NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Oxidation of Large Molecular Weight Hydrocarbons in a Pressurized Flow Reactor.


pdf icon Oxidation of Large Molecular Weight Hydrocarbons in a Pressurized Flow Reactor. (286 K)
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.

Keywords:

combustion; hydrocarbons; molecular weight; ignition; oxidation; temperature

Abstract:

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.