摘要:

AbstractModels for the laminar sublayer of turbulent pipe flow are reviewed. The observations of the sublayer by Popovich and Hummel and the experimental fluctuation frequencies obtained by Shaw and Hanratty are used with the models to evaluate experimental heat and mass transfer data. The eddy diffusivity model and a parallel conductance model appear to be consistent with the experimental data.

ISSN:0001-1541    

DOI:10.1002/aic.690170113

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractThe effects of aliphatic alcohols on mass transfer and drag coefficients of a carbon dioxide bubble were investigated in very dilute aqueous solutions. A high speed photography technique provided an almost continuous record of the bubble volume, shape, and oscillation, as related to the height of the bubble in the liquid and the time elapsed from the moment of its release. The results showed that the concentration, molecular size, and structure of the investigated alcohols have a pronounced effect on mass transfer as well as drag coefficients of the rising bubble. The significance of these effects with respect to idealized models of a highly circulating bubble and a solid sphere was considered, and a functional relationship was found to exist. This relationship may be applied to systems more complex than a single bubble.

ISSN:0001-1541    

DOI:10.1002/aic.690170114

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractThe multicomponent distillation problem is formulated so that unknown compositions do not appear explicitly either in the equilibrium and material balance equations or in the heat balance equations. Use of this formulation in absolute iteration as well as Newton‐Raphson iteration is discussed. Other types of staged separation processes may be similarly expresse

ISSN:0001-1541    

DOI:10.1002/aic.690170115

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractConvective diffusion of heat is a problem which arises in many areas. Since most thermal transport situations involve more than one material insulation, supports, etc., the treatment of composite regions is of interest. In certain systems, namely, those involving chemical or nuclear reactions, heat generation may be either localized or distributed. In this paper a general analytical treatment of this problem is made by using a double Fourier series technique involving an extended orthogonality concept. This treatment is then applied to the solutions of heat transfer situations arising in electrochemical energy conversion systems. Experimental temperature profiles are presented which test the theory.

ISSN:0001-1541    

DOI:10.1002/aic.690170116

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractA steady state experimental technique for measuring fluxes of the components and diffusivities in binary liquid systems has been developed. Steady state diffusion is established through a sintered glass diaphragm of ultrafine porosity with a known concentration difference across the diaphragm. The concentrations are maintained by a flow of solution on one side of the diaphragm and an infinite sink on the other side. The fluxes and diffusivities are calculated from the measured flows and compositions. A syringe pump capable of delivering extremely small flow rates with good reproducibility is used to pump the solution past the sintered glass diaphragm. The diffusion cell design permits an accurate control of pressure drop across the diaphragm so that fluxes can be measured both with and without pressure gradients. The diffusion cell was calibrated by using the hydrochloric acid‐water system.Three binary systems, ethanol‐benzene, aniline‐benzene, and aniline‐carbon tetrachloride were chosen for diffusion studies. Diffusivity‐composition data for these systems at 25°C. were used to test the existing correlations for the concentration dependence of binary diffusivity. Of these, the empirical correlation of Vignes (11) represents the data satisfactorily. In addition, experimental molar diffusion flux ratio data for the above systems at 25°C. with no pressure gradients are reported and found to be essentially equal to the ratio of molar volumes of the

ISSN:0001-1541    

DOI:10.1002/aic.690170117

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractThe effect of viscosity and diffusivity variations on concentration polarization during the ultrafiltration of protein solutions in two‐dimensional stagnation flows is investigated by numerical integration of the equations of continuity and motion. It is found that these effects are surprisingly small and insensitive to the forms of concentration dependence postulated. The high Schmidt numbers and low permeation rates characteristic of these systems result in considerable simplification of the analysis and permit use of a modified Chilton‐Colburn relation for predicting the onset of sludge formation at the membrane‐solution interface. The predicted dependence on Schmidt number agrees with published experimental data for other boundary‐layer flows and suggests the possibility of improved prediction of equipment perf

ISSN:0001-1541    

DOI:10.1002/aic.690170118

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractVapor‐liquid equilibria data for the hydrogen‐propane binary system and the hydrogen‐carbon monoxide‐propane system were taken at temperature of −185° to +75°. and under pressures as high as 3000 psi. Vapor‐liquid data for the hydrogen‐carbon monoxide‐propane system are reported at −50°, 0°, and +50°. at pressures of 500, 1000, and 2000 lb./sq.in. abs. for each of the three temperatures. The Krichevsky‐Kasarnovsky equation adequately correlated the solubility data of hydrogen in the liquid phase of the hydrogen‐propane system. Hydrogen‐propane data are compared with the

ISSN:0001-1541    

DOI:10.1002/aic.690170119

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractThis paper presents the results of theoretical and experimental studies of the dynamic effects of varying the location of the temperature control tray in a distillation column. The binary methanol‐water system was studied in a 24‐tray, 8‐in. I.D. column with reflux manipulated to hold the temperature on various trays in the rectifying section of the column.The ultimate gain and ultimate frequency of the temperature feedback control loops were found to decrease as the temperature control tray was moved down the column away from the top. This confirmed the qualitative statements made by many workers and the quantitative work recently reported by Beaverstock.The process natural frequency (or breakpoint frequency) was found, unexpectedly, to increase somewhat as the temperature control tray was moved down the column. This meant that the open‐loop response of tray liquid composition to reflux flow changes was slightly slower for trays near the top of the column. Because of the increasing purity near the top, adjacent trays differed little in composition and the slope of the equilibrium line was flatter. Both contributed to slower dynamic response.In developing a theoretical model for the real system studied, the linear model and solution techniques of Lamb, Pigford, and Rippin and were extended to include nonequimolal overflow

ISSN:0001-1541    

DOI:10.1002/aic.690170120

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractThis study concerns the transient response of a tubular reactor in which a second‐order reaction takes place under isothermal conditions. The reaction studied was the saponification of methyl acetate with sodium hydroxide. Experimental data were obtained in a tubular reactor for flow upsets.Theoretical models using residence time distribution (RTD) techniques have been developed. The study was conducted at 36°C. The reactor was a 13‐ft. long, ¼‐in. diam. copper tube in the form of a spiral with a volume of 110 cc.The agreement obtained between the experimental data and the RTD model predictions was good, verifying that this model is satisfactory for simulation of tubular reactor dynamics. Backmixing was observed in the reactor. This nonideality was accounted for empirically in the RTD model, since backmixing was observed to be mainly a function of fl

ISSN:0001-1541    

DOI:10.1002/aic.690170121

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY

摘要:

AbstractAnalyses of stretching of a viscoelastic liquid have been interpreted as showing that there is a maximum stretch rate to which the material can be subjected, and several physical phenomena have been explained on this basis. It is shown here theoretically and experimentally that the concept of a limiting stretch rate does not have general validity.

ISSN:0001-1541    

DOI:10.1002/aic.690170122

出版商:American Institute of Chemical Engineers    

年代:1971

数据来源: WILEY