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

Abstract

We report that the passive ammonia (NH 3) selective catalytic reduction (SCR) system is a potential approach for controlling nitrogen oxide (NOx) emissions from lean-burn gasoline engines based on utilizing NH 3 generated by a three-way catalyst (TWC) during brief periods of fuel-rich engine operation. NH 3 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 NH 3 storage capacity highly dependent on exhaust temperatures, proper system architecture and engine operating strategy are needed for effective NH 3 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 NH 3 generation and utilization, and NOx reduction in the passive SCRmore » 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.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
OSTI Identifier:
1550752
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Emission Control Science & Technology
Additional Journal Information:
Journal Volume: 5; Journal Issue: 3; Journal ID: ISSN 2199-3629
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 54 ENVIRONMENTAL SCIENCES; Passive SCR; TWC; Lean NOx; NH3 formation; Lean gasoline

Citation Formats

Prikhodko, Vitaly Y., Pihl, Josh A., Toops, Todd J., and Parks, II, James E. Passive SCR Performance Under Pseudo-Transient Cycle: Challenges and Opportunities for Meeting Tier 3 Emissions. United States: N. p., 2019. Web. doi:10.1007/s40825-019-00126-1.
Prikhodko, Vitaly Y., Pihl, Josh A., Toops, Todd J., & Parks, II, James E. Passive SCR Performance Under Pseudo-Transient Cycle: Challenges and Opportunities for Meeting Tier 3 Emissions. United States. doi:10.1007/s40825-019-00126-1.
Prikhodko, Vitaly Y., Pihl, Josh A., Toops, Todd J., and Parks, II, James E. Wed . "Passive SCR Performance Under Pseudo-Transient Cycle: Challenges and Opportunities for Meeting Tier 3 Emissions". United States. doi:10.1007/s40825-019-00126-1.
@article{osti_1550752,
title = {Passive SCR Performance Under Pseudo-Transient Cycle: Challenges and Opportunities for Meeting Tier 3 Emissions},
author = {Prikhodko, Vitaly Y. and Pihl, Josh A. and Toops, Todd J. and Parks, II, James E.},
abstractNote = {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.},
doi = {10.1007/s40825-019-00126-1},
journal = {Emission Control Science & Technology},
number = 3,
volume = 5,
place = {United States},
year = {2019},
month = {7}
}

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Works referenced in this record:

Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine
journal, April 2016

  • Prikhodko, Vitaly Y.; Parks, James E.; Pihl, Josh A.
  • SAE International Journal of Engines, Vol. 9, Issue 2, p. 1289-1295
  • DOI: 10.4271/2016-01-0934

Three-Way Catalyst Design for Urealess Passive Ammonia SCR: Lean-Burn SIDI Aftertreatment System
conference, April 2011

  • Kim, Chang Hwan; Perry, Kevin; Viola, Michael
  • SAE 2011 World Congress & Exhibition
  • DOI: 10.4271/2011-01-0306