Emissions reduction potential of high EGR rates in D.I. Diesel engines

Exhaust gas recirculation is one important measure to achieve the EU 5 and 6 as well as the US Tier 2 Bin 5 emissions legislation. This work was conducted to quantify the EGR rate necessary to reach EU5 or 6 in three operating points representative for the New European Driving Cycle. Injection and atomisation characteristics were determined in a high pressure high temperature combustion chamber and emissions and performance tests were conducted in a single cylinder research engine. The robustness of a combustion system with high EGR rates against their deviations from the nominal value was quantified. Also, the effectiveness of both, rail pressure and boost pressure, to improve EGR compatibility was assessed.