ISSN:0008-4034    

DOI:10.1002/cjce.5450730102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper reviews methods for the prediction and correlation of Newtonian viscosity for pure components and mixtures of dilute gases, dense gases and liquids, focussing on those which are suited for practical engineering use. The methods reviewed were chosen because they are well known and accepted or appear potentially promising. They are categorized as theoretical, semi‐theoretical or empirical and further distinguished as predictive or correlative.Brief derivations with relevant equations and discussions on limitations and reliability of results are presented. In addition, the applicability and average deviations for each method are tabulated, with the recommended methods clearly stated. Furthermore, some gaps in viscosity prediction/correlation are identified and promising approaches are discusse

ISSN:0008-4034    

DOI:10.1002/cjce.5450730103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractUne grande controverse existe dans la littérature concemant les effets de différentes variables sur les vitesses de transition de la fluidisation turbulente. A la lumière des résultats de la littérature, quatre paramètres ont été choisis: le diamètre de la colonne, le nombre d'Archimède, la hauteur initiale du lit et la distribution de diamètre des particules. Pour caractériser l'effet de ces quatre paramètres hydrodynamiques sur la vitesse de début du régime turbulentUcet sur la vitesse de transportUtr, nous avons réalisé des expériences selon un plan expérimental de type Plackett‐Burman à huit essais pourUcetUtr. Les facteurs et leurs niveaux de variation sont: (a) diamètre de la colonne (82 vs 200 mm), (b) particules (FCC vs sable), (d) hauteur statique du lit (300 vs 450 mm) et (g) distribution des particules (étroite vs large). Pour déterminer expérimentalement ces deux vitesses de transition, nous avons utilisé un capteur de pression différentiel et une sonde à capacitance. Les résultats expérimentaux et l'analyse statistique montrent que le diamètre de la colonne est le facteur le plus important (61% de variabilité pourUcet 51% pourUtr). Les propriétés du solide (ρp, dp) viennent en deuxième lieu (35% de variabilité pourUcet 47% pourUtr). L'effet de la hauteur statique est très faible et la distribution des particules n'a pratiquement pas d'effet sur les deux vitesses. Les résultats montrent aussi qu'il n'y a pas d'interactions entre ces paramètres. Enfin, nous avons proposé deux corrélations pour prédireUcetUtr

ISSN:0008-4034    

DOI:10.1002/cjce.5450730104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe maximum spoutable bed height of systems of fine glass spheres spouted with water is studied in a flat based, semi‐circular column of 80 mm diameter using glass spheres of diameters 0.300, 0.377, and 0.450 mm.A new correlation is proposed to predict the maximum spoutable bed height in water spouted fine particle systems. The same correlation is suggested for use with air spouted fine particles larger than 0.5 mm. It is concluded that in fine particle systems the jet penetration is significantly lower than that in coarse particle systems. The influence of the column diameter on the maximum spoutable bed height is also decreased significantly compared to coarse particle systems. Data reported in the literature for other water spouted fine particle systems agree with the correlation proposed in this wor

ISSN:0008-4034    

DOI:10.1002/cjce.5450730105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractLes coefficients de transfert de matière volumétriques de la phase liquide pour l'oxygène sont déterminés en colonne à bulles et en lit fluidisé. Le concept d'une variation axiale du coefficient de transfertklaexponentiellement décroissant conduit à une meilleure représentation des profils de concentration en oxygène dissous à l'intérieur de la colonne. Contrairement à la colonne à bulles, les variation axiales deklasont très importantes surtout dans la partie inférieure de la colonne en lit fluidisé où la présence de particules solides accélère le phénomène de coalescence particulièrement marqué p

ISSN:0008-4034    

DOI:10.1002/cjce.5450730106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractHeat transfer coefficients between the bed and an immersed horizontal tube in the grid‐region of a shallow gas‐solid fluidized bed were experimentally and theoretically studied. Experiments were carried out in two fluidized bed columns with inside diameters of 88 and 137 mm, respectively. The fluidized particles tested were sand, limestone and glass beads. Experimental parameters also included particle size, superficial gas velocity, tube diameter, tube location and distributor design. A mechanistic model considering the contributions of jet phase, emulsion phase and dead phase was derived for estimating the grid‐region heat transfer coefficients. Most of the model predictions were found to be within 25% of the experimentally observed

ISSN:0008-4034    

DOI:10.1002/cjce.5450730107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractFlow boiling in inclined tubes is encountered in solar collectors, but there is no literature on inclined flow boiling on which to base their design. Experimental studies have been carried out on heat transfer, pressure drop and flow maps for flow boiling of water in a circular tube. The angle of inclination was varied from 0° to 90°. The inclination was found to influence the transport processes in the bubbly and the intermittent flow regimes. The correlation of Chen (1966) has been extended to correlate the heat‐transfer data to account for the angle of inclination. The Baroczy (1965) and the Lockhart‐Martinelli (1949) correlations were adapted to correlate the frictional pressure gradient in the inclined flow boiling. The observed flow patterns were presented as flow

ISSN:0008-4034    

DOI:10.1002/cjce.5450730108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractOn a déterminé expérimentalement, par une méthode électrochimique, le coefficient moyen de transfert de matière entre des jets circulaires immergés verticaux de liquide, uniques ou multiples, et une nappe horizontale de mercure placée sous ces jets. Cette nappe est déformée par l'impact des jets et sa surface se trouve augmentée d'au maximum 30%. Des corrélations des résultats sont proposées. Dans le cas de jets uniques, le problème se trouve décrit d'une manière analogue à celui du transfert de matière dans une couche limite laminaire développée sur une plaque plane. Dans le cas de jets multiples, les corrélations sont empiriques, mais un support théorique a été considér

ISSN:0008-4034    

DOI:10.1002/cjce.5450730109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe intensification of mass transfer of acetic acid from kerosene into water across a plane interface by the application of an electric field normal to the interface is investigated.The application of an electric field affects mainly mass transport through the bulk of the organic phase rather than the interface. In the range (5–30) × 104V/m the mass transfer coefficient changes from 8 × 10−6to 2 × 10−5m/s. A model based on the movement of electric charges in the organic phase indicates that a Sherwood‐Grashof correlation for free convection only is also suitable for the electrically driven process if the Grashof number is modified to take into account the effect of the electric field on the movement of the electr

ISSN:0008-4034    

DOI:10.1002/cjce.5450730110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA series of Pb/Ca catalysts, promoted with Li, K and La, and prepared by different procedures, have been examined for the oxidative coupling of methane. The Li promoted Pb/Ca had the highest C2selectivity and yield of the catalysts studied, including the unpromoted Pb/Ca. For the Li/Pb/Ca catalyst, CO2added to the feed resulted in a decreased CH4conversion and an increased C2selectivity. Addition of H2O to the feed with the same catalyst, increased C2yield. These effects are discussed in terms of deactivation and regeneration of the active sites by CO2and H2O, respectively.

ISSN:0008-4034    

DOI:10.1002/cjce.5450730111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY