Abstract
Keywords Diesel engines, Diesel combustion, injection, pollutant emissions.
Abstract
One of the great challenges in meeting future emission restrictions affecting H.D. diesel engines is the simultaneous reduction of NOx and soot emissions, without worsening fuel consumption. Among the different available strategies, the optimization of the injection parameters, combined with the efficient management of intake air and the use of exhaust gas recirculation (EGR), seems to have still a huge potential of improvement.
With the aim to explore the effects of injection pressure, boost pressure, and EGR on soot, NOx, and BSFC, a study was conduced in a diesel engine fitted with a common-rail injection system. The study combined performance and emissions measurements together with heat release law analysis. Tests were done at high load modes from the European Steady state test Cycle (ESC), because approximately 70% of the NOx produced during the ESC emissions test is produced at high load. The results of the studies have been ultimately evaluated by using the parameters object of optimisation. These have been, mainly, NOx and soot emissions and BSFC. Other secondary parameters have been also calculated, and have been employed in the evaluation, at least only to ensure that no excessive limits were surpassed, as in the case of CO emissions.
Results have shown that the targeted emission levels can be attained with EGR and a moderate increase of boost pressure and an important increase in injection pressure.