bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of solid particles in liquid fluidized beds
Authors: Patwardhan V. S. , Tien Chi 
Published: March 2009

AbstractA method is proposed for calculating the steady‐state distribution of mixtures of solid particles and of the axial bed porosity in liquid fluidized beds. The extent of bed stratification is assumed to be determined by the differences among the settling velocities of the fluidized particles and the random motion of these particles that is a result of fluidization. Predictions of particle distribution based on the present method were found to agree reasonably well with experimental data.
Destabilization of fluidized beds due to agglomeration part I: Theoretical model
Authors: Tardos Gabriel , Mazzone Dominick , Pfeffer Robert 
Published: March 2009

AbstractThis is the first part of a series of two papers to study the agglomeration phenomenon which causes destabilization of certain low and high temperature fluidized beds. A theoretical model is proposed to determine the conditions under which defluidization occurs in fluidized beds in which cohesion forces between granules arise due to the presence of sticky fluids and/or high temperatures. Such bonding mechanisms between particles as solid—liquid bridges, visco‐elastic flattening and high temperature sintering are considered. The theoretical model predicts breakup of aggregates in the bed due to forces generated by bubble motion. The theoretical results are compared with experimental measurements in Part II of the paper.
Destabilization of fluidized beds due to agglomeration part II: Experimental verification
Authors: Tardos Gabriel , Mazzone Dominick , Pfeffer Robert 
Published: March 2009

AbstractThe limiting fluidization‐defluidization condition for fluidized beds of sticky particles has been studied experimentally in both low temperature beds in which defluidization occurs due to the presence of sticky fluids and in high temperature beds where agglomeration occurs due to sintering of the granules. The experimental results described herein as well as others taken from the literature are compared to the predictions of the theoretical model developed in Part I of this paper.
Fed‐batch production of cellulases using trichoderma reesei rutgers c‐30
Authors: McLean David D. , Abear Kim , Podruzny M. Faye 
Published: March 2009

AbstractIn the past ten years there has been considerable attention devoted to improving the microbial production of cellulases for their potential in saccharification of cellulosic materials. The Rut. C‐30 strain of the fungus Trichoderma reesei has yielded some of the best enzyme activities and productivities reported to date. The use of fed‐batch techniques has also been shown to improve enzyme productivities while maintaining or increasing enzyme activities and reducing problems associated with aeration, mixing and foaming. In this work on fed‐batch production of cellulases using Rut. C‐30 the effects of both the size of the substrate injection and the time between injections are examined. The results indicate an appropriate feeding policy and provide insight into the mechanism for cellulase production.
Forced convection heat transfer from axisymmetric bodies to non‐Newtonian fluids
Authors: Shenoy A. V. , Nakayama A. 
Published: March 2009

AbstractA theoretical analysis for forced convection heat transfer from axisymmetric bodies immersed in non‐Newtonian power‐law fluids has been performed. Results for the velocity shape factor, local friction coefficient, and the Nusselt number are presented for different values of Prandtl number and the power‐law index. The local friction coefficient results are compared with available experimental data and it is shown that asymptotic expressions suffice to get accurate predictions of heat transfer at low and high Prandtl numbers.
A correlation for gas holdup in turbulent coalescing bubble columns
Authors: Reilly I. G. , Scott D. S. , De Bruijn T. , Jain A. , Piskorz J. 
Published: March 2009

AbstractA review of existing literature for the purpose of comparing correlations which allow the explicit predictiosn of gas holdup in two‐ or three‐phase bubble columns shows wide disagreement concerning the effect of various variables. Further, various correlations, apparently of equal validity, show equally wide disagreement in the predicted absolute values of gas holdup among three test systems; water‐air, hydrocarbon solvent—air, and trichloroethytene air. Some possible reasons for these disagreements are discussed.Extensive gas holdup data obtained in a 0.30 m diameter column for the three test systems were correlated statistically for the transition and the turbulent region. The resulting correlation gives agreement with experiment to within ±20%, with most data showing ± 10% agreement. The proposed correlation was also tested against thirteen data sets (from eight researchers) which corresponded to its region of validity and gave good agreement. Three additional relevant data sets were not satisfactorily predicted.
Creeping motion of a carreau fluid past a newtonian fluid sphere
Authors: Chhabra R. P. , Dhingra S.C. 
Published: March 2009

AbstractPrevious work on the slow motion of drops in non‐Newtonian liquids has been reviewed. The variational principles have been employed to obtain approximate upper and lower bounds on drag force experienced by a fluid sphere moving slowly in Carreau model fluids. The paper is concluded by presenting a comparison with the appropriate experimental data available in the literature.
Pipeline flow behaviour of heavy crude oil emulsions
Authors: Wyslouzil B. E. , Kessick M. A. , Masliyah J. H. 
Published: March 2009

AbstractPipeline transportation of heavy oils as oil‐in‐water emulsions has been proposed as an alternative to blending the crude oil with natural gas condensate or other diluent. An 18 m long, 0.02 m I.D. closed loop was constructed to investigate the behaviour of an emulsified Cold Lake crude oil under pipeline flow. Pressure drop was measured as a function of flow rate for freshly produced emulsions to establish correlations of friction factor versus Reynolds number. Stability was observed for long term pipeline flow. The time at which the emulsion breakdown occurred was found to be a function of oil concentration and shear rate. The breakdown of the emulsion was clearly indicated by a simultaneous change in the system variables of pressure drop, temperature and power required to turn the pump at constant speed.
Drag and mass transfer in a creeping flow of a carreau fluid over drops or bubbles
Authors: Jarzebski Andrzej B. , Malinowski Janusz J. 
Published: March 2009

AbstractEstimates for the upper bound on the drag coefficient for a single drop or bubble or a swarm of drops or bubbles translating in a Carreau fluid are obtained using variational principles. The effects of a wide range of shear thinning properties, holdup and viscosity ratios on drag and mass transfer rate are discussed. Recently published predictions of approximate analytical solutions are verified and found to be reasonable if shear thinning behaviour is not pronounced.
Kraft black liquor recovery in a fluidized bed: Part I — A review
Authors: Fallavollita J. A. , Mujumdar A. S. , Avedesian M. M. 
Published: March 2009

AbstractThe Tomlinson recovery boiler has been the mainstay of the kraft pulping industry for over fifty years. It is clear, however, that the main drawbacks to this process are the large capital costs of new plant and the smelt‐water explosion hazard.This paper examines some of the fundamental scientific information which supports the concept of fluid bed gasification as an alternative to the Tomlinson boiler. It is shown that a knowledge of thermodynamics is useful but insufficient to completely understand the behaviour of the inorganic sulfur species during pyrolysis and gasification of kraft black liquor. Recent key experimental investigations at McGill have demonstrated that solid state reduction of sodium sulfate to sodium sulfide is feasible.
Pretreatment of wood flour slurries prior to liquefaction
Authors: Vanasse C. , Lemonnier J. P. , Eugène D. , Chornet E. , Overend R. P. 
Published: March 2009

AbstractAs part of the UDES‐S solvolytic approach to wood fractionation and liquefaction, a pretreatment stage has been developed using a fed batch technique to produce high solids content slurries. By using a combination of temperature and shear stress across homogenizing valves, wood flour slurries of Populus spp having concentrations of 20‐32% by weight in both paraffin oil and ethylene glycol have been produced. Optical and scanning electron microscopy have shown that the recirculation loop and homogenizing valve cause structural degradation, defibration and defibrillation of the original particles as well as partial solubilization of the wood components. The maximum wood flour concentration, attainable before plugging was observed in the small scale system used, was just below 36% by weight. High concentration slurries are a prerequisite in order to obtain realistic reactor space velocities in biomass liquefaction processes.
Modified oil agglomeration process for coal beneficiation. II. Simultaneous grinding and oil agglomeration
Authors: Trass Olev , Bajor Oliver 
Published: March 2009

AbstractThe spherical oil agglomeration technique developed at the National Research Council of Canada (NRC) for cleaning and recovering very small coal particles can be simplified by combining the grinding and agglomeration steps such that the excess energy expended while grinding is used for mixing and agglomeration. Experiments with the Szego mill, which is able to handle the pasty agglomerates, have shown that ash removal from Minto (New Brunswick) coal is comparable to that obtained with the usual NRC process. The generally flaky products of the Szego mill allow better ash liberation, and the presence of oil enhances grinding performance. Favourable oil‐coal‐water ratios have been established. Major savings in equipment and operating costs are possible with the combined process.
Particle‐liquid mass transfer in three phase sparged reactor
Authors: Jadhav S. V. , Pangarkar V. G. 
Published: March 2009

AbstractParticle‐liquid mass transfer in a three phase sparged reactor has been studied over a wide range of particle sizes, for the chum‐turbulent regime. The particle‐liquid Sherwood number has been correlated in the usual form with the Reynolds and Schmidt numbers. Use of the hindered particle settling velocity in the Reynolds number yields good agreement (±20%) with the present as well as most of the literature data. The proposed correlation also holds for power law non‐Newtonian liquids when the effective viscosity is used.
A modified correlation to predict the minimum velocity required to elutriate solids from a liquid‐fluidized bed
Authors: Ganguly U. P. 
Published: March 2009

AbstractThe consideration of sphericity of solids for the prediction of ume gives rise to some improvement of the correlation proposed earlier by the author. In the absence of wall‐effect, the following correlation is obtained:

which gives a standard deviation of ± 16.3% for 138 different experiments as against ± 21.6% for 134 runs by the correlation reported earlier. The ranges of the various groups are
The measurement of instantaneous local heat transfer coefficients in a circulating fluidized bed
Authors: Wu R. L. , Lim C. J. , Grace J. R. 
Published: March 2009

AbstractInstantaneous and time‐averaged local bed‐to‐wall heat transfer coefficients were measured in a 9.3 m tall, 152 mm ID cold model circulating fluidized bed riser at three different heights for 171 μm Ottawa sand at a superficial gas velocity of 7 m/s, and for solids circulation fluxes up to about 70 kg/m2.s. All data were obtained with an instantaneous heat transfer probe consisting of a thin platinum film deposited on a 1 cm2 piece of glass protected by a thin plastic film. Instantaneous heat transfer coefficients in the riser showed sudden and dramatic peaks caused by strands or sheets of particles sweeping past the probe. Consistent with previous work, time‐averaged coefficients varied nearly linearly with suspension density. The heat transfer coefficient decreased from the bottom to the middle of the column, and then increased near the top due to an increase in suspension density for the exit geometry employed.
Modelling the internal flow structure of circulating fluidized beds
Authors: Berruti Franco , Kalogerakis Nicolas 
Published: March 2009

AbstractA simple hydrodynamic model for Circulating Fluidized Beds has been developed. The mathematical model, based on the core‐annulus flow structure, is shown to be able to predict the two‐phase flow characteristics and it requires only two measurable steady‐state parameters, namely the experimental average voidage profile along the riser, or equivalently the pressure distribution, and the net solids circulation rate. The model has been successfully tested using recently obtained literature data covering a variety of reactor configurations and operating conditions.
On the possibility of general prediction of gas hold‐up in reciprocating plate columns
Authors: Veljkoviĉ V. B. , Skala D. U. 
Published: March 2009

AbstractGas hold‐up was measured in a 2.54 cm diameter reciprocating plate column for countercurrent flow of air and tap water. The gas hold‐up data obtained could not be correlated by the relationship based on slip velocity, modified for circulation effects, as proposed by Rama Rao and coworkers. An analysis using other gas hold‐up data available in the literature, obtained in reciprocating plate columns of different sizes and geometries, confirmed that this relationship could not be used for the general prediction of gas hold‐up in this type of gas‐liquid contactor.
Air entrainment and dynamic contact angles in hydrodynamics of liquid coating
Authors: Esmail M. N. , Ghannam M. T. 
Published: March 2009

AbstractThe dynamic contact angles and the phenomenon of entrainment of air bubbled in liquid coating processes are investigated by experimental measurements in which liquid viscosity was varied. The technique consists of using a continuously rotating liquid roller, which is submerged in a liquid pool. The test liquids are glycerol solutions with viscosities in the range 197 < μ < 748 mPa.s. The capillary length (σ/ρg)½ is used as a characteristic dimension. The dynamic contact angle is shown as a function of the capillary number and physical properties number. Dimensional correlations for air entrainment criteria are reported for moderate capillary numbers Ca < 2.
Particle velocity and solids circulation rate in a jet‐spouted bed
Authors: Uemaki Osamu , Tsuji Toshiro 
Published: March 2009

AbstractRadial distribution of particle velocities, solids circulation rate and radial variation in bed voidage in a jet‐spouted bed were investigated in a 0.2 m diameter conical‐cylindrical column. The upward particle velocity is strongly dependent on gas velocity and its radial profile is the Gaussian. The solids circulation rates are of the same order of magnitude as those in a conventional spouted bed and are proportional to the gas velocity. Estimation of the variation in bed voidage in the radial direction revealed that the annulus voidage of about 0.90 was greater than the spout voidage of around 0.70. This tendency is contrary to that in a conventional spouted bed.
Oxygen absorption in a baffled tank agitated by delta paddle impeller
Authors: Baird M. H. I. , Rama Rao N. V. , Shen Z. J. 
Published: March 2009

AbstractThe power consumption and the volume‐based mass transfer coefficient (kla) for oxygen uptake from air into water have been measured for delta paddle impellers (10 cm and 20 cm diameter) in water in a 30 cm square sectioned baffled tank. Power consumption under ungassed conditions was measured in viscous mineral oil. For the 20 cm impeller, the effects of minor design modifications, such as sweeping the blade forward or back, have also been examined. The power numbers are approximately 2.0 in the absence of sparged gas, but are reduced by over 50% when gas is supplied beneath the impeller. Mass transfer data can be correlated with the power input per unit volume and the superficial gas velocity, showing that the performance with aeration of water is comparable to that reported by previous workers for the Rushton turbine impeller.
Drying paper by impinging jets of superheated steam. Part 2: Comparison of steam and air as drying fluids
Authors: Bond J. F. , Mujumdar A. S. , van Heiningen A. R. P. , Douglas W. J. M. 
Published: March 2009

AbstractThe behavior of superheated steam and air as drying fluids during the constant rate period of drying paper under impinging jets was compared in the jet temperature range 20 ≤ Tj 465°C for jet Reynolds numbers of l000 ≤ Rej ≤ 12000. At equal mass flux, steam drying is faster than air drying above the inversion temperature of 175°C. Also, the specific blower power for steam drying is much lower than for air drying at temperatures in the range of industrial importance. Superheated steam impingement drying can therefore lead to important capital investment and energy cost reductions, relative to air drying.
Further studies on flowing gas‐solids suspensions in a tube at high angles of inclination
Authors: Ginestet A. , Guigon P. , Large J. F. , Beeckmans J. M. 
Published: March 2009

AbstractThe flow of glass (0.571 mm) and canola seed (1.75 mm) particles entrained by air in a 31.8 mm i.d. conduit inclined at 72° or at 90° to the horizontal was studied. With glass particles a transition between a dilute and a dense phase was found at both orientations, but no transition point was found with canola seed particles. Plots of solids volume fraction versus solids flux in the dilute regime were curved, implying interparticle interactions were significant even at very low solids volume fractions. The velocity of canola seed particles in admixture with sand particles (0.186 mm) increased as the proportion of sand in the mixture increased. Finally, it was found that the oily film imparted by the canola seed particles to the sand particles significantly affected the behaviour of the sand particles in the dense regime.
Effect of pore size on bitumen hydrocracking over Al2O3‐AlPO4 supported Ni‐Mo catalysts
Authors: Smith Kevin J. , Lewkowicz Leszek , Oballa Mike C. , Krzywicki Andrzej 
Published: March 2009

AbstractA study of co‐precipitated aluminum oxide‐aluminum phosphate (AAP) materials as supports of Ni‐Mo heavy oil upgrading catalysts has been completed. Results of both short duration (8 h) and longer duration (up to 200 h) experiments at conditions relevant to the commercial H‐Oil process are reported and compared with a commercial NiMo/Al2O3 catalyst.The initial activity of the Ni‐Mo/AAP catalysts correlates with the catalyst average pore diameter which is determined by the P content of the AAP support. An optimum pore diameter of about 20 run exists for HDM whereas for HDS a pore diameter < 10 nm is desirable. After 100 h operation the HDM conversion of the best Ni‐Mo/AAP catalyst was approximately 10 percentage points greater than for the commercial catalyst. The HDS and CCR conversions were comparable over the two catalysts. The difference in performance between the catalysts is attributed primarily to the smaller pore size of the Al2O3 support compared to the AAP support. The amount of coke deposited on the Ni‐Mo/AAP catalyst was less than that on the commercial catalyst, presumably due to differences in pitch conversion levels.
Spirituality and health: a knowledge, attitude and practice study among doctors of North India
Authors: Bansal Rahul , Maroof Khan Amir , Parashar Pawan , Pant Bhawna 
Published: March 2009

AbstractA cross‐sectional study was conducted among doctors of North India (n = 250) with the help of self‐administered questionnaire. The mean age of doctors was 42.18 years (standard deviation = 9.108). Of the total respondents, 74.35% were male and 25.65% were female; 65.65% had a strong or very strong belief in the spiritual dimension of health; 55.22% believed in the preventive role of spirituality; 80% believed in the curative role of spirituality and a similar proportion held the view that spirituality has an important role in day‐to‐day patient care; and 92.5% wanted to know more about the scientific work being done in the field of spirituality. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of environmental allergen sensitization on asthma morbidity in inner‐city asthmatic children
Authors: Wang J. , Visness C. M. , Calatroni A. , Gergen P. J. , Mitchell H. E. , Sampson H. A. 
Published: March 2009

SummaryBackground
Asthma causes significant morbidity in children, and studies have demonstrated that environmental allergies contribute to increased asthma morbidity.Objective
We investigated the differences between allergen skin tests and specific IgE (SIgE) and the role of IgG in regards to allergen exposure levels, and asthma morbidity in inner‐city children.Methods
Five hundred and six serum samples from the National Cooperative Inner City Asthma Study (NCICAS) were evaluated for SIgE to cockroach (Blattella germanica), dust mite (Dermatophagoides farinae), and Alternaria as well as specific IgG (SIgG) and IgG4 to cockroach (B. germanica) and total IgE levels. Associations between sensitization to these allergens, exposures, and asthma morbidity were determined.Results
Sensitization to environmental allergens and total IgE correlated with increased health care and medication use, but not with symptoms of wheeze. Sensitization with exposure to cockroach was associated with increased asthma morbidity, whereas dust mite sensitization was correlated with asthma morbidity independent of exposure. There was also a strong correlation between SIgE levels and skin test results, but the tests did not always agree. The relationship between SIgE and asthma morbidity is linear with no obvious cutoff value. Increased Bla g 1 in the home was a good predictor for sensitization; however, this relationship was not demonstrated for Der f 1. Cockroach SIgG correlated with increased health care use, however, there was no modifying effect of SIgG or SIgG4 on the association between cockroach SIgE and asthma morbidity.Conclusions
SIgE levels and skin prick test results to environmental allergens can serve as markers of severe asthma for inner‐city children. Asthma morbidity increased in a linear manner with SIgE levels. IgG was not an important predictor or modifier of asthma morbidity.
Characterization of polymorphic microsatellite loci in the marine isopod Sphaeroma terebrans (Crustacea, Isopoda)
Authors: BARATTI MARIELLA , FILIPPELLI MARIATERESA , MESSANA GIUSEPPE , PAPETTI CHIARA , PATARNELLO TOMASO , ZANE LORENZO 
Published: March 2009

AbstractNine polymorphic microsatellites were characterized in the marine isopod Sphaeroma terebrans (Isopoda, Sphaeromatidae) for phylogeographic and parentage analyses. The number of alleles ranged from 3 to 10. Observed heterozygosity ranged from 0.428 to 0.950, while expected heterozygosity ranged from 0.532 to 0.889. Heterozygote deficiency was detected for one locus, possibly the result of null alleles.