Size distribution of EC, OC and particle-phase PAHs emissions from a diesel engine fueled with three fuels.

The size distribution of elemental carbon (EC), organic carbon (OC) and particle-phase PAHs emission from a direct injection diesel engine fueled with a waste cooking biodiesel, ultra low sulfur diesel (ULSD, 10-ppm-wt), and low sulfur diesel (LSD, 400-ppm-wt) were investigated experimentally. The emission factor of biodiesel EC is 90.6 mg/kh, which decreases by 60.3 and 71.7%, compared with ULSD and LSD respectively and the mass mean diameter (MMD) of EC was also decreased with the use of biodiesel. The effect of biodiesel on OC emission might depend on the engine operation condition, and the difference in OC size distribution is not that significant among the three fuels. For biodiesel, its brake specific emission of particle-phase PAHs is obviously smaller than that from the two diesel fuels, and the reduction effect appears in almost all size ranges. In terms of size distribution, the MMD of PAHs from biodiesel is larger than that from the two diesel fuels, which could be attributed to the more effective reduction on combustion derived PAHs in nuclei mode. The toxicity analysis indicates that biodiesel could reduce the total PAHs emissions, as well as the carcinogenic potency of particle-phase PAHs in almost all the size ranges.