Procedure Development and Experimental Study of Passive Particulate Matter Oxidation in a Diesel Catalyzed Particulate Filter Michigan Technological University

Format:

Conference/Event

Author/Creator:

Hutton, Hutton, author.

Contributor:

Johnson, John H.

Keith, Jason

Naber, Jeffrey

Conference Name:

SAE 2012 World Congress & Exhibition (2012-04-24 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

The passive oxidation of particulate matter (PM) in a dieselcatalyzed particulate filter (CPF) was investigated in a series ofexperiments performed on two engines. A total of ten tests werecompleted on a 2002 Cummins 246 kW (330 hp) ISM and a 2007 Cummins272 kW (365 hp) ISL. Five tests were performed on each engine todetermine if using engine technologies certified to differentemissions regulations has an impact on the passive oxidationcharacteristics of the PM.A new experimental procedure for passive oxidation testing wasdeveloped and implemented for the experiments. In order toinvestigate the parameters of interest, the engines were initiallyoperated at a steady state loading condition where the PMconcentrations, flow rates, and temperatures were such that theaccumulation of PM within the CPF was obtained in a controlledmanner. This engine operating condition was maintained until a CPFPM loading of 2.2 ±0.2 g/L was obtained. The engine operatingconditions were then changed in order to vary the parameters ofinterest and perform the passive oxidation stage of the test.The test matrix was designed to concentrate on the variablesthat most affect passive oxidation of PM within the CPF. Thesevariables include NO₂ and NO concentrations into the CPF, theNO₂/PM and NOx/PM ratios at the inlet of the CPF,exhaust temperature, and the exhaust flow rate. The test matrixprovided for a wide range of conditions including average CPFtemperatures from 260 to 460°C, NO₂/PM mass ratios from 3 to 59,NOx/PM mass ratios from 8 to 160, and exhaust mass flowrates of 5.6 to 18.0 kg/minutes By gaining a better understanding ofhow these variables affect passive oxidation, engine operatingconditions can be selected that optimize the use of thisregeneration method. This will reduce the dependency on activeregenerations to clean the filter and the fuel penalty associatedwith this strategy.Experimental results during the loading stage of the testsdemonstrated that the PM generated by each engine under similaroperating conditions had similar oxidation rates with different NO₂and NO concentrations at the CPF inlet. Results from the passiveoxidation portion of the experiments show a strong correlationbetween the reaction rate and the CPF average temperature. Whenperforming a mass balance across the CPF, calculations for some ofthe experiments indicate that at temperatures less than 400°C,assuming that PM oxidation is only accomplished by NO₂ oxidizingthe PM, more NO₂ is consumed in the CPF than what is available atthe CPF inlet. The hypothesis was that back diffusion of NO₂ fromthe catalyst on the CPF substrate wall occurs. Calculations of thePéclet number within the CPF showed that the transport of NO₂ isdominated by diffusion under the operating conditions in theseexperiments. This finding indicates that additional NO₂ could beback diffusing into the PM cake layer after NO is oxidized into NO₂at the CPF catalyst surface which would then account for theadditional PM oxidation that occurred in the CPF

Notes:

Vendor supplied data

Publisher Number:

2012-01-0851

Access Restriction:

Restricted for use by site license