Abstract
HCCI technology has attracted considerable interest over recent years as a means to simultaneously reduce NOx and particulate matter (PM) emissions from diesel engines and to improve NOx emissions and fuel consumption in gasoline engines. Problems regarding controlling HCCI combustion and the limitation of being only able to operate at part loads in gasoline engines, however, raise questions of its economic viability and practical implementation.
The aim of this paper is to address the potential of using combined HCCI and SI technologies in a `mixed mode´ HCCI-SI engine as a way to improve the part load fuel economy and NOx emissions and yet retain full operational performance.
A baseline simulation model of a current production vehicle, with a four-cylinder engine was produced and correlated to measured test data. Experimental results of HCCI investigations have been projected onto the baseline simulation model and fuel consumption analysis performed over the New European Drive Cycle (NEDC) and the Japanese 10-15 mode cycle. The simulation results indicate that the drive-cycle fuel consumption can be reduced by 6 to 8 % and NOx emissions improved by ~ 22% for the vehicle considered over the NEDC cycle and ~ 46 % over the 10-15 mode cycle. Mechanical valvetrain and exhaust system technologies, which enable HCCI operation to be employed on an engine using substantially standard components, are also discussed.
Keywords:HCCI, gasoline, fuel economy improvement, NEDC, Japan 10-15 cycle