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We assessed the engine-out emissions of an ultra-low sulfur diesel (ULSD) and a neat hydrogenated vegetable oil (HVO) from a light-duty diesel truck equipped with common rail direct injection. The vehicle was tested at least twice on each fuel using the LA-92 drive cycle and at steady-state conditions at 30 mph and 50 mph at different loads. Results showed reductions in the engine-out total hydrocarbon (THC), carbon monoxide (CO), nitrogen oxide (NOx), and particulate emissions with HVO. The reductions in soot mass, solid particle number, and particulate matter (PM) mass emissions with HVO were due to the absence of aromatic and polyaromatic hydrocarbon compounds, as well as sulfur species, which are known precursors of soot formation. Volumetric fuel economy, calculated based on the carbon balance method, did not show statistically significant differences between the fuels.

Particulate matter (PM) emitted from gasoline combustion continues to be a subject of research and regulatory interest. This is particularly true as new technology gasoline direct injection (GDI) engines can produce significantly higher levels of PM compared to older technology port fuel injection (PFI) engines. The goal of this study was to conduct a comprehensive literature search and subsequent statistical analysis related to the effects of gasoline properties, such as aromatics, octane indices, and fuel volatility, on PM (mass and number) emissions from PFI and GDI vehicles/engines. The statistical analyses showed a range of positive and negative correlations between different fuel properties and PM mass, total particle number (PN) and solid particle number (SPN) for different engine types (GDI, PFI, and for subdivisions of these engine types), numbers of engine cylinders and driving cycles.