Effects of Low Temperature Premixed Combustion (LTPC) on Emissions of a Modern Diesel Engine for Passenger Cars 2010-01-0333

In this paper, a Low Temperature Premixed Combustion (LTPC) was investigated employing a four cylinder D.I. common rail Diesel engine, used for passenger cars on the European market. Experiments were carried out setting the engine speed at 2500 rpm with a fuel amount of 26 mg/str to realize an operating condition close to the point of NEDC at 0.8 MPa of BMEP. The experimental approach was the management of the start of injection, injection pressure and EGR rates as a method to control NOx and soot production. The investigation was first carried out testing engine performances and emissions as set from the commercial engine map. Afterward, engine tests were carried out exploring performances, gaseous and smoke emissions at late start of combustion [10 to 17.5 cad ATDC], injection pressures from 80 to 120 MPa and EGR rates up to 50%.

The management of injection timing coupled to increased injection pressures and moderate levels of EGR allowed to get a partial homogenization of the in-cylinder mixture with the production of lower NOx, HC and soot emissions compared to the existing engine map, with minor penalties on engine performances.