Wyniki wyszukiwania - BazTech

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Metodyka przygotowania próbek polimerowego materiału gradientowego do badań mikroskopowych

Stabik J., Chomiak M., Suchoń Ł.

Przetwórstwo Tworzyw

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2012

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[R.] 18, nr 4

356-360

PL

W artykule omówiono zagadnienia przygotowania powierzchni próbek polimerowego materiału gradientowego do badań mikroskopowych. Próbki wykorzystane do badań wykonane były z żywicy epoksydowej jako materiału osnowy oraz proszku węgla kamiennego jako napełniacza. Kompozyty wytworzono stosując metodę odlewania odśrodkowego. Na podstawie analizy zdjęć mikroskopowych wybrano metodę pozwalającą na obserwacje próbek na mikroskopie świetlnym. Badania wykazały, że procedura szlifowania papierem ściernym a następnie polerowania na mokro, bez użycia materiału ściernego, pozwala na uzyskanie zdjęć mikroskopowych o najlepszej jakości z dobrze widocznymi ziarnami napełniacza.

EN

The article discusses the issues of surface preparation of polymeric gradient material for microscopic examination. Specimens used for research were made of epoxy resin as a matrix and coal powder as a filler. The composites were prepared using centrifugal casting method. The selected method allows the observation of the specimens using light microscopy on the basis of the analysis of microscopic images. Research has shown that the procedure of grinding with abrasive paper and then wet polishing, without the use of abrasive, allows to obtain microscopic images of best quality with clearly visible filler grains.

2

Coal powder fractions distribution in thermal power plant mixture channel presented by numerical calculations

Zivkovic N., Stefanovic P., Cvetinovic D.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2008

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z. 73 [253]

311-318

EN

One of the problems during exploalation period of thermal power plant is in determine and optimize distribution of various coal powder fractions in the mixture channel. Regulation of distribution with shutters, positioned after the mills, is proposed solution. The paper present distribution of coal powder fractions, obtained by numerical calculations, using numerical software for modelling of two-phase flow problems. The problem is two-dimensional, considering that, transversal dimension of the domain is relatively big compared with the other two dimensions, and volume occupied by solid phase is much less than volume occupied by continual phase. Continual phase is treated by an Eulerian approach, and solid phase is modeled by Lagrangian approach. The model takes in consideration coupling of phases by PSI-CELL method. Turbulence was modeled with standard k-ε model. The model treats particles as an ideal sphere. In order to determine particle movement, all relevant forces, (with continual affect and impulse affect), are incorporated in the model. The results obtained, include velocity field and profiles of continual phase, concentration field and profiles of coal particles and mass flow distribution at the outlet cross section of mixture channel for various coal particle diameters and various angular positions of shutters.

3

Numerical simulation of coal powder distribution along the air-coal mixture channel influenced by various shutter angles

Zivkovic N., Stefanovic P., Zivkovic G., Cvetinovic D.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2006

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z. 68 [231]

261-268

EN

For implementation of the plasma system for mineral oil free combustion support and start-up on power plant boilers few technical problems have be to solved. One of the key requirements in the implementation process is a regulation of coal powder distibution in the mixture channel in order to achieve adequate concentration in the zone where plasma has to be introduced. Regulation of powder distribution with shutters, positioned in the vertical section of the channel after the mills and prior to plasma generators is proposed solution. The paper represents numerical simulation of this problem using numerical software for modelling of two-phase flow problems, developed in Laboratory of Thermal Engineering and Energy. The model is based on Euler-Lagrangian approach. Continual phase was treated by Euleiran and disperse phase was treated Lagrangian approach. For turbulence modelling a well known k-!!! model was used. The computation results were obtained for three combinations of shutter system positions. The input data were velocity profile of continual phase and concentration profile of disperse phase in the inlet cross section, obtained by experiments. On the basis of the presented results it can be concluded that the positions of groups of shutters has a great influence on flow and concentration field in the burner channels, therefore it should be properly adopted as an adequate regulation method.