The Effect of a Diesel Oxidation Catalyst and a Catalyzed Particulate Filter on Particle Size Distribution from a Heavy Duty Diesel Engine 2006-01-0877

The effect of a Johnson Matthey catalyzed continuously regenerating technology™ (CCRT®) filter on the particle size distribution in the raw exhaust from a 2002 Cummins ISM-2002 heavy duty diesel engine (HDDE) is reported at four loads. A CCRT® (henceforth called DOC-CPF) has a diesel oxidation catalyst (DOC) upstream (UP) of a catalyzed particulate filter (CPF). The particle size data were taken at three locations of UP DOC, downstream (DN) DOC and DN CPF in the raw exhaust in order to study the individual effect of the DOC and the CPF of the DOC-CPF on the particle size distribution. The four loads of 20, 40, 60 and 75% loads at rated speed were chosen for this study. Emissions measurements were made in the raw exhaust chosen to study the effect of nitrogen dioxide and temperature on particulate matter (PM) oxidation in the CPF at different engine conditions, exhaust and carbonaceous particulate matter (CPM) flow rates. This data was used for calibrating the MTU 1-D 2-layer filter model. Further results from these tests are reported in Reference [1]. Results for both particle number and volume concentrations in nuclei and accumulation-mode particles are discussed in this paper. The DOC had a small effect on the particle number and volume concentrations but the CPF or the DOC-CPF reduced the particle number and volume concentrations by two orders of magnitude. The CPF had higher filtration efficiency for accumulation-mode particles while the DOC had similar effect on nuclei and accumulation-mode particles. As expected, the filtration efficiency of the CPF increases with time during the deep bed filtration due to the blocking of the pores in the wall and is nearly constant for later times during the cake filtration period.