Emission Reductions and Operational Experiences With Heavy Duty Diesel Fleet Vehicles Retrofitted with Continuously Regenerated Diesel Particulate Filters in Southern California 2001-01-0512

Particulate emission control from diesel engines is one of the major concerns in the urban areas in California. Recently, regulations have been proposed for stringent PM emission requirements from both existing and new diesel engines. As a result, particulate emission control from urban diesel engines using advanced particulate filter technology is being evaluated at several locations in California.

Although ceramic based particle filters are well known for high PM reductions, the lack of effective and durable regeneration system has limited their applications. The continuously regenerated diesel particulate filter (CRDPF) technology discussed in this presentation, solves this problem by catalytically oxidizing NO present in the diesel exhaust to NO₂ which is utilized to continuously combust the engine soot under the typical diesel engine operating condition.

A one-year technology validation program is being run on vehicles from several diesel engine fleets in Southern California to evaluate emissions reductions using this CRDPF system and ultra low sulfur diesel fuel. Under this program, vehicles such as fuel tanker trucks, school buses, sanitation trucks, grocery trucks and transit buses have been retrofitted with CRDPFs and are being operated with ultra low sulfur diesel. The program was started in September 1999. As a part of the program, these retrofitted vehicles are being evaluated for on-road operation and emissions reductions. In addition to drivability and maintenance, the on-road exhaust back pressure and temperature with the CRDPFs are being monitored to evaluate successful operation. The emissions testing program involves chassis dyno testing of several vehicles from each fleet to examine the emissions reductions due to the use of ultra low sulfur diesel and the installation of continuously regenerated particle filters.

To date, the results indicate very successful operation of all the vehicles retrofitted with the catalytically regenerated particulate filters. Initial emissions testing show >90% reductions in PM, HC and CO, compared to CARB-fueled vehicles with no particulate filter. Particle sizing analysis also indicates >99% reduction in particle count with the CRDPF.