NOx sensor cross sensitivity model and simultaneous prediction of NOx and NH3 slip from automotive catalytic converters under real driving conditions

Plá, Benjamín; Piqueras, Pedro; Bares, Pau; Aronis, André

doi:10.1177/1468087420966406

Cited by 13 publications

(6 citation statements)

References 27 publications

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“…The NH 3 slip calculation requires a cross sensitivity estimation. It has been reported in Pla et al 39 and Jiang et al 40 that the cross-sensitivity factor is not constant and may depend on the NH 3 concentration. Figure 5 shows the correlation of the K CS with NH 3 for 20 test cycles, including transient and steady state conditions.…”

Section: Artificial Neural Network Model For No X and Nh 3 Slip Predi...mentioning

confidence: 95%

Simultaneous NOx and NH3 slip prediction in a SCR catalyst under real driving conditions including potential urea injection failures

Plá

Piqueras

Bares

et al. 2021

International Journal of Engine Research

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To reach the emission limits imposed by governments and reduce the negative impact on the environment, the use of aftertreatment systems has become essential for internal combustion engine (ICE) based powertrains. In particular, the selective catalytic reduction (SCR) system is a widespread aftertreatment technology with high efficiency for [Formula: see text] abatement which shows complex dynamics and requires urea injection as reducing agent. Current urea injection strategies usually rely on the [Formula: see text] emissions feedback. This work presents a model for the on-line simultaneous prediction of [Formula: see text] and [Formula: see text] emissions after the SCR catalyst, allowing the emissions estimation even in conditions of urea injector failure, when it is not possible to rely on the injector feedback signal. The proposed model is based on state of the art on-board after-treatment instrumentation and proposes an extended Kalman filter (EKF) to combine a data-based model and the analysis of sensor signals to provide a reliable estimation of [Formula: see text] and [Formula: see text] slip. The proposed strategy is experimentally assessed in dynamic driving cycles, such as Worldwide harmonised Light vehicles Test Cycle (WLTC) and Standardised Random Test (RTS). The proposed method is evaluated in standard conditions (without failures) and with urea injection failures of 25% and 120% of the nominal injection amount. As a result, the prediction on [Formula: see text] and [Formula: see text] slip has been improved in all injection failure conditions, by an overall average of 47.8% and 61.8%, respectively, when compared to state-of-the-art control oriented models (physically based zero dimensional model or data-based).

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Section: Artificial Neural Network Model For No X and Nh 3 Slip Predi...mentioning

confidence: 95%

Simultaneous NOx and NH3 slip prediction in a SCR catalyst under real driving conditions including potential urea injection failures

Plá

Piqueras

Bares

et al. 2021

International Journal of Engine Research

Self Cite

View full text Add to dashboard Cite

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“…On the one hand, this assumption responds to the need of NH3 slip estimation with low computational effort. On the other hand, the NO2 concentration at the ASC inlet is several orders of magnitude lower than that of NO [23]. The NO2 estimation would require additional model features concerning combustion conditions as well as the transport of NO2 along the catalyst, unbalancing the computational effort to accuracy trade-off negatively.…”

Section: Asc Modelmentioning

confidence: 99%

“…The NH3 cross-sensitivity model for the correction of the NOx sensor signal is described in detail by Pla et al [23]. This model is based on the estimation of the oxidation rate of NH3 to NOx within the sensor cell.…”

Section: Nh3 Cross-sensitivity For Nox Sensor Correctionmentioning

confidence: 99%

“…This oxidation is highly dependent on the sensor cell temperature. Since this temperature cannot be measured, the energy balance in the sensor cell was solved assuming negligible cell volume, no heat transfer between the cell and the environment, constant electric heating rate and exothermics proportional to NH3 molar fraction [23]. According to these hypotheses and rearranging the energy balance, the sensor cell temperature was finally expressed as…”

Section: Nh3 Cross-sensitivity For Nox Sensor Correctionmentioning

confidence: 99%

“…From the point of view of on-board measuring of both NOx and NH3, the most common approach is the use of amperometric sensors based on ZrO2 pumping cell [22]. This type of sensor presents NH3 cross-sensitivity as main drawback, what means that the actual NOx emission may not correspond to the sensor signal due to the presence of NH3 [23]. This correction of the crosssensitivity may require the use of NH3 sensors or multiple NOx sensors with different degrees of sensitivity to NH3 [23] at the expense of higher cost.…”

Section: Introductionmentioning

confidence: 99%

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Ammonia Slip Estimation Based on Ammonia Slip Catalyst Control-Oriented Modeling and On-Board Diagnostics NOX Sensor Cross-Sensitivity Analysis

Piqueras

Plá

Sanchis

et al. 2022

Journal of Engineering for Gas Turbines and Power

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The incoming emission regulations for internal combustion engines are gradually introducing new pollutant species, which requires greater complexity of the aftertreatment systems concerning layout, control, and diagnostics. This is the case of ammonia, which is injected into the exhaust gas through urea injections for NOx abatement in selective catalytic reduction (SCR) systems and can also be generated in three-way catalysts. However, ammonia slip requires its oxidation on a dedicated ammonia slip catalyst (ASC). The set composed of the urea injection system, SCR, and ASC requires control tools to ensure high NOx conversion efficiency and compliant ammonia slip under real driving conditions. These tasks are based on the use of NOx sensors ZrO2 pumping cell-based, which has the disadvantage of high cross-sensitivity to ammonia that can affect the measurement of NOx and compromise the SCR-ASC control strategies. The present work proposes a methodology to predict ammonia and NOx tailpipe emissions. For this purpose, a control-oriented ASC model was developed to use its ammonia slip prediction to determine the cross-sensitivity correction of the tailpipe NOx sensor. The model is based on a simplified solution of the transport equations of the species involved in the ASC reaction mechanism. The model was calibrated using steady- and quasi-steady-state tests performed in a Euro 6c engine. Finally, the performance of the proposed methodology to predict NOx and ammonia emissions was evaluated against experimental data corresponding to Worldwide harmonized Light vehicles Test Cycles (WLTC) applying different urea dosing strategies.

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Future Impact and Challenges of Automotive Control

Di Cairano,

Guardiola,

Malikopoulos

et al. 2023

The Impact of Automatic Control Research on Industrial Innovation

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NOx sensor cross sensitivity model and simultaneous prediction of NOx and NH3 slip from automotive catalytic converters under real driving conditions

Cited by 13 publications

References 27 publications

Simultaneous NOx and NH3 slip prediction in a SCR catalyst under real driving conditions including potential urea injection failures

Simultaneous NOx and NH3 slip prediction in a SCR catalyst under real driving conditions including potential urea injection failures

Ammonia Slip Estimation Based on Ammonia Slip Catalyst Control-Oriented Modeling and On-Board Diagnostics NOX Sensor Cross-Sensitivity Analysis

Future Impact and Challenges of Automotive Control

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