Effect of heavy aromatic structures on particulates emission of GDI vehicles under WLTC and RDE conditions

Particulate emission reduction is a challenge for GDI vehicles as the more stringent limits have been proposed. Improving fuel quality is an important approach to reducing particulate emissions from gasoline vehicles, but the relationship between gasoline composition and particulate emissions remains unclear. Herein, the PONA analysis and gas chromatography-mass spectrometry combined with complete scanning and selective ion mode were used to accurately resolve the detailed structure of C9-C11 aromatic hydrocarbons in G1 and G2. The results indicate the content of heavy aromatics with a higher boiling point of C10 could be significantly reduced by tightening the content of aromatics and T90. The G1 and G2 were used in emission experimental of 4 GDI gasoline vehicles, demonstrating that the PN emissions were reduced by an average of 65.3 % and 46.6 % under WLTC and RDE conditions, respectively. PN emissions significantly decreased in the low-speed and high-speed stages after gasoline upgrading from G1 to G2. Moreover, PN reduction was mainly observed during rapid acceleration and deceleration stages under RDE conditions, while it showed a significant reduction in all acceleration and deceleration stages under WLTC conditions.The primary particulate core formed by the wet wall effect and inhomogeneous local mixture in the combustion process was significantly reduced by decreasing the content of heavy aromatic hydrocarbons of C10, regarded as the main reason for reduction of PN emissions. This study indicates that tightening T90, specifically reducing the content of C10 heavy aromatics, is crucial for PN emission reduction, providing strong experimental support for the China low carbon fuel upgrades.