Effects of Start Conditions on the Composition of Particle Emissions from a Gasoline Direct Injection Vehicle

Abstract:

Based on a stoichiometric gasoline direct injection (GDI) vehicle certified to China V emission standards, the particulate mass, particulate number, and the composition of particle emissions during New European driving cycle (NEDC) with different start conditions (cold start at 25 ℃, hot start at 25 ℃ and cold start at 5 ℃) was investigated. The results show that particulate mass，number and copositions are significantly affected by start conditions i.e. the GDI vehicle bring higher particulate mass and number emission when cold start at 5 ℃, 81 percent of total carbon (TC) is organic carbon (OC) when cold start at 25 ℃, OC percentage changes little when hot start, but decreases 15 percent at 5 ℃. Soluble organic fractions (SOF) are mainly composed of fatty acids and alkanes, SOF components change little when hot start, but PAHs fractions increase 24 times at 5 ℃; Fatty acids are mainly composed of C16:0 and C18, start conditions and ambient temperature have little effect on fatty acids components; Alkane are mainly composed of C24H50、C25H52、C26H54 and C27H56, alkane components change little when hot start, but change greatly at 5 ℃; PAHs are mainly composed of middlering PAHs and highring PAHs, and these fractions changed greatly when hot start at 25 ℃ and cold start at 5 ℃.