Numerical Study on Combustion and Emission Characteristics of a PFI Gasoline Engine with Hydrogen Direct-Injection

In this paper, the effects of hydrogen blending radio and EGR rate on combustion and emission characteristics of a PFI gasoline engine with hydrogen direct-injection have been investigated by numerical modelling methods using a new generation of CFD simulation software CONVERGE. Results showed that compared with original engine, hydrogen direct-injection PFI gasoline engine had a better performance on combustion characteristics, but it also had a disadvantage of increasing NOx emissions. With the increase of hydrogen blending radio, combustion duration shortened and CA50 advanced and was closer to TDC. And CO and THC emissions decreased, however NOx emission increased. The variations of the combustion and emission characteristics followed by the increase of the EGR rate were exactly the opposite to the change of hydrogen blending radio. Considering both the combustion and emission characteristics, using moderate EGR rate (15%~20%) under high hydrogen blending radio (15%~20%) condition can realize the simultaneous improvement of combustion and emission performance.