About Cross-Sensitivities of NOx Sensors in SCR Operation

Frobert, Arnaud; Raux, S.; Creff, Yann; Jeudy, Eric

doi:10.4271/2013-01-1512

Cited by 32 publications

(47 citation statements)

References 13 publications

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“…22 The four-state SCR model considers reactions (5) to (7) and (10) and the oxidation of NO to NO 2 . Details of the SCR model can be presented as (interested readers are referred to the related literature for details)…”

Section: Nh 3 Oxidationmentioning

confidence: 99%

A novel cost-effective robust approach for selective catalytic reduction state estimations using dual nitrogen oxide sensors

Chen

Wang

2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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Urea-based selective catalytic reduction systems have become a promising technique in controlling nitrogen oxide emissions from diesel engines in the past decade. One of the continuing issues is the cross-sensitivity characteristics of the current nitrogen oxide sensors to ammonia in the exhaust, which makes nitrogen oxide sensor readings inaccurate in the presence of ammonia. Although prototype ammonia sensors for mobile selective catalytic reduction applications have been introduced for diesel emission control in the past few years, ammonia sensors are still too expensive to be available for mass-produced diesel engines and selective catalytic reduction systems. In order to address these issues, in this paper, a novel, cost-effective, and robust approach is proposed for estimating the key selective catalytic reduction states including the nitric oxide concentration, the nitrogen dioxide concentration, the ammonia concentration, and the ammonia surface coverage ratio, by utilizing two post-selective-catalytic-reduction nitrogen oxide sensors with different ammonia cross-sensitivity factors. Experimental verification results show that the proposed approach has the potential for precisely estimating the four selective catalytic reduction states. Such a novel approach can be instrumental in reducing the cost of selective catalytic reduction diagnosis, selective catalytic reduction estimation, and advanced selective catalytic reduction controls.

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Section: Nh 3 Oxidationmentioning

confidence: 99%

A novel cost-effective robust approach for selective catalytic reduction state estimations using dual nitrogen oxide sensors

Chen

Wang

2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…For example, a typical after-treatment system for heavyduty diesel vehicles consists of diesel oxidation catalyst (DOC), diesel particulate filter (DPF) and NOx selective catalytic reduction (SCR). The DOC has three primary functions in an integrated emission control system: to oxidize CO and HCs in the exhaust 1) 3) , to burn a large amount of fuel periodically supplied by post-injection for regeneration of the DPF 4) and to oxidize NO to NO2 for enhanced low-temperature NOx reduction by SCR 5) . However, the temperature of exhaust gas emissions from diesel engines has been decreased by the introduction of exhaust gas recirculation (EGR) systems to efficiently reduce engine-exhaust NOx levels.…”

Section: Introductionmentioning

confidence: 99%

Development of Diesel Hydrocarbon Oxidation Catalysts Aimed at Reducing Platinum Group Metals Usage

Haneda

Sasaki

Hamada

2015

J. Jpn. Petrol. Inst.

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Highly active diesel oxidation catalyst for the oxidation of diesel hydrocarbons, with minimal use of platinum group metals, was developed. Pt/Al2O3 showed the highest activity for total oxidation of a mixture of n-decane and 1-methylnaphthalene as model fuel-originated hydrocarbons even after high temperature aging at 750 for 5 h in air. The surface density of acid sites on Al2O3 was found to be important to stabilize the Pt surface in the active metallic state, resulting in high hydrocarbon oxidation activity. The catalytic activity of Pt/Al2O3 was strongly dependent on the Pt dispersion. Based on the findings of in-situ FT-IR spectroscopy, a reaction mechanism was proposed, in which acrylate species as reaction intermediate formed on Pt migrates to the acid-base centers of the Al2O3 surface and then reacts with O2 to form CO2. On the basis of these findings, we successfully developed highly active diesel oxidation catalyst by the addition of Pd with Pt/Pd weight ratio of 3/1 and the use of Al2O3 support modified with acidic additives such as WO3.

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“…Many studies have studied the cross-sensitivity of NH3 on ZRO2 based NOX sensors. However, in these studies NH3 interference on ZRO2 based NOx sensors observed when NH3 concentration above 200 ppm [57], [75]. Nevertheless, Figure 58 shows NH3 concentrations measured during on-road operation is found to be within 10 ppm of NH3 concentrations 95% of the time.…”

Section: Results Of Accuracy and Measurement Variability Of On-board mentioning

confidence: 89%

“…It is found that 90% of the CH4 concentrations are observed within 5 ppm and at this level of CH4 concentrations, no cross-sensitivity of NOx sensors associated with CH4 is observed. However, a study demonstrated the influence of CH4 on onboard NOx sensors accuracy, but during this study NOx sensors were exposed to high levels of CH4 concentrations,400 ppm, in a controlled environment [57]. On-road data collected during cross-Cali study demonstrates that 400 ppm concentration levels of CH4 cannot be seen during realworld HDD vehicle operation.…”

Section: Results Of Accuracy and Measurement Variability Of On-board mentioning

confidence: 90%

Development of an Emissions Monitoring Methodology Using On-Board NOx Sensors and Revision to Current In-Use Emissions Regulatory Protocols

Demirgök¹

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Measurement of in-use emissions from heavy-duty (HD) vehicles under real-world operation has been widely performed by using portable emissions measurement system (PEMS). PEMS serve as an accurate and lightweight emissions measurement system to evaluate in-use emissions from HD vehicles. However, emissions measurement using PEMS instrumentation can be time consuming and labor intensive. Advantage of utilizing already existing on-board sensors such that they can potentially provide an alternative measurement methodology to the PEMS. A successful implementation of an on-board NOx sensor-based methodology for assessing in-use NOx emissions will allow for a cost-effective and simplified approach to monitor real-world, NOx emission rates. The technology of on-board NOx sensors is in its initial stages to be used to monitor in-use NOx emissions and the ability of the sensor to measure NOx concentration during selective catalytic reduction (SCR) activity period is of concern. Furthermore, the on-board NOx sensors are also subject to various cross-sensitivity and durability concerns. The primary objective of this dissertation is to compare the on-board NOx sensor response and accuracy against laboratory grade instrumentation that include PEMS using Non-Dispersive Ultra-Violent (NDUV) and Fourier transform infrared spectroscopy (FTIR) measurement to assess the measurement thresholds of on-board NOx sensors. The study compares the cross-sensitivity of the NOx sensors to ammonia (NH3) concentration in the exhaust. NH3 slip from SCR is believed to interfere with NOx measurements using Zirconium oxide sensors and this study will discuss NH3-NOx cross sensitivity on on-board NOx sensors during real-world HD vehicle activity. Results from this study will compare on-board NOx sensor measurement capabilities and they will be assessed at different power levels related to different SCR conversion efficiency and different NOx concentration levels related to measurements obtained from a laboratory grade emissions

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About Cross-Sensitivities of NOx Sensors in SCR Operation

Cited by 32 publications

References 13 publications

A novel cost-effective robust approach for selective catalytic reduction state estimations using dual nitrogen oxide sensors

A novel cost-effective robust approach for selective catalytic reduction state estimations using dual nitrogen oxide sensors

Development of Diesel Hydrocarbon Oxidation Catalysts Aimed at Reducing Platinum Group Metals Usage

Development of an Emissions Monitoring Methodology Using On-Board NOx Sensors and Revision to Current In-Use Emissions Regulatory Protocols

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