摘要:

Combustion research, long dominated by mechanical engineers, is becoming increasingly a chemical engineering application. It is therefore desirable to have a well defined reactor in which to conduct combustion chemistry studies. A two zone laboratory reactor emulating a perfectly stirred reactor + plug flow reactor (PSR + PFR) sequence has been constructed and validated for use in high temperature normal and staged combustion studies. A premixed fuel/eed enters the backmixed primary zone. The effluent mixes with additional injected oxidant and/or steam, and then enters the linear flow secondary zone. Extracted gas samples from cooled probes located in each zone are subjected to several dedicated on-line stack gas analyzers, and separation/analyses by on-line gas chromatography. Detailed reaction mechanisms from the literature are incorporated into a PSR + PFR reactor engineering model. The experimental feed rates and measured temperatures are also input to the model. Good comparisons between model predictions and experimental data have been obtained for normal and air-staged combustion studies. Rate-of-prod,uction calculations from the modeling offers helpful insight into the reaction pathways responsible for important species, especially pollutants.

ISSN:0098-6445    

DOI:10.1080/00986449608936465

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Experimental kinetic data have been obtained for the CO oxidation reaction over laboratory made platina-rhodium monolithic catalyst. Inert layers ofy-yalumina were deposited over the active layer in order to elucidate the diffusional effects on the monolithic catalyst. A synthetic gas mixture consisting of CO1, O2and N2was the feed of an integral tubular reactor between 180 and 370°C. A first order kinetic rate expression with respect to CO concentration, which includes an inhibition term of second order was found to fit the experimental data via a model which also accounts for diffusional resistances. The obtained kinetic and diffusional data can be used in the design of a catalytic converter with improved efficiency. The results can also be used to interpret the diffusion mechanism inside the catalyst itself and it was concluded that Knudsen diffusion mechanism prevails.

ISSN:0098-6445    

DOI:10.1080/00986449608936466

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The stopped-flow spectrophotomctric method was applied to study the kinetics of the ozonation of o-cresol in aqueous solutions of pH values varying from 2 to 9 at 10 to 40°C. The fast reaction between o-cresol and ozone is second order overall with first order in each reactant. The ozonation rale increases with the temperature and pH value of the solution. In neutral solutions, the overall rate constant increases from 422,000 M-1S-1at 10°C to 1,549,000 M-1S-1at 40°C. The activation energy is about 30 KJ/mol in the neutral solutions; it increases slightly with the acidity of the solution.

ISSN:0098-6445    

DOI:10.1080/00986449608936467

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The aim of the research project presented in this paper is to devise a process to treat waste liquors from the pickling of iron or steel with hydrochloric acid in rolling mills, recovering the high iron content in the form of oxides or oxyhydroxides which can later be used in other industrial processes. In addition to reducing water pollution, such a process attaches a new value to this ferrous waste.

ISSN:0098-6445    

DOI:10.1080/00986449608936468

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Since Sideman et al.[1]derived an analytical solution of the Nusselt number for a spherical drop in the direct contact evaporation in an immiscible liquid, many researchers have performed theoretical research on this field under different assumptions [2]-[6]. However drops moving in another immiscible liquid do not take a spherical form, but oblate form, which may be well approximated as an ellipsoid. This paper establishes the mathematical model of heat transfer for a moving ellipsoidal drop in an immiscible liquid, and presents results from numerical calculation. The relationship of the Nusselt number with the Weber number and the Peclet number is given, which is suitable for a relatively large range ofWeandPe. The theoretical results for the Nusselt number show good agreement with experimental data. Some important conclusions are obtained.

ISSN:0098-6445    

DOI:10.1080/00986449608936469

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper deals with the application of some chemical reaction engineering principles in order to develop a supported liquid phase reagent (SLPR) able to dechlorinate PCBs contained in highly viscous media. The reagent consists of polyethyleneglycols containing a dissolved base and a radical initiator. Recently this mixture was proposed as CDP(R)(Chemical Dechlorination Process) for PCBs detoxification. In this paper are reported several experimental tests designed to optimise configuration of reagents on inert support to dechlorinate the PCBs contained in the transformer oil. The main results are: the evaluation of optimum reagent load on support, the set up of dechlorination kinetics of commercial PCBs as AROCLOR 1260 in transformer oil tested in the 50-2500 ppm range. SLPR was tested in a “fixed-bed” as well as in “slurry” reactor configurations. The above results were used to design two mobile plants for on-site treatments.

ISSN:0098-6445    

DOI:10.1080/00986449608936470

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In previous papers, the author considered the critical or the extremum points of the entropy production rate in insulations with one-dimensional heat conduction, either alone or associated with other refrigerating systems necessary to maintain the steady state.

ISSN:0098-6445    

DOI:10.1080/00986449608936471

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A transparent computer-controlled multizone furnace is used to study the interface control of the vertical Bridgman crystal growth. Sodium nitrate is chosen as a model material. The effects of heating profiles and growth speeds on the interface shape during steady-state growth are illustrated. It is observed that the growth front becomes more concave with the increasing growth speed and with decreasing axial temperature gradients near the growth front. When a suitable combination of the growth speed and the heating profile is used, a flat or slightly convex interface can be easily obtained. Numerical simulation is also conducted, and the calculated interface shape and position under various growth conditions are in good agreement with the observed ones.

ISSN:0098-6445    

DOI:10.1080/00986449608936472

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A new model for approach processes of two unequal or equal sized drops or bubbles is proposed based on a parallel film concept and energy conservation analysis. This model can estimate the interaction time and the maximum film area for an approach and the effects of Weber number, size ratio and curvature of film. It also gives a good explanation why the effective virtual mass coefficienl in the model of Chesters and Hofman (1982) changes with the size ratio of drops or bubbles.

ISSN:0098-6445    

DOI:10.1080/00986449608936473

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The onset of thermal convection in a translucent porous layer is considered. Attention is focused on the effect of radiative heat transfer on the critical Rayleigh-Darcy number and the convection cell shape. If we consider the contribution of radiative heat transfer, the basic temperature profile is non-linear and the thermal convective instability is influenced by the ratio of conduction to radiation heat flux, the temperatures at the boundary surfaces, and radiative parameters such as wall emissivity, scattering albedo and extinction coefficient as well as the usual Rayleigh-Darcy number. Effects of these parameters on the onset of convective instability are investigated with the help of linear stability theory employing the Darcy's law and the radiative transport equation simplified by the P1approximation. The increased effective thermal conductivity due lo the radiation inhibits the onset of convection and causes increased critical Rayleigh-Darcy number and decreased convection cell size. The results of the present work may be exploited to find out the optimal diameter of aerogel pellets and the air pressure in the double pane window filled with the translucent silica aerogel granules to suppress natural convection.

ISSN:0098-6445    

DOI:10.1080/00986449608936474

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor