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Biodiesel as a renewable energy is becoming increasingly attractive due to the growing scarcity of conventional fossil fuels. Meanwhile, the development of after-treatment technologies for the diesel engine brings new insight concerning emissions especially the particulate matter pollutants. In order to study the coupling effects of biodiesel blend and CCRT (Catalyzed Continuously Regeneration Trap) on the particulate matter emissions, the particulate matter emissions from an urban bus with and without CCRT burning BD0 and BD10 respectively was tested and analyzed using electrical low pressure impactor (ELPI). The operation conditions included steady state conditions and transient conditions. Results showed that the particulate number-size distribution of BD10 and BD0 both had two peaks in nuclei mode and accumulation mode at the conditions of idle, low speed and medium speed while at high speed condition the particulate number-size distribution only had one peak.

Based on pure diesel, pure biodiesel, and two biodiesel blends at volumetric mixture ratio of 10% and 20%, NEDC emission tests were carried out on a Euro 3-compliant diesel car. Results showed that pure biodiesel and biodiesel blends had decreasing effects on CO and HC emissions under warm-up situations, but deteriorations of CO and HC emissions were observed under cold start-up and low vehicle speed operating conditions, and this caused increasing results of CO and HC emission factors in NEDC tests when substituting pure diesel with both of pure biodiesel and biodiesel blend of 20%. Pure biodiesel aroused an increase in NOX emissions compared with pure diesel, but the two low mixture ratio biodiesel blends were observed in different increasing effects and even decreasing effects on NOX emissions. Only pure biodiesel had limited increasing effects on CO₂ emissions.

In this study, the real-world NOx and particle emissions of buses burning pure diesel fuel (D100), biodiesel fuel with 20% blend ratio (B20) and liquefied natural gas (LNG) were measured with portable emission measurement system (PEMS). The measurement conducted at 6 constant speed, which ranged from 10km/h to 60 km/h at 10km/h intervals, and a period of free driving condition. The relationship between vehicle specific power (VSP) and NOx/particle emissions of each bus were analyzed. The results show that the change rules of NOx, PN and PM emission factors with the increase of VSP were basically the same for the same bus, but for the bus using different fuel, the change rules may change. In VSP bin 0, the vehicles were mostly in idle condition and the emission factors of NOx, PN and PM of three buses were all in a relatively high level. In low VSP interval, which ranged from bin 0 to bin 4, the emissions of three buses first decreased and then increased with the growth of VSP.