bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonisothermal adsorption in fixed beds
Authors: Meyer Oscar A. , Weber Thomas W. 
Published: June 2004

AbstractRemoval of methane from a helium stream by adsorption on Columbia SXC activated carbon was studied experimentally and theoretically. A mathematical model for the process was developed and the governing differential equations were solved numerically. The model incorporates heat and mass transfer resistances within and around the adsorption particle. Wall effects and moderate heat loss to the surroundings are also included. The required heat and mass transfer correlations were obtained from the literature. Simple expressions were developed to determine the relative resistances for heat and mass transfer within and around the adsorption particles.
Determination of transient plate efficiencies from operational data
Authors: Groves D. M. , Tetlow N. J. , Holland C. D. 
Published: June 2004

AbstractMethods are presented for the determination of the transient values of the vaporization efficiencies from the knowledge of various combinations of the transient values of operating variables. For the case where the temperature and the composition of the liquid phase for each plate are known, a direct solution for the vaporization efficiencies is presented. Also, a method is presented for the determination of the mixing parameters of a generalized plate model on the basis of known transient values of certain operating variables.
Equilibrium stage calculations
Authors: Tierney John W. , Bruno Joseph A. 
Published: June 2004

AbstractIterative methods for the determination of stage temperature and interstage flow rates in the equilibrium stage problem are discussed, and the use of the Newton‐Raphson method for solution of the systems of simultaneous equations is proposed. It is shown that the complete correction process can be divided into four independent parts, two of which are treated in the paper. The first is equivalent to the constant molal overflow problem in distillation and the second to the constant temperature extraction problem. For each of these cases the necessary partial derivatives describing the effects of temperature and flow rate changes on all material balance equations are developed. Sample problems are briefly discussed to demonstrate the feasibility of the calculation and the fact that quadratic convergence is obtained. Equation derivation is simplified by using matrix notation, which also has the advantage that any interstage flow pattern is allowed.
A stochastic mixing model for homogeneous, turbulent, tubular reactors
Authors: Kattan Abraham , Adler Robert J. 
Published: June 2004

AbstractA stochastic mixing model is developed for turbulent flow in homogeneous plug‐flow reactors. The model is based on random coalescence and redispersion of fluid elements. Of special significance is its applicability when mixing and reaction rates are comparable, as well as when either rate dominates. The model's parameters may be determined by measuring conversion with instantaneous reactions. Experimental results reported by others are successfully simulated.
Prediction of the Joule‐Thomson coefficients of a gas mixture from a generalized equation of state: The nitrogen‐ethane system
Authors: Stockett A. L. , Wenzel L. A. 
Published: June 2004

AbstractUsing a thermodynamically consistent form of equation of state proposed by Foulkes, one can determine the virial coefficients of the pressure expansion from Joule‐Thomson coefficient data. A modification of the method has been applied for nitrogen and ethane within the temperature range from 50°C. to the normal boiling point. Mixture rules are proposed that allow reproduction of experimental data on μ for nitrogen‐ethane mixtures at pressures below the critical pressure of ethane.
A static vapor pressure apparatus for mixtures
Authors: Davison R. R. , Smith W. H. , Chun K. W. 
Published: June 2004

AbstractA static vapor pressure apparatus is described which is especially suitable for mixtures. A vapor pressure flask with a built‐in condenser allows the mixture to be degassed without change in composition. The entire apparatus is assembled from simple parts. Equilibrium is rapidly attained with either an external pressure or a liquid of known vapor pressure used as a reference.
Three turbulent drag coefficients in beds of spheres
Authors: Tallmadge John A. 
Published: June 2004

AbstractForm, shear, and total drag have been studied in the 2,500 to 65,000 range of Reynolds number over a wide range of porosity by using the data of Thodos and co‐workers. The effect of Reynolds number was found to be the −0.14 power for form drag, the −0.19 power for total drag, and the −0.5 and highe power for shear drag, so that the ratio of shear drag to total drag decreased from about 16% to less than 5% with increasing Reynolds numbers. For the 2,500 to 6,000 range of Reynolds number, experimental evidence supports the apparently analogous behavior between average shear drag and average heat flux. Limitations and related evidence of this behavior are also discussed. Methods are suggested for estimating drag ratios and coefficients by using the correlation of this work.
The streaming potential fluctuations in a turbulent pipe flow
Authors: Liu Henry 
Published: June 2004

AbstractAccompanied by a bried theoretical consideration, the results of an experimental study of the streaming potential fluctuations in turbulent pipe flows of distilled water are presented. The dependence of the streaming potential fluctuations on turbulent velocity fluctuations and other parameters as indicated by the theory is determined from the experimental data. Information on the characteristics of turbulent velocity fluctuations in the viscous sublayer near a pipe wall have been inferred from the data.
A theoretical analysis of some interrelationships and mechanisms of heat and mass transfer in dispersions
Authors: Gal‐Or Benjamin , Walatka Vernon 
Published: June 2004

AbstractSome of the main interrelationships that govern heat and mass transfer in dispersions are considered. Qualitative and quantiative analyses of the effects of holdup, average residence time, surface active agents, viscosity, and average particle size on transfer rates are made for two major domains. In the first domain a convective mass transfer model is formulated for the case of low dispersed phase holdup values and a steady motion of a swarm of bubbles with clean interfaces. A second domain is established for high dispersed phase holdup values and fine dispersions that contain surfactants. A semidynamic model for unsteady state heat (or mass) transfer from a swarm of droplets in a multistage liquid‐liquid disperser is demonstrated in this domain by a simultaneous solution of two differential equations (one for each phase).
Mass transfer from large single bubbles at high reynolds numbers
Authors: Nate Takayuki , Himmelblau D. M. 
Published: June 2004

AbstractSingle bubbles of carbon dioxide were formed in a fixed position surrounded by a thin conical film of water flowing at average film Reynolds numbers in the range of 40 to 300. Measurements of interphase mass transfer at 32°C. and various bubble pressures agreed with predicted values only for the smallest bubbles. For larger bubbles, mixing perpendicular to the bubble interface was enhanced by waves, believed to be generated by the unstable interface. A comparison of interphase transfer coefficients between this investigation and previous work indicated that the bubbles at the lowest flow rates qualitatively fell in line with other measurements, but that the highest water flow rates gave distinctly higher coefficients.
Diffusion coefficients of hydrogen and helium in water
Authors: Ferrell R. T. , Himmelblau D. M. 
Published: June 2004

AbstractMeasurements of laminar dispersion in a capillary have been used to determine the molecular diffusion coefficients of hydrogen and helium dissolved in water over the temperature range of 10° to 55°C. Literature correlations did not predict realistic values of the diffusivities for the hydrogen—water and helium—water binaries. A statistical analysis of the experimental diffusion coefficients indicated that they could be related to the absolute temperature by a semiempirical correlation, which may be considered an extension of the well‐known Wilke‐Chang correlation. This relation was based on the absolute reaction rate model of liquids.
Normal freezing of eutectic forming organic mixtures
Authors: Cheng C. S. , Irvin David A. , Kyle B. G. 
Published: June 2004

AbstractNormal freezing of several organic systems exhibiting simple eutectic behavior has been studied experimentally, and the occurrence of constitutional subcooling has been clearly established. This phenomenon, previously observed in systems of metallurgical interest, results in the instability of a planar solid‐liquid interface and leads to solute trapping. This trapping mechanism quantitatively explains why eutectic forming systems exhibit solid phase concentration profiles identical to those expected of systems which form solid solutions. The onset of constitutional subcooling can be correlated and reliably predicted by theoretical equations.Although the process of normal freezing with no liquid phase agitation would appear to be well described by a diffusion model, free convection induced by concentration gradients renders a boundary‐layer model more appropriate when the liquid density of the solvent exceeds that of the solute and freezing is in an upward direction.
A gravity corrected theory for cylinder withdrawal
Authors: White David A. , Tallmadge John A. 
Published: June 2004

AbstractThe speed range of the low‐speed theory for cylinder withdrawal is extended by a correction for gravity and a modified use of the thin meniscus assumption. Experimental evidence indicates that this gravity corrected theory holds over a 3,000‐fold range of speed, in terms of capillary number. This gravity corrected theory reduces, as special cases, to several other previously published theories as well as to the low‐speed theory.
Incorporation of ionic impurities in crystals growing from solution. The case of lead ions in potassium chloride crystals
Authors: Botsaris G. D. , Mason E. A. , Reid R. C. 
Published: June 2004

AbstractSingle seed crystals of potassium chloride were grown from aqueous solutions under conditions of constant temperature, supersturation, and impurity concentration. With emission spectrography as the method of analysis, the distribution of various metal ion impurities between the grown potassium chloride crystal and the solution was studied. The distribution coefficients of Pb++, defined as the ratio of the impurity concentration in the crystal to the concentration in solution, were found to be greater than unity at very low concentrations. The lead distribution coefficients varied between 2,700 for solutions containing 10−8 moles of lead/mole of potassium chloride to 28 (for solutions of 10−5 moles of lead/mole of potassium chloride).The results suggest a mechanism of nonequilibrium capture of the impurity. The magnitude of the distribution coefficient is shown to depend on the equilibrium distribution coefficient between the solution and surface of the crystal, the rate of growth of the crystal, and the rate of diffusion of the impurity through the crystal lattice. These results are believed to be of significance in the purification of materials by fractional crystallization. For instance, they indicate that in order to produce crystals of lead‐free potassium chloride, the conventional techniques or recrystallization should be modified to include rejection of the first crystals grown.
The injection method of determination of partial volume at infinite dilution
Authors: Hensel B. H. , Edmister W. C. , Chao K. C. 
Published: June 2004

AbstractA new experimental method of determining partial volume is described. The method requires the measurement only of a series of absolute and differential pressures. It is applicable to the determination of the partial volume of an infinitely dilute solute in a gas mixture up to high pressures. Measurement by this method can be readily performed at conditions of temperature and pressure so far unexplored to yield essential data for equation of state analyses.
Thermal dynamics of a distributed parameter nonadiabatic humidification process
Authors: Stewart Richard R. , Bruley Duane F. 
Published: June 2004

AbstractResults of a theoretical and experimental study of the thermal dynamics of a distributed parameter nonadiabatic humidification process are presented. A wetted‐wall column was selected for study to ensure standard and reproducible velocity profiles and a definable area for heat and mass transfer. Four mathematical models which consider various heat and mass transfer. Four mathematical models which consider various heat and mass transfer effects were derived in the time domain and solved in the frequency domain. All models, including a simple model previously tested for the adiabatic humidification case, were in good agreement with experimental results obtained by pulse testing.
Mixing and contacting models for fluidized beds
Authors: Mireur John P. , Bischoff Kenneth B. 
Published: June 2004

AbstractParameters of the two‐phase model for mixing in fluidized beds were evaluated from a large amount of available literature data. The dense phase dispersion coefficients and the cross flow, or interphase transfer, coefficients, based on the consistent model calculations, were correlated with operating conditions. A strong effect of bed length‐to‐diameter ratio was found for the dense phase mixing but not for the cross flow. On the basis of the given kinetics information with the mathematical model parameter correlations, some chemical reactor conversions from the literature were predicted by a priori calculations.
Viscosities and densities of methane‐propane mixtures at low temperatures and high pressures
Authors: Huang E. T. S. , Swift G. W. , Kurata Fred 
Published: June 2004

AbstractThe viscosities and densities of methane‐propane mixtures were determined at pressures to 5,000 lb./sq.in.abs. for 22.1 and 50.0 mole % methane over a temperature range from −120 to 37.78°C. and for 75.3 mole % methane over a temperature range from −150° to 37.78°C. Reproducibility of the viscosity data was ± 2%, and the agreement with literature values was, on the average, within ± 2%. The reproducibility of the density data was ± 0.8%, and the agreement with literature values was ± 1.2%.
Transport of gases through insoluble monolayers
Authors: Sada Eizo , Himmelblau D. M. 
Published: June 2004

AbstractThe reduction in gas desorption through surface active monolayers on a water substrate has been investigated for five compounds (1‐hexadecanol, 1‐octadecanol, 1‐docosanol, 1‐eicosanoic acid, and 1‐docosanoic acid) and four gases (oxygen, nitrogen, methane and carbon dioxide) at 25°C. Gas transport was retarded significantly at high surface coverage and decreased nonlinearly with change in surface coverage past the point equivalent to zero surface pressure.Interphase mass transfer coefficients for transport through the films were calculated, but no simple correlation could be discovered which could be used to predict film coefficients or the reduction as a function of surface coverage.
A study on stability and incipient turbulence in poiseuille and plane‐poiseuille flow by numerical finite‐difference simulation
Authors: Dixon T. N. , Hellums J. D. 
Published: June 2004

AbstractA difference method for treating the complete two‐dimensional Navier‐Stokes equations in time‐dependent form is applied to the prediction of incipient turbulence. A steady laminar flow profile is disturbed and the propagation of disturbances in time and space is calculated. Changes occur in amplitude and in character much as would be observed in a laboratory experiment. The classical paradox of stability of Poiseuille flow to low amplitude disturbances at all Reynolds numbers is studied and contrasted to plane‐Poiseuille flow. The amplitude dependence of stability is demonstrated. The results are shown to be consistent with prior theoretical and experimental work. The work lends strong support to the difference approach to difficult stability problems.
Third virial coefficients of nonpolar gases and their mixtures
Authors: Chueh P. L. , Prausnitz J. M. 
Published: June 2004

AbstractWhile much attention has been given to second virial coefficients of nonpolar gases, experimental and theoretical studies on third virial coefficients are scarce. This work presents a correlation of third virial coefficients within the framework of the corresponding states principle. The correlation is useful for estimating third virial coefficients of pure and mixed nonpolar gases, including the quatum gases helium, hydrogen, and neon. The importance of third virial cross coefficients in phase equilibrium predictions is illustrated with calculations for the solid‐gas, methane‐hydrogen system at 76°K.Brief attention is given to the pressure series form of the virial equation. Because of fortuitous cancellations, it is shown that for reduced temperatures above 1.4, the pressure series, truncated after the second term, is applicable to a wider range of density than the density series truncated after the second term. However, when both series are truncated after the third term, the density series appears to be superior regardless of reduced temperature.
Photochlorination of propane
Authors: Cassano Albert E. , Smith J. M. 
Published: June 2004

AbstractThe chlorination of propane was studied in a tubular flow reactor, with outside illumination, at atmospheric pressure. At chlorine concentrations of less than 1.5 mole % (and inert nitrogen above 94%) a second‐order (in chlorine) rate expression was indicated. At higher chlorine or propane concentrations propane affects the rate. Two rate equations, based upon different termination steps for the chain carriers, were found to fit the data. For the low concentration region the apparent activation energy for the overall reaction was 3.4 kcal./g.‐mole. Most of the measurements were carried out with polychromatic light, but data taken with a narrow band of radiation, over the range 2,200 to 5,400Ā, showed an increase in rate with decreasing wave length. As a first step toward reactor design, differential reactor data were used to predict the conversion for laminar flow, integral reactor conditions. A reactor model which included the effects of residence time distribution and radial variation in light intensity gave good agreement with experimental data. A plug‐flow model was less satisfactory.
The optimality of an easily implementable feedback control system: An inverse problem in optimal control theory
Authors: Denn Morton M. 
Published: June 2004

AbstractIn most control applications in the chemical process industries it is not realistic to attempt to define a unique mathematical statement of the control objective, for many criteria will satisfy the physical requirement of the rapid elimination of errors in the product stream as the result of an upset. The strong dependence of the structure of an optimal control system on the choice of objective then makes optimal control theory irrelevant in such situations, since the control engineer has no assurance that a complicated controller is a necessity of the process, rather than a consequence of an unfortunate choice of objective. In this paper an inverse problem is considered, in which an easily implementable feedback control system is first chosen and then is shown to be optimal for a physically meaningful objective in a large class of systems.
Kinetics of complex isothermal reversible first‐order reaction systems involving three components
Authors: Faith Larry E. , Vermeulen Theodore 
Published: June 2004

AbstractA new calculation method presented here for interpreting batch or tubular‐flow reactor data (and also CSTR data) on three‐component, three‐reaction reversible systems is based upon the general analyses of Jost and of Wei and Prater. With advance knowledge of the pertinent equilibria, even a very few experimental points can be matched easily and rapidly to the given figures and equations. The simplification involved when one reaction disappears, with the divariant system thus becoming monovariant, is also described. Representative concentration‐time curves are given for design purposes.
Concentrated polymer solutions: Part III. Normal stresses in simple shear flow
Authors: Williams Michael C. 
Published: June 2004

AbstractA molecular theory for the stress P in a concentrated polymer solution is evaluated for simple shear flow. Three rheological functions (P12, P11 − P22, P11 − P33) are predicted to be dependent on shear rate γ in a very complicated fashion, and are displayed graphically. A unique feature is that P22 − P33 is shown to have the same sign as P11 − P33 at low shear, a result in agreement with most experimental data and not predicted by other theories. A comparison with two sets of data verifies the prediction of relative behavior of shear and normal stresses at low γ, but the theory fails to fit data at high γ. Reasons for the success of the reducing factors c2 or c3 (where c is mass concentration) in constructing master curves for normal stress are suggested.
Transient multicomponent diffusion with heterogeneous reaction
Authors: Hudson J. L. 
Published: June 2004

AbstractThe problem of transient multicomponent diffusion of an arbitrary number of components in one‐dimension with heterogeneous reaction has been solved exactly by means of the Laplace transform. Linearized expressions for the diffusion and reaction were used. Numerical evaluations of the solution are given and a comparison made with results derived by use of an effective diffusivity.
The control of nonlinear systems: Part IV. Quasilinearization as a numerical method
Authors: Rothenberger B. F. , Lapidus Leon 
Published: June 2004

AbstractFive different variations on the basic quasilinearization algorithm for optional control are applied to a six‐variable nonlinear gas absorber system. Convergence of the algorithms to the optimal trajectory with better than 1% accuracy is achieved in less than ten iterations. The region of initial starting points which yield convergence is quite large. The main difficulty encountered is due to instabilities of the maximum principle equations. This limitation is, however, not severe and it is possible to predict a priori when the difficulty will occur. It is concluded that quasilinearization is a feasible algorithm for the optimization of nonlinear unconstrained systems.
Convective diffusion in stagnation flow with an imperfect semipermeable interface
Authors: Zeh Dale W. , Gill William N. 
Published: June 2004

AbstractIn this note convective diffusion in stagnation flow is discussed in the context of membrane separation processes, reverse osmosis in particular. It is shown that this is a desirable configuration for determining the rejection parameter R, a measure of how imperfect the semipermeable membrane interface is, because the dimensionless concentration function depends only on η.A simple approximate analytical solution is developed for (wsw/wse) which applies to separation processes in general. For reverse osmosis, NSc ≃ 560 and in this case the approximate results are compared with exact numerical calculations. It is found that the analytical solution is very accurate up to a polarization of (wsw/wse) ≃ 4 which constitutes a wide range of practical interest. For completeness, numerical results are reported up to a polarization of about 30.
Quasilinearization in optimization: A numerical study
Authors: Lee E. Stanley 
Published: June 2004

AbstractThe quasilinearization technique is used to obtain numerical answers for optimization problems formulated by the calculus of variations and the maximum principle. The optimum temperature profile in a tubular reactor, together with its initial optimum pressure, is obtained by this technique. Various variations of this problem such as control variable inequality constraints and the presence of pressure drop in the reactor are also discussed.