In urban areas, particulate emission from diesel engines is one of the pollutants of most concern. 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” has been 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 have been equipped with continuously regenerating diesel particulate filter systems and have been operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000.
These buses were evaluated over a 9 month period for operations, maintainability and durability of the particulate filter. In addition, an extensive emissions testing program was carried out under transient cycles on a chassis dyno to evaluate the emissions reductions obtained with the particulate filter, at the beginning and at the end of the 9 - 12 months durability period.
The on-road operational data over fourteen months showed stable exhaust back pressure with the diesel particulate 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 paper, the post durability emission testing data from the NY City Clean Diesel Vehicle Air Quality Project are discussed in detail. In addition, the on-road performance of the CRT® filter equipped buses is also reported for the durability period.