Investigation of fuel injection strategies on a low emission heavy-duty diesel engine with high EGR rates

摘要

A test programme has been carried out to investigate fuel injection strategies on a single cylinder heavy-duty diesel engine. The programme was designed to use high rates of cooled Exhaust Gas Recirculation (EGR) to control NOx to below 1.0 g/kWh. A novel, flexible fuel injection system capable of up to 250 MPa maximum injection pressure was employed to explore the optimum trade-offs between NOx, soot emissions and fuel consumption. This paper addresses the potential of the system to control emissions using pilot and post injection. Post injections were found to reduce soot emissions at half load by a factor of two or more. With early pilot injection the soot-NO_x trade-off was improved at 25% load but with the drawbacks of high emissions of CO and fuel dilution of oil.