Optimization of Gasoline Partially Premixed Combustion Mode

Recent works have demonstrated the possibility of operating compression ignition engine with high resistance to auto-ignition fuels as gasoline. By using gasoline and dilution by exhaust gas recirculation, compression ignition can reach high efficiencies and low particulate (PM) and NOx emissions. One of the promising strategies to reach this combustion is the Gasoline Partially Premixed Combustion (GPPC) concept. First step of the study was to optimize the run of a single cylinder Diesel engine in GPPC with double injections strategy by change the second injection phasing and EGR level. The optimum in terms of heat release rate and regulated pollutant emissions was obtained for second injection timing around TDC and an EGR level at 30%. To perform future optical techniques to provide analysis of mixture preparation, a surrogate of Gasoline (mixture of Isooctane, N-heptane and Toluene) was tested: first its capacities to ignite as function of intake temperature, pressure and EGR level variation by using HCCI experiment and second, its capacities to ignite by using single direct injection.