Evaluating the oxidation kinetic parameters of gasoline direct injection soot from thermogravimetric analysis experiments

The abatement of particulate matter in gasoline direct injection (GDI) engines requires the use of particulate filters. In turn, the optimisation of their regeneration is based on a deep knowledge of the soot oxidation behaviour. The determination of the intrinsic kinetic parameters of GDI soot is explored based on thermogravimetric analysis (TGA) and reaction rate modelling. New understanding on the oxidation of GDI soot is provided enabling an accurate prediction in a wide range of temperature and O₂ concentration. Firstly, the dependence of the soot reaction order on the boundary conditions is discussed. The analysis of the Arrhenius equation parameters reveals variable O₂ reaction order. It leads to consider the effect of mass transfer and adsorption (Langmuir and Dubinin-Radushkevich isotherms) as reaction rate limiters. Combined with the soot reaction order approach, the prediction ability of the proposed model is assessed in an extended range of isothermal and non-isothermal TGA experiments.