Wyniki wyszukiwania - BazTech

1

Modelling and experimental investigation of waste tyre pyrolysis process in a laboratory reactor

Rudniak L., Machniewski P.M.

Chemical and Process Engineering

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2017

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Vol. 38, nr 3

445--454

EN

A mathematical model of waste tyre pyrolysis process is developed in this work. Tyre material decomposition based on a simplified reaction mechanism leads to main product lumps: noncondensable (gas), condensable (pyrolytic oil) and solid (char). The model takes into account kinetics of heat and mass transfer in the grain of the shredded rubber material as well as surrounding gas phase. The main reaction routes were modelled as the pseudo-first order reactions with a rate constant calculated from the Arrhenius type equation using literature values of activation energy determined for main tyre constituents based on TG/DTG measurements and tuned pre-exponential parameter values obtained by fitting theoretical predictions to the experimental results obtained in our laboratory reactor. The model was implemented within the CFD software (ANSYS Fluent). The results of numerical simulation of the pyrolysis process revealed non-uniformity of sample’s porosity and temperature. The simulation predictions were in satisfactory agreement with the experimentally measured mass loss of the tyre sample during pyrolysis process investigated in a laboratory reactor.

2

Modelling and measurement of bubble formation and growth in electroflotation processes

Sarkar S. K., Machniewski P.M., Evans G.M.

Chemical and Process Engineering

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2013

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Vol. 34, nr 3

327--336

EN

Electroflotation is used in the water treatment industry for the recovery of suspended particles. In this study the bubble formation and release of hydrogen bubbles generated electrolytically from a platinum cathode was investigated. Previously, it was found that both the growth rate and detachment diameter increased with increasing wire diameter. Conversely, current density had little effect on the released bubble size. It was also found that the detached bubbles rapidly increased in volume as they rose through the liquid as a result of decreasing hydrostatic pressure and high levels of dissolved hydrogen gas in the surrounding liquid. The experimental system was computationally modelled using a Lagrangian-Eulerian Discrete Particle approach. It was revealed that desorption of gaseous solutes from the electrolyte solution, other than hydrogen, may have a significant impact on the diameter variation of the formed bubbles. The simulation confirmed that liquid circulation, either forced or induced by the rising bubble plume, influences both the hydrogen supersaturation (concentration) in the neighbourhood of the electrode and the size of the resulting bubbles.

3

Modelling of bubble formation with the aid of CFD

Biń A. K., Machniewski P. M., Rudniak L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2004

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Vol. 8, No 1

17-26

EN

Results of a numerical simulation of the bubble formation process obtained with the aid of computational fluid dynamics (CFD) approach are presented. A solution of the momentum balance (Navier-Stokes) equations was coupled with the volume of fluid (VOF) algorithm for tracking the gas-liquid interface in 2D and 3D domains. The simulation results are compared with the experimental data regarding the influence of gas flow rate on the bubble formation regime and volume of the produced bubbles in a low-viscosity system (air-water). As the simulation results are in agreement with the experimental observations, the VOF algorithm is found to be a valuable tool for studying the phenomena of gas-liquid interaction.

4

Hydrodynamika obrotowego dystrybutora gazu w warunkach przepływu poprzecznego

Biń A., Machniewski P.M., Rudniak L., Evans G.M.

Inżynieria Chemiczna i Procesowa

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2004

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T. 25, z. 3/1

709-714

PL

W pracy przedstawiono wyniki symulacji CFO wirującego walcowego dystrybutora gazu w pionowym kanale, w warunkach przepływu jednofazowego oraz w dwufazowego z uwzględnieniem kawerny gazowej utworzonej pod dystrybutorem. Przedstawiono wyniki pomiarów pola prędkości uzyskane techniką anemometrii obrazowej (PIV), które porównano z wynikami obliczeń.

EN

The results of CFD simulation of a rotating cylindrical gas sparger in a downflowing liquid are presented. The simulations cover one-phase flow (73% aqueous glycerol) and two-phase flow (air-water) with special care taken to modelling the gas cavity that forms under such conditions. The velocity field measured with the aid of Particle Image Velocimetry (PIV) is compared with the simulation results for the case of one-phase flow.

5

Hydrodynamics of large attached bubbles in a downward liquid flow

Evans G.M., Biń A. K., Machniewski P.M.

Inżynieria Chemiczna i Procesowa

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2000

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T. 21, z. 1

199-217

EN

Stationary gas slug attached to the gas sparger in the downcomer of an air-lift fermenter can cause serious operational problems. The results of experimental investigation on the influence of liquid. and gas flow rates on the behavior of an attached bubble formed in a vertical pipe have been presented. The size distribution of the bubbles shed from the gas slug base in the mixing zone has also been measured and correlated with the mean energy dissipation rate in the zone.

PL

Stacjonarne korki gazowe tworzące się pod dystrybutorem gazu w pionowych rurach (downcomer) bioreaktorów typu air-lift są niepożądanym zjawiskiem utrudniającym pracę tych urządzeń. Przedstawiono wyniki pomiarów wpływu prędkości cieczy oraz gazu (zasilania) na zachowanie się korków gazowych w pionowej rurze z centralnie umieszczonym dystrybutorem gazu. Zmierzono także rozkład średnic małych pęcherzy odrywanych w strefie intensywnego mieszania, które skorelowano ze średnią szybkością dyssypacji energii w tej strefie.