bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid‐liquid extraction in a reciprocating screen plate column
Authors: Chen B. H. , Liu C. H. 
Published: March 2009

AbstractA novel reciprocating‐plate liquid‐liquid extraction column is proposed. It features a simple design that utilizes as the plates mesh screens with a fractional free area larger than 64%.A hydrodynamic and mass transfer study of the column was carried out in which the existence of a uniform liquid‐liquid dispersion throughout the column at relatively low speeds of plate reciprocation was confirmed. Experimental results show that in comparison with other reciprocating columns, the present column has these desirable qualities: (1) large dispersed phase holdup and overall mass transfer coefficient, (2) low power requirements, (3) high flow capacity.A correlation of the dispersed phase holdup data based on slip and drop characteristic velocities is presented. The drop characteristic velocity for the screen plate column is empirically related to the power dissipation rate and system properties.On propose une nouvelle colonne d'extraction liquide‐liquide munie de plateaux réciproques. Il s'agit d'une conception simple qui utilise comme plateaux des tamis à mailles avec une zone libre fractionnelle supérieure à 64%.
Transient heating and cooling of cocurrent three‐phase fluidized beds
Authors: Grandjean B. P. A. , Carreau P. J. , Paris J. 
Published: March 2009

AbstractThe thermal transient behaviour of three‐phase fluidized beds have been investigated for a liquid viscosity ranging from 35 to 75 mPa · s. For the operating conditions used in this study, a 6 mm glass particle bed was found to have a thermal response similar to that of a fixed bed. The transient responses, which were not significantly affected by gas sparging, were, however, faster for heating than for cooling. This result has been analyzed from a model assuming liquid plug flow through stationary particles using combined free and forced convection correlations for heat transfer around the particles. Different correlations are then proposed to predict the contribution of natural convection to the liquid‐to‐particle heat transfer in heating and cooling modes. The effect of gas sparging was found to strongly affect The 2.0 mm particle bed responses but only moderately the 3.9 mm bed responses. These responses were analyzed using axial dispersion models for the liquid and solid phases. For the 3.9 mm particle bed, the axial dispersion coefficient of the solids, EZS, was found to be of the same order of magnitude as that of the liquid coefficient, EZL. However, the value of Ezs for the 2 mm particle bed was found to be five times that of EZL.
Pool boiling heat transfer to saturated water and refrigerant 113
Authors: Jamialahmadi M. , Blöuchl R. , Müuller‐Steinhagen H. 
Published: March 2009

AbstractPool boiling heat transfer coefficients were measured for saturated water at atmospheric pressure and for saturated refrigerant Rl13 at 102 kPa and 341 kPa. The measured heat transfer coefficients were compared with values found by other researchers and with the predictions of correlations from the literature. Bubble departure diameter, bubble frequency and nucleation site density were recorded for each experiment. A pool boiling model recently developed by Blöchl and Bier is described and limitations of the model are discussed.
Kinetics of aromatics hydrogenation of bitumen‐derived gas oils
Authors: Yui Sok M. , Sanford Emerson C. 
Published: March 2009

AbstractUsing pilot scale trickle‐bed reactors with commercial NiMo/Al2O3 catalysts, hydrotreating of five bitumen‐derived gas oils was conducted. Aromatic carbon was determined by l3C NMR spectra. A simple power law kinetic model of aromatics hydrogenation was developed, assuming a first order reversible reaction which accounts for both forward and reverse rate constants. The model includes power terms for space velocity and hydrogen partial pressure, and the ratio of naphthenes and aromatics in the feed. The model was tested with our experimental results and kinetic parameters were determined. Aromatic carbon calculated with these parameters is in good agreement with observed results.
Studies on hydrophilic polysulfone ultrafiltration membranes
Authors: Tremblay A. Y. , Tam C. M. , Guiver M. D. , Dal‐Cin M. M. 
Published: March 2009

AbstractUltrafiltration membranes were produced from carboxylated polysulfone polymers having different degrees of substitution (DS). Solute separation was found to increase with increasing DS. The techniques of single solute permeation and permoporometry were used to determine the pore size of these membranes. Permoporometry measurements indicated that pore size decreased with increasing DS. Solute separation was predicted by inserting the distribution of pore sizes obtained from permoporometry into a restricted transport model. Similar results were obtained from a nonlinear least squares fit of the restricted transport model to the experimental data. Both techniques produced similar sieving curves. It was concluded that pore size decreases were not due to the increasing repulsion of solute molecules by hydrophilic polysulfone but to changes in polymer solution properties as the DS increased.
Rheological properties of bitumen in water emulsions with added solids
Authors: Yan Yuhua , Pal Rajinder , Masliyan Jacob 
Published: March 2009

AbstractExperimental work was carried out to investigate the rheological properties of bitumen in water emulsions containing solids of different shape and size. The bitumen volumetric concentration was varied up to 60%, solids free basis, and the solids volume fraction (total volume basis) was varied up to 0.2. Irregular‐shaped silica sand (average diameter: 9 and 33 μm) and smooth spherical glass beads (average diameter: 27 and 44 μm) were used as the added solids.In the low shear stress range, shear thinning behavior was observed for bitumen in water emulsions. At high shear stress, the viscosity of the emulsions became fairly independent of the shear stress. The addition of solids to the bitumen emulsions increased the mixture viscosity. The addition of irregular‐shaped silica sand gave a higher viscosity than a similar addition of the spherical glass beads. The viscosity of the emulsion/solids mixtures was influenced by the solids size as well; the smaller size particles gave a higher viscosity.The addition of solids to the bitumen emulsions also induced shear thickening (dilatancy) behavior at high solids volume fraction. The degree of the shear thickening increased with the oil concentration.
Réacteur électrochimique à lit granulaire transporté
Authors: Benzina M. , Lacoste G. 
Published: March 2009

AbstractCe travail présente l'étude d'un réacteur électrochimique à matrice solide granulaire lorsque celle‐ci est placée dans un tronc conique. La solution à traiter percole le lit granulaire du réacteur en écoulement du fait de la gravité tout en lui assurant une bonne cohésion et donc une conductivité électronique satisfaisante.Les solutions numériques des équations différentielles liées aux bilans de masse et de charge permettent d'atteindre les distributions de concentration, de courant et de potentiel dans le cas où le lit granulaire est maintenu fixe. Une évolution de ces distributions expérimentales est discutée dans le cas où le lit granulaire est mis en mouvement.L'évolution des concentrations (écoulement piston) et l'influence des débits liquide et solide discutés et illustrés dans le cas de la récupération de cuivre de solutions diluées (< 500 ppm) d'acide sulfurique. Un diagramme de dimensionnement pour chaque cas de percolation a finalement été proposé.
Thermolysis of glycol lignin in the presence of tetralin
Authors: Thring Ronald W. , Chornet Esteban , Overend Ralph P. 
Published: March 2009

AbstractAn organosolv (ethylene glycol) hardwood lignin has been thermally treated in the presence of tetralin, a hydrogen donor solvent. The effects of reaction temperature and time on product distribution were studied as a function of a seventy index, Xc = ℓn (Rω with Rω = Δt t × exp [(Tr ‐ Tb)/ω] where Δt = time, Tr = reaction temperature, Tb = base temperature, and ω = characteristic parameter. Under the conditions used, up to 60% of the lignin can be converted to liquid and gaseous products. Syringols, guaiacols, aromatic aldehydes and ketones predominate at low treatment severities whilst phenol, catechol and their methyl and ethyl derivatives are the main monomers at high severities. Comparison of our data with parallel works is shown to be effectively done through the severity index, Xc.
Fractionation of woodmeal by prehydrolysis and thermal organosolv. Process strategy, recovery of constituents, and solvent fractionation of lignins so produced
Authors: Thring Ronald W. , Chornet Esteban , Overend Ralph P. 
Published: March 2009

AbstractA prototype hardwood Populus deltoids has been fractionated in kg quantities into its primary constitutive polymers, namely, cellulose, hemicelluloses, and lignin, under optimal recovery conditions for each fraction.Our approach is targeted at processing sawdust or finally divided wood (dp ≤ 0.5 mm) and involves a thermomechano‐solvolytic treatment of medium consistency suspensions in two process development units operated sequentially. Firstly, the hemicellulose fraction is removed from the initial wood by a aqueous‐steam pretreatment (auto‐hydrolysis) at conditions where nearly 90% of the hemicelluloses are solubilized. Secondly, the treated wood (lignocellulose) is separated into cellulose and lignin rich fractions by subjecting it to an organosolvolytic treatment using ethylene glycol as solvent. An experimental unit which can be operated in semi‐continuous or continuous modes is described and was employed for this step. The recovery of each fraction via appropriate mass balances is presented.Also, a comparative characterization of the lignins isolated via (a) the direct solvolysis route and (b) the sequential aqueous‐steam pretreatment followed by solvolysis approach is made using solvent fractionation, molar mass distribution, and 13C NMR spectroscopy methods.
Flow simulation of herschel‐bulkley fluids through extrusion dies
Authors: Mitsoulis E. , Abdali S. S. , Markatos N. C. 
Published: March 2009

AbstractThe flow of viscoplastic materials through extrusion dies has been studied numerically using the finite element method. Rheological data for viscoplastic doughs have been fitted by the Herschel‐Bulkley model, which incorporates a yield stress into the power‐law model. Non‐isothermal simulations show the extent and shape of yielded/unyielded regions and the development of temperature field assuming different modes of heat transfer at the boundaries. The results reveal that viscous dissipation causes appreciable temperature rises in the extrudate in agreement with measured values at the extruded material surface. The extrudate swell results show a maximum for a certain range of apparent shear rates also observed experimentally. However, the inelastic simulations based on the Herschel‐Bulkley model always under‐predict the experimental swelling values. A heuristic approach is also used to determine the level of elasticity required to produce the experimental values.
The role of gas phase momentum in determining gas holdup and hydrodynamic flow regimes in bubble column operations
Authors: Reilly I. G. , Scott D. S. , Debruijn T. J.W , Macintyre D. 
Published: March 2009

AbstractExperiments conducted in 0.15 m diameter bubble columns using water and non‐aqueous liquids have shown that the gas velocity at which transition from the bubbly flow to the churn‐turbulent flow regime occurs is a function of gas density. The transition velocity increased with increasing gas density. The direct effect of gas density on gas holdup in the bubbly flow regime is small with only a slight increase in holdup being observed at higher densities (ϵG α ρg 0.04). In the churnturbulent region a much greater effect of gas density on gas holdup was observed. These differences were found to be a direct function of the differences in holdup values at the transition points. Gas holdup was found to be a function of the gas phase momentum. In the bubbly flow regime holdup was directly proportional to momentum while in the churn‐turbulent regime holdup was proportional to momentum to the one third power.Reasons for this behaviour are discussed, as well as the implied effects on liquid mixing in bubble column slurry reactors. The effects of gas density may offer an explanation for some apparently anomalous published results.
Wall effect on mixed convection from horizontal surfaces with a variable surface heat flux
Authors: Aldoss T. K. , Jarrah M. A. , Duwairi H. M. 
Published: March 2009

AbstractThis work investigates analytically the wall effect on the mixed convection from a horizontal plate embedded in porous media. Variable surface heat flux is assumed at the plate. The wall effect due to no‐slip boundary condition at the wall is introduced using the Brinkman model. Two sets of transformations are used, one for the forced convection dominating regime (FCDR) and the other one for the natural convection dominating regime (NCDR). The wall effect is found to be characterized by the boundary parameters L = DaxPex /ϵ in FCDR and by M = Dax Ra:/ϵ in NCDR. Velocity as well as temperature profiles are calculated at different values of governing parameters. Local Nusselt number variation for the entire mixed convection regime is also calculated and presented. Accurate correlations for local and average Nusselt number valid for the entire regime of mixed convection and for the range of boundary‐parameter from 0 to 100 are obtained.
Analysis of a ring‐shaped sensor for use in packed‐bed heat transfer studies
Authors: Giudici Reinaldo , Do Nascimento Cláudio AugustO Oller 
Published: March 2009

AbstractA new type of ring‐shaped temperature sensor for packed‐bed heat transfer studies is presented. This ring‐shaped sensor is easy‐to‐build and allows one to filter the experimental angular temperature fluctuations. This device is more effective for beds of small tube‐to‐particle diameter ratio. The proposed device is able to eliminate the effect of the angular position on temperature measurements in packed beds. This sensor property is confirmed both experinientally and theoretically. For demonstration purpose, packed beds of six different materials were studied. Effective thermal radial parameters obtained using the ring‐shaped sensors have shown trends similar to published packed‐bed heat transfer data.
Reactivation of partially‐sulphated limestone particles from a cfb combustor by hydration
Authors: Couturier M. F. , Marquis D. L. , Steward F. R. , Volmerange Y. 
Published: March 2009

AbstractSpent limestone samples from the bed and baghouse of a 22 MWe circulating fluidized bed (CFB) boiler were hydrated and then sulphated in a thermogravimetric analyzer under conditions similar to those found in CFB combustors (850°C, 0.3% SO2, 9% O2, 9% CO2 and 81.7% N2). Hydration using water gave faster rates and higher levels of conversion of the residual CaO to Ca (OH)2 than immersion in pure steam at 150 and 200°C. The particles expanded during hydration and their internal volume increased from 0.1 cm3/g Ca before hydration to nearly 0.6 cm3/g Ca after dehydration. Hydration rejuvenated the reactivity of the bed material but not that of the baghouse particles. The conversion of Ca to CaSO4, in the treated bed particles increased from 32% to over 80% during re‐sulphation.
Minimum spouting velocity in multiple spouted beds
Authors: Murthy D. V. R. , Singh P. N. 
Published: March 2009

AbstractStudies have been carried out in multiple spouted beds having 2, 3 and 4 spout cells; different fluid inlet orifices and different solids have been used with air and water as spouting fluids. The minimum spouting velocities are measured for different bed depths. The experimental data for particle Reynolds number at minimum spouting have been correlated and the square root mean deviation between the calculated and experimental values is found to be 8.75 %.
Diffusion in liquid‐filled pores of activated carbon. I. Pore volume diffusion
Authors: Leyva‐Ramos R. , Geankoplis C. J. 
Published: March 2009

AbstractThe adsorption isotherms on activated carbon were measured for the following six systems: benzaldehyde, phenol, and potassium chloride in water; benzene, isopropylbenzene, and phenol in cyclohexane. The systems isopropylbenzene and benzene each in cyclohexane and potassium chloride in water proved to be slightly adsorbing systems, whereas the benzaldehyde and phenol each in water were highly adsorbing systems. The rate of diffusion of the slightly adsorbing solutes was interpreted by assuming that the intraparticle diffusion was due to pore volume diffusion. The results indicated that the tortuosity factor for activated carbon is 3.5. The effective pore volume diffusivity and the tortuosity factor were not affected by the concentration of the solute, solute molecular size and the particle diameter. The external mass transfer resistance was negligible when pore volume diffusion was the controlling intraparticle diffusion mechanism.
Characterization of robust performance using response surfaces
Authors: Krishnapura Venugopal G. , Jutan Arthur 
Published: March 2009

AbstractDesign of robust controllers in the face of process model uncertainty is an important problem. The new design methodologies in the frequency domain have sought to address some of the issues involved in robust control. Never‐theless, the characterization and measurement of uncertainty remains a somewhat difficult and abstract task. In order to easily compare and characterize robust performance of alternate stable control structures, it would be useful to have an intuitive, easily applicable measure of robust performance. In this paper we propose a new time domain based measure of robust performance using geometric concepts borrowed from Response Surface Methodology. The measure is used to characterize robust performance of single‐input‐single‐output systems. Simulations results are provided to illustrate the use and intuitive appeal of the new measure.
Cake filtration of suspensions in viscoelastic fluids
Authors: Kozicki W. , Kuang P. Q. 
Published: March 2009

AbstractThe fundamental framework for cake filtration of suspensions in viscoelastic media is extended to include the effects of polymer retention, including adsorption in the filter cake, polymer retention and elongational flow in the filter medium, which also undergoes compaction, and evaluation of polymer degradation in the filter cake and medium. Experimental data obtained in constant pressure filtration of starch suspensions in dilute aqueous polyacrylamide solutions confirmed the prediction of an enhanced apparent medium resistance Rma and a reduced cake resistance αR. Evaluations are presented of the contributions to the pressure drop due to enhanced normal stresses in elongational flow and to polymer retention (adsorption), and of the ratio of the particle size with and without adsorbed polymer in the cake. The analysis of the data points to high levels of polymer degradation during the flow of the polymer solution through the filter cake and medium.
The operating cost of electrocoagulation
Authors: Donini J. C. , Kan J. , Szynkarczuk J. , Hassan T. A. , Kar K. L. 
Published: March 2009

AbstractThe electrocoagulation of kaolinite and bentonite suspensions was studied in a pilot electrocoagulation system at the Western Research Center of CANMET to assess the operating cost and efficiency of the process. Factors affecting the operating cost such as, the formation of passivation layers on electrode plates, flow velocity and concentration of sodium chloride in the suspension were examined. The operating costs investigated in this paper were the power cost of the electrocoagulation cell and the material cost due to the consumption of the aluminum electrode. Comparison was based on the settling properties of the treated product: turbidity, settling rate, and cake height. Higher concentration of sodium chloride resulted in greater amount of aluminum dissolved chemically and electrochemically into the suspension and thus a better clarity of the supernatant of the treated product. Increased flow velocity could reduce significantly the operating cost while improving both clarity of the supernatant and the compactness of the sludge volume. The passivation layers developed quickly with time during the electrocoagulation process and more energy became wasted on the layers.
Kinetic of copper ion exchange onto iminodiacetic resin
Authors: Mijangos F. , Diaz M. 
Published: March 2009

AbstractThe internal porosity and swelling/shrinking of a chelating iminodiacetic type ion exchange resin have been experimentally studied during the uptake of copper onto it. The swelling of the particle could be analyzed with a modified model on th basis of the unreacted core model (UCM), including the influence of chemical equilibrium. The ion exchange kinetic results in batch experiments are used with the UCM to calculate the effect of pH on the internal diffusion coefficients. Results from shallow bed experiments with mixed internal and external diffusion controls have shown the applicability of the above model to analyze ion exchange with low external velocities.
Optimization of impeller design for gas inducing type mechanically agitated contactors
Authors: Mundale V. D. , Joshi J. B. 
Published: March 2009

AbstractRates of gas induction and fractional gas hold‐up were measured in a 0.57 m i.d. gas inducing type mechanically agitated contactor. Several designs of the impeller were employed for optimizing the rate of gas induction with respect to power consumption. The effect of blade width blade, angle, blade thickness, blade curvature, number of blades, etc. on gas induction, has been investigated in detail. An optimum design has been proposed. Hysteresis in the gas induction rate and power consumption was observed for a wider impeller projecting out of stator.
Retained properties of concrete exposed to high temperatures: Size effect
Authors: Arioz Omer 
Published: March 2009

AbstractConcrete as a construction material is likely exposed to high temperatures during fire. The retained properties of concrete after such exposures are still of great importance in terms of the serviceability of structures. This paper presents the effects of high temperatures on the physical, mechanical, and microstructural properties of concrete. Specimens with different sizes were exposed to high temperatures ranging from 200 to 1200∘C. The compressive strength, splitting tensile strength, ultrasonic pulse velocity, and rebound numbers of the specimens were determined. The microstructures of the specimens were examined by scanning electron microscope (SEM) analyses. The test results indicated that the retained compressive strength of concrete considerably decreased with increase in temperature. The effect of specimen size on the retained compressive strength was not pronounced. The retained splitting tensile strength of concrete remarkably reduced as the temperature was increased. The specimen size played an important role on the retained splitting tensile strength of concrete up to 400∘C. The test results revealed that ultrasonic pulse velocity (UPV) test can be successfully used in order to check the uniformity of fire‐damaged structures. The rebound numbers decreased with increase in exposure temperature. SEM studies on specimens exposed to 800∘C revealed significant changes in the microstructure of the concrete. Copyright © 2009 John Wiley & Sons, Ltd.