|Diagram of sample NOx adsorber process from Johnson Matthey.|
Cummins Inc. will participate in a public-private partnership led by the California South Coast Air Quality Management District (SCAQMD) to demonstrate advanced diesel engine emissions control systems meeting the stringent EPA 2010 on-highway standard.
Next-generation Cummins aftertreatment research and technology will be utilized on the Cummins ISL 9-liter engine to verify the emissions reduction capability of a combined system incorporating both a Diesel Particulate Filter and NOx Adsorber.
The project was awarded after a competitive bid based on both technical and cost criteria.
The project is focused on demonstrating very low emissions for waste collection vehicles operating in urban areas. The engine technology employed must reduce Particulate Matter emissions to 0.01 gram per brake horsepower hour (g/bhp-hr) and Nitrogen Oxides to 0.2 g/bhp-hr. The program will require a durability evaluation to ensure the test engine final build meets the demanding duty cycle associated with a refuse collection vehicle.
We’ve already seen great strides made by natural gas engine manufacturers and announcements that these natural gas engines will meet very tough 2010 emissions standards by 2007. This collaborative research will give added assurances that diesel technologies will make similar strides. Multiple fuel technologies meeting the 2010 standards as early as possible will provide fleet operators a variety of choices to meet their needs and help advance the state of knowledge on advanced engine control technologies.—Dr. Barry Wallerstein, SCAQMD Executive Officer
NOx adsorbers are catalytic devices, developed in the late 1990s, that use a combination of base metal oxide and precious metal coating to that adsorb NOx from the exhaust under lean conditions and convert it to nitrogen during a regeneration cycle using a fuel-rich, low oxygen stream. In concept, adsorber technology offers considerable NOx reduction capabilities, but performance issues related to durability, operating range and fuel economy have limited their real-world viability.
Regeneration of the adsorber requires elimination of all excess oxygen in the exhaust gas for a short period of time—accomplished either by operating the engine rich, or by operating the exhaust flow through the catalyst rich by injecting fuel prior to the adsorber. In either case, the engine and catalyst need to function as a system.
Cummins has worked with Oak Ridge National Laboratory on the basic science necessary to effectively utilize the catalyst systems in a NOx Adsorber.
An interagency funding agreement between the SCAQMD, California Air Resources Board (CARB) and the U.S. Department of Energy (DOE) will contribute $1,450,000 toward the cost of the project. Cummins development and testing costs are anticipated to cost almost twice this amount over the two-year project schedule.
Fundamental Studies of NOx Adsorber Materials; Pacific Northwest National Laboratory