Reduction in Harmful Emissions Using a Two-Stage Injection-Type Premixed Charge Compression Ignition Engine

Abstract

As world attention has focused on global warming and air pollution, high-efficiency diesel engines with low carbon dioxide (CO2) emissions have become more attractive. Premixed charge compression ignition (PCCI) diesel engines in particular have the potential to achieve a more homogeneous mixture in the cylinder, which results in lower nitrogen oxide (NOx) and soot emissions. In this study, it was investigated how a split injection strategy affected the combustion and emissions characteristics of a four-cylinder PCCI engine in terms of injection timing and fuel mass fraction ratio. In addition, this article presents the effects of engine operation conditions [e. g., cooled: exhaust gas recirculation (EGR) rate, intake pressure, and swirl ratio] on exhaust emissions and fuel consumption. Experimental results show that the optimum injection timing for the split injection mode are an early injection at after drop dead center (ATDC)-60 degrees and a main injection at ATDC5 degrees. It was also found that the EGR rate and swirl ratio both exert a significant influence on the combustion and emission performance of the four-cylinder PCCI engine.