Study on emission characteristics of hybrid buses under driving cycles in a typical Chinese city

In this study, a hybrid city bus was taken as the research object, and through a vehicle drum test, the hybrid bus emissions, the transient gas pollutant emissions, and the particle size and number distributions were surveyed. This study shows that compared to traditional fuel buses, hybrid buses can reduce approximately 44% of NOX emissions, 33% of total hydrocarbon emissions, and 51% of particle emissions. Furthermore, the particle number concentration of the test vehicle was increased in the middle and low ranges of the study. More specifically, the particle number concentration mainly corresponded to particles with a size in the range from 0.021 to 0.755 μm, with a maximum of 0.2 μm, and a particulate matter with particle size of less than 1.2 μm accounted for 95% of the total emissions. Particulate mass concentration was increased as the particle size increased, and the maximum value corresponded to particulate matter with a size of 6.2 μm. On average, whether using a traditional fuel bus or a hybrid...