Wyniki wyszukiwania - BazTech

1

CFD simulations as a support of experimental research in a rapid compression expansion machine facility

Jach A., Pyszczek R., Kapusta Ł. J., Teodorczyk A.

Journal of KONES

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2018

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Vol. 25, No. 4

141--147

EN

The main aim of this study to reproduce methane combustion experiment conducted in a rapid compressionexpansion machine using AVL FIRETM software in order to shed more light on the in-cylinder processes. The piston movement profile, initial and boundary conditions as well as the geometry of the combustion chamber with a prechamber were the same as in the experiment. Authors by means of numerical simulations attempted to reproduce pressure profile from the experiment. As the first step, dead volume was tuned to match pressures for a non-combustion (air-only) case. Obtained pressure profile in air compression simulations was slightly wider (prolonged occurrence of high pressure) than in the experiment, what at this stage was assumed to have negligible significance. The next step after adjusting dead volume included combustion simulations. In the real test facility, the process of filling the combustion chamber with air-fuel mixture takes 15 s. In order to shorten computational time first combustion simulations were started after the chamber is already filled assuming uniform mixture. These simulations resulted in more than two times higher maximum pressure than recorded in experiments. It was concluded that turbulence decays quickly after filling process, what was also confirmed by next combustion simulations preceded by the filling process. Then the maximum pressure was significantly decreased but still it was higher than in the experiments. Based on the obtained results it was assumed that the discrepancy noticed in air cases is further increased when combustion is included. Moreover, the obtained results indicated that pre-combustion turbulence level is very low and suggested that either piston profile movement is not correct or there is high-pressure leak in the test facility.

2

Evaluation of the possibilities of adapting a constant volume combustion chamber for research on ignition of hypergolic propellants under low and high-pressure conditions

Krzesicki M., Boruc Ł., Kapusta Ł. J.

Combustion Engines

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2018

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R. 57, nr 2

9--13

EN

In this study, the adaptation possibilities of a constant volume combustion chamber (CVCC) for research on the ignition of hypergolic propellants are presented. The application of hypergolic bipropellants and crucial parameters regarding their ignition behaviour are discussed. The initial studies on ignition delay measurements presented here does not cover the whole range of conditions present in practical systems where hypergolic ignition occurs. In the study, a need for an evaluation of the influence of pressure on the ignition delay was indicated as the reason to conduct research on hypergolic ignition in low and high-pressure environments. Moreover, the study reviews the state-of-the-art experimental methods of investigating the ignition under atmospheric, low and high-pressure conditions, including those utilizing a constant volume combustion chamber. The drop test was pointed out as the most commonly used method; this makes it advantageous in terms of comparing the results with those obtained by other researchers. Therefore, the drop test was selected as a method to be used in a CVCC. The test rig developed here was designed based on a CVCC initially designed for diesel sprays’ visualization in high-pressure conditions. All the required modifications, especially the design of the oxidizer dosing unit, are presented in the study.

3

Numerical simulations of n-heptane spray in high pressure and temperature environments

Smuga W., Kapusta Ł. J., Teodorczyk A.

Journal of Power Technologies

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2017

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Vol. 97, nr 1

1--6

EN

In this study n-heptane spray in supercritical environments was simulated using commercial CFD (Computational Fluid Dynamic) software AVL Fire. The numerical results were analyzed in terms of global spray parameter, and spray penetration. The results obtained were compared with experimental data available at Sandia National Laboratories. N-heptane spray simulations were performed in the same conditions as in the Sandia experiments. The goal of the study was to assess whether the Lagrangian approach performs well in engine relevant conditions in terms of spray global parameters. Not included in this assessment was the influence of supercritical mixing on liquid-gas interphase. The major element was the potential for practical application of the commercial CFD code in terms of properly representing global spray parameters and thus mixture formation in supercritical conditions, which is one of the core aspects in whole engine process simulation. The key part of the study was mesh optimization. Therefore, the influence of mesh density on both the accuracy of calculations and the calculation time was determined, taking into consideration detailed experimental data as initial conditions for the subsequent calculations. This served as a basis to select the optimal mesh with regard to both accuracy of the results obtained and time duration of the calculations. As a determinant of accuracy, the difference within a range of evaporated fuel stream was used. Using selected mesh the set of numerical calculations were performed and the results were compared with experimental ones taken from the literature. Several spray parameters were compared: spray tip penetration, temperature of the gaseous phase and mixture fraction in the gaseous phase. The numerical results were very consistent in respect of spray tip penetration. The other parameters were influenced by specific features of the Lagrangian approach. Nevertheless the results obtained showed that the Lagrangian approach may be used for engine relevant conditions.

4

LES numerical study on in–injector cavitating flow

Pyszczek R., Kapusta Ł. J., Teodorczyk A.

Journal of Power Technologies

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2017

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Vol. 97, nr 1

52--60

EN

In this paper a computational study on hexane flow in a fuel injector is presented. Large Eddy Simulation (LES) was used to capture the turbulent patterns present in the flow. The main aim was to investigate the cavitation phenomenon and its interaction with turbulence as well as the influence of injection pressure and backpressure on fuel mass flow and flow conditions. Analysis of the approach to define the outlet boundary conditions in terms of convergence time and fluid mass outflow oscillations formed a crucial part of the study. Numerical simulations were performed with AVL Fire CFD (Computational Fluid Dynamics) software. The Euler-Euler approach and multifluid model for multiphase flow modelling were applied. Injector needle movement was included in the simulation. Results show that the additional volumes attached to the nozzle outlets improved the convergence of the simulations and reduced mass outflow oscillations. Fuel mass flow at the outlets was dependent on inlet pressure, position of the needle and backpressure, while the influence of backpressure on fuel mass flow was negligible. The presence of the vapor phase at the exit of the nozzles did not affect average fuel mass flow. All the simulations showed interaction between the gaseous phase distribution and the turbulence of the flow.

5

The influence of the injection frequency on the urea selective catalytic reduction systems performance

Rogóż R., Jaworski P., Kapusta Ł. J., Teodorczyk A.

Combustion Engines

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2017

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R. 56, nr 3

73--77

EN

This study presents the influence of the UWS injection frequency on a close coupled SCR systems performance. The investigation was performed with the CFD tool AVL Fire. In the paper the analysis of four different UWS injection frequencies in the three different operating points of diesel engine was shown. The assessments of the system performance was referred to the ammonia distribution at catalyst intake and wall film formation inside the investigated geometry, as these are considered as crucial in such a configuration. The results showed that injection frequency affects both factors on different level depending from the flow conditions. In addition, the wall film crystallization risk was discussed basing on the obtained wall film characteristics.

6

Analysis of the microstructure of the fuel spray atomized by marine injector

Lewińska J., Kapusta Ł. J.

Combustion Engines

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2017

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R. 56, nr 2

120--124

EN

The process of the atomization and formation of the fuel spray can be described by macro- and microstructure parameters. Knowledge of these parameters may be a key information to conduct further optimization of the combustion process. This paper presents the research results of the microstructure parameters of the diesel oil spray atomized with marine engine injector. A measurement technique, named Laser Induced Fluorescence (LIF) in the combination with Mie scattering was used to determine LIF/Mie ratio across the spray. The fuel was injected into a constant volume vessel. LIF and Mie signals were recorded by two cameras at the same time. Nd:YAG pulsed laser was used to create light sheet for spray illumination. Wavelength of λ = 266 nm was used in this study.

7

SCR systems for NOx reduction in heavy and light duty vehicles

Jaworski P., Jarosiński S., Cortes Capetillo A., Kapusta Ł. J., Ziółkowski A., Grzywnowicz R.

Combustion Engines

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2016

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R. 55, nr 1

32--36

EN

Air pollution has become an important worldwide problem. The European Commission credits road and water transport as the major source of NOx pollution, and of being responsible for around 50% of the total air pollution in urban areas. During the last decade, the use of SCR technologies have gained popularity as a method for NOx reduction, the technology is widely considered as one of the solutions for road transport emissions. This paper presents a review of the different SCR system designs derived from the various factors and regulations in the automotive industry which have influenced the technology, along with a parametric study of a proprietary SCR system for heavy duty application.

8

Numerical study on in-cylinder blending by means of a simultaneous direct injection of two liquid fuels in a heavy duty compression ignition engine

Kapusta Ł. J., Teodorczyk A.

Transactions of the Institute of Fluid-Flow Machinery

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2015

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nr 128

5--18

EN

Dual fuel combustion has been recently of high interest, mainly in terms of utilization of fuels different than diesel fuel in compression ignition engines. Depending on the properties of a fuel which is additional to diesel fuel, and the type of the additional fuel supply method the combustion process may be strongly modified comparing to single fuel combustion. Nowadays the modification of the combustion process becomes the reason for implementing the dual fuelling process. However, still the main reason for its implementation remains the utilization of nonconventional fuels in compression ignition engines. Among different types of dual fuel systems the one based on simultaneous direct injection of two fuels seems to be most flexible one. It allows to stratify the charge in the cylinder, blend two different fuels at any ratio and does not decrease volumetric efficiency. Therefore, this study aims at mixture formation in a heavy duty engine employing simultaneous direct injection of two different liquid fuels. Special attention was paid to spray breakup and simultaneous evaporation of two fuels which are the key processes in mixture formation.

9

SCR systems for NOx reduction in heavy duty vehicles

Jaworski P., Kapusta Ł. J., Jarosiński S., Ziółkowski A., Cortes Capetillo A., Grzywnowicz R.

Journal of KONES

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2015

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Vol. 22, No. 4

139--146

EN

Air pollution has become an important worldwide problem. The European Commission credits road and water transport as the major source of NOx pollution, and of being responsible for around 50% of the total air pollution in urban areas. In Poland, around 45% of the country NOx emissions are attributed to transportation. During the last decade, the use of SCR technologies have gained popularity as a method for NOx reduction, the technology is widely considered as one of the solutions for road transport emissions. SCR technology had previously been employed in stationary plants, maritime transportation and other installations using combustion processes in which exhaust conditions are easier to control. The advance on the technology led to the introduction of the first heavy-duty vehicle with an SCR system into the market in 2004. New technologies and applications are constantly appearing, for example, SCR exhaust gas cleaning systems for reciprocating engines are still under development and compression ignition engines can be found in a number of different applications. The technology still needs to be studied and improved as constant problems and knowledge is required in issues such as urea injection, crystallization and NOx reduction efficiency. Moreover, the designs intended for heavy duty vehicles need to meet vehicle limitations and EURO emissions restrictions. This paper presents a review of the different SCR system designs derived from the various factors and regulations in the automotive industry, which have influenced the technology, along with a parametric study of a proprietary SCR system for heavy-duty application.

10

Laser based diagnostic system for spray measurements

Kapusta Ł. J., Jaworski P., Teodorczyk A., Kowalski J.

Journal of KONES

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2015

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Vol. 22, No. 3

91--98

EN

The paper discusses the capabilities of the laser diagnostic system for dispersed multiphase flows measurements, which was recently commissioned at the Institute of Heat Engineering (ITC) at Warsaw University of Technology. The system presented in the paper is multifunctional and is capable to use different measurements techniques such as shadowgraphy, Mie scattering (scattering on the gas-liquid interface) and LIF (laser induced fluorescence). It provides possibility of switching from one technique to another depending on the characteristics of the observed combustion/injection mixing process. The operational features are discussed in-detail. The study presents the required and possible system setups. Special attention was focused on the system components, which are needed for relevant measurement techniques. Moreover, the limitations of the measurement techniques are discussed and the example measurements are presented. The study shows that using different techniques extends the measurement capabilities of the system with minimum investment costs. This results from the fact that certain system components for different techniques are the same. Moreover, one can conclude that the system design allows certain measurement methods to be applied simultaneously, which results in synergy by making possible drawing more advanced conclusions on observed phenomena

11

Jet and droplet breakup modelling approaches

Kapusta Ł. J., Jaworski P., Kowalski J.

Journal of KONES

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2015

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Vol. 22, No. 3

83--90

EN

Three-dimensional computational fluid dynamics (CFD) plays important role in engines development. The mixture formation in a direct-injection piston engines poses a huge challenge in successful simulations of the engine processes. It is due to the fact that the spray as a two-phase flow complicates the computational process. Moreover, this multiphase flow is not uniform. Three main zones, depending on the distance from the nozzle exit are visible when a liquid is injected. Very dense so called “thick” in a direct vicinity of the injector hole, than “thin” as a result of pri-mary breakup downstream the injector and finally in the certain distance from the injector appears “very thin” region as a result of secondary breakup. It is important to take into account that the liquid phase in various regimes behaves differently and is under influence of different phenomena. The modelling approach needs to take in to consideration all those elements. This paper focuses on presentation of the theory and numerical models for primary and secondary breakup phenomena. The primary breakup is a process that results from a combination of three mechanisms: turbu-lence within liquid phase, implosion of cavitation’s bubbles and aerodynamic forces acting on a liquid jet. Secondary breakup regime occurs mainly due to the aerodynamic interactions between the liquid and the gaseous phase.

12

Numerical simulations of dual fuel combustion in a heavy duty compression ignition engine

Kapusta Ł. J., Teodorczyk A.

Combustion Engines

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2015

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R. 54, nr 4

47--56

EN

In this study dual fuel direct injection was studied in terms of utilizing in compression ignition engines gaseous fuels with high octane number which are stored in liquid form, specifically liquid propane. Due to the fact that propane is not as much knock-resistant as natural gas, instead of conventional dual fuel system a system based on simultaneous direct injection of two fuel was selected as the most promissing one. Dual fuel operation was compared with pure diesel operation. The performed simulations showed huge potential of dual fuel system for burning light hydrocarbons in heavy duty compression ignition engines. However, further secondary fuel injection system optimization is required in order to improve atomization and lower the emissions.

PL

W niniejszej pracy przeanalizowano dwupaliwowy układ zasilania oparty na bezpośrednim wtrysku dwóch paliw w kontekście wykorzystania gazowych paliw o dużej liczbie oktanowej, mianowicie propanu, w silnikach o zapłonie samoczynnym. Z uwagi na to, iż propan nie jest tak odporny na spalanie stukowe jak metan, zamiast konwencjonalnego układu dwupaliwowego łączącego wtrysk bezpośredni i pośredni zdecydowano się na zastosowanie koncepcji zasilania opartej na bezpośrednim wtrysku dwóch paliw. Praca silnika w trybie dwupaliwowym została porównana z pracą silnika wyłącznie na oleju napędowym. Przeprowadzone symulacje pokazały duży potencjał układów dwupaliwowych w kontekście wykorzystania lekkich węglowodorów w silnikach o zapłonie samoczynnym dużej mocy. Jednak, dalsza optymalizacja układu paliwowego jest niezbędna, aby poprawić proces rozpylenia paliwa i obniżyć emisję.

13

LES numerical study on n-hexane injection in a compression ignition engine

Kercheva B., Kapusta Ł. J., Teodorczyk A.

Archivum Combustionis

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2014

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Vol. 34 nr 2

155--167

EN

The aim of the study was the comparison of different approaches to modeling the injection process in a heavy duty compression ignition engine. The conducted numerical investigation concerned n-hexane direct injection into the engine combustion chamber. Simulations were performed using AVL Fire software, a CFD (Computational Fluid Dynamics) code based on the control volume method. In order to achieve engine conditions, computational model was built basing on piston and cylinder geometry of a real engine and the mesh deformation was defined according to crank mechanism dimensions of the engine. In presented simulations for modeling dispersed phase the Lagrangian approach was used. For capturing the turbulent patterns present in the flow, the Large Eddy Simulation (LES) approach was used. Three different nozzle outflow conditions were compared. In the simplest case, constant flow rate was defined. In the second one, linear stage of increase and decrease of flow rate was defined, and in the third one – the most advanced – data collected during previously done in-injector cavitating flow simulations were used to define the flow parameters on the nozzle outlet. Calculated results for all cases were analyzed and compared. The focus was on the initial stage of the spray. The results show that the way of defining parameters at the outlet influences not only the initial stage of the spray but the whole process.

14

Symulacje numeryczne przepływu heksanu przez wtryskiwacz

Kapusta Ł. J.

Zeszyty Naukowe Wyższej Szkoły Informatyki

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2012

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Vol. 11, Nr 1

71-84

PL

W pracy zostały przedstawione wyniki symulacji komputerowych przepływu heksanu przez wtryskiwacz przy maksymalnym wzniosie iglicy. Symulacje wykonano przy użyciu programu AVL Fire. Heksan dostarczany był pod ciśnieniem 30 MPa, natomiast ciśnienie na wylocie z dyszy wtryskiwacza wynosiło 12 MPa. W modelu numerycznym nie uwzględniono wymiany ciepła pomiędzy wtryskiwaczem a przepływającym płynem. Symulacje zostały przeprowadzone w stanie ustalonym celem zlokalizowania miejsc potencjalnej kawitacji oraz określenia maksymalnego wydatku przepływającego przez wtryskiwacz płynu. Symulacje przeprowadzono dla dwóch różnych średnic dysz, 0,4 mm oraz 0,6 5mm

EN

Numerical simulations of a hexane flow through the injector with fully lifted needle are described in the paper. Presented simulations were done using the AVL Fire software. Hexane was supplied to the injector under the pressure of 30 MPa. Pressure at the outlets was of 12 MPa. Heat transfer between fluid and injector walls wasn’t taken into account. Presented simulations were performed under steady steady-state conditions. The main object of the simulation was to calculate the mass flow and find the area where the pressure reaches lowest value to check if there is a threat of cavitation. Simulations were conducted for two injectors, one equipped with nozzles of diameter 0.4mm and the second one equipped with nozzles of diameter 0.65mm.

15

Metodologia szkolenia w zakresie symulacji procesów wymiany ładunku, wtrysku oraz spalania z wykorzystaniem pakietu AVL FIRE

Ćwikowski P., Kapusta Ł. J., Teodorczyk A.

Zeszyty Naukowe Wyższej Szkoły Informatyki

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2012

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Vol. 11, Nr 1

62-70

PL

W artykule zostały przedstawione doświadczenia oraz metodologia prowadzenia projektu szkoleniowego w zakresie symulacji numerycznych procesów przepływowych z wtryskiem paliwa ciekłego i spalaniem w silnikach tłokowych. Projekt noszący tytuł „Popularyzacja osiągnięć nauki polskiej i światowej w zakresie przyszłościowych trendów w procesach spalania w silnikach” składa się z dwóch części, wykładowej oraz ćwiczeniowej. Z uwagi na fakt, iż część ćwiczeniowa dotyczy zagadnień symulacji numerycznych przepływów ze spalaniem przy użyciu komercyjnego kodu CFD o nazwie AVL FIRE, w artykule skupiono się na tej części. Przedstawiono zakres oraz sposób doboru materiału dydaktycznego, z którym zapoznają się uczestnicy projektu. Oprócz tego zostały opisane rezultaty szkolenia w postaci przyrostu wiedzy uczestników szkolenia w zakresie zagadnień symulacji numerycznych.

EN

In this paper we present an overview of the experience and methodology in training project about numerical simulations of liquid fuel injection and combustion processes in piston IC engines. A project called "Popularization of polish and worlds science achievements in the field of future trends in combustion processes in piston IC engines" is composed of two parts, lectures and practical trainings. Second part is concerning in numerical simulations of flows and combustions with use of commercial CFD code as AVL Fire. Range and the way of choice of the didactic material is presented, besides results and achievements by the participants are discussed.

16

Numerical Simulations of a Simultaneous Direct Injection of Liquid And Gaseous Fuels Into a Constant Volume Chamber

Kapusta Ł. J., Teodorczyk A.

Journal of Power Technologies

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2012

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Vol. 92, nr 1

12-19

EN

Numerical simulations of the dual fuelling process by simultaneous direct injection of liquid and gaseous fuels into a combustion chamber were performed. Diesel fuel and CH4 were injected into a constant volume vessel through separate nozzles. Injection started for both fuels at the same time. The presented simulations were done using the AVL Fire code - the CFD software dedicated to engine simulations. This work was the first step in a process of modeling the full engine cycle, including combustion. The aim of the study was to validate the spray model before applying it to more complex simulations. One major simplification was made to speed up the calculation process: instead of full chamber geometry only a 60 deg sector of the cylindrical chamber containing only two nozzles, one for gaseous fuel and one for liquid was investigated. The simulation results were compared with literature data [12]. The images from the numerical solution presenting spray droplets and CH4 concentration were compared with images made by the shadowgraph technique [12].

17

Liquid Biofuels - promising energy source for a small scale power plants

Kapusta Ł. J., Sundell J.-P., Teodorczyk A.

Silniki Spalinowe

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2011

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R. 50, nr 3

EN

Basing on many years of experience in fuelling large stationary engines with palm oil Wärtsilä has started investigation into using other types of liquid biofuels (LBF) as an engine fuel for power generation. As a part of this investigation many engine tests using rapeseed oil, soybean oil, and animal fat were done. The tests described in this paper were done in parallel at two different locations. The first one was the research power plant located in Pieksämäki and the other one was the laboratory at VTT (Technical Research Centre of Finland). During the tests selected data required for evaluation whether the engine can handle investigated fuels and whether the emissions meet strict requirements have been collected analyzed and presented in this paper. Two different types of engines were used for investigation. The Wärtsilä 6L20 was used in Pieksämäki and the 4R32LN at VTT. Engines were run at different load but as for the engines for power generation the most important were parameters at full load. Therefore the study was focused on emissions at full load. As a reference the results from the LFO test were used. Results for selected fuels were compared with the reference test results. Following this comparison conclusions concerning each fuel were made.

PL

W oparciu o wieloletnie doświadczenia z wykorzystaniem oleju palmowego jako paliwa do dużych stacjonarnych silników tłokowych firma Wärtsilä rozpoczęła badania dotyczące możliwości użycia innych ciekłych bio-paliw jako paliwa do silników przeznaczonych do małych elektrowni. Częścią tych badań były testy silnikowe z wykorzystaniem oleju rzepakowego, sojowego, oraz tłuszczu zwierzęcego. Badania opisane w tym artykule zostały przeprowadzone równolegle w dwóch różnych miejscach, w laboratorium VTT (Fińskie Techniczne Centrum Badawcze). Podczas badań wybrane parametry niezbędne do oszacowania czy silnik dobrze znosi badane paliwo i czy emisje spełniają przepisy, zostały zebrane, przeanalizowane i przedstawione w artykule. Do badań wykorzystano dwa różne silniki, silnik 6L20 w Pieksämäki oraz silnik 4R32LN w VTT. Silniki pracowały pod różnym obciążeniem, jednak głównie skupiono się na parametrach przy pełnym obciążeniu. Jako odniesienie przeprowadzony został test z użyciem oleju napędowego. Wyniki dla wybranych paliw zostały porównane z testem referencyjnym. Opierając się na tym porównaniu zostały wyciągnięte i przedstawione wnioski.

18

Symulacje numeryczne spalania n-heptanu w komorze o stałej objętości

Kapusta Ł. J., Teodorczyk A., Drabik M.

Archiwum Spalania

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2011

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Vol. 11, nr 1-2

89-101

PL

W pracy zostały przedstawione wyniki symulacji komputerowych spalania n-heptanu w komorze o stałej objętości. Komora o kształcie sferycznym miała średnicę 100 mm. Do symulacji zostało wykorzystane oprogramowanie Fire firmy AVL. W rozpatrywanych przypadkach paliwo przed zapłonem było wymieszane z powietrzem. Wskaźnik stechiometrii mieszanki palnej (zdefiniowany jako odwrotność współczynnika nadmiaru powietrza) wynosił 0,8; 1 i 1,2. Temperatura początkowa mieszanki palnej we wszystkich przypadkach wynosiła 373 K natomiast wartości ciśnienia początkowego wyniosły 1 MPa oraz 2,5 MPa. Analizowanymi parametrami procesu spalania były głównie: temperatura, oraz propagacja płomienia. Uzyskane wyniki porównano z literaturowymi wynikami eksperymentalnymi przeprowadzonymi dla takich samych warunków początkowych.

EN

The paper presents the results of a numerical simulations of n-heptane combustion process in a constant volume vessel. Spherically shaped vessel had diameter of 100 mm. Simulations were done using AVL Fire software. In all investigated cases fuel was homogenized with air. Equivalence ratio of a flammable mixture was of 0.8, 1 and 1.2. The initial temperature of the mixture was in all investigated cases of 373 K. The initial pressure was of l MPa and 2.5 MPa. The analyzed parameters were mainly temperature and flame propagation. Numerical results were compared with literature data obtained for the same initial conditions