Combination of Wirebound and Microwave Measurements for In Situ Characterization of Automotive Three-Way Catalysts

Reib, Sebastian; Spörl, Matthias; Hagen, Gunter; Fischerauer, Gerhard; Moos, Ralf

doi:10.1109/jsen.2010.2058798

Cited by 28 publications

(21 citation statements)

References 16 publications

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“…For example, it can be used to monitor the state of selective catalytic reduction (SCR) catalysts (NH 3 -storage) [11,12], three way catalysts (oxygen loading) [13], or lean NO x traps (NO x loading or state of regeneration) [14]. Overviews are given in the reviews [15,16].…”

Section: Fundamentalsmentioning

confidence: 99%

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

et al. 2016

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Diesel Particulate Filters (DPF) are an essential part of today's diesel exhaust gas aftertreatment systems. For an effective filter regeneration strategy, the precise knowledge of the actual trapped soot mass is essential. Besides the state-of-the-art technology of determining the soot load via pressure drop and/or model-based, a microwave-based method enables direct and in situ soot load detection. Thereby, an electric field is impressed into the filter housing and the power transmission is measured, which correlates with the soot load. In this study, influencing parameters, especially temperature and humidity, are examined and compared to the sensitivity towards soot accumulation. Measurements were conducted in a laboratory test bench with a filter-core, which had been previously loaded with soot in an engine dynamometer. While humidity does not have a notable effect, the influence of temperature needs to be considered for real world application. Finally, a complete filter regeneration of the DPFcore in the laboratory test bench could be monitored with the microwave-based system. The carbon balance-derived burned soot mass coincides very well with the microwave derived transmission parameter.

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Section: Fundamentalsmentioning

confidence: 99%

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

et al. 2016

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“…This microwave-based method has been successfully studied in lab experiments [11] as well as in an engine dynamometer test benches [12]. Even for novel exhaust catalyst systems, like NH3-SCR catalysts, where the amount of stored ammonia needs to be detected [13] or for diesel particulate filters, where the amount of stored soot is an important measurand [14], this microwave-based technique can be applied.…”

Section: Introductionmentioning

confidence: 99%

“…Further details on the microwave cavity perturbation method applied in the automotive exhaust can be found in [15,18,19]. Prior investigations with this method on the state observation of three-way catalysts with the size of ∅ 4.66″ × 6″ (∅ 11.84 cm × 15.24 cm; full size as it is installed in the exhaust pipe) [11,12,20] and ∅ 1″ × 3″ (∅ 2.54 cm × 7.62 cm; typical lab sample) [6,8] have shown that there is a good correlation between the resonance parameter "resonance frequency" and the catalysts' oxidation states.…”

Section: Introductionmentioning

confidence: 99%

In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies

2015

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Initial studies on aging detection of three way catalysts with a microwave cavity perturbation method were conducted. Two physico-chemical effects correlate with the aging state. At high temperatures, the resonance frequencies for oxidized catalysts (λ = 1.02) are not influenced by aging, but are significantly affected by aging in the reduced case (λ = 0.98). The catalyst aging state can therefore potentially be inferred from the resonance frequency differences between reduced and oxidized states or from the resonance frequency amplitudes during lambda oscillations. Secondly, adsorbed water at low temperatures strongly affects the resonance frequencies. Light-off experiment studies showed that the resonance frequency depends on the aging state at temperatures below the oxygen storage light-off. These differences were attributed to different water sorption capabilities of differently aged samples due to a surface area decrease with proceeding aging. In addition to the aging state, the water content in the feed gas and the temperature affect the amount of adsorbed water, leading to different integral electrical material properties of the catalyst and changing the resonance properties of the catalyst-filled canning. The classical aging-related properties of the catalyst (oxygen storage capacity, oxygen storage light-off, surface area), agreed very well with data obtained by the microwave-based method. OPEN ACCESSAppl. Sci. 2015, 5 175

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“…Compared to l-probe-based air-to-fuel control, the RF approach could be advantageous with regard to future OBD for better monitoring of exhaust aftertreatment components. The effect of changing transmission coefficients could be reproduced and is a reliable indication of the oxygen storage in the TWC [51]. Furthermore, it is shown that cross-effects of water, carbon monoxide, carbon dioxide, and gas flow rate can be neglected [52].…”

Section: Radio Frequency-based Catalyst Gaugingmentioning

confidence: 99%

New Approaches for Exhaust Gas Sensing

Moos

2011

Springer Series on Chemical Sensors and Biosensors

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Steadily increasing emission standards for passenger cars and heavy duty vehicles combined with the need for fuel efficiency lead to novel powertrain concepts, for example to leanly operated gasoline direct injection engines, or to novel exhaust gas aftertreatment concepts such as Lean NO x Traps (LNT), ammonia selective catalytic reduction catalysts for NO x reduction (SCR), or even to a combination of both. Also, diesel particulate filters (DPF) are in series production.To control these novel exhaust gas aftertreatment systems and to monitor onboard the proper operation of these systems (on-board diagnosis, OBD), novel exhaust gas sensors are required or are at least be very helpful. Since the development of exhaust gas sensors has always to be seen in interaction with the corresponding exhaust gas aftertreatment systems, novel types of exhaust gas sensors have gained in importance just recently, when the time was ripe for novel exhaust gas aftertreatment concepts. This article reports on several types of NO x sensors and ammonia sensors.Additionally, a very recent novel concept is presented. Here, the catalyst itself works as a sensing device that gives directly information on its own status. The readout can be wirebound (demonstrated for LNT and SCR) or even be wireless by applying radio frequency techniques. It will be shown that this allows to detect the oxygen loading degree of three-way catalysts very precisely. It can be also applied to determine the ammonia loading of SCR catalysts and the soot loading of DPF.As a conclusion, these novel methods may provide a future alternative for low emission-aiming engine control as well as for OBD of low emission vehicles with novel exhaust gas aftertreatment systems. However, it is clear that all novel sensors or systems do not only have to meet the technical requirements but also have to be very inexpensive, reliable, and cost effective.R. Moos (*)

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Combination of Wirebound and Microwave Measurements for In Situ Characterization of Automotive Three-Way Catalysts

Cited by 28 publications

References 16 publications

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies

New Approaches for Exhaust Gas Sensing

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