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Article

Determination of the Dielectric Properties of Storage Materials for Exhaust Gas Aftertreatment Using the Microwave Cavity Perturbation Method

1
Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95440 Bayreuth, Germany
2
Institute of Energy Research and Physical Technologies, Clausthal University of Technology, 38640 Goslar, Germany
*
Author to whom correspondence should be addressed.
Sensors 2020, 20(21), 6024; https://doi.org/10.3390/s20216024
Received: 2 October 2020 / Revised: 16 October 2020 / Accepted: 20 October 2020 / Published: 23 October 2020
(This article belongs to the Section Chemical Sensors)
Recently, a laboratory setup for microwave-based characterization of powder samples at elevated temperatures and different gas atmospheres was presented. The setup is particularly interesting for operando investigations on typical materials for exhaust gas aftertreatment. By using the microwave cavity perturbation method, where the powder is placed inside a cavity resonator, the change of the resonant properties provides information about changes in the dielectric properties of the sample. However, determining the exact complex permittivity of the powder samples is not simple. Up to now, a simplified microwave cavity perturbation theory had been applied to estimate the bulk properties of the powders. In this study, an extended approach is presented which allows to determine the dielectric properties of the powder materials more correctly. It accounts for the electric field distribution in the resonator, the depolarization of the sample and the effect of the powder filling. The individual method combines findings from simulations and recognized analytical approaches and can be used for investigations on a wide range of materials and sample geometries. This work provides a more accurate evaluation of the dielectric powder properties and has the potential to enhance the understanding of the microwave behavior of storage materials for exhaust gas aftertreatment, especially with regard to the application of microwave-based catalyst state diagnosis. View Full-Text
Keywords: microwave cavity perturbation; radio frequency; resonant frequency; quality factor; dielectric properties; depolarization; powders; ceria; exhaust gas aftertreatment; on-board diagnosis (OBD) microwave cavity perturbation; radio frequency; resonant frequency; quality factor; dielectric properties; depolarization; powders; ceria; exhaust gas aftertreatment; on-board diagnosis (OBD)
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MDPI and ACS Style

Steiner, C.; Walter, S.; Malashchuk, V.; Hagen, G.; Kogut, I.; Fritze, H.; Moos, R. Determination of the Dielectric Properties of Storage Materials for Exhaust Gas Aftertreatment Using the Microwave Cavity Perturbation Method. Sensors 2020, 20, 6024. https://doi.org/10.3390/s20216024

AMA Style

Steiner C, Walter S, Malashchuk V, Hagen G, Kogut I, Fritze H, Moos R. Determination of the Dielectric Properties of Storage Materials for Exhaust Gas Aftertreatment Using the Microwave Cavity Perturbation Method. Sensors. 2020; 20(21):6024. https://doi.org/10.3390/s20216024

Chicago/Turabian Style

Steiner, Carsten, Stefanie Walter, Vladimir Malashchuk, Gunter Hagen, Iurii Kogut, Holger Fritze, and Ralf Moos. 2020. "Determination of the Dielectric Properties of Storage Materials for Exhaust Gas Aftertreatment Using the Microwave Cavity Perturbation Method" Sensors 20, no. 21: 6024. https://doi.org/10.3390/s20216024

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