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A heavy duty US 2010/Euro VI type emission control system typically consists of diesel oxidation catalyst (DOC), catalyzed soot filter (CSF), urea based selective catalytic NOx reduction (SCR) and NH3 slip control catalyst (AMOX - excluded for this study). The advent of the US 2014 Green House Gas (GHG) rules has established a limit for tailpipe N2O emissions for on-road heavy duty Diesel engines, thus creating new challenges for catalyst design and system/engine calibration. In this paper, we discuss the effects of both catalyst system design and engine calibration on the formation of N2O across SCR catalysts. This study consisted of system testing on engine, modeling and component reactor testing. These three tools were used to evaluate how NO2 to NOx ratio and ammonia to NOx ratio (ANR) affect N2O formation. The study showed that all of the reviewed factors affect tailpipe N2O emissions.

Previous studies have shown that regenerating particulate filters are very effective at reducing particulate matter emissions from diesel engines. Some particulate filters are passive devices that can be installed in place of the muffler on both new and older model diesel engines. These passive devices could potentially be used to retrofit large numbers of trucks and buses already in service, to substantially reduce particulate matter emissions. Catalyst-type particulate filters must be used with diesel fuels having low sulfur content to avoid poisoning the catalyst. A project has been launched to evaluate a truck fleet retrofitted with two types of passive particulate filter systems and operating on diesel fuel having ultra-low sulfur content. The objective of this project is to evaluate new particulate filter and fuel technology in service, using a fleet of twenty Class 8 grocery store trucks. This paper summarizes the truck fleet start-up experience.

The legislative decision to accelerate the implementation of regulations requiring advanced emissions control in India have accelerated the need to advanced emissions control systems. Particulate filters and NOx abatement technology will be needed to meet the new BSVI standards. Integration of these emission control technologies into engine design poses new challenges to the Indian Heavy Duty Diesel Truck Industry. Each new market that implements advanced emission regulations faces challenges that are unique to the local regulation, the local vehicle design, and the local operating conditions. This paper will review the technology options available for BSVI, their strengths and weaknesses, and potential system designs. Additionally this paper will review how critical design factors such as filter regeneration conditions, duty cycle temperatures, and urea injection can affect the system design and catalyst selection.