Particulate emissions from direct-injection and combined-injection vehicles fueled with gasoline/ethanol match-blends – Effects of ethanol and aromatic compositions

Gasoline direct injection (GDI) vehicles are up against the great challenge of particulate emissions, which were mandatorily constrained by the China-6 emission standard. Given the worldwide fuel transition from gasoline to gasoline/ethanol blends, it is important to discuss the effects of ethanol and aromatic contents on particulate emissions of GDI vehicles. In this work, 10% volume of ethanol was added into China-6b gasoline replacing C8 (carbon atoms = 8) alkanes (E10), and the specific aromatic compounds in E10 fuels were adjusted under holding total aromatic content. As there was no limit on individual aromatic compounds in the gasoline standard, the effects of aromatic compounds were investigated over the worldwide harmonized light-duty test cycle (WLTC) with engine cold-start and hot-start at room and low temperatures. For GDI vehicles, the results showed that ethanol substituting part of C8 alkanes in gasoline increased the particulate number (PN) but decreased particulate mass (PM) emissions. For vehicles using the combined port fuel injection (PFI)/GDI injection systems, the PM and PN emissions climbed. Aromatic compositions significantly impacted the particulate emissions. With the concentrations of heavy aromatics increased, PM and PN emissions of both GDI and combined-injection vehicles were shown to multiply.