EXPERIMENTAL EVALUATION OF APPARENT SOOT OXIDATION RATES IN DIESEL PARTICULATE FILTERS

The rate expressions used by different researchers to model the oxidation of soot in diesel filters vary considerably, apparently due to different soot properties between different studies, as well as the inherent difficulties in sampling and measuring the reaction rate in a realistic way. In this work, an attempt is made to overcome the above-mentioned problems in real engine measurements with the combined use of mathematical modelling. The methodology relies on a calculation procedure for the on-line assessment of soot mass in the filter, based on pressure drop modelling. Specially designed experimental protocols are employed to study the reaction rate of soot under various operating conditions and filter loadings. Both uncatalysed and Ce-catalysed soot is tested. Moreover, the soot oxidation with NO2 facilitated by an upstream oxidation catalyst is also studied. The results are suitably processed towards deriving Arrhenius plots and assessing the respective kinetic parameters. The activation energies determined fall within the range of values reported in the literature.

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