The Description of the Regeneration Behavior of Diesel Particulate Traps with the Aid of a Mathematical Model

Monolithic ceramic filters, suitable for reducing particulate emissions to within the 0,2 g/mile emissions limit, are intermittantly loaded and regenerated. A mathematical model was developed in order to describe the processes which take place in the filter during regeneration. The basis of the calculation model, such as reaction kinetics, heat and mass transfer, energy and mass balance, and flow performance are explained. Filter temperature, soot oxidation and exhaust flow behavior are described over the length of a filter channel.

A calculated and measured regeneration sequence for an engine operating point near engine full load are illustrated and compared. The results show that due to the prevailing higher temperatures, an intensified soot oxidation occurs at the rear of the channel. A comparison of calculated and measured regeneration requirements as well as salient oxidation parameters leads to the definition of an engine operating range where the minimum regeneration requirements are satisfied. In this range the filtered soot mass and the oxidizing soot mass are in equilibrium.