摘要:

AbstractThis paper reports a detailed study of the hydrodynamics involved in the operation of rotary disk contactors (RDC). New information is presented regarding the ‘critical rotor speed’ which divides the two hydrodynamic regimes of near constant and varying characteristic velocity of the dispersed droplet phase. Generalized correlations for prediction of characteristic velocity both above and below the critical rotor speed have been proposed under conditions of no solute transfer as well as solute transfer between the dispersed and continuous phases. Experimental data on mass transfer obtained in the two hydrodynamic regimes of RDC operation have also been correlated by the application of mass transport theory taking into account the factors affecting the interfacial area of contact, drop size, characteristic velocity and dispersed phase hol

ISSN:0008-4034    

DOI:10.1002/cjce.5450560201

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

年代:1978

数据来源: WILEY

摘要:

AbstractElliptic forms of the Navier‐Stokes equations in rigorously formulated toroidal coordinates are solved numerically for laminar, incompressible, isothermal flow in curved pipes of small curvature radius and 90° deflection angle. As a special case, the flow through curved annuli is also considered in which the presence of the inner curved wall causes the appearance of two (rather than one) pair of cross‐stream vortices. Recirculation in the main flow direction is observed at the outer curvature wall of a pipe with Rc/d = 1 and Re = 1800 over a deflection angle corresponding to 9° ≤ θ ≤ 21°. Flow reversal is attributed to the large and unfavorable longitudinal pressure gradient prevailing at the outer curvature wall over the first half of the pipe. Calculations show that the cross‐steam flow in a strongly curved pipe can be as large as 80% of the bulk average velocity at θ = 45° but is reduced in magnitude between θ = 45° and 90°.The numerical procedure used for the present calculations is a special case of a more general method which will solve flows in arbitrary curvilinear orthogonal coordinates provided the appropriate scale factors and extra source terms are included. A detailed derivation of the difference equations in curvilinear orthogonal coordinates is, therefo

ISSN:0008-4034    

DOI:10.1002/cjce.5450560202

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

年代:1978

数据来源: WILEY

摘要:

AbstractSteady countercurrent zero net flow of two immiscible fluids in an inclined circular tube has been studied under laminar flow conditions. Using appropriate dimensionalization, the interface position and viscosity ratio become the only two parameters that govern the flow. Velocity profiles and shear stresses were determined from numerical solutions of the equations of motion and are compared with the analytical solutions for flow between parallel plates. Such zero net flows are encountered at shutdown of long inclined slurry pipelines. The results of the present investigation are suitable for modelling these flows.

ISSN:0008-4034    

DOI:10.1002/cjce.5450560203

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe fully‐developed laminar flow between a circular tube and an eccentric moving cylindrical rod is predicted for eccentricities between zero and unity. For eccentricities less than unity, an earlier solution is extended to account for arbitrary rod (capsule) velocities; useful shear force expression in closed form are given. An entirely new solution for the fully eccentric case is presente

ISSN:0008-4034    

DOI:10.1002/cjce.5450560204

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

年代:1978

数据来源: WILEY

摘要:

AbstractA relatively simple and explicit mathematical expression has been developed for estimating the enhancement factors for mass transfer accompanied by a second‐order irreversible chemical reaction. The development is based on asymptotic characteristics, i.e., limiting solutions, for second‐order enhancement factors. The resulting mathematical relation and other approximate analytical formulations previously presented in the literature have been critically compared with a numerical solution for the diffusion‐reaction process based on film t

ISSN:0008-4034    

DOI:10.1002/cjce.5450560205

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

年代:1978

数据来源: WILEY

摘要:

AbstractEquations are developed for finite‐batch, irreversible adsorption where both pore diffusion and film resistance are significant. Quasi‐steady state behavior is assumed and comparisons are made for sheets, cylinders, and spheres. The equations for the three shapes are generalized to a single form. For equal volumes of adsorbent, when the external film controls, spheres attain equilibrium more quickly than cylinders, and cylinders more quickly than sheets. When internal diffusion controls and the ratio of the final to the initial solution concentration is high, this ordering of equilibrium times is preserved; however, if the ratio is very low, the ordering is rever

ISSN:0008-4034    

DOI:10.1002/cjce.5450560206

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

年代:1978

数据来源: WILEY

摘要:

AbstractCalculation methods for single‐ and multi‐stage permeation of a multi‐component mixture are presented. The use of the local permeate concentration in the formulation results in a relatively simple form of solution for the binary system in the cross‐flow pattern. A parametric analysis of the permeation cascade is given. For a given permeability of the more permeable component, there exists a membrane selectivity which gives rise to a minimum membrane area requirement in the cascade. It is shown that the compression power requirement is dependent only on the operating pressure ratios, irrespective of actual pressure levels in each stage. A study on the effect of interstage mixing loss shows that the ideal cascade (with no interstage mixing loss) is not necessarily always the thermodynamically most efficient one; some non‐ideal cascades may have higher efficiencies due to more effective permeation steps. Examples given relate to He/CH4and O2/N2se

ISSN:0008-4034    

DOI:10.1002/cjce.5450560207

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

年代:1978

数据来源: WILEY

摘要:

AbstractCalculation methods for determining pure gas permeabilities and gas separation performance of hollow fiber modules with significant permeate pressure drop inside the fiber are presented. A sequential optimization method for determining the near‐optimum permeate pressures in cascade operation is developed. It is shown that the performance of narrow hollow fiber modules can be significantly affected by the permeate pressure build‐up inside the narrow fiber. For a given module and given recovery there exists an optimum permeate outlet pressure which minimizes the membrane and permeate compression costs. Examples given relate to the recovery of helium from natural

ISSN:0008-4034    

DOI:10.1002/cjce.5450560208

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe decomposition of n‐butyl acetate on charcoal was studied at 365° and 385°C, and isobutyl acetate at 394° and 419.5°C. Isobutene and acetic acid were the principal products from the iso ester, and n‐butenes and acetic acid from the normal ester. Other primary and secondary reactions exceeded 20% in most experiments. The principal primary product from the normal ester was 1‐butene which isomerized subsequently to 2‐butenes; iso‐butene from the iso ester did not isomerize.For both esters the activity of the charcoal decreased rapidly, the conversion decreasing linearly with time. Linear correlations were used to estimate the conversion at zero time, and data at zero time were used to evaluate constants of a rate equation. Fouling was attributed to reactions of olefins which produced carbonac

ISSN:0008-4034    

DOI:10.1002/cjce.5450560209

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe kinetics of the vapor phase oxidation of p‐xylene over ferric molybdate catalyst were studied in an isothermal, differential, tubular flow reactor in the temperature range of 360 to 420° C. The major product obtained was p‐tolualdehyde with small amounts of maleic anhydride and p‐toluic acid. No terephthalic acid or CO2were observed.The reaction rate data collected fit the redox model given by Equation 1. The values of activation energies Ex, Eoand frequency factors Ax, Aoobtained are 72, 63 kJ/mol and 0.64, 2.89 m3/kg catalyst s respectively.The reaction mechanism was established by studying the oxidation of p‐tolualdehyde, toluic and terephthalic acids. It is concluded that the reaction follows a parallel‐consecut

ISSN:0008-4034    

DOI:10.1002/cjce.5450560210

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

年代:1978

数据来源: WILEY