Characteristics of Exhaust Diesel Particles from Different Oxygenated Fuels

The characteristic variations of exhaust particles were investigated on a light-duty diesel engine. The commercial diesel fuel (D100) was used as a baseline fuel, and three different oxygenated fuels with the same oxygen content, including a 50% soybean-based biodiesel blend (B50), a 8% dimethyl carbonate blend (DMC8), and a 13% dimethoxy methane blend (DMM13), were tested in this study. From particle size distribution measurement, the oxygenated fuel blends reduce accumulation mode particles (diameter > 50 nm) but increase nucleation mode particles (diameter < 50 nm) in varying degrees compared to the base fuel. The particle size distribution for B50 shows the lowest accumulation mode particle concentration accompanying with the highest nucleation mode particle concentration. From OC/EC (organic carbon/elemental carbon) analysis, three fuel blends reduce the TC (total carbon) emission at a comparable level. With different OC/EC ratios, B50 and DMC8, respectively, produce the most OC and. EC materials. On the basis of thermogravimetric analysis and Raman spectroscopy results, particles from B50 exhibit the highest oxidation reactivity and the most amorphous nanostructure. Particle surface functional groups were also measured using Fourier transform infrared spectroscopy. Particles from oxygenated fuel blends have more oxygen-related surface groups than those from the base fuel, and the DMM13-derirved particles show the highest amount comparing with other tested oxygenated fuels.