PCCI Operation with Fuel Injection Timing Set Close to TDC 2006-01-0920
In order to further reduce exhaust gas emissions, an investigation was carried out with premixed charge compression ignition (PCCI) combustion mode using conventional diesel fuel.
Past research was carried out with early injection into shallow-dish piston bowl, combined with a narrow nozzle angle setting. Early injection significantly reduced NOX emissions, but some of the fuel spray adhered to the piston bowl surface creating a fuel wall-film which was a major cause in increasing soot, HC and CO emissions and fuel consumption .
As a possible solution to this issue, PCCI combustion mode operation on a direct injection diesel engine was investigated with fuel injection timing set close to top dead center (TDC).
As a result, regardless of the fuel injection timing, increasing EGR reduced NOx emissions. In terms of fuel consumption, soot, HC and CO, however, fuel injection timing close to TDC was superior to earlier injection, due to the reduction in the fuel wall-film formation.
Also, the modified re-entrant type configuration (, combined with a conventional nozzle angle setting) provided better performance on both PCCI combustion operation mode and diffusive combustion operation mode in terms of exhaust gas characteristics and fuel economy, combustion stability.