• Dr. Frederick Dryer
  • Princeton University
  • 316 Randolph Hall
  • 11:00 a.m.
  • Faculty Host: Dr. Rakesh Kapania

The transportation energy sector, especially for aircraft, depends upon the use of liquid hydrocarbon fuels, principally because of their high energy density per unit volume, and air transportation is forecast to grow more rapidly than residential, industrial, and electric power sectors over this century. Energy security and global climate implications are major drivers for energy conservation, and the offset of fossil energy use by renewable fuel strategies. Reducing net carbon cycle and air pollutant emissions associated with air transportation is typically considered to be more difficult than for other energy sectors. Today, transportation is fueled principally by petroleum derived liquids, so efforts that are integrated appropriately with present fuel production, distribution, storage, and the current immense investment in legacy hardware are critical to achieving long term address of the economic and climate change drivers as well as to reducing our dependence on foreign oil imports. This presentation will discuss the complex nature of the transportation energy sector, particularly that for aircraft. We will consider the physical and chemical properties of real transportation fuels derived from petroleum, the present certification methods that designate fuels as fit-for-use as aircraft fuels, and how these issues impact the integration of new alternative fuels derived from non-petroleum resources.

The fact that all transportation fuels (jet aviation, diesel and gasoline) are complex mixtures of hundreds of chemical components of generally unknown molecular composition presents a significant challenge to formulating methodologies that characterize detailed, fuel-specific combustion/emissions responses to specific fuel properties. A formulation strategy using “surrogate fuel mixtures” that emulate well the fully vaporized global combustion behavior of a specific real jet fuel will be discussed and demonstrated. Surrogate mixtures and real fuel are shown to produce essentially the same fully prevaporized combustion properties provided that both materials share similar derived cetane number (DCN), hydrogen/carbon molar ratio (H/C), threshold sooting index (TSI) and average molecular weight (Mwave). The fundamental bases for this result will discussed and their relevance to the study multi-phase combustion phenomena and the relative importance of physical and chemical kinetic property emulations on applied combustion observations will be described. Implications to constructing robust chemical kinetic models for real fuel combustion predictions will also be described. Extension of findings to ground transportation fuels will also be discussed.