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Novel Diesel combustion concepts such as premixed charge compression ignition (PCCI) and reactivity controlled compression ignition (RCCI) promise lower NOx and PM emissions than those of conventional Diesel combustion. RCCI, which can be implemented using low-reactivity fuels such as gasoline or gases and high-reactivity fuels such as Diesel, has the potential to achieve extremely low emissions and improved thermal efficiency. However, to achieve RCCI combustion, a higher boost pressure than that of a conventional engine is required because a high EGR rate and a lean mixture are necessary to achieve a low combustion temperature. However, higher boost pressures can cause damage to intake systems. In this research, the addition of gaseous fuel to a CI engine is investigated to reduce engine emissions, mainly NOx and PM emissions, with the same IMEP level. Two different methods were evaluated.

The alternative fuel jet propellant 8 (JP-8, NATO F-34) can be used as an auto-ignition source instead of diesel. Because it has a higher volatility than diesel, it provides a better air-fuel premixing condition than a conventional diesel engine, which can be attributed to a reduction in particulate matter (PM). In homogeneous charged compression ignition (HCCI) or dual-fuel premixed charge compression ignition (PCCI) combustion or reactivity controlled compression ignition (RCCI), nitrogen oxides (NOx) can also be reduced by supplying external exhaust gas recirculation (EGR). In this research, the diesel and JP-8 injection strategies under conventional condition and dual-fuel PCCI combustion with and without external EGR was conducted. Two tests of dual-fuel (JP-8 and propane) PCCI were conducted at a low engine speed and load (1,500 rpm/IMEP 0.55 MPa). The first test was performed by advancing the main injection timing from BTDC 5 to 35 CA to obtain the emissions characteristics.