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Continuously Regenerating Particulate Filters Part 2

Performance and Durability Evaluation of Continuously Regenerating Particulate Filters on Diesel Powered Urban Buses at NY City Transit - Part II

• Sougato Chatterjee, Ray Conway, Diesel Emission Control Systems, Johnson Matthey, CSD
• Thomas Lanni, Shida Tang, Brian P. Frank, Division of Air Resources, New York State Department of Environmental Conservation
• Deborah Rosenblatt, Environment Canada
• Christopher Bush, Dana Lowell, New York City Metropolitan Transit Authority
• James Evans, Equilon Enterprises LLC
• Robert McLean, Corning Inc.
• Steven Levy, Rad Energy

Summary

Particulate emission from diesel engines is one of the most important pollutants in urban areas. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled "Clean Diesel Vehicle Air Quality Project" was initiated by NY City Transit under the supervision of NYSDEC and with active participation from several industry partners.

Under this program, 25 NY City transit buses with DDC Series 50 engines were equipped with continuously regenerating diesel particulate filter systems (the CRT^TM system from Johnson Matthey) and were operated with ultra low sulfur diesel (<30 ppm S) in transit service in Manhattan beginning in February 2000. These buses were previously evaluated during a baseline emissions testing period of 9 months to verify the emissions reduction capability of the continuously regenerating diesel particulate filter technology. In the second phase of the program, reported here, the buses were further evaluated over a 9 to 12 month durability testing period for operations, maintainability and durability of the particulate filter, including extensive emissions testing under transient cycles on a chassis dynamometer.

The on-road operational data over fourteen months showed stable exhaust back pressure with the diesel particle filters, indicating successful filter regeneration. No adverse operational or maintenance issues were observed which can be attributed to the filter system. The emissions results from the post durability (after 9-12 months) testing exhibited >90% reductions in CO and PM and >70% for HC, with the particulate filter. In addition, >99% reductions in carbonyls, >72% in PAH and 70-99% VOC reductions were also achieved. In this report, the post durability emissions testing data from the NY City Clean Diesel Vehicle Air Quality Project are discussed in detail. In addition, the on-road performance of the diesel particulate filter equipped buses after the durability period is also reported.