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Wyszukujesz frazę "charge compression" wg kryterium: Temat


Wyświetlanie 1-9 z 9
Tytuł:
Analysis of the ignition control in the HCCI system using dose of monoatomic inert gas
Autorzy:
Postrzednik, S.
Przybyła, G.
Żmudka, Z.
Tematy:
IC engine
HCCI system
ignition control
charge compression
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/248032.pdf  Link otwiera się w nowym oknie
Opis:
The subject of the analysis presented in the paper is the idea and implementation method of the ignition point of homogeneous air-fuel mixture, used in the IC engine with HCCI system. Autoignition of the combustible mixture can occur only upon reaching the characteristic self-ignition temperature Tz. It should take place during (near end) the load compression. In order to achieve the fuel mixture ignition temperature Tz in the system, usually it is proposed adjusting the engine compression ratio, epsilon. However, it is quite cumbersome especially in case of frequent changes of engine load (there are also difficulties with the precise advance angle adjusting of fuel mixture ignition). According to our conception, the other method of autoignition adjustment can be successfully applied. The essence of the new idea consists in proper selection, according to engine load, of the exponent k of charge polytropic compression. Introducing the defined dose of monoatomic gas (e.g. argon Ar,k almost equal 1.667) to air-fuel mixture, the higher values of the polytropic compression exponent .. of working medium can be achieved. It will result in significant increase of the temperature rise Delta Tmax of the compressed charge and accordingly progressive increase of the advance angle of the mixture ignition.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of engine speeds and dimethyl ether on methyl decanoate HCCI combustion and emission characteristics based on low-speed two-stroke diesel engine
Autorzy:
Wang, Shiye
Yao, Li
Tematy:
homogeneous charge compression ignition (HCCI)
methyl decanoate (MD)
dimethyl ether (DME)
speed
NOx emission
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Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:
https://bibliotekanauki.pl/articles/258938.pdf  Link otwiera się w nowym oknie
Opis:
The combustion and emission characteristics of homogeneous charge compression ignition (HCCI) fuelled by methyl decanoate (MD) with different engine speeds and dimethyl ether (DME) mixing ratios are investigated in this work. Engine data of a MAN B&W 6S70MC low-speed two-stroke marine diesel engine were used for the reactor. The results show that a decrease of engine speed has little effect on the in-cylinder temperature and pressure of the engine at constant excess air coefficient of 1.5. Meanwhile, NOx emissions decrease with a decrease of engine speed in pure MD HCCI combustion. The results also indicate that NOx and CO2 emissions decrease significantly with an increase in the percentage of DME in MD and DME mixing combustion at a constant total mole fraction and engine speed of 85 revolutions per minute (r/min).
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combustion control in gasoline HCCI engine with direct fuel injection and exhaust gas trapping
Autorzy:
Hunicz, J.
Tematy:
homogeneous charge compression ignition
variable valve timing
negative valve overlap
gasoline
direct injection
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/246912.pdf  Link otwiera się w nowym oknie
Opis:
Homogeneous charge compression ignition (HCCI) seems to be the most promising solution for gasoline engines in the light of future emissions regulations. This novel combustion technique allows for significant reduction of fuel consumption and engine-out NOX emissions at low and medium engine load/speed conditions. High heat release rate enables realization of the Otto cycle close to ideal, increasing thermal efficiency. Among different approaches to invoke an auto-ignition of air-fuel mixture, exhaust gas trapping with the use of a negative valve overlap is under intensive investigations. The paper presents research results ofcontrolling an auto-ignition and combustion phasing in a single cylinder gasoline engine with direct fuel injection operated in the negative valve overlap mode. The experiments were performed at variable valvetrain settings, providing a control of EGR rate and volumetric efficiency. Additionally, the combustion process was investigated at variable air-fuel ratio. It was found that volumetric efficiency and EGR ratę are mainly dependent on exhaust valve timing, while a timing of intake valve determined combustion on-set and its duration. The effects of EGR rate and air-fuel ratio on combustion timing and exhaust gas emissions were isolated. The direct fuel injection showed its benefits versus mixture formation outside the cylinder. The application of variable injection timing provided additional possibility to control the combustion timing and exhaust emissions. However, it was found that the fuel injection strategy should be related to the engine load conditions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of spark assist on HCCI combustion
Autorzy:
Hunicz, J.
Gęca, M.
Kordos, P.
Medina, A.
Tematy:
HCCI
homogeneous charge compression ignition
spark assist
double Wiebe
silnik wysokoprężny o spalaniu homogenicznym
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Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Powiązania:
https://bibliotekanauki.pl/articles/134201.pdf  Link otwiera się w nowym oknie
Opis:
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.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic simulation comparison of AVL BOOST and Ricardo WAVE for HCCI and SI engines optimization
Autorzy:
Alqahtani, A.
Shokrollahihassanbarough, F.
Wyszynski, M. L.
Tematy:
HCCI
homogeneous charge compression ignition
SI
numerical simulation
software platform
AVL BOOST
Ricardo WAVE
silnik wysokoprężny o spalaniu homogenicznym
silnik ZI
symulacja numeryczna
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Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Powiązania:
https://bibliotekanauki.pl/articles/133607.pdf  Link otwiera się w nowym oknie
Opis:
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.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD modelling of combustion in HCCI engine using avl fire software
Autorzy:
Jamrozik, A.
Tematy:
spalanie
zapłon
czas zapłonu
homogenous charge compression ignition
exhaust gas recirculation (EGR)
heat release rate
start of the ignition
burn duration
injection timing
conventional compression ignition engine
indicated pressure
nitric oxide
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Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Powiązania:
https://bibliotekanauki.pl/articles/410680.pdf  Link otwiera się w nowym oknie
Opis:
HCCI (Homogenous Charge Compression Ignition) combustion system is now one of the most promising solutions used in piston engines. The paper presents the results of three-dimensional modeling of combustion in the single cylinder HCCI engine powered with Diesel fuel. 3D modeling was performed in AVL Fire code. The basic combustion parameters including start of the ignition (SOI), burn duration (BD), indicated pressure (pi) and nitric oxide (NO) and soot (Soot) emissions were analyzed. The modeling results show that combustion process in HCCI engine compared to a conventional engine with compression ignition is characterized by an earlier ignition (SOI) and shorter burn duration (BD). The impossibility of controlling HCCI combustion process leads to deterioration of engine performance and increased emissions of harmful exhaust gas components. Calculations showed that for the same equivalence ratio of burn mixture, uncontrolled HCCI combustion compared to a controlled combustion in engine with fuel injection operated is characterized by higher NO emission and reduced Soot emission.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation into the effect of direct fuel injection on thermal stratification in HCCI engine
Autorzy:
Gęca, M.
Hunicz, J.
Jaworski, P.
Tematy:
homogeneous charge compression ignition
HCCI
direct injection
thermal stratification
computational fluid dynamics
CFD
silnik wysokoprężny o spalaniu homogenicznym
wtrysk bezpośredni
stratyfikacja termiczna
obliczeniowa mechanika płynów
Pokaż więcej
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Powiązania:
https://bibliotekanauki.pl/articles/133917.pdf  Link otwiera się w nowym oknie
Opis:
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.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrocarbon species in SI and HCCI engine using winter grade commercial gasoline
Autorzy:
Elghawi, Usama
Mayouf, Ahmed
Tsolakis, Athanasios
Tematy:
homogeneous charge compression ignition
HCCI
gas chromatography-mass spectrometry
GC-MS
hydrocarbon speciation
regulated emissions
unregulated emissions
zapłon samoczynny mieszanki jednorodnej
chromatografia gazowa ze spektrometrią mas
specjacja węglowodoru
emisje regulowane
emisje nieregulowane
Pokaż więcej
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Powiązania:
https://bibliotekanauki.pl/articles/2097456.pdf  Link otwiera się w nowym oknie
Opis:
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.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the Striker Material on the Results of High-Speed Impact at a Barrier
Autorzy:
Voitenko, Yuri
Zakusylo, Roman
Zaychenko, Stefan
Tematy:
porosity
striker
shaped charge
shock compression
penetration
shock wave front
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Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Powiązania:
https://bibliotekanauki.pl/articles/27787968.pdf  Link otwiera się w nowym oknie
Opis:
In this work the influence of the characteristics of the material of the striker (cumulative jet or projectile), moving at speeds of 2-10 km/s, on the volume of the resulting crater in a metal target, has been studied. The dependence of the crater volume in an aluminum alloy target of Cu-Al, W-Cu-Pb-Al composites, and steel St45 for a PTFE-Cu composite, were investigated. The outer diameter and height of the shaped charges were 26 and 28, and 31 and 33 mm, respectively. The mass of the explosive (phlegmatized hexogen) in these charges was 10 and 18 g. A comparison was made between the ratios of the kinetic energy of the striker to the volume of the crater formed for the composites PTFE-Al, PTFE-Cu, Cu-Al, Ni-Al, W-Cu-Pb, and porous materials Cu and Al. It was demonstrated that the chemical interaction of the components of the porous Cu-Al and Ni-Al composites during penetration into the barrier is possible at an impact velocity of at least 2-3 km/s and a porosity of at least 30%.
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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