ISSN:0001-1541    

DOI:10.1002/aic.690140502

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractVarious modifications of the Prandtl mixing‐length model for turbulent momentum transport in pipes and between parallel plane walls are discussed. The most complete modification, due to Gill and Scher, is improved by replacing one of their two empirical constants by a theoretically calculable parameter. The new theory is compared with experimental data from the literature and found to reproduce frictional resistance data accurately for all values of the Reynolds number. It is somewhat in error for velocity profiles at high Reynolds numbers, but accurately reproduces velocity profile data in the transition region. The new theory represents the first accurate semi‐theoretical calculation of frictional resistance coefficients for all regimes of flow (laminar, transitional, and turbulent) for both pipes and parallel plane ducts, and of velocity profiles in the transitional flow regime in either geome

ISSN:0001-1541    

DOI:10.1002/aic.690140503

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractThe fundamental problem in this work was to determine if methods of predicting mass transport rates in porous catalysts, developed from theory in the absence of chemical reaction, are valid in the presence of reaction. By using the ortho‐para shift of hydrogen over a ferric oxide gel catalyst as the reacting system, the effective diffusivity within the catalyst was determined from kinetic data on five different particle sizes of the catalyst. This effective diffusivity was then compared with that predicted by three different procedures recently published. These procedures predicted diffusivities approximately 40% below the experimentally obtained diffusivity. Although the differences between the experimental and predicted effective diffusivities can be regarded as within the limitations of the accuracy of the predictions, the observed differences may also be caused by some form of surface transpor

ISSN:0001-1541    

DOI:10.1002/aic.690140504

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractAn analysis of oxygen absorption by blood flowing through a small oxygen‐permeable fiber in steady state laminar flow is presented. The rigidity and geometry of the fibers eliminate unpredictable shunting and distention, permitting a more detailed analysis of blood‐membrane factors than has previously been undertaken. The mathematical analysis treats the blood as a homogeneous, non‐Newtonian fluid with a reversible nonlinear oxygen sink (erythrocytes). The differential equations are solved numerically and the results of the parametric analysis are presented. The parameters that have a major influence on residence time necessary to obtain a specified oxygen content are the Grashof number, the concentration of hemoglobin in the blood, and wall Nusselt number, γ: γ =DLαL/DMαMIn [1 +tm/R] whereD= diffusion coefficient, α = Bunsen solubility coefficient, subscriptL= liquid in tube, subscriptM= tube material,R= inner radius of tube,tm= tube wall thickness.Comparison of the experimental results to the model indicate that mixing due to the heterogeneous nature of blood is minimal and that the major limitation in oxygen absorption is the blood film. Means of reducing this resistance are

ISSN:0001-1541    

DOI:10.1002/aic.690140505

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractAn analytical solution for the transport equation is presented for the case of coupled energy and multicomponent mass transfer in an ensemble of spherical drops, bubbles or solid particles. The solution is used to evaluate the total interfacial transfer rates in a population with particle size and residence time distributions. Using matrix notation and appropriate transformations, the partial differential equations are solved for each phase by using an integral operator whose kernel is the residence time distribution for the flow system. The method of attack is illustrated by solving the transport equations for fine dispersions or suspensions with high hold‐up values and presence of adventitious surface active agent

ISSN:0001-1541    

DOI:10.1002/aic.690140506

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractSolutions to the momentum and diffusion equations are obtained for rotating disk systems with an imperfect semipermeable interface, with direct application made to the reverse somosis or hyperfiltration process of salt water purification. The equations are solved exactly, and a new technique for solving the momentum equations is described. An approximate solution to the diffusion equation is also obtained which is also applicable to the energy equation, and is shown to be accurate for Prandtl and Schmidt numbers ≥ 1, for a wide range of interfacial mass transfer, for all wedge‐type flows as well as the rotating disk sys

ISSN:0001-1541    

DOI:10.1002/aic.690140507

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractComputer results of the required time to freeze completely a pure liquid in a container shaped like a slab, a cylinder or a sphere are correlated by equations which converge to the asymptotic solutions of the problem. Variables are grouped into dimensionless parameters so that these equations are applicable to any given system.

ISSN:0001-1541    

DOI:10.1002/aic.690140508

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractA boundary layer solution applicable to a certain general type of mass transfer operations was developed by Baasel and Smith (1). When the solution was adapted to the systems of condensation of a vapor from noncondensing gases and absorption of a gas into a wetted wall column, the temperature and interfacial area could not be completely controlled. To overcome these difficulties, the rate of internal dissolution of a hollow cylinder of benzoic acid was experimentally measured and compared to the theoretically predicted values.The ratios of the predicted rates to the observed rates fell, with the exception of two runs out of twenty nine, between 0.622 and 1.303. It was therefore concluded that the finite difference techniques used to obtain a mathematical solution were valid. However, it was observed that the assumption of unidirectional diffusion was possibly not valid. It was concluded that for systems in which the ratio of the total molar density of the fluid to the saturation concentration of the material being transferred was large, in the approximate range of 700 to 2,700, the boundary layer approach corresponded to the Leveque approximation of the classical Graetz solution for heat transfer for fluids with a parabolic velocity distribution.

ISSN:0001-1541    

DOI:10.1002/aic.690140509

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractSeveral methods that can be used to obtain solutions to the laminar boundary layer momentum, energy, and diffusion differential equations for moving continuous flat surfaces with suction and injection are presented. Results are obtained for a wide range of the injection parameter,f(0), at Prandtl and Schmidt numbers of 1, 10, and 100. Those methods which permit hand calculation of the properties of interest are compared using the numerical solutions of the boundary layer differential equations as the exact solutions. The new integral method of Hanson and Richardson which gives results for the momentum thickness that deviate less than 2.2% from the exact values is recommended for predicting values of the momentum boundary layer parameters. The Von Karman‐Pohlhausen method, which was modified to account for suction and injection, is most generally valid. This method gives acceptable values of the transfer coefficients for heat, mass and momentum transfer for most of the values considere

ISSN:0001-1541    

DOI:10.1002/aic.690140510

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY

摘要:

AbstractVapor‐liquid equilibrium data for polar solvent‐hydrocarbon mixtures are relatively plentiful for paraffins and aromatics; they are somewhat less plentiful for olefins. However, almost no data at all have been published for such mixtures wherein the hydrocarbon possesses a triple bond. This paper reports vapor‐pressure measurements of binary mixtures of 1‐hexyne with acetone, acetonitrile, dimethyl carbonate, nitroethane and dimethyl formamide in the temperature range 0 to 70°C. The results are compared with those for polar solvent‐hydrocarbon mixtures wherein the hydrocarbon is paraffinic, olefinic, o

ISSN:0001-1541    

DOI:10.1002/aic.690140511

出版商:American Institute of Chemical Engineers    

年代:1968

数据来源: WILEY