摘要:

AbstractHolographic techniques employing a pulse ruby laser were used to measure the size and velocity of drops for air‐water two‐phase critical flow at quality levels above 0.95. The use of a large numerical aperture in the holographic recording system permitted diffraction limited resolution of the droplets. The measured slip ratio a long withthe observation that a very significant portion of the liquid phase was concentrated near the boundary layer at the exit plane indicates that a separated flow model describing two‐phase critical flow would represent the actual conditions to a better degree than the other m

ISSN:0001-1541    

DOI:10.1002/aic.690200202

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractThe effect of changing platinum crystallite size from 2.7 to 15.5 nm on the specific catalytic activity in NO reduction by NH3, with and without added O2, was studied over alumina supported platinum catalysts between 423 and 473°K. In the NO‐NH3system both specific catalytic activity and selectivity to N2are independent of crystallite size. In the NO‐O2‐NH3system the specific catalytic activity of the 15.5 nm crystallites is about six times that of the 2.7 nm crystallites. The NO reduction rate shows dependence on NO to the first power and on NH3to the one‐ha

ISSN:0001-1541    

DOI:10.1002/aic.690200203

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractMost models for fixed bed adsorbers have used either the homogeneoussolid or pore diffusion model for the pellets. When the adsorption isotherm is linear, the two models can lead to identical breakthrough curves. The conditions for this equivalence are presented here. It is shown that one of the bulk flow factors that was included in the formulation of one pore diffusion model will be significant only for feedstreams containing a relatively high concentration of adsorbate. The prosity factor of the pore model is shown to be very important, especially as the porosity decreases. The importance of the two diffusional models with respect to the predicted breakthrough curves is demonstrated. For comparable beds, it is shown that the breakthrough curve based on the homogeneous model is delayed with respect to that based on the pore model at early times, regardless of the shape of the isotherm. Finally, the various possible solutions for an irreverisble isotherm are reviewed for each of the models, and a solution is presented for the general case of a pore model with an outside film resistance.

ISSN:0001-1541    

DOI:10.1002/aic.690200204

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractA calculation procedure for multicomponent distillation has been developed that is directly applicable to design problems. It is based on successive approximation methods with adjustment of the number of equilibrium stages in each column section between iterations to meet given reflux flow and feed stage composition conditions while maintaining specified key component recoveries. This procedure has been applied to a number of representative distillation design problems. It converges readily to proper column designs from initial estimates based on a noniterative stage‐to‐stage calculation. Moreover, the procedure is markedly superior in computational efficiency to solution of design problems by repeated application of operating calculations to assumed column configurati

ISSN:0001-1541    

DOI:10.1002/aic.690200205

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractUsing the Karman‐Pohlhausen integral method, an analysis has been made for turbulent flow on a rotating hemispherical electrode mounted on an inert support rod of equal radius. The resulting friction coefficient is then substituted into the Chilton‐Colburn relation to give a rate equation for mass transfer at high Schmidt numbers. Experiments with a diffusion‐controlled electrolytic system over a range ofScfrom 910 to 6,300 confirm the validity of the theory forRe>40,000. A comparison with the results of previous heat and mass transfer measurements reveals that the turbulent flow on the present geometry is different from that on a rotating sphere and on a hemispherical electrode mounted on a support rod of larger r

ISSN:0001-1541    

DOI:10.1002/aic.690200206

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractA new objective function for estimating parameters in differential equations, based upon a weighted least squares criterion for the residuals of these equations, is presented. The use of Lobatto quadrature in combination with the collocation technique reduces the original problem to one of minimizing a simple algebraic expression with respect to a series of unknowns. The method can be applied to different types of differential equations as shwon by a series of examples and leads to very good estimates. It becomes particularly useful for systems which are linear in the parameters and for which all states are observable since in this case the usual convergence problem is avoided. The gain in computation time when compared with classical methods is significant.

ISSN:0001-1541    

DOI:10.1002/aic.690200207

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractSteady state multiplicity in exothermic adiabatic reaction systems has previously been demonstrated by a number of authors. Specifically, the work of Root and Schmitz proved the existence of multiple steady states in a loop reactor, but difficulty was encountered in controlling such a reaction system at the intermediate steady states.Since a close analogy can be demonstrated between loop reactors and controlled cycled reactors (CCTR), it appeared reasonable to attempt to achieve steady state multiplicity in a CCTR. When the chemical reaction of Root and Schmitz was carried out in a CCTR, it proved relatively easy to obtain experimental values of intermediate steady statesf and to control the reactor at these conditions by means of a simple on‐off temperature controller.This work suggests that chemical systems displaying steady state multiplicity can be experimentally investigated in a CCTR and that cyclic operation may be the best way for controlling such reactions system

ISSN:0001-1541    

DOI:10.1002/aic.690200208

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractA new correlation of second virial coefficients of both polar and nonpolar systems is presented. It uses the Pitzer‐Curl correlation for nonpolar compounds, but in a modified form. The second virial coefficient of nonhydrogen bonding compounds (ketones, acetaldehyde, acetonitrile, ethers) and weakly hydrogen bonding compounds (phenol) is fitted satisfactorily with only one additional parameter per compound, which is shown to be a strong function of the reduced dipole moment. Two parameters are needed for hydrogen bonding compounds (alcohols, water), but for alcohols, one parameter has been kept constant and the other expressed as a function of the reduced dipole moment. The extension of the correlation to mixtures is satisfactory, direct, and involves only one coefficient per binar

ISSN:0001-1541    

DOI:10.1002/aic.690200209

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractPolydisperse submicronic lead chloride aerosols were generated from melt phase under dry and humid conditions. The particle size and concentration increased with increasing generation temperature. The aerosol particles generated in a dry atmosphere were pherical while the aerosol particles generated in humid atmosphere showed development of crystallinity at the surface.Coagulation rates of the aerosol generated in a dry atmosphere were measured at room temperature under different humidities. The coagulation rates were in goodagreement with Smoluchowski's theory, modified to include the effect of polydisperisity and were unaffected by humidity. The interaction of lead chloride particles with the water vapor was characterized by a process of adsorption a the interfce. The coagulated aerosol exhibited a chain structure for humidities lower than 70% and, at higher humidities, compact agglomeration was observed.

ISSN:0001-1541    

DOI:10.1002/aic.690200210

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY

摘要:

AbstractTransient sorption rates of allene and methylacetylene in synthetic faujasite (Linde 13X) powder and self‐bonded pellets are studied in a constant‐volume, constant‐pressure system at three temperatures. The intracrystalline diffusion coefficients are found to be in the order of 10−11cm2/s and the activation energy for diffusion is 4.0 kcal/g‐mole.A simple bipore distribution model for transient diffusion in macropores and micropores is presented. It agrees well with the experimental data and quantitatively predicts the macropore diffusion coefficients. The flow in the macropores is found to be in the Knudsen fl

ISSN:0001-1541    

DOI:10.1002/aic.690200211

出版商:American Institute of Chemical Engineers    

年代:1974

数据来源: WILEY