Oxidation of Large Molecular Weight Hydrocarbons in a Pressurized Flow Reactor.
Oxidation of Large Molecular Weight Hydrocarbons in a
Pressurized Flow Reactor.
Lenhert, D. B.; Cernansky, N. P.; Miller, D. L.
A4 - Real Fuels/Paper A22;
Combustion Institute/Western States, Central States and
Eastern States. Fourth (4th) Joint Meeting of the U.S.
Sections. Hosted by The Eastern States Section of the
Combustion Institute and Drexel University. A4 - Real
Fuels/Paper A22. March 20-23, 2005, Philadelphia, PA,
1-6 pp, 2005.
combustion; hydrocarbons; molecular weight; ignition;
The preignition behavior of several large molecular
weight hydrocarbons, neat and binary mixtures, has been
examined in a pressurized flow reactor in the low and
intermediate temperature regime (600 - 800 K) at
elevated pressures (8 atm). The hydrocarbons examined
included n-dodecane, 2,2,4,4,6,8,8-heptamethyl-nonane
(iso-cetane), methylcyclohexane, and 1-
methylnaphthalene. For each experiment, gas-phase
samples were extracted to identify and quantify the
major oxidation products. All of the fuels exhibited a
strong negative temperature coefficient (NTC) behavior
at the conditions investigated. The quantification
showed that the majority of the intermediates of
n-dodecane and iso-cetane were fuel fragments less than
half the original fuel size. Methylcyclohexane
dehydrogenated instead of fragmenting. The results were
compared to a lumped mechanism developed by Ranzi and
Faravelli at Politecnico di Milano. For n-dodecane and
iso-cetane, the agreement between the mechanism and
experiments were generally acceptable, but the model
overestimated the formation of lower molecular weight
fragments. The agreement for methylcyclohexane was
considerably worse, as the mechanism improperly assumed
that the fuel fragments instead of dehydrogenates.
Several improvements to the mechanism are suggested
based upon the experimental evidence.