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Medientyp:
E-Artikel
Titel:
Measurement uncertainty of coulometric trace humidity sensors
Beteiligte:
Tiebe, Carlo;
Detjens, Marc;
Banach, Ulrich;
Hübert, Thomas
Erschienen:
Walter de Gruyter GmbH, 2018
Erschienen in:tm - Technisches Messen
Sprache:
Englisch
DOI:
10.1515/teme-2018-0031
ISSN:
0171-8096;
2196-7113
Entstehung:
Anmerkungen:
Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>Especially trace amounts of water vapour in gases can be reliably determined by coulometric trace humidity sensors. The principle of these sensors is based on water vapour absorption in a hygroscopic layer and its subsequent electrolytic decomposition. The calibration of sensors was performed in the humidity range, expressed as frost point temperature, from <jats:inline-formula id="j_teme-2018-0031_ineq_001_w2aab3b7b5b1b6b1aab1c17b1b1Aa">
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_teme-2018-0031_ineq_001.png" />
<m:math xmlns:m="http://www.w3.org/1998/Math/MathML">
<m:mo>−</m:mo>
<m:mn>30</m:mn>
<m:mspace />
<m:mi>°</m:mi>
<m:mi>C</m:mi>
</m:math>
<jats:tex-math>-30\hspace{0.1667em}^\circ \mathrm{C}</jats:tex-math>
</jats:alternatives>
</jats:inline-formula> to <jats:inline-formula id="j_teme-2018-0031_ineq_002_w2aab3b7b5b1b6b1aab1c17b1b3Aa">
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_teme-2018-0031_ineq_002.png" />
<m:math xmlns:m="http://www.w3.org/1998/Math/MathML">
<m:mo>−</m:mo>
<m:mn>80</m:mn>
<m:mspace />
<m:mi>°</m:mi>
<m:mi>C</m:mi>
</m:math>
<jats:tex-math>-80\hspace{0.1667em}^\circ \mathrm{C}</jats:tex-math>
</jats:alternatives>
</jats:inline-formula>. This range is equivalent to volume fractions smaller than 376 µL·L<jats:sup>−1</jats:sup>. Generated humidity was measured with coulometric sensors and a chilled dew point hygrometer that was used as reference. An empirical non-linear function was found between sensor signal and measured reference humidity. This function consists of two parameters with a measurement uncertainty. Both calibration parameters were checked by means of one-way analysis of variance. It showed that gas specific function can be used for humidity measurement in nitrogen, hydrogen, dinitrogen monoxide, compressed and synthetic air. It is possible to determine trace humidity in all tested gases with an expanded uncertainty less than 2.1 K (coverage factor <jats:inline-formula id="j_teme-2018-0031_ineq_003_w2aab3b7b5b1b6b1aab1c17b1b7Aa">
<jats:alternatives>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_teme-2018-0031_ineq_003.png" />
<m:math xmlns:m="http://www.w3.org/1998/Math/MathML">
<m:mi>k</m:mi>
<m:mo>=</m:mo>
<m:mn>2</m:mn>
</m:math>
<jats:tex-math>k=2</jats:tex-math>
</jats:alternatives>
</jats:inline-formula>) regarding frost point temperature.</jats:p>