흡기밸브 닫힘시기 지각과 운전조건이 2단 분사 PCCI 엔진에 미치는 영향에 관한 연구

As world attention has focused on global warming and air pollution, high efficiency diesel engines with low CO2 emissions have become more attractive. Premixed diesel engines in particular have the potential to achieve the more homogeneous mixture in the cylinder which results in lower NOx and soot emission. Early studies have shown that the operation conditions such as the EGR, intake conditions, injection conditions and compression ratio are important to reduce emissions in a PCCI (Premixed Charge Compression Ignition) engine. In this study a modified cam was employed to reduce the effective compression ratio. While opening timing of the intake valve was fixed, closing timing of the intake valve was retarded 30°. Although Atkinson cycle with the retarded cam leads to a low in-cylinder pressure in the compression stroke, the engine work can still be increased by advancing injection timing. On that account, we investigated effect of various operating parameters for reduce emission and fuel consumption, as it could be achieved with low NOx at the same level fuel consumption and PM.