Influence of Jet Fuel Composition on Aircraft Engine Emissions: A Synthesis of Aerosol Emissions Data from the NASA APEX, AAFEX, and ACCESS Missions

We
statistically analyze the impact of jet fuel properties on aerosols
emitted by the NASA Douglas DC-8 (Tail No. N817NA) CFM56-2-C1 engines
burning 15 different aviation fuels. Data were collected for this
single engine type during four different, comprehensive ground tests
conducted over the past decade, which allow us to clearly link changes
in aerosol emissions to fuel compositional changes. It is found that
the fuel aromatic and sulfur content most affect the volatile aerosol
fraction, which dominates the variability (but not necessarily the
magnitude) of the number and volume emissions indices (EIs) over all
engine powers. Meanwhile, the naphthalenic content of the fuel determines
the magnitude of the nonvolatile number and volume EI as well as the
black carbon mass EI. Linear regression coefficients are reported
for each aerosol EI in terms of these properties, engine fuel flow
rate, and ambient temperature and show that reducing both fuel sulfur
content and naphthalenes to near-zero levels would result in roughly
a 10-fold decrease in aerosol number emitted per kilogram of fuel
burned. This work informs future efforts to model aircraft emissions
changes as the aviation fleet gradually begins to transition toward
low-aromatic, low-sulfur alternative jet fuels from biobased or Fischer–Tropsch
production pathways.