Demonstration of 2027 Emissions Standards Compliance Using Heavy-Duty Gasoline Compression Ignition with P1 Hybridization

Heavy-duty on-road engines are expected to conform to an ultralow NOx (ULNOx) standard of 0.027 g/kWh over the composite US heavy-duty transient federal test procedure (HD-FTP) cycle by 2031, a 90% reduction compared to 2010 emissions standards. Additionally, these engines are expected to conform to Phase 2 greenhouse gas regulations, which require tailpipe CO₂ emissions under 579 g/kWh. This study experimentally demonstrates the ability of high fuel stratification gasoline compression ignition (HFS-GCI) to satisfy these emissions standards. Steady-state and transient tests are conducted on a prototype multi-cylinder heavy-duty GCI engine based on a 2010-compliant Cummins ISX15 diesel engine with a urea-SCR aftertreatment system (ATS). Steady-state calibration exercises are undertaken to develop highly fuel-efficient GCI calibration maps at both cold-start and warmed up conditions. A P1 hybrid architecture is proposed to enable the use of an integrated starter generator (ISG) capable of spinning the engine up to idle speeds and an electrically heated ATS for fast heat-up and better thermal management. The combined solution is shown to satisfy the aforementioned ULNOx standard across the composite HD-FTP while decreasing the CO₂ emissions compared to the 2013 baseline values, cementing the credentials of low-cetane fuels as viable, near-term alternatives to diesel fuel in heavy-duty on-road engines.