Understanding particles emitted from spray and wall-guided gasoline direct injection and flex fuel vehicles operating on ethanol and iso-butanol gasoline blends

ABSTRACTTraffic-related pollutants are an ever-growing concern. However, the composition of particle emissions from new vehicle technologies using relevant current and prospective fuel blends is not known. This study tested four current and up-and-coming vehicle technologies with nine fuel blends with various concentrations of ethanol and iso-butanol. Vehicles were driven on both the federal test procedure (FTP) and the unified cycle (UC). Additional tests were conducted under steady-state speed conditions. The vehicle technologies include spray-guided gasoline direct injection (SG-GDI), wall-guided gasoline direct injection (WG-GDI), port-fuel injection flex fuel vehicle (PFI-FFV), and a wall-guided GDI-FFV. The fuels consisted of 10–83% ethanol and 16–55% iso-butanol in gasoline. The composition of soot, water-insoluble mass (WIM), water-soluble organic mass, and water-insoluble organic mass (WIOM), and OM was measured. The majority of emissions over FTP and UC were water-insoluble (>70%), and WIOM cont...