ISSN:0001-1541    

DOI:10.1002/aic.690100302

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

ISSN:0001-1541    

DOI:10.1002/aic.690100304

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

摘要:

AbstractConstant pressure diffusion rates of hydrogen through Vycor porous glass were measured in nitrogen and neon systems. The experimental diffusivities are less than those predicted by the random pore model indicating that this model may not be satisfactory for a low porosity material such as Vycor. Interpreted in terms of an assembly of parallel pores the data suggest a tortuosity factor of approximately 2.4.Rate data for the ortho‐para hydrogen reaction were also measured at −196°C. and 1 atm. The catalyst 2% nickel/Vycor was found to have pore properties (area, mean pore size, pore volume) similar to that of plain Vycor. Predicted effectiveness factors using the experimental diffusion data were in good agreement with values determined experimentally. The latter were evaluated from rate measurements on both pellet and particles (58 μ mean diam

ISSN:0001-1541    

DOI:10.1002/aic.690100305

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

ISSN:0001-1541    

DOI:10.1002/aic.690100306

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

摘要:

AbstractFour different flow regimes may be identified during transport of dilute suspensions of solid particles through horizontal pipes by liquids in turbulent flow as the velocity is varied. The regimes may be characterized by the distribution of solids in the channel. In two of the regimes the bulk of the material is immediately adjacent to the bottom of the channel and is clumped up either into transverse waves (dunes or islands) with a reproducible periodicity or into longitudinal waves (long stria). The definition of the other two regimes is somewhat more arbitrary but may qualitatively be described as heterogeneous or homogeneous flow. Extensive studies of the conditions under which transverse and longitudinal waves occurred, when combined with results of previous studies, showed that all four of these flow regimes may be conveniently represented on a single diagram in which the terminal‐settling velocity divided by the friction velocity and the Reynolds number on particle diameter and friction velocity are the coordinates. Because the particle Reynolds number based on the terminal‐settling velocity can be uniquely defined as an additional parametre on such a diagram the particular flow behavior for any given combination of system and particle characteristics can be readily determi

ISSN:0001-1541    

DOI:10.1002/aic.690100307

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

摘要:

AbstractA computational method has been developed for obtaining the solution to a class of optimization problems by the combined use of the maximum principle and a maximum (or minimum) seeking technique on the analogue computer. Various maximum seeking techniques can be used for this method. However if the random search technique is used, this computational method has the advantage of being able to investigate a large number of operating (or controlling) variables.The calculation procedure is essentially a trial‐and‐error procedure which is alternately integration and maximum seeking operations. The variables over which the system is to be optimized are approximated by a finite number of straight line segmentsn. Thus the maximum (or minimum) of the Hamiltonian function which is obtained by the maximum principle need only be obtained atn+ 1 points along the optimization path (or trajectory).To illustrate the use of the method the optimum operating variable profiles (or gradients) in a tubular chemical reactor were computed.The present method, in addition to making it easier to investigate systems with a moderate number of state variables, can be used to solve problems with almost any kind of constraints and performance index encountered in ordinary optimum design problems. It offers some possibilities for on‐line optimizing control of a process. A special purpose analogue computer could be built for thi

ISSN:0001-1541    

DOI:10.1002/aic.690100308

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

摘要:

AbstractThe object of much experimentation is to build or discover a suitable model for a given system. Unfortunately very little work has been published on what constitutes good strategies in these situations. This paper is an attempt to formulate an approach to this important problem of iteratively improving models in the area of chemical engineering kinetics. In this technique a statistical analysis is applied to the estimated parameters of a tentatively entertained theroretical model in such a way as to pinpoint its inadequacies, if they exist, so that it is possible to proceed in a logical manner to an appropriate modification of this model. This modified model is then analyzed in a similar way, and further modifications are suggested. In general the cycle is repeated as often as is necessary to reach an adequate model. This sequential method is illustrated by finding an adequate reaction model for the total catalytic oxidation of methane.

ISSN:0001-1541    

DOI:10.1002/aic.690100309

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

摘要:

AbstractVelocity distributions, pressure gradients, and overall pressure drops are presented. A definite concavity was found in the velocity profile near the entrance for case I. In case II, which is more realistic physically, very definite effects are transmitted upstream, and the velocity distributions downstream show little concavity.

ISSN:0001-1541    

DOI:10.1002/aic.690100310

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

摘要:

AbstractSignificant changes in heat and momentum transfer rates can be caused by finite interfacial velocities and external field forces. This study considers the nonlinear problem of combined free and forced convection in vertical and horizontal two‐dimensional conduits with finite transverse velocity.Similarity transformations for the temperature function have been found which reduce the energy, momentum, continuity, and state equations for these configurations to nonlinear systems of two coupled ordianary differential euqations. These equations are solved by approximate methods to give Nusselt numbers and friction factors as well as velocity and temperature profiles.Stream to wall temperature differences increase with suction and decrease with injection. The effects of interfacial velocity on temperature profiles and heat transfer increase dramatically with Prandtl number. Because blowing and suction strongly affect temperature profiles they substantially modify natural convection effects in vertical flows. Suction creates steeper transverse temperature gradients and accentuates buoyancy effects in vertical flows. Conversely injection flattens temperature profiles and thus decreases the influence of buoyancy on the velocity fiel

ISSN:0001-1541    

DOI:10.1002/aic.690100311

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY

ISSN:0001-1541    

DOI:10.1002/aic.690100312

出版商:American Institute of Chemical Engineers    

年代:1964

数据来源: WILEY