bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental investigation of some hydrodynamic factors affecting slurry pipeline wall erosion
Authors: Shook C. A. , McKibben M. , Small M. 
Published: March 2009

AbstractUsing a non‐intrusive technique, particle velocities and concentrations have been measured as functions of position on the pipe wall for water slurries of two different sands. The experimental conditions correspond to both low (fine particles) and high contact load flows.Although the velocity and concentration distributions for the two sands were quite different, flux distributions computed from the product of velocity and concentration were similar. The flux distributions are used to interpret wall erosion distributions for sands of these sizes. In the case of the coarser sand, there is evidence that the contact load mechanism contributes significantly to abrasive wear. In this case, scaleup of erosion test results may be possible, using concepts provided by mechanistic flow models. For the finer sand, wall erosion rates appear to be reduced by a lubrication force.
The phase behaviour of the propane‐water system: A review
Authors: Harmens A. , Sloan E. Dendy 
Published: March 2009

AbstractThe paper gives an integral description of the phase behaviour of the propane‐water system from very high to very low pressures in the form of a series of consecutive isobaric T, x‐diagrams. A new p, T — projection is presented. Didactic aspects are emphasised and the heuristics of the relationships between the diagrams outlined. Special attention is given to the equilibria involving hydrates. Other aqueous binary systems of similar behaviour are briefly summarised.
Écoulements et transferts de chaleur dans les Échangeurs à plaques traitant des produits visqueux newtoniens et pseudoplastiques 1. Modélisation des variations du diamètre hydraulique
Authors: Leuliet Jean‐Claude , Maingonnat Jean‐François , Lalande Marc 
Published: March 2009

AbstractLes performances d'un échangeur de chaleur à plaques sont souvent traduites par des corrélations qui contiennent le diamètre hydraulique, généralement calculé comme valant deux fois la distance entre‐plaques. Nous avons observé expérimentalement que cette valeur de la distance entre‐plaques n'était pas constante, mais dépendait des paramètres tels que le serrage des plaques entre elles et/ou la pression des fluides au sein des canaux. Les variations de cette distance entre‐plaques avec les conditions opératoires ont été étudiées à travers des mesures de chute de pression pour l'écoulement isotherme de fluides Newtoniens. Deux types de plaques ont été testés: des plaques à cannelures droites et des plaques de type chevrons.Pour les plaques à cannelures droites expérimentées, la valeur de la distance entre‐plaques est indépendante de la pression des fluides dans les canaux. En revanche, elle peut ětre multipliée par 1.18 quand on passe d'un serrage où toutes les plaques sont bien en contact à un serrage proche de la fuite. Pour les plaques de type chevrons, la valeur de la distance entre‐plaques dépend à la fois du serrage de l'appareil et de la pression des fluides, et a varié au maximum dans un rapport 1.52. Les variations de cette distance entre‐plaques ont été modélisées à l'aide de relations simples qui ont permis d'obtenir, pour les deux échangeurs et pour l'ensemble des régimes d'écoulement, une courbe de frottement indépendante du serrage des plaques et de la pression des fluides.
Extended fourier series solutions for diffusion problems with irregularly shaped boundaries and mixed boundary conditions
Authors: Ruth Douglas 
Published: March 2009

AbstractA general method is developed for the solution of any two‐dimensional, linear diffusion problem which possesses at least one straight line of symmetry. This method is based on extending the classic Fourier series solution to emcompass problems with irregular boundaries and mixed boundary conditions. In order to validate the technique, it is applied to problems with known answers, or to problems which may be solved in more than one coordinate system. The method is demonstrated to be accurate and easily implemented on a desk‐top type computer. The procedure is suitable for solving complex problems for their own sake, or for validating numerical computer codes. Extensions of the method to three dimensions and problems with convective boundary conditions are discussed.
Linearization of diffusion equations with chemical reaction: Generalization of Hikita‐Asai approximation
Authors: Asai S. 
Published: March 2009

AbstractA technique is presented for the linearization of the reaction term of the differential equations describing mass transfer accompanied by chemical reaction, which is nonlinear with respect to the concentration of a solute transferring across the interface between two phases. The proposed approximation is demonstrated to yield remarkable accuracy by the analysis of a few diffusion problems under steady and unsteady state conditions.
The role of hydrogen in coal particle disintegration at elevated temperatures
Authors: Pozzobon Robert A. , Shaw J. M. , Yushun Sun 
Published: March 2009

AbstractCoal particle size is considered to be a variable of secondary importance in coal/oil co‐processing and coal liquefaction. This finding is inconsistent with the proposed mechanism for coal particle disintegration, and product yields realized in previous large scale dissolution experiments. Coal particles are shown to break up as a consequence of hydrogen‐coal interactions occurring during preheating. The proposed mechano‐chemical mechanism for coal particle disintegration was identified through direct observation of disintegrating coal particles at elevated temperatures and pressures. Implications for the design of preheaters for coal/oil co‐processing and coal liquefaction are discussed.
Natural convection heat transfer enhancement through latent heat transport in vertical parallel plate channel flows
Authors: Yan W. M. , Lin T. F. 
Published: March 2009

AbstractA numerical analysis is carried out to investigate the effects of latent heat transfer, in connection with the vaporization of a liquid film, on natural convection heat transfer in a vertical parallel plate channel. Major nondimensional groups identified are GrT, GrM, Pr and Sc. Results for Nusselt and Sherwood numbers are specifically presented for the air‐water and air‐ethanol systems under various heating conditions to illustrate the heat transfer enhancement through latent heat transfer during the evaporation processes. Considerable enhancement in heat transfer due to the exchange of latent heat was clearly demonstrated.
Testing of a spherical dual‐tipped optical fiber probe for local measurements of void fraction and gas velocity in two‐phase flows
Authors: Moujaes S. F. 
Published: March 2009

AbstractAn alternate and easy method of constructing an optical liber probe tip is presented for the study of different two‐phase flow variables such as local time‐averaged void fraction, gas velocity and interfacial bubble passage frequency. The proposed probe tip has similar response characteristics to the “U‐bend” single fiber probe and is easier to construct than the 90° wedge tipped probe. The signal from the spherical tip seems to be insensitive to changes in bubble velocity as opposed to the 90° wedge and is more advantageous at higher velocities. The signal from the spherical tip has the same time duration as the signal changes from liquid to gas and vice versa for the same bubble velocity. A simplified model is presented to describe the balance of forces around the spherical tip when a bubble is penetrated. The model offers a qualitative explanation of why the non‐dimensional response intensity decreases as the bubble velocity increases.
Study of a downward gas jet in a two–dimensional fluidized bed
Authors: Shen Z. , Briens C. L. , Kwauk M. , Bergougnou M. A. 
Published: March 2009

AbstractThe study of a downward gas jet was performed in a two–dimensional (2–D) fluidized bed of sand particles under conditions of minimum fluidization and at atmospheric pressure and room temperature. The jet shifted through a cyclic sequence of left–central–right–central–left positions. The probability of the left and right jets was 40% each, while the less stable central jet occurred only 20% of the time. Discrete probability distributions of jet presence for each of the three jet configurations and an overall distribution are presented. They show that jets are dominant along the external walls of the nozzle. The depth of the downward jet increased with air flowrate in agreement with the correlation from Massimilla and Russo (1973).
Dilute acid hydrolysis of lignocellulosics: An application to medium consistency suspensions of hardwoods using a plug flow reactor
Authors: Abatzoglou N. , Koeberle P. G. , Chornet E. , Overend R. P. , Koukios E. G. 
Published: March 2009

AbstractA one‐stage process for the high temperature rapid dilute acid hydrolysis of hardwoods, to produce simultaneously furfural and fermentable sugars, is described. A continuous plug flow reactor unit designed to hydrolyse medium consistency wood suspensions (up to 13% w/w in solids) has been operated at capacities up to 90 kg/h, with temperatures ranging from 190°C to 240°C and 20‐120 s as residence times. The final products, mainly furfural and sugars, have been analyzed using high performance liquid chromatography. Yields of 15 kg of hexoses (30% of the theoretical potential) and 10 kg of furfural (65% of the theoretical potential) for 100 kg of sawdust (dry basis) have been obtained. Two pseudokinetic modeis were used to simulate the pentosan and hexosan acid hydrolysis reactions. A Flowtran Simulation has been conducted resulting in mass and energy balances for an eventual industrial unit.
Calculation of infinite dilution activity coefficients by the NRTL and UNIQUAC models
Authors: Demirel Y. 
Published: March 2009

AbstractInfinite dilution activity coefficients have been calculated for 42 binary systems using the NRTL and UNIQUAC models. Temperature dependent parameters of the models are used in the calculations. These parameters have been estimated by using excess Gibbs free energy and enthalpy of mixing data simultaneously. The calculated values are compared with experimental infinite dilution activity coefficients obtained by extrapolation of vapor‐liquid equilibrium (VLE) data published in the literature. The agreement between the calculated and experimental values is poor for highly nonideal system. The selection of the best model is difficult and may be system dependent.
The yield stress of fibre suspensions
Authors: Bennington C. P. J. , Kerekes R. J. , Grace J. R. 
Published: March 2009

AbstractYield stresses were determined for commercial wood pulp suspensions and synthetic fibre suspensions of low and medium mass concentration. The yield stresses measured represent interfibre failure of the network rather than failure between the suspension and a solid surface. The measurements were carried out in a rotary viscometer at low yield stresses and in a concentric rotary shear tester at yield stresses in excess of 2500 Pa. The experimental results were correlated with the volumetric concentration Cv in equations of the form τy = aCbv where a and b are constant for a given fibre type. It was found that b ≃ 3, in agreement with the predictions of a theoretical model of fibre network strength based upon the interlocking of elastically bent fibres. The dependence of the yield stress on the fibre properties of aspect ratio and modulus of elasticity was not adequately predicted by the model, suggesting that fibre bending alone did not account for the network strength over the concentration range studied.
Experimental study of sawdust and coal particle mixing in sand or catalyst fluidized beds
Authors: Hemati M. , Spieker K. , Laguérie C. , Alvarez R. , Riera F. A. 
Published: March 2009

AbstractThis paper presents an experimental study in order to establish mixing and segregation conditions of wood sawdust and coal particles in a fluidized bed of sand or alumina particles. Experiments were performed at room temperature under atmospheric pressure. Simple equipment was used to divide the bed into layers and useful results could be obtained in a short period of time. The influence of fluidization velocity, time of an experiment, size and concentration of sawdust or coal particles was investigated.Uniformity of mixing was found to increase with an increase in the fluidization velocity. For u/umf less than 2.5, strong segregation occurred between sawdust and sand particles.Determination of good mixing conditions will be useful in gasification studies of sawdust and coal.
Development of mixing rules for predicting the viscosity of bitumen and its fractions blended with toluene
Authors: Mehrotra Anil K. 
Published: March 2009

AbstractA comprehensive model is presented for predicting the liquid‐mixture viscosity of bitumen and its fractions diluted with toluene. The proposed model is based on the Walther two‐parameter viscosity‐temperature correlation and a simple viscosity mixing rule. New viscosity data at 22‐100°C are presented for 14 blends of Cold Lake bitumen and its fractions with toluene. All of these data are well correlated by the Walther correlation with AAD < 2%. The predictions from a recently proposed simple mixing formula for toluene‐bitumen blends viscosity are well within an order of magnitude of the data. The blend viscosity predictions are improved substantially by use of a temperature‐dependent viscous interaction parameter. For predicting the viscosity of toluene‐diluted whole bitumen, the bitumen is characterized both as a “black‐oil” and as a mixture of five fractions or pseudocomponents. The calculation procedure for the viscosity of toluene‐diluted bitumen is outlined and the two characterization approaches are evaluated.
Factors affecting the decay of batch liquid‐liquid dispersions
Authors: Jeelani S. A. K. , Pandit A. , Hartland S. 
Published: March 2009

AbstractA model which predicts the shape of the time dependent sedimentation and coalescence profiles during batch decay, allowing for binary coalescence and increasing hold‐up in the sedimentation zone, and the effect of the height of the dense‐packed zone on the interfacial coalescence rate, is presented. The model is verified using the experimentally observed increase in drop size with time.Analysis of twenty five liquid‐liquid systems covering a wide range of physical properties, operating conditions and settler geometry indicates that sigmoidal or exponential sedimentation profiles are obtained depending on whether the initial Reynolds number is less or greater than unity, respectively.
Segregation in a stirred fluidized bed
Authors: Zhang Z. , Beeckmans J. M. 
Published: March 2009

AbstractA bed of particulate solids supported by an upward current of gas can be stirred at moderate power input per unit volume using thin horizontal rods mounted on a vertical shaft. The bed is fluidized, but bubbles are suppressed below a critical value of the fluidizing velocity. Stirring increases bed bulk density and reduces the minimum fluidizing velocity. Segregation in a stirred fluidized bed is enhanced with both flotsam and jetsam tracer particles, but the rate of segregation is reduced with flotsam tracers. The stirred fluidized bed may be useful as a device for dry separation of solids.
Devolatilization and combustion of large coal particles in a fluidized bed
Authors: Zhang J. Q. , Becker H. A. , Code R. K. 
Published: March 2009

AbstractDevolatilization and combustion of large particles of Eastern Canadian coals (Evans and Minto), 5‐50 mm dia., were studied in a bench‐scale atmospheric fluidized bed reactor at 1023‐1173 K with 0.5 mm sand particles as the bed material. The devolatilization time, mass loss history, changes in proximate volatiles content and C/H mass ratio, and temperature history at the centre of the particle during devolatilization were determined. The mass loss during devolatilization is correlated with the proximate volatiles content of the parent coal. The devolatilization time is correlated with the initial particle diameter by a power‐law relation with an exponent of 1.54‐1.64. The results show insignificant effect of superficial velocity on devolatilization.
Liquid circulation characteristics in jet loop reactors
Authors: Jain D. K. , Patwari A. N. , Khan A. A. , M. Bhagawantha RAO  
Published: March 2009

AbstractLiquid‐velocity profile measurements in the annular region of a jet‐loop reactor for a gas liquid system are reported, which facilitate evaluation of local phenomena. The range of variables studied included superficial gas velocities of 0‐16 cm · s−1 and superficial liquid velocities of 0‐0.6 cm · s−1. The main observations made with respect to the radial profile of axial liquid velocity are:a) a trend reversal in the changeover from a liquid phase system to a gas‐liquid system;b) at low gas loading rates of 1‐3 cm · s−1 it is insensitive to liquid injection rates;c) at high liquid injection rates it shows a minimum.A correlation has been proposed to predict the circulation Reynolds number for the two‐phase system.
Backmixing of liquid in horizontal multiple‐impeller vessels
Authors: Fukuda T. , Idogawa K. , Akiyoshi M. , Ando K. 
Published: March 2009

AbstractThe batch mixing model for liquid as the continuous phase of a gas‐liquid system in a horizontal multiple‐impeller vessel was applied to continuous flow operation. The back flow ratio was determined by measuring the residence time distribution. The relation between back flow ratio and operating variables was found to be similar to that for a vertical multiple‐impeller vessel. A method for estimating the back flow ratio in a horizontal multiple‐impeller vessel, from the mixing time in a single‐impeller vessel, was presented.
Heat transfer coefficients in finned‐coil stirred‐tank systems
Authors: Kizilçeç Fatma , Ilsenönsan Z. , Borak Fahir 
Published: March 2009

AbstractSteady‐state and transient heat transfer coefficients were determined for a finned‐coil, stirred‐tank system using flat‐blade turbine impellers in water. Fin spacing, flowrate, hot water temperature and agitator speed were varied for Re between 20 000 ‐ 110 000 for the agitated side.Individual transfer coefficients were calculated from the experimental overall coefficients. The correlation developed for predicting external transfer coefficients in agitated systems with finned‐tube coils was tested against transient data.
Le raisonnement qualitatif‐quantitatif de QQSIM
Authors: Tetreault Mario , Lapointe Jean , Marcos Bernard 
Published: March 2009

AbstractCette publication montre que les algorithrnes de raisonnement qualitatif manipulent les qualitiés par une caractérisation des valeurs réelles. Un exemple simple fait ressortir la signification qualitative du raisonnement de QSIM (Qualitative SIMulation), son calcul par intervalles et ses limitations. Par la suite, on propose une extension de QSIM pour intégrer differentes connaissances (règles de production, raisonnernent qualitatif, ordre de grandeur, calcul quantitatit) dans un algorithme de simulation qualitative‐quantitative (QQSIM) en qualifiant les données sous forme d'intervalles. Cette extension permet l'utilisation du raisonnement qualitatif sur un système de traitement d'eaux usèes. Pour terminer, on montre que cette approche s'applique dans un contexte de systèmes‐experts.
Analysis and tuning of adaptive generalized predictive control
Authors: Mcintosh Andrew R. , Shah Sirish L. , Fisher D. Grant 
Published: March 2009

AbstractThe adaptive Generalized Predictive Controller (Clarke et al., 1987a, b) is capable of controlling plants with variable dead‐time, unknown model orders and unstable poles and zeros. This paper shows how the GPC control law can be written in an equivalent general linear transfer function form which simplifies closed‐loop (eg. root locus) analysis. Three recommended strategies for selecting the design parameters during the commissioning stage allow the user to adjust the closed‐loop speed of response on‐line using only a single active tuning parameter. Experimental runs confirm the ability of adaptive GPC to provide a consistent closed‐loop response in spite of large process changes.
Predictive Control of a Circulating Fluidized Bed Combustor
Authors: Venugopal S. , Gupta Y. P. , Basu P. 
Published: March 2009

AbstractThe acceptance of CFB combustion in process and utility industries for generating steam has been increasing because of its ability to burn a wide variety of fuels efficiently and in an environmentally acceptable manner. Work on control of this emerging technology is beginning to appear. This paper evaluates the performance of two predictive control algorithms (the Dynamic Matrix Control and a simplified version) for control of temperature and pressure drop in a pilot scale CFB combustor. The robustness of the algorithms is studied on a model of the CFB combustor. The experimental and simulation results show the suitability of the two control algorithms for control of the CFB combustor.
Control policies for an industrial acetylene hydrogenation reactor
Authors: Brown Michael W. , Penlidis Alexander , Sullivan Gerald R. 
Published: March 2009

AbstractThis paper addresses the problem of finding optimal operational policies for an acetylene reactor for day to day operation. A lumped parameter model based on four main reactions is developed and used to examine the effects of the reactor manipulated variables on key reaction parameters. An optimal and a sub‐optimal operational policy which minimize the ethylene loss over time are formulated and the solution techniques are presented. The results indicate that the reactor model is in good agreement with industrial plant data. The performance of the optimal control policy is very similar to the performance of the sub‐optimal control policy. However, the sub‐optimal formulation, while retaining the dominant features of the optimal response, reduces the computational requirements. Finally, some issues concerning the real‐time implementation of an advanced acetylene reactor control scheme are presented. These include the estimation of the optimum regeneration cycle, a recursive model update algorithm, the process optimizer and their overall coordination. A preliminary analysis of the benefits associated with the advanced control scheme suggests a considerable reduction in the yearly ethylene loss.
Effects of wettability and pore geometry on mobilization of oil and gas in physical models and application to water‐alternating‐gas (WAG) injections
Authors: Kong V. W. Tang , Wardlaw N. C. 
Published: March 2009

AbstractExperiments in capillary tubes show that the mobilization of discontinuous oil and/or gas in a hydrophobic (oil‐wet) system requires a pressure gradient of about 6 to 7 times larger than for a comparable water‐wet system. The mobilization pressure is directly proportional to the contact angle hysteresis and interfacial tension and inversely proportional to tube radius.For experiments in glass micromodels, where pores were ∼ 3 times as large as connecting throats, mobilization pressures for oil‐wet systems were only ∼ 1.7 times as large as for equivalent water‐wet systems and pore geometry had more effect on mobilization pressure than did differences in wettability. These pore‐level events are thought to affect mobility within WAG banks used to stabilize gas drives.
Temperature field within a devolatilizing coal particle
Authors: Tomeczek Jerzy , Kowol Jan 
Published: March 2009

AbstractThe aim of the present research was to test a mathematical model of coal devolatilization. Verification of the thermal conductivity, specific heat capacity and endothermic heat of pyrolysis was carried out by measurement of the coal particle temperature at the outer surface and in the center of the particle. The model, with recommended thermal and transport data, was then tested on the basis of gaseous products generation rates and total mass loss during experiments with coal granules of size 4‐20 mm and coal grains 0.08‐5 mm dropped into a hot fluidized bed.