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1

A study of performance and emissions of SI engine with a two-stage combustion system

Jamrozik A., Tutak W.

Chemical and Process Engineering

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2011

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Vol. 32, nr 4

453-471

EN

Lean mixture burning leads to a decrease in the temperature of the combustion process and it is one of the methods of limiting nitric oxide emissions. It also increases engine efficiency. An effective method to correct lean mixture combustion can be a two-stage system of stratified mixture combustion in an engine with a prechamber. This article presents the results of laboratory research on an SI engine (spark ignition) with a two-stage combustion system with a cylinder powered by gasoline and a prechamber powered by propane-butane gas LPG (liquefied petroleum gas). The results were compared to the results of research on a conventional engine with a one-stage combustion process. The test engine fuel mixture stratification method, with a two-stage combustion system in the engine with a prechamber, allowed to burn a lean mixture with an average excess air factor equal to 2.0 and thus led to lower emissions of nitrogen oxides in the exhaust of the engine. The test engine with a conventional, single-stage combustion process allowed to properly burn air-fuel mixtures of excess air factors X not exceeding 1.5. If the value X > 1.5, the non-repeatability factor COVLi increases, and the engine efficiency decreases, which makes it virtually impossible for the engine to operate. The engine with a two-stage combustion process, working with X = 2.0, the QmlQim = 2.5%, reduced the NOx content in the exhaust gases to a level of about 1.14 g/kWh. This value is significantly lower than the value obtained in a conventional engine, which worked at X = 1.3 with comparable non-repeatability of successive cycles (about 3%) and a similar indicated efficiency (about 34%), was characterised by the emissions of NOx in the exhaust equal to 26.26 g/kWh.

2

Model KIVA-3V jedno- i dwustopniowego systemu spalania w tłokowym silniku ZI

Sosnowski M., Jamrozik A., Kociszewski A., Tutak W.

Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Edukacja Techniczna i Informatyczna

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2010

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T. 5

17-28

PL

W pracy przedstawiono porównanie wyników modelowania obiegu silnika ZI zasilanego mieszanką homogeniczną i realizującego jednostopniowy system spalania z wynikami modelowania obiegu silnika ZI zasilanego mieszanką heterogeniczną i realizującego dwustopniowy system spalania. Do modelowania obiegu silnika wykorzystano program KIVA-3V. Wyniki modelowania wykazały, że w efekcie zubażania homogenicznej mieszanki palnej w silniku z jednostopniowym systemem spalania powyżej λ=1,2, obniżeniu ulegają maksymalne wartości ciśnienia i temperatury obiegu, a przebieg procesu spalania w tym silniku niekorzystnie odbiega od przebiegu spalania mieszanki heterogenicznej w silniku z dwustopniowym systemem spalania o takim samym średnim współczynniku nadmiaru powietrza. Uzyskane charakterystyki szybkości wydzielania ciepła w procesie spalania i sumarycznej ilości ciepła wydzielonego podczas spalania dowodzą, że pomimo znacznego zubożenia mieszanki palnej, dla λ=2,0, proces spalania w tym silniku z dwustopniowym systemem spalania przebiegał dostatecznie szybko, aby możliwe było osiągnięcie odpowiednich osiągów silnika.

EN

This paper compares numerical modelling results of SI engine work cycle powered by homogeneous mixture with single-stage combustion system and SI engine work cycle powered by heterogeneous mixture with two-stage combustion system. The numerical model of the engine work cycle was built using KIVA 3V code. Numerical modelling results of engine work with single stage combustion system and homogenous mixture of average excess air factor greater than λ = 1,2 show decrease in maximal pressure and temperature values of engine cycle. The combustion phenomenon in this engine unfavourably differs from heterogeneous mixture combustion in two-stage combustion system engine of the same average excess air factor. Characteristics of the heat release rate during combustion and the total amount of heat generated during combustion show that despite a significant depletion of fuel mixture for λ = 2,0, the combustion process in the engine with two-stage combustion system was fast enough to reach a suitable engine performance.

3

Numerical analysis of influence of prechamber geometry in IC engine with two-stage combustion system on engine work cycle parameters

Jamrozik A., Kociszewski A., Sosnowski A., Tutak W.

Journal of KONES

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2006

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Vol. 13, No. 2

133-142

EN

Numerical analysis results of influence of prechamber geometry in two stage combustion system SI engine on chosen engine work cycle parameters such as temperature and pressure are presented in the paper. Within the confines of calculations performed in KIVA-3V software, the modelling of processes occurring in combustion chambers of engine with prechamber powered by gasoline for four diameters of the duct connecting the prechamber with cylinder (3mm, 4 mm, 6 mm and 9 mm) were conducted. The research were performed for four values of excess air number equal: 1.4, 1.6, 1.8, 2.0. The modelling results showed that the most favourable case is the configuration with the connecting duct of diameter equal 6 mm. The maximal values of pressure and temperature were obtained during combustion in this engine. The maximal values of pressure and temperature influence the value of maximal indicated pressure and determine the engine performance. Performed simulations of two-stage combustion process delivered information concerning spatial and time-dependent pressure and temperature distribution in combustion chamber of modelled engine.