Abatement potential analysis on CO₂ and size-resolved particle emissions from a downsized LPG direct injection engine for passenger car

As global warming and fine dust problem became issues, the regulation for relevant exhaust emissions has been strengthened gradually. Thus, a major challenge of automotive engineers is reducing the CO₂ and particle emissions at the same time. Especially for gasoline direct injection (GDI) engines, which are widely used due to its higher fuel efficiency, an excessive particle emissions problem compared to port fuel injection system is the big nuisance. The LPG fuel, which has great fuel properties for applying this direct injection scheme, could deal with this. Also, downsized turbocharged system can reduce additional fuel consumption and CO₂ emissions sequentially. In this study, a GDI passenger car and the same vehicle equipped with a downsized turbocharged liquefied petroleum gas direct injection (T-LPDi) engine were evaluated under chassis dynamometer test to verify the exhaust emission abatement capability of T-LPDi vehicle. The T-LPDi engine was developed for research use, which has dedicated fuel supply and control strategy for LPG fuel. Comparing the T-LPDi and GDI vehicles, the CO₂ emissions were decreased by > 20% under the vehicle test condition, while particle number and mass emissions were decreased by > 90% and >50% from the T-LPDi vehicle respectively. These results showed a potential of T-LPDi concept as a good alternative with the environmental competitiveness, though there is room for further improvement of engine control and optimization of emission catalyst to meet more stringent future regulations.