Simulating the impact of premixed charge compression ignition on light-duty diesel fuel economy and emissions of particulates and NO_x

We report results from urban drive cycle simulations of a light-duty conventional vehicle and a similar hybrid electric vehicle, both of which are equipped with diesel engines capable of operating in either conventional diesel combustion mode or in premixed charge compression ignition mode. Both simulated vehicles include lean exhaust after-treatment trains for controlling hydrocarbon, carbon monoxide, nitrogen oxide, and particulate matter emissions. Our results indicate that, in the simulated conventional vehicle, premixed charge compression ignition can significantly reduce fuel consumption and emissions by reducing the need for lean nitrogen oxide traps and diesel particulate filter regeneration. However, the opportunity for utilizing premixed charge compression ignition in the simulated hybrid electric vehicle is limited because the engine typically experiences higher loads and multiple stop-start transients that are outside the allowable premixed charge compression ignition operating range. This suggests that developing ways of extending the premixed charge compression ignition operating range combined with improved control strategies for engine and emissions control management will be especially important for realizing the potential benefits of premixed charge compression ignition in hybrid electric vehicles.