Study of the combustion behavior of a spark ignition engine fueled with synthetic gases: Optical characterization and in-cylinder experimental investigations

Resumo

© 2017 IMEKOThe combustion process of a single cylinder research engine with optical access, four stroke with port fuel injection (PFI) and spark ignition (SI), was experimentally investigated. It was fueled with methane as baseline fuel and compared with a mixture of Syngas (blend of hydrogen, methane, carbon monoxide, carbon dioxide and nitrogen). The in-cylinder pressure and the related parameters were analyzed as indicators of the combustion behavior. Digital imaging measurements with OH filter were performed to evaluate the flame propagation. Therefore, UV chemiluminescence is applied to follow the OH radicals formation in the flame front from spark ignition to the cylinder walls through an optical access in the combustion chamber. The engine was operated at 900 rev/min, with the throttle being held in the partial-open position to get 7 mbar inlet pressure. The spark timing was set at 7° crank angle (CA) before top dead center (BTDC), and a stoichiometric air/fuel ratio was considered. For syngas blend the results suggest an increase in the combustion duration, with a difference in peak pressures and center of combustion location of 1.81ºCA and 1.99ºCA respectively, compared with methane. The cyclic variations in the combustion process were around 3% for both fuels, indicating a stable combustion process.

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