An Experimental Study of Active Regeneration of an Advanced Catalyzed Particulate Filter by Diesel Fuel Injection Upstream of an Oxidation Catalyst

摘要

Passive regeneration (oxidation of particulate matter without using an external energy source) of particulate filters in combination with active regeneration is necessary for low-load engine operating conditions. For low-load conditions, the exhaust gas temperatures are less than 250°C and the PM oxidation rate due to passive regeneration is less than the PM accumulation rate. The objective of this research was to experimentally investigate active regeneration of a catalyzed particulate filter (CPF) using diesel fuel injection in the exhaust gas after the turbocharger and before a diesel oxidation catalyst (DOC) and to collect data for extending the MTU 1-D, 2-layer model to include the simulation of active regeneration. The engine used in this study was a 2002 Cummins ISM turbocharged 10.8 L heavy-duty diesel engine with cooled EGR. The exhaust after-treatment system consisted of a Johnson Matthey DOC and CPF (a CCRT.) Steady-state loading experiments at 20% load at rated speed were performed for different times in order to achieve three particulate matter loadings of 1.1, 2.2 and 4.1 grams of particulate/liter of filter. Active regeneration was carried out at three CPF-inlet temperatures of 500, 550 and 600°C to cover a range of temperatures and filter loadings for thermal regeneration. The dependent data of fuel usage, time of regeneration, mass of PM oxidized and maximum substrate temperature are presented as a function of mass loading and inlet CPF temperature. The results show that higher CPF-inlet temperature and particulate matter mass loading are more effective for regeneration of the CPF and lower fuel usage in grams of PM oxidized per gallon of fuel used whereas low temperatures and lower mass loadings were not as effective due to lower reaction rates. 90% of the HC from the diesel fuel injection were oxidized across the DOC while the other 10% were oxidized across the CPF under the test conditions.