CATEGORY: ETHANOL
SAE Int. J. Fuels Lubr. 6(1):2013, doi:10.4271/2013-01-0888
The
Impact of Low Octane Hydrocarbon Blending Streams on the Knock Limit of “E85”
James P. Szybist and Brian H. West
Oak Ridge National Laboratory
Abstract
An
engine which is optimized to take advantage ethanol’s high octane number and
high latent heat of vaporization experiences increased efficiency and power
through higher compression ratio, direct fuel injection, higher levels of
boost, and a reduced need for enrichment to mitigate knock or protect the
engine and aftertreatment system from overheating.
The ASTM D5798 specification for high level ethanol blends (E85) was
extensively revised in 2011. The minimum ethanol content was revised downward
from 68 vol% to 51 vol%. This, in combination with the use of low octane
blending streams like natural gasoline introduces the possibility of a lower
octane E85 fuel.
Researchers studied whether engines can still be aggressively optimized for the
resultant fuel from the revised ASTM D5798 specification. Study results
revealed that nearly all ethanol-containing fuels are more resistant to engine
knock than UTG-96. This enables ethanol blends made with low octane number
hydrocarbons to be operated at significantly more advanced combustion phasing
for higher efficiency, as well as at higher engine loads.
Free Full Text Source: http://info.ornl.gov/sites/publications/files/Pub39991.pdf
No comments:
Post a Comment