摘要:

The inlet and outlet streams of a chemical reactor may reach a steady state before the internal distributions of concentration, etc. have come to the steady state. Such a steady state, in which the reactor is viewed only as a system with certain inputs and outputs, may be called the black-box steady state (BBSS). The existence of a BBSS does not always imply that of a true SS, and the BBSS may be attained in a finite time even though the SS is only attained asymptotically. Indeed under some circumstances the BBSS can be achieved immediately upon start-up. Provided that the internal transients are not catastrophic, the practical, or operator's, concept of a steady state is really that of a BBSS.

ISSN:0098-6445    

DOI:10.1080/00986447508960441

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Results are presented for a numerical investigation of a technique for calculating the time optimal control of linear systems with multiple inputs. The objective is to produce a technique generally applicable to linear systems. The technique was based upon the subsidiary problem derived using the methods of functional analysis and was previously thought to have advantages over other techniques because the solution of the subsidiary problem involves minimizing a function of several variables for which proven algorithms were available.

ISSN:0098-6445    

DOI:10.1080/00986447508960442

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

This paper examines the effect of simultaneous heat and mass transfer on the hydrogenation of cyclohexene in a trickle bed reactor with particular attention given to the problem of liquid phase evaporation and transition to the gas-phase regime of operation. The reaction rates are obtained as a function of temperature and hydrogen flow rate; the concentration of the substrate in the feed displays considerable hysteresis due to an abrupt increase of the reaction rate arising from temperature gradients within the bed and in the gas film surrounding the catalyst pellet, during the transition from the liquid to the gas-phase regime. The transition is accompanied by the change of apparent kinetics of the model reaction as well as by a change of regime and operation of the pellet. In the liquid phase a pellet originally showing inter-phase and intra-particle diffusion resistances changes into the gas-phase regime with a large resistance due to inter-phase diffusion.

ISSN:0098-6445    

DOI:10.1080/00986447508960443

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The linear stability of radially bounded thinning free films is examined for the case in which the surfaces of the film are initially plane and parallel. The two-dimensional time-dependent drainage flow computed by lubrication theory constitutes the base state. The linear stability of this flow with respect to axially symmetric varicose disturbance is treated in the quasistatic approximation. For thin films, disperse London-van der Waals attractive forces play a key role in determining the critical thickness at rupture, and the results are presented as predictions of critical film aspect ratio as a function of two dimensionless groups which are ratios of the important physical-chemical forces on the film. Predicted critical thicknesses are seen to agree well with the limited available experimental data.

ISSN:0098-6445    

DOI:10.1080/00986447508960444

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

An enzyme immobilization technique employing enzyme sequestration within the porous support regions of asymmetric hollow fiber membranes is described and experimentally evaluated. Reactor conversion data over a wide range of operating conditions agrees well with predictions obtained from a mathematical model developed previously. β-galactosidase immobilized by this technique was found to retain 100% activity for 60 hours of continuous reactor operation, and for 140 days when stored at 3°C. The effects on reactor performance of (1) enzyme adsorption by the membrane, and (2) axial redistribution of enzyme accompanying radial flow of fluid through the fiber wall, have been evaluated; neither process significantly alters conversion kinetics or efficiency for the substrate/enzyme system investigated.

ISSN:0098-6445    

DOI:10.1080/00986447508960445

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0098-6445    

DOI:10.1080/00986447508960446

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

An a priori analysis of the Wilson and NRTL equations is carried out. The possibilities whether these equations are suitable for the simultaneous description of the excess Gibbs energy GEand the excess enthalpy HEare investigated. It follows from this analysis that the Wilson equation for strongly non-ideal solutions is not capable of quantitative describing simultaneously the functions GEand HE. The applicability of the NRTL equation is restricted by its impossibility of changing the sign of the excess entropy in the permissible concentration region (0, 1).

ISSN:0098-6445    

DOI:10.1080/00986447508960447

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor