摘要:

AbstractA survey is given of co‐rotational rheological equations suitable for describing the flow of viscoelastic liquids such as polymer solutions and melts. Comparisons are given with experimental data and molecular theories. An introduction to kinematical descriptions in co‐rotating reference frames is inclu

ISSN:0001-1541    

DOI:10.1002/aic.690200602

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractAn overview of a nondestructive semimicro mechanical technique–pioneered, developed, and exploited by the author–which is used for characterizing phase transitions and transformations in polymeric materials is presented. Particular attention is given to literature published since January, 1972, which pertains to advances in automation, data acquisition and processing, and application to polymeric systems. The instrument has been consolidated as a powerful and convenient mechanical spectrometer in this short per

ISSN:0001-1541    

DOI:10.1002/aic.690200603

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractOne challenging problem in liquid‐gas, interfacial phenomena is the prediction of the size and location of a flowing meniscus because it involves surfaces which are highly curved. The paper presents one aspect of this problem. A numerical method is presented for predicting the dynamic meniscus profiles–specifically these distorted considerably by flow. The geometry considered to provide those free (liquid‐gas) surfaces is coating of a moving sheet by upward withdrawal from a finite bath. The predicted profiles agree with data taken with a glycerine‐water solution and with viscous oils.The method predicts the three parameters (coating thickness and two others) which are the minimum number of parameters necessary to describe the dynamic‐meniscus profiles for this geometry. The numerical method is iterative, it simultaneously predicts the flow field in the bath, and it is based on the two‐dimensional Navier‐Stokes equations and appropriate boundary conditions. The interfacial boundary condition used for iteration is the normal stress condition which is composed of pressure, surface tension, and

ISSN:0001-1541    

DOI:10.1002/aic.690200604

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractSimplified expressions to calculate the extent of reaction in a fluid bed show good agreement with the experimental data of Lewis et al. (1959) and Swaay and Zuiderweg (1972). The contribution of the dilute phase seems more important than that of the jetting zone or reaction factor (Hatta number) in usual fluid bed operations. The effect of the dilute phase is discussed. It is profitable to use the dilute phase for the consecutive isothermal and endothermic reaction, but unprofitable for the exothermic reaction. These characteristics depend upon the nature of reactions and careful considerations as to the choice of the gas velocity, particle characteristics, and reactor design will be necessary.

ISSN:0001-1541    

DOI:10.1002/aic.690200605

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractLow‐pressure solubilities of methane, ethane, propane,n‐butane,iso‐butane, and hydrogen have been measured inn‐hexadecane,n‐eicosane, squalane, bicyclohexyl, octamethylcyclotetrasiloxane, diphenylmethane, and 1‐methylnaphthalene over the temperature range 25° to 200°C. The accuracy of these measurements is better than 1%. The data for the hydrocarbon gases have been correlated with a generalized configurational entropy and a van Laar‐type interaction parameter. The entropic component of that parameter is related to the free volume of the solvent as suggested by Flory's equation‐of‐state theory of fluid mixtures. The accuracy of the correl

ISSN:0001-1541    

DOI:10.1002/aic.690200606

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractA lyotropic protein liquid crystal was studied experimentally to evaluate its potential as a selective liquid membrane. Concentrated solutions of fibrinogen had nematic like properties under shear and exhibited graded selectivities toward solutes of widely differing sizes when subjected to a two‐dimensional velocity field. The magnitude of the selectivity differences was found to depend on the shear orientated direction of the liquid crystal layer. The selectivity seems to be both a solubility phenomena and a relative diffusion phenomena. These anisotropic layers may have potential as controlled variable selectivity membrane

ISSN:0001-1541    

DOI:10.1002/aic.690200607

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractSurface diffusivities of benzaldehyde in liquid‐filled pores of Amberlite particles (polystyrene) were measured at 25°C using water as a solvent. For particles of different surface areas but chemically similar pore surfaces, the intrinsic surface diffusivityDs' was about the same, but the relative importance of surface to pore‐volume diffusion increased with surface area. For a single type of particle, the adsorption capacity was decreased about twenty‐fold by adding up to 19 mole % methanol to the solvent. This was accompanied by an increase inDs' from 1.2 × 10−8to 1.2 × 10−7cm2/s. These results were interpreted in terms of a two‐step theory for surface migration: (1) formation of a vacant site on the adsorbent surface followed by (2) movement of the adsorbate molecule into the site by breaking the surface‐adsorbate bond. The theory predicts that surface transport will be large when the surface area is high and that theDs' will be large when the heat of adsorption is low, and when the bond between solvent molecules and the surface is weak.In our studies the surface contribution to intraparticle transport was as much as 20 times the contribution due to pore‐volume diffusion. This ratio increases as the concentration of adsorbate in th

ISSN:0001-1541    

DOI:10.1002/aic.690200608

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractThe performance of a continuous, vertical, dense‐bed column crystallizer is evaluated by comparing experimental and predicted column temperature profiles and by examining product composition at various operating conditions. The separation obtained in an eutectic system is modeled by a component conservation equation coupled with a nonadiabatic energy balance equation. The critical parameter in the analysis is the axial dispersion coefficient and the measured values of this coefficient were similar in magnitude to those reported for ice washing columns. The dense‐bed column apparently achieves nearly ideal plug f

ISSN:0001-1541    

DOI:10.1002/aic.690200609

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractA counterexample is given to the strong maximum principle for boundary control of a class of distributed parameter systems. The particular system deals with chemical reactors suffering catalyst decay and is in the class whose members are described by sets of first‐order partial differential equations of the hyperbolic type. It is shown that an optimal control exists and that over any finite time interval in which the control is unconstrained the exit conversion from the reactor remains constant. It is further shown that for certain values of the parameters the optimal control policy violates the necessary conditions of the strong maximum principle for boundary control of distributed parameter system

ISSN:0001-1541    

DOI:10.1002/aic.690200610

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the problem of designing satisfactory loworder (incomplete state feedback) controllers starting with a high‐order, state‐space model. Two design approaches are considered: the control law reduction technique, recently developed by the authors (Wilson et al., 1973), and the well‐known model reduction approach. These two design techniques are used to develop a variety of low‐order controllers for a double‐effect evaporator starting with a 10th‐order model. Experimental and simulated response data from the computer‐controlled evaporator demonstrate the superiority of the control law reduction approach in this application. It is also shown that several of the previously published modal approaches to model reduction are basically equivalent since they yield identical reduced

ISSN:0001-1541    

DOI:10.1002/aic.690200611

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY