bluuebunny/crossref_metadata_2025_split huggingface dataset:
ChemInform Abstract: Supported Metal Nanoparticles on Porous Materials. Methods and Applications
Authors: White Robin J. , Luque Rafael , Budarin Vitality L. , Clarke James H. , Macquarrie Duncan J. 
Published: March 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Convective diffusion in a parallel plate duct with one catalytic wall — Laminar Flow — First order reaction part I — Analytical
Authors: Gidaspow Dimitri 
Published: March 2009

AbstractCHARLES W. SOLBRIGThe problem of convective diffusion with a first order reaction on one wall of a catalytic reactor is solved to implement the determination of rate constants from overall conversion measurements. The analysis applies to an isothermal gas mixture with constant physical properties and a parabolic velocity profile. A complete separation of variables, an entrance region, and a fully developed solution as well as asymptotic expressions for large eigenvalues are presented.A formula is given which expresses the Nusselt number as a function of the rate constants. These quantities combine as additive resistances to form an effective rate constant. By analogy, one could apply these results to a plate heat exchanger with a finite wall resistance.
Convective diffusion in a parallel plate duct with one catalytic wall—laminar flow—first order reaction: Part II: Experimental
Authors: Kvlacki Francis A. , Gidaspow Dmitri 
Published: March 2009

AbstractThe catalytic reaction rate of combustion of hydrogen in air on platinized alumina was measured in a flat rectangular flow reactor with one catalytic wall in laminar flow. Since the rate of reaction is very high, this measurement normally must be made in turbulent flow. However, with the aid of the measured concentration profiles and the analysis presented in Part I, it was possible to ascertain the reaction rate in the laminar flow regime. The rate constants compare well with literature values which were measured in the turbulent flow regime. Average Nusselt numbers for mass transfer calculated for the diffusionally limited cases were in good agreement with those obtained from Part I.A narrow rectangular channel (aspect ratio = 8:1) with 16‐in. of one wall comprising the reactive section was constructed for this investigation. The channel has a long preheat section, an adiabatic section with multiple heaters, and thermocouples for maintaining isothermal conditions. Two micrometer mounted probes are inserted through the wall opposite the replaceable catalytic section. Concentrations are measured at the inlet, inside the reactive section, and at the outlet in a mixing chamber.
Interphase mass transfer in binary liquid systems — Laminar liquid jets
Authors: Fosberg T. M. , Heideger W. J. 
Published: March 2009

AbstractInterphase mass transfer was investigated in binary liquid systems using the laminar jet technique. A mathematical model of the mass transfer process was developed and appropriate experimental measurements were made in the cyclohexanol‐water, isobutanol‐water and ethyl acetate‐water systems. Good correspondence was obtained between predicted and measured mass transfer rates, which was taken to validate the use of the model. In particular the results indicated that, within the limits of experimental accuracy, interfacial equilibrium prevails in these systems for contact times on the order of one‐half second.
Gas mixing in fluidized beds containing screen packings
Authors: Chen B. H. , Osberg G. L. 
Published: March 2009

AbstractGas mixing was studied in a fluidized bed containing hollow, open‐wall packings using a continuous injection of oxygen as a tracer.During bed expansion, the reciprocal of mixing length, u/E1, for a gas‐fiuidized bed containing packings of dimension less than 3‐in. was found to decrease and then increase with the expansion ratio, Δ, passing through a minimum, in contrast to an unpacked fluidized bed for which no minimum u/E1, was reported.The minimum u/E1, occurred always at Δ = 0.30, independent of column diameter, of the shape or of the size of the packing, and of the size of the fluidizing particle. Values of the minimum u/E1's for a fluidized bed packed with various screen cylinders depended upon the size of the packing, dn, and of the fluidized particle, d1,. An empirical correlation of (u/E1)mn, with d1, and dn is presented.
Selective extraction of potassium chloride from saskatchewan sylvinite ore
Authors: Taylor J. B. , Hunt M. R. , Despault G. J. , Agyako A. H. 
Published: March 2009

AbstractThe distribution of potassium chloride in Saskatchewan sylvinite ore samples has been investigated using autoradiography. Saturated or nearly saturated aqueous solutions of sodium chloride have been used in an attempt to selectively leach out the potassium chloride from the ore. Selective leaching can only be achieved in ores having a contiguous association of potassium chloride crystals. Ores richer than 30% potassium chloride can be expected to fulfil this condition. Accompanying the dissolution of potassium chloride is a simultaneous recrystallization of sodium chloride which accumulates on the dissolving face of the potassium chloride and prevents further extraction. Trace amounts ofPb2+orMn2+ions prevent the accumulation of recrystallized sodium chloride and ensure that the dissolution of potassium chloride proceeds to completion. ThePb2+ion severely retards the dissolution of both sodium and potassium chlorides.Mn2+ion has little or no effect on the kinetics of the dissolution process and is accordingly the preferred additive.
Wall to fluid heat transfer in liquid fluidised beds: Part 2
Authors: Asmund B. W , Smith J. W. 
Published: March 2009

AbstractWall to fluid heat transfer coefficients and radial temperature profiles have been obtained for beds of hydrodynamically similar spheres fluidized with water in a 2.058 inch pipe at a constant heat flux. From packed bed to open pipe conditions, heat transport occurs mainly by turbulent mixing, although conduction through the particles and possibly particle convection have some effect at low porosities. This result contradicts a previously published prediction based on model calculations using erroneous temperature profiles(24). The model predicts a minor role for particle convection when appropriate temperature profiles are used.A series model based on the observed shift of thermal resistance from the wall region to the bulk of the bed with decreasing porosity is used to correlate heat transfer coefficients. The shift in resistance largely accounts for the maximum in heat transfer coefficient plots.
The unsteady state absorption of oxygen in cumene
Authors: Low David I. R. 
Published: March 2009

AbstractNew data are reported for the absorption of single bubbles of oxygen less than 5 mm in diameter in cumene at room temperature. Measured rates are compared with the theoretically predicted rates, based on new values of the diffusivity and solubility of oxygen in cumene, for absorption from spheres in potential flow and from rigid spheres. In the presence of the peroxide, which is a reaction product, absorption rates are high initially but decay after 15 seconds or so to a value expected for rigid spheres. The results are explained in terms of the accumulation of surfactant at the bubble surface.Preliminary measurements of the dissolution of carbon dioxide bubbles in water in the same apparatus gave results similar to other determinations reported in the literature.
Pumping capacities in stirred tanks theory and application
Authors: Cooper R. G. , Wolf D. 
Published: March 2009

AbstractThe pumping capacities for the propeller and turbine type impellers were derived analytically. The velocity and angle profiles along the blade width of a turbine impeller were also obtained.The applications of the pumping capacities in the simulation of a stirred tank reactor, in the derivation of the power consumption and intensity of segregation, and in the correlation of the heat transfer in a stirred tank, have beer given.
Computational methods in process optimisation: II. Variable recycle ratio or reactor length with bounded control
Authors: Paynter J. D. , Bankoff S. G. 
Published: March 2009

AbstractThe work of Part I on the optimal design of a tubular reactor, in which a second‐order reversible exothermic reaction is being conducted, with recycle of unconverted reactant, is here extended to the cases where either the residence time (reactor length) or the recycle ratio is not specified in advance. Bounds are imposed on the control variable, which is here the local heat transfer conductance from the cooling jacket to the reactor. A gradient technique in control space, accompanied by a search for the optimal switch points, was again effective. With this combined technique singular control arcs were located by the appearance of rapid oscillations of the switching variable.
Air flow in a tube with a diverging inlet: I. Development of the turbulent velocity profile
Authors: Lana I. G. Dalla , Christiansen S. E. 
Published: March 2009

AbstractThe results from an experimental study of the development of air velocity profiles in a vertical 6.25‐in. I. D., 28.5‐ft. long aluminum tube with a diverging conical entrance are reported. Using the axial development of centerline velocity as a starting‐length criterion, a maximum and asymptotic value was approached at 40 diameters from the tube entrance. The starting length was found to increase with increasing Reynolds number. The large center‐line velocity associated with the jetting of air from a 1‐in. I. D. tube into the diverging conical entrance enabled a more rapid development of the velocity profile than for the well known case of a converging rounded entrance. A limited comparison of undeveloped and fully developed velocity profiles in the turbulent core region of the 6.25‐in. tube was also made over Reynolds numbers from 9,000 to 55,000.
Kinetics of catalytic oxidation of methane: Application of initial rate technique for mechanism determination
Authors: Ahuja O. P. , Mathur G. P. 
Published: March 2009

AbstractA kinetic investigation on the oxidation of methane using a palladium catalyst was conducted. Conversions of methane were small and limited to about 10% to facilitate the use of initial rate approach. Plots of initial rate against total pressure and varying feed composition were used to interpret the data qualitatively. Regression coefficients from linearized rate equations and criteria of best fit were used to arrive at a plausible mechanism. The experimental results indicated that the reaction rate is controlled by surface reaction in which the adsorbed oxygen and adsorbed methane react to produce adsorbed carbon dioxide and adsorbed water.
Prediction of multicomponent diffusion coefficients
Authors: Cullinan Harry T. 
Published: March 2009

AbstractA predictive theory based on the modified absolute rate theory is extended to the prediction of diffusion coefficients in the concentrated regions of multicomponent liquid systems without the use of adjustable parameters. A scheme for the direct prediction of multicomponent diffusion coefficients in non‐associated liquid systems is presented, analysed and tested with available data.
Laminar flow in regular polygonal shaped ducts with circular centered cores
Authors: Ratkowsky D. A. , Epstein Norman 
Published: March 2009

AbstractThe method of least‐squares fitting of harmonic functions to known boundary conditions has been employed to obtain closed‐form solutions for laminar flow of an incompressible fluid through the constant area annulus between a regular polygonal duct and a centered circular core. The product of Fanning friction factor and Reynolds number has been determined for the entire range between the extreme case of no core and the other extreme case where the core touches the outerwalls. For the latter case, it is shown that when the number of sides of the polygon approaches infinity, f.Re approaches a minimum value of 6.22. The analysis of this case is further extended to corner angles less than 60°, the minimum imposed by an equilateral triangular duct.
The Simulation of Single Phase Tubular Reactors with Incomplete Reactant Mixing
Authors: Harris I. J. , Srivastava R. D. 
Published: March 2009

AbstractThe influence of reactant segregation and of the rate of reactant mixing on fast homogeneous chemical reaction rates is considered and a computer model presented to simulate the effect of mixing within a tubular reactor fed by two segregated but miscible streams.Results obtained from use of the model are discussed.
The effect of particle size distribution on packing density
Authors: Sohn H. Y. , Moreland C. 
Published: March 2009

AbstractThe packing density of a multi‐particle system is found to increase if the particle size distribution is extended. Results are reported for Gaussian and log‐normal size distributions using dense random packing of two sands with particle sizes of front <0.07 to 8.0 mm.Packing density is shown to be a function only of size distribution represented by a dimensionless standard deviation, and of particle shape. It is independent of particle size.Packing densities of binary mixtures of continuously distributed systems are found to depend upon the composition of the mixture, the mean‐size ratio of the components of the binary, and upon the packing density of the individual components. Maxima occur at compositions of 55 to 75% larger component, and increasing mean‐size ratios result in greater packing densities.The “increase in packing density” factor is a useful function for comparing, and setting limits to, packing densities of binary mixtures.The results should allow improved prediction and control of packing densities of many commonly encountered particle systems.
Velocity, subcooling and surface effects in the departure from nucleate boiling of organic binaries
Authors: Andrews D. G. , Hooper F. C. , Butt P. 
Published: March 2009

AbstractThe forced‐convection loop at the University of Toronto was used to determine DNB heat fluxes for the full range of variation in composition of the binary systems acetone‐toluene and benzene‐toluene, over the velocity range 1.09‐4.36 metre/sec. and the subcooling range 10‐50°C. Special attention was given to the precise location of the DNB point relative to the maximum (critical) heat flux.The variation of the DNB heat flux with composition was found to be complex, but an empirical graphical correlation was obtained for each system, correlating DNB heal flux with composition, velocity and subcooling.A limited study of the effect of degree of surface roughness pointed towards an effect on DNB which varied with the degree of subcooling, but which was independent of the coolant velocity.
Liquid hold‐up and minimum fluidization velocity in a turbulent contactor
Authors: Chen B. H. , Douglas W. J. M. 
Published: March 2009

AbstractTransient‐response experiments have been performed in conjunction with bed expansion measurements to determine liquid hold‐ups and minimum fluidization velocities in a 12‐in. turbulent‐bed gas‐liquid contactor. The amount of liquid hold‐up was found to be independent of gas velocity, but dependent upon both liquid rate and packing diameter in the same manner as reported for conventional fixed‐bed absorbers. The data on minimum fluidization velocity, Gmf, which was interpreted in the present study as the maximum gas mass velocity at which the bed maintained its static height, showed a considerable variation with packing diameter, dp and liquid flow rate, L. A correlation of Gmf with dp and L was presented.
Problems in modelling and the study of electrochemical reactor dynamics
Authors: Babajide A. B. , Fahidy T. Z. 
Published: March 2009

AbstractProper understanding of the unsteady state behavior (start‐up, shut‐down, process perturbation effects, etc. …) of electro‐chemical reactors requires realistic mathematical modelling. Inexact current knowledge of all thermodynamic, hydrodynamic and kinetic aspects of electrochemical systems, in addition to inherent mathematical complexities requires approximations to allow the characterization of such systems via control engineering principles. The usefulness of the process dynamics approach is illustrated by practical examples.
Calculating complex chemical equilibria by an improved reaction‐adjustment method
Authors: Smith W. R. , Missen R. W. 
Published: March 2009

AbstractImprovements in calculating complex chemical equilibria have been obtained (1) by incorporating a convergence‐forcer into the Cruise‐Villars method (a reaction‐adjustment method), and (2) by using a linear programming scheme to obtain an initial estimate of the equilibrium composition. Calculations on 50 problems show that the improved method is faster than the RAND method similarly modified (one that does not use stoichiometric equations).
Densities of hydrocarbons in their saturated vapor and liquid states
Authors: Bradford Michael L. , Thodos George 
Published: March 2009

AbstractThe Sum and differences of the saturated vapor and liquid densities of 23 hydrocarbons were used to develop the following reduced density relationships for these saturated statesThe hydrocarbons considered included n‐parafins, olefins, diolefins, naphthenes, and aromatics. Constants β, γ, and δ, and exponentnwere found to be dependent on,. Equation (a) can reproduce liquid densities with an overall average deviation of 1.1 % over the entire temperature range, while Equation (b) was found to apply only in the interval 0.900 ≤TR≤ 1.00 with an average deviation of 2.2%.For temperatures ofTk< 0.90, the saturated vapor density was found to depend on temperature as followswherekandmwere also found to beZcdependent. Values calculated using Equation (c), when compared with 81 available experimental densities for 12 hydrocarbons, produced an average deviation of 3.0%.
Chlorine exchange resins
Authors: Wayman M. , Salamat H. , Dewar E. J. 
Published: March 2009

AbstractThe authors have prepared high polymers which contain a labile chlorine atom. The active group in these polymers is the >NH or —NH2 group, which takes up chlorine from a chlorine‐rich environment, and in the chlorinated form gives up chlorine to an environment deficient in chlorine, for example which exhibits a chlorine demand. The resins, which may be natural or synthetic, act as an agent for chlorine transfer to or from a medium. The results of a preliminary investigation of the utility of various polyamides and amino resins are given. Mass transfer rate studies of chlorine uptake by a urea‐melamine‐formaldehyde resin and of chlorine liberation from a chlorinated resin of the same type, the effect of pH on these rates, and the practical maximum chlorine capacities are presented. The stability of chlorinated resins is described.
The effect of surface active agents on sorption isotherms of a model food system
Authors: Labuza Theodore P. , Rvtman Max 
Published: March 2009

AbstractThe extent of the capillary condensation phenomenon in the sorption of water by a model food system was studied. The system, composed of microcrystalline cellulose, a hydrocarbon oil, and water, was treated with non‐ionic surface active agents at various concentrations. Desorption and adsorption isotherms were made for triplicate control and treated systems at 37°c., using a desiccator method.During desorption, the surfactants increased the water equilibrium vapor pressure of the model system for all moisture contents, but with adsorption, this effect was observed only up to 50 to 60% RH. The magnitude of the hysteresis loop was diminished in all cases. These over‐all effects were due mainly to a lowering of the liquid surface tension of the water in the pores of the model. Capillarity was analyzed by the Kelvin Equation and existed down to 20% RH, which is close to the monolayer value for most models. In addition, data from low surfactant concentrations indicated that capillarity may extend even below the monolayer. The diminished hysteresis found in our experiments supports the “ink‐bottle” theory of hysteresis.
Geometric parameters for some flow channels
Authors: Tiu C. , Kozicki W. , Phung T. Q. 
Published: March 2009

AbstractA method was proposed earlier(1) for prediction of the average velocity or pressure drop in the flow of non‐ Newtonian fluids in conduits of arbitrary cross section. The method requires only a knowledge of two geometric parameters which characterize the flow geometry, and the fluid model equation. In this paper, evaluations of geometric parameters are presented for infinite and finite (enclosed)square and triangular arrays of cylinders, and for regular polygonal and star‐shaped conduits. With these parameters, predictions of the average velocity or related variables for the Zlow of any arbitrary non‐Newtonian fluid can now be made. Comparisons are made with recent analytical solutions and experimental data pertaining to non‐Newtonian flow in concentric annuli, and equilateral and right isosceles triangular ducts, which give additional support to the reliability of the proposed method.
An improved correlation for film boiling heat transfer on horizontal tubes
Authors: Sarma P. K. , Ravisankar G. , Apparao K. Venkata 
Published: March 2009

AbstractAn analysis of the distinct wave pattern of the vapor layer formation around a cylindrical heater element during film boiling yields a method to correlate the heat transfer coefficients in terms of the break‐off diameter of the bubble, frequency of the bubble emission, wave length (spacing of the bubbles) and other physical properties of the fluid.
Etude cinétique de la déshydrtation du sulfate de cuivre par thermogravimétrie et thermogradientimétrie
Authors: Kaliaguine Serge 
Published: March 2009

AbstractUne thernlobalance d'un type nouveau a été construite. Les déterminations de témperature sont faites par thermogradientimetrie. Un ereuset d'un type special permet de plus un contrhle précis de l'atmosphére au contact de 1′échnntillon. Des mesures cinétiques des trois déshydratations du sulfate de cuivre ont permis d'attribuer un ordre nu1 á ces trois réactions et de définir une énergie d'activation apparente isobare. Cette dernéhre grandeur a étć mesureée sous diverses pressions de vapeur d'eau.
Phase behavior of the methane‐carbon dioxide‐n‐butane and methane‐hydrogen sulphide‐n‐butane systems
Authors: Saxena A. C. , Robinson D. B. 
Published: March 2009

AbstractExperimental vapor‐liquid equilibrium data have been obtained for the methane‐hydrogen sulphide‐n‐butane and the methane‐carbon dioxide‐n‐butane systems at temperatures of −20°, 40° and 100°F. and at 400, 800 and 1200 psia pressure for each temperature. The data for the latter system show disagreement with the work of previous authors on this system at some of the conditions studied. The data were obtained using a variable volume cell with mercury as the confining fluid. A new type of internal valve was designed to provide a better means of establishing equilibrium between the liquid and vapor phases.The presence of hydrogen sulphide and carbon dioxide caused a two to three‐fold elevation in the hydrocarbon K‐values. Predictions of the vapor‐liquid equilibrium behavior for these systems utilizing the Chao‐Seader correlation and the Wilson equation were unsatisfactory. The K‐values for hydrogen sulphide and carbon dioxide obtained from the NGSMA Engineering Data Book differ up to 50% from the experimental K‐values.