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Sensors 2017, 17(12), 2746; https://doi.org/10.3390/s17122746

Radio-Frequency-Controlled Urea Dosing for NH3-SCR Catalysts: NH3 Storage Influence to Catalyst Performance under Transient Conditions

1
Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95447 Bayreuth, Germany
2
Continental Automotive GmbH, Division Powertrain, 93055 Regensburg, Germany
3
Ford Research and Innovation Center, Dearborn, MI 48124, USA
*
Author to whom correspondence should be addressed.
Received: 24 October 2017 / Accepted: 23 November 2017 / Published: 28 November 2017
(This article belongs to the Section Chemical Sensors)
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Abstract

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NOx emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH3) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH3 loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH3 storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH3 storage levels, and NH3 target curves. It could be clearly demonstrated that the right NH3 target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NOx conversion efficiency and without NH3 slip. View Full-Text
Keywords: radio-frequency (RF); NH3 SCR; NH3 storage; NOx conversion; NH3 slip; direct control; microwave cavity perturbation; transient conditions; storage influence radio-frequency (RF); NH3 SCR; NH3 storage; NOx conversion; NH3 slip; direct control; microwave cavity perturbation; transient conditions; storage influence
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Dietrich, M.; Hagen, G.; Reitmeier, W.; Burger, K.; Hien, M.; Grass, P.; Kubinski, D.; Visser, J.; Moos, R. Radio-Frequency-Controlled Urea Dosing for NH3-SCR Catalysts: NH3 Storage Influence to Catalyst Performance under Transient Conditions. Sensors 2017, 17, 2746.

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