bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bubble formation in viscous liquids under constant flow conditions
Authors: Kumar R. , Kuloor N. R. 
Published: March 2009

AbstractBubble formation from single nozzles has been studied in liquids of different viscosities. The viscosity is varied in the range 50 to 500 c.p., whereas flow rates up to 100 cm3/second have been investigated. A model based on a two step (viz. expansion and detachment) mechanism has been proposed for bubble formation. The model explains the results of the present investigation as well as those reported in the literature for similar systems. As an extreme case, the model is tested on liquids of very low viscosity after dropping the viscosity terms from the equations and is found to explain even these data quite well.
Transport phenomena under unsteady conditions in an agitated vessel
Authors: Rajan V. S. V. , Picot J. J. C. 
Published: March 2009

AbstractAn experimental study of transport phenomena at the wall of an agitated vessel with a propeller impeller under unsteady conditions is reported. The transient in heat transfer at the wall is caused by a step change in the speed of agitation from an initial static condition. The results are expressed in terms of a rise in modified “j‐factor” above the initial free convection value and the number of revolutions taken by the impeller from the start of agitation. Also, an attempt has been made to find an analogy beween heat and momentum transfer. Results are given for the power in terms of Euler number plotted against the impeller Reynolds number. An empirical expression is also given for the transient heat transfer considering the system as a pure first order one with time delay. A “time‐factor” constant which gives the number of impeller revolutions for 63.2% of the change from the initial to a final steady state is expressed as a function of impeller Reynolds number (102 to 106) and fluid Prandtl number (6 to 106).
The accuracy of kinetic parameters estimated from batch and integral reactor data
Authors: Ravimohan A. L. , Chen W. H. , Seinfeld J. H. 
Published: March 2009

AbstractThe accuracy of rate constant estimates obtained by minimizing the sum of squares of differences between observed and calculated concentrations is considered. Closed solutions are obtained for some basic types of first order reaction schemes. The results are presented in the form of plots of the dimensionless variance of parameter estimates. The kineticist can use the plots both in analyzing experiments and in planning them for maximum economy. Such advance studies are capable of providing valuable insight into questions of experimental design even when the reaction scheme is unknown.
Langmuir‐temkin‐pyzhev rate models for ammonia decomposition reaction
Authors: Takezawa Nobutsune , Mezaki Reiji 
Published: March 2009

AbstractExisting rate data of ammonia decomposition were correlated using the Langmuir‐Temkin‐Pyzhev models and the applicability of those models was examined. Conventional statistical tests indicated that the Langmuir‐Temkin‐Pyzhev model was adequate, but the physico‐chemical examination of parameter estimates showed that the model was not feasible. The Temkin‐Pyzhev model was also employed to describe the decomposition data and discussed.
Transport properties of simple non polar binary liquid mixtures
Authors: Brunet J. , Doan M. H. 
Published: March 2009

AbstractTheorems of corresponding states for predicting the temperature and density dependence of liquid mixture transport properties are presented. The technique is tested for thirteen systems of spherical molecules (eight cryogenic mixtures, and five others) in which viscosity is predicted within 3%. For cryogenic mixtures, temperatures range from the triple point to temperatures close to the critical. In the present method, the only quantities required are pair potential parameters between like pair interactions, as determined from gas phase viscosity measurements, and pure component data.The lack of accurate measurements of thermal conductivity and diffusivity (mutual or self diffusion coefficients) for mixtures of spherical molecules(1) does not make it possible to test the present theory of those transport properties.
An improved method for numerical solution of distillation processes
Authors: Gentry James W. 
Published: March 2009

AbstractA new method for the numerical solution of a stagewise process is presented. The method consists of total linearization of all the equations in the distillation process, using the method of quasi‐linearization. The resulting equations form a block‐band matrix which can be readily solved by a method developed by the author. The method used for obtaining convergence is presented.The method has been tested for both binary and multi‐component systems. The method has been compared with the Amundson‐Pontinen method for a five component mixture. The method gives more rapid convergence. Numerical experiments indicate that the vapor and liquid flow rates are more stringent requirements than the bubble point.
Continuous flow mixing of two miscible liquids of different densities
Authors: Pelletier Martin , Cloutier Leonce 
Published: March 2009

AbstractPositive step demands hsve been used to study the behavior of miscible liquids with different densities in an imperfectly mixed cylinderical flow tank. A model was elaborated to predict the response of the agiated system. Comparisons between experimental and theoritical results have shown the limits of the proposed model and equations.
Turbulence parameters in a stirred tank
Authors: Mujumdar A. S. , Huang B. , Wolf D. , Weber M. E. , Douglas W. J. M. 
Published: March 2009

AbstractMean and fluctuating radial velocities have been measured in the inipeller stream of a baffled, turbine‐agitated cylindrical tank. Auto‐correlation functions, energy spectra and amplitude probabilitv density functions of the radial velocity fluctuations were also obtained. In the vicinity of the impeller, the motion is distinctly periodic, with a time scale corresponding to nbN/60, where nb is the number of turbine blades and N is the rpm. The amplitude of the periodic component was found to decrease with radial distance from the inipeller tip and was used to correct the measured turbulence intensities.
Transition phenomena in an oscillating manometer
Authors: Park J. R. S. , Baird M. H. I. 
Published: March 2009

AbstractThe decay of oscillation of a liquid column in a manometer has been studied. Measured values of the damping coefficients in laminar conditions agree well with previous data. The transition between turbulent and laminar damping has also been measured. For transition to fully developed turbulent flow, the critical Reynolds number is a function only of the Valensi number. In situations where turbulence exists at the ends of the liquid column but laminar conditions persist in the main section, the transition Reynolds number and damping exponent are functions of frequency and kinematic viscosity as well as Valensi number.
Gibbs free energy and activity coefficients from total pressure measurements
Authors: Minh D. C. , Rvel M. 
Published: March 2009

AbstractImprovements of an existing method for the calculation of the Gibbs free energy and activity coefficients for binary non‐ideal solutions from total pressure measurements are presented. These improvements are particularly significant whenever the ratio of the vapor pressures of the pure components is greater than 10. The convergence is rapid and the method is well adapted to digital computation.
Annular flow of two immiscible liquids II. Analysis of core‐liquid ascent
Authors: Hasson D. , Nir A. 
Published: March 2009

AbstractAn analysis was made of the core‐liquid trajectory in the horizontal‐pipe flow of two annular immiscible liquids with a density difference. Evaluation of the vertical drag force resisting buoyancy was based on approximating the peripheral wall‐liquid drainage by local Couette flow integrated over the drainage passage. Inertia‐effect corrections to the Stokes solution were also taken into account from available information.Experimental wall‐liquid thicknesses, measured from highspeed photographs, were in excellent agreement with predicted trajectories for the case of a non‐wavy interface, as assumed in the model. With a wavy interface, upper‐film thickness was considerably larger than predicted, suggesting that in spite of their disrupting tendency, the waves also contribute towards annular‐flow stability.
Excitation of spontaneous vibrations in enclosed diffusion flames
Authors: Deckker B. E. L. , Sampath P. 
Published: March 2009

AbstractThe presence of Tollmien‐Schlichting waves during the initial stages of the isothermal mixing of two axi‐symmetical laminar streams of air has been confirmed by comparing data from hot wire measurements with published two‐dimensional theoretical and experimental results for the stability of mixing and for transition in a boundary layer. Hot wire measurements in the flow field of steady or vibrating axi‐symmetrical laminar diffusion flames are remarkably similar to those obtained during isothermal mixing. A travelling wave in the mean flow direction has also been established. Data for these flames agree with the results of a higher order stability analysis for natural convection flow past a vertical heated plate. It has been concluded that Tollmien‐Schlichting waves are responsible for exciting flame vibrations.
End effects on interphase heat and mass transfer in a cubically packed bed of spheres
Authors: Clark Craw , Epstein Norman 
Published: March 2009

AbstractHeat (and mass) transfer data were obtained for the constant rate evaporation of water from two layers of porous spheres in simple cubic array (ϵ = 0.4764) to a flowing air stream, over a particle Reynolds number range of 200‐900.It was found that the cumulative effect of adding inert layers of non‐porous spheres at the entrance and exit was to lower (rather than raise, as in the case of randomly packed beds) the extent of heat and mass transfer between the active spheres and the fluid, the minimum number of inert layers required to eliminate end effects being three at the entrance and two at the exit. The specific effect of adding only one inert layer to the entrance, with none at the exit, was to raise somewhat the extent of heat and mass transfer. Interpretations are offered for these trends.The simple cubic assemblage showed substantially lower values of the heat (and mass) transfer factors than those of randomly packed beds.
The production of synthetic crude oil from oil sand by application of the lurgi‐ruhrgas‐process
Authors: Rammler R. W. 
Published: March 2009

AbstractSynthetic crude oil can be produced from oil sand by application of the Lurgi‐Ruhrgas process which is characterized by the circulation of fine‐grained heat carriers. The process is described and information given on its commercial application to date, which relates to the cracking of hydrocarbons to olefins and the carbonization of fine‐grained coal.Reference is made to distillation tests on approx. 45 tons of raw oil sand. The yield of oil in commercial plants is expected to be approx. 95% by weight. Studies and computations show that beneficiated oil sand used as feedstock has advantages over raw oil sand.It is suggested that in a commercial plant beneficiation and LR distillation should be combined. Based on the present state of Technology LR units for an output of about 8,000 ‐ 12,000 bbl/day of crude oil could be built. The approximate capital and operating costs of such a unit are indicated. In closing, reference is made to further possible applications of the LR process.
Wheat drying in well‐stirred‐batch and continuous‐moving‐bed dryers
Authors: Becker H. A. , Isaacson R. A. 
Published: March 2009

AbstractEarlier studies established the physical chemistry and diffusion mathematics of wheat drying. This knowledge was applied in a mathematical model of continuous drying in a well‐stirred bed, and a good correlation of experimental results on spouted‐bed drying was obtained. Now a model has been formulated for both well‐stirred batch and continuous moving‐bed dryers of the commercial types. The set of mass and energy balances and rate equations has been solved numerically by digital computation. Heating and cooling cycles are both treated. Good agreement is found with the experimental data of Stansfield and Cook on a dryer simulating the performance of commercial moving‐bed dryers.
An analytical method applicable to the determination of individual concentrations of components, resulting from gamma induced iodination of methane
Authors: Vilenchich R. , Venter R. 
Published: March 2009

AbstractA method combining the least squares approach with the Monte Carlo technique applicable to a set of m simultaneous linear equations in n unknowns has been developed to determine the n unknowns when the coefficients of the m equations are subject to a known distribution. The method is superior to the standard method when no Monte Carlo strategy is used, since the distribution of the n unknowns about a mean value is now also calculable, and a better comparison with experimental data is possible.The method has been applied to the determination of the individual concentrations of components resulting from the gamma induced iodination of methane. The concentrations calculated by this method are compared to the actual measured concentrations used during experimentation.
Computation of chemical equilibrium compositions II
Authors: Storey S. H. , Van Zeggeren F. 
Published: March 2009

AbstractA simple modification to a previously described search method for the computation of chemical equilibria is presented. The modification consists of an automatic correction for any drift which normally arises with the search method. The drift correction also obviates the need for starting estimates which obey atom balance conditions. The modified method is both faster and more convenient to use than the method described previously.
Mass transfer with chemical reaction inside single droplets and gas bubbles: Mathematical mechanisms
Authors: Wellek R. M. , Andoe W. V. , Brunson R. J. 
Published: March 2009

AbstractThe effect of a first order homogeneous chemical reaction on the rate of mass transfer inside liquid droplets and gas bubbles was determined. One of the models presented assumes the non‐oscillating dispersed phase is moving in the creeping flow region and the Hadamard stream functions are applicable. The results of the numerical solution of this model are presented graphically as a function of the Peclet number, reaction number, and dimensionless contact time. An oscillating droplet model is also presented which considers the effect of reaction within the dispersed phase.
H2S promoted oxidative dehydrogenation of butenes — A new dehydrogenation technique
Authors: Vadekar M. , Pasternak I. S. 
Published: March 2009

AbstractA new technique, recently defined, uses an H2S/O2 mixture to selectively dehydrogenate hydrocarbons in high yields at temperatures of about 1100°F in the presence of suitable catalysts. In the new processing scheme, H2S is thought to react with oxygen to form reactive sulphur species capable of efficient hydrogen abstraction. The overall effect is thus the reaction between oxygen and hydrogen from the hydrocarbon to produce water and a more unsaturated hydrocarbon product.The above technique is discussed in some detail for the oxidative dehydrogenation of butenes to butadiene. The importance of selecting the appropriate catalyst is emphasized and the various processing variables affecting the overall reaction are described.
The prediction of the PVT properties of sour gas mixtures
Authors: Swinton F. L. 
Published: March 2009

AbstractRecent developments in the statistical mechanics of fluid mixtures due to Rowlinson and co‐workers have been applied to H2S/n‐alkane mixtures. The results have then been used to estimate the compressibility factor of a real sour gas mixture and the predicted theoretical value is found to be in excellent agreement with experiment.
Non‐steady, multi‐layered stratified flow
Authors: Pendergast D. , Cobble M. , Smith P. 
Published: March 2009

AbstractA solution to the problem of non‐steady, stratified laminar flow of incompressible fluids through horizontal conduits is presented. The method is able to treat stratified flows of an arbitrary number of layers through two dimensional conduits and concentric flows of an arbitrary number of layers through cylindrical conduits by using the technique of quasi‐orthogonalization.The validity of the method is tested by presenting results for a two‐layered start‐up flow in a two‐dimensional duct. As the time approaches infinity the velocity profiles calculated by this method agree with steady flow velocity profiles obtained by other authors.
On the measurement of liquid phase diffusivities for slightly soluble solids
Authors: Pradhan A. A. , Heideger W. J. 
Published: March 2009

AbstractA procedure is developed to measure diffusion coefficients in the liquid phase for slightly soluble solids. Transient concentration profiles for the dissolution of a planar solid surface are obtained by means of a Mach‐Zehnder interferometer. Fitting of these profiles to Fick's second law then provides a measure of the diffusivity, even when it is concentration dependent.Application of the technique to the water‐benzoic acid system yields a diffusion coefficient at 25°C which is 1.3 × 10−5 cm2/sec at infinite dilution and which decreases slowly as the concentration approaches saturation. The initial value for acetanilide in water is 1.1 × 10−5 cm2/sec at 25°C and again the diffusivity decreases as the concentration increases.
An investigation of the viscosity of dry air at elevated pressures and temperatures using a steady‐flow capillary viscosimeter
Authors: Goring G. E. , Eagan D. P. 
Published: March 2009

AbstractA steady‐flow capillary viscosimeter, using dry air as the test gas, has been demonstrated at 150, 230, 330 and 430° Centigrade and over a pressure range of 35–150 atmospheres. Measured viscosities showed a maximum isothermal increase of about 4%. An extrapolation procedure was used to correct for flow and temperature discrepancies and a modified Hagen‐Poiiseuille equation, using variables evaluated at the mean capillary temperature, was applied to those data taken under nonisothermal conditions. The overall assembly and technique are capable of relative viscosity measurements having a standard deviation within 11/2% in the cited ranges.
Time dependent rheology of artificial slurries
Authors: Brown J. P. , Pinder K. L. 
Published: March 2009

AbstractGels, formed by suspending cellulose acetate particles of regular shape and size in a Newtonian medium, were sheared in a rotational viscometer to study their time dependent rheological behavior. Qualitative observations of the effect of the well defined particle parameters, shape surface area and concentration on the flow parameters were made.The viscosity decay behavior fitted the model previously proposed by Pinder for slurries of natural particles.By considering the effect of the weighting salt used in the suspending medium, it was found that the theory that ionic forces are active in stabilizing the thixotropic gel structure was supported.
Velocity and temperature profiles in compressible turbulent wall jets
Authors: Vlachopoulos John 
Published: March 2009

AbstractThe results of an experimental study on compressible turbulent wall jets resulting from a normally impinging round jet are presented. A finite difference technique was used for the calculation of velocity and temperature profiles. The eddy transfer coefficients used were functions of the distance from the plate throughout the flow field of the wall jet. The nozzle exit Mach number ranged up to 0.85. The nozzle exit temperature to the ambient temperature ratio ranged up to 2.92. The applicability of the calculational method has been thoroughly checked for a region of flow extending up to 12 nozzle diameters from the axis of symmetry. Using the empirical eddy transfer coefficients presented in this paper only starting profiles are needed to generate the solution for any point in the wall jet flow field which is described by a system of parabolic (boundary layer) equations.
Mass transfer into a horizontal layer of stagnant liquid under the action of instabilities+
Authors: Ruckenstein E. 
Published: March 2009

AbstractThe rate of absorption into a horizontal liquid layer undergoing an assumed steady cellular convection due to a concentration gradient or to the Marangoni effect is calculated. One concludes that a roll‐cell model can explain the large increase in the rate of absorption observed experimentally and that for large times a diffusional model, with a constant diffusion coefficient much larger than the molecular one, describes adequately the above situations.
On the measurement of zeolitic diffusion coefficients
Authors: Loughlin K. F. , Derrah R. I. , Ruthven D. M. 
Published: March 2009

AbstractCrystal size distribution data and experimental sorption curves are presented for Linde 4A and 5A zeolites. It is shown that the deviation of the experimental sorption curves from the simple solution of the diffusion equation for spherical particles can be quantitatively accounted for by considering the shape and size distribution of the zeolite crystals. By working with well characterized samples of crystals it is thus possible to obtain reliable diffusivity data for rapid sorption processes by analysis of the sorption curves at intermediate and long times. The concentration dependence of diffusivity is briefly discussed.
Influence d'une agitation rotative sur le fonctionnement d'une colonne pulsée d'extraction
Authors: Subhasavasdikul S. , Alran C. , Boyadzhiev L. , Angelino H. 
Published: March 2009

AbstractLes auteurs proposent l'utilisation d'un nouveau type d'extracteur dans lequel ils superposent deux agitations, l'une de pulsation, l'autre de rotation. Après avoir étudié les conditions hydrodynamiques de leur appareil, ils comparent ses performances à celles d'appareils plus classiques fonctionnant en continu à contre courant. A l'aide de deux mélanges ternaires, ils ont établi que l'efficacité de leur appareil est supérieure à celle d'une colonne pulsée ou d'une colonne à disques rotatifs: les hauteurs d'unités de transfert sont réduites par un facteur pouvant atteindre 2.
A principle of equivalent states for liquid transport properties
Authors: Cullinan Harry T. 
Published: March 2009

AbstractA principle of equivalent states for liquid transport properties is developed for binary liquid systems. Under the assumption that the activity and viscosity corrected mutual diffusion coefficient is a function of the solution molar volume, working equations are developed for the concentration dependence of the binary mutual diffusion coefficients. The results apply to binary liquid systems for which the coefficient of thermal expansion is independent of composition and for which the difference in activation free energies for viscous flow and diffusion is also independent of composition. The results are tested with available data to show that the binary mutual diffusion coefficient can be predicted from the infinitely dilute values and the solution viscosity and thermodynamics for a large number of liquid systems.
Vapor‐liquid equilibria in the methane‐ethylene‐ethane system
Authors: Hsi Chu , Lu Benjamin C.‐Y. 
Published: March 2009

AbstractVapor‐liquid equilibrium compositions were measured for the methane‐ethylene binary at — 156.1°, — 173.1° and — 193.1° F, the methane‐ethane binary at — 173‐1° F, and the methane‐ethylene‐ethane ternary at — 173.1° F and at pressure up to 330 p.s.i.a. A forced recirculation apparatus was employed for the determinations. Liquid activity coefficients, γ, were evaluated by means of a modified Redlich‐Kwong equation of state incorporating with binary interaction constant and correlated by the Redlich‐Kister equation. Equilibrium data for the ethylene‐ethane binary system at — 173° F were predicted by the modified Redlich‐Kwong equation of state for correlating the γ values of the methane‐ethylene‐ethane ternary system.