Browse Publications Technical Papers 04-13-01-0003
2020-01-09

A Modeling Study of an Advanced Ultra-low NO x Aftertreatment System 04-13-01-0003

This also appears in SAE International Journal of Fuels and Lubricants-V129-4EJ

The 2010 Environmental Protection Agency (EPA) Emission Standard for heavy-duty engines required 0.2 g/bhp-hr over certification cycles (cold and hot Federal Test Procedure [FTP]), and the California Air Resources Board (CARB) standards require upto 90% reduction of overall oxides of nitrogen (NOx) emissions. Similar reductions may be considered by the EPA through its Cleaner Trucks Initiative program. In this article, aftertreatment system components consisting of a diesel oxidation catalyst (DOC); a selective catalytic reduction catalyst on a diesel particulate filter (DPF), or SCR-F; a second DOC (DOC2); and a SCR along with two urea injectors have been analyzed, which could be part of an aftertreatment system that can achieve the 0.02 g/bhp-hr standard. The system performance was evaluated using validated one-dimensional (1D) DOC, two-dimensional (2D) SCR-F, and 1D SCR models at various combinations of inlet ammonia (NH3)-to-NOx ratio (ANR) values for the SCR-F and the SCR to determine the injection rates required to achieve an optimum nitrogen dioxide (NO2)/NOx ratio at the inlets of both the SCR-F and the SCR. A strategy was developed that yielded 99.5% NOx conversion at inlet temperatures from 203° to 450°C, while maximizing particulate matter (PM) oxidation rate in the SCR-F and minimizing the urea consumption rate. These system components have the potential to be robust to variations in the inlet NOx and NH3 concentrations and the NOx conversion performance of the system components.
NOx conversions greater than 95% in the SCR-F and SCR were determined to be primarily due to the fast SCR reaction. The two urea injectors were used to maximize NOx reduction in both devices and SCR-F PM oxidation. For the case with ANR1 = 0, a 90%-100% increase in NO2-assisted PM oxidation in the SCR-F was determined compared to a system without the second DOC and urea injector. Further development of the system components should be pursued in terms of catalyst type, catalyst loading, and external heating along with a close-coupled SCR/DOC or passive NOx adsorbers (PNA) to reduce the light-off time for cold-start emissions control.

SAE MOBILUS

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

Access SAE MOBILUS »

Members save up to 20% off list price.
Login to see discount.
We also recommend:
Book
BOOK

Fundamentals of Engineering High-Performance Actuator Systems

View Details

Book
BOOK

V2V/V2I Communications for Improved Road Safety and Efficiency

View Details

TECHNICAL PAPER

The Challenge Facing AQUAZOLE: Compatibility With New Engine and DPF Technologies

2004-01-1885

View Details

X