Detailed Diesel Exhaust Particulate Characterization and Real Time DPF Filtration Efficiency and Regeneration Measurements

David  Foster, University of Wisconsin – Madison

A single cylinder Cummins N14 research engine, with a high pressure unit injector, has been operated over a range of loads and speeds. Detailed exhaust measurements of the gaseous and particulate matter have been made for exhaust configurations with and with out a diesel oxidation catalyst. The exhaust instrumentation included simultaneous measurements with an FTIR for gas phase species, and a TEOM, an SMPS, a MEXA 1230 real time particle analyzer, a real time Engine Exhaust Particle Sizer (EEPS), and a Teflon and Quart fiber filter system, for detailed characterization of the particulate matter in the exhaust. The particulate matter and gaseous species have been characterized for several engine operating conditions with and without the diesel oxidation catalyst in place. With these data as a baseline, the processes occurring in a diesel particulate filter (DPF) were investigated through real time measurement of the mass and size distributions downstream of the particulate filter for filling and regeneration sequences.

The data indicate that the change in pressure drop across the DPF and its relationship to the mass of particulate matter in the trap depends not only on the particulate concentration and the volumetric flow rate of the exhaust but also the chemical partitioning of the particulate matter between elemental and organic carbon. The real time measurements in the exiting flow of the DPF show how the filtration efficiency changes as the trap fills, and how using a burner in the exhaust stream for in-situ regeneration impacts the filtration efficiency during regeneration.

These data have been acquired for different cordierite filters: catalyzed, wash coated only and bare, and for a catalyzed SiC filter. These data as well as an overview of futer work will be offered for discussion.