skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Passive SCR Performance Under Pseudo-Transient Cycle: Challenges and Opportunities for Meeting Tier 3 Emissions

Journal Article · · Emission Control Science & Technology
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
+ Show Author Affiliations

We report that the passive ammonia (NH3) selective catalytic reduction (SCR) system is a potential approach for controlling nitrogen oxide (NOx) emissions from lean-burn gasoline engines based on utilizing NH3 generated by a three-way catalyst (TWC) during brief periods of fuel-rich engine operation. NH3 generated by the TWC is stored and available to reduce NOx on a downstream SCR catalyst during subsequent periods of lean engine operation. Control of the overall passive SCR process can be more challenging than current urea-based approach because it depends explicitly on fuel-rich engine operation, which must be implemented in the context of transient engine operation. Under transient engine operation, significant variation in SCR temperatures is also to be expected. With NH3 storage capacity highly dependent on exhaust temperatures, proper system architecture and engine operating strategy are needed for effective NH3 utilization over the SCR catalyst. In this study, the performance of a passive SCR system was evaluated on a 2.0-l BMW lean-burn gasoline direct injection engine under 6-mode pseudo-transient cycle. The aim of this work is to understand how various engine operating strategies change the dynamics of NH3 generation and utilization, and NOx reduction in the passive SCR system. A 5.9% fuel economy improvement relative to stoichiometric-only operation with 0.018 g/mi of NOx + NMHC emissions were demonstrated over 6-mode pseudo-transient cycle; however, CO emissions were twice the emission standard. In conclusion, the results of this work reveal challenges and opportunities for meeting Tier 3 emissions and improving fuel savings benefits.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1550752
Journal Information:
Emission Control Science & Technology, Vol. 5, Issue 3; ISSN 2199-3629
Publisher:
SpringerCopyright Statement
Country of Publication:
United States
Language:
English

References (10)

Passive Ammonia SCR System for Lean-burn SIDI Engines journal April 2010
Passive SCR for lean gasoline NOX control: Engine-based strategies to minimize fuel penalty associated with catalytic NH3 generation journal June 2016
Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine journal April 2016
Lean Gasoline Engine Reductant Chemistry During Lean NOx Trap Regeneration journal August 2010
Potentials of the Spray-Guided BMW DI Combustion System conference April 2006
Effects of NO X Storage Component on Ammonia Formation in TWC for Passive SCR NO X Control in Lean Gasoline Engines conference April 2018
Ammonia Generation over TWC for Passive SCR NO X Control for Lean Gasoline Engines journal April 2014
European Lean Gasoline Direct Injection Vehicle Benchmark conference April 2011
Three-Way Catalyst Design for Urealess Passive Ammonia SCR: Lean-Burn SIDI Aftertreatment System conference April 2011
NMOG Emissions Characterizations and Estimation for Vehicles Using Ethanol-Blended Fuels journal January 2012

Figures / Tables (14)

Table 2-1(p. 4)table Table 2-1
Table 2-2(p. 4)table Table 2-2
Figure 2.1(p. 6)figure Figure 2.1
Figure 2.2(p. 7)figure Figure 2.2
Table 2-3(p. 8)table Table 2-3
Figure 2.3(p. 9)figure Figure 2.3
Figure 3.1(p. 10)figure Figure 3.1
Figure 3.2(p. 12)figure Figure 3.2
Figure 3.3(p. 13)figure Figure 3.3
Figure 3.4(p. 14)figure Figure 3.4
Figure 3.5(p. 15)figure Figure 3.5
Figure 3.6(p. 17)figure Figure 3.6
Figure 3.7(p. 17)figure Figure 3.7
Figure 3.8(p. 18)figure Figure 3.8

Similar Records

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
54 ENVIRONMENTAL SCIENCES
Passive SCR
TWC
Lean NOx
NH3 formation
Lean gasoline