A New Approach to the Oxidizing Behavior of a Porous Ceramic Diesel Particulate Trap

A model simulating the behavior of the porous ceramic trap was developed. The model is based on the assumption that the pore size of the trap combined with the particle size distribution resulting from the trap oxidising activity defines two areas of trap operation: Ci) accumulation when no pass-through is permitted, and (ii) continuous regeneration when pass-through is permitted.

The mathematical evaluation of the model demonstrates that regeneration depends on the ratio of space-time and oxidation process time constant. As far as the lower regeneration limit is concerned, temperature is the main parameter, while the upper regeneration limit is imposed by the low space-time. These dependencies have been experimentally confirmed for the couple of a light-duty Daimler-Benz engine and a Corning EX 47 trap. The test data at the regeneration limits have been correlated on the basis of the model and for continuous oxidation of particle mass flow. This resulted in a direct derivation of the physical constants of the oxidation process.