摘要:

AbstractModels consisting of interconnected regions (dead‐water, backmix, plug flow, etc.) with various modes of flow through and around these regions (bypass, recycle, cross flow) are used to represent real vessels in which flow deviates greatly from plug flow. This paper deals with some of the problems of choosing and fitting such models, called mixed models, to represent flow in real vessels.The stimulus‐response technique is a useful tool for this purpose, and matching response curves for model and real vessel then serves as the selection method.Some of the simpler mixed models and their corresponding characteristic response curves are presen

ISSN:0008-4034    

DOI:10.1002/cjce.5450400402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

ISSN:0008-4034    

DOI:10.1002/cjce.5450400403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractContinuous phase mass transfer coefficients have been measured for carbon dioxide bubbles rising in water. A procedure was developed for systematically studying the effect of the three variables: bubble volume, formation frequency, and seal height.The mass transfer coefficient was independent of bubble volume, increased 35% with a ten‐fold increase in frequency and varied only 8% over a 30 cm. range in seal height. The data, extrapolated to zero frequency, agreed well with the single bubble study of Hammerton and Garner. The Higbie equation predicted results very close to those obtained here but was not too successful in explaining the effect of bubble size or frequency.The average mass transfer coefficient is about four times that for a solid particle as reported by Akselrud; this enhancement is attributed to internal circulation. Surface absorption rates were determined as a function of bubble frequency. New data has also been presented on the factors which control frequency, velocity of rise, and bubble shape. A partial correlation was developed relating bubble frequency to chamber volum

ISSN:0008-4034    

DOI:10.1002/cjce.5450400404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractVelocity profiles and volumetric rates for the axial, laminar flow of a Newtonian fluid in a circular pipe containing a fixed eccentric core were evaluated numerically using a digital computer. The velocity profiles agree exceptionally well with those evaluated from an analytical expression derived by Heyda(2). The effect of displacing the inner surface from a concentric position is to increase the volumetric flow rate for a given pressure gradient, the maximum increase for a diameter ratio of 0.9 being 240% and for a diameter ratio of 0.1, 60%.The volumetric flow rates are presented graphically in terms of dimensionless ratios which enable the flow rate to be evaluated for any fluid, diameter ratio, relative displacement and pressure gradient.

ISSN:0008-4034    

DOI:10.1002/cjce.5450400405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractIn a large class of chemical systems, it may be desired to determine the inlet conditions that enables the process to be run in order to meet certain constraints, such as a specified product yield or required temperature. This paper uses Lagrangian Multipliers for solving, numerically, a particular aspect of this problem namely that of determining inlet conditions so as to maximize (or minimize) a characteristic of the reaction and simultaneously meet required constraints.

ISSN:0008-4034    

DOI:10.1002/cjce.5450400406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractThe measurement of particle temperature in gas‐solids suspensions by conventional pyrometric methods is complicated by a lack of knowledge of the particle emissivity and the absorption strength of the cloud. Further difficulties may be caused by background re‐radiation, variations in geometrical factors and ‐ if the particles are undergoing chemical reaction ‐ rapid changes in the particle temperature. These difficulties can be eliminated if the radiant energies emitted by the particles at two different wavelengths (close in value) are measured simultaneously.A pyrometer based on this principle was designed and constructed for measuring temperatures both in the infra‐red (500–900 C.) and the visible (800–1200°C.) ranges. The radiation from the particles was passed through suitable pairs of monochromatic filters inserted in diametrical opposition into a metal disk rotating at speeds up to 8,000 r.p.m. The two alternating beams were focused on the cathode of a photoelectric cell, and the resulting voltages measured by means of a cathode‐ray oscilloscope. The instrument was used successfully in an investigation of the rate of reduction of small iron oxide particles in the presence of hydrogen at temperatures ranging fr

ISSN:0008-4034    

DOI:10.1002/cjce.5450400407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractRadial thermal conductivities in packed beds have been extensively studied and correlated, but there is little published work on axial conductivities. The data on axial conductivities that is available is limited to low flow rates because of measurement difficulties at high flow rates. In this paper, a method is presented for estimating the values of axial thermal conductivities at high flow rates from the existing data on radial thermal conductivities. The necessity for considering packed bed axial conduction in design work can be determined from these results.

ISSN:0008-4034    

DOI:10.1002/cjce.5450400408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractRates of mass transfer from water drops into cyclohexanol and from drops of cyclohexanol, isobutanol, and o‐toluidine into water were measured. These experimental data were augmented by published results, to cover, at drop Reynolds numbers less than 10, a Peelet number range of 0.01 to 5,000,000 for non‐circulating spheres and 700 to 24,000,000 for circulating spheres. Transfer rates, expressed as Sherwood numbers, were in substantial agreement with those predicted from a theoretical model. The contribution of natural convection, inherent in the measurements, but omitted in the model, was approximately accounted for. Data for circulating spheres verified the hypothesis that internal motion affects the external transfer rate. This effect depends on the ratio of continuous to disperse phase viscosity of the system; a four to six‐fold enhancement of mass transfer due to internal circulation was found for water drops falling in cyclohe

ISSN:0008-4034    

DOI:10.1002/cjce.5450400409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractApplication of dimensional analysis and experiment to the operation of a hydrocyclone yielded an equation of the form:This equation shows that the volume throughput Q is a function of the pressure differential P, the density δ and the viscosity μ of the medium. The constant K1and the coefficients of the pressure differential, density and viscosity were shown by statistical analysis to be relatively simple functions of the dimensions of the body and orifices of small glass hydrocyclones used with liquid medi

ISSN:0008-4034    

DOI:10.1002/cjce.5450400410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY

摘要:

AbstractThe nature of the diffusive mechanisms in the pore spaces of catalytic solids is briefly reviewed, and the effective diffusion coefficient is discussed. Binary diffusion equations, including a general expression covering all modes of diffusion, are given. Using the general diffusion equation together with first order reaction, a solution for isothermal conditions and slab type geometry is found, applicable to all modes of diffusion, with or without volume change on reaction. The extension of this solution to other pellet shapes and to second order reactions is discussed.The measurement of diffusion rates in porous solids is considered, and the interpretation of such measurements in terms of effective diffusion coefficients is clarified by means of the general diffusion equation. Methods of determining effective diffusion coefficients other than by direct diffusion measurements are discussed, and, in particular, a forced flow technique is reviewed.

ISSN:0008-4034    

DOI:10.1002/cjce.5450400411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1962

数据来源: WILEY