separation with varying Reynolds numbers and turbulence level were found.
Gas‐liquid mass transfer with a tangentially moving interface: Part II. Experimental studies
Authors: Byers Charles H. , King C. Judson
Published: June 2004

A horizontal, rectangular channel of high aspect ratio has been built for the study of interphase mass transfer in stratified, laminar gas‐liquid flow. Cases were examined where the resistance to mass transfer is confined to the gas phase and where the control is distributed between phases. Measurements of the rate of evaporation of ethanol into oxygen and carbon dioxide confirmed that cocurrent interface motion enhances gas phase‐controlled mass transfer coefficients substantially. On the other hand countercurrent motion of the interface decreases the coefficient. Agreement with basic convective diffusion theory was found for the evaporation of ethyl ether into helium and carbon dioxide from dilute solutions in ethanol, cases where the mass transfer control is distributed between the phases. Experiments with aqueous solutions were hampered by the accumulation of surfactants at the interface. A diaphragm cell technique was used to measure diffusivities of 0.87 × 10−5 sq.cm./sec. for ethyl ether at high dilution in ethanol and 0.96 × 10−5 sq.cm./sec. for ethyl ether at high dilution in water at 25°C.
On a tracer method for evaluating catalytic data
Authors: Kuo James C. W. , Wei James
Published: June 2004

This paper presents theoretical studies of a method of using a radioactive tracer technique to evaluate the kinetic data of heterogeneous catalytic reactions that are coupled with a Knudsen type of pore diffusion. By superimposing a transient radioactive tracer response over the steady state concentration profile in the catalyst particle, one can establish an implicit relation between the total amount of radioactive components diffused out of the particle and the kinetic data of the reaction system. This relation can then be used to evaluate kinetic data of the reaction system. A detailed study of general monomolecular complex systems is given. Use of the method for nonlinear systems is also included.
Kinetics of the aluminum‐chlorine reaction
Authors: Cozewith Charles , Li Kun
Published: June 2004

The reaction between aluminum, in the form of flat plates, and chlorine was investigated in a flow system at temperatures from 500° to 650°F. Gaseous aluminum chloride was the reaction product at these temperatures. At 500°F. the reaction proceeded by pitting, and the rate appeared to be chemically controlled. The reaction mechanism changed at higher temperatures to give a smooth reacted surface, and the reaction rate was found to be dependent upon both mass transport and kinetic parameters. The method proposed by Rosner for calculating mass transport‐dependent reaction rates was found to correlate both average and local rate data and was used to obtain estimates of the kinetic parameters for the heterogeneous surface reaction.
Laminar dispersion in capillaries: Part IV. The slug stimulus
Authors: Gill William N. , Ananthakrishnan V.
Published: June 2004

An exact analytical theory of the local behavior of finite slugs which are dispersed in three‐dimensional velocity fields is developed. It is shown that the dispersion coefficient enters the problem as an eigenvalue. For the important special case of fully developed straight pipe flow, considered first by Taylor and later generalized by Aris, the dispersion coefficient can be found very easily by the present method, which also provides the basis for studying a large class of more complicated problems.

A detailed numerical analysis is carried out to determine the limits of applicability of the analytical theory. Fortunately, it is found that dispersion of slug stimuli in fully developed laminar tube flow is described by Equation (15) when τ exceeds certain minimum values which depend only weakly on Peclet number and are independent of slug length in the region considered here. Since peak mean concentrations are predicated accurately by Equation (19) for X > 0.1, this is a convenient quantity to use to determine dispersion coefficients experimentally.

On comparing the numerical and analytical results for local point concentrations, good agreement is found, provided the average concentration is predicted accurately by Equation (15). This is significant because it implies that a broad class of difficult transient heat and mass transfer problems, with aperiodic inlet disturbances, can be solved by using superposition in conjunction with the present approach.
Some observations on the effect of interfacial vibration on saturated boiling heat transfer
Authors: Nangia K. K. , Chon W. Y.
Published: June 2004

An experimental investigation was carried out to determine the effects of vibration of the heat transfer surface in saturated pool boiling of water at atmospheric pressure. Wires of 0.01 in. diameter were heated electrically and vibrated electromagnetically at frequencies ranging from 20 to 115 cycles/sec. and amplitudes from 0.0118 to 0.0701 in. An increase in heat transfer up to a maximum of 200% at low ΔTwas observed for an increase in frequency and/or amplitude. At a heat flux of 105B.t.u./(hr.) (sq. ft.) high‐speed motion pictures were taken at 4,800 frames/sec. of a wire vibrating at 45 cycles/sec. with an amplitude of 0.0492 in. Comparison of these films with those taken at the same heat flux without vibration showed that the generating period and diameters at break‐off for the pulsed wire follow normal distribution. The waiting period is much longer and more fluctuating in nature. A slight increase in bubble emission frequency was also observed for pulsating wire.
High‐Pressure vapor‐liquid equilibria in ammonia‐water‐nitrogen‐hydrogen system
Authors: Guerreri Gianfranco
Published: June 2004

The results of ideal and nonideal vapor‐liquid equilibria of ammonia‐water‐nitrogen‐hydrogen, a system of industrial importance, have been examined. Redlich‐Kwong equation of state and the Gompertz equation have been used to determine the fugacities and activity coefficients in the vapor and liquid phases, respectively. The standard fugacity in the liquid phase is found by integrating the fundamental thermodynamic equation by using the Gamson‐Watson expression.

A trial and error procedure for the determination of a nonideal equilibrium system has been suggested. A comparison has been made between the available experimental values and the calculated ones. The importance of the use of fugacities which include deviations from ideality in calculating thermodynamic equilibria has been pointed out.
Pyrolysis of propane in a shock tube
Authors: Benson A. M.
Published: June 2004

The pyrolysis of propane has been studied over the temperature range 830° to 1180°C. with a single‐pulse shock tube employed to effect rapid heating and quenching. Both the uncatalyzed decomposition and the decomposition catalyzed by hydrogen sulfide were studied. First‐order rate constants for the uncatalyzed reaction are in excellent agreement with published data obtained in nonisothermal, tubular reactors. The product distribution differs from that obtained in other studies. It is characterized by decomposition of propane via two routes at roughly equal rates, one route leading to propylene and hydrogen, the other to ethylene and methane or ethane. Propylene subsequently is converted, almost stoichiometrically, to ethylene and acetylene. Hydrogen sulfide accelerates the initial decomposition of propane, thus maintaining high propylene selectivity to high propane conversion. A free radical mechanism is used to explain the gross features of the pyrolysis.
Measurement of coalescence frequency in an agitated tank
Authors: Howarth W. J.
Published: June 2004

A new method for measuring the frequency of coalescence of drops in an agitated tank is proposed. It makes use of the fact that the rate of establishment of a new steady state mean drop size following a reduction in agitation intensity is related to the coalescence frequency in the tank. This method allows independent examination of the effects of drop size and impeller speed on coalescence frequency, and has the advantage that, since the measurement is not dependent upon the addition of external substances, high degrees of purity can be maintained and the effect of trace additions to the dispersion observed. The results provide some support for the assumption of an inverse proportionality between coalescence frequency and drop size. For constant drop size, coalescence frequency was found to depend on impeller speed raised to the power of 1.3 to 1.65 and the volume fraction of dispersed phase to the power of 0.6. The magnitude of density difference between the phases and the operating temperature were found to affect coalescence frequency, although it is suspected that these two effects are interrelated. The addition of small quantities of simple electrolytes to the continuous phase was found to cause a marked reduction in coalescence frequency.
Polymer reactors and molecular weight distribution: Part I. Free radical polymerization in a continuous stirred‐tank reactor
Authors: Duerksen J. H. , Hamielec A. E. , Hodgins J. W.
Published: June 2004

An investigation was made of the simulation of bulk and solution polymerization of styrene in a continuous stirred‐tank reactor (CSTR). A theoretical model from the literature was used to predict conversion, molecular weight distribution (MWD), and molecular weight averages. The kinetic rate constants required to solve the model were also taken from the literature.

Styrene polymerizations were done at steady state in a laboratory‐scale CSTR over a range of experimental conditions. The recently developed gel permeation chromatograph (GPC) was used to measure MWD and average molecular weights. Comparisons were made between the theoretically predicted and experimentally determined values.

The effect of solvent was included in the theoretical model but further investigation is necessary before the effects of thermal polymerization, viscosity, and mixing can be included. Where the latter effects were not important, good agreement was obtained between theoretical and experimental values.
Permeation of vapors through polymers at low temperature and elevated pressures
Authors: Henley Ernest J. , Santos Marcos Luiz Dos
Published: June 2004

The permeation of propane, propylene, ethane, and ethylene through 0.0051‐cm. thick polyethylene films was measured at temperatures between 25° and −30°C. Plots ofPvs. 1/Tfor C3H8, C3H6, and C2H6were saucer shaped, the activation energies changing from positive (endothermic) to negative (exothermic) over a narrow temperature range. This change is attributed to a plasticization‐condensation phenomenon and a change in intermolecular potentials.
An improved version of the rate equation for molecular diffusion in a dispersed phase
Authors: Jury Stanley H.
Published: June 2004

A frequency domain analysis of reversible molecular diffusion in a granule or relatively stagnant drop of fluid reveals that for the larger values of time the rate equation reduces to

Compared with an earlier time domain result

the rate predicted is 15/π2 = 1.516 greater and this has been confirmed by results of experiment. An analysis of time constants shows that the dimensionless group relation

defines mathematically that which is meant by the larger value of time limitation.
An extension of the spline fit technique and applications to thermodynamic data
Authors: Klaus R. L. , Ness H. C. Van
Published: June 2004

The spline fit technique is extended to permit the smoothing of experimental data. It is applied to thermodynamic data which are otherwise difficult to treat.
Dirichlet problems for laminar forced convection with heat sources and viscous dissipation in regular polygonal ducts
Authors: Cheng K. C.
Published: June 2004

The effects of viscous dissipation on fully developed laminar forced convection with heat sources in various regular polygonal ducts under the thermal boundary conditions of uniform wall heat transfer per unit duct length and circumferentially uniform wall temperature are approached by the method of point matching. The method uses the exact solutions to the governing partial differential equations and satisfies the boundary conditions exactly only at selected points. This method complements the method of complex variables for various noncircular geometrical configurations where the velocity and temperature fields are not deducible directly from the boundary equations. The relationship between the average velocity and the average of (gradu)2over the cross section is pointed out. Other useful relationships between heat transfer quantities based on analogy or the observation of the results from literature and present investigation are also pointed out. The numerical results presented can be used to evaluate the effects of viscous dissipation on mean temperature, overall heat transfer rate at the boundary, heat transfer coefficient and Nusselt number. Graphical results for the representative cases are also presented for the heat transfer rate and the Nusselt number.
Separation of gas mixtures in free jets
Authors: Anderson James B.
Published: June 2004

Spatial distributions of species flux in axisymmetric free jets of helium‐argon mixtures were determined experimentally. The experiments encompass the transition range between inviscid and free molecular flow at the exits of the nozzles forming the jets. Comparison is made with existing theories of separation. The results confirm the validity of Sherman's predictions and Rothe's measurements of diffusive separation for nearly inviscid flow. In the transition range departures from the nearly inviscid theory occur. The maximum degree of separation is observed in this range.
Stability of naturally bounded nonlinear systems
Authors: Maurer Charles J. , Garlid Kermit L.
Published: June 2004

Liapunov's direct method is used to obtain regions of asymptotic stability for nonlinear systems with natural boundaries. In some cases this leads to larger stable regions of interest than if the bounds had been neglected. With account taken of the natural boundaries, a design method is formulated to find controller gains that give stable responses for anticipated disturbances. To compare the stability effects of different controllers and their gains, the change in the shape of the Liapunov function must be considered as well as the change in size of the region in which its time derivative is negative definite. Neglect of changes in the shape of the Liapunov function has led to misleading conclusions in previous work.
Multiphase viscoelastic flow through porous media
Authors: Slattery John C.
Published: June 2004

Local volume averaging of the equations of continuity and of motion over each phase in a porous medium is discussed. For a Noll simple material, inertial effects may be neglected with respect to viscous effects as the product of a Reynolds number with a Weissenberg number goes to zero (in the limit of a Newtonian fluid, inertial effects may be neglected as the Reynolds number goes to zero). When inertial effects can be neglected, a resistance transformation for each phase is introduced which in part maps the local volume‐averaged velocity vector into the local force per unit volume which that phase exerts on the pore walls and the moving phase interfaces. Capillary pressure is defined through a local surface average of the jump balance for momentum. The shape of the curve denoting capillary pressure as a function of saturation in a two‐phase flow may vary with the contact angle. For an isotropic multiphase flow of incompressible materials, the functional dependence of the resistance coefficient for a Noll simple material and for a Newtonian fluid is discussed by means of the Buckingham‐Pi theorem.
A mathematical model of a packed‐bed heat‐exchanger reactor for Dehydrogenation of Methylcyclohexane: Comparison of predictions with experimental results
Authors: Hawthorn R. D. , Ackerman G. H. , Nixon A. C.
Published: June 2004

The selective, highly endothermic reaction of methylcyclohexane to toluene and hydrogen was studied experimentally over a commercial Pt/Al2O3 catalyst, in an electrically heated tube serving as a packed‐bed reactor heat exchanger. The constant‐flux reactor, with measurement of temperatures within the bed at points intermediate along its length, proved well suited as an integral reactor for providing information on the reaction rate. A simple analytical model of the reactor was developed, and some of the data were used with the model to derive a rate expression.

The model gives a good representation of radial variation of temperature in the packed bed. In the region of high Reynolds numbers investigated, radial transport of enthalpy is described in the model by a film resistance at the tube wall defined by heat transfer coefficient, and a diffusive transport through the packing, dominated by eddy diffusion.
Direct contact heat transfer between immiscible liquids in turbulent pipe flow
Authors: Porter J. Winston , Goren Simon L. , Wilke Charles R.
Published: June 2004

This paper reports on an experimental study of the direct contact heat transfer between oil and water in turbulent pipe flow under nonboiling conditions. Data were taken by a new technique, namely, monitoring on a very fast response recorder the output of a small thermocouple placed in the two‐phase flow. The variables studied were the liquid velocity, the pipe diameter, the water volume fraction, and, to a lesser degree, the interfacial tension and the oil viscosity. A successful semiempirical method of correlating the data is also presented.
The synthesis of system designs: I. Elementary decomposition theory
Authors: Rudd Dale F.
Published: June 2004

A system synthesis principle is proposed from which processes can be composed to perform an assigned task. Synthesis is performed by the sequential decomposition of the design problem into subproblems which eventually reach the level of available technology.
Mechanism of interfacial mass transfer in membrane transport
Authors: Kaufmann Thomas G. , Leonard Edward F.
Published: June 2004

Dialysis of binary aqueous solutions of several sugars through a cellophane membrane was studied in a stirred batch dialyzer. Sherwood numbers describing mass transfer resistance in the fluid adjacent to the membrane were determined as a function of the corresponding Reynolds and Schmidt numbers. The results establish a reproducible environment for membrane testing in which a known controllable and small interfacial resistance is placed in series with that of the membrane. The results are also shown to support, for this geometry, the postulation of a third power relationship between eddy diffusivity and dimensionless distance from the phase boundary as well as the Sherwood‐Ryan nondimensionalization of this distance.
Catalytic dehydrogenation of cyclohexane: A transport controlled model
Authors: Graham R. R. , Vidaurri F. C. , Gully A. J.
Published: June 2004

Experimental data and a mathematical model for the dehydrogenation of cyclohexane on a platinum‐on‐alumina catalyst in the presence of excess hydrogen are presented. Differential rate data were obtained by using a fixed bed flow reactor over a temperature range of 400° to 500°C., and a pressure range of 21.3 to 41.8 atm. at modified Reynold's numbers of 20 to 65. Cyclohexane concentration was varied from 16 to 25 mole %. In the development of the basic model, complete transport control of the overall reaction rate with equilibrium at the fluid external surface interface is assumed. The average deviation between experimentally determined and basic model calculated rates was 5.65%.

Modification of the model by replacing the equilibrium assumption by a crude surface rate expression resulted in a reduction in average deviation to 4.3% and the maximum deviation was reduced from 22 to 12%.