Combustion analysis of a SI engine with stratified and homogeneous pre-chamber ignition system using ethanol and hydrogen

•Pre chamber ignition systems provide more combustion stability and efficiency.•The combustion efficiency is even higher in stratified pre-chambers.•Pre chambers increase the heat release rate and combustion is faster.•Pre chamber can be more beneficial when associated with lean mixtures. Environmental regulations have been increasingly demanding reduction of fossil fuel consumption and emission in industrial activities and in the transportation sector. In this context, the use of biofuels such as ethanol has become increasingly attractive. With similar purpose, several technologies have been explored, among which stands out the pre-chamber ignition system. In this context, this paper aims to evaluate the viability of pre-chamber system use in a commercial SI engine, considering combustion and emission analysis of both homogeneous and stratified with hydrogen injection pre-chamber systems. To conduct this research, a flex-fuel engine under stoichiometric conditions and ethanol as fuel in main chamber was used. In this work it was identified that the use of pre-chambers can reduce the combustion time by up to 20%, increase the thermal efficiency by up to 5% and reduce CO and NOx emissions by up to 12% and 33% respectively, when compared to the baseline ignition system, without significant changes in the combustion efficiency. Moreover, the research proves that output power in stoichiometric mixtures can be increased with the use of both pre-chamber ignition systems.