OMEx Fuel and RCCI Combustion to Reach Engine-Out Emissions Beyond the Current EURO VI Legislation 2021-24-0043

Emissions regulations for engine and vehicle manufacturers are bound to become more limiting to prevent greenhouse gas emissions and mitigate the negative effects that potentiate global warming. To fulfill the energy demand necessary in the transportation sector for the short-to-medium term, a parallel optimization of the internal combustion engine, powertrain and fuels is necessary. The combination of novel combustion modes like the reactivity-controlled compression ignition (RCCI), that seeks the benefits of both compression ignition and spark ignition engines, with the so-called e-fuels, that reduce the carbon footprint from well-to-wheel, is worth exploring. This work investigates the potential of the RCCI concept using OMEx-gasoline to reduce the engine-out emissions beyond the current EURO VI legislation. To do so, eight representative operating conditions from several driving cycles for heavy-duty vehicles will be explored experimentally. The engine will be optimized to reach EURO VI engine-out emissions and beyond, and then compare the potential of the OMEx-gasoline and Diesel-gasoline calibrations. The results show that both calibrations can maintain a zero-soot combustion while fulfilling their respective limitation in NOx emissions in all tested conditions. Moreover, the penalty in fuel consumption to reach post-EURO VI levels is generally below 2.5% for the low-to-medium load points and greater than 5% at high load. The CO₂ emissions for both concepts, RCCI diesel-gasoline and RCCI OMEx-gasoline, were evaluated under simplified driving cycles. The results show that in the case of OMEx it is possible to reach the 15% CO₂ reduction target proposed by the European commission for 2025 when the refining process is accounted for using green energies to offset the carbon footprint.