bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of coal‐oil mixture sedimentation by modified continuity wave theory
Authors: Ekmann James M. , Klinzing George E. 
Published: March 2009

AbstractCoal‐oil mixtures which have the potential to stretch oil usages have been analyzed as to their sedimentation behavior by applying a modification of the continuity wave theory as developed by Kynch. Three coal‐oil systems have been studied and have been shown to follow the pseudo continuity wave theory by assigning a degree of agglomeration to the coal particles. With the presence of surfactants, the sedimentation of the mixtures could be similarly analyzed. The general effects of particle size of the coal and temperature of the system have been considered and presented as guidelines for design.
Flow characteristics of a laminar swirling impinging jet: A numerical study
Authors: Huang B. , Mujumdar A. S. , Douglas W. J. M. 
Published: March 2009

AbstractThe primitive Navier‐Stokes equations were solved to predict the flow field induced by a partially confined swirling laminar jet impinging normally on a flat surface. A study is made of the influence of the jet Reynolds number, nozzle‐to‐plate spacing, axial and swirl velocity profiles at nozzle exit plane, size of the confining and impingement plate and uniform suction applied at the plate. An interesting feature of the flow configuration is the predicted development of a recirculation bubble in the stagnation region which influences the heat and mass transfer characteristics. Axial and swirl velocity profiles at entry have dominant influence on the development of the flow field.
Intraparticle mass tranfer in weak acid ion‐exchanger
Authors: Kataoka Takeshi , Yoshida Hiroyuki 
Published: March 2009

AbstractResin phase mass transfer in a weak acid ion‐exchanger was analyzed based on a shrinking core model. It was assumed that H‐form core and metallic ion‐form shell appear in sorption of metallic ion, while metallic ion‐form core and H‐form shell appear in regeneration of metallic ion‐type resin. At the moving boundary, instantaneous irreversible reaction occurs, namely, neutralization reaction in the sorption and the protonation reaction in the regeneration. The Nernst‐Planck equation was applied to the fluxes of ions diffusing through the shell and the analytical solutions of sorption and regeneration rates were derived by assuming a pseudo‐steady state diffusion. Those solutions agreed fairly well with the experimental results in R‐H‐NaOH system (sorption) and in R‐Na‐HCl, R‐Cu‐HCl and R‐Cu‐H2SO4 systems (regeneration).
Gas‐liquid reactions in packed beds: The effectiveness of static hold‐up in presence of gas side resistance
Authors: Patwardhan V. S. 
Published: March 2009

AbstractThe interfacial area in a packed bed may be divided into two parts, i.e. the interfacial area corresponding to the dynamic hold‐up and that corresponding to the static hold‐up. The effectiveness of the latter for gas absorption with a chemical reaction can become quite low due to the depletion of the liquid phase reactant in the static hold‐up. As a result, the effective interfacial area may become substantially smaller. This aspect has been investigated earlier for liquid phase controlled absorption with a chemical reaction. In this paper, a procedure is developed for calculating the effectiveness of the interfacial area of the static hold‐up for the case of significant gas‐side mass transfer resistance for a second‐order chemical reaction. It is shown that the gas‐side mass transfer resistance increases the effectiveness of the static hold‐up. The results are presented in a convenient graphical form. It is shown that under certain conditions this effectiveness is quite sensitive to the magnitude of the gas‐side mass transfer resistance. The analysis presented here is based on the film theory.
Estimation of critical data by equation of state
Authors: Schmidt G. , Wenzel H. 
Published: March 2009

AbstractA recently proposed cubic equation of state was used to predict critical temperature Tc and pressure pc from liquid density at room temperature and from boiling temperatures generally at 13 kPa and 100 kPa. Calculated and experimental critical data are compared for some 270 substances. For non‐associating substances the values were generally found to be in close agreement. The method was then used to produce values of Tc, pc as well as acentric factors ω for nearly 1700 compounds. Comparative calculations were performed with Soave's as well as Peng and Robinson's equations and showed that application of these equations is restricted. Examples are given to show that the method may be extended to cover associating substances.
Analysis of fluidized bed catalytic cracking regenerator models in an industrial scale unit
Authors: De Lasa H. I. , Errazu A. , Barreiro E. , Solioz S. 
Published: March 2009

AbstractFluidized bed regenerator models, under steady state conditions, have been reconsidered because of recent significant changes in the technology of fluidized bed regenerators. Zeolitic catalysts, temperatures of the dense bed at about 700°C and lower CO/CO2 relationships are the new characteristics of the units.Following these innovations the operating conditions of the industrial catalytic cracking regenerator of Destileria La Plata, Yacimientos Petroliferos Fiscales, Argentina, were significantly modified. As a result, an important improvement in the coke conversion was observed. Five different conventional fluidized bed models using experimental data from the industrial regenerator have been tested. The analysis considers bubbles and grid jet regions, and for each model, the prediction of the regenerator performance is shown. The CSTR model is the most successful in this regard.
Computation of optimal control policy with singular subarc
Authors: Reddy K. V. , Husain Asghar 
Published: March 2009

AbstractSingular subarcs appear in the solution of an optimal control problem when one or more of the control variables appear linearly in both the performance index and differential constraint equations or just in the constraint equations. In such cases, the Pontryagin's(1) Maximum Principle yields no information regarding the possible candidates for such subarcs to be optimal trajectories, since the associated Hamiltonian is also linear in the control variables. In the chemical engineering literature such problems have been reported, for instance, in the optimal control of a continuous stirred reactor(2,3,4) in the optimally distributed feed reactors(5), in the optimal catalyst distribution along a tubular reactor(6,7) and in the optimal design of a plug flow tubular reactor(8).
Effect of the physical properties of gas on the volume of bubble formed from a submerged single orifice
Authors: Tsuge Hideki , Tanaka Yasumitsu , Hibino Shin‐Ici 
Published: March 2009

AbstractThe effects of the gas properties on the volume of a bubble formed from a submerged single orifice in the presence of pressure fluctuations in the gas chamber are investigated experimentally. The bubble volumes are affected by the specific heat ratio of gas and/or the gas density depending on the dimensionless capacitance number Nc.An extended two stage bubble formation model is proposed by considering the physical properties of gas. The bubble volumes calculated by the present model compare reasonably well with the experimental results.
Hydrodynamicst axial mixing and mass transfer in rotating disk contactors
Authors: Zhang S. H. , Ni X. D. , Su Y. F. 
Published: March 2009

AbstractCorrelations for predicting characteristic velocity both above and below the critical rotor speed have been obtained under conditions with and without solute transfer.It has been found that (1) above the critical rotor speed, the characteristic velocity U0 is proportional to g/DrN2, whereas below this value a transition region exists where Uo is proportional to (g/DrN2)0.26; (2) multiple regression analysis of the experimental data of continuous phase axial mixing shows that the axial dispersion coefficient varies not only with the rotor speed and modified velocity of continuous phase but also with the velocity of dispersed phase.With varying RDC operations, the true value of Kod corrected for axial mixing changes continually between the limiting values predicted from stagnant and fully turbulent drop models. However, the highest experimental values were only 30 to 40% of those predicted by the Handlos‐Baron model at the same drop Peclet number.
Dispersion and hold‐up in bubble columns — comparison of rigid and flexible spargers
Authors: Rice Richard G. , Tupperainen Jorma M. I. , Hedge Robyn M. 
Published: March 2009

AbstractThe performance of a new type of bubble generating device, the rubber sheet sparger, is contrasted and compared with rigid spargers. Impulse response tests were analyzed using the weighted‐moments method to determine voidage and dispersion coefficients in counter‐current bubble columns of nominal diameters two, four, six and twelve inches. The flexible rubber sheet sparger produced more uniform emulsions, smaller bubbles and larger voidages than perforated plates, while dispersion coefficients were reduced for a range of superficial gas velocities. The dispersion data seem to fit the isotropic turbulence model, with slight modifications. It is demonstrated that the rubber sheet sparger is self‐regulating, with hole size increasing in direct proportion to pressure drop across the sparger.
A simplified driving force model for activated carbon adsorption
Authors: Peel R. G. , Benedek A. 
Published: March 2009

AbstractThe use of two simplified driving force expressions are investigated for describing the intraparticle rate behaviour during adsorption onto activated carbon. A previously developed numerical solution to the surface diffusion model is used to compare the linear and quadratic driving force approximation when non‐linear isotherms and time variant boundary conditions are present. The results show that while the linear driving force equation is a poor approximation of the exact solution, the quadratic driving force is a good approximation, and its use in a kinetic model of activated carbon adsorption gives as good a description of adsorption behaviour as is given by the more detailed surface diffusion model. The driving force model has the advantage of being easier to solve, and the numerical solution requires significantly less computational effort.
A novel approach to spray drying using plasmas of water vapour
Authors: Gauvin W. H. 
Published: March 2009

AbstractThe technical feasibility of drying an aqueous solution in the form of a fine spray of droplets in contact with the water vapor generated by the evaporation of the solution has been amply demonstrated in the course of the extensive experimental work which accompanied the development of the Atomized Suspension Technique (AST). In the present paper, it is proposed to replace the external heating formerly used in an AST system by a stream of plasma‐generated superheated steam as the sole source of heat. The ratio of plasma steam required to total evaporation (circa 1 to 24) is extremely low. Based on a computer program developed in this laboratory, a simulation of the proposed operation is presented for an industrial installation. The calculations indicate that a considerable reduction in equipment size should result. No gas compression is required and operation under pressure is now possible. Most important is the considerable saving in energy resulting from the recovery of the heat in the exhaust steam from the process. An approximate estimate of capital and operating costs is presented.
Conversions and temperature rises in a tubular flow reactor with uncontrolled wall heat transfer
Authors: Golding J‐A. , Vena F. , Gorowski D. 
Published: March 2009

AbstractA study has been made of the acetic anhydride‐water reaction in a flow reactor where there was heat loss from the reactor wall. Runs were carried out at varying inlet acetic anhydride concentrations and Reynolds numbers. The laminar flow model with heat loss at the wall was found to give good agreement with experimentally observed conversions and overall temperature rises. In addition, predicted radial profiles for this model gave a better representation of measured temperature profiles than had been obtained when assuming reaction conditions were adiabatic.
Studies of molybdena‐alumina catalysts. X. temperature programmed desorption of H2S and thiophene
Authors: Ramachandran R. , Massothm F. E. 
Published: March 2009

AbstractTemperature programmed desorption (TPD) and reduction (TPR) studies were carried out on H2S and thiophene adsorbed on Mo/Al2O3 and CoMo/Al2O3 catalysts. Freshly sulfided and pyridine poisoned catalysts were run. For sulfided catalysts, the major products of desorption of thiophene were thiophene and butene, leaving a carbonaceous residue. Subsequent TPR in H2 effected complete removal of the residue with formation of H2S, thiophene and butene. The residue appeared to consist of an easily reactive thiophene polymer and a less‐reactive, sulfur‐containing coke. Runs on poisoned catalysts showed less adsorption but product profiles were similar, showing that the adsorption characteristics of the remaining sites were not significantly altered.
Determination of active metal sites in metal oxide catalysts by selective gas chemisorption
Authors: Parkash S. 
Published: March 2009

AbstractChemisorption behavior of hydrogen, carbon monoxide, nitric oxide and ethylene on three iron and three cobalt moly catalysts has been investigated in an attempt to determine active metal sites. Mode of adsorption for nitric oxide and of ethylene whether of associative or dissociative nature on the metal surface has been discussed in relation to hydrogen and carbon monoxide chemisorption. There appears to be a definite correlation between the amounts of hydrogen and carbon monoxide (VH/VCO = 1), between carbon monoxide and nitric oxide (VNO/VCO = 1.2) as well as between carbon monoxide and ethylene (CCO/V = 2) chemisorb. ed. The data suggest that the selective chemisorption behavior of nitric oxide and of ethylene should provide a suitable method to determine active metal sites in metal oxide catalysts.
Characterization of zeolitic acidity I. The cracking of 2 mole % n‐Butane over a fixed zeolite bed
Authors: Rastelli H. , Lok B.M. , Duisman J. A. , Earls D.E. , Mullhaupt J.T. 
Published: March 2009

AbstractThe use of a two mole percent n‐butane in helium stream in a fixed bed mini‐reactor at a temperature of 500°C over a zeolite bed (20 to 40 mesh and ≤ 5 grams in weight) was found to be a good tool for characterizing zeolitic acidity. In a broad spectrum of various kinds of zeolites tested, the test results are especially useful in differentiating the extremely active materials from the very active ones. Among the zeolites tested, the decreases in the order of HΩ > H‐Zeolon > NH4‐ZSM‐5 > NH4Y (thermally modified) > NH4‐erionite (thermally modified) > > HKL > NH4Y > NaY ˜ amorphous silica‐alumina. The calculated first order rate constant covered a range from over 100 to 0.5 cm3/g•min.
Turbulent mixing in free swirling jets
Authors: Grandmaison E. W. , Becker H. A. 
Published: March 2009

AbstractMarker nephelometry was used to study the nozzle fluid concentration field of free swirling turbulent jets. Swirl was generated by guide vanes in a 7.14 cm diameter nozzle with swirl numbers of 0.22, 0.36, 0.61 and 0.68 as determined by direct measurement of the linear and angular momentum fluxes for the jets. The parameters measured include those describing the self‐preserving forms of the mean concentration field, the intensity and integral scale of the concentration fluctuations, and the intermittency for the jets without internal recirculation (swirl number < 0.6). Results show that swirling jets without internal recirculation are very similar in structure. The data for the two jets with internal recirculation zones are given as contour maps describing the mean concentration and fluctuation intensity fields. The results as a whole describe jets with weak to moderate swirl and indicate trends to be expected for jets with strong swirl.
Analysis of fluid friction in dense‐phase pipeline flow
Authors: Wilson Kenneth C. , Brown Nigel P. 
Published: March 2009

AbstractIn horizontal dense‐phase slurry transport the pressure gradient is the sum of two components. The particle‐contact component, which was evaluated previously, is independent of flow velocity. It is now shown that the second component can be found in terms of a friction factor which depends on a Reynolds number based on flow velocity and particle diameter. The form of the dependence has been evaluated from theoretical considerations, and the results show a gratifying accord with the experimental data. In addition to dense‐phase flow, the findings should be applicable to other cases with a sliding bed of solids.
Study of the development of mass transport paths via an electrochemical flow visualization technique
Authors: Quraishi M. S. , Fahidy T. Z. 
Published: March 2009

AbstractMass transport patterns in natural convection generated in non‐flow cells at horizontal electrodes have been studied by an electrochemical visualization technique. Sharp colour changes in the thymbol‐blue indicator during electrolysis, due to local pH‐variations occurring in the cathodic boundary layer allow direct tracing of the propagation of flow filaments into the electrolyte bulk. The results provide direct evidence for the enhancing effect of magnetic fields on electrolytic mass transport rates and for the existence of horizontal velocity components of appreciable size at the convective surfaces.
Étude des caractéristiques de l'ecoulement créé par une turbine à Barreaux croisés dans une cellule de flottation — Influence du nombre de barreaux et de la viscosité Du liquide ii • puissance consommée et analyse spectrale
Authors: Costes J. , Alran C. , Couderc J. P. 
Published: March 2009

AbstractLes influences du nombre de barreaux d'une turbine à barreaux croisés et de la viscosité du liquide sur les résultats de l'analyse spectrale du signal anémométrique dans une cellule de flottation ont été déterminées. Les spectres de fréquence et coefficients d'autocorrélation, les échelles intégrales temporelles et spatiales, le coefficient de diffusion turbulente, le taux de dissipation locale d'énergie et la microéchelle de turbulence ont été précisés et leurs caractéristiques commentées.
Some characteristics of concentration fluctuations in free turbulent jets
Authors: Grandmaison E. W. , Rathgeber D. E. , Becker H. A. 
Published: March 2009

AbstractBecker, Hottel and Williams have employed marker nephelometry to determine many characteristics of the nozzle fluid concentration field of the round turbulent free jet: the mean concentration, concentration fluctuations, intermittency factor, spectrum and correlation functions, and integral scales. In the present work a much larger jet nozzle was employed, 7.14 cm throat diameter compared to 0.635 cm in the reference, and the Reynolds number was correspondingly greater, around 270,000 compared to 54,000. The results support Becker et al's findings and extend the range of the data. In particular, the spectrum of the concentration fluctuations has been measured into the viscous convective subrange where a (‐1) power mode dependency on wave number is indicated, as expected for the slow diffusing smoke marker. Other new measurements include the skewness, kurtosis, and probability density function of the concentration fluctuations.
Bubble deformation in high‐velocity gas injection
Authors: Anagbo P. E. 
Published: March 2009

AbstractWhen pressurised gas is injected into liquid at high velocity, the bubbles of dispersion are not exactly spherical as normally assumed in theory. High speed photographs of the dispersion show that the bubbles are spheroidal and distinctly prolate in the direction of gas flow.A mechanism of bubble deformation based on the dissipation of the kinetic energy of the injected gas is proposed in this work. The theoretical results are compared with experimental measurements of bubble deformation during high‐velocity injection of air and hydrogen through submerged plate orifices into water.
Hydraulic behavior of synthetic non‐woven filter fabrics
Authors: Rollin A. L. , Denis R. , Estaque L. , Masounave J. 
Published: March 2009

AbstractThe filtration performance of non‐woven thick synthetic membranes used as filter fabrics is predicted from a proposed analytical method. The morphological analysis of many commercial fabrics has been utilized to identify internal structure parameters responsible for their hydraulic properties and also to predict the water permeability and the retention of particles in these fabrics.Experimental filtration tests were performed to gather data on the water permeability used in predicting clogging level. Also fibres' density and pore size histograms of fabrics were measured with an Image Analyser and a relationship was developed between the water permeability and the fibres' density.Finally it was found that the pore size histogram of non‐woven fabrics of thickness greater than 1.5 mm could be calculated simply by measuring its water permeability and using an empirical correlation.
Rheology and tensile properties of polypropylene reinforced with glycerol‐treated mica
Authors: Juskey Victor P. , Chaffey Charles E. 
Published: March 2009

AbstractMica platelets were left untreated or coated with glycerol at 1%. 5% or 10% by mass, and extruded in carboxyl‐modified polypropylene at volume fractions up to 20%, and at temperatures between 468 and 528 K. At a shear rate of 10 s and at 500 K, the Einstein coefficient decreased from 2.1 when glycerol was added. The flow behavior index, ranging between 0.57 and 0.45, decreased when the shear rate or amount of mica or of glycerol was increased, while the opposite occurred when the temperature was raised. In the solid state, the tensile modulus increased, but the tensile strength was degraded.
An overview of discrete stochastic controllers: Generalized PID algorithms with dead‐time compensation
Authors: Harris T. J. , Macgregor J. F. , Wright J. D. 
Published: March 2009

AbstractDigital computer control systems have enabled use of a wide variety of different algorithms compared with the classical analog proportional‐integral‐derivative controllers. Design techniques have been presented for many of these in diverse areas of the literature. Some algorithms are designed to give minimum time responses, or to give specified closed loop responses, or to satisfy classical guidelines for stability. By contrast, the design of discrete optimal stochastic controllers is not based on considerations such as stability, frequency response, or dead‐time compensation properties, but rather on optimizing some criterion of performance such as the output error variance. Therefore, it is of interest to investigate how these controllers behave with respect to some of the more traditional ways of evaluating or designing controllers. In this paper, both intuitive and theoretical arguments are presented to illustrate the very desirable properties of these controllers and their relationship to many other algorithms. In particular, they are shown to contain proportional‐integral‐derivative terms and to be related to other well‐known controllers, to have optimal compensation for process dead‐time and optimal filtering properties, and to have very desirable stability and frequency response characteristics. In this sense, the paper provides a unifying overview of univariate stochastic controllers.