This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
About Cross-Sensitivities of NOx Sensors in SCR Operation
Technical Paper
2013-01-1512
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Meeting the upcoming NOx emissions standards is a major challenge for the lean-burn engines, thus requiring a highly efficient exhaust gas aftertreatment. Currently, the Selective Catalytic Reduction (SCR) appears to be the most promising technology, especially when operated with two kinds of reductants: ammonia (generally derived from urea) and ethanol. In order to reach high conversion levels while avoiding the overinjection of the reductant, a very accurate model-based control assisted with at least one NOx sensor is required.
This study focuses on the sensitivity of NOx sensors to the main nitrogenous species encountered: ammonia, isocyanic acid (HNCO) and hydrogen cyanide (HCN). The cross-sensitivity to ammonia is the only one to be already described in literature and already used in the urea-SCR control systems to limit the risks of ammonia-slip. However, HNCO can also be found downstream of a catalyst during urea-SCR if the urea delivery or the catalyst are deficient. With an ethanol-SCR system, the very dangerous HCN might be found if the selectivity of the catalyst deteriorates. Both species were found to interfere with the NOx sensor signal: the observation of the these cross-sensitivities was stated on an engine test-bench while additional characterizations were performed on a synthetic gas bench. Meanwhile, nitrous oxide, ethanol or aldehydes appeared not to bias the sensor signal.
The obtained results suggest that the identified cross-sensitivities may be used to detect the presence of HNCO for urea-SCR or HCN for ethanol-SCR instead of or in addition to ammonia, due to different interference factors. These particularities are intended to help diagnose some failures of the SCR aftertreatment system.
Recommended Content
Authors
Topic
Citation
Frobert, A., Raux, S., Creff, Y., and Jeudy, E., "About Cross-Sensitivities of NOx Sensors in SCR Operation," SAE Technical Paper 2013-01-1512, 2013, https://doi.org/10.4271/2013-01-1512.Also In
References
- Kunimoto , A. , Hasei , M. , Yan , Y. , Gao , Y. et al. New Total-NOx Sensor Based on Mixed Potential for Automobiles SAE Technical Paper 1999-01-1280 1999 10.4271/1999-01-1280
- Inagaki , H. , Oshima , T. , Miyata , S. , and Kondo , N. NOx Meter Utilizing ZrO2 Pumping Cell SAE Technical Paper 980266 1998 10.4271/980266
- Kato , N. , Kokune , N. , Lemire , B. , and Walde , T. Long Term Stable NOx Sensor with Integrated In-Connector Control Electronics SAE Technical Paper 1999-01-0202 1999 10.4271/1999-01-0202
- Riegel J. , Neumann H. and Wiedenmann H.-M. Solid State Ionics 2002 152 153 783
- Zhuiykov , Serge Sensors And Actuators B Chemical 121 2 2007 01 01 639 651 0925-4005
- Ono , T. , Yan , Y. , Hasei , M. , Sato , M. et al. Total-NOx Sensor Based on Mixed-Potential for Detecting of Low NOx Concentrations SAE Technical Paper 2005-01-0451 2005 10.4271/2005-01-0451
- Gao , Jing Sensors And Actuators B Chemical 154 2 2011 01 01 106 110 0925-4005
- Sasaki , H. , Scholl , D. , Parsons , M. , Inagaki , H. et al. Development of an Al2O3/ZrO2-Composite High-Accuracy NOx Sensor SAE Technical Paper 2010-01-0041 2010 10.4271/2010-01-0041
- Walde , Nakasone Smart NOx-Sensor Application in diesel systems 5. International CTI Forum Exhaust Systems 2007
- Hsieh , M.-F. , & Wang , J. Development and experimental studies of a control-oriented SCR model for a two-catalyst urea-SCR system Control Engineering Practice 2011 10.1016/j.conengprac.2011.01.004
- Schar , C. IEEE Transactions On Control Systems Technology 14 4 2006 01 01 641 653 1063-6536
- Suárez , Silvia Catalysis Today 75 1-4 2002 01 01 331 338 0920-5861
- Hsieh , M.-F. , & Wang , J. Development and experimental studies of a control-oriented SCR model for a two-catalyst urea-SCR system Control Engineering Practice 2011 10.1016/j.conengprac.2011.01.004
- DiMaggio , C. , Fisher , G. , Rahmoeller , K. , and Sellnau , M. Dual SCR Aftertreatment for Lean NOx Reduction SAE Int. J. Fuels Lubr. 2 1 66 77 2009 10.4271/2009-01-0277
- Frobert et al. Analysis of the coupling of HC-SCR by ethanol and NH 3 -SCR on real engine emissions Topics In Catalysis , in press
- Yeom Young Hoon , Wen Bin , Sachtler Wolfgang M. H. , Weitz Eric NOx Reduction from Diesel Emissions over a Nontransition Metal Zeolite Catalyst: A Mechanistic Study Using FTIR Spectroscopy J. Phys. Chem. B 108 17 29 April 2004 5386 5404