An experimental investigation of fuel reactivity controlled PCCI combustion in a heavy-duty engine

This study investigates the potential of controlling premixed charge compression ignition (PCCI) combustion strategies by varying fuel reactivity. In-cylinder fuel blending using port fuel injection of gasoline and early cycle, direct-injection of diesel fuel was used for combustion phasing control at a medium engine load of 9 bar net IMEP and was also found to be effective to prevent excessive rates of pressure rise. Parameters used in the experiments were guided from the KIVA-CHEMKIN code with a reduced primary reference fuel (PRF) mechanism including injection timings, fuel percentages, and intake valve closing (IVC) timings for dual-fuel PCCI combustion. The engine experiments were conducted with a conventional common rail injector (i.e., wide angle and large nozzle hole) and demonstrated control and versatility of dual-fuel PCCI combustion with the proper fuel blend, SOI and IVC timings. For example, at the 9 bar operating point, NOx and soot were 0.012 g/kW-hr and 0.008 g/kW-hr, respectively. That is, US EPA 2010 heavy-duty NOx and PM emissions regulations are easily met without after-treatment, while achieving 53% net indicated thermal efficiency.