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In this study, the combustion and emissions characteristics of n-butanol/GTL and n-butanol/ultra-low sulfur diesel (ULSD) blends are compared in a single-cylinder experimental diesel engine. The n-butanol was blended with a Fischer-Tropsch (FT) gas-to-liquid (GTL) fuel, at 25% and 50% mass. N-butanol was also blended with ULSD at the same mass ratios. FT fuels are an attractive alternative to petroleum based fuels because they can be used as a drop-in fuel with existing infrastructure. N-butanol is renewable fuel capable of being produced from waste biomass sources. The investigations were conducted at 1500 rpm and three loads of 2.75, 4.75, and 6.75 IMEP, representative for the research engine. 15% exhaust gas recirculation was utilized along with a supercharger to increase the intake pressure to 1.2 bar absolute. Neat ULSD and GTL, respectively, were investigated as a baseline.

In this study, Premixed Charge Compression Ignition (PCCI) was investigated with alternative fuels, S8 and n-butanol. The S8 fuel is a Fischer Tropsch (FT) synthetic paraffinic kerosene (SPK) produced from natural gas. PCCI was achieved with a dual-fuel combustion incorporating 65% (by mass) port fuel injection (PFI) of n-butanol and 35% (by mass) direct injection (DI) of S8 with 35% exhaust gas recirculation. The experiments were conducted at 1500 rpm and varied loads of 1-5 bar brake mean effective pressure (BMEP). The PCCI tests were compared to an ultra-low sulfur diesel no. 2 (ULSD#2) baseline in order to determine how the alternative fuels effects combustion, emissions, and efficiencies. At 3 and 5 bar BMEP, the heat release in the PCCI mode exhibited two regions of high temperature heat release, one occurring near top dead center (TDC) and corresponds to the ignition of S8 (CN 62), and a second stage occurring ATDC from n-butanol combustion (CN 28).