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Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations
Department of Functional Materials, Bayreuth Engine Research Center (BERC), University of Bayreuth, 95440 Bayreuth, Germany
Ford Research and Advanced Engineering, Dearborn, MI 48124, USA
Andrea Groß formerly Andrea Geupel.
* Author to whom correspondence should be addressed.
Received: 26 December 2011; in revised form: 22 February 2012 / Accepted: 23 February 2012 / Published: 1 March 2012
Abstract: The accumulating-type (or integrating-type) NOx sensor principle offers two operation modes to measure low levels of NOx: The direct signal gives the total amount dosed over a time interval and its derivative the instantaneous concentration. With a linear sensor response, no baseline drift, and both response times and recovery times in the range of the gas exchange time of the test bench (5 to 7 s), the integrating sensor is well suited to reliably detect low levels of NOx. Experimental results are presented demonstrating the sensor’s integrating properties for the total amount detection and its sensitivity to both NO and to NO2. We also show the correlation between the derivative of the sensor signal and the known gas concentration. The long-term detection of NOx in the sub-ppm range (e.g., for air quality measurements) is discussed. Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed.
Keywords: dosimeter; signal derivative; sensitivity NO/NO2; operation temperature; measurement range adaption; response rise/recovery time; exhaust gas sensor
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Groß, A.; Beulertz, G.; Marr, I.; Kubinski, D.J.; Visser, J.H.; Moos, R. Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations. Sensors 2012, 12, 2831-2850.
Groß A, Beulertz G, Marr I, Kubinski DJ, Visser JH, Moos R. Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations. Sensors. 2012; 12(3):2831-2850.
Groß, Andrea; Beulertz, Gregor; Marr, Isabella; Kubinski, David J.; Visser, Jaco H.; Moos, Ralf. 2012. "Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations." Sensors 12, no. 3: 2831-2850.