Developing fundamentally based models for autoignition

There is renewed interest in autoignition, especially due to the recent development of the homogenous charge compression ignition (HCCI) engine, highly promising with its low Nox and particulate emissions and high efficiency. However it is difficult to control HCCI autoignition. In general accurate prediction of the autoignition behavior of fuel/air mixtures has been difficult, due to inadequate knowledge of low temperature (< 1000K) oxidation. The reactions of peroxy radical RO₂ are hydroperoxyalkyl radical .QOOH are especially problematic. In the first part of this thesis we compute rate parameters for three important reaction pathways from the .QOOH: .QOOH cyclization to form cyclic ether and .OH, .OH migration in .QOOH, and [beta]-scission of [gamma].QOOH. These reactions are competitive with the main chain branching pathway, so their rate constants affect the ignition timing of the system. There are no direct measurement experimental results available for these reactions. We used quantum chemistry, mainly the complete-basis-set extrapolation (CBS-QB3), and calculated the rate constants using the well-known transition state theory (TST). The effects of substituent, nature of radical center, and ring size were also studied. Generalized rate estimation rules for these reactions were derived for later use in automated generation of oxidation mechanisms. The second part of this thesis reports the construction of a rate rules library and rate rules trees for the major reaction families in combustion, useful for automated generation of reaction mechanisms. A detailed oxidation mechanism consists of thousands of reactions, and building such a large mechanism is a laborious task if done manually by hand.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Chemical Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Wijaya, Catherina D. (Catherina Dewi)

Advisor dc:contributor.advisor

• W.H. Green, Jr.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/32326

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/32326