摘要:

AbstractA model is described which accounts for partial segregation in continuous stirred‐tank reactors by considering packets circulating within a completely micromixed continuous regime. The packets have a nonideal residence time and concentration distribution. Mass transport occurs between these packets and the continuous phase of uniform composition in proportion to their concentration gradients. Laplace transformed tracer responses establish the diffusion and mixing parameters. Over 90% of the system is segregated in unstirred aqueous solutions. Addition of polymer increases segregation by over 40% at a 100 rev/min stirrer spee

ISSN:0001-1541    

DOI:10.1002/aic.690230303

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractAn efficient and simple numerical technique is presented for analyzing nonisothermal nip flow of viscous liquids. It has been applied on calendering to calculate the design parameters as well as the interaction effects between roller characteristics, operation conditions, and material properties. Viscous heating is shown to drastically change the mechanics near the nip exit if the rollers rotate at different speeds. Consequences for scaling‐up and model experiments are indicate

ISSN:0001-1541    

DOI:10.1002/aic.690230304

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractPressure drop correlations for flow of slurries in pipelines were developed for each of the following four flow regimes: flow with a stationary bed, saltation flow, heterogeneous flow, and homogeneous flow. A total number of 2 848 data points, comprised of 1 912 collected from the published literature together with 936 taken using our own test pipelines and relating to ranges of the pertinent variables extensive enough to span all four flow regimes were used as the basis of these correlations. Also, these data were used in developing an associated quantitative regime delineation scheme. The correlations provide an improved predictive capability over previously available procedures and are also broader in scope. The delineation procedure developed here permits straightforward classification of the data according to the flow regime prevailing, and it is moreover inclusive of all the data and is self‐consisten

ISSN:0001-1541    

DOI:10.1002/aic.690230305

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractTrajectories have been computed for two equal sized spherical particles in simple laminar shearing and in uniaxial extensional flows. Effects of interparticle attraction, electrostatic repulsion, and hydrodynamics were included.The results are pertinent to questions of colloidal stability under various conditions of flow. Particulate dispersions can react in several different ways as the intensity of shearing is increased from zero: the dispersion can remain stable; it can be redispersed, if it had been initially flocculated into a weak secondary minimum in the interparticle potential curve; it can be flocculated into a strong primary minimum in the potential curve; or, in extreme cases, it can be redispersed from the primary minimum. Results are presented which illustrate criteria for flocculation or stability to both laminar shearing and extensional flow. It is shown that hydrodynamic effects can significantly alter the criteria developed for stability of dispersions to Brownian coagulation.

ISSN:0001-1541    

DOI:10.1002/aic.690230306

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractAn isotropic, homogeneous packed‐bed reactor is modeled as an array of sinusoidal periodically constricted tubes (PCT). The effective asymptotic bed‐Sherwood number has been calculated for mass transfer at large Péclet number with a constant wall concentration and creeping flow hydrodynamics. The bed friction factor has also been calculated. The results for these macroscopic bed quantities depend upon two ratios of the microscopic PCT period length, average radius, and sinusoidal ampti

ISSN:0001-1541    

DOI:10.1002/aic.690230307

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractAlthough multicomponent, liquid phase adsorption is often encountered in industrial application, most of the studies concerning fixed‐bed sorption processes have been dealt primarily with systems containing one adsorbable species. The present work provides a numerical solution to the fixed‐bed, multicomponent adsorption problem, taking into account both separately or in combination the effect of liquid and/or solid phase mass transfer resistance and of variation of the assumed governing adsorption isotherm. Numerical solutions of several example problems are presented and compared with results based on equilibrium theory and a simplified method developed by Cooney and co‐workers previously (

ISSN:0001-1541    

DOI:10.1002/aic.690230308

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractNecessary and sufficient conditions for intrinsically stable equilibrium in a multiphase, multicomponent body are developed with interfacial effects taken into full account. There is a limiting criterion for intrinsic stability that must be satisfied within every phase, and there is another limiting criterion that must be satisfied on every phase interface. The limits of intrinsic stability for a multiphase, multicomponent body are defined by the failure either of the first criterion within one of the phases or of the second criterion on one of the phase interfaces.

ISSN:0001-1541    

DOI:10.1002/aic.690230309

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

ISSN:0001-1541    

DOI:10.1002/aic.690230310

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractAn analysis is performed to obtain an exact solution to the problem of thermal entry region heat transfer in a circular tube with an arbitrary circumferential wall heat flux for pseudoplastic fluids using the power law constitutive model. The solution is expanded in a power series form, with expansion coefficients and related constants obtained numerically. A simple result is presented for a cosine heat flux distribution around the periphery of the tube which illustrates the simultaneous influence of circumferential wall heat flux variation and non‐Newtonian fluid behavior on heat transfe

ISSN:0001-1541    

DOI:10.1002/aic.690230311

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY

摘要:

AbstractNew and extensive experimental data on the rate of growth of ice crystals in theaaxis direction in quiescent and slow flowing subcooled pure water show conclusively that thermal natural convection is an important heat transfer mechanism controlling the growth rate. At zero and low forced velocities, steady growth is observed only when the crystals grow horizontally or upward. Steady downward growth does not occur in quiescent water. This is consistent with the physical properties of water and the phenomenon of thermal natural convection.Growth rates at high water flow rates vary as the square root of the forced velocity and the 3/2 power of the subcooling and follow the theory of Fernandez and Barduhn (1967) with the ice‐water interfacial energy set at 52 mJ/m2(52 erg/cm2

ISSN:0001-1541    

DOI:10.1002/aic.690230312

出版商:American Institute of Chemical Engineers    

年代:1977

数据来源: WILEY