Reduction of large detailed chemical kinetic mechanisms for autoignition using joint analyses of reaction rates and sensitivities

Independent technical summary

The study presents a reduction method for detailed autoignition mechanisms that combines reaction-rate analysis with sensitivity analysis to identify reactions that can be removed while retaining the predictive behaviour of the parent mechanism.

The work examines how threshold values used in the two analyses affect the resulting mechanism size, computational efficiency and predictive accuracy. It also develops practical rules for selecting those thresholds and applies the method to detailed mechanisms for two reference hydrocarbons: n-heptane and isooctane.

The reduced mechanisms reproduce ignition-delay times and intermediate-species concentrations from the full mechanisms with good reported accuracy. The article reports calculation speedup factors of 5.9 for the n-heptane mechanism and 16.7 for the isooctane mechanism without a reported loss of accuracy in the target predictions.

Technical contribution

The work addresses a central modelling problem in combustion kinetics: reducing the computational cost of detailed mechanisms while retaining the reactions needed to reproduce selected autoignition observables.

Its principal methodological contribution is the joint use of reaction-rate and sensitivity information rather than reliance on a single reduction criterion. The resulting reduced mechanism remains application-dependent because retained accuracy is defined against the fuels, conditions and target quantities used during reduction and evaluation.

Scope and application boundary

A reduced mechanism should not be assumed to retain equal accuracy outside its tested fuel compositions, temperature and pressure ranges, equivalence ratios, reactor assumptions and target observables.

Application to CFD, engine simulations or new fuels requires independent validation against the intended operating domain, including ignition delay, heat release, major and intermediate species and any pollutant pathways relevant to the new use case.

Publisher access

The Version of Record is available from Wiley through the DOI: access the publisher record . Access may require an institutional or individual subscription.

Citation

Saylam, A., Ribaucour, M., Pitz, W. J., & Minetti, R. (2007). Reduction of large detailed chemical kinetic mechanisms for autoignition using joint analyses of reaction rates and sensitivities. International Journal of Chemical Kinetics, 39(4), 181–196. https://doi.org/10.1002/kin.20232

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