Diesel Engine SCR Control: Current Development and Future Challenges

This paper aims at investigating the fault diagnosis of the selective catalyst reduction (SCR) outlet temperature sensors and fault-tolerant control methods of the SCR system, and three typical faults of downstream temperature sensors were modeled and analyzed to present influences of different faults on the SCR system performances (such as nitrogen oxides (NO x ) emission and conversion efficiency, NH 3 slip, urea dosage and ammonia coverage estimation). A temperature model was established to estimate the SCR outlet temperature, and diagnostics were developed based on the differences between model estimates and sensor measurements. Once a downstream temperature sensor fault was detected, the fault-tolerant control will be enabled, and the output of the sensor may be substituted with the estimates of the model. Thus, SCR performances shall be maintained within the acceptable ranges. Moreover, a 0-D SCR model was also established to validate the capability of diagnostics and fault-tolerant control strategy over the European transient cycle (ETC).

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“…By applying the energy conservation law, the catalyst convertor has the following energy equilibrium [27,36]:…”

Section: Fault Detection and Fault-tolerant Controlmentioning

confidence: 99%

Model-Based Temperature Sensor Fault Detection and Fault-Tolerant Control of Urea-Selective Catalyst Reduction Control Systems

Wang

Zeng

et al. 2018

Energies

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“…Side reactions like formation of NH 4 NO 3 and N 2 O are excluded in this work but can be easily included when necessary as these extra reactions do not pose any additional modeling difficulties. Ammonia adsorption reaction (R1) is a key step in the urea injection-based SCR reactors because the NOx reduction reactions depend on the adsorbed NH 3 . Ammonia oxidation reaction (R2) is an important side reaction which competes with NOx reduction reactions for stored NH 3 .…”

Section: Scr Chemistrymentioning

confidence: 99%

“…Ammonia adsorption reaction (R1) is a key step in the urea injection-based SCR reactors because the NOx reduction reactions depend on the adsorbed NH 3 . Ammonia oxidation reaction (R2) is an important side reaction which competes with NOx reduction reactions for stored NH 3 . NO oxidation reaction (R3) is a reversible reaction which is equilibrium limited at higher temperatures.…”

Section: Scr Chemistrymentioning

confidence: 99%

“…Model-based control is an emerging approach for achieving better SCR control. Skaf et al [2] and Yuan et al [3] recently reviewed current status on the development of SCR control. Reactor modeling usually consists of two layers of mathematical models-reactor models, which capture mass and heat transport in the reactors, and reaction (or kinetic) models, which describe the reaction mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…It is well known that the reaction rates are controlled by external (i.e., fluid to wall) mass transfer at high temperatures, and hence, two-phase models are needed to accurately predict exit conversions in high temperature regions [6,14]. There are other attempts in developing grey-box models with different approaches which are reviewed by Yuan et al [3]. However, instead of a continuous chain connecting detailed and grey-box models, present grey-box models are rather scattered links.…”

Section: Introductionmentioning

confidence: 99%

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Development of ECU Capable Grey-Box Models from Detailed Models—Application to a SCR Reactor

Gundlapally

Papadimitriou

Wahiduzzaman

et al. 2016

Emiss. Control Sci. Technol.

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Selective catalytic reduction (SCR) of NOx with NH 3 is a widely used after-treatment technology for reducing the NOx emissions from diesel engines. Mathematical models play an important role in analyzing and optimizing SCR reactors and also in controller design. Detailed mathematical models of SCR reactors consist of a number of coupled differential and algebraic equations, which can only be solved numerically. Due to the limited computational capability of engine control unit (ECU) and hardware-in-loop (HIL) systems, it is not practical to solve detailed model equations on these systems in real time, and hence, there is a need for reduced-order models. In this work, we provide a systematic procedure for deriving reduced-order models from detailed models of a SCR reactor. This systematic procedure consists of making reasonable assumptions, good input signal design, and system identification procedure. The reduced-order model consists of non-stiff system of equations which can be solved with an explicit solver, is two to three orders of magnitude faster than the detailed model, and has same level of accuracy as detailed model. The proposed model remains fundamentalbased, with model parameters directly related to physical and chemical properties of the catalyst, and can be used on ECU and HIL systems to predict ammonia storage, NOx conversion efficiency, and ammonia slip during transient operating conditions. Moreover, it is shown that the model equations can be easily linearized around various operating points, thus allowing the development of advanced control strategies based on linear control theory. Although mainly demonstrated in the context of SCR reactors, the procedures can be applied to other monolith reactors as well.

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High Pressure DME Spray for Compression Ignition Engines

Leblanc

Zheng

2020

Springer Proceedings in Energy

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Diesel Engine SCR Control: Current Development and Future Challenges

Cited by 68 publications

References 53 publications

Model-Based Temperature Sensor Fault Detection and Fault-Tolerant Control of Urea-Selective Catalyst Reduction Control Systems

Model-Based Temperature Sensor Fault Detection and Fault-Tolerant Control of Urea-Selective Catalyst Reduction Control Systems

Development of ECU Capable Grey-Box Models from Detailed Models—Application to a SCR Reactor

High Pressure DME Spray for Compression Ignition Engines

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