bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass transfer across mobile interfaces
Authors: Angelo J. B. , Lightfoot E. N.
Published: June 2004

The dependence of extraction efficiency on flow distributions and droplet boundary‐layer behavior was investigated in a specially designed sieve‐tray extractor. Flow patterns and drop trajectories were obtained from residence‐time distributions and photographic observation. Extraction efficiency and continuous phase residence times were determined by a pulse technique.

For most runs, flow behavior could be adequately described by the assumptions of perfect mixing in the continuous phase and plug flow of the drop phase. However, drop velocities were higher than predicted by single drop correlations, and the flow pattern was sensitive to minor changes in operating conditions. Observed extraction efficiencies were in good agreement with predictions based on observed flow patterns and the two film, surface stretch, mass transfer model of Angelo and Lightfoot. Approximately 90% of the stage mass transfer effectiveness appears to be due to the drop rise period, and essentially all the remainder to drop formation for the stage geometry selected.

The greatest obstacle to reliable prediction of extractor performance is uncertainty as to the effect of operating conditions on flow distribution.
An introduction to the stability of distributed systems via a liapunov functional
Authors: Berger Albert J. , Lapidus Leon
Published: June 2004

Liapunov's direct method is extended to determine the stability of distributed systems with single and multiple equilibrium profiles. The method is simple to apply and makes use of certain inequalities to establish the sign definiteness of the time derivative of the Liapunov functional. Two numerical examples are presented, the adiabatic catalyst particle and an empty adiabatic tubular reactor with axial diffusion.
Tubular flow photoreactors for complex, nonchain kinetics
Authors: Harano Yoshio , Smith J. M.
Published: June 2004

The stationary state hypothesis, commonly used for intermediates in complex kinetics in batch reactor studies, is analyzed in a tubular flow photoreactor. For practical values of the rate constants for the chosen kinetic sequence, it appears that the hypothesis is valid over all but a short entrance region of the reactor for both streamline and plug flow models. Even though the stationary state is quickly achieved, for the normal range of diffusivities, the conversion to product may be affected by radial diffusion and velocity profiles.

In the course of the analysis the pertinent dimensionless parameters establishing the behavior of the reactor were identified. These arose from the differential equations expressing the conservation of radiant energy and mass in the system.
The dynamic behavior of a packed liquid extraction column
Authors: Doninger Joseph E. , Stevens William F.
Published: June 2004

The dynamic behavior of a packed liquid extraction column was investigated by comparing experimental frequency response data obtained from pulse testing with theoretical frequency response data. The theoretical model, which assumed that the column can be represented by a series of perfectly mixed cells, did not adequately describe the frequency response characteristics of the extraction process. However, by the utilization of various magnitude and phase correction factors, a technique was developed to obtain a semiempirical model that could be used to duplicate the actual performance of the liquid extraction column.
The steady state behavior of crystallizers with classified product removal
Authors: Han C. D. , Shinnar Reuel
Published: June 2004

Many industrial crystallizers incorporate some classifying devices. This paper deals with the steady state behavior of such systems. A method is described by which the particle size distribution can be calculated for any classifier, provided the crystallizer itself can be considered as a mixed vessel. The method is based on the use of residence time distribution and the escape probability or intensity function introduced by Shinnar and Naor. The effect of classification on crystallizer performance is discussed with the help of some illustrative examples.
Enhancement of film condensation rate on vertical tubes by longitudinal fins
Authors: Thomas David G.
Published: June 2004

Longitudinal rectangular fins loosely clamped to vertical tubes markedly increase the film condensation heat transfer coefficient. At a heat flux of 2×104B.t.u./hr.sq.ft., twelve ⅛×0.013 fins clamped to a ½ in. O.D. vertical tube 42 ½ in. long (thus doubling the surface area of the tube) gave a condensation coefficient of 15,000 ± 15% B.t.u./hr.sq.ft. °F. compared with 1,620 B.t.u./hr.sq.ft. °F. for the same tube without fins, a ratio ofh/hoof 9.2. The enhancement of the film condensation coefficient decreases as the heat flux increases and as the number of fins decreases.

A model based on the effect of fin shape on film and rivulet hydrodynamics explains the observed behavior.
The application of theoretical diffusion models in the presence of a catalytic reaction
Authors: Sterrett J. S. , Brown L. F.
Published: June 2004

The fundamental problem in this work was to determine if methods of predicting mass transport rates in porous catalysts, developed from theory in the absence of chemical reaction, are valid in the presence of reaction. By using the ortho‐para shift of hydrogen over a ferric oxide gel catalyst as the reacting system, the effective diffusivity within the catalyst was determined from kinetic data on five different particle sizes of the catalyst. This effective diffusivity was then compared with that predicted by three different procedures recently published. These procedures predicted diffusivities approximately 40% below the experimentally obtained diffusivity. Although the differences between the experimental and predicted effective diffusivities can be regarded as within the limitations of the accuracy of the predictions, the observed differences may also be caused by some form of surface transport.
Generalized solution of freezing a saturated liquid in a convex container
Authors: Tao Luh C.
Published: June 2004

Computer results of the required time to freeze completely a pure liquid in a container shaped like a slab, a cylinder or a sphere are correlated by equations which converge to the asymptotic solutions of the problem. Variables are grouped into dimensionless parameters so that these equations are applicable to any given system.
Correlations for adsorption of a binary gas mixture on a heterogeneous adsorbent—the methane‐ethane‐silica gel system
Authors: Masukawa Shigehiko , Kobayashi Riki
Published: June 2004

Correlations for the adsorption of a binary gas mixture on a heterogeneous adsorbent have been developed for both mobile and immobile models. Experiments determined the form for the expression of the surface heterogeneity, and only one dimensionless constant for the molecular size was required.

The correlations were tested by experimental data on the system methane‐ethane‐silica gel. For the same amount of adsorption the root‐mean‐square deviation of calculated versus experimental fugacity ranged from 4.1 to 5.2% for methane and from 2.7 to 3.4% for ethane at 5.0, 15.0, 25.0, and 35.0°C. for surface coverage ranging from zero to monolayer and for the complete composition range. The system at these conditions is classified as highly mobile based on examination of spreading pressure curves, both experimental and calculated based on the correlations.
Longitudinal dispersion of liquid flowing through fixed and fluidized beds
Authors: Chung S. F. , Wen C. Y.
Published: June 2004

Longitudinal liquid mixing in fluidized and fixed beds was studied using sinusoidal and pulse response techniques. The tracer used was light emissive fluorescein dye. A systematical study of liquid phase dispersion by varying particle size, fluid velocity, fraction voids, and particle density was conducted. A generalized correlation applicable to both fixed bed and fluidized bed was obtained. The application of the correlation in predicting the effect of the dispersion on reactor performance was discussed.
Effect of imperfect mixing on autorefrigerated reactorstability
Authors: Luben W. L.
Published: June 2004

This paper discusses the effects of imperfect mixing on the stability of autorefrigerated chemical reactors. Mixing is shown to strongly influence stability in these evaporatively‐cooled systems. A modified van Heerdensteady state stability analysis is presented. Computer simulation of a typical system illustrates the occurrence ofrunaways and local hot spots. Both continuous stirred tank reactors and batch reactors are considered.
Stability of numerical integration techniques
Authors: Distefano G. P.
Published: June 2004

This paper presents the cause of instabilities which arise during the numerical solution of ordinary differential equations. By using the numerical integration routines presently available, one actually approximates the differential equation by a difference equation. If the difference equation is of a higher order than the original differential equation, the approximate solution contains extraneous solutions which are not at all related to the true solution. It is the behavior of these extraneous solutions that one is usually concerned with in a stability analysis.

Also presented is a procedure for obtaining a bound on the largest allowable integration step size for a class of chemical engineering problems. A detailed explanation of the procedure is illustrated for unsteady state distillation calculations.
Effects of pore diffusion in the catalytic oxidation of ethylene
Authors: Caretto L. S. , Nobe Ken
Published: June 2004

Effects of pore diffusion in the catalytic oxidation of ethylene on copper oxide‐alumina have been studied by varying the catalyst size and maintaining constant the ratio of the tube to the pellet diameter. Hydrocarbon analysis was determined with a flame ionization detector; infrared analyzers were used to determine carbon monoxide and carbon dioxide concentrations. Other reaction products were analyzed with a gas chromatograph. Curvature of the Arrhenius plots and increase in reaction order with temperature indicated a transition region between kinetic control at lower temperatures and pore diffusion control at higher temperatures. A calculation procedure which was developed to predict the conversion considering pore diffusion effects provided satisfactorily agreement between calculated and experimental results.
On the particle size distribution function and the attrition of cracking catalysts
Authors: Gwyn J. E.
Published: June 2004

The rate of attrition of a catalyst sample, of a single particle size, can be expressed by a simple function of initial diameter and time. The initial rate is a function of initial diameter, whereas the decrease in attrition rate of a catalyst of a given size as it ages depends only on time.

The attrition equation for a single size of particles is introduced into the particle size distribution function and, through mathematical analyses, yields a relationship for the attrition of a full size‐range catalyst. The form of this relationship, which includes terms for attritability and severity of attrition conditions, is verified by laboratory and commercial attrition data on two full‐range catalysts. The size distribution of an attrited sample is not expressible in simple analytical form, but is readily obtained by numerical analysis.
Evaluation of drying schedules
Authors: Peck Ralph E. , Kauh Jae Y.
Published: June 2004

A generalized drying program that can simulate any drying conditions has been solved on a computer. The program includes the variation of humidity, temperature, and wind velocity over drying material. These three variables can be treated as functions of time. The correlations require knowledge of several basic properties of the material to be dried and were solved for the case of one directional heat and mass flow.

The computer calculated results are checked with experimental data. The effective diffusivity and the solid surface resistance to mass transfer were evaluated by data obtained in three experiments.

Solutions for constant drying conditions are presented in graphical form. Variations of such variables as humidity in a drier can be estimated from these curves but the computer program is more reliable.
Oxidation of hydrogen in a helium stream by copper oxide: Analysis of combined film and pore diffusion with rapid irreversible reaction in a fixed‐bed process
Authors: Scott Charles D.
Published: June 2004

Differential equations were derived to describe the system characterized by a rapid, irreversible reaction of a fluid species in a flowing fluid with a fixed bed of solids in which the reaction rate was controlled by mass transfer of the reacting fluid from the bulk fluid to the reaction site in the solid. Two kinds of mass transfer resistances were assumed, external or film diffusion resistance, and internal pore diffusion resistance. The set of differential equations were solved by a finite‐difference method for both the generalized case and for the specific case of reaction of hydrogen in a stream of helium with fixed beds of copper oxide pellets.

The hydrogen‐copper oxide reaction is one step in a proposed method for removal of hydrogen as a contaminant in the helium coolant of nuclear reactors. This reaction was experimentally investigated in tests with both differential and deep beds of copper oxide in the temperature range of 400 to 600°C., at pressures of 10.2 to 30.0 atm., with gas mass flow rates of 0.0050 to 0.050 g./sq.cm.‐sec, and with inlet hydrogen concentrations of 0.0008 to 1.21 vol. %. These tests showed that the system could be described by the two rate‐limiting steps: film and pore diffusion of hydrogen. Differential‐bed tests were used to establish hydrogen transport properties within the porous copper oxide pellets, and tests with deep beds were used to establish external mass transport properties.

Generalized breakthrough curves were determined by a computer solution of the mathematical model. These curves can be the basis for design of fixed‐bed copper oxide oxidizers for gas‐cooled, nuclear reactor purification systems and for design of any fixed‐bed system which follows the assumed reaction mechanism.
The growth of single crystals by controlled diffusion in silica gel
Authors: Rubin Bernard
Published: June 2004

Monocrystals of calcium tartrate tetrahydrate, neodymium‐doped calcium tartrate tetrahydrate, and cuprous chloride have been grown by controlled diffusion in silica gel using both metathetical and decomplexation reactions. Conditions for the optimum growth of the crystals are given and it is shown how the pH of the gel, the temperature of its formation, the concentration of the reactants which make up the gel, and the concentration of the reactants which result in the crystal are important in attaining good single crystal products. Crystals have been grown up to 11 mm. on edge in three to four weeks, and in many cases take on a form which, to all outward appearances, seem to have been cut and polished.
The effect of vapor distribution on distillation plate efficiencies
Authors: Furzer I. A.
Published: June 2004

The nonuniform distribution of vapor across a distillation plate causes a reduction in the Murphree plate efficiency. The magnitude of the reduction has been evaluated and the maximum effect occurs when the liquid mixing is intermediate between the perfectly mixed and the plug flow cases.
Oxidation‐reduction reactions in stirred liquid‐liquid systems
Authors: Mansoori G. A. , Madden A. J.
Published: June 2004

Oxidation‐reduction rates have been determined in stirred liquid‐liquid systems wherein tetravalent cerium ions in a continuous aqueous phase were reduced by tetrachlorohydroquinone contained in dispersed organic droplets. Kinetic data obtained (using low volume fractions (<0.06) of dispersed organic phase) indicate that the rate of reduction of ceric cerium is proportional to the extent of the interfacial area of the stirred liquid‐liquid system. Two possible rate‐limiting mechanisms are discussed to explain the observed kinetic behavior.

This liquid‐liquid electron exchange system might find potential use as a chemical tool for measuring changes in interfacial area as influenced by various mixing parameters.
Joule‐Thomson effects in gas mixtures: The nitrogen‐methane‐ethane system
Authors: Ahlert R. C. , Wenzel L. A.
Published: June 2004

Pressure‐temperature data were obtained along isenthalps for nitrogen, methane, and three ternary nitrogen‐methane‐ethane mixtures. These data were differentiated to obtain Joule‐Thomson coefficients over the temperature range from ambient to 200°K. and at pressures from 165 atm. to about 5 atm. Data for nitrogen was obtained down to 140°K.

The resulting Joule‐Thomson coefficients were compared with predictions based on the Beattie‐Bridgeman and Benedict‐Webb‐Rubin equations of state and on the virial equation of state truncated after the third virial coefficient. These comparisons show that the Benedict‐Webb‐Rubin equation could predict the data with a deviation averaging 1.7%. The Beattie‐Bridgeman predictions were highly dependent upon the mixture rules used, with the best set of mixture rules giving an absolute average deviation of 4.8%. Predictions using the virial equation with virial constants obtained from the Lennard‐Jones potential energy function using a geometric mean minimum potential energy deviated from the experimental data by 5%.

In all of these comparisons, the virial coefficients of ethane appear to be in greatest uncertainty, and the predictions of mixture data high in ethane least satisfactory. Thus it appears that improved data on the pure components, particularly ethane, are vital to any satisfactory evaluation of mixture properties.
Free volume theory for viscosity of simple nonpolar liquids. Part I. Pure components
Authors: Gubbins Keith E. , Tham M. J.
Published: June 2004

An improved free volume theory is presented, and is shown to predict the variation of viscosity with temperature and pressure satisfactorily for liquids composed of simple, nonpolar molecules, when the density is greater than twice the critical value. Allowance is made for the temperature dependence of the minimum free volume for a jump, and for the density dependence of the activation energy at constant volume. Corresponding states relationships are provided for these quantities, the reducing parameters being the temperature and molal volum at the melting point.
Physical properties of hydrogen sulfide‐water mixtures
Authors: Burgess Mitchell P. , Germann Raymond P.
Published: June 2004

Calculations concerning the production of heavy water by the hydrogen sulfide dual‐temperature exchange process require precise data on the physical properties of dry hydrogen sulfide and hydrogen sulfide‐water mixtures for temperatures between 25 and 170°C., and for pressures between 200 and 340 lb./sq.in.abs. However, data on enthalpy of hydrogen sulfide‐water mixtures were not found in the literature, and data published on hydrogen sulfide‐water compositions at equilibrium were given at such large intervals of temperature and pressure that they could not be interpolated accurately enough by ordinary means.

Specific volume and enthalpy of dry, superheated hydrogen sulfide vapor,

Composition of hydrogen sulfide‐water vapor and liquid in equilibrium,

Enthalpy of hydrogen sulfide vapor saturated with water vapor,

Enthalpy of water liquid saturated with hydrogen sulfide vapor,

Deuterium distribution constants for vapor‐liquid equilibrium.

A study was undertaken to express the properties, listed below, with equations suitable for solution on a digital computer and useful in mathematical models of the process.

New correlating constants were derived where needed. The equations and typical results are presented in this paper.
Numerical optimization of large interconnected systems
Authors: Davison E. J. , Alas R.
Published: June 2004

This paper describes a numerical procedure for optimizing a large set of interconnected systems with respect to a given index of performance. The method automatically constructs the vector differential equation of the complete system from (a) the vector differential equations describing the behavior of the components of the system and (b) the manner of their interconnection. A hill‐climbing method is then used to select optimum values of the system's parameters to maximize a given index of performance. An example of the procedure applied to a high order system is included.
Optimal control of tubular reactors. Part I. Computational considerations
Authors: Chang K. S. , Bankoff S. G.
Published: June 2004

The necessary conditions for optimization of a system governed by a nonlinear vector first‐order partial differential equation with two (space and time) independent variables, such as governs the unsteady behavior of tubular flow reactors, are derived. Rather general objective functionals and boundary conditions, such as the recycle of unconverted reactant with an appropriate time delay for separation and a free choice of final time, are allowed. A gradient technique in control space is formulated, and it is shown that distinct computational advantages can accrue from the use of the method of characteristics.
Turbulence phenomena in drag reducing systems
Authors: Seyer F. A. , Metzner A. B.
Published: June 2004

An analysis based on the Townsend‐Bakewell model of the eddies in the wall regions of turbulent shear flows shows that viscoelastic fluid properties must lead to significant reductions in the rate of production of turbulent energy. This analysis in turn leads to the proper form of the similarity laws for drag reducing fluids, heretofore deduced empirically.

Measurements of the axial and radial turbulence intensities for flow through smooth round tubes are reported, as are measurements of the time‐averaged velocity profiles and the drag coefficients. These indicate that for solutions exhibiting drag reduction at all Reynolds numbers the flow may be transitional to Reynolds numbers of the order of 105. This transitional flow consists of alternating patches of laminar and turbulent fluid, within each of which the flow characteristics are approximately similar to those of Newtonian fluids. At high Reynolds number conditions with the turbulent field fully developed the velocity profile in the core is flatter under drag‐reducing conditions than for turbulent Newtonian fluids, a change dependent on the increased isotropy of the turbulent field of the drag‐reducing fluid. These effects appear to be a result of increases in the time scales of the radial fluctuations caused by the fluid properties.

Design calculations based upon the present results suggest that in large diameter pipelines, or in boundary layers on large objects, drag reduction may not be attainable under conditions of practical interest until fluids having relaxation times an order of magnitude larger than those presently available, but with comparable viscosity levels, are developed or, alternately, until fluids exhibiting Weissenberg numbers which do not change with deformation rate, can be found.
Mutually dependent heat and mass transfer in laminar duct flow
Authors: Sparrow E. M. , Chen T. S.
Published: June 2004

An analysis is performed of the strongly coupled heat and mass transfer processes which result from sublimation of mass from the walls of a duct into a flowing gas, the latent heat being provided solely by convective transfer from the gas. The flow is assumed to be laminar and hydrodynamically developed. Results are given for the streamward variations of the bulk and wall temperatures and mass fractions, of the heat and mass transfer rates, and of the local heat transfer coefficient. Representative temperature and mass fraction profiles are also presented. Entrance lengths characterizing the near approach to fully developed conditions are tabulated. Comparisons are made of the present results (based on a parabolic velocity profile) with those based on a slug flow velocity profile. A subsidiary analysis using the Lévěque model is also performed and the results compared with those of the principal solution.
Laminar, nonisothermal flow of fluids in tubes of circular cross section
Authors: Christiansen E. B. , Jensen Gordon E.
Published: June 2004

Numerical solutions of the equations of motion and energy are presented in the form of pressure‐loss, flow‐rate relationships for the laminar, nonisothermal flow of Newtonian and non‐Newtonian fluids being heated and cooled in tubes at constant wall temperature. The flow properties are represented by a temperature‐dependent form of the power law equation. The numerical results are shown to be in good agreement with experimental data for a wide range of fluid properties and flow conditions.
Adsorption of carbon monoxide‐nitrogen, carbon monoxide‐oxygen, and oxygen‐nitrogen mixtures on synthetic zeolites
Authors: Danner R. P. , Wenzel L. A.
Published: June 2004

Experimental results for the adsorption of the binary gas mixtures oxygen‐nitrogen, oxygen‐carbon monoxide and nitrogen‐carbon monoxide on two synthetic zeolites are reported. In all of these experiments the temperature was −200°F. and the total pressure was 1 atm. Also reported are the isotherms for the three pure gases on the two zeolites at −200°F. The results indicate that these zeolites have a surface selectivity which is independent of any sieving effect based on the size of the adsorbed molecules. It does not appear that the strong separations obtained can be explained in terms of the van der Waals forces which are generally believed to be dominant in physical adsorption. The available methods of predicting binary adsorption data from the pure gas isotherms have been examined.
The effect of surfactants on the flow characteristics of falling liquid films
Authors: Strobel W. J. , Whitaker Stephen
Published: June 2004

Experimental values of the wave length and wave velocity have been obtained for dilute solutions of valeric and hexanoic acid for a vertical falling liquid film. The wave length was unaffected by the surfactants for Reynolds numbers in the range 5 to 100; however, the wave velocity was decreased for increased surface concentrations of the two acids. This is in direct contradiction to previous theoretical work, and the explanation for the anomaly is that the free surface velocity is greatly retarded by the adsorption of the surface active agents. In an effort to determine the extent of this retardation, an approximate form of the diffusion equation and the equations of motion were solved subject to boundary conditions describing the effect of the absorbed surfactant on the surface stress. The results indicate that the entrance length can be increased several orders of magnitude by the addition of small amounts of surfactant.
Creeping flow past a fluid globule when a trace of surfactant is present
Authors: Wasserman Melvin L. , Slattery John C.
Published: June 2004

The effects of a trace quantity of a surface‐active agent on creeping flow past a bubble or droplet are investigated. The equations describing mass and momentum transfer are simultaneously solved by a perturbation technique, consistent with the jump mass and momentum balances at the phase interface. The stream function for the velocity distribution is evaluated as an infinite series of spherical harmonics. Galerkin's method, which reduces the partial differential equation of continuity to a set of ordinary differential equations, is used to evaluate the concentration distribution of surfactant.

A sample calculation is carried out for relative motion between an air bubble and an infinite body of water which contains a trace of isoamyl alcohol. The relative velocity of the water at an infinite distance from the bubble is found to be highly sensitive to small changes in surfactant concentration from zero, although the bubble varies imperceptibly from a spherical shape.
Low Reynolds number developing flows
Authors: Atkinson Bernard , Brocklebank M. P. , Card C. C. H. , Smith J. M.
Published: June 2004

Equations are given that relate the entrance length to Reynolds number for pipe and channel geometries with a flat velocity profile as the initial condition. These equations are linear combinations of the creeping flow and boundary layer solutions. The former is obtained by minimization of the viscous dissipation using the finite element method. The equation for the pipe entrance is shown to be in good agreement with experimental data.
Copolymerization and terpolymerization in continuous nonideal reactors
Authors: Szabo T. T. , Nauman E. B.
Published: June 2004

A simple means for predicting composition distributions in copolymers is used to illustrate the strong influence of segregation effects in the reactor. A recycle loop reactor can be used to produce uniform copolymers by narrowing the macroscopic composition distribution, but there is a limiting microscopic distribution which results from probabilistic effects.
A study of the effects of internal rib and channel geometry in rectangular channels. Part I. Pressure drop
Authors: Buonopane Ralph A. , Troupe Ralph A.
Published: June 2004

Plexiglas models of rectangular channels were fabricated with various rib shapes to determine the effects of rib and channel geometry on the pressure drop. Pressure drops in twenty‐four individual variations of channel geometry were investigated using plexiglas models.

From this investigation, an empirical correlation for the pressure drop across the ribbed section of the channel was determined as a function of the linear fluid velocity and the geometric characteristics of the channels. This empirical correlation involves functions of seven geometric parameters of rib pattern and channel geometry.

Ribbed section pressure drops for commercial plate heat exchanger channels were predicted using the geometric characteristics of the commercial plates with the empirical correlations developed from the plexiglas channel studies. The total pressure drop for commercial channels was predicted by adding an average entrance and exit pressure drop to the predicted ribbed section pressure drop.

The correlations developed in this work allow one to determine the pressure drop in a ribbed rectangular channel from the geometric characteristics of the ribs and the channel in question.
The flow characteristics of swirl (centrifugal) spray pressure nozzles with low viscosity liquids
Authors: Dombrowski Norman , Hasson David
Published: June 2004

A study has been made of the mechanics of flow of low viscosity liquids through swirl spray nozzles. Discharge coefficients and spray angles have been measured for a series of nozzles designed to systematically determine dimensional effects not predicted by frictionless theory, in particular the effect of the ratios of swirl chamber diameter to orifice diameter and of orifice length to orifice diameter. It was found that a unique relationship exists between discharge coefficient and spray angle dependent only upon the value of the orifice length/diameter ratio. This result has been explained on the basis of an ideal flow theory extended to take into account the frictional decay of the vortex motion. A general expression has been derived which permits correlation of the flow characteristics of nozzles covering a wide range of designs.
How to manage your information, Bart E. Holm, Reinhold, New York (1968). 292 pages
Authors: Newton R. H.
Published: June 2004

No Abstracts.
Prediction of the first normal stress difference in polymer solutions
Authors: Meister Bernard J. , Biggs R. Dale
Published: June 2004

Shear stress and first normal stress difference data are presented for several polymer solutions undergoing steady shear rates from 1.0 to 100,000 sec.−1. The steady shear response is divided into three regions as a function of increasing shear rate. These are the diffusion controlled linear region, a moderate shear rate region where shear controls the entanglement‐disentanglement process, and a high shear rate region where aggregation of polymer molecules occurs. The transitions between the three regions are clearly illustrated by using a group designated as the rotation rate function.

A molecular model is derived for the shear controlled region that allows prediction of the first normal stress difference from the viscosity function and one additional constant that depends only on the molecular species. The White‐Metzner equation is found to adequately describe the aggregation region at high shear rates.
An experimental study of steady state multiplicity in a loop reactor
Authors: Root R. B. , Schmitz R. A.
Published: June 2004

Steady state multiplicity in an adiabatic loop reactor was studied in experiments employing the reaction between sodium thiosulfate and hydrogen peroxide in aqueous solution. The steady state characteristics of the loop reactor were predicted by a method which utilized batch reactor data of temperature vs. time directly. The method was based on the assumption of plug flow with negligible axial dispersion and on a single‐step chemical kinetic model. Experimental results verify the existence of multiple steady states on ranges of feed flow rates and recycle ratios and demonstrate the capability of the simple model for predicting the qualitative and quantitative features of the reactor steady state.

Some observations were made of the effect of large disturbances on the stability of the reactor while operating in a multiple state region. Results for such cases illustrate reactor instability in the sense that a transition to a new steady state takes place provided the disturbance is sufficiently large.
On the structure of dissolving thin liquid films
Authors: Suciu D. G. , Smigelschi Octavian , Ruckenstein Eli
Published: June 2004

The structure of thin circular films, formed over a flat water surface during the dissolving (influenced by surface forces) of isobutanol, is examined by performing film thickness and surface velocity measurements. The thicknesses were obtained by light absorption determinations, and the velocities by a stroboscopic method. The film profiles and the dynamic wetting angles obtained differ markedly from those corresponding to a static lens. This is explained by considering the equilibrium between dynamic surface tensions instead of that between static surface tensions.
Physical effects in red blood cell trauma
Authors: Nevaril C. G. , Hellums J. D. , Alfrey C. P. , Lynch E. C.
Published: June 2004

Red blood cell damage and destruction are important problems in the use of artificial valves, heart‐lung machines, and other devices which pump or process blood. An experimental study has been made on the mechanism of cell damage. Damage was defined by three types of observations on blood which had been subjected to trauma: (a) release of hemoglobin from cells (hemolysis), (b) morphological changes observed microscopically, and (c) red cell life span studies in rabbits using a Cr51 tagging technique.

Three types of physical forces which might be injurious to red cells were studied; shearing stress (of known, constant magnitudes from a concentric cylinder viscometer), pressure variations (from studies in a static pressure cell), and direct impact of solid surfaces (from studies in a device which simulates the seating action of artificial heart valves).

The study shows that high shearing stress may be primarily responsible for mechanical cell damage under certain important circumstances. There is a critical shearing stress above which cell damage increases markedly. Much of the cell damage does not appear as an immediate release of hemoglobin. Many cells undergo morphological changes and exhibit shortened average life span in vivo. The morphological changes due to shearing stress are very similar to the changes observed in patients who have hemolytic anemia associated with artificial valves.
Base film over which roll waves propagate
Authors: Woodmansee Donald E. , Hanratty Thomas J.
Published: June 2004

The liquid that moves along the duct walls in the annular regime observed in gas‐liquid flows often consists of a series of flow surges (roll waves) moving over a thin liquid film (base film). At a given gas velocity there is a critical flow rate of the liquid below which roll waves are not present. Measurements of the height and wall stress are presented to support the notion that the conditions in the base film are close to those which exist at the critical liquid flow rate.
Temperature—separation factor relationships in gaseous diffusion
Authors: Tock R. W. , Kammermeyer Karl
Published: June 2004

A theoretical equation was developed to predict the enrichment produced by a single stage porous Vycor diffusion cell as a function of temperature. The separations of five binary gas mixtures were measured experimentally over a temperature range of 80 to 600°K. The agreement between theoretical predictions and experimental results was good over most of the temperature range. The largest deviations occurred when the operating temperature approached the critical temperatures of the gases. Mixtures of oxygen‐carbon dioxide and helium‐nitrogen were observed to become nonseparative at predicted temperatures. Overall, both separation and separative capacity were observed to increase with a decrease in temperature.
Mass transfer at the solid‐liquid interface for climbing film flow in an annular duct
Authors: Sutey A. M. , Knudsen J. G.
Published: June 2004

A method utilizing a diffusion controlled electrochemical reaction was used to measure average and instantaneous mass transfer coefficients at the solid‐liquid interface in upward gasliquid climbing film flow in a vertical annular duct. These measurements give some indication of the mechanics of flow of the film, the extent of turbulence at the inner wall, and the effect of film thickness and wave motion on the mass transfer process at the inner wall. Predictions of incipient downflow of the film, shear stress at the inner wall, and interfacial shear stress were obtained from these measurements. Fluctuations in the velocity gradient at the inner wall were also studied. Results of this study are in good agreement with previous work and with theoretical predictions based on simplified momentum balance concepts.
A method for measuring particle diffusivity in two‐phase flow in the core of a duct
Authors: Briller Richard , Robinson Myron
Published: June 2004

A relatively simple, reliable means is described for measuring particle diffusivity in a particlefluid system in the core of a duct. Particles are injected into the midstream of the duct from a line source positioned normal to the direction of fluid flow. Particle diffusivity is calculated from measurements of the standard deviations of the particle concentration profiles at various downstream distances from the injector. At an air velocity of 10 ft./sec. under room conditions, 1μ oil droplets are found to exhibit a diffusivity of about half that of air alone under the same conditions.
Effects of surfactants on mass transfer inside drops
Authors: Huang W. S. , Kintner R. C.
Published: June 2004

A model is presented to account for reduced mass transfer to drops falling through a continuous phase which contains a surface active agent. The fluid flow patterns are essentially laminar. The reduction in mass transfer is said to be due to a reduction in available interfacial transfer area and to changes in both velocity and pattern of internal circulation. These are shown to be functions of contact time and can be characterized. Experimental values agreed with the theoretically predicted ones with a deviation of less than 10%.
Effect of Longitudinal Diffusion in Reverse Osmosis
Authors: Ohya Haruhiko , Sourirajan S.
Published: June 2004

No Abstracts.
Thermal physics, Edward A. Desloge, Holt Rinehart and Winston, New York (1968). 363 pages
Authors: Lewis James L. , Gaggioli Richard A.
Published: June 2004

No Abstracts.
Diffusion in pulsating flow in a distensible conduit
Authors: Fagela‐Alabastro Estrella B. , Hellums J. D.
Published: June 2004

An earlier study on interphase mass transfer in pulsating laminar flow has been extended to the case of a distensible tube. The physical situation studied corresponds to developed flow in a long tube with a traveling pressure wave of small amplitude impressed on the steady flow. The tube wall is free to expand radially. Asymptotic solutions are developed for large and small values of the frequency parameter. The interphase flux is much greater in distensible conduits than in the corresponding case in rigid conduits.
Heat transfer to solid‐vapor mixtures of cryogens below their triple points flowing through heated tubes
Authors: Jones M. C. , Giarratano Patricia J. , Simpson A. U.
Published: June 2004

Data are presented for wall temperatures and heat transfer coefficients for solid‐vapor mixtures of parahydrogen and nitrogen flowing in an electrically heated straight tube of length 40 times its diameter. These are interpreted by the application of flat plate, constant property boundary‐layer theory to models in which the solid particle geometrical distribution takes on simple limiting forms. The observed enhancement of the heat transfer coefficient over that for gas alone traveling at the same velocity is qualitatively predicted as a function of a dimensionless heat flux, the Sterman parameter qw/ρvUλ.
The use of positive feedback control systems to improve reactor performance
Authors: Gaitonde N. Y. , Douglas J. M.
Published: June 2004

Positive feedback control systems sometimes can be used to make stable chemical reactors generate periodic outputs. For one set of system parameters the time average conversion obtained from the oscillating reactor was approximately 20% higher than the economic optimum steady state value; for another case the time average operating cost was approximately 5% lower than that corresponding to the optimum steady state design. A general method for predicting when an improvement can be obtained is presented.
A digital simulation of transient oxygen transport in capillary‐tissue systems (cerebral grey matter). Development of a numerical method for solution of transport equations describing coupled convection‐diffusion systems
Authors: Reneau Daniel D. , Bruley Duane F. , Knisely Melvin H.
Published: June 2004

The mechanism by which oxygen is transported from capillaries into tissue for cell respiration has been a subject of interest since the work of August Krogh in 1919. Mathematical analyses of the diffusion process have been obtained by several investigators (11, 12, 18), but are limited in scope by the complicated nature of the problem. However, the solutions that exist give enough insight to inspire a more rigorous treatment. With the advant of electronic computers more complete analyses are now within reach (16).

The human brain accounts for less than 4% of the total body weight, yet it uses 15 to 20% of the total body oxygen consumption. This high metabolic rate makes the brain particularly vulnerable to any change in the normal oxygen supply. The fact that following a cessation of cerebral blood flow, unconsciousness develops within 10 sec., and irreversible damage within 10 min., demonstrates the importance of understanding the dynamics of oxygen supply to the brain.
The limiting form of the eddy diffusivity close to a wall
Authors: Notter R. H. , Sleicher C. A.
Published: June 2004

No Abstracts.
Improved withdrawal theories for cylinders by a more accurate description of curvatures of static menisci
Authors: Tallmadge John A.
Published: June 2004

No Abstracts.
The reduction in heat exchanger effectiveness caused by dilute quantities of drag reducing substances
Authors: White D. A.
Published: June 2004

No Abstracts.
Viscoelasticity in shearing and accelerative flows: A simplified integral theory
Authors: Adams E. B. , Bogue D. C.
Published: June 2004

An explicit, four‐constant model for viscosity and normal stresses in simple shear has been developed by simplifying the integral theory of Bernstein, Kearsley, and Zapas. In essence the procedure involves curve‐fitting the linear relaxation spectrum. The four constants appear also in equations for the stress distribution and for pressure drop in accelerative flow between flat plates; flow along rays is assumed. The equations reduce to second‐order theory and to Newtonian theory as a Deborah number becomes small. Comparison of the predicted stress distributions with previously published stress birefringent data shows good agreement; because of the low shear rates, however, the check is not demonstrating very strong departures from the second‐order asymptote. Certain other theoretical results, including pressure drop predictions, are also noted.
Evaporation rates of volatile liquids in a laminar flow system: Part II. Liquid mixtures
Authors: Clark Michael W. , King C. Judson
Published: June 2004

An approach has been developed for predicting rates of interphase mass transfer under conditions of high flux and high concentration level. A rectangular channel device has been used to measure rates of evaporation of four solutes, carbon disulfide, n‐pentane, cyclopentane, and ethyl ether, from n‐tridecane into flowing nitrogen. The evaporation rate of carbon disulfide agreed with the prediction of the interphase theory up to a carbon disulfide mole fraction of 0.30 in the bulk liquid. For the other three systems, a concentration gradient induced, surface tension driven cellular convection served to increase liquid‐phase coefficients substantially. A correlation was obtained for the effect of this cellular motion on the liquid‐phase mass transfer coefficient.
Mass transfer in a nonuniform impinging jet: Part I. Stagnation flow‐velocity and pressure distribution
Authors: Scholtz M. T. , Trass Olev
Published: June 2004

A theoretical solution for the impingement flow of a jet with a parabolic velocity distribution is given. Viscous generation and diffusion of vorticity in the jet were neglected. Experimental velocity and pressure distributions measured in an impinging jet of air originating with Poiseuille flow compare well with theory, thus justifying the assumption of inviscid flow. Pressure distributions on the deflecting surface were independent of nozzle height in the range 1 to 12 nozzle radii. For lower nozzle heights the effect of the constriction of flow between the nozzle and the surface followed the predicted behavior.
On the temperature field of a square column embedding a heating cylinder
Authors: Shih F. S.
Published: June 2004

An analysis of the two‐dimensional temperature field of a square column embedding a heating cylinder is presented. The analysis leads to a solution in finite series which gives rise to rapidly converging numerical results. The series coefficients computed for the extreme case of the cylinder being a line find a way of parametrization, which then furnishes the solutions for finite cylinders up to the case of the cylinder diameter being half of the column thickness. Results in five‐digit accuracy are presented. The method is simple and direct. In addition, it retains the same concise formal solution for a variety of boundary conditions.
Transitional flow in concentric annuli
Authors: Rothfus R. R. , Newby R. A.
Published: June 2004

A general means is proposed for predicting transitional velocity patterns in concentric annuli and between parallel plates from behavior in tubes. As in laminar and turbulent flow, transformations of space coordinates yield identical profiles under specific conditions of comparison. Predictions are confirmed by published data and can be related to recent theoretical proposals.