고온흡기를 적용한 예혼합 압축착화 디젤 엔진에서 EGR 율에 따른 엔진효율 및 배기가스 변화

Abstract

The application of early diesel injection for near-homogeneously premixed charge was tested in the single-cylinder engine. HCCI combustion has been investigated with the variety of fuel injection parameters e.g. injection timing, number of injections. In an attempt to control the combustion phase for HCCI operation, low compression ratio with Exhaust Gas Recirculation (EGR) and hot intake temperature has been applied. Compression ratio was applied up to 14.8 and EGR up to 45% to control the combustion phase with 160°C intake air temperature to assist evaporating of diesel fuel. Results showed the early-injection of 120°CA BTDC achieved negligible amount of PM and NOx emissions. The two-stage injection injecting most of the fuel at early timing followed by small amount of near TDC injection provided guidance to increase the power-output. Finally, Optimal EGR rate in high power-output was observed at around 30% due to the trade-off characteristics between combustion efficiency and work conversion efficiency.