bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axial dispersion of spheres fluidized with liquids
Authors: Kennedy S. C. , Bretton R. H. 
Published: June 2004

AbstractSolids dispersion due to the simultaneous diffusion (random particle motion) and classification (segregation) of fluidized spheres has been investigated. The model developed permits calculation of the mean concentration of spheres of both sizes in a mixture of two sizes of fluidized spheres as a function of bed length. Fick's law has been applied to the diffusional phenomenon. A hypothesis has been advanced and confirmed which permits calculation [Equation (5)] of the classification velocity for each size of sphere in a fluidized mixture. Calculation of the classification velocities in a mixture of spheres is based on the relation of void fraction to superficial velocity for the individual sizes of spheres. To facilitate carrying out these calculations, a generalized equation has been developed for the relation of void fraction to superficial velocity in terms of the Galileo number (d3gΔρρƒ/μ2) and sphere‐to‐column diameter ratio. Measurement of the bead size gradients (change in bead size with bed length) at steady state fluidization was used to investigate dispersion. Closely sized glass beads of 0.1 and 0.2 cm. diameters were fluidized with liquids of 1 and 15 cps. at void fractions of 0.5 to 0.8 in 2.5 and 5.0 cm. columns. Lead beads of 0.12 cm. diameter were also used. Further, several experiments were conducted by a method which is analogous to that used in molecular diffusion cells.
The low temperature removal of small quantities of nitrogen or methane from hydrogen gas by physical adsorption on a synthetic zeolite
Authors: Kidnay Arthur J. , Hiza Michael J. 
Published: June 2004

AbstractA flow system was used to measure the physical adsorption isotherms of two mixtures of nitrogen and hydrogen and two mixtures of methane and hydrogen on a synthetic zeolite. The measurements were made at liquid nitrogen temperature and at pressures of 4 to 85 atm. Static systems were used to measure the pure component isotherms of nitrogen, methane, and hydrogen at the same temperature and over the appropriate pressure ranges.Although many different methods have been proposed for using pure component adsorption isotherms to predict the mixture isotherm, the only method giving quantitative agreement with the data of this study is the empirical “adsorption enhancement factor” (4).In addition to the adsorption isotherms, the concentration‐time or breakthrough curves of the mixtures were measured at flow rates ranging from 40 to 300 lb./(hr.)(sq.ft.). The method proposed by Eagleton and Bliss (18) was used to correlate these curves.
Laminar converging flow of dilute polymer solutions in conical sections: Part I. Viscosity data, new viscosity model, tube flow solution
Authors: Sutterby J. L. 
Published: June 2004

AbstractThis investigation is reported in two parts. Necessary background information is introduced in Part I. The converging flow investigation proper is described in Part II (18).In Part I, viscosity data are presented for polymer solutions used in the converging flow experiment. These data are fitted with a new three‐parameter viscosity model which fits the data better than previous three‐parameter models. (The viscosity model parameters are used in Part II to characterize rheological behavior of the polymer solutions in the converging flow experiment.) The corresponding relationship between flow rate and pressure drop for laminar flow in cylindrical tubes is derived. (In Part II this relationship is used in deriving an analogous relationship for slow non‐Newtonian flow in conical sections.)The primary purpose of Part I is to provide background information for Part II. However, the new viscosity model and the tube flow relationship are of some interest in themselves. The new viscosity model should prove useful for describing viscosity data of a variety of polymer solutions and polymer melts. A simple procedure for fitting the model to viscosity data is described. The tube flow relationship can be used for predicting pressure losses once the viscosity model parameters have been determined. Conversely, it can be used for determining the viscosity model parameters from tube flow data.
Characterization and gain identification of time varying flow processes
Authors: Mellichamp D. A. , Coughanowr D. R. , Koppel L. B. 
Published: June 2004

AbstractA method for continuously estimating the gain of a flow process by sinusoidal perturbation is presented. The resulting output perturbation is correlated with a second sinusoid to generate periodically an estimate of the process gain. A method of implementing such an identifier on a small analog computer is described.The experimental testing of this identifier computer with both a real process (a pH regulating system) and with an analog computer simulation of the process is described. The results of identification tests with a nonstationary system are presented. From these results it is concluded that the identifier estimates the process gain satisfactorily, introducing a delay (equal to one‐half the period of identification) and making an effective sampling or clamping of the gain estimate (over each period of identification).
The influence of diffusivity on liquid phase mass transfer to the free interface in a stirred vessel
Authors: Kozinski Allen A. , King C. Judson 
Published: June 2004

AbstractLiquid phase mass transfer coefficients were measured in a continuous flow, stirred vessel containing a gas and a liquid phase. Helium, hydrogen, oxygen, argon, and carbon dioxide were desorbed from distilled water into nitrogen at seven different levels of agitation. At low stirring speeds the system was stratified and mass transfer coefficients were proportional to diffusivity raised to a power between 0.5 and 0.6. At higher stirring speeds the interface was broken and corrections for desorption into the entrained bubbles indicated that the mass transfer coefficient at the main free interface was proportional to a higher power of diffusivity. The results are interpreted in the light of a general model considering eddy diffusion and surface renewal effects.
Mass transfer in a horizontal rotating cylinder with applications to the oxygenation of blood
Authors: Landino Enrique , McCreary J. G. , Thompson W. A. , Powers J. E. 
Published: June 2004

AbstractThe horizontal rotating cylinder blood oxygenator has been developed to minimize shear, eliminate bubbles, reduce holdup, and provide for rapid change of the controlled temperature of the blood.To aid in the development of this apparatus a detailed mathematical model was formulated. A simplified model was also developed which yielded an analytical expression relating the amount of material transferred between the gas and liquid in the apparatus to operating variables. In developing these models an attempt was made to include a realistic mechanism for oxygen absorption in blood.Preliminary experiments were carried out by absorbing carbon dioxide into distilled water in the horizontal rotating cylinder. These preliminary results were found to be in good agreement with previous theoretical predictions and calculations that indicated that the equipment should be adequate to act as a lung substitute for a dog. When it was employed in this manner during open‐heart surgery, insufficient oxygen was transferred to support the dog.It is concluded that the most probable reason for failure of the horizontal cylinder to act satisfactorily as a blood oxygenator is poor mixing in the blood pool.
The time‐optimal control of discrete‐time linear systems with bounded controls
Authors: Lesser Herbert A. , Lapidus Leon 
Published: June 2004

AbstractThe discrete‐time, time‐optimal control of high‐order, linear systems with bounded controls is formulated as a problem in linear programming. The solution obtained requires a certain minimum number of controls to be on their bounds. Numerical results are obtained for a system with controls bounded on one and both sides and extensions indicated for state variable constraints. The method proves to be extremely fast and simple to solve on a high‐speed digital computer.
Formation of interfacial area at high rates of gas flow through submerged orifices
Authors: Abdel‐Aal H. K. , Stiles G. B. , Holland C. D. 
Published: June 2004

AbstractInterfacial area was formed by passing air through orifices that were submerged horizontally beneath 4.5 ft. of each of four different liquids. The flow rates of the air ranged from 0.095 to 1.34 (st. cu. ft./min.), the diameters of the orifices ranged from 0.03125 to 0.1875 in., and the I.D. of the orifice holders ranged from 1 to 2.5 in.The areas were measured with a photocell, a recorder, and an integrator. This combination gave the time average of the interfacial area that passed a selected plane of the column.The interfacial area produced was correlated as a function of the physical properties of the fluids, the diameter and number of orifices per plate, and the gas flow rate.
Heat transfer to non‐Newtonian fluids in transitional and turbulent flow
Authors: Petersen A. W. , Christiansen E. B. 
Published: June 2004

AbstractTurbulent and transitional flow heat transfer correlations for non‐Newtonian fluids are presented. By means of an extension of the Reichardt‐Metzner‐Friend correlation to nonisothermal flow, and a new definition of Prandtl number to account for deviations from Newtonian behavior, turbulent flow data are correlated to a standard deviation of 14.8%. By means of a normalizing procedure, data for the complex case of transitional flow heat transfer to non‐Newtonian fluids are correlated to a standard deviation of 17.7%. At the transition region boundaries, the correlation is consistent with laminar and turbulent flow correlations. A basic similarity in the Newtonian and non‐Newtonian heat transfer mechanisms is suggested.
Free and forced convection in conduits with asymmetric mass transfer
Authors: Gill William N. , Casal Eduardo Del , Zeh Dale W. 
Published: June 2004

AbstractApproximate solutions for the thermal entrance region and a new exact solution for the fully developed region have been obtained for nonlinear fully developed conduit flows with unsymmetrical transverse flow. Entrance region solutions are obtained by a generalized version of Mercer's method. The effects on combined free and forced convection of asymmetric mass transfer, in the asymptotic region of fully developed thermal and hydrodynamic conditions, are studied and a new exact solution is given which applies to such problems.
A theory of withdrawal of cylinders from liquid baths
Authors: White David A. , Tallmadge John A. 
Published: June 2004

AbstractA theory of the amount of liquid entrained by cylinders upon withdrawal from liquid baths is derived for a wide range of cylinder radii. The theory is based on matching curvatures for static and dynamic menisci. Predicted values are expressed as the effect of the dimensionless wire radius (Goucher number) and dimensionless withdrawal speed (capillary number) on the dimensionless flux.The theory was verified experimentally for all wire radii by removing short cylinders from oily fluids and with other information. The fluids used included kerosene, mineral oil, motor oil, and glycerine, with viscosities from 2 to 500 centipoise; Goucher numbers ranged from 0.05 to 1.2. Deviations, which were noted at high capillary numbers where velocity gradients become appreciable, indicated that the theory is a plug flow or low speed theory. Also discussed are differences found with water and the conditions under which films coalesced into droplets.
Bubble shapes in nucleate boiling
Authors: Johnson M. A. , De La Peña Javier , Mesler R. B. 
Published: June 2004

AbstractAn attempt is made to explain the differently shaped bubbles observed growing on a surface during nucleate boiling of water. Some of the bubbles photographed were very close to the spherical shape, while others were close to the hemispherical. Also, a number of bubbles had intermediate shapes and were called oblate bubbles.Measurements of bubble dimensions and growth rates obtained from high‐speed films were analyzed. By using a modified Rayleigh equation, the relative importance of the inertial and surface tension forces was computed. it appeared that the differences in shapes among bubbles can be explained on the basis of the relative importance of these forces.It was found that for spherical bubbles inertial forces are small because of the slow growth rate and surface tension is clearly the dominant force. For hemispherical bubbles, however, the fast growth rate causes a very large inertial force which is greater than surface tension. For the oblate bubbles neither of the forces was found to be dominate and inertia as well as surface tension determines the shape.
Application of the Gibbs‐Konovalow equations to binary phase equilibria
Authors: Franzen H. F. , Gerstein B. C. 
Published: June 2004

AbstractThe Gibbs‐Konovalow relations are shown to provide a unified approach to the description of binary two‐phase equilibria. The relations are applied to a consideration of high order transitions (7) and are shown to easily lead to well‐known, but generally uncorrelated, hehavior of slopes of lines separating two single‐phase regions in binary systems. In particular, the conditions under which the slope of the temperature‐composition line is zero, constant, or undefined in the neighborhood of congruent and peritecticThe meanings of these terms will be amplified in the text
processes are derived.
The P‐V‐X behavior of the liquid system acetone‐carbon disulfide at elevated pressures
Authors: Winnick Jack , Powers J. E. 
Published: June 2004

AbstractThe change in volume on mixing for a system showing large positive deviations from ideality is examined at one temperature to pressures of 100,000 lb./sq.in. Original atmospheric pressure density data and compression measurements over the entire mole fraction range for this system, acetone–carbon disulfide, are reported at 0°C. These are correlated with the semiempirical Tait equation to yield change in volume on mixing as a function of mole fraction and pressure.This volume change is found to decrease from the maximum of 1 cc./mole at atmospheric pressure to about 0.4 cc./mole at 100,000 lb./sq.in. The maximum also shifts during this pressure increase from 0.53 mole fraction acetone to 0.74.
Liquid‐liquid phase behavior of binary solutions at elevated pressures
Authors: Winnick Jack , Powers J. E. 
Published: June 2004

AbstractIsothermal pressure elevation can sometimes cause liquid‐liquid phase separation of binary liquid mixtures. A quantitative thermodynamic analysis of this effect is made and applied to the system acetone–carbon disulfide at 0°C. with the use of available P‐V‐T‐X data and vapor pressure data at low pressure. Visual observations of the phase separations at pressures up to 80,000 lb./sq.in. were used to compare with the results of the thermodynamic analysis.
An equation of state for gas mixtures
Authors: Othmer Donald F. , Chen Hung Tsung 
Published: June 2004

AbstractA pressure‐volume‐temperature equation for mixtures of two or more gases has been developed using the “reference substance” technique of comparing the properties of one substance with those of a standard under the same conditions.The compressibility factor is a function of temperature and pressure, with the variation from one substance to another being determined by the forces of attraction and repulsion between molecules. Thus, if the Lennard‐Jones 6‐12 potential function is used to describe the molecular interaction, the change in the compressiblity function reflects the different force constants, which in turn are functions of the critical constants.A mixture of gases is assumed to have the same thermodynamic properties as some hypothetical or pseudo gas which would have the same force constants existing between each pair of molecules in the mixture. The force constants of the pseudo gas may be evaluated from pseudo critical constants, which may be evaluated from the critical constants of individual components of the mixture.With the resultant force constants, there can be calculated the ratio of the compressibility factors of the gas mixture to those of a pure gas, nitrogen, taken as a reference substance, all values taken at the same reduced temperature and pressure. The compressibility factor of the mixture may be calculated from this ratio and the compressibility factor of the reference substance; and the PVT relations are immediately determinable.A comprehensive survey of the literature for PVT data of gas mixtures was made. More than 1,000 experimental values of PVT data for thirty‐four binary systems and four ternary systems have been studied. The proposed method showed an average deviation from experimental data, representing all published work, of 2.3%.
Computational studies of transients in packed tubular chemical reactors
Authors: Crider J. E. , Foss A. S. 
Published: June 2004

AbstractConcentration and temperature transients in a packed‐bed tubular chemical reactor were calculated from mathematical models in order to detemine the effects upon the reactor dynamics of several phenomena. The phenomena studied are the thermal capacity of the packing, the resistance to heat flow between the packing and the fluid, the coupling of temperature and concentration through the rate of chemical reaction, axial fluid mixing, radial fluid mixing, and the loss of heat at the wall. Three mathematical models were used: a two‐dimensional finite‐stage model, a one‐dimensional finite‐stage model, and a one‐dimensional first‐order differential model. The chemical reaction considered in these models was an exothermic, homogeneous, liquid phase, second‐order reaction.Machine calculations of transients following step changes in feed temperature or concentration showed that only the first three phenomena were important. It was also found that concentration transients in some cases initially moved in the direction leading away from the final steady state or overshot the final steady state. Further, a concentration node point was found to exist in the reactor under some circumstances. The one‐dimensional models considered were shown to be simple but quantitatively and conceptually useful.
The influence of axial dispersion on carbon dioxide absorption tower performance
Authors: Brittan Michael I. , Woodburn Edward T. 
Published: June 2004

AbstractCarbon dioxide was absorbed from mixtures with nitrogen by countercurrent contact with water in an experimental packed tower. Radial and axial gas concentration profiles were determined from measurements made within the packing. Substantial gas phase channeling was observed. Characterizing the gas flow regime by both piston flow and axial diffusion models yielded mass transfer data and computed axial gas concentration profiles. Differences between the mass transfer results for the two models allowed the influence of axial dispersion to be assessed. Comparison of the piston flow and axially dispersed profiles with the experimental profiles enabled conclusions to be drawn regarding the applicability of the axial diffusion model and the accuracy of available dispersion parameter values.The axial diffusion model appears to be a satisfactory representation of the process. The dispersion coefficients used were found to be too high, which emphasizes shortcomings in the transient response experiments yielding dispersion coefficients. The influence of dispersion on the performance was found to be only moderately adverse. The effect increases with increasing liquid rate, decreasing gas rate, and decreasing packing height. It is improbable that the effect is large enough to account for the difference between industrial scale performance and that predicted from available mass transfer correlations.
Viscosity and thermal conductivity of nitrogen—n‐heptane and nitrogen—n‐octane mixtures
Authors: Carmichael L. T. , Sage B. H. 
Published: June 2004

AbstractMeasurements of the thermal conductivity and viscosity ofn‐heptane andn‐octane in the gas phase were made at temperatures of 100° and 160°F. and at pressures below 1 atm. In addition, measurements of the viscosity and thermal conductivity of binary gas mixtures of nitrogen andn‐heptane were made at 160°F. at pressures below 1 atm.
Bubble growth by dissolution: Influence of contact angle
Authors: Buehl W. M. , Westwater J. W. 
Published: June 2004

AbstractThe rate of growth of bubbles forming on a wall from a liquid initially uniformly supersaturated with a dissolved gas was investigated. Attention was directed to the effect of the contact angle.Theoretical predictions for the growth rate of a spherical bubble tangent to a wall were carried out with a digital computer. The predictions included the diffusion equation and the continuity equation. The energy equation was neglected; viscosity and surface tension were assumed nil. The results are compared with existing predictions for a 90‐deg. contact angle. For extremely slow growth, the theoretical growth coefficient is about 30% smaller for a bubble with zero contact angle compared to one with a 90‐deg. contact angle. For fast growth the difference is much less.Experimental growth rates were determined photographically for bubbles of carbon dioxide coming out of solution from water at an artifical nucleation site. Different contact angles from 15 to 89 deg. were obtained by coating the wall with various nonwetting agents. Every bubble showed changes in its contact angle during growth. No effect of contact angle on the growth rate could be detected.
Application of the Benedict‐Webb‐Rubin equation of state to argon
Authors: Zudkevitch David , Kaufmann Thomas G. 
Published: June 2004

AbstractThe coefficients of the Benedict‐Webb‐Rubin equation of state have been developed for argon. By employing these coefficients, the volumetric behavior of argon has been predicted with an average deviation of 0.241% for five hundred ninety‐seven smoothed and experimental data points in the superheated region.At temperatures below the critical, two sets of Co's, one for the liquid and one for the vapor, were needed to relate the vapor pressure to the densities of saturated argon. However, consistent fugacities for the saturated vapor and liquid argon could not be predicted with these Co values. Therefore, another set of Co's was developed by equating the pure component vapor and liquid fugacities along the vapor pressure curve. These values were used to test the applicability of the equation of state to predict derived thermodynamic properties.The original BWR expression for calculating isothermal pressure effects on enthalpy was modified to include explicitly the temperature dependence of the coefficient Co. Vapor‐liquid equilibrium relations for the argon‐nitrogen system predicted by the standard BWR procedure were compared with experimental data.
Local thermodynamic consistency of vapor‐liquid equilibrium data for binary and multicomponent systems
Authors: Stevenson F. D. , Sater V. E. 
Published: June 2004

AbstractThe Gibbs‐Duhem equation, integrated over specific concentration ranges, is used to determine local thermodynamic consistency of vapor‐liquid equilibrium data. Several specific applications of the test are given for binary systems, although the method is equally applicable to linear paths in multicomponent systems. The test is particularly useful for evaluating the consistency of incomplete data, that is, data measured over only part of the concentration range.