Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-II-8MODELING OF DIESEL FILTERS FOR PARTICULATE REMOVALMatyáš Schejbal a , Petr Kočí a , Milan Kubíček b , Miloš Marek aa Department of Chemical Engineering, Institute of Chemical Technology PragueFax: +420 220 444 320, e-mail: matyas.schejbal@vscht.cz, http://www.vscht.cz/monolithb Department of Mathematics, Institute of Chemical Technology PragueTechnická 5, 166 28 Prague 6 – Dejvice, Czech RepublicA diesel particulate filter(DPF) is regarded as the most hopeful technology to reduceparticulate matter or soot from exhaust gas of a diesel engine with filtration efficienciesfrequently excessing 90%. It is constructed from a square cell monolith structure and thechannels are plugged at alternate ends. Exhaust gas entering the channel is forced to exitthrough the ceramic porous wall into the adjoining cells and thus leaving behind theparticulates. The collected particulate matter inside the trap has to be periodically oxidized toreduce the pressure drop. The burning of the collected particle matter inside the traprepresents DPF regeneration. The deposition of particles and the regeneration of filters aresubject of modeling. We have developed an advanced mathematical nonstationary spatially2D model of the filter and its regeneration. The momentum, mass and enthalpy balances ofthe gas and the solid phase were employed in the model including the description of heatconduction, diffusion in the solid phase and complex soot combustion kinetics. Thedescription of kinetics of two types of combustion by O 2 – both the thermal initiated one andthe catalyzed one (e.g. Ce oxides based catalyst is added to the fuel) and the oxidation by NO 2is used in the reaction-diffusion equations for each gaseous component. The results ofsimulations include the prediction of development of concentrations, temperature, pressureand flow pattern, soot layer thickness along the filter. Contribution presents parametricstudies, simulations review and detailed discussion of the kinetics of NO 2 -assisted sootoxidation coupled with NO/NO 2 equilibrium reaction and also a filtration model. Thefiltration model includes cake and deep-bed filtrations and thus predicts porosity,permeability, filtration efficiency of the soot layer and the wall. Main advantage of thedeveloped numerical model for simulations is fast computing of both the regeneration processand the DPF loading. Software for the solution of the above mentioned models will bedescribed and results for various operation conditions will be presented.89