This study assessed particulate emissions characteristics from two flexible fuel vehicles (FFVs) equipped with port fuel injection (PFI) and gasoline direct injection (GDI) engines. Emissions testing was conducted over the Federal Test Procedure on E10, E51, and E83, and an iso-butanol blend (iBut55). The results showed significantly higher particulate matter (PM) emissions for the GDI-FFV compared to those of the PFI-FFV. The addition of alcohol blends resulted in PM reductions for the GDI-FFV, while PM emissions gradually increased with higher alcohol blending for the PFI-FFV. Elemental carbon (EC) emissions dominated the PM composition for the GDI-FFV, whereas the organic carbon (OC) fraction was higher for the PFI-FFV. The most prominent polycyclic aromatic hydrocarbons (PAHs) in the vapor-phase were the two- and three-ring aromatic compounds, followed by the middle molecular weight PAHs (four-ring compounds). For the particle-phase PAHs, the middle- and high molecular weight PAHs were the most abundant compounds, especially for the GDI-FFV. Overall, the GDI-FFV exhibited markedly higher PAH emissions compared to the PFI-FFV. Both vapor- and particle-phase PAH emissions showed reductions with higher ethanol and iso-butanol fueling for both vehicles, except for the PFI-FFV, where particle-phase PAHs increased and trended similarly with the PM mass and OC for this vehicle. Alcohol blending reduced the carcinogenic potential of the exhaust emissions for both vehicles. The GDI exhaust showed significantly higher metal emissions than the PFI-FFV. The use of higher alcohol blends led to reductions in metal emissions, including redox-active transition metals and other metals originating from the lubricant oil.

这项研究评估了两种配备有港口燃料喷射（PFI）和汽油直接喷射（GDI）发动机的柔性燃料汽车（FFV）的颗粒物排放特性。通过联邦测试程序对E10，E51和E83以及异丁醇共混物（iBut55）进行了排放测试。结果表明，与PFI-FFV相比，GDI-FFV的颗粒物（PM）排放量明显更高。酒精混合物的添加导致GDI-FFV的PM减少，而PFI-FFV的酒精混合物的增加导致PM排放逐渐增加。GDI-FFV的PM成分以元素碳（EC）排放为主，而PFI-FFV的有机碳（OC）比例更高。气相中最突出的多环芳烃（PAH）是二环和三环芳族化合物，其次是中等分子量的PAHs（四环化合物）。对于颗粒相PAH，中分子量和高分子量PAH是最丰富的化合物，尤其是对于GDI-FFV。总体而言，与PFI-FFV相比，GDI-FFV表现出明显更高的PAH排放量。两种车辆的汽相和颗粒相PAH排放均显示出较高的乙醇和异丁醇供油量，但PFI-FFV除外，PFI-FFV的颗粒相PAHs升高且趋势与该车的PM质量和OC相似。酒精混合减少了两辆车的尾气排放的致癌潜力。GDI排气显示出比PFI-FFV高得多的金属排放量。使用高级酒精混合物可减少金属排放，