Wyniki wyszukiwania - BazTech

1

A review of technical solutions for RCCI engines

Szamrej Grzegorz, Karczewski Mirosław, Chojnowski Janusz

Combustion Engines

|

2022

|

R. 61, nr 2

36--46

EN

Engines working in dual-fuel mode need special conditions to ignite air-fuel mixture without spark plug in a good moment with high combustion efficiency. To create homogenous air-fuel mixture the conditions in the cylinder are even more demanding. Many concepts of ignition was developed, but the most effective needs perfect mixing of fuel and air, which is a serious technical challenge. Technical solutions for dual-fuel engines cover the complexity of these problems thus leading to the further development of ignition systems in internal combustion engines. Fuel supply systems, the operation strategy of them, the shape of the combustion chamber are the most important elements to change and develop for correct operation of dual-fuel engines. The literature analysis showed a small amount of research carried out to optimize the operation of dual-fuel engines The variety of engines in which a dual-fuel system can be used requires much more research about them, and solutions necessary for their correctly operation.

2

Silniki o zapłonie samoczynnym mieszanki homogenicznej kluczem do dalszego rozwoju tłokowych silników spalinowych

Szamrej Grzegorz

Biuletyn Wojskowej Akademii Technicznej

|

2021

|

Vol. 70, nr 4

15--58

PL

W artykule przedstawiono syntetycznie sposoby zapłonu mieszanki paliwowo-powietrznej w silnikach spalinowych wraz z charakterystyką ich kluczowych wad oraz zalet, problematyką ich stosowania oraz możliwością rozwoju. Dalszy rozwój tłokowych silników będzie wymagał drastycznego ograniczenia emisji szkodliwych składników spalin oraz dwutlenku węgla będącego najistotniejszym gazem cieplarnianym emitowanym przez silniki spalinowe. Z tego powodu zmianom muszą ulec nie tylko same silniki spalinowe, lecz także przede wszystkim stosowane paliwa. Aby były najskuteczniejsze, powinno się wykorzystywać samozapłon homogenicznej mieszanki paliwowo-powietrznej, co przy dzisiejszym stanie rozwoju technicznego nie jest możliwe w sposób pozwalający na realizację najbardziej zaawansowanych sposobów samozapłonu. W literaturze zagranicznej można znaleźć wiele publikacji dotyczących różnych sposobów zapłonu samoczynnego (ZS) w silnikach spalinowych, w tym zapłonu samoczynnego w silnikach dwupaliwowych. W literaturze krajowej nie ma jednak na ten temat wielu pozycji i choć można znaleźć prace dotyczące zapłonu samoczynnego w silnikach jednopaliwowych [1-10], to temat dwupaliwowego zasilania silników o ZS nie jest zbyt obszernie opisany. Z tego powodu godne uwagi wydaje się opublikowanie artykułu poruszającego ten istotny dziś temat.

EN

The article presents synthetically the methods of ignition of the air-fuel mixture in Internal Com-bustion (IC) engines along with the characteristics of their advantages and disadvantages, the problems of their use and the possibility of development. The further development of piston engines will require a drastic reduction in the emission of harmful exhaust components and carbon dioxide, which is the most important greenhouse gas emitted by IC engines. For this reason, not only the engines themselves must be changed but fuels as well. For the most effective use of them, self-ignition of a homogeneous fuel-air mixture should be implemented. In the present state of technical development is not possible to widespread use the most ad-vanced ways of self-ignition methods. Typical homogeneous charge compression ignition (HCCI), where an engine uses only one type of the fuel and correctly self-ignite in the full scope of work is still not implemented in a serial production. In the foreign literature, there is a significant number of publications on various methods of Compression Igni-tion (CI) in IC engines, including IC in Dual Fuel (DF) engines. The Polish literature, however, is extremely sparse in this matter, and one can find a number of works on CI in single-fuel engines [1-10], but the topic of DF fueling is not too extensively described. For this reason, it seems important to publish an article on this important topic today

3

Hydrocarbon species in SI and HCCI engine using winter grade commercial gasoline

Elghawi Usama, Mayouf Ahmed, Tsolakis Athanasios

Combustion Engines

|

2020

|

R. 59, nr 1

17--24

EN

The study provides a qualitative and quantitative analysis of the C5-C11 hydrocarbon species generated in Spark Ignition - Homogeneous Charge Compression Ignition (SI/HCCI) gasoline direct injection (GDI) engine at range of operating conditions. The presented results and data were obtained from the combustion of winter grade commercial gasoline containing 2% w/w ethanol (C2H5OH) for the engine operated in steady-state, fully warmed-up condition. The hydrocarbon analysis in exhaust gases was executed on a Gas Chromatography-Mass Spectrometer (GC-MS) apparatus directly connected to the engine exhaust via heated line. The highest concentration of the total hydrocarbon emissions was obtained under low load HCCI engine operation at stoichiometric fuel-air ratio. The major hydrocarbon compounds detected in the collected samples were benzene, toluene, p-xylene, and naphthalene. Benzene originates from the incomplete combustion of toluene and other alkylbenzenes which are of considerable environmental interest. During the SI engine operation, increase of the engine speed and load resulted in the increase of benzene and the total olefinic species with simultaneous decrease in isopentane and isooctane. The same trends are seen with the engine operating under HCCI mode, but since the combustion temperature is always lower than SI mode under the same engine conditions, the oxidation of fuel paraffin in the former case was less. As a result, the total olefins and benzene levels in HCCI mode were lower than the corresponding amount observed in SI mode. Aromatic compounds (e.g., toluene), except for benzene, were produced at lower levels in the exhaust when the engine speed and load for both modes were increased.

4

Effects of combustion timing on pressure rise rates in a residual effected HCCI engine

Hunicz Jacek, Gęca Michał, Kordos Paweł, Rybak Arkadiusz

Combustion Engines

|

2019

|

R. 58, nr 3

46--50

EN

Realization of a low temperature combustion concept in homogeneous charge compression ignition (HCCI) engines is a cutting-edge technology that offers clean combustion in parallel with high thermal efficiency. Low combustion temperature prevents from NOx formation whereas homogeneous mixture assures smokeless exhaust. However, achieving the production feasibility by HCCI technology is hampered by high pressure rise rates and the resulting combustion noise at a high load operation. This paper explores combustion timing parameters that are capable of maintaining permissible levels of pressure rise rates under a high load regime. On the basis of experimental data collected at a high load HCCI operation, pressure rise level was correlated with combustion duration. Furthermore, combustion duration has been found to scale with in-cylinder volume, for which 50% of mass fraction burned appeared. The results showed quantitatively limitations of engine load, pointing out on required combustion timings to achieve acceptable combustion harshness depending on engine load.

5

Application of Ion Current Measurement to Identification of Combustion Parameters in a Homogeneous Charge Compression Ignition Engine

Hunicz J., Filipek P., Sobiesiak A.

Metrology and Measurement Systems

|

2018

|

Vol. 25, nr 1

223--234

EN

This study examines the application of ion current measurements to the identification of heat release parameters inside the combustion chamber of a homogeneous charge compression ignition (HCCI) engine fuelled with gasoline. HCCI combustion was achieved with the use of exhaust gas trapping. Combustion parameters derived from the in-cylinder pressure and ion current measurements were compared and analysed. Ion current measurements were accomplished using the existing spark plug and a dedicated electronic circuit. The experiments were performed at a variable excess air ratio and a variable amount of trapped residuals. The results showed a good correlation between peak values of the ion current and heat release rate, except for the cases where a fuel-rich mixture was burnt. The computed ion current integral over the volume of the combustion chamber showed a good agreement with the heat released in the combustion chamber, however this parameter was found to be affected by the amount of trapped residuals. Combustion timing characteristic values computed using heat release and ion current were found to be correlated, however the relationship was not linear.

6

Reduction of pressure rise rates in boosted HCCI engine using advanced valve actuation strategies

Hunicz J., Rybak A., Gęca M.

Journal of KONES

|

2018

|

Vol. 25, No. 4

369--376

EN

Homogeneous Charge Compression Ignition (HCCI) is a promising low temperature combustion technology which offers high fuel efficiency and extremely low exhaust emissions. However, there are still some pending issues to be resolved before the technology will achieve mass production level. Namely, combustion controllability should be improved and HCCI operating range should be widen. The latter is constrained by excessive combustion rates under high loads. In this study, advanced variable valve actuation strategies were applied to control auto-ignition timings and combustion rates. The examinations were conducted using single-cylinder research engine fuelled with directly injected gasoline. The HCCI combustion was achieved using negative valve overlap technique. The engine was run under boosted conditions, in an operation regime where acceptable pressure rise rate (PRR) level is usually exceeded. Selected valve timing sweeps were carried out within a scope of the experiments to evaluate PRR reduction potential. The obtained results manifested superior combustion controllability. Late exhaust valve closing enabled reduction of the amount of internally re-circulated exhaust, which propagated to the main event combustion. From the intake side, two effects were observed, i.e. variability of the intake air aspiration and variability of the apparent compression ratio. Both phenomena were found to affect combustion timings and rates.

7

Numerical investigation into the effect of direct fuel injection on thermal stratification in HCCI engine

Gęca M., Hunicz J., Jaworski P.

Combustion Engines

|

2017

|

R. 56, nr 2

137--140

EN

Despite the fact that HCCI engines are distinguished by mixture homogeneity, some degree of stratification always appears inside a combustion chamber. It is especially applied to residual effect engines utilizing negative valve overlap. Mixture stratification is a result of the imperfect mixing of fresh air with trapped residuals. Direct fuel injection introduces stratification as well, due to fuel vaporization. As a consequence, the temperature within the combustion chamber is uneven. Thermal stratification affects auto-ignition timing and combustion evolution in a high extent. The purpose of this study was to evaluate a degree of thermal stratification in HCCI engine utilizing negative valve overlap. Investigations were performed using three-dimensional CFD model of the combustion system, made by using AVL FIRE software. Simulations were realized for various timings of fuel injection into the cylinder. It was found that fuel injection timing had a significant effect on the thermal stratification and resulting auto-ignition timing.

8

Compression Auto-Ignition Control in a 2-stroke Barrel-type Opposed-Piston Engine

Pyszczek R., Mazuro P., Teodorczyk A.

Archivum Combustionis

|

2017

|

Vol. 37 nr 1

25--42

EN

The aim of this study is to investigate a possibility of Compression Auto-Ignition (CAI) control in a turbocharged 2-stroke barrel type Opposed-Piston (OP) engine fueled with a gasoline. The barrel type OP engine arrangement is of particular interest for the authors because of its robust design, high mechanical efficiency and relatively easy incorporation of a Variable Compression Ratio (VCR). A 3D CFD numerical simulations of the scavenging and combustion processes were performed with use of the AVL Fire solver that is based on a Finite Volume Method (FVM) discretization and offers a number of tools dedicated to numerical simulations of working processes in internal combustion engines. The VCR and water injection were considered for the ignition timing control. A number of cases was calculated with different engine compression ratios, different equivalence ratios and different amount of injected water. Results show that proposed measures should be appropriate for controlling the CAI combustion process. Furthermore, application of these solutions in the real engine can significantly contribute to increase in efficiency and decrease in emissions.

9

Zastosowanie trójfunkcyjnego reaktora katalitycznego spalin do benzynowego silnika HCCI

Hunicz J., Gęca M.

Logistyka

|

2015

|

nr 5

137--144, CD1

PL

W pracy przedstawiono szczegółową analizę składu spalin silnika HCCI (ang.: homogeneous charge compression ignition) zasilanego bezpośrednim wtryskiem benzyny, współpracującego z trójfunkcyjnym reaktorem katalitycznym spalin. Proces spalania HCCI uzyskano z wykorzystaniem ujemnego współotwarcia zaworów i wewnętrznej recyrkulacji spalin. Pomiary składu spalin prowadzono przed i za reaktorem katalitycznym za pomocą systemu analitycznego FTIR. Podczas badań zmieniano obciążenie silnika poprzez zmianę ilości paliwa wtryskiwanego do komory spalania. Wyniki badań pokazały znaczący wpływ obciążenia silnika na skład frakcyjny niespalonych węglowodorów. Wśród analizowanych związków na szczególną uwagę zasługuje metan, gdyż związek ten charakteryzuje się wysoką temperaturą utleniania w reaktorze katalitycznym. Pomiary składu spalin za reaktorem potwierdziły nie tylko małą skuteczność utleniania metanu, ale w pewnych warunkach jego produkcję przez układ oczyszczania spalin. Pomimo obniżenia emisji głównych związków toksycznych, emisja poszczególnych węglowodorów może być kłopotliwa dla zastosowań systemów spalania HCCI w świetle przyszłych norm emisyjnych.

EN

In this study a detailed exhaust analysis was performed for homogeneous charge compression ignition (HCCI) engine fuelled with a direct gasoline injection and equipped with a three-way catalytic converter. HCCI combustion was achieved using a negative valve overlap technique resulting in internal gas re-circulation. Exhaust gases compositions were measured upstream and downstream the catalytic converter using FTIR analytical system. Experimental matrix covered different engine loads achieved via variable amount of fuel injected. Obtained results showed significant effect of the engine load on fractional composition of unburned hydrocarbons. Among analyzed species, methane is one of most important, because it exhibits relatively high oxidation temperature in the catalytic converter. Measurements of exhaust compositions downstream the converter not only proved low performance in terms of methane oxidation, but also production of this compound by exhaust after treatment system under some operating conditions. The results revealed that besides reduction of main exhaust toxic components, excessive emission of methane could pose a challenge for application of HCCI engines in the light of future emission standards.

10

Thermodynamic simulation comparison of AVL BOOST and Ricardo WAVE for HCCI and SI engines optimization

Alqahtani A., Shokrollahihassanbarough F., Wyszynski M. L.

Combustion Engines

|

2015

|

R. 54, nr 2

68--72

EN

The aim of this paper is to compare two simulation software platforms, AVL BOOSTTM and Ricardo WAVETM as used to simulate HCCI and SI GDI engines with the intention of maximising the engine’s efficiency and minimising the emissions. This paper compares these platforms in an experimentally validated model to analyse a spark ignition and a Homogeneous Compression Ignition Charge (HCCI) single cylinder 4 valve gasoline engines with multiple configurations and running parameters in order to find the most optimal set-up for the engine, with the prospect of allowing an optimum engine to be built and tested in real world conditions without the need for multiple expensive prototypes and long delays.

11

Effects of spark assist on HCCI combustion

Hunicz J., Gęca M., Kordos P., Medina A.

Combustion Engines

|

2015

|

R. 54, nr 2

73--77

EN

HCCI (homogeneous charge compression ignition) combustion is initiated by compression temperature and is independent of spark discharge. However, spark discharge can be applied under certain conditions to achieve hybrid combustion, where combustion by flame propagation is followed by auto-ignition of the unburned mixture. Spark assist can be applied to improve combustion stability at low loads or to reduce pressure rise rates under high load regime. In the current study variable spark ignition timing was applied for stoichiometric HCCI combustion, achieved using negative valve overlap technique. Under investigated conditions increase of nitrogen oxides emissions, due to flame propagation, was not observed. To provide more insight into combustion evolution, double Wiebe function was fitted to experimental heat release rates. It was found that only less than 10% of mixture was burned by flame propagation, even for very advanced spark discharge.

12

Experimental and modeling study of the gasoline HCCI engine with internal gas recirculation

Hunicz J., Gęca M.

Silniki Spalinowe

|

2013

|

R. 52, nr 1

3-9

EN

In this study experimental and modeling investigations of a gasoline HCCI engine with internal gas recirculation have been presented. Experimental measurements enabled identification of attainable range of valvetrain settings and air excess coefficient that allows a realization of the HCCI combustion. Factors determining the charge exchange process and the resulting in-cylinder temperature were specified based on computational analysis.

PL

W pracy przedstawiono wyniki badań eksperymentalnych i modelowych procesu roboczego benzynowego silnika HCCI z wewnętrzną recyrkulacją spalin. Na podstawie wyników badań eksperymentalnych określono zakres faz rozrządu oraz współczynnika nadmiaru powietrza, w którym możliwa jest realizacja procesu HCCI. Przeprowadzone badania symulacyjne pozwoliły na zidentyfikowanie czynników kształtujących przebieg wymiany ładunku oraz temperaturę w cylindrze.

13

Eksploatacyjne uwarunkowania wykorzystania eko-obiegu silnika spalinowego

Postrzednik S., Żmudka Z.

Silniki Spalinowe

|

2011

|

R. 50, nr 3

PL

Przedmiotem analizy są możliwości wykorzystania oraz uwarunkowania eksploatacyjne eko-obiegu silnika spalinowego. Zasadniczym warunkiem branym pod uwagę, było kryterium sprawności energetycznej eko-obiegu, w stosunku do sprawności istniejących obiegów klasycznych, a w szczególności stwierdzenie możliwości zwiększenia sprawności układu, głównie w zakresie obciążeń częściowych silnika spalinowego. Wskazano także na oryginalny sposób kontroli zapłonu, w ramach proponowanego systemu HCCI. Uzyskane wyniki potwierdzają postawione tezy.

EN

Use potential and operating conditions of the theoretical eco-cycle of internal combustion engine have been analysed. Energy efficiency of the eco-cycle in relation to efficiency of the classic cycles was the principal criterion taken into consideration. Increase of the eco-cycle efficiency has been found especially within the range of part load of internal combustion engine. The original method of an ignition control for HCCI engine has been presented. Obtained results confirm the made theses.

14

A study of charge exchange in a residual-effected HCCI gasoline engine

Hunicz J.

Silniki Spalinowe

|

2011

|

R. 50, nr 2

25-34

EN

An in-cylinder charge exchange process in a gasoline homogeneous charge compression ignition (HCCI) engine operated in a negative valve overlap (NVO) mode was studied. Research was performed using a single-cylinder research engine with fully variable valve actuation. Combination of in-cylinder pressure traces processing and fluid flow model enables cycle-by-cycle analysis of charge composition and temperature. It allows forecasting of in cylinder pressure volume and temperature-volume histories and can be used for physical-based engine control. In this paper influence of valves timings and valves lifts on the gas exchange process was analyzed. Special attention was paid to the effects of backflows of the in cylinder charge to an intake port.

PL

W artykule przedstawiono wyniki analizy procesu wymiany ładunku w benzynowym silniku HCCI (ang. Homogeneous charge compression ignition) działającym z ujemnym współotwarciem zaworów. Badania eksperymentalne zostały przeprowadzone na jednocylindrowym silniku badawczym wyposażonym w układ zmiany faz rozrządu i wzniosu zaworów. Połączenie analizy ciśnienia indykowanego w cylindrze i modelu przepływu czynnika roboczego pozwala na określanie składu oraz temperatury czynnika w cylindrze z rozdzielczością cyklową. Dzięki temu możliwe jest przewidywanie przebiegów krzywych temperatury i ciśnienia sprężania, co może być wykorzystane do sterowania silnika w oparciu o model fizyczny. W niniejszej pracy dokonano analizy wpływu zmiennych faz rozrządu i zmiennego wzniosu zaworów na proces wymiany ładunku. Szczególną uwagę zwrócono na efekty przepływów zwrotnych z cylindra do kanału dolotowego.

15

Simulation of work of an engine working with combustion initiation from ignition dose of fuel

Sendyka B., Mitianiec W., Noga M.

Journal of KONES

|

2011

|

Vol. 18, No. 3

395-403

EN

The paper presents analysis of fuelling and of the course of combustion process for a two-cycle engine. The main idea of the engine according to patent solution of Prof. B. Sendyka consists in the fact that engine work begins from spark ignition, whereas, at higher load and higher temperature in the cooling system there occurs switching off spark ignition and transition to ignition from an ignition dose injected directly into the combustion chamber. Such an engine possesses two injection systems: one system of multi-point injection which forms homogenous mixture, whereas, the other system of direct injection is used for ignition dose injection only. After injection of the ignition dose of a very small mass combustion is initiated on the basis of formation of auto-ignition centres so as it takes place during knock combustion. Auto-ignition centres initiate combustion of the basic charge. Simulation was carried out in order to perform analysis occurring phenomena of fuel feeding and combustion. Works on it started from elaboration of a computational grid of the engine and subsequently analysis of indicated diagrams of engine work with injection of ignition dose was performed. Analysis was also performed of temperature traces and of traces of charge mass change in the cylinder as well as of participation of the mass of basic fuel dose in the cylinder in function of the crank angle. Moreover visualization of effects of the process of mixture formation and combustion was performed and presented in form of illustrations of charge temperature distribution, fraction of fuel ignition and basic dose vapours in cross-sections of the combustion chamber.

16

Comparison of standard k-ε and RNG k-ε models in flows in 2d model of HCCI engine cylinder

Ahmadi P., Wyszynski M.

Archivum Combustionis

|

2011

|

Vol. 31 nr 1-2

79-96

EN

A computational study of flows in 2D model of four-stroke homogenous charge compression ignition (HCCI) engine cylinder was conducted by standard k-? and renormalization group (RNG) k-? models in FLUENTŽ release 6.2. The primary objective was to evaluate the aforementioned turbulence models for simulation of in-cylinder flows. The engine model was a 2D geometry of a cross section of piston-cylinder assembly, passing through the centres of intake and exhaust valves and parallel to the cylinder axis. Simulation was performed for five consecutive engine cycles under cold-flow assumption and with air as the working fluid. It is generally believed that standard k-? model over-predicts the turbulence kinetic energy, k. The results obtained from the fifth engine cycle at bottom dead centre (BDC) of the intake stroke revealed that below the intake valve and in the near-wall region, standard model estimates up to 26% higher values of k. Overestimation of k by the standard model, results in prediction of higher and less accurate values of turbulent viscosity, ? by this model. Subsequently, in-cylinder flows exhibit large rates of flow deformation, and by definition, RNG model predicts more accurate values of ? in rapidly strained flows. Below the intake valve, ? is predicted up to 53% lower by the RNG model. Therefore, RNG model, in comparison to standard model, is a better approach for computational investigation of in-cylinder flows.

17

A research into a gasoline HCCI engine

Hunicz J., Niewczas A., Kordos P.

Silniki Spalinowe

|

2010

|

R. 49, nr 1

3-13

EN

Homogeneous charge compression ignition (HCCI) is nowadays a leading trend in the development of gasoline internal combustion engines. The application of this novel combustion system will allow to comply with future legislations concerning the exhaust emissions including carbon dioxide. This paper presents a design and implementation of a research engine with a direct fuel injection and the capability of HCCI combustion via an internal gas recirculation and a negative valves overlap (NVO). The technical approach used in the engine allowed an autonomous HCCI operation at variable loads and engine speeds without the need of a spark discharge. Experiments were conducted at a wide range of valve timings providing data which allowed an assessment of a volumetric efficiency and exhaust gas recirculation (EGR) rate. Permissible range of air excess coefficient, providing stable and repeatable operation has also been identified. The use of direct gasoline injection benefited in the improvement of the start of the combustion (SOC) and heat release rate control via the injection timing.

PL

Kontrolowany samozapłon mieszanki paliwowo-powietrznej jest obecnie dominującym kierunkiem rozwoju silników benzynowych. Zastosowanie tego nowego systemu spalania pozwoli na spełnienie przyszłych norm emisji toksycznych składników spalin oraz dwutlenku węgla. W artykule przedstawiono konstrukcję silnika badawczego umożliwiającego realizację obiegu roboczego HCCI z wewnętrzną recyrkulacją spalin uzyskaną przez ujemne współotwarcie zaworów. Zastosowane rozwiązania techniczne umożliwiły autonomiczną pracę silnika w trybie HCCI przy zmiennych obciążeniach i prędkościach obrotowych, bez konieczności wspomagania zapłonu wyładowaniem iskrowym. Przeprowadzenie badań w szerokim zakresie zmian faz rozrządu pozwoliło na ocenę możliwości regulacji napełnienia cylindra i współczynnika reszty spalin. Określono także zakres współczynnika nadmiaru powietrza, w którym uzyskiwana jest stabilna i powtarzalna praca silnika. Zastosowanie bezpośredniego wtrysku benzyny do cylindra pozwoliło na rozszerzenie możliwości kontroli chwili samozapłonu i szybkości wywiązywania się ciepła przez regulację kąta początku wtrysku.

18

Optimization of the combustion chamber in a 2-stroke barrel engine and comparison with 4-stroke classical crankshaft mechanism engine

Mazuro P, Jaworski P, Teodorczyk A

Silniki Spalinowe

|

2009

|

R. 48, SC1

254--265

EN

In the paper, the results of numerical optimization of the combustion chamber of a 2-stroke CI barrel engine are presented and the comparison to a 4-stroke engine with traditional crankshaft mechanism is performed. The optimization is made on the basis of CFD simulations performed for different geometrical models of the combustion chamber, specially designed for the barrel engine. The initial conditions for simulations were assumed taking into account the differences in mixture exchange in the chamber after combustion process for different rotational speeds, density, pressure and wall temperature. The simulations were made for various fuel - gasoline (approximated by C8H17) and diesel (simulated by C13H23) with the use of AVL FIRE software. The target was to create a proper chamber for CI and HCCI mode of combustion system. The results indicated that combustion chambers which were acceptable for CI mode are not appropriate for HCCI mode of engine operation. This comes from the characteristics of chemical reactions and fuel injection. The standard injectors on the market for CI and SI engines have different characteristics of injection, fuel brake up, fuel evaporation and mixing with air. It was found that the well operating combustion chamber with one fuel (for example H8C17), in HCCI mode, is not working well for other fuel, like C13H23. These observations must be confirmed during engine bench tests which are planned for near future. The comparison of a 2-stroke barrel engine with the 4-stroke engine with traditional crankshaft mechanism is based on literature data and shows that properly designed combustion process in the barrel engine with its advantages in construction can give much better results than the engine with traditional crankshaft mechanism. The major advantages are: smaller friction losses, smaller fuel consumption, higher engine efficiency, higher power/weight ratio.

19

A thermo-kinetic model base study on natural gas HCCI engine response to different initial conditions

Jazayeri S., Omid J.

Silniki Spalinowe

|

2009

|

R. 48, nr 1

89-99

EN

Homogenous Charge Compression Ignition (HCCI) combustion is a promising concept to reduce engine emissions and fuel consumption. In this paper, a thermo-kinetic single zone model is developed to study the operation characteristics of a natural gas HCCI engine. The model consists detail chemical kinetics of natural gas oxidation including 325 reactions with 53 chemical species, and is validated with experimental results of reference works. Then, the influence of parameters such as manifold temperature/pressure, and equivalance ratio on incylinder temperature/pressure trends, start of combustion and heat release rate is studied. These results are explained in detail to describe the engine performance thoroughly.

PL

Zaletą silników wysokoprężnych o spalaniu homogenicznym (HCCI) jest możliwość zmniejszenia emisji związków toksycznych i zużycia paliwa. W artykule przedstawiono termokinetyczny jednostrefowy model silnika HCCI zasilanego gazem ziemnym. Model zawiera 325 reakcji chemicznych utleniania i jest skorelowany z wynikami doświadczalnymi uzyskanymi w innych badaniach. Przeanalizowano wpływ na pracę silnika takich parametrów, jak: temperatura i ciśnienie dolotu, współczynnik nadmiaru powietrza w cylindrze, zmiana temperatury i ciśnienia w cylindrze oraz początek zapłonu i szybkość wywiązywania się ciepła. Opisano rezultaty doświadczeń i ich wpływ na pracę silnika.

20

Wpływ temperatury początkowej i składu mieszaniny palnej na pracę silnika HCCI zasilanego biogazem

Motyl K., Lisowski A.

Inżynieria Rolnicza

|

2008

|

R. 12, nr 1(99)

311-317

PL

W pracy przedstawiono wyniki badań wpływu temperatury początkowej i składu mieszaniny palnej na pracę silnika działającego według koncepcji HCCI. Stwierdzono, że istnieje określona wartość temperatury początkowej mieszaniny (około 200°C), po osiągnięciu której dalszy jej wzrost nie powoduje wyraźnego zwiększania ciśnienia maksymalnego spalania, prędkości narastania ciśnienia i opóźnienia samozapłonu. Wartość tej temperatury zależy nieznacznie od składu mieszaniny palnej.

EN

The paper presents results of the research carried out on the impact of initial temperature and combustible mixture composition on work of engine based on the HCCI principle. The researchers found that there is a specific value of the mixture initial temperature (approximately 200°C). When it is reached, further temperature rise does not cause any distinct increase of combustion process maximum pressure, pressure buildup rate and self-ignition delay. This initial temperature value slightly depends on combustible mixture composition.