This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Motor Vehicle Emission Control Quality Monitoring for On-Road Driving: Dynamic Signature Recognition of NO x & NH 3 Emissions
Technical Paper
2020-01-0372
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Motor vehicle emission testing during on-road driving is important to assess a vehicle’s exhaust emission control design, its compliance with Federal regulations and its impact on air quality. The U.S. Environmental Protection Agency (EPA) has been developing new approaches to screen the characteristics of vehicle dynamic emission control behaviors (its operating signature) while driving both on-road and on-dynamometer. The so-called “signature device” used for this testing is equipped with an O2/NOx sensor, thermocouple and GPS to record dynamic exhaust NOx concentration, air fuel ratio-controlled tailpipe lambda (λ), tailpipe temperature and vehicle speed (acceleration).
In the early EPA research, signature screening was used to characterize a vehicle’s PCM control behaviors (cause/effect bijectivity), which help distinguish operation in normal control state-space and abnormal state-space. Currently, signature devices are being used to recognize when ammonia (NH3) has been emitted and to estimate the presence of NOx and NH3 within on-road and on-dyno driving. The presence of NH3 is observed by the signature device’s NOx sensor at times when tailpipe lambda readings are biased rich, after the engine three-way-catalyst (TWC) has warmed up.
To study the production of NH3, EPA established a vehicle test program to gather and evaluate the emissions from on-road driving conditions. The same driving conditions were then replicated on an indoor chassis dynamometer (dyno) while using a bag analyzer bench, a raw exhaust modal bench, and a signature device to measure vehicle emissions and control behaviors.
EPA ascertained, under certain operating conditions, that stoichiometric engine exhaust passing through a TWC can create hydrogen (CO+H2O→H2), which is then available to produce unregulated ammonia (CO+NO+H2→NH3). These reactions can accelerate when the engine operates with slightly rich-biased lambda introduced either by control or by calibration design. Under current Light-Duty Tier 3 emission regulations, NOx and NMOG emissions are counted together, creating an “opportunity” for more of this type of engine operation.
Authors
Topic
Citation
Tang, X., Kargul, J., and McBryde, D., "Motor Vehicle Emission Control Quality Monitoring for On-Road Driving: Dynamic Signature Recognition of NOx & NH3 Emissions," SAE Technical Paper 2020-01-0372, 2020, https://doi.org/10.4271/2020-01-0372.Also In
References
- Tang , X. and McBryde , D. A Simple Test Method to Monitor Emission Control Operating State Space (Emission Control Failure & Defeat Device Recognition) SAE Technical Paper 2016-01-2324 2016 https://doi.org/10.4271/2016-01-2324
- Tang , X. , Caldwell , W. , and McBryde , D. Vehicle Exhaust Emission Control Dynamic Signature Measurement and Analysis - A Method to Detect Emission Testing Irregularities SAE Technical Paper 2018-01-0650 2018 https://doi.org/10.4271/2018-01-0650
- Suarez-Bertoa , R. , Zardini , A. , Lilova , V. et al. Intercomparison of Real-Time Tailpipe Ammonia Measurements from Vehicles Tested over the New World-Harmonized Light-Duty Vehicle Test Cycle (WLTC) Environ Sci Pollut Res 22 10 7450 7460 2015 10.1007/s11356-015-4267-3
- Pak , G. , Matsunaga , A. , Sahni , S. , et al. NH 3 Cross-Sensitivity of a NO x Sensor and NO3 Measurements of Newer-Model Gasoline Light-Duty Vehicles 2019 International Portable Emission Measurement Systems (PEMS) Conference 2019
- Shelef , M. and Gandhi , H.S. Ammonia Formation in Catalytic Reduction of Nitric Oxide by Molecular Hydrogen I. Base Metal Oxide Catalysts Ind. Eng. Chem. Prod. Res. Develop. 11 1 2 11 1972 10.1021/i360041a002
- Shelef , M. and Gandhi , H.S. Ammonia Formation in Catalytic Reduction of Nitric Oxide by Molecular Hydrogen II. Noble Metal Catalysts Ind. Eng. Chem. Prod. Res. Develop. 11 4 393 396 1972 10.1021/i360044a006
- Shelef , M. and Gandhi , H.S. Ammonia Formation in Catalytic Reduction of Nitric Oxide III. The Role of Water Gas Shift, Reduction by Hydrocarbons, and Steam Reforming Ind. Eng. Chem. Prod. Res. Develop. 13 1 80 85 1974 10.1021/i360049a016
- Bradow , R.L. and Stump , F. Unregulated Emissions from Three-Way Catalyst Cars SAE Technical Paper 770369 1977 https://doi.org/10.4271/770369
- Durbin , T.D. , Wilson , R.D. , Norbeck , J.M. et al. Estimates of Emission Rates of Ammonia from Light-Duty Vehicles Using Standard Chassis Dynamometer Test Cycles Atmospheric Environment 36 9 1475 1482 2002 10.1016/S1352-2310(01)00583-0
- Heeb , N.V. , Forss , A.-M. , Brühlmann , S. et al. Three-Way Catalyst-Induced Formation of Ammonia-Velocity- and Acceleration-Dependent Emission Factors Atmospheric Environment 40 31 5986 5997 2006 10.1016/j.atmosenv.2005.12.035
- Li , W. , Perry , K. , Narayanaswamy , K. , Kim , C. et al. Passive Ammonia SCR System for Lean-Burn SIDI Engines SAE Int. J. Fuels Lubr. 3 1 99 106 2010 10.4271/2010-01-0366
- U.S. Environmental Protection Agency https://www.epa.gov/sites/production/files/2016-09/documents/nrci-scr-web-conf.2011-07-25.pdf July 26, 2011