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LED-absorption-QEPAS sensor for biogas plants

: Köhring, M.; Böttger, S.; Willer, U.; Schade, W.

Postprint (3.7 MByte; PDF; )

Sensors. Online journal 15 (2015), Nr.5, S.12092-12102
ISSN: 1424-8220
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer HHI ()

A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors; it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors.