Effects of Compression Ratio on Characteristics of PCCI Diesel Combustion with a Hollow Cone Spray

Characteristics of premixed charge compression ignition (PCCI) Diesel combustion were investigated experimentally. In a PCCI engine, the operatable range is limited by the cyclic variation at low loads and the intensive knock at high loads. In the present study, effects of compression ratio on the characteristics of the PCCI combustion are investigated experimentally. The compression ratio was varied from 18.8 to 14.8. For the early injection timing, the high load operation limit is extended from BMEP = 0.22 MPa to 0.40 MPa. At the same time, the minimum BSFC for the early injection timing decreases from 330 g/kWh to 230 g/kWh.