대형 디젤 엔진에서 복수의 분사기를 이용한 동시분사 전략이 압축착화 연소 및 배기 배출물에 미치는 영향

Diesel engines are popular worldwide in commercial vehicles due to their superior efficiency, high durability and good reliability. However, the diesel engine suffers from relative high nitrogen oxide (NOx) and particulate matter (PM) emissions, as the emission regulations are becoming more stringent year by year. Homogeneous Charge Compression Ignition (HCCI) concept is a promising technique in diesel engines to satisfy stringent future emission without much impact on fuel economy. The NOx and PM formations are avoided due to lack of fuel-rich and high temperature region. However, a fuel wallfilm, which was formed on the surface of the piston squish area and cylinder liner, caused increases in HC (hydrocarbon) and CO (carbon monoxide) emission. The effect of simultaneous injection strategy using two injectors located in the center and side of cylinder was conducted as a method to minimize this problems. In a case of side injector alone, characteristic of combustion and emission were much different from center located injector case. It shows higher combustion efficiency at a HCCI combustion region but combustion stability was dramatically decreased. When it comes to simultaneous injection strategy, a large amount of hydrocarbon and carbon monoxide were produced than single injector case although higher heat release was obtained. This might be contributed by formation of large fuel droplet during fuel collision process rather than fuel atomization improvement.