Effects of aromatics, olefins and distillation temperatures (T50 & T90) on particle mass and number emissions from gasoline direct injection (GDI) vehicles

Fuel quality is among the primary reasons for severe vehicular pollution. A limited understanding of the effects of gasoline properties on modern vehicle emissions is one obstacle for the establishment of stricter fuel standards in China. This study evaluated the effects of aromatic and olefin contents and T50 and T90 (defined as the 50%v and 90%v distillation temperatures) on tailpipe emissions from two gasoline direct injection (GDI) vehicles compliant with China 4 standards. Both gaseous and particulate emissions using different types of gasoline were measured. Changing aromatic and olefin contents had relatively small impacts on fuel consumption. Compared with olefins and T90, the regulated gaseous emissions were impacted more by aromatics and T50. Evident decreases of the particle mass (PM) and particle number (PN) emissions were found when the aromatic content and T90 decreased. Reducing the olefin content slightly decreased the PM emissions and increased the PN emissions. With decreasing T50, the PM emissions increased and the PN emissions slightly decreased. The results suggest that aromatic content and T90 should be decreased to reduce particle emissions from GDI vehicles. This study also provides some other suggestions for how to improve gasoline quality in China.