bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Solutions of an Initial Boundary Value Problem for the Euler-Poisson-Korteweg System
Authors: Zhang Xian
Published: February 2024

The Euler-Poisson-Korteweg system is a mathematical model arising from hydrodynamics and quantum hydrodynamics. It can be used to describe at interface the ow of capillary ows, such as the liquid-vapor mixture. In this paper, we obtain the global existence of solutions for high-dimensional compressible Euler-Poisson-Korteweg systems with small initial values by the energy method. The study can provide a theoretical basis for the development of efficient numerical solution methods, as well as contribute to the further study of other properties of the solution such as vibrational and bursting properties.
Anti-Inflammatory Effects of Nanoparticles Containing Alpha-Humulene in a Model of Alzheimer's Disease
Authors: Wendler Sabrina Aparecida , Nunes Jéssica Roberta , Dranski Lais Fernanda , Cordeiro Maria Elvira Ribeiro , Mainardes Rubiana Mara , Machado Christiane Schineider , Bini Ana Carolina Dorigoni , Schiewe João Alfredo , Miranda Livia Hoyer Garcia , Kerppers Ivo Ilvan
Published: February 2024

Alzheimer's disease (AD) is a neurodegenerative disorder that causes impairment in daily living activities. Although there is no consensus on the pathophysiology of this disease, neuroinflammation is known to be associated with this disease. Objective: To evaluate the anti-inflammatory effects of nanoparticles containing alpha-humulene (HUM) in an experimental model of AD. Methodology: Thirty-three animals were included in the sample, 3 of which were in the negative control group. The other 30 patients received the amyloid-beta peptide in the CA1 region of the hippocampus for neuroinflammation. The cells were allowed to rest for 30 days for the inflammatory process to occur. The HUM group was treated with α-humulene particles, the NHUM group was treated with α-humulene nanoparticles for 15 days, and the CP group was not treated. Results: There were significant differences in IFN concentrations between the CP and CN (p=0.0001), HUM and CN (p=0.0003), CP and NHUM (p=0.0006), and HUM and NHUM (p=0.0495) groups. There was no difference in TNF-α levels between the groups. IL-6 levels were significantly different between the CP and NHUM groups (p=0.0078) and between the CP and CN groups (p=0.0009). IL-12 levels were significantly different between the CP and CN (p=0.0001) and between the NHUM and CN (p=0.0160). Overall, the highest concentration was in the CP group. Concerning IL-10, there was a difference between the CP and NHUM (p=0.0003) and between the NHUM and CN (p=0.0005), with the NHUM having the highest concentration. Immunohistochemistry analysis of the anti-Tau and anti-GAPF antibodies revealed strong positivity in the CP group, positivity in the HUM group, and weak positivity in the NHUM group. Conclusion: Treatments for Alzheimer's disease and HUM and NHUM were effective.
Mass transfer in packed beds
Authors: Fahien R. W. , Smith J. M.
Published: June 2004

Although considerable work has been done on the problem of heat transfer radially in fixed beds through which gases are flowing, the data available for mass transfer are limited to one pipe size and one packing size and refer to average diffusivities for the entire bed. The present study was undertaken to determine: (1) diffusivities over a range of pipe and packing sizes and (2) the effect of radial position in the bed.

The measurements were made by introducing carbon dioxide into an air stream and analyzing the resultant mixture at various positions in the bed downstream from the point of injection. Pipe sizes of 2, 3, and 4 in. were packed with spherical particles of 5/32‐, 1/4‐, 3/8‐, and 1/2‐in. nominal diameter.

The differential equation describing the concentration in a packed bed when diffusivity E and the velocity u are permitted to vary with radial position was solved by use of an I.B.M. card‐programmed calculator for the computations.

The results show that the Peclet number Dpu/E increases from the center towards the wall of the pipe and that the increase is significant when Dp/Dt is greater than 0.05. Empirical correlations are then presented for both point Peclet numbers, which vary with radial position, and average Peclet numbers for the entire bed.

The variations in Peclet number with radius can be explained in terms of the corresponding variation in void fraction for 81% of the radius of the bed. At modified Reynolds numbers above 40 to 100 the equation Pe = 8.0 + 100 (δ — δ0) correlates the effects of pipe and packing size and radial position. At radial positions greater than 0.81 wall friction influences turbulence conditions and the Peclet number.
Transport of momentum and energy in a ducted jet: II. Theoretical study of turbulent transport of momentum, energy, and matter in ducted coaxial streams
Authors: Alexander L. G. , Kivnick Arnold , Comings E. W. , Henze E. D.
Published: June 2004

This paper concerns the kinetics of the processes that take place when a high‐velocity jet of fluid mixes turbulently with a low‐velocity, induced stream of the same fluid in a duct of uniform diameter. Semi‐two‐dimensional solutions of the equations of transport involving two empirical coefficients were obtained by application of Reichardt's hypothesis and three assumptions: (a) a negligible fraction of the flow entity (energy, mass, or momentum) is lost at the wall and the presence of the boundary layer may be ignored, (b) the static pressure is uniform over a section of the duct, and (c) the turbulence pattern is similar to that in free jets except that the duct wall limits the growth of the scale of the turbulence. A mixing index, which is a measure of the degree to which the jet stream remains unmixed with the induced stream at any point, was defined and related to the geometry of the system and the flow parameters by means of the theoretical equation, and a method of evaluating the empirical coefficients for a typical case of momentum transport was described.
Upward cocurrent annular flow of air and water in smooth tubes
Authors: Calvert Seymour , Williams Brymer
Published: June 2004

Two‐phase fluid flow is distinguished from single‐phase flow in two respects: (1) the cross section for flow of either fluid is not defined by the conduit alone and (2) not only the extent but the manner of frictional energy exchange for each fluid depends on the individual rates of flow for both fluids. It was believed therefore that an empirical approach would not adequately describe the various situations encountered in two‐phase flow, and so study was undertaken to obtain some understanding of the mechanisms of the flow of liquid with a free surface and the momentum exchange between fluids at that surface. It resulted in the development of a method of predicting liquid holdup and pressure drop for flowing systems in which the liquid, lifted by the gas flowing as a central core, moves upward as an annular film along the pipe wall.

In order to clarify the relationship of annular flow to the entire range of vertical two‐phase flow modes, a discussion of vertical two‐phase flow is presented, followed by an analysis of the special case of vertical, upward, annular flow; a description of the experimental work; and a comparison of experimental data with predictions.
Surface tension and the principle of corresponding states
Authors: Brock James R. , Bird R. Byron
Published: June 2004

Experimental surface‐tension data for pure substances have been correlated successfully by the use of two recent modifications of the principle of corresponding states. The results are expressed in terms of simple analytical relations which allow one to calculate the surface‐tension curves either from the critical constants Pc, Vc, and Tc or from Pc, Tc, and the boiling point Tb and also provide a method for estimating critical properties from surface‐tension measurements. In addition, a method for estimating the surface tension of molten metals is suggested.
Turbulence in falling liquid films
Authors: Stirba Clifford , Hurt D. M.
Published: June 2004

On the basis of fluid dynamic and heat transfer studies on falling‐film towers by various investigators, it has been commonly accepted by most workers that the liquid flow is essentially streamline in nature for liquid‐film Reynolds numbers under 1,800 to 2,000; conseuquently it would be expected that the rate of physical gas absorption in such liquid films could be predicted directly from a knowledge of molecular diffusion rates.

Measurements of the absorption of pure gases in falling liquid films at low Reynolds numbers substantiated the findings of other investigators that the mass transfer rates were manyfold greater than could have been predicted if molecular diffusion were the only transfer process. Increased interfacial area due to rippling of the liquid films could not account for the large increase in mass transfer rates found, and experiments with the addition of a dye stream to the liquid at the freer interface indicated turbulence.

Dissolution rates of slightly soluble solids coated on the tube wall to liquid films were measured and showed that the liquid film was not in laminar flow even for Reynolds numbers as low as 300.

An explanation is proposed which resolves these apparently conflicting results between momentum and heat and mass transfer, based on the fact that mass transfer measurements provide a more sensitive test for the presence of turbulence than do momentum or heat transfer measurements.
Perforated‐Plate extraction‐column performance and wetting characteristics
Authors: Garner F. H. , Ellis S. R. M. , Hill J. W.
Published: June 2004

The type of surface of the perforated plate influences the performance of a perforated‐plate column. Pilot plant data on a 4‐in column for the system toluenediethylamine‐water at 20°C. show that when the water phase is dispersed and the direction of mass transfer is from the continuous toluene to the dispersed water phase polyethylene plates give a continuous stream of droplets and a higher efficiency, but that when the direction of mass transfer is from the dispersed water to the continuous toluene phase the metal plates give the higher efficiency.
Dehydration of hydrazine by azeotropic distillation
Authors: Wilson R. Q. , Mink W. H. , Munger H. P. , Clegg J. W.
Published: June 2004

A process was developed for dehydrating aqueous solutions of hydrazine by azeotropic distillation with aniline as an entrainer. The ternary system hydrazine‐water‐aniline, which contains the minimum‐boiling aniline‐water azeotrope and the maximum‐boiling hydrazine‐water azeotrope, was studied by fractionation analysis to determine the position of the ridge or distillation barrier in the vapor and liquid surface. The studies showed that the position and curvature of this ridge were favorable for the production, by rectification, of a solution richer in hydrazine than the azeotropic proportions. The process comprised three operations. Approximately 70% of the hydrazine charged to the system was dehydrated.

Entrainers that form binary minimum‐boiling azeotropes with both hydrazine and water are discussed. Ternary systems with these entrainers have saddlepoint azeotropes that boil intermediate with respect to the other invariant components in the system.
Liquid films in viscous flow
Authors: Jackson Melbourne L.
Published: June 2004

A trace of radioactive material dissolved in a liquid enables the thickness of a moving film to be determined by measurement of the radiation emitted. The method is rapid and accurate and an average thickness is obtained directly even though the surface of the film may be irregular. Six liquids, having viscosities ranging from 0.5 to 20 centipoises were observed in flow down the inner wall of a vertical tube. Liquids having viscosities of about 1 centipoise or less exhibit typical viscous behavior with respect to film thickness even when waves are present. Liquids having larger viscosities give values of the film thickness which are less than for true viscous flow. The departure from normal behavior increases with increasing viscosity and occurs only over the region where the liquid moves in wave flow. Surface tension is not a factor in either wave formation or wave flow.

The wave motion appears at flow rates well within the viscous region and occurs when the Froude number exceeds unity. Equations derived for the viscous flow of liquid films on the inner wall of a vertical tube would be required where tube diameter is small or liquid viscosity large. Ordinarily the less complex equations for flow down a flat plate may be used. A theory of flow in the viscous region with waves present is suggested.
Chemical factors in propellant ignition
Authors: Cook Melvin A. , Olson Ferron A.
Published: June 2004

A method of studying solid propellant ignition is described which utilizes detonating gas igniters. This article describes (1) conditions required for obtaining reproducible igniter systems and (2) results of application of the method to four well‐known rocket propellants in which various “chemical” and “thermal” effects were brought out by suitable variations in the initial pressure and composition of the detonating gas igniter. Successful application of the detonating‐gas‐igniter method requires the use of steady state detonation waves, i.e., waves in which the detonation head has attained a steady “size” and momentum. Experimental data are presented which show that detonation (following the initial predetonation buildup) must travel 40 to 50 cm. in a 1‐in. diam. steel tube before these steady state conditions are established in the systems studied.

Results of studies by the detonating gas ignition method show that, besides the important purely physical effects of temperature and pressure, free oxygen and solid carbon in the igniter system are very effective in lowering the threshold ignition pressure. Moreover, increasing oxygen in the igniter markedly lowers the ignition time lag (τp) for appearance of an observable flame although it increases the time lag (τi) for appearance of reaction sufficient to cause the first measurable ionization in the reaction zone (τp ≫ τi). Although true flame‐ignition time lags were observed to be of the order of several milliseconds, reaction of the propellant was observed to start within 1 msec. (possibly immediately) after collision of the detonation wave with the propellant.

The detonating gas method is shown to provide a reliable measure of the relative ignition sensitivities of various rocket propellants.
Estimation of ternary vapor‐liquid equilibrium
Authors: Severns W. H. , Sesonske Alexander , Perry R. H. , Pigford R. L.
Published: June 2004

Isothermal vapor‐liquid equilibrium measurements were made at 50°C. for the ternary systems acetone‐methanol‐chloroform, acetone‐methanol‐carbon tetrachloride, and acetone‐methanol‐methyl acetate, by means of an improved vapor‐recirculation type of apparatus. The complete range of concentrations was investigated, including six of the seven constituent binary systems. Chemical methods, supplemented by density and refractive‐index measurements, were used for analysis.

Results are presented in the form of activity coefficients γ as a function of various concentrations. Binary and ternary constants for the three‐suffix Margules equations were determined by plots of (log γ) / (1‐x)2 as a function of the mole fraction x. Such equations have been found to represent both the binary and the ternary data adequately except in the system containing both methanol and carbon tetrachloride. For these mixtures a simplified four‐suffix equation, including a single ternary constant, correlates binary and ternary equilibrium data.

The data indicate that reliable estimates of ternary equilibria can be based on the assumption that the ternary constant C* is zero for mixtures in which all deviations from Raoult's Law are positive. This is interpreted as indicating that the probability of existence of trimolecular aggregates, two‐ or three‐component, in ternary solutions is no greater than the average of probabilities of existence of trimolecular aggregates in the constituent binary systems.

Based on equations of the Margules type, a procedure is outlined for determining binary constants rapidly and for planning experiments whereby a ternary system may be completely investigated with the aid of very few measurements.

The composition changes that the accompany differential distillation of the three ternary mixtures are described qualitatively in terms of the shape of the vapor‐pressure‐composition surfaces.
Flow of non‐newtonian fluids—correlation of the laminar, transition, and turbulent‐flow regions
Authors: Metzner A. B. , Reed J. C.
Published: June 2004

All available data on flow of non‐Newtonians in pipes have been correlated on the conventional friction factor — Reynolds number plot for Newtonian fluids. This correlation, theoretically rigorous in the laminar flow region, was tested with data on 16 different non‐Newtonian materials covering the 2.1 × 109 range of Reynolds numbers from 6.3 × 10−5 to 1.3 × 105. Pipe diameters varied from 1/8 to 12 in. As the correlation does not depend on the type of fluid encountered, it may be used with Newtonian and non‐Newtonian fluids alike.

In spite of the great range of the available experimetnal data, further work is necessary in the transition and turbulent‐flow regions. No data at all were available on thixotropic, rheopectic, and dilatant fluids, and extension of the correlation to these materials should prove most illuminative from both theoretical and practical viewpoints.
Capacity factors in the performance of perforated‐plate columns
Authors: Hunt Charles D'Ancona , Hanson D. N. , Wilke C. R.
Published: June 2004

A study was made of factors affecting the vapor‐handling capacity of perforated‐plate liquid‐vapor contacting columns. Vapor‐phase pressure drop across plates, liquid entrainment upward from plate to plate, and plate stability were investigated as functions of operational and geometric column parameters.

Gas‐phase pressure drop across dry perforated plates was observed to follow functional relationships predicted from available information for single perforations. The presence of liquid on a plate increased the total pressure drop by the equivalent clear‐liquid head plus a small residue which is nearly constant for a given liquid.

Entrainment was observed to be a function of column gas velocity, independent of gas velocity in the perforations. Weight rate of entrainment was also found to be proportional to the gas density, independent of liquid density, and inversely proportional to the liquid‐surface tension. For a given system, entrainment was observed to be proportional to approximately the third power of the group, gas velocity divided by the distance between the liquid surface and the plate above.

The stability of perforated plates was observed to be adequate for many industrial and experimental applications, as also reported in recently published studies, but contrary to qualitative statements found in the earlier literature. Stability was found to increase with decreasing perforation diameter and decreasing total perforation area relative to column cross‐sectional area; to increase with greater gas density, liquid surface tension, and liquid wetting power; and to be virtually independent of liquid density and viscosity.

Operating limits of vapor and liquid throughput are shown for a typical application of perforated plates in liquid‐vapor contacting columns.
Heat transfer in cylinders with heat generation
Authors: Topper Leonard
Published: June 2004

The prediction of temperatures has been studied for a tubular flow reactor when heat is generated at a rate which is a linear function of the local temperature. Analytical solutions are presented both for the case where the wall is isothermal and for the case where the exterior surroundings are isothermal and the heat transfer coefficient between the tube wall and the surroundings is constant. This analysis should be helpful for estimating local temperatures and also for predicting the transient response to changes in one of the independent operating variables.
Kinetics of the methane‐steam reaction
Authors: Akers W. W. , Camp D. P.
Published: June 2004

A kinetic study was made of the reaction of steam and natural gas over a reduced nickel catalyst at a temperature range of 637° to 1,180°F.

The rate of reaction is first order with respect to methane. The effect of temperature could be expressed by an Arrhenius type of equation. Both carbon monoxide and carbon dioxide are formed as primary reaction products.
Graphical solutions on dimensionless‐number plots
Authors: Fitch Bryant
Published: June 2004

A graphical method for solving problems involving dimensionless‐number plots is presented, and its application demonstrated for the relatively involved case of liquid cyclone scale‐up.
Activity coefficients at infinite dilution
Authors: Gautreaux M. F. , Coates Jesse
Published: June 2004

Equations are derived for obtaining activity coefficients at infinite dilution in binary systems by use of one of the following: (1) an isobaric temperature—liquid composition diagram, (2) an isobaric temperature—vapor composition diagram, (3) an isothermal pressure—liquid composition diagram, or (4) an isothermal pressure—vapor composition diagram. The derived equations are thermodynamically exact, and application involves no doubtful extrapolation of experimental data, as has heretofore been the case.

Each equation involves the slope of one of the diagrams at the point corresponding to the pure component. Attention is called to the fact that data on the compositions of both the vapor and liquid phases in equilibrium are not required. Use of the equations is illustrated.
Pipe‐line design for non‐newtonian fluids in streamline flow
Authors: Christiansen E. B. , Ryan N. W. , Stevens W. E.
Published: June 2004

A method is presented for determining the flow‐rate—pressure‐gradient relationship for the streamline flow of the large class of non‐Newtonian, nonthixotropic fluids to which the Powell‐Eyring equation applies. The general procedure and assumptions required in developing this method are the same as used in deriving the Hagen‐Poiseuille equation except that the Powell‐Eyring equation is used in place of Newton's equation to relate shear stress to shear rate.

The method can be used to predict pipe‐flow pressure gradients from both precision viscometer data and pipe‐flow data. Its applicability is demonstrated for three typical non‐Newtonian fluids, 3% carboxymethylcellulose in water, 15% napalm in kerosene, and 33% hydrated lime in water.

When used with pipe‐flow data, it resembles the method of Alves and associates, compensating for the inconvenience of an additional step in calculation procedure by providing a means of extrapolating beyond the range of the experimental data.

The relationships developed facilitate the application of shear‐stress—shear‐rate data in the design of conduits for non‐Newtonian fluids.
Entrainment removal by a wire‐mesh separator
Authors: Carpenter C. LeRoy , Othmer Donald F.
Published: June 2004

The efficiency of a wire‐mesh separator as an entrainment eliminator has been experimentally determined in an evaporator employing a sodium chloride brine to trace the entrainment throughout the system. Superficial linear velocities have been tested with efficiencies ranging from less than 80% at lower velocities up to 99.9% at 17 ft./sec. Higher superficial linear velocities were explored, but the results were erratic, with reentrainment from the separator visually evident. The experimental data have been correlated by the assumption, and development, of a proposed mechanism for the capture of the entrainment particles by the wires in the separator. This mechanism is developed from a theoretical derivation by Langmuir and Blodgett used for correlating the stoppage of mist particles by the leading edges of airplanes and has been found to correlate the experimental data very well, so that predictions in unworked ranges may be made. The separator as applied in this experimental work behaved as an impingement‐type, inertial entrainment eliminator.

The use of the presently developed equations permits the recommendation of specifications to be used in the fabrication of a separator for its most efficient performance if the nature of the entrainment and conditions of operation are known.
Regenaration of fluidized cracking catalysts
Authors: Pansing William F.
Published: June 2004

An equation for correlating regeneration process variables in fluid‐catalytic cracking has been developed from pilot plant data. This equation takes into account not only the chemical‐reaction rate for burning coke deposited on the catalyst but also the diffusional resistance to oxygen transfer. The resistance presumably occurs between the bubbles within the fluidized bed and the void spaces in the relatively denser mass of particles. The coefficient of mass transfer was found to be inversely proportional to the 1.5 power of the average particle diameter and directly proportional to the square of the gas mass velocity. The specific reaction‐verlocity constant was found to be a function to temperature and catalyst activity as well as the nature of the feed from which the coke was deposited. Comparison of pilot plant data with commercial data suggests that nonuniform gas distribution in larger beds makes some of the catalyst ineffective.
Performance of an internally baffled multistage extraction column
Authors: Scheibel Edward G.
Published: June 2004

Internally agitated extraction columns generally require increasing heights for a theoretical state for the larger column diameters. The present work describes a design developed to minimize this objection and presents the performance data on a system considered easy to extract and on systems considered difficult to extract. H.E.T.S. values as low as 3 in. on the first system and 4 in. on the second type of system were obtained in an 11½ in I.D. glass column. The stage efficiencies were correlated as a function of power input per unit volume of solvent throughput and the ratio of the flow rate of the dispersed phase to that of the continous phases. The supplementary effect of packing was studied and found to be most beneficial in the system which has a low interfacial tension and is considered easy to extract. By the use of this particular arrangement of internal baffles, it is believed possible, in the larger diameter columns, to reduce the height to a ratio of H.E.T.S. to diameter below the value of ¼ obtained in the present column.
Prediction of specific heat of organic liquids
Authors: Sakiadis Byron C. , Coates Jesse
Published: June 2004

A theoretical equation is presented for predicting the specific heat at constant volume and constant pressure of organic liquids as a function of temperature from data on the velocity of sound, infrared and Raman spectra. By use of this equation, the average deviation of the calculated from the experimental values of specific heat for 100 organic liquids at 68°F. is ±1.5%.

An alternate correlation for hydrocarbon liquids based on a modified statement of the theory of corresponding states is also presented. Based on it, the average deviation of the calculated from the experimental values for 100 points representing the entire temperature range is ±0.9%.
Chemical reactor stability and sensitivity: II. Effect of parameters on sensitivity of empty tubular reactors
Authors: Bilous Olegh , Amundson Neal R.
Published: June 2004

In this paper extensive calculations on the quasi isothermal tubular reactor are presented. Temperature and concentration profiles were obtained on an analogue computer (R.E.A.C.). The calculations tend to show that there are regions of operation in which the reactor effluent is very sensitive to operating conditions. For example, it is shown that in some regions of operation a small change in the heat transfer coefficient at the reactor wall or a small dilution of the feed will produce large changes in the effluent. In such cases the reactor is said to exhibit parametric sensitivity. It is shown analytically that this sensitivity may be predicted by analyzing the frequency response or transient response of the reactor approximated by a local linearization. This linearization requires complete solutions of the steady state problem. Semiquantitative results are then obtained for the regulation required from a given specification of product limits. The frequency‐response analysis should be useful in connection with the control problem.

If the reactor is fed partially with a recycle stream, then experience with electrical systems indicates that the possibility of instability exists. It is shown that at least theoretically these instabilities do exist, and a method based on the transfer function is developed for derivation of criteria of stability or instability.
Flooding characteristics of a pulse extraction column
Authors: Edwards R. B. , Beyer G. H.
Published: June 2004

An investigation using the hexone‐water system was made of flooding in a 1‐in.‐diam. ten‐plate pulse column. An analysis of column operation led to the derivation of an equation for predicting conditions of inadequate pulsation and for establishing the amount of liquid recycled under any operating conditions.
Estimation of heat sources in nuclear reactors
Authors: Alexander Lloyd G.
Published: June 2004

Knowledge of local heating rates is needed for estimation of operating temperatures, thermal stresses, and cooling requirements in nuclear reactor components. Heat is liberated by the dissipation of the energy of fission fragments, beta particles, fast neutrons, and gamma photons. Heating rates are formulated in terms of either neutron or gamma flux densities, the corresponding collision probabilities, and appropriate energy transfer coefficients, the forms of which are given. Special methods of estimating the flux densities are discussed. The data on the magnitudes of the various energy sources are reviewed.
Neutron lifetimes and void coefficients for research reactors
Authors: Pigford Thomas H. , Troost Marius , Powell James R. , Benedict Manson
Published: June 2004

Prompt neutron lifetimes and viod coefficients were calculated for research reactors using M.T.R.‐type fuel elements, moderators of light and heavy water, and reflectors of light water, heavy water, graphite, and beryllium. Heavy‐water‐reflected and ‐moderated research reactors may have neutron lifetimes of the order of 0.001 sec. as compared with about 0.00006 sec. for a light‐water‐reflected and ‐moderated research reactor. Lifetime of the light‐water core can be improved considerably by use of better reflectors, but at a substantial reduction and even reversal in sign of the void coefficient.
Plate efficiency with chemical reaction—absorption of Carbon dioxide in Monoethanolamine solutions
Authors: Kohl Arthur L.
Published: June 2004

The effect of chemical reaction on plate efficiency has been given little attention in the determination of bubble‐plate efficiencies, although it is of importance in many operations. A typical example is the absorption of carbon dioxide in monoetnanolamine solutions.

The over‐all Murphree gas‐phase plate efficiency can be shown to be a function of Kg(A/V) where A/V is the interfacial surface area formed per tray per unit volume of gas. In order to evaluate variations in tray efficiency due to factors influencing Kg, data available in the literature for the absorption of carbon dioxide in monoethanolamine were considered. These showed that the liquid film was controlling and that for a packed column at constant liquid rate the absorption coefficient could be satisfactorily expressed by an equation that resembles somewhat equations which have been developed for the effect of rapid secondorder reactions on kL. However, the observed effect of carbon dioxide partial pressure in the gas is not so great as the theoretical equations would predict.

By use of the equation mentioned above to predict Kg, satisfactory correlation of observed plate efficiencies is obtained for a commercial column over a considerable range of conditions. It appears that the correlation can be extended to other pressures, flow rates, and column designs by an evaluation of the effect of these variables on A/V and Kg.
Diffusion coefficients in hydrocarbon systems: n‐heptane in the gas phase of the ethane–n‐heptane and propane–n‐heptane systems
Authors: Carmichael L. T. , Sage B. H.
Published: June 2004

Because little information is available concerning the behavior of hydrocabons under conditions far from equilibrium, it appears desirable to obtain data for the diffusion coefficients of the lighter hydrocarbons in the gas phase.

The Maxwell diffusion coefficients of n‐heptane in the gas phase of the ethane‐n‐heptane and propane‐n‐heptane systems were measured at temperatures from 100° to 220° F. and for pressures up to 60 lb./sq. in. The fick diffusion coefficient was calculated as a function of state from these measurements.

The experimental results indicate that the interfacial resistance between the liquid and the gas phases into which the transport was taking place is small. It was found that pressure exerted a significant influence upon the Maxwell diffusion coefficient for both of the binary systems investigated. There is a marked decrease in the Maxwell diffusion coefficient with an increase in molecular weight of the stagnant component.
Viscosity of liquids
Authors: Albright Lyle F. , Lohrenz John
Published: June 2004

Three viscosity correlations were tested for liquids at their boiling points. Compounds studied included normal paraffins, branched‐chain hydrocarbons, aromatics, halogenated methanes and ethanes, water, and aliphatic alcohols. The correlations were tested for the most part with viscosity and thermodynamic data found in the literature. Some experimental viscosity measurements were made, however, for normal paraffins from pentane to octane at temperatures up to about 300°F., which is higher than has previously been reported.

Two correlations are based on Eyring's theory of absolute reaction rates. The third is based on the compressibility factor of the saturated liquid, and this correlation is unique, as all available data for normal paraffins with eight or more carbon atoms are represented by a single curve. The three correlations presented here can be used to extrapolate viscosity data over large temperature ranges up to the critical temperature. Logical predictions of the viscosities of related compounds are possible.
Structure and performance of filter media. II. Performance of filter media in liquid service
Authors: Grace H. P.
Published: June 2004

The performance of nine typical filter media of previously determined pore structure has been determined by the filtration of very dilute suspensious containing spherical particles of known size distribution. The mechanisms of filtration prior to the formation of a macroscopic cake are considered, and the applicability of various filtration laws proposed by Hermans and Bredée to describe these regious of filtration are examined. Regions of “standard‐blocking” filtration are found to occur with each of the filter media examined. The clogging values for the various media over the region of standard blocking are shown to be related quantitatively to the modal value of interfiber pore radius of the media, as measured by the mercury‐intrusion method.
Formation of gas bubbles at horizontal orifices
Authors: Davidson Leon , Amick Erwin H.
Published: June 2004

Air bubbles were formed in water and in mineral oil by use of single, circular, horizontal, square‐edged orifices facing upward. Twenty orifices were tested, ranging from 0.017 to 0.79 cm. (0.0067 to 0.31 in.) in radius. Incieasms the whime, of the gas chamber below the orifice (over the range of 4 to 4,000 cc.) was found to increase the bubble size. The gas‐chamber volume was minimized in most of the work in order to confine attention to the effects of orifice size and gas‐flow rate. The liquid containers were large enough to eliminate significant wall effects, and operations were conducted at atmospheric pressure.

The gas‐flow rate was varised from about 0.01 to about 250 cc./sec. over the course of the work. At relatively low rates, the orifices generally formed single “static” bubbles, the volumes of which were proportional to the surface tension and orifice radius and independent of the gas‐flow rate. At high flow rates the bubble frequency became high and the bubble volume became proportional to the gas‐flow rate and independent of the surface tension. The bubble frequency reached a maximum value for each orifice, this value being a function of the orifice radius. For air bubbles in water, the correlation of the maximum bubble frequency, nm bubbles/sec., with the orifice radius, r cm., and the air‐flow rate, q cc./sec., was found to be nm = 9.1q0.13/r0.43. The maximum frequencies ranged from about 25 bubbles/sec. for the largest orifices to about 75 bubbles/sec. for the smallest orifices used.

It was found that consecutive bubbles paired or coalesced in definite ways in certain ranges of the gas‐flow rate. A description is given of this bubble behavior, based on stroboscopic and photographic observation.
Enthalpy of hydrocarbon mixtures
Authors: Canjar Lawrence N. , Peterka Vernon J.
Published: June 2004

A method of estimating enthalpies of mixtures of light hydrocarbons is presented. Enthalpes so obtained are consistent with equilibrium‐vaporization constants that have been correlated with the composition characterization factor, the molal average boiling point (M.A.B.P.).

Values of the isothermal‐pressure corrections to the enthalpy of ideal gas mixtures (H°  H) are presented on three plots with parameters of temperature, pressure, and molal‐average boiling point. Pressures range from zero to 1,500 lb./sq. in. abs., temperatures from −200° to 500°F., and M.A.B.P. from −200° to 150°F.
Theorem of corresponding states applied to saturated liquids and vapors
Authors: Hobson Merk , Weber James H.
Published: June 2004

The existence of a single generalized compressibility‐factor relationship for univariant systems has long been denied because reduced variables do not provide a generalized vapor‐pressure relationship. The present study demonstrates that a saturation curve depends on the ability of the theorem of corresponding states to correlate the reduced temperature as a function of reduced, pressure and the critical compressibility factor. Saturation curves for both the liquid and the vapor phases are established from compressibility data on a variety of systems, substantiating this conclusion.

The compressibility factors of saturated mixtures are correlated with pseudoreduced properties based upon Kay's pseudocritical concept. The results indicate that the compressibility factors of saturated liquid mixtures can be predicted with reasonable precision over the entire two‐phase region. For pseudoreduced isotherms of unity and above, the same isotherms apply to both phases and are approximately consistent with published compressibility charts for pure gases.
Turbulent exchange of mass and momentum with a boundary
Authors: Hanratty Thomas J.
Published: June 2004

Visual observations by Fage and Townend of the behavior of a turbulent‐flow strean near a boundary and experimental data by Lin, Moulton, and Putnam of concentratiol profiles near a boundary contradict the commonly held concept of the “laminar sublayer.” A model developed by Higbie and Danckwerts which is consistent with the visual obser vations of Page and Townend is used to describe the exchange of mass and heat between a turbulent fluid and a solid surface. It is postulated that masses of fluid are contiuously moving to and from the wall. The exchange process then depends on the average contact time of these fluid masses with the wall.

The agreement of the concentration profile predicted on the basis of the proposed model with experimental mass transfer data where the exchange process is rate controlling lends support to the usefulness of the model. No equivalent data are available for velocity profiles. Velocity data represent a condition where the transport process within the fluid is playing an important role; however, in the immediate vicinity of the wall the proposed model might serve as a rough approximation of the profile. Such an approximation is made in this paper, and the agreement obtained is much better than should be expected.
Turbulent diffusion in particulately fluidized beds of particles
Authors: Hanratty Thomas J. , Latinen George , Wilhelm Richard H.
Published: June 2004

Measuring the spreading of a tracer dye from a point source yields information on diffusion in glass‐sphere beds fluidized in water. Particulately fluidized beds, which are here formed, are well described by the statistical turbulence equations of Taylor. Mixing parameters—eddy diffusivity, scale, and intensity of turbulence—are established. Transition of these variables is traced from fixed beds through fluidized beds in different degrees of bed expansion.

Mixing characteristics of these “ideal” types of fluidization may provide a frame of reference for consideration of more complex systems.
Differential heats of condensation and enthalpies of saturated liquid hydrocarbon mixtures
Authors: Stiehl J. G. , Hobson Merk , Weber James H.
Published: June 2004

By use of saturated‐vapor enthalpies determined by accepted procedures in conjunction with differential latent heats of condensation, the saturated‐liquid enthalpies are established for the system methane–ethane at 200, 400, and 600 lb./sq. in. abs. and for the system ethane–n‐butane and propane–n‐butane at the two lower pressures. Where comparison is possible, the liquid‐enthalpy values obtained by this method are in general agreement with those previously determined by Edmister and Canjar. The procedure used is thermodynamically rigorous and may be applied to any binary mixture, provided the Benedict‐Rubin‐Webb equation of state is valid in the vapor phase and P‐V‐T‐x data are available.
Mass transfer studies in an agitated vessel
Authors: Johnson A. I. , Huang Chen‐Jung
Published: June 2004

A study of rates of dissolution of organic solid from a flat surface into turbulent liquid in a mixing tank of 6 in. I.D. is reported for five systems—benzoic acid–n‐water, salicylic acid–water, salicylic acid–benzene, succinic acid–n‐butanol, and succinic acid–acetone. Previous theories for the rates of mass transfer are reviewed and compared, and experimental results analyzed and correlated by an equation in terms of dimensionless groups similar to that of Hixson and Baum, Sherwood and Gilliland, and Rushton and Oldshue. The close agreement between the theoretical and experimental values of the exponent of the Schmidt number in this equation may provide new and significant evidence for the applicability of the surface‐renewal theory to mass transfer from a flat solid surface into a turbulent liquid.

For free rotational agitation, a local mass transfer coefficient with respect to the position of a cast solid was detected quantitatively. However, the insertion of four baffles into the tank gave a uniform mass transfer coefficient regardless of the position of the cast solid. A decrease in the mass transfer coefficient was observed when baffles were used.

The advantages of the constant and stationary interface, the stability and simplicity of the apparatus, the possibility of duplicating experimental results, and the success of the detection of a local mass transfer coefficient suggest that the present apparatus and procedures could be used for the study of the theory of mass transfer rates from flat surfaces.
The chemical equilibrium of the Ammonia synthesis reaction at high temperatures and extreme pressures
Authors: Winchester Leonard J. , Dodge Barnett F.
Published: June 2004

Chemical equilibrium in this reaction has been determined experimentally by a static or nonflow method at temperatures of 400° and 450°C. and at pressures of 1,000 to 3,500 atm. Equilibrium was approached from both sides and the two reacting gases were always in the stoichiometric ratio. The results are presented both as mole percentage of ammonia in the equilibrium mixture and as the equilibrium constant Kp. The constant, Kp, which is a function of pressure, was calculated from Kp°, its value at p = 0, by five different methods and from them the corresponding mole percentages of ammonia were derived for comparison with the experimental results. All such calculations involve assumptions of varying degrees of validity, and no calculated value can be considered accurate. However two of the calculation methods give values which agree reasonably well with the experimental values.
Critical constants of the naphthenic hydrocarbons
Authors: Thodos George
Published: June 2004

Group‐contribution values are presented and, together with those already developed for the aliphatic hydrocarbons (10, 11), make possible the evaluation of both van der Waals' constants for the naphthenic hydrocarbons. These constants can be used to produce the critical temperatures, pressures, and volumes of these compounds entirely from a knowledge of their chemical structure.

Critical constants have been calculated for several naphthenes, and from a comparison of them with the constants resulting from the methods of Riedel (5, 6) and Lydersen (3) it was found that the critical constants calculated by these three methods were in fair agreement for naphthenes having short alkyl side chains and progressively deviated from each other as the chains were permitted to lengthen. An appraisal has been made on five naphthenes along the lines proposed by Sondak and Thodos (9) in order to see whether these calculated critical constants properly represent the vapor‐pressure function resulting from vapor‐pressure data found in the literature for these hydrocarbons.

Critical constants have been produced for more than fifty naphthenes, for which vapor‐pressure data are available in the literature, and will be used in a separate, comprehensive vapor‐pressure study for hydrocarbons of this type.
Thermodynamic properties of n‐hexane
Authors: Weber James H.
Published: June 2004

Thermodynamic properties of n‐hexane have been calculated over a temperature range of 32° to 540°F. and up to a pressure of 600 lb./sq. in. abs. These properties were determined from vapor pressure, volumetric, heat capacity, and latent heat of vaporization data through the application of rigorous thermodynamic relationships. The calculated data have been found to be internally consistent. The enthalpy values are believed to be accurate to within 0.5 B.t.u./lb. and the entropy values to 0.0005 B.t.u./(lb.)(°R.).