Wyniki wyszukiwania - BazTech

1

Two–Phase Flow in Porous Bed with Chemical Reaction

Niegodajew P, Asendrych D., Drobniak S., Elsner W.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2013

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z. 101

75--76

EN

Continuous growth of CO2 emission is one of the most important threats of today’s power industry. Among the alternatives allowing to solve that problem, carbon capture and storage (CCS) technology seems to be a very promising option. With this method the flue gases are being sent through the absorber where CO2 is captured by aqueous amine solution flowing countercurrently. Both phases pass through the packed bed where most of the chemical reaction occurs due to the enlarged contact area between phases. The research performed so-far included investigations with the use of laboratory or pilot installations as well as numerical modelling by means of simplified 0D or 1D models. These methods have, however, limited capabilities as they do not allow to have an insight into the details of the process.

2

Numerical modelling of CO2 desorption process coupled with phase transformation and heat transfer in CCS installation

Niegodajew P., Asendrych D., Drobniak S.

Journal of Power Technologies

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2013

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Vol. 93, nr 5

354--361

EN

The paper concerns the research aimed at developing the computational fluid dynamics (CFD) model of amine based carbon dioxide capture process in post combustion capture (PCC) technology. Numerical model of absorber column (being the first stage of PCC cycle) including complex hydrodynamics, heat transfer and absorption reaction with the use of monoethanolamine (MEA) has already been developed and described in detail in [1, 2]. This paper focuses on the second stage of PCC cycle i.e. desorber (stripper) column. Eulerian multiphase model was adopted to resolve two-phase countercurrent gas-liquid flow in porous region with desorption reaction, multiphase heat transfer and evaporation/condensation phenomena. The preliminary calculations were performed on simplified geometry of stripper column in order to reduce the computational time required. Results have shown a physically correct behaviour, proving its relevance and its usefulness to practical applications.

3

Modelling the dynamics of flexible and rigid fibres

Kondora G., Asendrych D.

Chemical and Process Engineering

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2013

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Vol. 34, nr 1

87--100

EN

A particle-level simulation technique has been developed for modelling fibre suspension flow in a converging channel of a papermachine headbox. The fibre model is represented by a chain of elements connected together. The model was verified by the simulation of rigid fibre dynamics in a simple shear flow. The period of rotation was found to be in a very good agreement with theory and reference data. The model was then employed to simulate fibre motion in a converging channel of a papermachine headbox. Fibre suspension motion was resolved using two-step procedure. Velocity field was calculated by means of a commercial CFD code ANSYS Fluent with RSM turbulence model applied and used as an input to the in-house code allowing to simulate fibre dynamics. Results of the calculations were used to construct the fibre orientation probability distribution (FOPD) which was found to be consistent with available experimental data.

4

CFD modelling of CO2 capture in a packed bed by chemical absorption

Asendrych D., Niegodajew P., Drobniak S.

Chemical and Process Engineering

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2013

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Vol. 34, nr 2

269--282

EN

The paper deals with numerical modelling of carbon dioxide capture by amine solvent from flue gases in post-combustion technology. A complex flow system including a countercurrent two-phase flow in a porous region, chemical reaction and heat transfer is considered to resolve CO2 absorption. In order to approach the hydrodynamics of the process a two-fluid Eulerian model was applied. At the present stage of model development only the first part of the cycle, i.e. CO2 absorption was included. A series of parametric simulations has shown that carbon dioxide capture efficiency is mostly influenced by the ratio of liquid (aqueous amine solution) to gas (flue gases) mass fluxes. Good consistency of numerical results with experimental data acquired at a small-scale laboratory CO2 capture installation (at the Institute for Chemical Processing of Coal, Zabrze, Poland) has proved the reliability of the model.

5

Numerical analysis of CO2 capture efficiency in post combustion CCS technology in terms of varying flow conditions

Niegodajew P., Asendrych D., Drobniak S.

Archives of Thermodynamics

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2013

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Vol. 34, no. 4

123--136

EN

The paper deals with the computational fluid dynamics modelling of carbon dioxide capture from flue gases in the post combustion-capture method, one of the available carbon capture and storage technologies. 30% aqueous monoethanolamine solution was used as a solvent in absorption process. The complex flow system including multiphase countercurrent streams with chemical reaction and heat transfer was considered to resolve the CO2 absorption. The simulation results have shown the realistic behaviour and good consistency with experimental data. The model was employed to analyse the influence of liquid to gas ratio on CO2 capture efficiency.

6

Modelowanie przeciwprądowego przepływu gaz - ciecz w złożu porowatym

Niegodajew P., Asendrych D.

Modelowanie Inżynierskie

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2012

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T. 14, nr 45

108--115

PL

Praca dotyczy modelowania przeciwprądowego przepływu dwufazowego gaz-ciecz w kolumnie z wypełnieniem porowatym. Wielofazowy model eulerowski został wykorzystany do opisania ruchu płynu w dwu-wymiarowej, osiowosymetrycznej domenie obliczeniowej. Jako czynniki zastosowane zostały woda i powietrze. Opory przepływu fazy dominującej, tj. gazu, zostały wyznaczone na drodze eksperymentalnej. Uzyskane wyniki obliczeń wskazują na adekwatność zastosowanego modelu do analizowanego przepływu.

EN

The paper deals with the numerical modelling of countercurrent flow through the absorber column with packed bed inside. Model geometry follows the real pilot plant absorber column localized in IChPW in Zabrze. The Euler-Euler model was applied to treat the gas-liquid system in 2-dimensional and axisymmetric domain. The flow is dominated by the gas phase and the liquid creates the film on the packed bed. The results obtained have shown the realistic behaviour of the system in terms of its hydrodynamics.

7

Numerical studies on the extrusion of visco-elastic particles through slots in a screening process

Asendrych D.

Chemical and Process Engineering

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2008

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Vol. 29, z. 1

43-60

EN

The paper is devoted to the optimisation of contaminants removal from cellulose fibres suspension during paper recycling. The behaviour of viscoelastic particles (originating from adhesive tapes and labels entering recycling loops) in the screen is studied numerically upon varying key parameters of the process showing their impact on the separation efficiency.

PL

Badano optymalizację procesu usuwania zanieczyszczeń z zawiesiny włóknistej w trakcie przetwórstwa makulatury. Zachowanie lepkosprężystych cząsteczek (których źródłem są samoprzylepne taśmy i naklejki) na sicie sortownika poddano analizie numerycznej, która umożliwiła określenie wpływu parametrów procesu na jego efektywność.

8

Active flow control by countercurrent jets

Asendrych D.

Journal of Theoretical and Applied Mechanics

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2007

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Vol. 45 nr 3

463-477

EN

The paper presents the results of experimental analysis of the flowfield in slightly heated countercurrent round jets. The velocity measurements were carried out by means of hot-wire anemometry (a combined CTACCA system for temperature compensation). The instantaneous signals collected during the experiment were digitally processed and used for determination of the statistics of velocity and temperature fields including frequency characteristics. The results revealed that the fluid aspiration at the jet periphery significantly influences large-scale structures naturally existing in the flow and being responsible to a great extent for the mixing and entrainment in the free flow. The aspiration intensity was found as the key parameter deciding about the way the reverse flow either inhibits or enhance transport processes.

PL

W pracy zaprezentowano wyniki badań eksperymentalnych pola przepływu w lekko nieizotermicznych strugach przeciwbieżnych. Pomiary prędkości zostały przeprowadzone z użyciem 2-kanałowego układu termoanemometrycznego (układ stałotemperaturowy CTA z kompensacją temperatury kanałem stałoprądowym CCA). Sygnały pomiarowe zarejestrowane w trakcie eksperymentu były następnie poddane obróbce cyfrowej w celu uzyskania statystyk pól prędkości i temperatury, obejmujących również rozkłady widmowe turbulentnych fluktuacji. Uzyskane wyniki wykazały, iż zastosowanie przepływu zwrotnego na obrzeżach strugi głównej modyfikuje znacząco charakterystyki zorganizowanych struktur wirowych, występujących w przepływie w sposób naturalny i odpowiedzialnych w dużym stopniu za podsysanie czynnika z otoczenia oraz jego wymieszanie ze strugą główną. Obraz pola przepływu okazał się być silnie zależny od intensywności odsysania, która w zależności od poziomu może prowadzić do wytłumienia lub intensyfikacji procesów transportu promieniowego.

9

Modelling of fluid flow with complex rheology

Niklas M., Asendrych D.

Systems : journal of transdisciplinary systems science

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2006

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Vol. 11, nr 1

63-73

EN

The paper concerns numerical modelling of the paper pulp flow of a non-Newtonian fluid with complex rheological properties. The work is aimed at optimisation of the performance of a hydropulper used for the recovered paper defibration in paper recycling technology. The phenomenon under consideration reveals high degree of complexity and its proper modelling requires to solve a number of particular problems related to duality of flow regimes (coexistence of turbulent and laminar regimes governed by different constitutive models), complicated geometry, presence of moving elements of machine, unsteady nature of phenomena and complex material properties of medium. So high degree of complexity enforced the necessity of the use of commercial code Fluent as a computational tool. Its effective use was however possible after code extension with additional procedures (the so called UDF - the user defined functions) allowing to meet the requirements of the rheology

10

Modelling of multi-phase flow phenomena in waste paper processing technology

Asendrych D.

Turbulence : international journal

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2005

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Vol. 11

201-212

EN

The paper presents the numerical simulation of the flow field pattern in the pressure screen - a machine used for removal of undesircd contaminants during paper recycling process. The simulation is aimed at delivering the unsteady pressure distribution at the screen plate surface which will then be used as a boundary and initial conditions for the analysis of structural deformation of viscoelastic particles of contaminants.

11

Numerical simulation of microchannel network with complex geometry

Niklas M., Favre-Marinet M., Asendrych D.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2005

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Vol. 53, nr 4

351-359

EN

The paper presents the results of a numerical study devoted to the hydraulic properties of a network of parallel triangular microchannels (hydraulic diameter Dh = 110 [mi]m). Previous experimental investigations had revealed that pressure drop through the microchannels system dramatically increases for the Reynolds number exceeding value of 10. The disagreement of the experimental findings with the estimations of flow resistance based on the assumption of fully developed flow were suspected to result tram the so-called scale effect. Numerical simulations were performed by using the classical system of flow equations (continuity and Navier-Stokes equations) in order to explain the observed discrepancies. The calculations showed a very good agreement with the experimental results proving that there is no scale effect for !he rnicrochannels considered, i.e. the relevance of the constitutive flow model applied was confirmed. It was also clearly indicated that the excessive pressure losses in the high Reynolds number range are due to the secondary flows and separations appearing in several regions of the microchannel system.

12

Numerical modelling of fluid flow and heat transfer in microchannels

Favre-Marinet M., Gamrat G., Asendrych D.

Turbulence : international journal

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2004

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Vol. 10

75-75

EN

The work concerns three-dimensional numerical modelling of fluid flow and heat transfer in large-span rectangular microchannel. Channel height being the key geometrical parameter, was varied hi the range from 0.3 to 1 mm. The width of channel was equal to 250 mm what allowed to treat microchannel as a two-dimensional. The computational domain followed the details of experimental facility used in preceding research step. The numerical model assumed the laminar flow of water (506 < Re < 2023) with temperature-independent properties. The results obtained in experimental trials exhibited strong reduction of Nusselt number in comparison to theoretical law. The motivation of current simulation was to identify the reasons of discrepancies between theoretical predictions and experimental results. Among the explanations the effect of axial conduction resulting from complex geometry was supposed to have the highest significance. Main goal of current work was numerical prediction of coupling conduction-convection effect and its influence on Nusselt number values. Additionally the influence of entrance effects on the deviation of beat transfer results from the macroscale laws was taken into consideration. Comparison between experimental and numerical results was an essential part of current work and allowed to point out the weakness of some simplifications being assumed during interpretation of experimental data (i.e. uniform distribution of heat flux along fluid/solid interface turned out to be the origin of significant errors). Furthermore numerical simulations exhibited that significant part of heat resulting from conduction and insufficient insulation was delivered to water in inlet container. It could lead to false estimation of bulk temperature at channel inlet and to reduction of heat transfer effectiveness at the beginning part of microchannel. Results of current work allowed not only for verification of experimental conclusions, but also pointed out the weakness of already utilised experimental setup and were helpful in a design of a new experimental installation.

13

ERCOFTAC special interest group #38 on microfluidics and micro heat transfer : the report on the kick-off meeting

Favre-Marinet M., Steenhoven van A., Drobniak S., Asendrych D.

Turbulence : international journal

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2004

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Vol. 10

59-65

14

Niestabilność absolutna nieizotermicznej, kołowej strugi powietrza

Drobniak S., Bogusławski A., Frania T., Asendrych D.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2000

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z. 14

39-44

PL

Struga swobodna o gęstości niższej niż gęstość otoczenia charakteryzuje się bardzo silnymi, okresowymi oscylacjami parametrów przepływu. Oscylacje te, interpretowane jako wynik niestabilności absolutnej, odpowiedzialne są nie tylko za strukturę turbulencji przepływu, lecz wpływają istotnie na pole prędkości średniej czy generację hałasu. Zjawisko niestabilności absolutnej stanowi zatem nie tylko istotny problem poznawczy, lecz ma bardzo istotne znaczenie w technicznych zastosowaniach. W pracy przedstawiono wyniki pomiarów pola prędkości średniej oraz fluktuacyjnej w strudze izotermicznej oraz podgrzanej, zdominowanej obecnością niestabilności absolutnej.

EN

A free jet with density lower than the ambient fluid is subjected to very strong periodic oscillations of the flow parameters. These oscillations interpreted as a result of absolute instability are responsible for the turbulence flow structure but also influence significantly the mean velocity field and noise generation. The absolute instability can be considered as a fundamental research problem but it has also significant importance in technical applications. The paper presents measurements of mean and fluctuating velocity field in isothermal and heated jet dominated by the absolute instability.

15

Niestabilność absolutna swobodnej strugi osiowosymetrycznej

Bogusławski L., Frania T., Asendrych D.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2000

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nr 117, vol. 2

27-32

PL

Struga swobodna o gęstości niższej niż gęstość otoczenia charakteryzuje się bardzo silnymi, okresowymi oscylacjami parametrów przepływu. Oscylacje te, interpretowane jako wynik niestabilności absolutnej, odpowiedzialne są nie tylko za strukturę turbulencji przepływu, lecz wpływają istotnie na pole prędkości średniej czy generację hałasu. Zjawisko niestabilności absolutnej stanowi zatem nie tylko istotny problem poznawczy, lecz ma bardzo istotne znaczenie w technicznych zastosowaniach. W pracy przedstawiono wyniki pomiarów pola prędkości średniej oraz fluktuacyjnej w strudze izotermicznej oraz podgrzanej, zdominowanej obecnością niestabilności absolutnej.

EN

A free jet with density lower than the ambient fluid is subjected to very strong periodic oscillations of the flow parameters. These oscillations interpreted as a result of absolute instability are responsible for the turbulence flow structure but also influence significantly the mean velocity field and noise generation. The absolute instability can be considered as a fundamental research problem but it has also significant importance in technical applications. The paper presents measurements of mean and fluctuating velocity field in isothermal and heated jet dominated by the absolute instability.

16

Intensyfikacja procesów transportu w swobodnych strugach przeciwbieżnych

Asendrych D.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2000

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nr 117, vol. 2

15-20

PL

Praca zawiera wyniki eksperymentalnej analizy pola prędkości w osiowosymetrycznych przeciwprądowych strugach powietrznych. Badaniom poddano wpływ intensywności odsysania czynnika na charakter pola prędkości na osi przepływu. Stwierdzono, iż zastosowanie zewnętrznej strugi koncentrycznej prowadzi do znacznych modyfikacji pola przepływu, a w szczególności do wzrostu intensywności fluktuacji prędkości. Uzyskane wyniki świadczą o możliwości wykorzystania strug przeciwbieżnych do intensyfikacji procesów transportu i zastosowania ich w różnych typach przepływów technicznych.

EN

The paper contains the results of experimental analysis of the velocity field in round countercurrent air jets. The influence of aspiration intensity on the velocity characteristics on the jet centreline was studied. The research revealed significant modifications of the flowfield in the presence of annular reverse flow in particular great increase of turbulence intensity level. The results obtained suggest that the countercurrent jets could for utilised to the improvement of transport processes in a number of practical flow situations.

17

An improved method for spectral estimation of LDA discrete signals

Asendrych D., Drobniak S.

Metrologia i Systemy Pomiarowe

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1999

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T. 6, z. 1-2

11-26

EN

The paper presents the method for reducing spectral variability of the estimates obtained by slotted correlation algorithm applied to discrete signals of LDA processors. Twomodifications were considered and the proporsal of the so-called variable tolerance range turned to yield the improvementof the spectral estimation accuracy. The computiational time as well as integrated spectral ambiguity (which is a measure of accuracy of calculations) have been carefully studied. Simple rules governing the above parametres have been proposed in the paper. It was also shown that the signal acquisition carried out in the Fixed N f running mode (anailable in the most of the commercial LDA counter analysers ) may contarminate spectral estimates with the increased level of the wide-band noise.

PL

W pracy przedstawiono metodę redukcji obciążenia estymat widmowych uzyskiwanych w wyniku przetwarzania sygnałów wyjściowych anometrów laserowych (LDA) z procesorem typu counter przy użyciu algorytmu slotted correlation. Zaproponowano dwie modyfikacje oryginalnej procedury obliczeniowej, z których jedna, tj. metoda zmiennego przedziału tolerancji okazała się prowadzić do polepszenia dokładności obliczeń. Szczegółowa analiza własności algorytmu pozwoliła określić prostą regółę wiążącą ze sobą miary dokładności obliczeń na czas obliczeniowy. Wykazano również, iż rejestracja sygnałów przy użyciu jednego z modów pracy procesora LDA (dostępnego w większośći komercyjnych systemów) prowadzi do zwiększonego poziomu szumów spektralnych wyznaczanych estymat widmowych.