bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid mass transfer in laminar flow in a column containing a string of spheres and cylinders
Authors: Sotelo J. L. , Benitez F. J. , Cabrera L. 
Published: March 2009

AbstractThe absorption of carbon dioxide by aqueous glycerine solutions in a column containing a string of spheres and cylinders has been studied. The Reynolds number was varied between 5 and 560. Using a model based on Higbie's penetration theory, modified to fit the characteristics of this absorber, the number of surface renewals that takes place in the column has been evaluated and correlated with the operating variables that can influence it. The liquid viscosity has no influence on the surface renewal which depends mainly on the liquid rate.
La—Ni system porous anode in an alkaline fuel cell
Authors: Tanaka H. , Kaneki N. , Hara H. , Shimada K. , Takeuchi T. 
Published: March 2009

AbstractLa—Ni system alloys in fine powder form were used to make the hydrogen electrode for an alkaline fuel cell. LaNi5 electrodes were found to have the highest electrode performance among the La—Ni system electrodes. Using LaNi5 powder of mean particle size 3.4 μm for the electrode, the limiting current density was 180 mA/cm2. However mixing the same size powder (mean particle size 3.4 μm) with powder of mean particle size 40.5 μm in a ratio of 4:1, the limiting current density of the new electrode was 250 mA/cm2. The electrode was found to have both relatively fine pores in the range 0.01–0.2 μm and relatively large pores in the ranges 0.5–1 μm and 4–5 μm. Thus, it was found that not only relatively fine pores but relatively large pores had an important effect upon the LaNi5 electrode characteristics.
Hydrocracking of n‐heptane. Study of NiO—MoO3 catalysts supported on a HY ultrastable zeolite
Authors: Vázquez M. I. , Escardino A. , Aucejo A. , Corma A. 
Published: March 2009

AbstractThe hydrocracking of n‐heptane in the temperature range of 573 to 623 K and at 2.45 × 106 Pa pressure has been employed as a test reaction for the study of Ni—Mo bifunctional catalysts supported on a HY ultrastable zeolite.Two groups of catalysts containing 8 and 12 wt% of MoO3 and different amounts of NiO have been studied. In both series a maximum in the activity has been obtained for catalysts with a Ni/Mo atomic ratio of 0.8‐1.0. The order of the impregnation of the oxides can have little influence on the activity. The most active catalyst has been obtained when the zeolite is exchanged with NH+4 ions until the Na+ level is less than 2% of the original and calcined at 823 K to obtain a HY ultrastable zeolite. Using this catalyst the rate controlling step could be the transformation of the carbonium ion on the acid sites.
Catalytic conversion of canola oil to fuels and chemical feedstocks: Part II Effect of co‐feeding steam on the performance of HZSM‐5 catalyst
Authors: Prasad Y. S. , Bakhshi N. N. , Mathews J. F. , Eager R. L. 
Published: March 2009

AbstractCa lola oil and steam were co‐fed continuously to a 15.5 mm i.d. fixed‐bed reactor loaded with HZSM‐5 catalyst at varying process conditions. The liquid hydrocarbon product contained 60–70 wt% aromatics. The gas product was highly olefinic, while for canola oil alone it was mostly paraffinic. The C2‐C5 olefin selectivity increased with an increase in the steam/canola oil ratio in the feed. In addition, co‐feeding with steam resulted in a two‐fold increase in the catalyst life. Though the exact role of steam in altering the chemistry of the reaction is not known, it is probable that the rates of olefin formation and aromatization reactions are affected by the presence of steam. The product pattern suggests the possibility of propene being the initial olefin in the reaction scheme.
Catalytic effect of mineral matter of high ash onakawana lignite on steam gasification
Authors: Furimsky Edward 
Published: March 2009

AbstractReactivities of untreated and acid washed Onakawana lignite during steam gasification were compared in a thermo‐balance reactor. The acid treatment resulted in removal of Ca, Mg, Ba and Sr from mineral matter. This was accompanied by a marked decrease in the rates of H2, CO and CO2 formation. The decrease of gasification rate was attributed to the decrease in concentration of gasification sites during the acid treatment.
Erosion and thermal shock tests on ceramic materials
Authors: Whiteway S. G. , Chan E. W. , Kazi A. 
Published: March 2009

AbstractThe resistance to erosion and thermal shock of several ceramic materials, particularly alumina, was measured. The alumina specimens were made by pressing and sintering finely ground particles. The objective was to fabricate wear‐resistant components for a burner assembly used for the atomization and combustion of abrasive coal‐liquid fuels. The test procedures are described, and their use demonstrated to identify a commercially available material from which shapes were prepared to a dimensional accuracy of 0.5%, of 99.5% theoretical density, and having optimized erosion and thermal shock resistance.
PRSV: An improved peng—Robinson equation of state for pure compounds and mixtures
Authors: Stryjek R. , Vera J. H. 
Published: March 2009

AbstractThe temperature and acentric factor dependence of the attractive term of the Peng—Robinson equation of state have been modified. The introduction of a single pure compound parameter allows the accurate reproduction of the vapor pressure data for a wide variety of substances. Nonpolar, polar nonassociating and associating compounds are equally well represented by the cubic PRSV equation of state. The conventional one‐binary‐parameter mixing rule allows the correlation of the vapor—liquid equilibrium data for a wide variety of binary systems. Only for systems formed by a polar compound (associating or not) and a saturated hydrocarbon, are results poorer than those obtained with conventional excess Gibbs energy functions.
PRSV — An improved peng‐Robinson equation of state with new mixing rules for strongly nonideal mixtures
Authors: Stryjek R. , Vera J. H. 
Published: March 2009

AbstractTwo new composition dependent mixing rules for cubic equations of state are proposed. Both mixing rules contain two adjustable binary parameters and reduce to the conventional one parameter mixing rule when the parameters are equal. Vapor‐liquid equilibrium data for mixtures of polar (associated or not) compounds with saturated hydrocarbons and for systems water/alcohol have been used to test the new mixing rules applied to the PRSV cubic equation of state. For these highly nonideal systems, correlation of the data with a new mixing rule of the Van Laar type for the PRSV equation gives better results than those obtained using excess Gibbs energy functions like the Wilson equation, NRTL and UNIQUAC.
Probe for measuring local gas holdups in saline potash pulps
Authors: Zrymiak Tara L. , Hill G. A. 
Published: March 2009

AbstractA conductivity probe has been designed and used to measure the gas holdup at a point in both two and three phase flows of saline solutions. The probe uses a direct current voltage and acts as a simple on‐off switch. The probe is a single unit with one electrode being the probe body and the other electrode simulating a massless point.It was found that the probe gave similar gas holdup trends to the pressure drop method of measuring overall gas holdup. When used in a bubble column the probe could be used to indicate bubble sizes and corresponding rise velocities. Equations are presented which were used to convert the electric output of the probe to these physical parameters.
Adsorption of radium‐226 from solution by the container walls
Authors: Tsezos M. , Walker C. , Keller D. 
Published: March 2009

AbstractThis work quantifies the adsorptive uptake of radium‐226 from solution by the walls of the solution container. Three different container materials were examined, each with significantly different critical surface tension. Teflon was shown to be the material with the least radium‐226 adsorption capacity in the examined pH range of 2 to 10. The radium adsorption by Teflon flasks is consistent and predictable. The respective adsorption isotherm is presented. An optimum washing procedure for the Teflon flasks was also defined.
Direct contact heat transfer with phase change: Bubble growth and collapse
Authors: Raina G. K. , Wanchoo R. K. 
Published: March 2009

AbstractA theoretical expression has been presented for the prediction of the instantaneous heat transfer coefficient of a condensing two‐phase bubble. The modified form of this model predicts very well the available experimental data. Another expression, presented for the total time taken by an evaporating two‐phase drop, also gives very good agreement with the available experimental data.
Wall‐to‐bed heat transfer in liquid—solid and gas—liquid—solid fluidized beds part I: Liquid—solid fluidized beds
Authors: Muroyama K. , Fukuma M. , Yasunishi A. 
Published: March 2009

AbstractExperimental work was conducted to investigate the effect of particle size and particle density upon the wall‐to‐bed heat transfer characteristics in liquid—solid fluidized beds with a 95.6 mm column diameter over a wide range of operating conditions. The radial temperature profile was found to be parabolic, indicating the presence of a considerable bed resistance. The effective radial thermal conductivity and the apparent wall film coefficient were obtained on the basis of a series thermal resistance model.The modified Peclet number of the radial thermal conductivity decreases upon the onset of fluidization, has a minimum at a bed porosity of 0.6 to 0.7 and increases with further increase of bed porosity. The modified Peclet number decreases considerably with decreasing particle size or increasing particle density. The apparent wall heat transfer coefficient can be represented well by a Colburn j‐factor correlation over a wide range of data as follows:j′H = 0.137 Re′−0.271A close analogy is found to exist between the modified j‐factor for wall heat transfer coefficient and that for wall mass transfer coefficient, in liquid—solid fluidized beds.
Wall‐to‐bed heat transfer in liquid—solid and gas—liquid—solid fluidized beds part II: Gas—liquid—solid fluidized beds
Authors: Muroyama K. , Fukuma M. , Yasunishi A. 
Published: March 2009

AbstractWall‐to‐bed heat transfer in gas—liquid—solid fluidized beds with a cocurrent upflow was analyzed on the basis of a series thermal resistance model. The effective radial thermal conductivity and the apparent wall heat transfer coefficient were determined over a wide range of experimental conditions.The behavior of the effective thermal conductivity strongly depends on the flow mode for the three‐phase fluidized bed, directly indicating the trend of the radial liquid mixing. The modified Peclet number for the radial thermal diffusivity takes on a minimum with respect to the liquid velocity in a manner similar to that in a liquid—solid fluidized bed, but the value of the modified Peclet number decreases significantly with gas velocity. The apparent wall heat transfer coefficient can be correlated well with a Colburn type equation which at zero gas velocity reduces to the same equation as that proposed for liquid—solid fluidization, as follows:j′H = 0.137 Re′l.g−0.271
Kinetics of isotopic exchange reaction between hydrogen and water vapor over platinum supported on a hydrophobic carrier
Authors: Kawakami Koei , Takao Yuji , Kusunoki Koichiro 
Published: March 2009

AbstractThe isotopic exchange reaction between hydrogen and water vapor was studied for the temperature range 313 K to 353 K over platinum supported on hydrophobic styrene‐divinylbenzene copolymer beads, and, for comparison, platinum supported on hydrophilic alumina pellets. The hydrophobic catalyst exhibited a high activity even with the gas saturated with water vapor, whereas the hydrophilic catalyst showed maximum exchange rate at a relative humidity of approximately 0.6. The dependences of the exchange rates on relative humidity, hydrogen partial pressure and temperature were extensively examined. The combined effect of surface reaction and intraparticle diffusion on the overall exchange reaction was analyzed to explain the kinetic behavior on the hydrophobic catalyst.
Étude de l'hydrogénation sélective du cyclopentadiène sur l'aérogel Cu/Al2O3 fluidisé
Authors: Chaouki J. , Chavarie C. , Klvana D. , Pajonk G. 
Published: March 2009

AbstractCe travail évalue l'utilisation de l'aérogel Cu/Al2O3 en lit fluidisé pour l'hydrogénation sélective du cyclopentadiène. Bien qu'appurtenant au groupe C de la classification de Geldart, les particules d'aérogel Cu/Al2O3 réussissent néanmoins à fluidiser via un processus d'agglomération au‐dessus d'une vitesse critique de 0,04 m/s. Une étude cinétique de l'hydrogénation du cyclopentadiène sur cet aérogel a été effectuée dans un réacteur intégral. L'analyse numérique des données cinétiques a permis de dégager une équation de vitesse correspondant au mécanisme de Rideal—Eley où l'étape limitante est la réaction de l'hydrogène gazeux avec le cyclopentadiène adsorbé à la surface du catalyseur. À cause de la faible activité du catalyseur, plusieurs modèles de comportement de réacteur (homogènes ou hétérogènes) peuvent décrire de manière adéquate les conversions obtenues expérimentalement dans un petit réacteur pilote à couche fluidisée. Le modèle piston idéal, plus conforme au comportement pseudo‐homogène du lit, convient cépendant le mieux statistiquement.
Feed composition modulation of hydrocarbon synthesis over a cobalt oxide catalyst
Authors: Adesina A. A. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractStudies of the Fischer‐Tropsch reaction over a cobalt catalyst under unsteady‐state conditions (i.e. both step‐change and forced feed composition cycling or feed modulation) have been carried out. Conversions were differential under conditions of atmospheric pressure and 473 K.The steady‐state rate versus feed composition curves for the alkanes were generally skewed towards the rich‐hydrogen feed compositions, while the olefins exhibited maximum steady‐state rates at the stoichiometric feed reactant ratio. The adsorption of hydrogen in the initiation step or hydrogenation of an unsaturated surface species appeared to be important in determining the alkane formation rates. The appearance of overshoot in the transient responses for some products conforms to the interpretation of a hypothesis of a succession of steady‐state rates on the surface. However, a closer examination of overshoot behaviour suggests that there is participation of carbon from within the catalyst bulk. Significant improvements found for the time‐average rates of some products were consistent with the results of the step‐change experiments.
Hydrogenolysis of n‐Hexadecane on iron and its inhibition by carbon monoxide
Authors: Monnier Jacques , Anderson Robert B. , Quilliam Michael A. 
Published: March 2009

AbstractThe hydrogenolysis of normal hexadecane was studied over iron at 325° and 355°C. As expected with iron catalysts, the main product was methane, but the selectivities for intermediate alkanes were moderately large, probably due to the length of the carbon chain. Furthermore, gas chromatography—mass spectrometry analysis of the heavier products indicated the presence of alkylbenzenes, alkenes and branched alkanes which accounted for about 20 mole % of the C9–C13 hydrocarbons. When 5.7 mole % of carbon monoxide was added to the feed, hydrogenolysis reactions were inhibited and products similar to those in the Fischer—Tropsch synthesis were found. Therefore, CO acts like a poison for the hydrogenolysis of hydrocarbons.
Experimental study on effect of elasticity on drag reduction and turbulent fluctuations in laminar‐turbulent transition region in pipe flow of dilute polymer solutions
Authors: Ogawa Kohei , Kuroda Chiaki 
Published: March 2009

AbstractBy utilizing the fact that physical properties exclusive of elasticity of dilute polyacrylamide solutions do not change with elapsed time after preparation, the effect of elasticity on drag reduction and turbulent fluctuations in pipe flow was investigated experimentally.The oscillations of axial velocity and velocity gradient and the drag reduction in the laminar‐turbulent transition region are affected significantly by the value of elasticity. The laminar‐turbulent transition region moves to a higher Reynolds number as the value of elasticity increases.
A note on the upper bound of the temperature solution of the axial dispersion model for a tubular reactor
Authors: Viljoen H. J. 
Published: March 2009

AbstractThe existing a‐priori bound of the temperature solution of the axial dispersion one‐dimensional model of the tubular reactor does not take parameters like Damköhler number into consideration. Utilizing the properties of the nonlinear term in the model equations enables one to find improved upper bounds which depend on all the model parameters. Only for the case of Lewis number greater than unity and Damköhler number sufficiently large, is the existing bound not improved.
Evaporation of volatile liquids from an open‐topped, partially filled container to an air stream
Authors: Prata A. T. , Sparrow E. M. 
Published: March 2009

AbstractExperiments were performed to measure the evaporative mass transfer from a partially filled, slot‐like container recessed in the floor of a flat rectangular duct through which turbulent air flow was passed. Toluene and cumene were used as the evaporating liquids, and systematic variations were made of the Reynolds number and of the distance between the top of the container and the surface of the evaporating liquid. The measured Sherwood numbers displayed unconventional dependences on both the Reynolds and Schmidt numbers as well as a complex dependence on the top‐to‐surface distance.
Mn and Zn doped ZSM‐5 zeolite catalysts
Authors: Mao Raymond Le Van , LÉVesque Pierre , Sjiariel Bernard 
Published: March 2009

AbstractManganese was incorporated into a ZSM‐5 zeolite by a special impregnation method which practically prevented the deposition of the metal ions on the internal surface of the zeolite pores. As a result, the production of light olefins increased sharply while that of aromatics did not significantly change. The double incorporation of Zn (by ion‐exchange) and of Mn (by this impregnation technique) led to catalysts which could produce more aromatics and more light olefins (mainly ethylene and propylene) than the parent ZSM‐5 zeolite.
Polyelectrolyte behaviour of ligninsulphonates
Authors: Bui V. T. , Hachey J. M. , Tremblay Y. 
Published: March 2009

AbstractTwo commercial ligninsulphonate samples have been investigated by means of gel permeation chromatography (GPC), viscosity, potentiometric titration and conductivity measurements. The molecular‐weight distributions given by GPC showed that the two samples consisted of a large portion of high molecular weight materials (¯w > 50 000), and a small part of low molecular weight (¯w ≃ 5000). The results obtained from titration yielded a sodium content of about 6% for both samples, and these results also confirmed that the samples do not contain any simple salts like NaHSO3 as impurity. The viscosity and conductivity data for moderate and very dilute solutions clearly demonstrated the polyelectrolyte behaviour of ligninsulphonates molecules. The equivalent conductivity at infinite dilution, Λ0, were there‐from deduced for the two samples used.
On power input and liquid‐phase mixing times in pneumatically‐agitated contactors: Response to critique of guy et al.
Authors: Robinson Campbell W. 
Published: March 2009

AbstractThe total power input to a pneumatically‐agitated gas—liquid contactor in principle is the sum of the contributions of isothermal gas expansion (p‐V work) and the changes in the potential and kinetic (ΔKE) energies of the flowing gas. The latter energy change is dependent, in part, on the pressure drop in the sparger orifices. Guy et al. (1986a) strongly infer that in practice ΔKE is never negligible compared to the p‐V work and claim that Bello et al. (1984) made a serious error in neglecting the ΔKE contribution in their cases, which error may have made their relative mixing time comparisons invalid.This communication shows that for the work of Bello et al. (1984), the ΔKE contribution was in fact negligibly small, whereas for the spargers used by Guy et al. (1986b) it was not. Furthermore, it is shown that the implication of Guy et al. (1986a) that bubble columns (BC) produce better or equivalent liquid‐phase mixing than do stirred tanks (ST) is not universally true. The relative performance of BC and ST contactors is highly dependent upon the dispersion height: diameter ratio of the former, which ratio was quite different in the works of Bello et al. (1984) and Guy et al. (1986b).
Industrial mammalian cell culture
Authors: Adamson S. R. , Schmidli B. 
Published: March 2009

AbstractA number of proteins with potential therapeutic uses (monoclonal antibodies, interferons, plasminogen activators) have been produced in mammalian cells. Novel bioreactor designs used to generate high density cultures mostly employ methods which approximate in vivo homeostasis. These perfusion and dialysis culture systems maintain the concentration of medium components and growth factors at a relatively high level while minimizing the accumulation of growth inhibitory metabolites. These methods include microcarrier culture, microencapsulation and other forms of entrapment, perfusion suspension culture in continuous stirred tank reactors, hollow fibres and combinations thereof. A summary of the status of industrial mammalian cell culture will be presented with examples illustrating the processes above.
Hydrodynamics and urea hydrolysis in a microencapsulated urease, fluidized bed reactor
Authors: Dueck C. L. , Neufeld R. J. , Chang T. M. S. 
Published: March 2009

AbstractUrease was encapsulated in ultra‐thin, semi‐permeable cellulose nitrate membranes by simple interfacial precipitation. A fluidized bed reactor was designed and constructed for containing the shear sensitive urease microcapsules. The feasibility of maintaining high conversions of urea by providing an adequate mixing regime, while eliminating the damaging effects of shear was demonstrated. A reactor productivity of 0.7 mmoles urea/sL was observed at a superficial velocity of 3.3 × 10−4 m/s using a simulated blood plasma solution. This represents a 44% conversion of urea.
Asborin: The Carbaborane Analogue of Aspirin
Authors: Scholz Matthias , Bensdorf Kerstin , Gust Ronald , Hey‐Hawkins Evamarie 
Published: March 2009

AbstractAsborin, the carbaborane analogue of aspirin, was obtained by a high‐yield synthetic procedure and proved to be an active cyclooxygenase (COX) inhibitor (H: white, B: beige, C: gray, O: blue).magnified image