In an effort to understand the effects of injection system pressure on alternative fuel performance, a single-cylinder diesel engine was outfit with a modern common rail fuel injection system and piezoelectric injector. As future new fuels will likely be used in both older mechanical injected engines as well as newer high pressure common rail engines, the question as to the sensitivity of a new fuel type across a range of engines is of concern. In this study, conventional diesel fuel (Navy NATO F76) was compared with the new Navy hydroprocessed renewable diesel (HRD) fuel from algal sources, as well as the high cetane reference fuel nC16 (n-hexadecane CN = 100). It was seen that, in general, ignition delay (IGD) was shortened for all fuels with increasing fuel injection pressure and was shortened with higher CN fuels. The combustion duration for all fuels was also significantly reduced with increasing fuel injection pressure, however, longer durations were seen for higher CN fuels at the same fuel pressure due to less premixing before the start of combustion. Companion modeling using the Lawrence Livermore National Lab (LLNL) heavy hydrocarbon and diesel primary reference fuel (PRF) chemical kinetic mechanisms for HRD and nC16 was applied to understand the relative importance of the physical and chemical delay periods of the IGD. It was seen that at low fuel injection pressures, the physical and chemical delay times are of comparable duration. However, as injection pressure increases the importance of the chemical delay times increases significantly (longer), especially with the lower CN fuel.
The Effects of Fuel Injection Pressure and Fuel Type on the Combustion Characteristics of a Diesel Engine
Contributed by the Combustion and Fuels Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received February 28, 2015; final manuscript received March 1, 2015; published online March 31, 2015. Editor: David Wisler.
This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.
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Cowart, J., Luning Prak, D., and Hamilton, L. (October 1, 2015). "The Effects of Fuel Injection Pressure and Fuel Type on the Combustion Characteristics of a Diesel Engine." ASME. J. Eng. Gas Turbines Power. October 2015; 137(10): 101501. https://doi.org/10.1115/1.4029949
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