摘要:

This paper examined the evaporation and condensation of the reaction mixture within the trickle bed reactor during 1,5-cyclooctadiene hydrogenation. The aim of study has been to formulate a mathematical model of heat and mass transfer influenced the exothermic reaction of a volatile reaction mixture apt to evaporation by the reaction heat in the system which is often accompanied by a hot spot temperature formation in the reactor followed by the enhancement of undesirable side reactions and/or catalyst deactivation. The numerical solution of the proposed model agreed quite well with the experimental temperature profiles in the trickle bed reactor.

ISSN:0098-6445    

DOI:10.1080/00986448608911696

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A computer graphics program developed for the IBM PC calculates equilibrium and operating lines and steps off the number of stages on screen using the McCabe-Thiele method. The results are obtained by graphics, not by numerical methods, so that the accuracy depends upon the screen resolution or pixel density. The equilibrium line is drawn from bubble-point temperature calculations using constants from the Wilson and Antoine equations. The operating lines and staircase are constructed by computer graphics according to the prescribed operating parameters. Design variables, which include the reflux ratio, quality of feed, Murphree efficiency, product purities and pressure, may be changed interactively.

ISSN:0098-6445    

DOI:10.1080/00986448608911697

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Upper and lower reciprocal variational principles have been used to estimate the effective conductivity (or diflusivity)across beds of randomly dispersed fibers with orientations distributed in two and three dimensions. Estimated thermal conductivities of fiber glass insulation, graphite-epoxy fiber reinforced composite materials, as well as the diffusivities of several fibrous materials agree well with measured values.

ISSN:0098-6445    

DOI:10.1080/00986448608911698

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Butoxysiloxanes are prepared by reacting SiCl4with 1-butanol and 1-butanol-water mixtures in the liquid phase at atmospheric pressure. Some of their physical properties such as density, refractive index, viscosity, viscosity-temperature-coefficient (VTC) viscosity index (VI) dielectric constant (e) dielectric loss (ϵ”) molar polarization (Pm) induced polarization (Pi) orientation polarization (Po), molar polarizability (α0) relaxation time (τ)and Batschinsky's constant (ω)are evaluated. Some of the values are compared with those of commercial grade linear polydimethylsiloxanes, cyclic polydimethylsiloxanes and petroleum oils. Viscosity-temperature and viscosity-pressure characteristics, thermal and oxidation stability of butaoxysiloxanes indicate that these could be useful substitutes for commercial grade silicones in some engineering applications.

ISSN:0098-6445    

DOI:10.1080/00986448608911699

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The diffusion and transport of a gas species is analyzed for a slowly pulsating fluid in laminar tube flow. It is assumed that the fluid velocity is in phase with the pulsating pressure gradient. A reversible chemical reaction within the fluid is modeled using advancing front theory. The pulsation is assumed to affect only the diffusion boundary layer thickness, which may be out of phase with the flow pulsation. The solution is approximate for small perturbations of the boundary layer thickness. With these assumptions a closed form solution for the bulk transport is obtained. The results are expressed as differences in the bulk transport relative to a steady flow having the same average flow conditions. The pulsation effect is expressed as a function of the non-dimensional flow amplitude and frequency parameters for various average conditions. Comparison with experimental measurements of oxygen diffusing into water and hemoglobin solutions shows good agreement. For the range of parameters used for the measurements, there is no effect of the pulsation on time-averaged transfer rates.

ISSN:0098-6445    

DOI:10.1080/00986448608911700

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Application of forced oscillations to chemical reactor systems is investigated for three systems based on: (1)a homogeneous/heterogeneous reaction mechanism proposed by Horn and Bailey (1968) (2)amine and alcohol reactions on oxide catalysts and (3)cobalt catalyzed CO methanation. Previous analyses of these systems have demonstrated experimentally and/or theoretically, significant enhancements in reactor performance upon periodic operation. For the three cases investigated, computer-simulated modelling confirms great improvements in reactor performance upon periodic concentration forcing: (1)30% enhancement in selectivity, (2)50 fold increase in reaction rate and (3)13 fold improvement in conversion, respectively. However, it is also observed that yield improvements in these systems do not exceed or even match the performance obtained under optimal steady state conditions.

ISSN:0098-6445    

DOI:10.1080/00986448608911701

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The successful development of the ideal adsorbed solution theory to estimate multicomponent adsorption equilibria for systems such as granular activated carbon-dilute aqueous solution of organics has necessitated the formulation of algorithms which incorporate the IAS theory in adsorption calculations. Although the IAS theory defines the equilibrium relation not by explicit expressions but through a system of equations, this apparent difficulty does not prove to be insurmountable. The procedures established in this work cover the situations most likely encountered in adsorption calculations, in which the use of the equilibrium relationship is invoked.

ISSN:0098-6445    

DOI:10.1080/00986448608911702

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This work explores the use of variable measurement and control structures in the state estimation and control of distillation processes. Distillation processes with complex behavior are difficult to control (azeotropic and extractive separation) due to the existence of sharp temperature gradients and were found to be ideal candidates for the implementation of variable control structures. An on-line sequential analysis of the temperature measurements along the length of the column allows a fast selection of the best measurements to be used in low order, simple and robust control schemes. Overall results indicate that variations in column operating conditions could also cause variations in the resulting control schemes. For the case of extractive distillation, more robust estimation and control were obtained through the use of the proposed methodology.

ISSN:0098-6445    

DOI:10.1080/00986448608911703

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A detailed mathematical model is developed for the transport controlled thermal decomposition of solids, which is based on the dusty-gas model for describing the diffusion and flow of gases in the porous product layer surrounding the unreacted shrinking core. The earlier models employ Fickian type flux relations and neglect pressure gradients within the particle. These pressure gradients are shown to be significant in such reactions and affect the overall rates of decomposition. Spherical limestone particles of approximately 4 cm diameter were calcined at 950°C in order to test the proposed model. The theoretical predictions compare well with the experimental results and are also better than the predictions provided by the effective diflusivity based Fickian models.

ISSN:0098-6445    

DOI:10.1080/00986448608911704

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The growth of an isolated, stationary gas bubble in a glassmelt is analyzed accounting for the motion of the boundary and the motion of the liquid. The growth of a gas bubble which initally consists of carbon dioxide is studied in a glassmelt whose gaseous composition consists of water vapor, carbon dioxide, sulfide, oxygen and nitrogen. Results obtained by means of a finite difference formulation are presented for the bubble radius, and pressure and composition as a function of time. It is shown that at large times the bubble radius is a linear function of time, and that the bubble pressure is a monotonically decreasing function of time. The distribution of the gaseous species in the glassmelt is also presented as a function of the distance from the bubble surface and of time. It is shown that carbon dioxide and nitrogen diffuse from and to the bubble, respectively, while the other species do not play an important role in the bubble growth. Comparisons between a quasi-stationary approximation and the full transient solution indicate that the boundary motion slows the rate of bubble growth at long times.

ISSN:0098-6445    

DOI:10.1080/00986448608911705

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor