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Chemical Kinetics Laboratory Institute of Chemistry
ELTE Eötvös Loránd University
Address: 1117 Budapest Pázmány Péter sétány 1/A, Hungary
phone: +36-1-372-2500
room 145     extension 1108
room 146     extension 1109
room 147     extension 1201
room 153     extension 1909
room 118     extension 1047
fax: +36-1-372-2592
e-mail: turanyi@chem.elte.hu
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Our newest publication
Efficient numerical methods for the optimization of large kinetic reaction mechanisms


Optimization of detailed combustion mechanisms means that the corresponding kinetic model is fitted to experimental data via optimizing their important rate and thermodynamic parameters within their domain of uncertainty. Typically, several dozen parameters are fitted to several hundred to several thousand data points. Many numerical optimization methods have been used, but the efficiency of these methods has not been compared systematically. In this work, parameters of a H2/O2/NOx mechanism (214 reaction steps of 35 species) were fitted to 1552 indirect (ignition delay times measured in shock tubes and concentrations measured in flow reactors) and 755 direct measurements. Three test cases were investigated: (1) fitting the Arrhenius parameters of 2 reaction steps to 732 data points; (2) fitting the Arrhenius parameters of 4 reaction steps to 1077 data points; (3) fitting the Arrhenius parameters of 10 reaction steps to 2307 data points. All three cases were investigated in two ways: fitting the A-parameters only and fitting all Arrhenius parameters (5, 11 and 29 parameters, respectively). A series of global (FOCTOPUS, genetic algorithm, simulated annealing, particle swarm optimization, covariance matrix adaptation evolutionary strategy (CMA-ES)) and local (simplex, pattern search, interior-point, quasi-Newton, BOBYQA, NEWUOA) optimization methods were tested on these cases, some of them in two variants. The methods were compared in terms of the final error function value and number of error function evaluations. The main conclusions are that the FOCTOPUS resulted in the lowest final error value in all cases, but this method required relatively many error function evaluations. As the task became more difficult, more and more methods failed. A variant of the BOBYQA method looked stable and efficient in all cases.
 
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Our central computer code
Optima++

Optima++ is a general framework for manipulating experimental data related to combustion chemistry, carrying out simulations of such experiments, performing model optimization and analysis, and providing auxiliary features for the above tasks. Optima++ is able to handle simulation codes FlameMaster, OpenSMOKE++ and ZeroRK. Also, Cantera is coming soon.

An interactive web site, where the users may find Arrhenius parameters of gas phase elementary reactions determined in direct measurements, theoretical calculations or have been used in modelling studies. The users may recalculate the uncertainty limits of the rate coefficients. The editors have the right to upload data sheets for new reactions and to add, delete or modify existing data sheets. The editor status may be granted to any registered user upon request to the administrator.

Visit k-evaluation web page

Reaction fluxes of a combustion simulation can be visualized in the forms of still pictures and videos.


Available from ReSpecTh.hu

We maintain a collection of a series of  Chemkin-format reaction mechanisms for the combustion of the following fuels:
hydrogen, syngas, methanol, ethanol, methane, butanol, fuels+NOx.


Available from ReSpecTh.hu

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