bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non‐Newtonian flow in porous media
Authors: McKinley R. M. , Jahns H. O. , Harris W. W. , Greenkorn R. A. 
Published: June 2004

AbstractThis paper describes a preliminary study of the linear flow of a non‐Newtonian fluid, a water solution of Dextra (a polysaccharide), in porous media. A modification of Darcy's law, which uses capillary rheology data, is developed to describe non‐Newtonian flow in underground reservoirs. The generalization, in effect, replaces the porous media with a capillary of equivalent radius proportional to the square root of the ratio of permeability to porosity. The constant of proportionality αo should be independent of permeability and porosity for a given type of rock. This has been partially confirmed experimentally. In principle, a capillary rheogram and a single core test permit evaluation of αo. Then non‐Newtonian flow can be predicted in this type of rock regardless of porosity, permeability, or flow rate.
The influence of surface coverage on catalytic effectiveness and selectivity. The isothermal and nonisothermal cases
Authors: Hutchings John , Carberry James J. 
Published: June 2004

AbstractBoth nonisothermal and isothermal catalytic effectiveness factors are computed for kinetic rate laws of the Langmuir‐Hinshelwood, Hougen‐Watson type, involving surface coverage by reactant and products. Selectivity taxation is also treated and the significant influence of interphas heat and mass gradients surrounding the catalyst is displayed. The complexities of these real kinetic systems suggest caution in the use of prior generalizations based upon simpler rate laws.
Pressure drops and void fractions in horizontal two‐phase flows of potassium
Authors: Smith Lowell R. , Tek M. Rasin , Balzhiser Richard E. 
Published: June 2004

AbstractVapor‐liquid flow of a potassium‐8% sodium mixture was studied with the use of a boiling heat transfer test loop. Pressure drop data were obtained from a 36‐in. long, 0.495‐in. I.D. unheated test section. Void fractions were measured at the midpoint of the test section with gamma ray attenuation.Flows were essentially frictional. Quality, total flow rate, and absolute pressure were the principal variables affecting the pressure drop results, which were correlated in terms of a two‐phase friction factor. A metallic void fraction correlation was developed from previously reported data for other metallic fluids together with the potassium data of this study.The potassium two phase friction factors fall substantially lower than values predicted by well‐known frictional pressure drop correlations. Metallic void friction values are appreciably lower than data for other fluid systems. Velocity slip ratios appear to be much higher than for other fluid systems due to high liquid‐to‐vapor density ratios and low void fractions.
Forced convection mass transfer: Part III. Increased mass transfer from a flat plate caused by the wake from cylinders located near the edge of the boundary layer
Authors: Thomas David G. 
Published: June 2004

AbstractEnhanced rates of mass transfer in the wake region behind detached cylindrical turbulence promoters were investigated with the use of the naphthalene sublimation technique. The maximum increase in the average rate of mass transfer through laminar boundary layers was over 170%. The remarkable feature of these results was that the enhanced rates of mass trasfer persisted for over one hundred and thirty cylinder diameters downstream from the cylinder generating the wake. The observed effect was not only strongly dependent on the free stream velocity and the location of the cylinders relative to the mass transfer surface, but there were marked differences observed between the rate of mass transfer in the wake region behind one and behind two cylinders. These results resemble a “tuning phenomenon” and are believed to be due to Tollmein‐Schlichting instabilities and premature transition.
Velocity and pressure profiles for Newtonian creeping flow in regular packed beds of spheres
Authors: Snyder L. J. , Stewart W. E. 
Published: June 2004

AbstractA theoretical analysis is made of Newtonian creeping flow through dense cubic and simple cubic beds of spheres. Velocity and pressure profiles are obtained in equation form by Galerkin's error‐distribution method. The profiles satisfy the conservation equations approximately, and the boundary conditions and symmetry conditions exactly. The calculated friction factors are within 5% of experimental values for both packing arrangements.
A computational model for the structure of porous materials employed in catalysis
Authors: Foster Richard N. , Butt John B. 
Published: June 2004

AbstractA computational model for the structure of porous materials such as those employed in catalysis is proposed. The void volume within the solid is considered to be composed of two major arrays of pores, centrally convergent and centrally divergent, respectively, interconnected at specified intervals within the arrays. The exact shape of these arrays is determined uniquely from the volume‐area distribution of the porous structure.The model is applied to computation of counterdiffusional flux through a porous solid as measured in a Wicke‐Kallenbach experiment. The effects of dead end pores and of mixing on the results are discussed, and comparison with experimental data reported for a particularly well‐defined system is given.
The effect of wave induced turbulence on the rate of absorption of gases in falling liquid films
Authors: Jepsen J. C. , Crosser O. K. , Perry R. H. 
Published: June 2004

AbstractConcentration profiles for carbon dioxide diffusion into thin water films with waves flowing down an inclined plate have been determined. Film Reynolds numbers were varied from 732 to 1,834 at a cell angle of inclination of 9 deg. 44 min. Total diffusivities measured from the concentration profiles showed a marked increase in the central region of the film, with the diffusivity tending toward the molecular diffusivity at the boundaries of the film. Interferometer pictures of the concentration profile showed that the effect of the waves was to compress and expand the profile as the surface of the film changed, but indicated no direct effect on the variation of eddy diffusivity normal to the liquid surface.
Bubble motion and mass transfer in non‐Newtonian fluids
Authors: Barnett Stanley M. , Humphrey Arthur E. , Litt Mitchell 
Published: June 2004

AbstractInstantaneous mass transfer coefficients were obtained for the absorption of carbon dioxide bubbles rising in an aqueous solution of sodium carboxymethylcellulose. The rheological character of the solutions was well described by the Ellis model.Mass transfer coefficients were high initially but trailed off rapidly with bubble age. Exceptions were found at specific diameters where the bubble shape went through a transition. At about 0.2 cm. a transition from ellipsoidal to a sphere shape occurred, which has also been observed in Newtonian fluids. At a larger diameter, however, the non‐Newtonian fluid showed a shape change from a spherical “cap” to a “top” shape and finally to an ellipsoid. A sudden increase of mass transfer coefficient accompanied each shape transition.Drag coefficient data were correlated successfully with a new Reynolds number. The Newtonian and power law portion of the Ellis model each contributed a component to the Reynolds number, which, when added together, correlated drag data for the bubbles as well as for glass spheres.Attempts to account for transition shape changes and bubble tailing in the non‐Newtonian fluid and their effects on bubble mass transfer are included.
The kinetics of sorption by ion exchange resin beds
Authors: Colwell Charles J. , Dranoff Joshua S. 
Published: June 2004

AbstractThe kinetics of sorption of dilute aqueous solutions of acetone, n‐propanol, ethylen glycol, and glycerine by packed beds of Dowex 50W‐X8 (H+) resin have been investigated experimentally. Data indicate that intraparticle diffusion of the solute is rate controlling and that density mixing and nonlinear equilibrium effects must be considered in analyzing this type of operation.
Heat transfer to molten flowing polymers
Authors: Griskey Richard G. , Wiehe Irwin A. 
Published: June 2004

AbstractA precise, reproducible method has been developed for measuring temperature profiles in flowing molten polymers with heat transfer. Experimental data determined by this method showed that viscous dissipation occurred, but not at the level predicted theoretically. The difference between the actual and theoretical viscous dissipation was possibly due to flattening of fluid velocity profile, changing physical properties, and fluid viscoelasticity. Nusselt numbers calculated from the data checked thoretical Nusselt‐Graetz solutions.
Velocity distributions and normal stresses in viscoelastic turbulent pipe flow
Authors: Astarita Gianni , Nicodemo Luigi 
Published: June 2004

AbstractPitot tube readings in a viscoelastic turbulent stream are discussed thoretically, and are shown to be made up by a first normal stress contribution, an integral normal stress contribution, and a kinetic contribution. These three contribution are of comparable orders of magnitude. The integral of a Pitot tube scanning curve is shown to yield a momentum average factor of direct physical relavance. Experimental data show that the normal stress contributions are not negligible even in the central region of the pipe, although turbulent flow conditions were reached. Observed values of the relevant parameters are discussed.
Mass transfer from large oscillating drops
Authors: Rose P. M. , Kintner R. C. 
Published: June 2004

AbstractA mass transfer model for vigorously oscillating single liquid drops moving in a liquid field has been developed with the concepts of interfacial stretch and internal droplet mixing. The model takes into account both amplitude and frequency of drop oscillations. Experimental values of fraction extracted were predicted with an average deviation of 15%. Oscillations break up internal circulation streamlines and a type of turbulent internal mixing is achieved.
Gas bubble entrainment by plunging laminar liquid jets
Authors: Lin Tong Joe , Donnelly Harold G. 
Published: June 2004

AbstractA free, vertical jet of liquid plunging into a uiescent surface of the same liquid entrains the surrounding gas into the receiving liquid to form bubbles. The entrainment characteristics of such jets of Newtonian liquids of varying physical properties have been investigated by means of high‐speed photography.Although both laminar and turbulent jets entrain gas bubbles, the mechanisms governing the entrainment process of the two types of jets are clearly different. Entrainment by turbulent jets results from the disturbances on the free surface caused by the jet instability; entrainment by laminar jets is accomplished by the formation of a thin shell of gas around the jet at the point of entrance, by the development of oscillations in the shell, and by its subsequent breakup into bubbles.Entrainment occurs only when the average jet velocity exceeds a certain critical value termed minimum entrainment velocity. For a laminar jet having a flat velocity profile at the point of entrance, the following correlation permits prediction of the minimum entrainment velocity:

where the dimensionless numbers are based on the liquid properties and the jet diameter at the point where the jet meets the surface of the receiving liquid.
Surface catalysis of the hydrogen‐oxygen reaction on platinum at low temperatures
Authors: Leder Frederic , Butt John B. 
Published: June 2004

AbstractThe reaction between hydrogen and oxygen has been investigated at low temperatures with a dilute platinum catalyst. Experimental conversion data indicate a strong effect of product water on reaction rate and a second‐order dependence of rate on hydrogen partial pressure in the presence of a large excess of oxygen. This observed behavior is considerably different from expectations based on prior literature.Stable activity levels are much lower than those reported by Boreskov for this reaction on platinum; it is shown that present results are consistent with the effect of chemisorbed oxygen proposed by Boreskov and with the conditions imposed for reaction on a dilute catalyst. Activation energy for the reaction at 100°C. was determined to be 10± 2 kcal./g.‐mole.
The relaxation of concentration polarization in a reverse osmosis desalination system
Authors: Tien Chi , Gill William N. 
Published: June 2004

AbstractAn analysis of diffusional effects in a system consisting of impermeable relaxation sections placed alternately between semipermeable membrane sections indicates significant attenuation of salt concentration at the boundary in the impermeable section. The analysis employed exploits Equation (16), a relation deduced by Lighthill (4), to avoid the necessity of using orthogonal function expansions which converge slowly in the diffusion entrance region which is studied here.
Axial dispersion in liquid flow through packed beds
Authors: Miller Steven F. , King C. Judson 
Published: June 2004

AbstractStep‐function injection and purging of a dilute salt tracer in water was used to measure axial dispersion for low Reynolds number liquid flow through beds of uniform sized, random packed glass spheres. The resultant data and those of several previous studies are coordinated and interpreted in terms of Reynolds, Schmidt, and Peclet numbers.
Effect of axial diffusion of vorticity on flow development in circular conduits: Part I. Numerical solutions
Authors: Vrentas J. S. , Duda J. L. , Bargeron K. G. 
Published: June 2004

AbstractAn entrance model is presented which extends the analysis of the flow development in the entrance region to flow regimes which are inadequately described by a boundary‐layer analysis. Results are presented for the numerical solutions of the boundary‐layer equations and the complete equations of motion at five different Reynolds numbers. The effect of the axial diffusion of vorticity on the pressure drop, entrance length, and development of the vorticity and velocity fields is demonstrated.
Constitutive equations for viscoelastic fluids for short deformation periods and for rapidly changing flows: Significance of the deborah number
Authors: Metzner A. B. , White J. L. , Denn M. M. 
Published: June 2004

AbstractThe proper forms and asymptotic characteristics of constitutive equations which may be useful for the description of viscoelastic fluids in flow fields of engineering interest are considered. It is seen that the Deborah number emerges as a natural ordering parameter which determines, on the one hand, whether simple approximations explicit in stress may suffice to describe the fluid properties or, on the other hand, whether implicit or integral equations are required. Methods of scale‐up are discussed.
Mass transfer in supported forths
Authors: Workman Walter L. , Calvert Seymour 
Published: June 2004

AbstractOperating and mass transfer characteristics are reported for a supported froth apparatus consisting of a dual‐flow sieve plate column with eggcrate packing above the plate. The assembled packing produced a series of vertical tubes and served to support the froth generated at the plate, increasing its height and consequently the contact time. Addition of the packing improved the mass transfer efficiency. Systems studied were ammonia–air–water and carbon dioxide–air–water. Effects of liquid and gas rate as well as packing size and spacing are correlated. A model based on measurable physical parameters was developed to predict efficiency, and a generalized correlation of efficiency was developed.
Prediction of thermodynamic properties of dense gas mixtures containing one or more of the quantum gases
Authors: Gunn R. D. , Chueh P. L. , Prausnitz J. M. 
Published: June 2004

AbstractEffective critical constants for helium and normal hydrogen have been determined by fitting experimental volumetric data for these gases to the generalized tables of Pitzer. The effective critical temperature and pressure are found to depend on the temperature and on the molecular mass in a simple manner permitting good estimates to be made of effective critical constants for other quantum gases for which experimental data are scarce (neon, isotopes of helium and hydrogen). Pitzer's tables are used with pseudocritical mixing rules to predict thermodynamic properties of mixtures at high pressures and low temperatures. Calculated compressibility factors and enthalpies are in excellent agreement with experimental results for dense mixtures of hydrogen‐methane, hydrogen‐argon, and helium‐nitrogen.
Turbulent dispersion in a pipe flow
Authors: Becker H. A. , Rosensweig R. E. , Gwozdz J. R. 
Published: June 2004

AbstractThe nearly homogeneous, isotropic turbulence field in the core of a fully developed pipe flow was chosen as the medium for turbulent dispersion of a smoke tracer injected from a point on the centerline. By using the optical probe technique the fields of the mean and fluctuating point concentration were mapped at several Reynolds numbers, and spectral analyses made of concentration fluctuations on the plume axis. With the use of sheet illumination, the mean and fluctuating components of the integral material concentration in a plume cross section were measured and the fluctuating component was spectrally analyzed. The maximum Reynolds number was 684,000, the maximum ratio of root‐mean‐square concentration fluctuation to mean concentration exceeded 100% for points and 40% for sheets, and the turbulent Peclet number was found to equal 850. The existence of standard flow conditions was confirmed by measurement of the frictional drag coefficient and the mean concentration field.
A method of getting approximate solutions to the orr‐sommerfeld equation for flow on a vertical wall
Authors: Anshus Byron E. , Goren Simon L. 
Published: June 2004

AbstractA method is presented for getting approximate solutions to the Orr‐Sommerfeld equation for free surface flows. The method consists of replacing the velocity, normally a function of distance from the wall, by its value at the free surface while the second derivative of the velocity is kept at its true value. This permits a simple solution to the equation and the eigenvalues can then be determined by a simple and rapid numerical technique. Comparison of this approximate solution for the flow of a thin film on a vertical wall with existing exact numerical solutions and with analytical results valid only for small Reynolds numbers shows the approximation to be quite accurate for most practical values of the parameters and suggests that the method will be useful in investigating the stability of related flows.
Liquid surface area effects in a wetted‐wall column
Authors: Robert Reker J. , Plank C. A. , Gerhard E. R. 
Published: June 2004

AbstractVaporization of methanol and carbon tetrachloride into air and carbon tetrachloride into helium was carried out in a counterflow wetted‐wall column at 10° to 20°F. These data show an influence of liquid rate upon the mass transfer coefficients. Liquid rate influence has been empirically accounted for by a function of surface area increase caused by rippling of the liquid film.
Adsorption of hydrocarbon gas mixtures at high pressure
Authors: Preston Mason J. , Cooke C. E. 
Published: June 2004

AbstractAn experimental investigation was made of the adsorption or silica gel of components from light hydrocarbon mixtures, and the results were used to test a multicomponent adsorption theory. Experimental methods included a volumetric technique to measure pure component adsorption and flow techniques for adsorption from mixtures. Although the majority of measurements was made at 100°F., two mixtures were studied over the temperature range 40° to 160°F. Pressure was varied up to 1,800 lb./sq.in.abs. The Brunauer‐Emmett‐Teller (BET) theory of adsorption, as extended to mixtures by Hill, was tested against the experimental data and was found to be adequate for calculating adsorption from hydrocarbon mixtures of components heavier than methane. To account for nonideal behavior, the fugacity of each component in the gas and in the adsorbed phases was calculated by using the Benedict‐Webb‐Rubin equation of state. The differences in experimental and theoretical values for adsorption capacity were less than 10% for most of the conditions tested, but ranged up to about 25% for the highest pressures studied. Although the BET theory represents a simplified model of a complex process, it can be used to supply adsorption data for engineering application over ranges of pressure, temperature, and gas composition usually encountered in adsorption processing of natural gas mixtures.
Rate data and derivatives
Authors: Nevers Noel De 
Published: June 2004

AbstractIn most rate process problems, the original experimental data must be differentiated to obtain the derivatives, which are the information actually sought. For first derivatives all the commonly used methods give about the same result. However, the common methods of calculating derivatives can give very different second derivatives for the same set of starting data. Thus, in problems in which the desired result is a second derivative, the answer obtained is a strong function of the method used to calculate second derivatives. This is illustrated by several examples.
Photochlorination in a tubular reactor
Authors: Cassano Alberto E. , Smith J. M. 
Published: June 2004

AbstractA method of describing the behavior of a single‐phase, photochemical reaction in a tubular flow reactor is given. A simplified form of the equations is applied to experimental data for the chlorination of propane.The results indicate that the reaction rate is second order in chlorine concentration and first order in light intensity at the wall. Independent experimental actinometer measurements permit the determination of absolute values of the kinetic constants. Such data are rarely available for photochemical reactions. Filter solutions flowing through a jacket around the reactor is shown to be a practical method for studying the effects of light intensity, as well as for cooling the reactor. The optical efficiency of the reactor lamp system was 11%.
Reverse osmosis in annuli
Authors: Gill William N. , Zeh Dale W. , Tien Chi 
Published: June 2004

AbstractThe nonlinear problem of reverse osmosis in annular conduits is solved by a series expansion method which is very accurate in the diffusion entrance region near the inlet of the membrane section. It is found that polarization at the outer membrane surface is significantly greater than at the inner wall.In the diffusion entrance region, for the problem considered, the degree of polarization depends on the three parameters, σ, and B2, which are known once the operating conditions and the physical properties of the system are specified. The quantities θi (0) are tabulated for a wide range of ηk and B2. With these quantities known one can apply Equation (17) at β = 0 to calculate the wall concentration distribution and, with Equation (4), the flux distribution along the system. Then, by using Equation (26), the water produced by the system can be determined explicitly in terms of prescribed operating conditions.
Measurements of velocity profile in developing liquid flows
Authors: Atkinson Bernard , Kemblowski Zdzislaw , Smith J. M. 
Published: June 2004

AbstractAn optical technique for the quantitative determination of point velocities in rapidly developing laminar flows of transparent liquids is useful as an experimental tool in problems of complex geometries and fluids. The accuracy of the technique has been confirmed by comparison of experimental data with the numerical solution of the equation of motion for the entrance region problem. A distributor capable of generating a flat velocity profile has been developed for this purpose.