摘要:

An approximation formula for finite Sturm-Liouville integral transforms of nonlinear functions allows determination of approximate analytical solutions to a certain class of nonlinear boundary value problems. The proposed method is extremely powerful in analysis of a variety of chemical engineering models. The influence of the degree of nonlinearity of the nonlinear term on results obtained using the approximate transform formula is investigated numerically. An iterative procedure in transform space is described for improving solution accuracy, and fast convergence is observed in three illustrative examples. The technique yields solutions which can be related to bounds on the exact solution derived by Kalaba. The asymptotic solution for the mode error, which is the error in approximating the nonlinear function in transform space, is obtained analytically.

ISSN:0098-6445    

DOI:10.1080/00986448608911319

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Hydrodynamic coupling between a fluid and a planar piezoelectric crystal operating in the thickness shear mode provides a powerful, yet remarkably simple means to characterize fluid properties. Equations describing hydrodynamic coupling are developed for Newtonian fluids. This analysis takes into account, for the first time, the influence of a nonuniform piezoelectric crystal surface velocity. In particular, a Gaussian velocity distribution, suggested by other work, yields a functional relationship between hydrodynamic coupling and the fluid viscosity/density product that is in agreement with experiment. Beginning with these results, analytical methods for measuring individually the fluid visocity and density are described. Finally, it is demonstrated experimentally that the automatic gain control from the piezoelectric crystal oscillation circuit provides a ready means of fluid property characterization.

ISSN:0098-6445    

DOI:10.1080/00986448608911320

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Forced concentration cycling was used to study the feasibility of rate and selectivity enhancement in FT synthesis. Our results indicate that it is possible to increase the time averaged rate of reaction by as much as 210% over the equivalent steady state rate. The improvements in selectivity are more complex. In general concentration cycling leads to increased rates of methane production. Under certain operating conditions it is possible to enhance the selectivity to propane by as much as 400% over the equivalent steady state rate. Selectivity enhancements for ethane and butane were also observed

ISSN:0098-6445    

DOI:10.1080/00986448608911321

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The aim of the investigations was to determine the drag reduction produced by polymer additives in the hydraulic transport of coal. As no systematic results were available in the literature, experiments were undertaken using a wide range of flow velocities and polymer concentrations (up to 440 ppm) to obtain a clear picture about the processes involved. Special attention was paid to the effects of polymer degradation. The experiments were carried out on two different facilities for hydraulic transport with pipe diameters of 40 and 250 mm

ISSN:0098-6445    

DOI:10.1080/00986448608911322

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The transient behavior for natural convection heat transfer within a vertical cylindrical enclosure was studied using the SIMPLER numerical algorithm. Initially, the temperature of the internal fluid was uniform. The unsteady state heat transfer was initiated by a temperature step change applied to all boundaries. The boundary temperature was then increased at the same rate as the center temperature until pseudosteady state was achieved. (Pseudosteady state is comparable to steady state convection for a fluid with uniform heat generation.) The transient heat transfer coefficient and the intensity of flow, along with the magnitude and the location of the minimum temperature, mean temperature, and maximum stream function are presented. Temperature and stream function contours are used to show the penetration of heat from the boundary and the development of the flow patterns. The local Nusselt number is also provided as supplementary information. A cylinder with HID = 1 was considered, with the Prandtl number of the fluid equal to 7 and a Rayleigh number of 105. A characteristic length defined as 6 x (volume)/(surface area), which was found to produce the best regression results in our previous studies, was used in defining the Nusselt number and the Rayleigh number. The initial heat transfer rate was found to be correlated by

ISSN:0098-6445    

DOI:10.1080/00986448608911323

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Mathematical models of packed-bed catalytic reactors are aimed to predict the conversions and temperature profiles in both fluid and solid phases within the reactor. Although very general models can be mathematically formulated, usually several simplifying hypothesis are introduced for the fluid phase and/or the solid phase, in order to overcome computational difficulties

ISSN:0098-6445    

DOI:10.1080/00986448608911324

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A modified Lee-Kesler equation of state has been proposed to improve the accuracy for the subcooled and saturated liquid regions of normal fluids. It is further extended to polar fluids by the addition of a fourth parameter X. The extended equation has been found to be reliable over a wide vapor and liquid regions for polar fluids and it is easy for computer use. Fourteen kinds of normal fluids and twelve kinds of polar fluids have been tested. The total average absolute deviations for the normal fluids and polar fluids are 0.79% and 1.68% over the range ofTr= 0.3 to 4 andPr- 0.01 to 10.

ISSN:0098-6445    

DOI:10.1080/00986448608911325

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A, theoretical, study, of, coupled, heat, transfer, to, ablative, preheated, graphite, cone, shaped, surfaces, in, supersonic, CO2-N2, gas, streams, is, presented., Various, CO2, free-stream, concentrations, and, a, wide, range, of, surface, temperatures, (1000-2500°K), for, which, the, surface, chemical, reactions, are, diffusion, controlled, are, considered., Thermodynamic, coupling, effects, (i.e., thermal-diffusion, and, diffusion-thermo), are, accounted, for, and, the, relative, importance, of, these, effects, to, the, overall, surface, heat, flux, is, analyzed., The, present, results, indicate, that, the, relative, contributions, of, thermodynamic, coupling, effects, to, the, surface, heat, flux, are, most, pronounced, for, large, CO2, free, stream, concentrations, and, at, lower, temperatures, (close, to, 1000°K, It, is, also, shown, that, the, present, trinary, CO2, CO, N2, system,, without, causing, significant, errors, (˜1%), to, the, calculated, surface, heat, fluxes,, can, be, treated, as, a, binary, system, in, which, CO, +, N2, are, considered, ‘one’, combined, species.

ISSN:0098-6445    

DOI:10.1080/00986448608911326

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effect of additive solutes in air/water aerated mixing vessel over a wide range of operation conditions was investigated. Then-dodecane with negative spreading coefficient reduced the mass transfer capability; and the sodium dodecyl sulfate increased it; however, the ethanol exhibited no difference inKLainitially and then enhanced it linearly proportional to its volume fraction. In these air-water-additive systems, correlative equations were also proposed.

ISSN:0098-6445    

DOI:10.1080/00986448608911327

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effect of solids concentration on the bubble to bubble-slug, bubble-slug to slug, and slug to churn flow transitions in gas-liquid-solid vertical flow has been studied using air, water, and glass beads in a 5 cm ID plexiglass column. Several simple models to predict the transitions were developed utilizing criteria proposed for gas-liquid vertical flow. These criteria are shown to apply equally well in the absence or presence of the solid phase

ISSN:0098-6445    

DOI:10.1080/00986448608911328

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor