[Emission Characteristics of Gaseous Pollutants from City Bus Fueled with Biodiesel Based on DOC+CDPF Technology in Real Road Conditions].

The gaseous emissions of stage Ⅲ standard City bus with and without DOC+CDPF after-treatment fueled with biodiesel blends on real road in steady-state and transient conditions were studied using OBS-2200 gaseous portable emission measurement. The results showed that B20 led to a decrease of CO and THC emission rates compared with those of B0. In steady-state condition, CO and THC average mass emission rates of B20 decreased by 26.43% and 10.44% respectively and in transient condition the decrease rates were 22.78% and 4.95%. Meanwhile, B20 eventuated in higher CO2 and NOx emission rates. In steady-state condition, CO2 and NOx average mass emission rates of B20 increased by 8.41% and 8.26% respectively and in transient condition the increase rates were 7.15% and 9.13%. DOC+CDPF caused a more obvious reduction of CO and THC emission rates of B20 compared with B0. In steady-state condition, CO and THC average emission rates decreased by 60.58% and 79.92%, while in transient condition they decreased by 63.67% and 82.57%. The influence of DOC+CDPF on emission reduction of CO2 and NOx was not obvious.