Journal cover Journal topic
Journal of Sensors and Sensor Systems An open-access peer-reviewed journal
J. Sens. Sens. Syst., 6, 237-246, 2017
https://doi.org/10.5194/jsss-6-237-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular research article
14 Jun 2017
High-temperature CO / HC gas sensors to optimize firewood combustion in low-power fireplaces
Binayak Ojha, Navas Illyaskutty, Jens Knoblauch, Muthu Raman Balachandran, and Heinz Kohler Institute for Sensor and Information Systems (ISIS), Karlsruhe University of Applied Sciences, 76133 Karlsruhe, Germany
Abstract. In order to optimize firewood combustion in low-power firewood-fuelled fireplaces, a novel combustion airstream control concept based on the signals of in situ sensors for combustion temperature, residual oxygen concentration and residual un-combusted or partly combusted pyrolysis gas components (CO and HC) has been introduced. A comparison of firing experiments with hand-driven and automated airstream-controlled furnaces of the same type showed that the average CO emissions in the high-temperature phase of the batch combustion can be reduced by about 80 % with the new control concept. Further, the performance of different types of high-temperature CO / HC sensors (mixed-potential and metal oxide types), with reference to simultaneous exhaust gas analysis by a high-temperature FTIR analysis system, was investigated over 20 batch firing experiments (∼ 80 h). The distinctive sensing behaviour with respect to the characteristically varying flue gas composition over a batch firing process is discussed. The calculation of the Pearson correlation coefficients reveals that mixed-potential sensor signals correlate more with CO and CH4; however, different metal oxide sensitive layers correlate with different gas species: 1 % Pt / SnO2 designates the presence of CO and 2 % ZnO / SnO2 designates the presence of hydrocarbons. In the case of a TGS823 sensor element, there was no specific correlation with one of the flue gas components observed. The stability of the sensor signals was evaluated through repeated exposure to mixtures of CO, N2 and synthetic air after certain numbers of firing experiments and exhibited diverse long-term signal instabilities.

Citation: Ojha, B., Illyaskutty, N., Knoblauch, J., Balachandran, M. R., and Kohler, H.: High-temperature CO / HC gas sensors to optimize firewood combustion in low-power fireplaces, J. Sens. Sens. Syst., 6, 237-246, https://doi.org/10.5194/jsss-6-237-2017, 2017.
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Short summary
A novel combustion airstream control concept has been developed based on in situ sensors for combustion temperature, residual oxygen concentration and residual un-combusted CO / HC components. The implementation of this control concept allows for a large reduction in toxic gas emissions by up to 80 % compared to hand-operated furnaces. A stable long-term CO / HC sensor for such an application is not available; thus, the long-term sensor signal stability of different CO / HC sensors is studied.
A novel combustion airstream control concept has been developed based on in situ sensors for...
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