Real-Time Catalyst Monitoring and Diagnostics using Radio Frequency Sensors

Paul  Ragaller, CTS Corporation, Boston Innovation Office

Radio frequency (RF) sensing presents a means for directly monitoring the state of catalysts.  The approach utilizes radio frequency signals to monitor the resonance response of the catalyst contained in a metallic housing.  Changes in the resonance characteristics are directly related to the catalyst storage state (quantity of stored or adsorbed gas species) as well as the catalyst state of health.

This work covers the application of RF sensing to a wide range of catalysts including three-way catalysts (TWC), selective catalytic reduction systems (SCR), and SCR-coated filters (SCR-F).     Results of laboratory bench reactor testing and engine/vehicle evaluations demonstrate the capabilities of the technique to provide direct measurement of oxygen levels on three-way catalysts and ammonia storage levels on SCR catalysts.  In addition the potential for simultaneous measurements of stored ammonia on SCR-F applications in the presence of soot and ash are also presented.  The results indicate direct measurements of catalyst storage state, and resulting catalyst feedback control, via RF sensing to have significant potential for optimizing the combined engine and aftertreatment system in order to achieve even higher emissions conversion and minimize vehicle fuel consumption.

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