Study on effects of split injection proportion on hydrogen mixture distribution, combustion and emissions of a gasoline/hydrogen SI engine with split hydrogen direct injection under lean burn condition

Split hydrogen direct injection is proved to be a better way to use the hydrogen in the engine. Therefore, a numerical study on effects of split injection proportion on hydrogen mixture distribution, combustion and emissions was presented of a gasoline/hydrogen SI engine with split hydrogen direct injection to investigate the principle of split hydrogen direct injection. Under lean burn condition, six different split injection proportions achieve six kinds of hydrogen mixture distribution, which affect the engine performance a lot. With split hydrogen direct injection, the mixture nearby the spark plug is denser and in other zone is more homogeneous at the same time, which achieve better performances of both efficiency and emissions. As the first injection proportion increases, the cylinder pressure climbs to the highest with first injection proportion of 33% and the NOx, CO and HC emissions decrease continually. When the first injection proportion is 75%, the NOx, CO and HC emissions are respectively 31.6%, 79.3% and 40.6% less than those of single hydrogen direct injection.