Combustion and emission analysis of a passive turbulent jet ignition engine fueled with wet ethanol

The elevated global attention around GHG emissions in recent years have driven regulatory bodies to the creation of ever-increasing standards. Research suggests that combining biofuels, such as ethanol, with advanced combustion techniques, such as pre-chamber ignition systems, offers a promising path for the development of internal combustion engines for light vehicles among these tightening standards. For pre-chamber systems, a separate cavity is employed where the combustion is initiated before the partially burned gases are ejected through connecting orifices into the main combustion chamber. These gases carry high levels of kinetic, thermal, and chemical energy, increasing turbulence in the main chamber and reducing combustion duration and ignition delay. Aiming to analyze the influence of pre-chamber material, internal volume, and orifice configuration over combustion characteristics, two values of internal volume and two configurations of orifices were combined into four distinct pre-chamber geometries. These were machined in both stainless steel l304 and a copper–chromium–zircon (CuCr1Zr) alloy, totaling eight articles. Utilizing an AVL 5495 single-cylinder research engine (SCRE) operating at 14:1 compression ratio and E96 fuel, the pre-chambers were, then, installed and tested for two operating conditions of engine speed and load. The clearance volume was adjusted as to compensate for the added volume of the pre-chamber. An analysis of the results indicated reductions of NO X emissions of up to 73% in addition to improvements in fuel conversion efficiencies of up to 2%. Furthermore, reductions of up to 15% in combustion duration were observed, reducing tendencies to knocking. This improvement also allows for future increases in compression ratios, thereby, enhancing fuel conversion efficiency. The obtained results also indicate that the optimal pre-chamber design is highly dependent in the engine’s operation conditions.