1D Modeling of the Hydrodynamics and of the Regeneration Mechanism in Continuous Regenerating Traps

The present work focuses on the simulation of the hydrodynamics, transient filtration/loading and catalytic/NO2-assisted regeneration of Diesel after-treatment systems. A 1D unsteady model for compressible and reacting flows for the numerical simulation of the behavior of Diesel Oxidation Catalysts (DOCs) and Diesel Particulate Filters (DPFs) has been developed. The numerical model is able to keep track of the amount of soot in the flow; the increasing of back-pressure through the exhaust system (mainly due to the Diesel Particulate Filter) can be predicted by the calculation of the permeability variation of the porous wall, as the soot particles goes inside the DPF. A sub-model for the regeneration of the collected soot has been developed: the collected particulate is oxidized by the Oxygen (O2) and by the Nitrogen Dioxide (NO2). The new approach allows to study the devices' behavior under unsteady state operating conditions, when the thermo-fluid dynamic characteristics of the pulsating flow induced by the cylinders are imposed at the inlet section of the exhaust system. The after-treatment system of a 1.9L JTD FIAT turbocharged diesel engine has been modeled. The numerical code has been calibrated and validated by an extensive set of experimental data (filter pressure drop, exhaust temperatures, exhaust mass flow rate and gaseous emissions) provided by Elasis: data were referred to steady state experiments, which covered a wide range of operating conditions. Deposition and regeneration (both thermal and fuel-additive) were predicted satisfactorily.