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 Demonstration Program” has been initiated by NY City Transit under the supervision of NY State DEC and with active participation from several industrial partners.
Under this program, several NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter system and are operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses are being evaluated over a 8-9 month period for operations, maintainability and durability of the particulate filter. In addition, an extensive emissions testing program is being carried out under transient cycles on a chassis dyno to evaluate the emissions reductions obtained with the particle filter.
The on-road operational data over eight months showed stable exhaust back pressure with the 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 first phase of testing exhibited >90% reductions in CO, HC and PM with the particulate filter. In addition, >99% reductions in Carbonyls and up to 80% PAH and 94% NO2-PAH destructions were also achieved.
In this paper, the operational and emissions testing data from the NY City Clean Diesel Demonstration Program are discussed in detail.