Effects of oxygenated fuels on the particle-phase compounds emitted from a diesel engine

Two groups of oxygenated fuels with different oxygenated functional groups were selected as the target fuels to be blended with the diesel fuel. The results indicate that both of the diesel-biodiesel (DB) blends and the diesel-biodiesel-ethanol (DBE) blends could reduce particle mass emission rate and particle total number concentration at either low or high engine load. The DBE blends present more significant impacts on suppressing the soot particles on both physical and chemical aspects as compared to the DB blends. The geometrical mean diameter of the particles from either the DB blends or the DBE blends is decreased with the increase of the blending ratio of the oxygenated fuels. Both of the DB blends and the DBE blends have an effective suppression impact on almost all the measured n-alkanes at the high load, but present a promotional impact on the short carbon chains compounds at the low load. Polycyclic aromatic hydrocarbons (PAHs) are significantly suppressed by using the oxygenated fuels, and OH functional group in the DBE blends is observed to have higher oxidation effect on the PAHs than O[sbnd]C[dbnd]O in the DB blends. Moreover, oxygenated fuel blends have a promotional impact on the total measured oxy-PAHs, but present a suppression impact on the total measured nitro-PAHs. However, the impacts of the oxygenated fuels on the individual PAH derivative (oxy- and nitro-PAH) differ among each other.