An Experimental Study of Dual Fueling with Gasoline Port Injection in a Single-Cylinder, Air-Cooled HSDI Diesel Generator

An experimental study was conducted on an air cooled high-speed, direct-injection diesel generator that investigated the use of gasoline in a dual fuel PCCI strategy. The single-speed generator used in the study has an effective compression ratio of 17 and runs at 3600 rev/min. Varying amounts of gasoline were introduced into the combustion chamber through a port injection system. The generator uses an all-mechanical diesel fuel injection system that has a fixed injection timing. The experiments explored variable intake temperatures and fuel split quantities to investigate different combustion phasing regimes.

Results from the study showed low combustion efficiency at low load. Low load operation was also characterized by high levels of HC and CO (in excess of 20 g/kwh and 50 g/kwh respectively). Operation at 75% load was more efficient, and displayed three different combustion regimes that are possible with PIG (port injected gasoline) dual fuel PCCI. At full load, PIG operation provided vast improvements in the emissions of soot. The reduction of soot was likely the result of improvements in fuel mixture homogeneity leading to lower local equivalence ratios. Gasoline was also found to both delay and advance the ignition timing, depending on the fueling rates and intake temperatures.