Time-resolved Emission Characteristics of Gasoline Vehicle Particle Number and Size Distributions

Particle emissions of seven gasoline vehicles were measured using an electrical low-pressure impactor (ELPI) over the new European driving cycle (NEDC). Two dilution systems were utilized: one is constant volume system (CVS) for constant exhaust volume and the other is ejector dilutor for constant dilution ratio. Then the time-resolved number concentration, size distributions and total particle number were obtained. The effects of misfire rate and oxygen sensor failure on the particle emission were also studied in order to primarily examine the on-board diagnoses of particle number emission of gasoline vehicle.

The results indicate that the particles emitted by gasoline vehicles are mainly in the form of nuclei mode in diameter range from 7 nm to 55 nm. The specific number emissions vary from 1.56×10¹³ to 8.42×10¹³ particles/km and GMD ranges from 27 to 50nm. Higher misfire rate results in lower total particle number emission while oxygen sensor failure deteriorates the particle number emission of gasoline vehicle.