Implementation of the Partially Premixed Combustion concept in a 2-stroke HSDI diesel engine fueled with gasoline

An experimental investigation has been performed to evaluate the potential of the PPC concept for pollutant control, using a commercial gasoline with Research Octane Number of 95 in a newly-designed 2-stroke poppet valves automotive diesel engine. The experimental results confirm how it is possible to achieve stable gasoline PPC combustion at a low speed medium load point (1200 rpm, 5 bar IMEP); with good combustion stability (σIMEP below 3%), high combustion efficiency (over 98%), and low NOX and zero soot levels; thanks to the wide control of the cylinder gas temperature provided by the air management settings. Nevertheless, in agreement to the results reported in the literature, the indicated cycle efficiency attained at this low load operating condition is lower than the obtained in conventional diesel combustion conditions. Therefore, a dedicated optimization process of the engine hardware and engine settings is required to fully exploit the benefits of gasoline PPC concept in the investigated 2-stroke engine architecture.