bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extractive reaction: Batch‐ and continuous‐flow chemical‐reaction systems, concentrated case
Authors: Trambouze P. J. , Piret Edgar L. 
Published: June 2004

AbstractThe theory of extractive reaction is extended to concentrated solutions where the distribution coefficients are no longer constant and where important changes in phase volumes may occur. The methods developed are applicable to simple or complex reactions of any order. Two‐ and one‐solvent systems are treated, and convenient graphical methods are developed and illustrated with numerical examples.
The transition from free to forced convection in mass transfer from solid spheres
Authors: Garner F. H. , Hoffman J. M. 
Published: June 2004

AbstractMass transfer rates have been measured at 30°C. over a Reynolds number range of 1 to 130 for the solution of 3/8‐in. diameter spheres of benzoic acid for both upflow and downflow streams. These are compared with similar results for 3/4‐in. diameter spheres and show a gradual transition from forced to free convection. The interaction between the two effects is complex but less marked for the smaller spheres. Free convective effects do not disappear entirely until a Reynolds number of about 250 for the 3/8‐in. spheres, compared with a value of 750 given for 3/4‐in. spheres in the previous work (6).
Formation of interfacial area in immiscible liquids by orifice mixers
Authors: McDonough J. A. , Tomme W. J. , Holland C. D. 
Published: June 2004

AbstractThe interfacial areas formed in various immiscible liquid pairs by an orifice mixer were measured by a photoelectric method, which had been calibrated photographically. In addition to the variation of the liquid pair, total flow rate, volume fraction of the dispersed phase, and the orifice diameter, the pipe diameter of the mixing orifice was also varied. It was found that the formation of interfacial area could be correlated as a function of the change in kinetic energy across the mixing orifice, the energy required to overcome the viscous forces within the dispersed phase, and the volume fraction of the dispersed phase.
The effect of plate wetting characteristics on pulse column extraction efficiency
Authors: Sobotik R. H. , Himmelblau D. M. 
Published: June 2004

AbstractLiquid‐liquid extraction of acetic acid from the methyl isobutyl ketone‐water system was studied as a function of plate wetting characteristics and other variables in a pulsed perforated‐plate extraction column.Various combinations of stainless steel plates and polyethylene plates were used with different directions of solute transfer at a constant throughput of 82.6 lb. total flow/(min.) (sq. ft. column area) and with other operating variables in the following range:Frequency — 16 to 117.1 c./min.Amplitude — 0.492 and 0.973 in.W/K flow ratio — 0.46 to 2.8 lb. water/lb. ketoneThe plate wetting characteristics were found to affect the column extraction efficiency when the solute transfer was from the continuous ketone phase to water. An all polyethylene plate arrangement provided the best efficiency (H. T. U.oc = 4.1 in.) while an all stainless steel plate arrangement was less efficient (H. T. U.oc = 6.1 in.) under the most favorable operating conditions. A combination of these two arrangements in the column produced efficiencies midway between the all‐plastic plate arrangement and the all‐stainless steel plate arrangement.Within the column flooding limits the extraction efficiency did not seem to be affected by the plate wetting characteristics when the solute transfer was from water to the continuous ketone phase.
Characteristics of the mean flow patterns and structure of turbulence in spiral gas streams
Authors: Schowalter W. R. , Johnstone H. F. 
Published: June 2004

AbstractMeasurements were made of the flow structures in two types of spiral flow fields. The first was a vortex tube in which air entered one end of an 8‐in. pipe through an involute entry and left at the opposite end. The second was a conventional cyclone separator in which the same entry was used.The experimental results show that the mean and turbulent flow structures are not sensitive to changes in the flow rate, but they are greatly affected by the geometry of the system. In the vortex tube the angular velocity is nearly constant at radial distances less than one‐half of the radius of the pipe. The flow patterns in the vortex tube and in the cyclone are not symmetrical with the pipe axis. The asymmetry can be explained by postulating a dynamic center line with helical shape. The longitudinal intensity of turbulence increases sharply near the center of the vortex tube. This is caused primarily by the abrupt decrease in mean velocity near the center. The radial intensity also increases near the center, but near the wall it decreases rapidly with distance from the center. The longitudinal intensity of turbulence in the cyclone is highest near the center and near the wall. The high intensity near the wall is caused both by the decrease in mean velocity and the increase in root‐mean‐square turbulent velocity.
Measurement of concentration fluctuations with an electrical conductivity probe
Authors: Lamb D. E. , Manning F. S. , Wilhelm R. H. 
Published: June 2004

AbstractAn electrical conductivity probe capable of measuring liquid phase concentration fluctuations occurring at frequencies up to 8 kc. is described. The design permits concentration measurements in volume elements of the order of 3 × 10−5 cc. The probe was applied successfully to the measurement of turbulent concentration fluctuations.
Thermal transfer in turbulent gas streams: Temperature distribution in boundary flows about spheres
Authors: Bathish L. N. , Sage B. H. 
Published: June 2004

AbstractA knowledge of the temperature distribution about bodies of revolution, and more particularly about spheres, is of interest in connection with many problems associated with thermal and material transport. The present investigation involved measurements of the temperature distribution in the boundary flows about a 0.5‐in. porous sphere and 0.5‐in. and 1.0‐in. silver spheres. The measurements were made in an air stream at velocities between 4 and 32 ft./sec. under conditions of shear flow, as well as at various positions in the wake of a perforated grid. From these measurements the thickness of the thermal boundary layer was established as a function of polar angle and conditions of flow. The experimental data were correlated upon the assumption that the normalized temperature in the boundary flow is a single‐valued function of the position in the thermal boundary layer. It appeared that this simple assumption described the experimental data within the uncertainties of measurement and that the Blasius function provided a reasonable description of the relationship of the normalized temperature to the relative position in the thermal boundary layer.
Diffusion rates in porous catalysts
Authors: Henry J. P. , Chennakesavan Balapa , Smith J. M. 
Published: June 2004

AbstractRates of diffusion of helium, nitrogen, and carbon dioxide through alumina pellets were measured at atmospheric pressure and room temperature. The cylindrical pellets, ¾ in. diameter and ⅜ in. in length, were prepared from α‐alumina particles with a mean pore radius of 65 Å. Surface area and pore volume data indicated that the corresponding mean pore radius of the micro and macropores in the whole pellet was 96 Å.The results showed that Knudsen type of diffusion was the controlling transport process despite the large fraction of void volume in the macropores. Carbon dioxide diffused more rapidly than expected, suggesting the possibility of migration of physically adsorbed molecules along the pore walls.The diffusion rates were about 16% higher than predicted, with a mean pore radius (Wheeler model) based upon the void volume of both micro and macropores used. However there is no logical basis for using this mean pore radius for a pellet having widely separated, micro and macropore size distributions.
Boundary‐layer behavior on continuous solid surfaces: I. Boundary‐layer equations for two‐dimensional and axisymmetric flow
Authors: Sakiadis B. C. 
Published: June 2004

AbstractThis study deals with boundary‐layer flow on continuous solid surfaces. Flow of this type represents a new class of boundary‐layer problems, with solutions substantially different from those for boundary‐layer flow on surfaces of finite length. In this paper the boundary‐layer behavior on continuous surfaces is examined, and the basic differential and integral momentum equations of boundary‐layer theory are derived for such surfaces. In subsequent papers these equations will be solved for the boundary layer on a moving continuous flat surface and a moving continuous cylindrical surface, for both laminar and turbulent flow in the boundary layer.
Combined free and forced convection in a constant temperature horizontal tube
Authors: Jackson T. W. , Spurlock J. M. , Purdy K. R. 
Published: June 2004

AbstractAn experimental study of superposed free and forced convection for air in a horizontal tube is reported. The laminar Nusselt number, based on the log mean temperature difference, ranged from 29.9 to 15.2; the laminar flow Graetz number, based on the bulk or average temperature of the air, ranged from 33 to 1,300, the Grashof‐Prandtl modulus based on properties of air at the wall temperature ranged from 1.1 × 106to 2.2 × 106. The Grashof number utilized the log mean temperature difference. An analysis of the system from a macroscopic viewpoint led to the determination of an equation which fits the laminar flow experimental data in the range of Graetz numbers from 60 to 1,300. An equation was also found for the turbulent data.
Turbulent newtonian flow in annuli
Authors: Meter Donald M. , Byron Bird R. 
Published: June 2004

AbstractIn recent years there have been quite a few experimental studies on turbulent flow in annuli. In this paper a Prandtl mixing‐length approach is applied to give a friction factor vs. Reynolds number expression for annuli [see Equation (22) and Table 1]; this expression describes tube flow and slit flow as special cases. No new adjustable constants appear in the final result other than those determined earlier for tube flow. The final expression is found to predict friction factors within the accuracy of the existing experimental data. The mixing‐length friction‐factor expression is thus substantially more accurate than the usual hydraulic‐radius procedure and of comparable accuracy to other recent annulus friction‐factor treatments.
A modification of the momentum transport hypothesis
Authors: Gill William N. , Scher Marvin 
Published: June 2004

AbstractA continuous velocity distribution is derived which is based on an arbitrary modification of Prandtl's mixing length expression. The resulting velocity distribution agrees well with experiments for transition and fully developed turbulent flow throughout the entire cross section of the conduit. Furthermore the mixing length expression applies to parallel flow in smooth circular tubes and between infinite parallel plates with the same set of constants.
Simultaneous mass and heat transfer in the flow of gases past single spheres
Authors: Evnochides Spyros , Thodos George 
Published: June 2004

AbstractThe results obtained by the evaporation of water and nitrobenzene in air from celite spheres in conjunction with the prevailing surface temperature have permitted the simultaneous determination of mass and heat transfer factors. The spheres used were 1.42, 1.88, and 2.00 in. in diameter. The experimental results of this study show that an essentially direct correspondence exists for mass and heat transfer in the flow of fluids past single spheres.
Size distribution of droplets from centrifugal spray nozzles
Authors: Nelson Paul A. , Stevens William F. 
Published: June 2004

AbstractMethods for expressing, measuring, and correlating drop‐size distribution data for centrifugal spray nozzles are discussed.A method for collecting spray droplets in liquid nitrogen is described which is rapid and efficient for most sprayed liquids which freeze above —20°C. Comprehensive correlations for drop‐size distributions are reported based on 114 runs performed with the liquid nitogen method.
Tubular reactor sensitivity
Authors: Coste Joseph , Aris Rutherford , Amundson Neal R. 
Published: June 2004

AbstractThe empty lumped constant tubular reactor is considered for an incompressible fluid in which an arbitrary number of chemical reactions is occurring. It is assumed that the reactor influents are steady with time on the average but have superimposed upon them random fluctuations. If the random perturbations are infinitesimally small, the unsteady state equations are linear, the linearity following from the fact that any transient may be considered as a perturbation from the steady state. Thus the effluents are random functions whose mean and variance may be calculated with ease. Reactor sensitivity is defined as the ratio of the standard deviation of an output to the standard deviation of an input. The general theory is developed and two examples are worked to illustrate the method.
Phase and area contributions to mass transfer kinetics
Authors: Teller A. J. 
Published: June 2004

AbstractA relationship has been developed describing quantitatively the factors affecting packed column performance. The relationship, based on the Colburn equation, is proposed within the limits of a consistent flow regime in the liquid phase.Via separation of the effects of packing geometry on diffusion rates and the effect of area variation with flow rate, single phase transfer rates can be obtained from over‐all mass transfer data. The appearance of a maximum in the relationship ofHoGvs.Gin the range of 60% of flooding is explained by the large increase of the termHoG/ai(∂ai/∂Gm) relative to the term 1/ai(∂HGai/∂Gm). The ammonia‐air‐system behavior is analyzed via this relationship. It is found that the gas phase resistance varies between 72 and 94% of the over‐all resistance as a function of flow rate.
Design of experiments on the kinetics of the water‐gas shift reaction
Authors: Hulburt Hugh M. , Srini Vasan C. D. 
Published: June 2004

AbstractExperiments on the continuous catalytic water‐gas shift reaction have been carried out making full use of the principles of statistical design to elucidate the reaction mechanism. Instantaneous reaction rates were determined for sixteen different combinations of the five variables: partial pressures of carbon monoxide, hydrogen, carbon dioxide, and temperature. Nitrogen gas was used as an inert diluent to make up the total pressure to 1 atm. From the analysis of variance of these sixteen runs it can be shown that the Temkin mechanism for the water‐gas shift reaction cannot represent the data within the experimental accuracy. A tentative alternative mechanism which is consistent with the data obtained is presented. The work shows that while it is possible to obtain useful empirical kinetic data from small, well‐planned experiments, both highly precise experimental data and very careful statistical treatment are required. When these are available, a very marked reduction in the amount of experimental work can be effected.
The distribution of nitric acid between water and tributyl phosphate ‐ hexane solvents
Authors: Olander Donald R. , Donadieu Lucien , Benedict Manson 
Published: June 2004

AbstractThe distribution of nitric acid between water and solutions of tributyl phosphate in n‐hexane has been measured over a greater range of acid and tributylphosphate concentrations than have been reported previously.The partitioning of nitric acid between water and tributylphosphate‐hexane solvents has been satisfactorily explained on the basis of the commonly accepted equilibrium complexing reaction, with this modification: The over‐all aqueous‐to‐organic reaction is subdivided into the distribution of uncomplexed nitric acid and an organic phase complexing reaction. This alteration is found necessary to account for the behavior of the partitioning data of dilute acid over the entire tributylphosphate‐hexane range. The residual discrepancy between the theory and the data can be qualitatively attributed either to modest nonideality of the organic phase or to the effect of the varying water content of the solvent on the distribution coefficient of uncomplexed nitric acid.The sparse data on water extraction by tributylphosphate‐hexane solvents are not amenable to the same type of analysis, even though a type of complexing similar to that found for nitric acid has been previously proposed. The interaction between water and tributylphosphate appears to be stronger than that normally attributed to nonideality but weaker than a true chemical complex.
Further studies of fluid flow and mass transfer in trickle beds
Authors: Schiesser W. E. , Lapidus Leon 
Published: June 2004

AbstractResidence‐time studies are reported for water trickling down through a 4‐in. column packed with spheres. The transient response of the column to pulse‐ and step‐function inputs in tracer concentration applied to the water stream was determined for both porous and nonporous packing. Significant radial variations in the distribution of residence times and the volumetric rate of flow were observed. The contribution to the response curves of diffusion into the porous packing and flow in the interparticle voids can be separated. The diffusion rates may then be characterized in terms of an effective pore diffusivity for the packing.
Slow compression crushing of single particles of glass
Authors: Kenny William J. , Piret Edgar L. 
Published: June 2004

AbstractGlass cylinders and spheres were crushed by slow compression in a hydraulic press. In all experiments the elastic energy stored in the specimen prior to fracture was measured. In some experiments the surface area of the resultant powder was measured by gas adsorption; in others the heat generation upon fracture was measured. The latter experiments show that considerable additional energy is fed into the fracturing specimen from the press. Local stress concentrations, and hence energy level at fracture, varied widely with particle shape. Calorimetric experiments suggest that real differences in crushing effectiveness, that is new surface per unit actual work done on the specimen, do occur. These differences are not due directly to the magnitude of the energy fed in from the press but rather to the effectiveness with which the stored or feed‐in energy is used.
Two‐phase concurrent flow in packed beds
Authors: Larkins R. P. , White R. R. , Jeffrey D. W. 
Published: June 2004

AbstractPressure drop and liquid saturation accompanying two‐phase concurrent flow have been studied in a variety of packings and with gas‐liquid systems having a wide range of fluid properties. Two basic flow patterns were observed with nonfoaming systems. Correlations of pressuredrop and liquid‐saturation data were obtained in terms of the single‐phase friction losses for the liquid and the gas when each flows alone in the bed. Deviations from the correlation with foaming systems are discussed and illustrated with sample data.
Effectiveness factors for porous catalysts
Authors: Mingle J. O. , Smith J. M. 
Published: June 2004

AbstractFrom the equations expressing mass and energy transfer in the solid and void regions of a catalyst of micropores, conversion and temperature profiles are evaluated as a function of the properties of the particle and the reaction system. The method developed is illustrated with numerical calculations for a first‐order, irreversible reaction. Microeffectiveness factors Ec are derived from these profiles for several distribution functions for the size (radius) of the micropores.The results indicate that the nature of the pore‐size distribution cannot affect Ec more than about 10%. However effectiveness factors greater than unity are possible for exothermic reactions with high heats of reaction and particles of reasonable size.To treat pelletted catalysts, equations are also developed for determining conversion and temperature profiles in pellets formed by compressing the microporous particles These results are interpreted in terms of macroeffectiveness factors Es, with values of Ec applicable at various positions in the pellet. To illustrate the method of solution numerical values of Es are determined for a limited range of parameters. The results indicate that in pelletted catalysts large temperature gradients may exist. For an exothermic reaction this can lead to a significant increase in macroeffectiveness factor.
Membrane selectivity
Authors: Wills G. B. , Lightfoot E. N. 
Published: June 2004

AbstractPrevious investigators have developed general integrations of the Nernst‐Planck flux equations to predict the behavior of ion exchange membranes in forced diffusion cells. These results are also applicable to stagnant liquid films, since this latter case can be considered as a membrane with a vanishingly small concentration of fixed charges (1). However these general integrations yield results of considerable complexity, and even the analysis of a specific system becomes a problem of some scope. This paper is based upon a much less general integration which proceeds by a straightforward manipulation of the Nernst‐Planck flux equations for the special case of a single one‐to‐one electrolyte. The results are used to predict the behavior of a system consisting of a membrane with a stagnant film of liquid on either side. To further facilitate understanding the initial results are further simplified by assuming certain specific systems and then constructing plots showing the membrane efficiency in terms of readily interpreted, commonly encountered variables such as thicknesses, currents, and concentrations.
Heat transfer in reacting systems: Heat transfer to nitrogen dioxide gas under turbulent pipe flow conditions
Authors: Krieve Walter F. , Mason David M. 
Published: June 2004

AbstractHeat transfer rates of both heating and cooling for dissociating nitrogen dioxide gas were experimentally measured under turbulent pipe‐flow conditions. The range of the average Reynolds numbers for which these measurements were made was from 6,700 to 22,000. Thermal flux at the inside surfaces of the tubes ranged from 300 to 8,400 B.t.u./hr.‐sq. ft. for heating and cooling. Wall temperatures of the heater section were varied from 100° to 400°F. and those of the cooler section were varied from 70° to 140°F. Mixed mean bulk gas temperatures for both heating and cooling were in the range 72° to 190°F. Radial velocity and temperature profiles were measured at various longitudinal positions in the heater section.For this equilibrium gas mixture heat transfer coefficients as high as 14 times those for the gas under frozen equilibrium conditions were obtained. Correlations which should be generally applicable to equilibrium reacting systems have been determined from the experimental data.
Free entrainment behavior in sieve trays
Authors: Cheng S. I. , Teller A. J. 
Published: June 2004

AbstractAnalysis was made of the behavior of entrained particles in the zone between trays in a sieve tray column for the air‐water system. The effects of drop‐size distribution, projection velocity, drag, and gravity were evaluated with respect to the quantity of entrained liquid between trays. The drop‐size distribution was found to be logarithmic in nature.The entrainment as a function of distance above the froth is estimated in Equation (12) where dH may be calculated from projection velocities and column superficial velocity for particle sizes greater than 400 μ.Confirmation of the proposed entrainment equation via experimental data was achieved within an average deviation of 28%.It was anticipated from the relationships developed that a leveling off of entrainment at zones in proximity to the froth and at escape velocity heights would be observed. Confirmation was evident at zones in proximity of the froth and upper zone tendencies were observed.