摘要:

An analysis of reaction rate enhancements by forced concentration oscillations of reactants for an adsorption/desorption type model with Eley-Rideal surface kinetics, is presented. Under cycling conditions in which the cycle time approaches zero, there is considerable rate enhancement relative to optimal steady state for nonlinear kinetics but no improvement for linear kinetics. The presence of inerts or products from irreversible reactions deteriorates the rate enhancement. For cycle times approaching infinity, there is no rate enhancement for either linear or nonlinear kinetics.

ISSN:0098-6445    

DOI:10.1080/00986448608911786

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Natural convection mass transfer at horizontal cylinders was studied using an electrochemical technique involving the deposition of copper from acidified copper sulphate solution. Cylinder diameter and copper sulphate concentrations were varied to provide a range ofSc. Grfrom 1.55 × 1010to 2 × 1012. Under these conditions, the data were correlated by the equation:

ISSN:0098-6445    

DOI:10.1080/00986448608911787

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A simulation code is developed to generate three-dimensional, square columns with rigid walls and packed with equal or unequal spheres. Geometrical characteristics of these columns such as porosity variations, coordination number, surface area per unit volume, etc. which are of interest for chemical engineering applications are studied. Emphasized is the wall effect, that is, the relatively high porosity near a wall, on the geometrical characteristics.

ISSN:0098-6445    

DOI:10.1080/00986448608911788

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper deals with the application of a general predictive controller to a pulsed liquid-liquid extraction column. The control purpose is to maintain the column in its optimal behaviour zone in spite or flowrates and physical properties of solvent and solute fluctuations. The complex dynamics of the column is modeled by a low order linear discrete model with time varying parameters which are recursively identified. Based on these estimates, the control policy is adapted on line.

ISSN:0098-6445    

DOI:10.1080/00986448608910016

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0098-6445    

DOI:10.1080/00986448608910017

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A semi-theoretical study of porosity of particulate beds composed of mixtures of various size spherical particles has been performed. A model for mixtures of only two particle sizes is developed and is used to identify several dimensionless parameters which are correlated by comparing predictions with the data. The model is then extended to evaluate porosity of mixtures of a large number of particle sizes and distributions. The predictions from the model are found to compare quite well with the data taken in this work and the existing data in the literature when unavailability of a certain fraction of pores formed of largest size particles in the mixture is accounted for.

ISSN:0098-6445    

DOI:10.1080/00986448608910018

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Gelled polymers are being used increasingly to modify the movement of injected fluids in secondary and enhaced oil recovery processes. A common gelation process involves the reduction of Cr(VI) to Cr(III) in the presence of polyacrylamide. The Cr(III) reacts or interacts with the polymer to form a gel network. Although correlations of gelation time with principal process variables have been obtained, viscometric data have not been reported during or after gelation. These data are needed for fluid flow calculations in surface equipment and estimation of flow behaviour in reservoir rocks.

ISSN:0098-6445    

DOI:10.1080/00986448608910019

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Horizontal pipeline and tubular loop aerators are of interest for fermentation and waste water treatment and are ideally suited for continuous processing. A major drawback is that these pipeline contactors invariably operate in the “elongated bubble and plug” regime in which the mass transfer rate is low. This article evaluates the performance of a horizontal pipeline aerator fitted with nozzles equispaced along its length to enhance mass transfer rates by promoting turbulence and augmenting effective interfacial area. Such devices can also be advantageously used in long pipe lines as in the case of treating waste while it is being transported. Pressure drop and overall liquid-side mass transfer coefficient data are reported as functions of liquid (water) and gas flow rates and nozzle size and spacing. It is shown that for all the conditions studied,kLa= 0.026(ΔP/L)1.036and that the pressure gradient is given by a simple correlation, provided an empirical parameter which characterises a nozzle is known. Preliminary investigations on the effect of surfactant ad the presence of suspended solids (size 75 μm) on mass transfer coefficient are also reported. Very high values of power dissipation can be achieved in such aerators without mechanically moving parts and high values of mass transfer coefficient can be realized.

ISSN:0098-6445    

DOI:10.1080/00986448608910020

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In order to investigate hygroscopic moisture transfer in fibrous material, experiments were conducted to measure the mass flux and moisture distribution through a sample of glass fiberboard (138kg/m3). The samples ranging in thickness from 0.0388 to 0.053 m were exposed isothermally to relative humidity gradients ranging from 35 to 100%. The equilibrium moisture content was used as the driving force for transfer. The mass conductivity was calculated from the flux and distribution data and found to vary from 0.199 to 0.348 g/cm-hr (5.53 × 10−6to 9.67 × 10−6kg/m-s) increasing slightly with increasing relative humidity difference. The data was also used to calculate the mass diffusivity and permeability of the fiberglass. The results from this study were combined with data from earlier work on thermal mass transfer to determine the thermal mass conductivity of fiberboard and to provide an overall description of nonisothermal mass transfer. A better understanding of overall hygroscopic moisture transfer is important in the determination of drying and condensation rates.

ISSN:0098-6445    

DOI:10.1080/00986448608910021

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The design of multistage fluidized beds for heat exchange necessitates the solution of the mass and energy balance equations combined with the equilibrium relations for each stage. This paper presents a novel way of applying well known methodology to a different technology, one where it has not been widely applied.

ISSN:0098-6445    

DOI:10.1080/00986448608910022

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor