A Self-Calibrated Dual Probe Heat Pulse Sensor for In Situ Calibrating the Probe Spacing
A Self-Calibrated Dual Probe Heat Pulse Sensor for In Situ Calibrating the Probe Spacing
复制标题
用于现场校准探头间距的自校准双探头热脉冲传感器
DOI：
10.2136/sssaj2012.0434n
复制
发表时间：
2013-03-01
影响因子：
2.9
通讯作者：
Horton, Robert
中科院分区：
文献类型：
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作者：
Liu, Gang;Wen, Minmin;Horton, Robert
双探头热脉冲法是目前广泛应用的土壤热物性测量方法。然而，当该方法应用于现场时，温度探头和加热探头之间的距离（探头间距）可能由于探头偏转而改变，从而导致测量的土壤热容（c）的误差。我们开发了一种自校准的DPHP探针间距的原位校准，使用的温度探头与两个嵌入式热敏电阻（10毫米，在纵向方向上分开）。对砂土和细砂样品的实验结果表明，该方法可以显著减小探头偏转引起的误差。如果定义σ为探头偏离垂直方向的倾角，对于0.8° < θ < 0.9°的向内偏转，c的误差在-8.1 ~-14.3%之间;经现场校准后，c的误差在-0.1 ~-4.3%之间。对于3.2° < θ < 3.5°的外挠度，c的误差在22.9 ~ 38.8%之间，经现场标定后，误差减小到-3.8 ~-7.8%。这种新的DPHP设计可以应用于现场，以减少由探头偏转引起的误差。
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.