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A Self‐Calibrated Dual Probe Heat Pulse Sensor for In Situ Calibrating the Probe Spacing
Author(s) -
Liu Gang,
Wen Minmin,
Chang Xupei,
Ren Tusheng,
Horton Robert
Publication year - 2013
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2012.0434n
Subject(s) - in situ , calibration , remote sensing , environmental science , pulse (music) , dual (grammatical number) , materials science , optics , physics , geology , meteorology , detector , quantum mechanics , art , literature
Dual probe heat pulse method (DPHP) is a popular method for measuring soil thermal properties. However when this method is applied in the field, the distance between the temperature probe and the heating probe (probe spacing) may change due to probe deflection, and thus cause error in measured heat capacity ( c ) of soil. We developed a self‐calibrated DPHP for in situ calibration of probe spacing, using a temperature probe with two imbedded thermistors (10 mm apart in the longitudinal direction). Experimental results for sand and fine sand samples indicate that this method can significantly reduce error caused by the probe deflection. If we define σ as the inclination angle of probe deviation from the vertical direction, for inward deflection with 0.8° < θ < 0.9°, the error in c is between –8.1 and –14.3%; after in situ calibration, it is between –0.1 and –4.3%. For outward deflection with 3.2° < θ < 3.5°, the error in c is in the range from 22.9 to 38.8%; after in situ calibration, the error reduces to from –3.8 to –7.8%. This new DPHP design may be applied in the field for reducing error caused by probe deflection.