Kinetic model reduction using integer and semi-infinite programming

In this work an optimization-based approach to kinetic model reduction was studied with a view to generating reduced-model libaries for reacting-flow simulations. A linear integer formulation of the reaction elimination problem was developed in order to allow the model reduction problem to be solved cheaply and robustly to guaranteed global optimality. When compared with three other conventional reaction-elimination methods, only the integer-programming approach consistently identified the smallest reduced model which satisfies user-specified accuracy criteria. The proposed reaction elimination formulation was solved to generate model libraries for both, homogeneous combustion systems, and 2-D laminar flames. Good agreement was observed between the reaction trajectories predicted by the full mechanism and the reduced model library. For kinetic mechanisms having many more reactions than species, the computational speedup associated with reaction elimination was found to scale linearly with the size of the derived reduced model. Speedup factors of 4-90 were obtained for a variety of different mechanisms and reaction conditions. The integer-programming based reduction approach was tested successfully on large-scale mechanisms comprising up to [approximately] 2500 reactions. The problem of identifying optimal (maximum) ranges of validity for point-reduced kinetic models was also investigated. A number of different formulations for the range problem were proposed, all of which were shown to be variants of a standard semi-infinite program (SIP). Conventional algorithms for nonlinear semi-infinite programs are essentially all lower-bounding methods which cannot guarantee the feasibility of an incumbent at finite termination.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Bhattacharjee, Binita, 1976-

Advisor dc:contributor.advisor

• Paul I. Barton and William H. Green.

• 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/1721.1/30062

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30062