Experimental Study Comparing Particle Size and Mass Concentration Data for a Cracked and Un-Cracked Diesel Particulate Filter

Steady state loading characterization experiments were conducted at three different engine load conditions and rated speed on the cracked catalyzed particulate filter (CPF). The experiments were performed using a 10.8 L 2002 Cummins ISM-330 heavy duty diesel engine. The CPF underwent a ring off failure, commonly seen in particulate filters, due to high radial and axial temperature gradients. The filters were cracked during baking in an oven which was done to regenerate PM collected after every loading characterization experiment. Two different configurations i.e. with and without a diesel oxidation catalyst (DOC) upstream of the CPF were studied. The data were compared with that on an un-cracked CPF at similar engine conditions and configurations. Pressure drop, transient filtration efficiency by particle size and PM mass and gaseous emissions measurements were made during each experiment. Mass balance for the PM from the engine during the experiments was conducted in order to calculate the mass of PM oxidized.

The pressure drop for the cracked filter was lower by 1 to 8 kPa than that for the un-cracked filter during loading characterization experiments. This was due to low PM accumulation in the cracked filter as compared to the un-cracked filter. Filtration efficiency of the after treatment system was measured based on both number/volume and mass. The filtration efficiency was between 50 and 90% for a cracked filter while that for the un-cracked filter was above 99%. The crack in the CPF did not have any affect on the gaseous emission data.