Impact of Military JP-8 Fuel on Heavy Duty Diesel Engine Performance and Emissions.

摘要

The US army single fuel forward policy mandates that deployed vehicles must refuel with aviation fuel JP-8, and when that is not available, are permitted to use diesel. The US army is expected to use JP-8 till year 2025. There is a known torque and fuel economy penalty associated with the operation of a diesel engine with JP-8 fuel due to its lower density and viscosity, but few experimental studies suggest that kerosene-based fuels have the potential for lowering exhaust emissions (especially particulate matter) compared to typical distillate fuels such as diesel no. 2. However, studies so far were typically focused on quantifying effects of simply replacing the regular diesel fuel with JP-8, rather than fully investigating the reasons behind the observed differences. This research evaluates the effect of using JP-8 fuel in a heavy duty diesel engine on fuel injection, combustion, performance and emissions, and subsequently utilizes the obtained insight to propose engine calibration capable of minimizing the possible penalties. Test experiments were carried out on a Detroit Diesel Corporation (DDC) S60 engine outfitted with EGR. The results indicate that torque and fuel economy of diesel fuel can be matched without smoke or NOx penalty by increasing the duration of injection to compensate for lower density. The lower cetane number of JP-8 led to higher ignition delay and increased premixed combustion, but adjusting of injection timing to keep the ignition timing unchanged had a minor effect. Under almost all conditions, JP-8 led to lower NOx and PM emissions and shifted the NOx-PM tradeoff favorably.