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"The Single Fuel Forward Policy" legislation enacted in the United States mandates that deployed U.S. military ground vehicles must be operable with aviation fuel (JP-8). This substitution of JP-8 for diesel raises concerns about the compatibility of this fuel with existing reciprocating piston engine systems. This study investigates the combustion, emissions, and performance characteristics of blends of JP-8 and Ultra Low Sulfur Diesel (ULSD) fuels with similar cetane numbers (CN), 48 (JP-8) and 47(ULSD), respectively, in a direct injection (DI) compression ignition engine over the load range of 3-8 bar imep at 1400 rpm. The results showed that JP-8 blends and ULSD had ignition delays ranging from approximately 1.0-1.4 ms and an average combustion duration time in the range of 47-65 CAD. Cylinder maximum heat flux values were found to be between 2.0 and 4.4 MW/m₂, with radiation flux increasing much faster than convection flux while increasing the imep.

In this study, a direct injection (DI) compression ignition engine fueled with biodiesel was supplemented with n-butanol port fuel injection (PFI) in order to simultaneously reduce in cylinder nitrogen oxides formation, decrease soot and favorable modify their trade-off. The combustion and emission characteristics were investigated for regimes of 1-5 bars IMEP at 1400 rpm. By applying this methodology, for the regimes in which the n-butanol PFI was applied, the premixed charge combustion has been split into two regions of high temperature heat release, an early one, BTDC, and a second stage ATDC, oxidizing the soot formed from biodiesel combustion and therefore modifying favorable the soot-NOx trade-off. With n-butanol injection, the soot emissions showed a significant decrease as much as 90%, concomitantly with a 50% NOx reduction at higher PFI rates. Non-regulated emissions measurements showed increases in acetaldehyde with n-butanol PFI.

This study evaluates the combustion and emissions characteristics of methyl oleate (C₁₉H₃₆O₂ CAS# 112-62) produced by transesterification from oleic acid, one of the main fatty acid components of biodiesel. The ignition delay of ultra-low sulfur diesel#2 (ULSD) and its blends with methyl oleate (O20-O50), varied between 6.5-9.7 CAD, depending on speed, at constant load of 8 bar imep (100% load). The CN was 47 for ULSD and increased up to 51 for O50, which resulted in the start of combustion's premixed phase being advanced by about 2 CAD while reducing the maximum apparent heat release of about 30%. The combustion duration varied in the range of about 56-67 CAD and the maximum total heat flux rate, presented values from 4.2 to 5.5 MW/m₂, which correlate well with the increase of the convection flux because of the speed increase. The maximum cycle temperature was in the range of 2500K for the speeds from 1200 to 1800 rpm for both fuels.