Effects of Two Pilot Injection on Combustion and Emissions in a PCCI Diesel Engine

The effects of two pilot injections on combustion and emissions were evaluated in a single−cylinder turbocharged diesel engine, which operated premixed charge compression ignition (PCCI) modes with multiple heavy exhaust gas recirculation under the low load by experiments simulation. It was revealed that delay start first injection (SOI−P1) or advance second (SOI−P2), respectively, pressure, heat release rate (HRR), temperature peak all increased. Analysis process indicates that, during periods, timing mainly determined SOI−P2 while released influenced SOI−P1. With SOI−P1 SOI−P2, nitrogen oxide (NOx) generation increased significantly soot varied little. In addition, increasing Q1 decreasing quantity (Q2) can manipulate NOx at level. 5 °CA couple reducing Q2 proposed, mitigate compromise between thermal efficiency present PCCI mode.