摘要:

AbstractThe effect of standing waves of controlled amplitude and frequency on the steady state rate of mass transfer through thin horizontal liquid layers is studied experimentally. The variables studied are the film thickness, the amplitude and frequency of the waves, and the spacing between the probes generating the waves. A bulk motion of complicated pattern known as drift is caused by the finite amplitude of the waves. The rate of mass transfer in the absence of imposed vibration is two to three times greater than that expected by molecular diffusion alone. Vibration increases the rate up to an order of magnitude or more, depending on the hydrodynamic conditions. The data at low frequencies are correlated by an expression of the form (i‐io)/idiff=KAf3/4h1/2L−

ISSN:0001-1541    

DOI:10.1002/aic.690140113

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThe phenomenological theory previously prsented for describing the rheological properties of non‐Newtonian materials was applied to two polymer solution systems. The basic shear diagram is needed over a wide range of shear rates and polymer concentrations, and such data are not readily available; however, what could be found supported the analysis. In order to confirm the theory further, ten solutions of polymethylmetacrylate in diethyphthalate with concentrations up to 55% were investigated at 40°C. The results indicated that the forward and reverse orders were 1 and 2 respectively and that the two parameters of the theory (a susceptibility to shear term and an equilibrium type of constant) were constant over the range of concentrations investigated. The flow data were reproduced to within a few percent for all solutions, although the errors were large for the very dilute concentration, where experimental difficulties precluded obtaining reliable data. The method allows correlation of polymer solution data over the range from lower to upper Newtonian viscosities and over a wide concentration ran

ISSN:0001-1541    

DOI:10.1002/aic.690140114

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThe selective, highly endothermic reaction of methylcyclohexane to toluene and hydrogen was studied experimentally over a commercial Pt/Al2O3catalyst, in an electrically heated tube serving as a packed‐bed reactor heat exchanger. The constant‐flux reactor, with measurement of temperatures within the bed at points intermediate along its length, proved well suited as an integral reactor for providing information on the reaction rate. A simple analytical model of the reactor was developed, and some of the data were used with the model to derive a rate expression.The model gives a good representation of radial variation of temperature in the packed bed. In the region of high Reynolds numbers investigated, radial transport of enthalpy is described in the model by a film resistance at the tube wall defined by heat transfer coefficient, and a diffusive transport through the packing, dominated by eddy diffus

ISSN:0001-1541    

DOI:10.1002/aic.690140115

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractLocally linearized equations for dynamic disturbances from a steady state have been solved analytically for an adiabatic chemical reactor with chemically inert packing and a homogeneous chemical reaction. The solutions, in the form of transfer functions, include the effects of heat capacity of the packing and heat transfer between the packing and the fluid, as well as the coupling effects of chemical reaction and the associated heat generation.Several limiting cases of the transfer functions are discussed and the transfer functions are simplified by an approximation of the temperature dependence of the reaction rate. Frequency responses and step responses of the reactor are calculated from the transfer functions.

ISSN:0001-1541    

DOI:10.1002/aic.690140116

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractA general method has been developed for controlling deterministic systems described by linear or linearized dynamics. The discrete problem has been treated in detail. Step‐by‐step optimal controls for a quadratic performance index have been derived. The method accommodates upper and lower limits on the components of the control vector.A small binary distillation unit was considered as a typical application of the method. The control vector was made up of feed rate, reflux ratio, and reboiler heat load. Control to a desired state and about a load upset was effected.Calculations are performed quite rapidly and only grow significantly with an increase in the dimension of the control vector. Extension to much larger distillation units with the same controls thus seems practi

ISSN:0001-1541    

DOI:10.1002/aic.690140117

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractA correlational procedure was developed to predict the vapor liquid equilibrium behavior of light hydrocarbons in heavier hydrocarbon solvents at low temperatures and elevated pressures. The method is applicable to paraffinic as well as aromatic solvents.The method employed the Benedict‐Webb‐Rubin equation of state to predict the vapor phase fugacities. Methane liquid fugacities in the various hydrocarbon solvents were based upon Henry's law which included terms to account for compositional and pressure effects. The liquid fugacities for ethane and propane were calculated using infinite dilution data to modify empirically the Scatchard‐Hildebrand equation. Excellent agreement between the correlated and low‐temperature data available on this class of systems was o

ISSN:0001-1541    

DOI:10.1002/aic.690140118

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractAn approximate theory for transient dispersion with combined free and forced convection in vertical tubes is developed and tested experimentally. It is found that the dispersion coefficient in such systems depends on a parameter α, which is defined by Equation (38). The analytical expression developed for the dispersion coefficient, Equation (33), is found to be a reasonably good approximation in the range −50<α<300.Experimental results are reported for a rather wide range of parameters for tubes with both 1 1/2 and 5 mm. diameters.It is found that the extent of dispersion is enhanced significantly when lighter fluid is on the bottom and displaces a heavier one. On the other hand, the dispersion coefficient is inhibited when the situation is reversed. It is found that these effects are not symmetrical with respect to the absolute magnitude of the parameter α as is illustrated in Figur

ISSN:0001-1541    

DOI:10.1002/aic.690140119

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThe intramembrane transport properties of carbohydrates were investigated in cellophane. The experiments performed were the measurement of net volume transfer under a concentration and pressure gradient and the solute transfer due to a concentration difference together with the physical properties of the membrane. The matrix of phenomenological coefficients characteristic to the transport was established after the phase boundary contributions were extricated from the experimental transport data. These thermodynamic coefficients were then interpreted through the Spiegler‐Kedem‐Katchalsky frictional model.The analysis of the frictional coefficients clearly indicated the importance of solute‐polymer interactions. The magnitude of solute‐solvent frictional coefficients in the membrane were compared with the corresponding interactions in free solutions. Their differences were explained in terms of the interaction of the solute with the macromolecular network and were quantitatively expressed by introducing two reduced frictional coefficients. The tortuosity factor was shown to be related to these interactions and not a simple geometric property of the membrane. The temperature dependence of the frictional coefficients was esta

ISSN:0001-1541    

DOI:10.1002/aic.690140120

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractEmpirical size‐dependent growth rate models are studied for their effect on the population density distributions from a continuous, mixed suspension, mixed product removal (CMSMPR) crystallizer. The growth rate models and/or their corresponding population density distributions are examined for continuity, convergence of moments, versatility, and their ability to fit experimental data.A new empirical size‐dependent growth rate model is proposed which has properties superior to those of previous models. Experimental steady state data are presented to illustrate the application of the model to actual CMSMPR crystallization syst

ISSN:0001-1541    

DOI:10.1002/aic.690140121

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThe theoretical equations for the flow of Newtonian fluids in a falling cylinder viscometer with eccentricity are developed. The error in fall velocity of the cylinder caused by eccentricity is determined and presented in tabular form. An approximate method to determine the error in fall velocity caused by eccentricity for non‐Newtonian fluids of the power law type is also presented. For the Newtonian case,n=1, the approximate method is shown to give excellent agreement with the exact metho

ISSN:0001-1541    

DOI:10.1002/aic.690140122

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY