ISSN:0001-1541    

DOI:10.1002/aic.690310702

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractLocal instantaneous solid‐liquid mass transfer coefficients were measured in two‐phase gas‐liquid downflow through packed columns for 3 × 3 mm and 6 × 6 mm cylinders. An electrochemical technique was used. Liquid flow rates from 3.0 to 26.6 kg/m2·s and gas flow rates from 0.07 to 1.16 kg/m2·s covered the gas‐continuous, ripple, and pulse flow regimes. Time‐averaged mass transfer coefficients in trickle flow and in pulse flow for the pulse proper and the base (outside the pulse) were found to increase with increasing gas and liquid rates. Correlations are presented in terms of liquid phase Reynolds numbers and in terms of Kolmogoroff numbers. The mass transfer coefficients in the pulse were found to correspond closely to the coefficients that would be attained in the dispersed bubbl

ISSN:0001-1541    

DOI:10.1002/aic.690310703

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractThe surface dynamics of pendant aqueous droplets forming at a submerged nozzle in an immiscible organic solvent have been studied using a novel laser‐activated photochromic tracer technique. This enabled a small element of surface to be labeled so that its subsequent history could be recorded photographically.Results for aqueous droplets forming in toluene in the absence of any mass transfer indicated only a slow interfacial circulation from the front to the rear, and there was no indication of any surface renewal as a result of hydrodynamic flow even at nozzle Reynolds numbers as high as 300. By contrast, the introduction of any one of a number of organic solutes into the toluene phase led to sporadic Marangoni‐type interfacial disturbances, which in turn resulted in rapid replacement of elements of the droplet surface. It is proposed that renewal of the droplet surface is dependent on solute diffusion in the present instance and that the processes of surface renewal and mass transfer are likely to be interact

ISSN:0001-1541    

DOI:10.1002/aic.690310704

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractA perturbation chromatography technique using radiotracer gases has been developed to determine the adsorption equilibrium constants and diffusivities in molecular sieves. The ethane and ethylene 13X molecular sieve systems were studied in regions of high concentration. The data obtained by this technique are shown to be in agreement with equilibrium data obtained by static methods and with kinetic data obtained by adsorption uptake and chromatographic methods, but not with kinetic data obtained using NMR techniques. The tracer‐pulse chromatographic technique is much more efficient for obtaining gas adsorption equilibria and intraparticle diffusivities and is considerably easier to adapt to wide pressure and temperature ranges than the conventional method

ISSN:0001-1541    

DOI:10.1002/aic.690310705

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractA generalized methodology for estimating minimum fluidization velocity at elevated pressure and temperature was developed on the basis of a general correlation for pressure drop through fixed beds of spherical particles proposed by Barnea and Mizrahi (1973) and extended by Barnea and Mednick (1975). Comparison with experimental results shows good agreement.

ISSN:0001-1541    

DOI:10.1002/aic.690310706

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractThe filtration efficiency of a granular bed filter was investigated in the domain where inertial effects are dominant. A filtration model predicting single sphere and total bed efficiencies based on trajectory calculations of dust particles in the voids of the granular bed was developed. The model uses the flow field in a bed of spheres arranged in a body‐centered cubic array for which the filtration efficiency was found to be a function of a modified Stokes number defined bySt′ =St×Fwhere the functionFdepends only on the Reynolds number. The value of the functionFcan be found experimentally or predicted from the Ergun correlation to beF= 1 + 0.0157Re. The filtration efficiency calculated using the model agrees well with experimental results obtained in beds of dense cubic packing of spheres especially at relatively low Reynolds numbers (Re0.01). The prediction of the theoretical model also agrees well with experimental data for randomly packed beds at low porosities and low Reynolds

ISSN:0001-1541    

DOI:10.1002/aic.690310707

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractThe mixing of gases and particles in confined, coaxial jets with angular secondary steam injection into suddenly expanded mixing chambers was studied. The effects of secondary stream injection angle, mixing chamber diameter and length, primary jet solids loadings, particle size, and secondary stream velocity on particle and gas mixing rates were determined. Gas mixing was much faster than particle mixing. Angular secondary injection significantly increased the initial gas and particle mixing rates but had little effect on the overall length of duct needed for complete mixing. The effects on initial gas mixing rate of combined angular secondary injection and increased secondary velocity were additive.

ISSN:0001-1541    

DOI:10.1002/aic.690310708

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractThe concept of the trailing vortex introduced by van't Riet and Smith (1975) is used for evaluation of the mean velocity and intensity of periodic velocity fluctuations in the turbine impeller discharge flow. From the analysis of forces acting on the trailing vortex, it follows that geometric similarity in the impeller discharge flow can be expected for the Reynolds number rangeReε 〈1.5 × 104; 9.0 × 104〉 and for the radial distance up to one‐tenth of the impeller diameter. The calculated profiles of mean velocity and intensity of periodic velocity fluctuations agree with published data and permit the declaration of boundary conditions for the impeller discharge flow for numerical modeling of turbulent fluid flow in turbine impeller agitat

ISSN:0001-1541    

DOI:10.1002/aic.690310709

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractA theory for the identification of criteria within which a continuous isothermal mixed‐suspension, mixed‐product removal (MSMPR) crystallizer can exhibit concentration multiplicity (i.e., multiple steady states) is developed. Power law growth and power law magma‐dependent nucleation kinetic models are used to describe the crystallization kinetics. Applications to specific cases together with figures delineating regions of multiplicity are presented. The stability of these steady states is analyzed by using small perturbations around the steady state. Growth ratedispersion is shown to be unimportant in establishing this concentration multipl

ISSN:0001-1541    

DOI:10.1002/aic.690310710

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY

摘要:

AbstractThis paper demonstrates the application of the theory of temperature multiplicity to the continuous mixed‐suspension, mixed‐product removal (MSMPR) cooling crystallizer as described by the coupled solute and energy balances along with the associated population balance transformed into moment equations. Exact uniqueness and multiplicity criteria are developed. Applications to specific cases together with diagrams depicting the effects of the important variables on the regions of multiplicity and uniqueness are presen

ISSN:0001-1541    

DOI:10.1002/aic.690310711

出版商:American Institute of Chemical Engineers    

年代:1985

数据来源: WILEY