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A data-driven, lumped kinetic modeling of OME2-5 pyrolysis and oxidation

par Dinelli, Timoteo;Pegurri, Alessandro;Bertolino, Andrea ;Parente, Alessandro ;Faravelli, Tiziano;Mehl, Marco;Stagni, Alessandro
Référence Proceedings of the Combustion Institute, 40, 1-4, 105547
Publication Publié, 2024-01

Article révisé par les pairs

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Résumé :

The kinetic mechanisms describing the combustion of longer-chain fuels often have limited applicability due to the high number of species involved in their pyrolysis and oxidation paths. In this work, this is addressed for what concerns oxymethylene ethers (OMEn), which recently emerged as synthetic fuel candidates for diesel applications. Starting from an established mechanism representing the pyrolysis and oxidation of dimethoxymethane DMM or OME1, the combustion chemistry of heavier OMEs up to OME5 was developed by relying on reaction classes, where structural isomers were lumped into pseudospecies, and the related rates assigned according to analogy and rate rules, considering OME1 and its lumped chemistry as reference. The obtained lumped model was then coupled to a data-driven optimization methodology, still based on reaction classes, where the consistency among the OME2-5 submodules was preserved through scaling factors previously defined. Such a combined approach proved particularly effective in delivering a compact kinetic mechanism, requiring only 48 species on top of the OME1 model for its extension up to OME5. The extensive validation and analysis of model predictions show the successful capability of the lumped formulation in representing the chemical behavior of the whole OME family, and the effectiveness of the optimization procedure in further improving model predictions throughout most of the operating space and target properties (ignition delay times in shock tubes, laminar flame speeds, speciations in stirred and flow reactors). The successful implementation of this workflow paves the way for its extensive use for the kinetic modeling of even heavier fuels and its coupling with skeletal reduction techniques to further reduce their size to affordable levels for CFD applications.