The effects of diesel particulate filters and a low-aromatic, low-sulfur diesel fuel on emissions for medium-duty diesel trucks

The effects of diesel particulate filters (DPFs) on regulated emissions and organic species were measured for several medium-duty diesel vehicles. Vehicles were measured in three configurations: a baseline California in-use diesel fuel, a low-aromatic, low-sulfur diesel fuel, and a DPF with a low-aromatic, low-sulfur diesel and a more commercial low-sulfur diesel fuel. The organic species measurements included C1–C13 hydrocarbon species, C1–C8 carbonyls, and semi-volatile and PM-based polycyclic aromatic compounds (PACs). Tests on vehicles operating with DPFs showed reductions ranged from 89±2.3% to 98±0.7% for PM, 72±2.5% to 80±0.6% for THC, and 81±1% to 90%±1.3 for CO. Although some fuel effects were observed, they were considerably smaller than those found for the DPFs. Detailed C1–C13 organic gas measurements showed alkenes and carbonyls to be the most prominent compound classes, with formaldehyde, ethene, acetaldehyde, and ethyne having the highest emission rates. Large reductions in alkenes, alkynes, and aromatics were found for the DPF, with smaller reductions also found for alkanes and carbonyls. Total PAC emissions were 4.34, 2.25, and 0.69 mg/mi, respectively, for the baseline fuel, the low-aromatic, low-sulfur diesel fuel and DPF with low-sulfur diesel fuel. The majority of the PACs were found in the semi-volatile phase.