Development of Efficient Urea-SCR Systems for EPA 2010-Compliant Medium Duty Diesel Vehicles 2011-01-1309

The U.S. Environmental Protection Agency (EPA) issued new emissions regulations, which came into effect in January, 2010. These EPA 2010 regulations are the most stringent emissions standards in the world, reducing both particulate matter (PM) and nitrogen oxides (NOx) to nearly zero levels. Hino Motors improved upon its previous EPA 2007-compliant engine, developing a new exhaust after-treatment system in which a Diesel Particulate active Reduction System (DPR), a Urea-Selective Catalytic Reduction (SCR) System and a Burner System are employed to meet EPA 2010 emissions regulations for medium duty commercial vehicles. DPR was already developed and utilized to reduce PM to meet EPA 2007 standards, but the Urea-SCR System is newly developed technology used to reduce NOx emissions to comply with EPA2010 emissions regulations. In addition, a Burner System is used to elevate exhaust gas temperatures in order to improve both SCR performance and DPR active Regeneration. The combined utilization of these systems, enables significant NOx reduction, achieving levels below 0.2g/bhp-hr (0.27g/kWh) as well as PM levels below 0.01g/bhp-hr (0.013g/kWh) under FTP cycle operating conditions. This paper reports the development approaches and results.