bluuebunny/crossref_metadata_2025_split huggingface dataset:
General analytical solutions for first and second order, homogeneous, irreversible reactions, in ideal tubular reactors
Authors: Lo S. N. , Cholette A. 
Published: March 2009

AbstractThe two particular exponential integrals involved in the conventional solutions for ideal adiabatic tubular reactors are represented by a modified series for computation purposes. For arguments larger than ten in absolute value, the method of asymptotic expansion removes the inconveniences that may be encountered in the numerical evaluation of the solutions.The expressions obtained with the modified series are not restricted by zero heat of reaction as is the case with the conventional solutions.General solutions, easily amenable to computer evaluation, are presented for first and second order irreversible reactions, under adiabatic or isothermal conditions.
Precipitate flotation: A preliminary study of the underlying mechanism
Authors: Kalman K. S. , Ratcliff G. A. 
Published: March 2009

AbstractPrecipitate flotation has been investigated in a continuous steady‐state unit using magnesium hydroxide suspensions (con centration range 2‐28 × 10−4 g‐mole/l) and sodium dodecylbenzene sulphonate as surfactant (concentration range 1.5.10 × 10−5 g‐mole/l) at a pH of 11.75. Experimental results indicate essentially instantaneous equilibrium of the surfactant at the bubble‐liquid interface, and a substantial adsorption of surfactant on the metal hydroxide particles. The latter adsorption affects particle removal. Electron microscopy and photography have been employed to determine the sizes of the particles and bubbles respectively.A model is proposed based on collisions between the particles and the bubbles. It allows for the coverage of surfactant on the particles and the available area for particles to adsorb on the bubbles. Tests of the model with data from continuous operation show an average deviation from experiment of under 10%.
Volumetric behavior of the ethane‐hydrogen sulphide system
Authors: Tiwari K. K. , Robinson D. B. 
Published: March 2009

AbstractExperimental data are reported on the volumetric behavior of four mixtures of ethane and hydrogen sulphide containing 77.55, 63.52, 39.95, and 21.42% ethane in the temperature range from 50° to 125°C at pressures to about 5,000 psia. Compressibilities were fitted to the Benedict‐Webb‐Rubin equation of state for each mixture with an average deviation of 0.47%, although the variation of the coefficients with composition was not in accord with Benedict's mixing rules. Simultaneous evaluation of all coefficients other than γ using an equation of the form \documentclass{article}\pagestyle{empty}\begin{document}${\rm k}_{\rm m} = \sum\limits_{{\rm i} = 1}^{\rm N} {\sum\limits_{{\rm j} = 1}^{\rm N} {{\rm x}_{\rm i} \,\,{\rm x}_{\rm j} \,\,{\rm k}_{{\rm ij}} } } $\end{document} and the data from 639 experimental points gave an average deviation of 0.645% and a maximum of 5.61%.
A high pressure autocollimating refractometer for determining coexisting liquid and vapor phase densities
Authors: Besserer G. J. , Robinson D. B. 
Published: March 2009

AbstractA high pressure apparatus has been developed for measuring refractive indices and compositions of coexisting phases in vaporliquid equilibrium. The refractive index is determined by measuring the angle of minimum deviation of a 30° prism with an autocollimating telescope mounted on a precision rotary table. The composition is determined by chromatographic analysis.The refractive indices and compositions of the coexisting liquid and vapor phases in the carbon dioxide‐n‐butane system were obtained at 37.7°C and pressures up to 80 atm. The densities of the phases were calculated using the molar average refractivity and these compared favorably with previously published data obtained by direct volumetric measurements.
The silica gel‐water vapor sorption therm
Authors: Jury Stanley H. , Edwards Harold R. 
Published: March 2009

AbstractThe sorption isotherms for moist air and silica gel were determined at a total pressure of one atmosphere and 82, 100, 125, 150, 175 and 200°F. A small hysteresis effect was noted.The silica gel‐moist air system can best be described by either of two equations. The first is the distribution function description of the Polanyi characteristic curve. If the data are described by this equation the adsorption process can be explained in terms of Polanyi's potential theory. Alternately, the data may be described by a double Langmuir expression.
A simplified form of Holland's equations in the solution of multicolumn distillation systems
Authors: Billingsley D. S. 
Published: March 2009

AbstractWhen the Holland convergence acceleration scheme has been extended to multicolumn sustems as by Nartker, Srygley and Holland a second set of unknowns which they term “systemΘ's” is required. An alternate formulation is presented here in which the Holland equations for multicolumn systmes are expressed without the introduction of any unknowns beyond those previously used in formulating the Hollad equations for a single column. This formulation permits the existence and uniqueness of a positive solution to be established when and arbitrary number of units are arranged in a single recycle loop.Furthermore a numerical difficulty encountered with the procedure of Nartker, et al is discussed and a modification is presented which elimiates the difficulty.
Optimal control of linear and nonlinear systems by two‐level optimization
Authors: Robertson Grant E. , Hawkins David J. , Luus Rein 
Published: March 2009

AbstractThe decomposition of a system into simpler subsystems, followed by the optimization of the individual subsystems, and then co‐ordinating the subsystem optimal solutions to yield the optimal control policy for the original system, is considered. Lasdon's co‐ordination algorithm, in which the subsystems are regarded as being completely independent, is improved by including the interdependence of the adjacent subsystems. For linear systems with a quadratic performance index, this procedure yields the optimal control policy in a single iteration from an arbitrary initial guess of the decomposition parameters. For nonlinear systems, the method includes linearizing the state equations, the calculation of the optimal control for the linearized system, and the adjustment of the corresponding decomposition parameters of the original problem until convergence is achieved. For the optimization of a nonlinear continuous stirred tank reactor such a procedure requires considerably more computation time than the standard techniques, and the optimum policies are less accurate.
Residence time distributions of a series of laminar stages
Authors: Maymo Jaime Antonio 
Published: March 2009

AbstractThe Residence Time Distribution (RTD) of a series of j cylindrical (and “slit”) geometry vessels with laminar flow is analyzed. Fully transverse mixing at the points of connection between cells and no significant contribution of molecular diffusion to the mixing process are assumed. This model leads to a one‐parameter (j) family of RTD curves, which are more asymmetric and long tailed than those predicted by the “ideal back‐mix cells in series” and “axial dispersed plug flow” models.
The flow of “settling” slurries in tubes with internal spiral ribs
Authors: Charles M. E. , H‐S CHEH C. , H‐L. CHU L. 
Published: March 2009

AbstractThe secondary flows created by an internal spiral rib in an otherwise conventional smooth tube are illustrated by reference to the axial, and combined tangential and radial velocity components for a fluid flowing in a 2‐inch diameter tube containing a rib with a pitch‐to‐diameter ratio of 3The effect of such secondary flows on the transportability of “settling”(suspensions)was investigated by measuring pressure gradients for the flow of two sand/water slurries in a smooth 2‐inch tube and in 2‐inch diameter tubes with ribs of pitch‐to‐diameter ratio 5.15, 3.32 and 1.80. Average flow velocities ranged from 0.5 to 8 feet/sec. and delivered concentrations ranged from 5 to 18 per cent by volumeWhile the ribs were found to be a disadvantage at relatively high average mixture velocities because of increased pressure gradients, they were found to be advantageous at relatively low velocities, i.e. velocities less than the critical deposit velocity for flow in the smooth tube, in that the pressure gradients, for a given sand/water slurry with a given delivered concentration and average velocity, were lower in the ribbed tubes than in the smooth tube. Because of this, the power consumption per unit mass of solid transported was reduced by the presence of a rib. The optimum pitch‐to‐diameter ratio was estimated to be about 5Pressure gradients measured for one of the slurries with air added as a third phase showed the presence of air to be a definite disadvantage
Waste water treatment by solvent extraction
Authors: Kiezyk P. R. , Mackay D. 
Published: March 2009

AbstractA review is presented of the application of solvent extraction to the treatment of waste waters. Methods of extraction, solute‐solvent separation and water — solvent separation are described. Phenol removal, oily water treatment, desalination, metal recovery by “liquid ion exchange” and miscellaneous other applications are described/ Available economic data are discussed. Possible future applications are outlined and it is suggested that greatest potential is in the treatment of oily waste water and of relatively concentrated streams containing valuable or noxious materials
Experimental design for the determination of coefficients in coupled non‐symmetric first order systems: The multicomponent diaphragm cell
Authors: Kosanovich George , Cullinan Harry T. 
Published: March 2009

AbstractThe diaphragm cell method for experimentally determining multicomponent liquid diffusivities is optimized. An exact matrix solution of the coupled, non‐symmetric, first order, linear, differential equations which presents a slightly different viewpoint is given. Optimum experimental conditions are defined for ternary systems for both single determinations and multiples of a single determination. The methods used can be applied to any number of components
Diffusion of positive chlorine in macroreticular resins
Authors: Dewar Edgar J. , Wayman Morris 
Published: March 2009

AbstractThe diffusion of chlorine in macroreticular chlorine exchange resins was studied by measurement of: (1) experimental concentration‐distance profiles, and (2) overall effective diffusion coefficients D̄. The results were compared to demonstrate that the second method, although simpler, yielded useful results. The transfer mechanism was shown to be pore diffusion where chlorine first diffused into the resin through the pores before being absorbed into the resin around them. Pore diffusion models yielded pore diffusion coefficients Dp of 3.1 x 10‐5 to 7.5 x 10‐5 cm2/sec. The rate of absorption was controlled by coupled diffusion but the film resistance became negligible after a short time. Effective (D̄) and concentration‐dependent (Ds) diffusion coefficients in the solid phase were in the range of 10‐9 to 10‐ cm2/sec
A laser interferometric method for electron concentration measurements in stabilized plasmas
Authors: Meubus Paul , Fortin Marc 
Published: March 2009

AbstractThis work presents an interferometric means for measuring electron concentrations between 1012 and 1016 electrons per cm3 in a stabilized ionized medium and an Argon plasma is used to illustrate the method. The interferometer is a 100 mW He‐Ne laser emitting at 6,328 Å and 3.39 microns and a movable mirror is used to obtain the interferometric fringes required for calculation of the electron concenrations in the plasmaThe method uses the interesting feature of the He‐Ne laser that both emissions at 6,328 Å and 3.39 microns originate at the same upper level so that variations in the 3.39 microns emission modulate the visible light (6,328 Å) output. This property has been used by a number of authors for measurements on plasmas in transient conditions; this paper presents an application of the method for stabilized plasmas, thus broadening the field of application
Diffusion effects in catalytic gas oil cracking
Authors: Best D. A. , Pachovsky R. A. , Wojciechowski B. W. 
Published: March 2009

AbstractWojciechowski's four parameter model of catalyst decay is applied to conversion data for gas oil cracking over a diffusion limited catalyst. The parameters thus obtained are compared with those obtained previously for a diffusion free form of the same catalyst, cracking the same feed stock under identical experimental conditions. The comparison shows that the presence of diffusion affects not only the rate of catalytic cracking but also the rate of aging. It is also shown that the introduction of diffusion phenomena has no effect on the mechanism of aging. The presence of diffusion limitations however has the effect of making the feed stock appear more homogeneous in reactivity
Prediction of excess free energies of liquid mixtures by an analytical group solution model
Authors: Ronc M. , Ratcliff G. A. 
Published: March 2009

AbstractThe group solution model of Ratcliff and Chao for the excess free energies of liquid mixtures has been put in analytical form using the Wilson equation. This procedure obviates some of the limitations and inaccuracies of the previous model, and is well suited to computer calculation. It was tested and found satisfactory for a wide range of mixtures containing the groups methylene and hydroxylGroup Wilson parameters were generated from experimental data for methylene/hydroxyl mixtures at 25°C to 95°C, and are given by

At temperatures within or close to this range, these parameters allow the prediction of excess free energies of binary or multicomponent mixtures containing these two groups. No experimental data are required. Good results are obtained for aqueous systems.
Fluid dynamics and flow patterns in stirred tanks with a turbine impeller
Authors: Desouza Abel , Pike Ralph W. 
Published: March 2009

AbstractVelocity profiles were measured in a stirred tank with a turbine impeller using a three‐dimensional, pitot tube probe. A tangential jet model was used to describe the flow in the region of the impeller, and two‐dimensional potential flow models and a circular jet were used to describe the flow in the rest of the tank. The tangential jet model accurately predicted the measurements from this work and comparable measurements reported in the literature for water and air, for varying impeller diameter and speeds and for different tank diameters. In the rest of the tank a three‐dimensional, low velocity, flow field exists; and the center of circulation is not a true stagnation point. The flow at this point is tangential. The two‐dimensional models only qualitatively described the flow in this region, and a three‐dimensional model would be required. It was experimentally and theoretically confirmed that standard practice of using 10% baffles effectively controls the flow in the tank.
Étude en régime non laminaire du mouvement d'une goutte dans un milieu pulsé
Authors: Chonowski A. , Angelino H. 
Published: March 2009

AbstractIn the first part of the work, the authors have experimentally studied the fall rate of single drops of chlorobenzene with different diameters into a water column subjected to strictly sinusoidal pulsations. It has been shown that there is always a retarding effect and that, in certain cases, the average speed in a pulsated medium may be much lower than the one measured in a motionless medium.In the second part of the work, the authors have made a theoretical analysis of the motion of a drop in a pulsated medium. An equation is suggested for describing that motion, which results from the analysis of the forces in which the drag coefficient is modified in order to take into account the dynamic effects. The aforesaid equation has been systematically solved by means of analog and digital computers and the results, which have been compared with the experimental data, agreed very well with the latter, the deviation being less than 1.18%.
Fall of drops in non‐newtonian media
Authors: Mohan V. , Nagarajan R. , Venkateswarlu D. 
Published: March 2009

AbstractTerminal velocities of drops of organic liquids of diameter 0.0726 to 0.7256 cm in polymer solutions are determined. The Reynolds number range covered is 0.1 to 103. Visual observations on the shapes and oscillations of drops are reported. A correlation for the terminal velocity data is presented.
Heat transfer from a horizontal tube to a fluidized bed in the presence of unheated tubes
Authors: Lese H. K. , Kermode R. I. 
Published: March 2009

AbstractAn experimental study of heat transfer from a horizontal tube to a fluidized bed was carried out in the presence of nearby unheated tubes. The effect of the number of tubes, their size, configuration, and the type of fluidized materials was studied. Certain configurations caused as much as a 56% reduction in heat transfer over the most favorable case. The top of the tube was covered by stagnant solids, the bottom partially by a gas film, and the sides by a small region of vigorously agitated solids. Most of the heat transfer occurred in the side region. An overall heat transfer coefficient of 35 Btu/hr‐ft2‐°F. was found at the best conditions.
Mass transfer from a single gas bubble
Authors: Weller K. R. 
Published: March 2009

AbstractGases covering a wide solubility range were used to measure absorption rates from single bubbles rising freely in water. Absorption rates were not sensitive to any power of the diffusion coefficient and solubility alone proved to be an adequate correlating parameter.Experiments with bubbles containing inert and soluble gas mixtures yielded no evidence for a gas‐film resistance, confirming published theory.Results for the absorption of CO2 by NaOH solutions correlated well with the theory for pseudo‐first‐order fast reactions, provided allowance was made for a decreasing “physical” solubility of CO2 with increasing ionic strength of the solutions.
Effect of channeling on the performance of adiabatic flow tank reactors for exothermic reactions
Authors: Lo S. N. , Cholette A. 
Published: March 2009

AbstractThe performance of CSTR's can be affected significantly by the presence of channeling, for irreversible exothermic first and second order reactions, under adiabatic conditions. Theoretical curves exhibit the variation of the conversion with residence time, for different channeling intensities and various values of the kinetic parameters. A certain degree of channeling can be greatly beneficial to the reactor performance, especially when the activation energy and heat of reaction are high, where multiple steady states can exist. For second order reactions, the ratio of the initial concentrations of A and B, considered as a parameter, plays a role similar to that of the kinetic parameters.
Experimental study on the optimum performance of an adiabatic MT reactor
Authors: Lo S. N. , Cholette A. 
Published: March 2009

AbstractThe performance of an adiabatic MT reactor has been studied under various experimental conditions, using the reaction between hydrogen peroxide and sodium thiosulphate. Following the M‐section, consisting of a CSTR, the T‐section was made up of a large number of small stirred tanks in series.The same general condition for optimizing the MT model, that the reaction rate in the M‐section be a maximum, is shown to apply when maximizing the conversion for a given residence time as it was shown previously to apply when minimizing the residence time for a given conversion.Very good agreement is shown between theoretical and experimental results, confirming the superior results often obtained with an MT combination as compared with those given by a stirred tank or a tubular reactor under similar conditions. Bi‐stable steady states of conversion have been achieved and their effect shown on the performance of the combined reactor.
The mechanism of the adsorption of alkyl xanthate species on galena
Authors: Wells P. F. , Nagy E. , Cleave A. B. Van 
Published: March 2009

AbstractOxidation of galena produced thiosulphate and sulphate ions at the mineral surface but flotation activity, using isopropyl xanthate as collector, was found to depend on the concentration of thiosulphate ions at the surface. It is proposed that the thiosulphate ion reacts with di‐isopropyl dixanthogen formed by oxidation of xanthate ion in solution. It was demonstrated that these species react in homogeneous solution to give xanthate and xanthogen‐thiosulphate ions. The proposed surface reaction may account for the formation of a layer of adsorbed xanthate ions and for the surface redox potential being raised to a value where more xanthate ions can be chemisorbed and where dixanthogen is stable.
Theory of diffusion of gases in protein solutions
Authors: Jalan V. M. , Tham M. K. , Gubbins K. E. 
Published: March 2009

AbstractA theory based on a rigid sphere model is presented for the diffusion coefficient of dissolved gases (and liquids) in protein solutions. The only quantities needed in order to make calculations are the rigid sphere diameters and the solution density; methods are given for obtaining the diameters.The theory predicts that the ratio of the diffusion coefficient of the gas in protein solution to that in pure water is strongly dependent on the size of the protein molecule, but is insensitive to the properties of the solute gas. The theory gives good agreement with available experimental data for the effects of protein concentration and molecular properties on the diffusion coefficient.
On the theory of dynamic plug‐flow processes: Inlet control and distributed trajectory control
Authors: Bailey J. E. 
Published: March 2009

AbstractTopological methods are applied in a study of the periodic operation of plug‐flow processes. Attention is focused on periodic processes, but the results are shown to apply to other important situations. Three combinations of control options are considered and compared. Attainable sets for each case are characterized. The theory describes comparisons between steady state and time‐varying controls and the à priori structure of optimal control.
Diffusion of binary organic liquid mixtures across polyethylene
Authors: Tombalakian A. S. , Markarian G. K. 
Published: March 2009

AbstractA study of the diffusion of binary organic liquid mixtures across a polyethylene membrane, induced by pressure and chemical potentials, has been made. The volume flows have been interpreted using the theory of irreversible thermodynamics in terms of a linear phenomenological equation. This relationship has been used to estimate the magnitudes of the phenomenological coefficients for volume flow across the membrane. The reflection coefficient, which is a measure of the membrane selectivity, has been evaluated for the various interdiffusing species. The dependence of the phenomenological and reflection coefficients on temperature for the various binary organic liquid systems has been determined.
Effectiveness factors for immobilized‐enzyme reactions
Authors: Moo‐Young M. , Kobayashi Takeshi 
Published: March 2009

AbstractThe effect of intraparticle diffusion in artificial membranes on the kinetic behavior of immobilized enzymes has been considered theoretically in terms of an effectiveness factor. When the immobilized enxymes obey a Michaelis‐Menten relationship, an approximate equation is proposed for the effectiveness factor. For a substrate inhibited enzymatic reaction, the effectiveness factor may exceed unity and display multiple steady‐state behavior. Thus, the over‐all rate of reaction in the artificial membrane is faster in this case than that when the substrate concentration in the interior is at the same as that at the exterior surface. In the case of a product inhibited enzymatic reaction, the effectiveness factor is always less than that which corresponds to a Michaelis‐Menten relationship.