bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of entrainers in heteroazeotropic distillation systems
Authors: Furzer I. A. 
Published: March 2009

AbstractGroup contribution methods have been used to synthesise entrainers in the series, n‐alkanes, aromatics, cycloalkanes and branched alkanes. The separation of ethanol from the synthesised entrainers depends on the size of a loop on the thermodynamic x‐y diagram. Very easy separations are possible with hexane and 2,2‐dimethylbutane, leading to high purity ethanol. A set of heuristic rules is proposed as a knowledge database to assist expert systems to identify the optimal entrainer.
Modified oil agglomeration process for coal beneficiation. III. Grinding and agglomeration using different szego mill designs
Authors: McCracken Thomas W. , Trass Olev 
Published: March 2009

AbstractThe simultaneous grinding/agglormeration process has been used to beneficiate Minto coal. Experiments with the Szego Mill, a planetary ring‐roller mill with grooved rollers, have given good results. Different roller ridge/groove sizes have been tested and favourable oil‐coal‐water ratios established. Ash removal is closely related to grinding performance. Very short mill residence times, of the order of 10 seconds, are sufficient for microagglomerate formation. Considerable equipment and operating cost savings are possible with the modified process.
Mixing in the transition flow regime with helical ribbon agitators
Authors: Cheng Jianya , Carreau Pierre J. 
Published: March 2009

AbstractThe effects of the non‐Newtonian properties on the effective deformation rate, mixing and circulation times and flow behaviour have been investigated in the transition flow regime of mixing systems. Based on the equivalent Couette flow, three models are proposed and are shown to predict similar and drastic increases of the effective deformation rate with the impeller rotational speed in the transition regime. The predictions are shown to fit very well data obtained for various non‐Newtonian fluids mixed with helical ribbon agitators, and with literature data for anchor, blade turbine and flat disc agitators. The elasticity along with shear‐thinning properties appear to have slight effects on the dimensionless mixing and circulation times in the transition regime, whereas their effects in the laminar regime are quite drastic, as reported by others.
A bifurcation study of convective heat transfer in a hele‐shaw cell
Authors: Ryland D. K. , Nandakumar K. 
Published: March 2009

AbstractSteady‐state multiplicity characteristics of convective heat transfer within a Hele‐Shaw cell are investigated. The Navier‐Stokes equations and the energy equation are averaged across the narrow gap, d, of the cell. The resulting two‐dimensional, stationary equations depend on the following parameters: (i) the length to height aspect ratio γ, (ii) the tilt anle ϕ (iii) the Prandtl number Pr, (iv) an inertia parameter ξ = d2/ 12a2, and (v) the Grashof number. Gr = Qgβga5/kv2. Here a is the height of the cell and Q, is the heat generation rate per unit volume. The complete structure of symmetric and asymmetric stationary solutions are traced using recent algorithms from bifurcation theory. In the double limit of ξ → 0 and Gr → ∞ such that Ra = 4GrPrξ remains finite (where Ra is the Rayleigh number for the Darcy model) the Hele‐Shaw model reduces to that of the Darcy model.
Modelling the influence of osmotic pressure gradients, interstitial volume, and lymphatic action on mass exchange in body tissues
Authors: Taylor D. G. 
Published: March 2009

AbstractA mathematical model was employed to study the relative influences of interstitial osmotic pressure gradients, interstitial volume, lymphatic action and system geometry on the transcapillary exchange of fluid and plasma proteins within a modified Krogh cylinder tissue unit. The model includes a description of lymphatic behaviour and incorporates modified versions of the fluid and membrane transport equations to describe interstitial fluid flow under the influence of protein osmotic pressure gradients. The subsequent analysis suggests that these gradients have little effect on the overall hydrodynamics within the tissue. However, the properties of the draining lymphatic vessel and the radial dimension of the tissue cylinder exert strong influences on the magnitude and distribution of fluid and plasma protein fluxes across the capillary wall. The results of these simulations challenge current assumptions about transcapillary fluid flux distributions since they predict little exchange near the arteriolar end of the system in many cases. Further, as the radial dimension of the cylinder increases, the capillary moves from a state of fluid filtration along its entire length to one in which reabsorption occurs near the venular end of the blood vessel.
Biodegradation of 2,4‐dichlorophenoxy acetic acid (2,4‐d) by pseudomonas cepacia: Stoichiometric study
Authors: Fradette Sylvie , Leduy Anh , Rho Denis , Samson Réjean 
Published: March 2009

AbstractPseudomonas cepacia biodegraded 2,4‐dichlorophenoxyacetic acid (2,4‐D) according to the following stoichiometric equation:C8 H6 Cl2 O3 + c1 O2 + c2 NH3 → c3 CHx Nz Oy + c4 CO2 + c5 H2 O + c6 Cl− + c7 REIMwhere CHx Nz Oy represents the bacterial cells and REIM is the residual extracellular intermediate metabolites. The stoichiometric coefficients c1 to c7 were determined from C, N, O, H and Cl balances together with the experimental data on the biodegradation of 14 C‐carboxy‐labeled‐2,4‐D and 14 C‐ring‐uniformly‐labeled‐2,4‐D. The stoichiometric equation obtained predicted satisfactorily the total oxygen consumption for and the total heat production from the biodegradation of 2,4‐D for a wide range of initial concentrations from 80 to 500 mg/L.
Efficiency of dualflow trays in distillation
Authors: Xu Z. P. , Afacan A. , Chuang K. T. 
Published: March 2009

AbstractThe mass transfer efficiencies of dualflow trays with open hole areas of 20, 28 and 37% were experimentally investigated under total reflux conditions in a 300‐mm diameter distillation column using methanol‐water and methanol‐isopropanol systems. The results indicate that the efficiency of a dualflow tray is a strong function of the open hole area, the vapor/liquid load, and liquid properties such as surface tension and density. A fundamental model was developed to predict tray efficiency. The prediction was found to agree with the measured data to within 15.3%.
Effects of surface tension on tray point efficiencies
Authors: Chen G. X. , Afacan A. , Chuang K. T. 
Published: March 2009

AbstractSieve tray efficiencies for the distillation of methanol/water, acetic acid/water and cyclohexane/n‐heptane mixtures were measured as a function of composition under fixed vapour and liquid rates in a 0.15 m diameter distillation column. Experimental results show that surface tension has a significant effect on tray efficiency and the number of transfer units. Further tests in a simulator column with air/water, air/methanol and air/(water + surfactant) systems having different surface tensions revealed that bubble sizes in froths are mainly determined by surface tension. The results also show that bubble break‐up and coalescence occurs in the froths.
Anode slime behaviour in a laboratory‐scale copper electrorefining process
Authors: Ling X. , Gu Z. H. , Fahidy T. Z. 
Published: March 2009

AbstractCombining conventional electrochemical measurements, laser‐based visualization and digital image processing, the movement of anode slime, its spatial distribution and path of falling during the copper electrorefining process were investigated in a laboratory scale cell. Two types of anode slime, small agglomerates and fine particles were observed. The behaviour of the slime was found to be closely related to the electrolyte circulation pattern. Different circulation rates and direction can only change the magnitude of the falling rate of small agglomerates, but not its direction. The path of falling is essentially random. By contrast, the direction of circulation can change both the rate of movement and the direction in the case of fine‐particle slimes. Downward circulation accelerates the rate of settling; the higher the circulation rate, the faster the rate of slime removal from the cell
A diverse approach for the solution of the isothermal multiphase flash problem. Application to vapor‐liquid‐liquid systems
Authors: Stateva Roumiana P. , Tsvetkov Stefan G. 
Published: March 2009

AbstractThe paper presents a novel approach for the solution of the isothermal multiphase flash problem with particular application to systems exhibiting liquid‐liquid‐vapor equilibria. The approach includes a rigorous method for thermodynamic stability analysis as a first step and an efficient phase identification procedure. The stability analysis, exercised only once, uses a modification of the Gibbs tangent plane criterion. The identification procedure implements the results of the stability test in a sequence of liquid‐liquid and liquid‐vapor calculations only till the phase configuration with a minimum Gibbs energy is determined.The efficiency and reliability of the proposed new method is illustrated by solving three typical problems encountered in enhanced oil recovery, natural gas processing and petrochemical industry.
In‐situ extraction and purification of ethanol using commercial oleic acid
Authors: Jassal D. S. , Zhang Z. , Hill G. A. 
Published: March 2009

AbstractThe flash process for the removal of ethanol from commercial oleic acid has been experimentally studied and modelled using a modified Redlich‐Kwong‐Soave equation of state (RKAES) and the ASPEN process simulator. Using feed ethanol and water concentrations spanning the range of expected liquid‐liquid extraction concentrations, it was found that 93.6% by weight of ethanol in the distillate was obtained consuming only 2 MJoules of energy per kilogram of ethanol recovered. The RKAES model was found to reasonably predict the ethanol recovery and purity with errors under 5%. Commercial oleic acid was found to be completely non‐inhibitory towards the growth of Saccharomyces cerevisiae cells when used for in‐situ extraction at a concentration of 50% of the total fermenter volume.
Separation of strong acids by electrodialysis with membranes selective to monovalent ions. An approach to modelling the process
Authors: Andrés L. J. , Riera F. A. , Alvarez R. , Audinos R. 
Published: March 2009

AbstractIn this work some mixtures of sulphuric and nitric acids have been separated and concentrated by selective electro‐dialysis (SED) using heterogeneous membranes. Selective membranes can now be used for the separation of acids since anion exchange membranes with reduced transport number to multivalent ions are commercially available. The electric performance of the system has been analyzed and a correlation between current density, hydrodynamic parameters and concentration was established. The modelling of the SED experiments can be achieved with a good fitting for various membrane configurations of industrial interest.Experimental results show that at operation times lower than 40 minutes, the selective anion exchange membranes efficiently exclude the sulphate anions. The nitrate anions fall to zero concentration at 60 minutes of operation and then the sulphate anions begin to cross through the membrane.
Hydrogenation of (—)‐α‐pinene over nickel—phosphorus/aluminum oxide catalysts prepared by electroless deposition
Authors: Ko Sun‐Hua , Chou Tse‐Chuan 
Published: March 2009

AbstractLiquid‐phase hydrogenation of (—)‐α‐pinene was investigated using a new type of amorphous nickel‐phosphorus catalyst supported on aluminum oxide. The catalyst was prepared by the electroless deposition of nickel on the solid support at atmospheric pressure and moderate temperature from an aqueous solution. Two types of supports, aluminum oxide powder and pellet, were used. Electron probe micro‐analysis (EPMA) indicated that the nickel profile on the aluminum oxide powder was uniform throughout the whole particle of the powdery support; however, the nickel deposition on the catalyst supported by pellet aluminum oxide exhibited an eggshell‐type profile with a thickness about 8 μm. The amorphous structure of the nickel was confirmed by X‐ray diffraction (XRD). The procedure by which the catalysts were prepared involved four steps: etching, sensitization, activation and deposition. The conditions employed for the sensitization, activation and deposition steps significantly affected the composition, structure, metal profile and activities of the catalysts. Etching, however, had a negligible effect on the properties of the catalysts. Very high selectivity was found for hydrogenation of (—)‐α‐pinene to cis‐pinane.
Performance of control strategies to track the trajectories of batch reactors
Authors: Chang Jyh‐Shyong , Huang Kuang‐Li 
Published: March 2009

AbstractWe propose a modified globally linearizing control (MGLC) structure and a nonlinear feedforward‐feedback control (NFF/FB) structure to track trajectories of processes in a batch reactor. The MGLC structure performs trajectory tracking perfectly when the model inversion can be obtained by linearization of state feedback. Otherwise, the NFF/FB structure is recommended. The performance of the control laws that we developed are compared with other control laws designed with the same technique. The proposed control law based on the MGLC structure exhibits robust performance whereas that based on NFF/FB structure produces decreased sensitivity to process noise.
Effect of feed cycling on plasmid stabilization during continuous fermentation: The case of variable plasmid loss probability
Authors: Patnaik P. R. 
Published: March 2009

AbstractThe effect of feed cycling on the stability of plasmid‐bearing cells during continuous fermentation has been analysed for the case where the probability of loss of the plasmid varies with time. The model consists of a system of delayed differential equations. By using a square‐wave profile of the dilution rate, a two‐fold increase in the concentration of plasmid‐bearing cells and the recombinant product can be achieved over what is possible with a constant dilution rate. The dilution rate has a stronger effect than the frequency. These results agree qualitatively with reported experiments. The plasmid loss probability and the differential growth rate show fluctuations for a square‐wave variation in the dilution rate, and even with a constant dilution rate they stabilise only after a length of time. These observations show that it is particularly important to account for variable plasmid loss probability in the initial phase of fermentation.
Transfert de chaleur dans un film tombant autour d'un cylindre horizontal
Authors: Agunaoun A. , Daïf A. , Grisenti M. , Barriol R. 
Published: March 2009

AbstractConnaissant le débit initial d'un film mince de liquide tombant sur un ou plusieurs tubes horizontaux, on propose un modèle de calcul permettant la détermination des coefficients de transfert de chaleur locaux. Ce travail est effectué pour des nombres de Reynolds inférieurs à 2000 et pour un flux ou une température constant. Le modèle prend en compte non seulement les effets convectifs mais aussi la courbure de l'interface liquide‐vapeur. On évalue globalement la partie du film évaporée après son passage sur la surface d'échange. Les résultats de ce modèle montrent que dans le cas où le flux de chaleur pariétal est imposé, ce dernier n'a pas d'influence sur la valeur du coefficient d'échange. La prise en compte de la courbure de l'interface permet un meilleur accord avec l'expérience, en particulier en ce qui concerne l'évaluation du nombre de Nusselt moyen quand le nombre de Reynolds est supérieur à 1000.
Estérification de l'acide stéarique par des alcools légers: Catalyse homogène par les titanates
Authors: Nasr Elsayed , Guiraud Roland , Pellegatta Jean Louis , Blandy Claudine 
Published: March 2009

AbstractL'estérification de l'acide stéarique par des alcools à bas points d'ébullition en présence de titanates, est réalisée dans un réacteur semi‐continu. L'étude cinétique de la réaction à haute température (condition où les titanates sont le plus efficaces), nécessite la prise en compte de la réaction non catalysée. L'intérět du catalyseur est précisé; la nature de l'espèce active qui dépend de réactions d'échanges très rapides est aussi discutée.
Optimum designs of longitudinal fins
Authors: Yeh Rong‐Hua 
Published: March 2009

AbstractEmploying fin parameter and tip temperature, a new concept with Lagrange's multiplier method is proposed to obtain the optimum width, height, heat dissipation, and efficiency of longitudinal fins for boiling heat transfer. A power‐law type heat transfer coefficient is assumed in this analysis. Longitudinal fins of rectangular, convex parabolic, triangular, and concave parabolic profiles are first investigated. It is found that the optimum dimensions of a fin depends upon fin profile area, heat transfer coefficient at the fin base, and the thermal conductivity of the fin. Then, the least material fin profile is derived for each single heat transfer mode. To facilitate the thermal design of heat transfer components, simple mathematical expressions for the optimum dimensions of fins are presented in this study.
Studies on the effects of various design and operational parameters on solid circulation rate in a recirculating fluidized bed
Authors: Alappat Babu J. , Rane V. C. 
Published: March 2009

AbstractEffects of various operational parameters, such as draft tube superficial air velocity and solid inventory and design parameters such as jet diameter and clearance between perforated plate and draft tube bottom on the solid circulation rate of a recirculating fluidized bed are studied. A simple butterfly valve arrangement was used for the direct measurement of the solid circulation rate.
Bubble size and velocity measurement in gas—liquid systems: Application of fiber optic technique to pilot plant scale
Authors: Saberi S. , Shakourzadeh K. , Bastoul D. , Militzer J. 
Published: March 2009

AbstractA new fiber optic probe was developed for the detection and measurement of bubble sizes and velocities in a gas‐liquid column. The probe is made of a single 1 mm plastic fiber with a sharp wedge tip. The calibration was carried out on a laboratory scale unit using a cine‐photographic technique to verify the measurements. Bubble velocities were calculated using two identical parallel fibers and the cross‐correlation technique. With the velocities and the passage time determined, it was then possible to determine the bubble diameter. Bubble diameters were within 10% of the measurements obtained with the cine‐photographic technique. After calibration, measurements were carried out on a pilot scale unit.
Mass transfer from highly soluble cylinders in cross flow: Some experimental results
Authors: Lohia P. K. , Narayan K. A. , Chhabra R. P. 
Published: March 2009

AbstractMass transfer coefficients from highly soluble cylinders in cross flow orientation have been determined experimentally. The separate contributions arising from the different parts of the cylinder, namely, the front, plane sides and the rear have been delineated by masking various parts of the test specimen. Simple empirical expressions are devised for the components as well as for the total mass transfer coefficient. The present results compare favourably with the literature data in the following ranges of conditions: 90 ≤ Rep ≤ 850; 600 ≤ Sc ≤ 1100 and 70 ≤ Sh < 210.
Critical impeller speed for solid suspension in multi‐impeller three phase agitated contactors
Authors: Dutta N. N. , Pangarkar V. G. 
Published: March 2009

AbstractThe critical impeller speed for solid suspension in gas‐liquid‐solid systems has been measured in multi‐impeller agitated contractors of 0.15 and 0.30 m and ID and 1.0 m height. Three types of impellers, i.e. disk turbine (DT), pitched turbine downflow (PTD) and pitched turbine upflow (PTU) were used. Air, deionised water and sand particles were used as the gas, liquid and solid phases, respectively. The superficial gas velocity and solid loading were varied in the ranges 0–15 mm/s and 0.5 to 10% w/w, respectively. The effects of impeller type and its diameter, particle size and loading and gas flow rate were studied. Some measurements of gas hold‐up and mixing time were also made in order to get some insight of the hydrodynamic behaviour of the reactor. The critical impeller speed for solid suspension in the presence of gas (nisg) was found to be more than that in the absence of the gas and the increase of critical speed correlated well with the gas flow rate. The influence of particle—liquid parameters on solid suspension speed in the gassed system was similar to but relatively weaker than that in the ungassed condition.
Tailoring Disorder and Dimensionality: Strategies for Improved Solid Oxide Fuel Cell Electrolytes
Authors: Garcia‐Barriocanal Javier , Rivera‐Calzada Alberto , Varela Maria , Sefrioui Zouhair , Díaz‐Guillén Mario R. , Moreno Karla J. , Díaz‐Guillén José A. , Iborra Enrique , Fuentes Antonio F. , Pennycook Stephen J. , Leon Carlos , Santamaria Jacobo 
Published: March 2009

AbstractTowards cooler solid oxide fuel cells: Disorder and dimensionality (see picture) play an important role in determining ion mobility of bulk and artificially nanolayered materials and should be considered in the design of new electrolytes with enhanced conductivity.magnified imageReducing the operation temperature of solid oxide fuel cells is a major challenge towards their widespread use for power generation. This has triggered an intense materials research effort involving the search for novel electrolytes with higher ionic conductivity near room temperature. Two main directions are being currently followed: the use of doping strategies for the synthesis of new bulk materials and the implementation of nanotechnology routes for the fabrication of artificial nanostructures with improved properties. In this paper, we review our recent work on solid oxide fuel cell electrolyte materials in these two directions, with special emphasis on the importance of disorder and reduced dimensionality in determining ion conductivity. Substitution of Ti for Zr in the A2Zr2−yTiyO7 (A=Y, Dy, and Gd) series, directly related to yttria stabilized zirconia (a common fuel cell electrolyte), allows controlling ion mobility over wide ranges. In the second scenario we describe the strong enhancement of the conductivity occurring at the interfaces of superlattices made by alternating strontium titanate and yttria stabilized zirconia ultrathin films. We conclude that cooperative effects in oxygen dynamics play a primary role in determining ion mobility of bulk and artificially nanolayered materials and should be considered in the design of new electrolytes with enhanced conductivity.