摘要:

AbstractAn investigation has been carried out on velocity profiles of Newtonian liquids at the exit of circular tubes for Reynolds numbers from about 50 to 1000. A simple expression which asymptotically approaches a Poiseuille parabolic distribution for higher Reynolds numbers is obtained. Experimental measurements of extrudate swell ratios were used as criteria for convergence to the solution. Comparison with jet shapes from previous experimental and theoretical studies supports the obtained results. The work also illustrates a straightforward method for simplifying and solving the governing equations for laminar flows of thin liquid layers.

ISSN:0008-4034    

DOI:10.1002/cjce.5450650102

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn experimental technique to eliminate the effects of sensor dynamics when a tracer is used to measure the hydrodynamics of a turbulent bed contactor is described. The resulting liquid holdup data are compared both with predictions from the pressure drop measurements and with the available correlations in the literature. The results show that the pressure drop method and Handl's (1976) equation under‐predict liquid holdup, while Rama et al.'s (1983) and Kito et al.'s (1978) equations over‐predict the resu

ISSN:0008-4034    

DOI:10.1002/cjce.5450650103

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

年代:1987

数据来源: WILEY

摘要:

AbstractA simple modification of the Van Driest damping factor for mixing length calculations of mass and/or heat transfer coefficients at solid boundaries is proposed to increase mass eddy diffusivities in the near‐wall region, without affecting velocity predictions. Calculated mass transfer rates with a constantSct= 0.85 are in good agreement with present and previous experimental results obtained in pipe and duct flows at high Schmidt number

ISSN:0008-4034    

DOI:10.1002/cjce.5450650104

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

年代:1987

数据来源: WILEY

摘要:

AbstractTo confirm the theory for gas absorption accompanied by an instantaneous irreversible reaction in laminar falling films of power‐law liquids which was presented in a previous paper, experiments were carried out on the absorption of pure carbon dioxide into aqueous kaolin slurries containing sodium hydroxide by using a long wetted‐wall column. The experimental data were in fairly good agreement with the theoretical predictions, the average deviation being 3.0%. The discussion on the effect of the power‐law index of the liquid upon the reaction factor suggested an approximate method of estimating the reaction factors for power‐law

ISSN:0008-4034    

DOI:10.1002/cjce.5450650105

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

年代:1987

数据来源: WILEY

摘要:

AbstractAbsorption of sulfur dioxide accompanied by reversible reaction in dimethylaniline has been studied using a short falling‐film apparatus. Solutions of the amine in kerosene were used for this purpose. The effects of gas and liquid concentrations, contact time and temperature on the rate of absorption were investigated. Reaction equilibrium constant values were obtained at different temperatures from separate measurement of solubility of sulfur dioxide gas in kerosene as well as in dimethylaniline solutions. The heat of reaction was also calculated from these data. The absorption data could be satisfactorily interpreted by using the penetration theory of mass transfer with simultaneous pseudofirst order chemical reaction. The rate equations for the forward and reverse reactions were establishe

ISSN:0008-4034    

DOI:10.1002/cjce.5450650106

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn approximate procedure for solving the problem of temperature optimal control distributed in both space and time coordinates is presented. It is applied to chemical reactors suffering from catalyst decay whose model is described by a complex second order partial differential equation deduced from LHHW kinetics. The proposed algorithm uses a finite‐difference approximation method to solve the state equation, and the control vector parametrization technique to obtain the optimal control. Numerical examples are computed and the results obtained show that distributed control reaches significantly higher production than lumped contro

ISSN:0008-4034    

DOI:10.1002/cjce.5450650107

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

年代:1987

数据来源: WILEY

摘要:

AbstractA recycle reactor system has been developed to measure the activities of catalysts for isotope exchange between hydrogen gas and water vapour. To allow testing of reasonably large quantities of catalysts, the reactor was operated with a high recirculating flow of hydrogen gas passing through a saturator to provide the water vapour required for the reaction. In this mode of operation, only a small spiking gas flow was required as feed compared to the very high feed flow that would be required for once‐through operation. The reactor was also operated as a trickle bed by recirculating the saturator water. By testing catalysts under both vapour and trickle bed modes, it was possible to investigate the effect of trickling water over the catalyst on the catalytic activity.Kinetic exchange rates under vapour phase operation were calculated from both plug flow and well‐mixed reactor models. The former model was found to be the appropriate one for the ranges of operating conditions investigated. However, for trickle bed operation, the well‐mixed reactor model was found to be the suitable one.Vapour phase and trickle bed tests done with random bed and structured bed catalysts indicated that the gas phase isotope exchange reaction was not impaired by the presence of liquid water in the re

ISSN:0008-4034    

DOI:10.1002/cjce.5450650108

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

年代:1987

数据来源: WILEY

摘要:

AbstractAbsorption of oxygen into 0.09 – 0.7 M solutions of ammonium sulfite was measured by utilizing a stirred cell. The concentration ranges of the cobalt sulfate catalyst was 5.5 × 10−5– 4.7 × 10−3M and that of oxygen in the gas phase 21 – 100%. The theory of absorption with fast pseudo‐nth order reaction was used to find the order of intrinsic rate of reaction with respect to reactants and the catalyst. Above a critical sulfite concentration the order in sulfite is zero, in O2is 0.4 – 1, and in CoSO4is 1. Under those conditions a proposed reaction mechanism yields orders of zero, 1, and 1, respectively. Below the critical point the order in sulfite is 2, indicating that another reaction mechanism is applicable. Although an increase of the ionic strength enhances the reaction rate slightly, an increase of pH from 7.6 to 8.5 causes a 1.4 fold increase. Under oxidative conditions deactivation of the catalyst and insoluble precipitate format

ISSN:0008-4034    

DOI:10.1002/cjce.5450650109

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

年代:1987

数据来源: WILEY

摘要:

AbstractA model for the dehydrogenation of methylcyclohexane in a tubular reactor over an industrial catalyst Pt‐Sn/Al2O3has been established. This model takes into account the axial dispersion at the inlet of the catalytic bed reactor as well as the heat transfer at the wall of the reactor. The heat transfer at the wall is satisfactorily represented by using a heat transfer coefficient correlation for which the parameters are obtained by fitting to the experimental data. The model provides a good representation of the radial and axial temperature profiles in the packed bed and can be also used to calculate the conversio

ISSN:0008-4034    

DOI:10.1002/cjce.5450650110

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

年代:1987

数据来源: WILEY

摘要:

AbstractJet‐mixers are known as devices capable of greatly enhancing the gas‐liquid interfacial areas. Their application to chemical reactions is discussed in this paper. The oxidation of phenols in aqueous media is considered.Rates of oxidation fifty times higher than those previously observed can be achieved through a jet‐mixer discharging a fine mist into the reactor side operating at plug flow regime. The presence of hydrogen peroxide accelerates the oxidation. Kinetic information is pro

ISSN:0008-4034    

DOI:10.1002/cjce.5450650111

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

年代:1987

数据来源: WILEY