Research of a Combustion Process in a Spark Ignition Engine, Fuelled With Gaseous Fuel Mixtures

Melaika, Mindaugas

doi:10.20334/2403-m

Cited by 8 publications

(1 citation statement)

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“…Due to different type of researches and versatile results of DI system, there is still lack of information on comparison related with combustion imaging and emissions chemiluminescence in ICE between three main combustion modes: homogenous stoichiometric, homogenous lean burn and stratified lean burn. Previous studies on gas DI [64] focused on the DI system and engine adjustable parameters such as the spark timing, injection timing, and injection duration. These earlier studies [60] also focused mainly on stratified combustion at low engine speeds and several combustion process time steps.…”

Section: Emissions Spectra During Combustionmentioning

confidence: 99%

Experimental Investigation of Methane Direct Injection with Stratified Charge Combustion in Optical SI Single Cylinder Engine

Melaika

Dahlander

2016

SAE Technical Paper Series

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N atural gas, biogas, and biomethane are attractive fuels for compressed natural gas (CNG) engines because of their beneficial physical and chemical characteristics. This paper examines three combustion modes-homogeneous stoichiometric, homogeneous lean burn, and stratified combustion-in an optical single cylinder engine with a gas direct injection system operating with an injection pressure of 18 bar. The combustion process in each mode was characterized by indicated parameters, recording combustion images, and analysing combustion chemiluminescence emission spectra. Pure methane, which is the main component of CNG (up to 98%) or biomethane (> 98 %), was used as the fuel. Chemiluminescence emission spectrum analysis showed that OH* and CN* peaks appeared at their characteristic wavelengths in all three combustion modes. The peak of OH* and broadband CO 2 * intensities were strongly dependent on the air/fuel ratio conditions in the cylinder. Lower OH* and CO 2 * intensities were observed with lean air/fuel mixtures because under these conditions, more air was present, the combustion reactions were slower, and the cylinder pressure was higher. CN* was formed by the spark plasma and was detected over a particularly long period when using a dual coil ignition system. The intensities of the OH* and CN* signals correlated when using this ignition system. Combustion image analysis showed that the flame had a wrinkled boundary in stoichiometric and lean burn modes and was especially distorted in stratified mode. No yellow soot luminescence was observed during homogeneous combustion. However, the emission spectra and combustion images acquired during stratified combustion showed that soot formation occurred due to the presence of fuel-rich areas with inadequate mixing in the cylinder. The difficulty of maintaining stable fuel injection, achieving proper air/fuel mixing, and ensuring stable flame propagation in lean air/fuel mixtures increased cycle-to-cycle variations. However, the homogeneous lean burn and stratified combustion modes achieved significantly lower indicated specific fuel consumption values than stoichiometric combustion.

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Section: Emissions Spectra During Combustionmentioning

confidence: 99%