This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Turbulent jet ignition Effect on Exhaust Emission and Efficiency of a SI Small Engine Fuelled with Methane and Gasoline
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 27, 2020 by SAE International in United States
Pollutant emission of vehicle cars is nowadays a fundamental aspect to take into account. In the last decays, the company have been forced to study new solutions, such as alternative fuel and learn burn mixture strategy, to reduce the vehicle’s pollutants below the limits imposed by emission regulations. Pre-chamber ignition system presents potential reductions in emission levels and fuel consumption, operating with lean burn mixtures and alternative fuels. The aim of this work is to study the evolution of the plasma jets in a different in-cylinder conditions. The activity was carried out in a research optical small spark ignition (SI) engine equipped alternatively with standard ignition system and per-chamber. The engine runs at 2000 rpm at wide open throttle (WOT) in standard ignition condition and slightly turbocharged in prechamber condition in order to overcame the decrease of compression ratio. In this activity methane and gasoline were used. Methane was always injected in the pre-chamber and ignited by spark plug; meanwhile methane and gasoline were injected, alternatively, in the main chamber by port fuel injection (PFI) mode. The combustion of the pre-chamber methane mixture generates four plasma jets that quickly ignite the mixture made alternatively with methane/air and gasoline/air into the combustion chamber. For both conditions the flame speed was much faster than the traditional ignition (gasoline injected in PFI without pre-chamber). Using optical data, significant information about the flame propagation in terms of the speeds and radius were obtained both when using methane and when using gasoline in the main chamber. The optical data were correlated with the engine performance and indicated measurements that showed an increase Indicated mean effective pressure (IMEP) and Coefficient of Variation (CoV) reduction for both mixture of fuels used. Furthermore the effect of pre-chamber ignition on the engine stability and efficiency in stoichiometric and lean-burn operation conditions was investigated.