Browse Publications Technical Papers 2005-01-1861

An Investigation into the Emissions Reduction Performance of an SCR System Over Two Years' In-Use Heavy-Duty Vehicle Operation 2005-01-1861

Increasingly stringent oxides of nitrogen (NOx) and particulate matter (PM) regulations worldwide have prompted considerable activity in developing emission control technology to reduce the emissions of these two constituents from heavy-duty diesel engines. NOx has come under particular scrutiny by regulators in the US and in Europe with the promulgation of very stringent regulation by both the US Environmental Protection Agency (EPA) and the European Union (EU). In response, heavy-duty engine manufacturers are considering Selective Catalytic Reduction (SCR) as a potential NOx reduction option. While SCR performance has been well established through engine dynamometer evaluation under laboratory conditions, there exists little data characterizing SCR performance under real-world operating conditions over time.
This project evaluated the field performance of ten SCR units installed on heavy-duty Class 8 highway and refuse trucks. Additionally, five of these vehicles were operated with passive diesel particulate filters (DPFs) in tandem with the SCR units to further characterize the emission reduction capabilities of combining these technologies. Three of these vehicles were selected and comprehensively tested on a heavy-duty chassis dynamometer for criteria pollutants and ammonia (NH3). Testing was performed in two phases, the first after one year of in-use operation, and again after a second year.
The SCR units performed well with no deterioration in NOx performance after significant mileage accumulation. On average, NOx reductions after two rounds of testing were between 80% and 90%.
Hydrocarbons (HC) and carbon monoxide (CO) emission reductions met expectations based on previous test cell results [1,2,3]. PM emission reductions were below expectations possibly due to installation of non-degreened DPFs, sulfate-make, and/or system deterioration. It is difficult to draw conclusions from PM results without repeat of tests and more in-depth post-test PM analysis.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Catalytic Filter Systems with Direct and Indirect Soot Oxidation Activity


View Details


Development of Urea-SCR System for Heavy-Duty Commercial Vehicles


View Details


Tier 2 Intermediate Useful Life (50,000 Miles) and 4000 Mile Supplemental Federal Test Procedure (SFTP) Exhaust Emission Results for a NOx Adsorber and Diesel Particle Filter Equipped Light-Duty Diesel Vehicle


View Details