bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of reduction of iron oxide with carbon monoxide and hydrogen
Authors: Kawasaki Edwin , Sanscrainte Jack , Walsh Thomas J. 
Published: June 2004

AbstractThis investigation was undertaken to determine the rate controlling step in the reduction of iron oxides with hydrogen and carbon monoxide. For the reduction of porous hematite pellets, and bars it was found that the reduction rate is controlled by the counterdiffusion of reactant gas and product gas between the reaction zone and the main gas stream.The reduction specimens were spheres ranging in size from 1.5‐ to 4.4‐cm. diameter and 5.1‐ by 7.6‐cm. bars either 0.69 or 1.24 cm. thick. They were prepared from electrolytic iron powder, partially oxidized in a rotary kiln. The final oxidation of the specimens to hematite was accomplished by firing them at 1,149°C. in an oxidizing atmosphere. The bulk density was 3.5 g./cc. The specific surface area was 0.08 sq.m./g. and the void faction was 0.31. The oxide specimens were reduced in streams of pure hydrogen or carbon monoxide at temperatures between 700° and 1,200°C. The reduction was followed by measuring the sample weight during the reaction. Reduction rates were studied at system pressures of 1 and 2 at.The samples reduced step by step, to magnetite, to wüstite, and finally to iron. A shell of reduction, clearly visible in sections of partially reduced specimens, moved concentrically into the core of the samples. Ahead of the receding interface the specimens were known to be pervious to the reactant gases. This led to the conclusion that the gas composition at the interface was in equilibrium with the oxide phases present.Except for the removal of the last portions of oxygen at the lower reduction temperatures, the course of the reduction followed Fick's first law of diffusion. Values of the diffusion co‐efficients, determined from the experimental data, were in close agreement with values predicted from empirical equations. Varying the total pressure of the system had no effect on the rate of reduction, which is consistent with the equations developed from Fick's law for the diffusion‐controlled reaction under investigation.It is speculated that the retarding of the reduction reaction at the lower reduction temperatures is due to the entrapment of oxide inside shells of iron, which are impervious to the reducing gas. Reduction of the trapped oxide then proceeds by solid state diffusion in a manner proposed by Edström (6).
The viscosity of pure substances in the dense gaseous and liquid phases
Authors: Jossi John A. , Stiel Leonard I. , Thodos George 
Published: June 2004

AbstractViscosities available in the literature for the gaseous and liquid states of eleven substances have been correlated with reduced density by the use of dimensional analysis and the Abas‐zade expression for the residual viscosity to produce a single generalized relationship which is presented both graphically and analytically. The substances are argon, nitrogen, oxygen, carbon dioxide, sulfur dioxide, methane, ethane, propane,i‐butane,n‐butane, andn‐pentane. The properties required for the calculation of viscosity with this relationship are the molecular weight, the critical constants, and the density of the substance at the temperature and pressure considered.Separate relationships were developed for hydrogen, ammonia, and water which do not follow the consistent behaviour of the other substances. Viscosity values for ethylene calculated with the generalized relationship compared favorably with the corresponding experimental values.
A note on latent heat transport in nucleate boiling
Authors: Bankoff S. G. 
Published: June 2004

AbstractA simple one‐dimensional transport calculation is made which indicates that latent heat transport, by simultaneous evaporation and condensation at different portions of the bubble surfaces, can account for the major portion of the total heat flux in the neighborhood of the departure from subcooled nucleate boiling (burnout). This differs from the previously held view that the stirring action of the bubbles accounted for most of the heat flow in subcooled nucleate boiling. Other evidence is discussed which favors the latent heat transport theory.
The photochlorination of chloroform in continuous flow systems
Authors: Huff James E. , Walker Charles A. 
Published: June 2004

AbstractData on the vapor phase photochlorination of chloroform in flow reactors are interpreted on the basis of reaction mechanisms presented in the literature. In order to estimate the rates of light absorption it is also necessary to interpret the rate data obtained for the uranyl sulfateoxalic acid reaction.The chlorination results are represented quite well by a mechanism in which the most important termination step is a termolecular reaction between trichloromethyl radicals and chlorine. Deviations from this model are observed as the flow of reactants becomes turbulent and as the light intensity increases. The observed decrease in reaction rate under such conditions is attributed to the increased significance of a second termination step, the unimolecular deactivation of chlorine radicals at the reactor wall.
Thermal cracking of ethane and ethylene in a stock tube
Authors: Miller I. F. , Churchill S. W. 
Published: June 2004

AbstractThe rates of decomposition of ethane and ethylene were measured at temperatures between 1,250° and 2,800°K. and pressures between 0.25 and 2.0 atm. by exposing the gases to high temperature during the interval between the arrival of a compression wave and a reflected rarefaction wave in a shock tube. As contrasted with cracking at lower temperatures the ethane apparently reacted to hydrogen, ethylene, and acetylene and the ethylere to hydrogen and acetylene with negligible side reactions or polymerization. The over‐all decomposition rates at high temperature fall off sharply from those extrapolated from low temperature, indicating a change in mechanism. Additions of air, oxygen, carbon monoxide, and chlorine in amounts up to 17% did not effect the rate constants significantly.
A unified vectorial approach to difference point methods in stagewise operations
Authors: Lemlich Robert , Leonard Ralph A. 
Published: June 2004

AbstractA fundamental unified approach from vectorial considerations is presented from which the usual rectangular and triangular difference point methods are derived as special cases. The approach is then extended to yield other difference point methods including some of higher order. Results are applicable to blending, distillation, extractio, foam fractionation, and other operations.
Measurement of instantaneous rates of mass transfer to a small sink on a wall
Authors: Reiss L. Philip , Hanratty Thomas J. 
Published: June 2004

AbstractA technique has been developed for measuring the average rate of transfer and the fluctuations in the rate of transfer at a small source or sink on a wall. The transfer area consists of a small polarized electrode mounted flush with the wall. An electrochemical redox reaction whose rate is limited by mass transfer is employed. The technique can be used to study the flow pattern in the vicinity of the wall. By measuring the mass transfer simultaneously to two wall electrodes at varying distances apart the extent of unsteady flows in the vicinity of the wall can be measured.
Fundamental aspects of rotating disk contactor performance
Authors: Strand C. P. , Olney R. B. , Ackerman G. H. 
Published: June 2004

AbstractThe principles used in analyzing the performance of rotating disk contactor liquid extraction columns are discussed. The behavior of a swarm of drops in the rotating field is found to be adequately represented in most respects by single‐drop dynamics, which leads to tested relations for countercurrent capacity, limiting drop holdup, axial diffusion of the continuous and dispersed phases, and point mass transfer coefficients that are independent of column size effects.
Power requirements of gas‐liquid agitated systems
Authors: Michel B. J. , Miller S. A. 
Published: June 2004

AbstractPower data for dispersion of air in liquids by means of a six‐bladed flat blade turbine are presented in the form of a logarithmic plot of actual power consumed against a function of speed, impeller diameter, gas flow rate, and impeller power characteristics. The data are those of Michel (7), Bimbenet (2), Sachs (12), and Oyama and Endoh (10).Turbines of from 3‐ to 8‐in. diameter were run in tanks of from 6.5‐ to 18‐in. diameter, with the D/T never exceeding 0.47. The fluids tested covered a density range of 0.8 to 1.65 g./ml. and a viscosity range of 0.9 to 100 centipoises.Data are also presented on dispersion of air in a 50% by volume batch of carbon tetrachloride in water and dispersion of air in a suspension of Alundum particles in water, and compared with data on water in a similar system.The qualitative effect of a surface active agent is demonstrated in a comparison of data for a 0.1% by weight mixture of Pluronic L‐62 in water with data for pure water with the same apparatus.
Mass transfer and effective interfacial areas in packed columns
Authors: Yoshida Fumitake , Koyanagi Tetsushi 
Published: June 2004

AbstractExperimental studies on the mass transfer rates were performed for three kinds of operations: vaporization of water into air; absorption of methanol vapor by water; and distillation of three binary mixtures, trichloroethylene‐toluene, ethanol‐water, and acetone‐water, by use of columns of the same diameter packed with 25‐ and 15‐mm. Raschig rings. Correlations are presented for the individual phase height of a transfer unit and also for the effective interfacial areas. The effective areas for a given packing vary depending on the kind of operation as well as on the liquid rate and surface tension. The effective interfacial area for vaporization is significantly larger than that for absorption. The effective area for distillation seems to be roughly the same as that for absorption, if correction is made for the effect of surface tension.
Heat transfer in beds of fine particles (heat transfer perpendicular to flow)
Authors: Willhite G. P. , Kunii Daizo , Smith J. M. 
Published: June 2004

AbstractEffective thermal conductivites were evaluated for beds of fine glass beads from experimental data on heat transfer perpendicular to the direction of fluid flow. Results were obtained for a bead size range of 29 to 940 μ and for carbon dioxide, nitrogen, helium, and a C7 hydrocarbon liquid.The results showed that over the range of flow rate studied 0 to 80 lb./(hr.sq.ft.), or modified Reynolds number from 0 to 6.6, there was no effect of flow on the conductivity. Hence the measured stagnant conductivity k°e also satisfactorily represented heat transfer for flowing conditions. In view of this result, methods of predicting the stagnant conductivity were re‐examined and a revised prediction method proposed. The equations are based upon a model which supposes energy to be transferred through a continuous fluid phase and through the solid particles by a solid‐fluid series mechanism. The equations are compared with the data available in the literature.
Diffusion in slurries and in non‐Newtonian fluids
Authors: Clough S. B. , Read H. E. , Metzner A. B. , Behn V. C. 
Published: June 2004

AbstractDiffusivities in slurries and in non‐Newtonian solutions are predicted by means of an extension of the general Eyring rate theory. The fluid is considered as consisting of a number of discrete regions, each with its own contribution to the overall diffusion process. This model overcomes the unrealistic effects of fluid viscosity predicted by the conventional (empirical) equations. Whereas diffusivities predicted by means of prior art correlations were as much as 230 times lower than the experimental values in the systems, the maximum error in diffusivities predicted with the equations developed in this work was about 40%.Experimental data are provided on two kinds of fluids: slurries and a polymer solution. Both were highly non‐Newtonian (flow behavior indexes as low at 0.15). Benzoic acid and β napthol were employed as the diffusing solutes. The principal limitation of the experimental data is that only aqueous systems were investigated.Much further experimental work will be required to provide a truly adequate test of the theory and to evaluate the several unknown parameters in sufficient detail to enable highly accurate predictions. Additionally the model used suggests a possible mechanism for increasing diffusion rates in these systems which is worthy of exploration. It may also be applied to an analysis and prediction of diffusion rates in viscous Newtonian fluids, for which no adequate method is presently available.
Void fraction distribution in beds of spheres
Authors: Benenati R. F. , Brosilow C. B. 
Published: June 2004

AbstractThe radial variation of void fraction within a packed bed of uniform spheres has been found to vary from unity at the wall to about 38% in the interior of large beds. The voidage distribution takes the form of a damped oscillatory wave with the oscillations damped out at about 4½ to 5 sphere diameters from the container wall. The distribution function is essentially independent of whether the container wall is concave or convex.Continuous surfaces within the bed are responsible for local voidage variations similar to those at the container wall.An improved experimental technique is described in detail. The results presented are for a number of cases with D/d varying from 2.6 to infinity, and for boundary walls which are concave and convex.
Transport characteristics of suspensions: Part VI. Minimum transport velocity for large particle size suspensions in round horizontal pipes
Authors: Thomas David G. 
Published: June 2004

AbstractThe minimum transport velocity (defined as the mean‐stream velocity required to prevent the accumulation of a layer of stationary or sliding particles on the bottom of a horizontal conduit) vas determined in a 1‐in. pipe for an aqueous suspension of glass beads using glass beads having mean diameters of 78 and 310 μ.The results of the present study were combined with prior pneumatic‐ and hydraulic‐transport data for air and water suspensions to give a unique minimum‐transport relation, valid for particles larger than the thickness of the laminar sublayer, that is for particles which are immersed in the buffer layer or which extend into the turbulent core when resting on the pipe wall. The correlation showed that the ratio of particle settling velocity to friction velocity at the minimum transport condition was a function of particle Reynolds number, pipe Reynolds number, and the relative density ratio of particle to fluid. The results of the correlation suggest that a single mechanism is responsible for the initiation of particle transport throughout the range of conditions covered. This mechanism may be identified with Bernoulli forces due to instantaneous velocity differences accompanying turbulent fluctuations and largely confined to the buffer layer.
The role of porosity in filtration: Part V. Porosity variation in filter cakes
Authors: Tiller F. M. , Cooper Harrison 
Published: June 2004

AbstractExpressions are derived in which local porosity in a filter cake is determined as a function of the distance through the cake. Under conditions where the superficial flow rate through the cake is constant and the medium pressure can be neglected, local porosity and the hydraulic pressure are functions of the fractional cake distance.
Low temperature ortho‐para hydrogen conversion‐kinetic studies
Authors: Wakao Noriaki , Selwood P. W. , Smith J. M. 
Published: June 2004

AbstractRate studies were carried out for the ortho‐para hydrogen conversion at liquid nitrogen temperature with a multiple‐impregnation nickel on aluminum oxide catalyst. Data were obtained at pressures up to 400 lb./sq. in. gauge over a range of flow rates for three catalysts of different pellet sizes.For the largest particle, ⅛‐in. cylinders, diffusion resistances were significant. Effectiveness factors were evaluated and found to be somewhat less that 0.5 for this relatively active catalyst. After the diffusion resistances were accounted for, the surface rate was correlated on the basis of a mechanism supposing molecular hyddrogen to be adsorbed on the surface. Separate evaluation of the catalyst for the hydrogen‐deuterium exchange reaction suggested that dissociation was not significant at liquid nitrogen temperature.
High temperature transport properties of gases; limitations of current calculating methods in the light of recent experimental data
Authors: Amdur I. 
Published: June 2004

AbstractRequirements for satisfactory calculation of high temperature transport properties are discussed, with special emphasis on the role of the intermolecular potential. The determination of appropriate pair potentials from scattering of high energy neutral beams is described, and potentials obtained from helium, neon, argon, krypton, and xenon, each scattered by its own gas, are tabulated. Similar potentials are given for helium scattered by argon, nitrogen, methane, monofluoromethane, difluoromethane, trifluoromethane, and tetrafluoromethane; neon by argon; argon by hydrogen and nitrogen; atomic hydrogen by helium and hydrogen; and atomic deuterium by deuterium gas. Average potentials derived from suitable combinations of these experimental potentials are given for the like‐particle systems of nitrogen, methane, monofluoromethane, difluoromethane, trifluoromethane, and tetrafluoromethane.Results of calculations which use suitable and unsuitable potential functions are shown in tabulated form for the coefficient of viscosity, the coefficient of self‐duffusion, and the isotopic reduced thermal diffusion ratio of argon and of nitrogen, and in graphical form for the coefficient of viscosity of xenon.
Solid‐liquid‐vapor phase behavior of the methane‐carbon dioxide system
Authors: Davis J. A. , Rodewald Newell , Kurata Fred 
Published: June 2004

AbstractThe phase behavior of the methane‐carbon dioxide system has been determined experimentally along the solid‐liquid‐vapor locus. Pressure‐temperature measurements were made along this locus from the triple point of carbon dioxide to −284°F. Compositions of the vapor phase along the solid‐liquid‐vapor locus were determined with sampling techniques over a composition range of 0.1 to 12% carbon dioxide. Liquid‐phase compositions were obtained from crystal‐point determinations on eleven methane‐carbon dioxide mixtures ranging from 0.16 to 20% carbon dioxide.With the pressure‐temperature for the solid‐liquid‐vapor locus as the termination locus of the dew and bubble data of Donnelly and Katz (2), consistent liquid‐ and vapor‐phase compositions were obtained over the remaining concentration range.Changes in the pressure‐temperature relationship of the solid‐liquid‐vapor locus caused by using a methane stock containing 0.56 mole % nitrogen are also reported.
Transfer functions of heat exchangers
Authors: Hsu James P. , Gilbert Nathan 
Published: June 2004

AbstractIn the course of research the authors have collected a number of transfer functions for various types of heat exchangers. For the convenience of analysis the heat exchangers may be classified into several basic types described in subsequent pages. In each case certain assumptions are made when one writes down the differential equations of the heat exchanger, which constitute the so‐called mathematical model of the exchanger. If a particular heat exchanger is being classified, it is important to know the nature of temperature variation and the relative directions of flow of the exchanging fluid streams. If the heat exchanger in question matches one of the types described, then the transfer functions listed may be used to obtain its theoretical frequency and transient responses.
The prediction of vapor‐liquid equilibrium constants for binary hydrocarbon systems in the critical region
Authors: Mehra Vinod S. , Thodos George 
Published: June 2004

AbstractA series of reduced state correlations for the prediction of equilibrium constants for the components of binary hydrocarbon systems have been developed utilizing experimental vapor‐liquid equilibrium data reported by Kay (7, 8, 9) for the enthane‐n‐heptane, ethane‐n‐butane, and n‐butane‐n‐hepane systems. Each correlation applies for a specific values of τ = Tbh/Tbl, the ratio of the normal boiling points of the two components. Plots of β/β° vs. TR covering the complete range of liquid compositions are presented for values of τ = 1.10, 1.20, 1.40, 1.60, 1.80, and 2.00. The term β° represents the reduced vapor pressure of the pure substance, while β is the ratio of the pseudo vapor pressure of this substance in the mixture, Kπ, to the critical pressure of the mixture.The correlations presented in this study reproduce the experimental data used in their development with an average deviation of 2.3% for forty‐eight points, with the experimental critical constants reported by Kay. The reliability of these correlations has been tested with the propane‐isopentane, methane‐ethane, and ethane‐cyclohexane systems which have τ values in the range included in this study and for which experimental critical constants are available. An average deviation of 5.1% was produced for thirty‐six points. In addition the systems methane‐propane, propane‐benzene, nitrogen‐oxygen, and carbon dioxide‐n‐butane were tested with calculated values for their critical constants and produced average deviations of 8.4, 8.2, 9.4, and 20%, respectively.
Reaction kinetics and adsorption equilibria in the vapor‐phase dehydration of ethanol
Authors: Kabel Robert L. , Johanson Lennart N. 
Published: June 2004

AbstractThis work is an experimental assessment of the Langmuir‐Hinshelwood model of heterogeneous catalysis. The vapor‐phase dehydration of ethanol to diethyl ether, as catalyzed by cation exchange resin in the acid form, was the reaction chosen for study.Initial reaction rate data, determined from the integral kinetic data obtained experimentally, allowed selection of the most suitable rate equation from among several plausible equations derived in accordance with the above model. The Langmuir equilibrium adsorption constants in the rate equation were compared with the corresponding constants determined directly from pure component studies in a static adsorption system. The adsorption constants determined for the three reacting components by these independent methods showed definite order‐of‐magnitude agreement. The adsorption studies also provided significant information about the nature of the catalytic site.The extent of agreement in the constants determined by these two independent approaches is considered to be evidence of the theoretical validity of this model. Additional interpretation of the adsorption and kinetic data via this model suggests that the ethanol dehydration reaction proceeds through the reaction of adjacently adsorbed ethanol molecules.
Radiant heat transfer in packed beds
Authors: Chen John C. , Churchill Stuart W. 
Published: June 2004

AbstractThe effective scattering and absorption cross sections were determined from measurements of radiant transmission through isothermal beds of glass, aluminum oxide, steel and silicon carbide spheres, cylinders, and irregular grains. The radiant conductivities were calculated from these cross sections. Back scattering was found to be the principal mechanism of attenuation for all of the packings. Absorption was a significant mechanism only for the silicon carbide grains. At 2,000°F. The radiant contribution to the total heat flux was estimated to vary from 35% for the silicon carbide packings to 85% for the glass packings.