ef0c00094_si_001.pdf (113.24 kB)
Impact of Biofuel Blends on Black Carbon Emissions from a Gas Turbine Engine
journal contribution
posted on 2020-03-31, 19:46 authored by Raju R. Kumal, Jiawei Liu, Akshay Gharpure, Randy L. Vander Wal, John S. Kinsey, Bob Giannelli, Jeffrey Stevens, Cullen Leggett, Robert Howard, Mary Forde, Alla Zelenyuk, Kaitlyn Suski, Greg Payne, Julien Manin, William Bachalo, Richard Frazee, Timothy B. Onasch, Andrew Freedman, David B. Kittelson, Jacob J. SwansonPresented
here is an overview of nonvolatile particulate matter
(nvPM) emissions, i.e., “soot”, as assessed by TEM analyses
of samples collected after the exhaust of a J-85 turbojet fueled with
Jet-A as well as with blends of Jet-A and Camelina biofuel. A unifying
explanation is provided to illustrate the combustion dynamics of biofuel
and Jet-A fuel. The variations of primary particle size, aggregate
size, and nanostructure are analyzed as a function of biofuel blend
across a range of engine thrust levels. The postulate is based on
where fuels start along the soot formation pathway. Increasing biofuel
content lowers aromatic concentration while placing increasing dependence
upon fuel pyrolysis reactions to form the requisite concentration
of aromatics for particle inception and growth. The required “kinetic”
time for pyrolysis reactions to produce benzene and multiring PAHs
allows increased fuel–air mixing by turbulence, diluting the
fuel-rich soot-forming regions, effectively lowering their equivalence
ratio. With a lower precursor concentration, particle inception is
slowed, the resulting concentration of primary particles is lowered,
and smaller aggregates were measured. The lower equivalence ratio
also results in smaller primary particles because of the lower concentration
of growth species.