Heated Fiber Optic Distributed Temperature Sensing: A Dual‐Probe Heat‐Pulse Approach

Benítez-Buelga, Javier; Sayde, Chadi; Rodríguez-Sinobas, Leonor; Selker, John S.

doi:10.2136/vzj2014.02.0014

Cited by 37 publications

(41 citation statements)

References 43 publications

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“…Unfortunately, due to the construction of DTS cables, the contact and thermal resistance between the armored fiber‐optic cable and surrounding soil can be worse than that for SPHP. The DPHP approach has also been applied to an AHFO‐DTS system (Benítez‐Buelga et al, ). However, as stated above, the DPHP is very sensitive to the spacing ( r ) between the heat and sensor probes, and keeping two long cables (1 m to 10 km) parallel at an exact fixed distance can be problematic for the AHFO‐DTS.…”

Section: Application Of the Hp Methods In Unfrozen And Frozen Soilsmentioning

confidence: 99%

Development and Application of the Heat Pulse Method for Soil Physical Measurements

Dyck

Horton

et al. 2018

Reviews of Geophysics

125

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Accurate and continuous measurements of soil thermal and hydraulic propertiesare required for environmental, Earth and planetary science, and engineering applications, but they are not practicallyobtained by steady-state methods. The heat pulse (HP) method is a transient method for determinationof soil thermal properties and a wide range of other physical properties in laboratory and field conditions. The HP method is based on the line-heat source solution of the radial heat flow equation. This literature review begins with a discussion of the evolution of the HP method and related applications, followed by the principal theories, data interpretation methods and their differences. Important factors for HP probe construction are presented. The properties determined in unfrozen and frozen soilsare discussed, followed by a discussion of limitations and perspectives for the application of this method. The paper closes with a brief overview of future needs and opportunities for further development and application of the HP method.Keywords thermal properties, thermal conductivity, thermal resistivity, heat capacity, thermal diffusivity, thermal inertia, dual probe heat pulse, thermal probe, hot-wire method, fiber optics, distributed temperature sensing (DTS), thermo-time/frequency domain reflectometry (thermo-TDR, thermo-FDR), soilwater content, ice content, frozen soils, instrumentation DisciplinesAgricultural Science | Agriculture | Hydrology | Soil Science Comments This is a manuscript of an article published as He, Hailong, Miles F. Dyck, Robert Horton, Tusheng Ren, Keith L. Bristow, Jialong Lv, and Bingcheng Si. "Development and application of the heat pulse method for soil physical measurements." Reviews of Geophysics (2018) This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1029/2017RG000584 © 2018 American Geophysical Union. All rights reserved.Development and application of the heat pulse method for soil physical properties in laboratory and field conditions. The HP method is based on the line-heat source solution of the radial heat flow equation. This literature review begins with a discussion of the evolution of the HP method and related applications, followed by the principal theories, data interpretation methods and their differences. Important factors for HP probe construction are presented. The properties determined in unfrozen and frozen soilsare discussed, followed by a discussion of limitations and perspectives for the application of this method. The paper closes with a brief overview of future needs and opportunities for further development and application of the HP method.

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Section: Application Of the Hp Methods In Unfrozen And Frozen Soilsmentioning

confidence: 99%

Development and Application of the Heat Pulse Method for Soil Physical Measurements

Dyck

Horton

et al. 2018

Reviews of Geophysics

125

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“…Several minutes or hours of alternate or direct current voltage are needed to produce this heating, and the electric cable is typically integrated into the same fibre cable. The use of a separate electrical cable kept at a constant distance from the optical fibre was investigated with interesting results [123][124][125]. Nonetheless, it is required that the optical fibre and the electrical cable be separated by a constant distance all along the cable-a condition not so easy to achieve in practical applications.…”

Section: Distributed Temperature Sensing For Soil Levees and Embankmentsmentioning

confidence: 99%

“…The mechanism is similar to that exploited for leakage detection: different levels of soil moisture lead to different thermal conductivity, and in turn to a differential temperature behaviour for heating and cooling cycles (Figure 8b) or for seasonal temperature variations. In particular, it was shown that the accuracy of the active method [120,123,129] was sufficient to qualitatively assess the local degree of saturation and the volumetric heat capacity. Nonetheless, optical fibre sensing systems provide lesser accuracy than traditional probes, such as dielectric acquameters or electrical time domain reflectometers: for this reason, Sayde et al [130] proposed to integrate the temperature deviation over time.…”

Section: Distributed Temperature Sensing For Soil Levees and Embankmentsmentioning

confidence: 99%

“…Although most of the applications and papers dealt with short-term measurement campaigns [107,137] or experiments in physical models [123,125,138,139], there are some examples testifying years-long measurement campaigns [100,106,140]-all employing Raman-DTSs. For example, within the framework of the project IJkdijk, Beck et al [106] analysed the data collected over a measurement period of one year to test the reliability of long-term data analysis approaches.…”

Section: Distributed Temperature Sensing For Soil Levees and Embankmentsmentioning

confidence: 99%

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A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

2017

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Featured Application: Distributed fibre optic sensors for geo-hydrological applications: a comprehensive review about methodology, weaknesses, and strengths.Abstract: Distributed optical fibre sensing, employing either Rayleigh, Raman, or Brillouin scattering, is the only physical-contact sensor technology capable of accurately estimating physical fields with spatial continuity along the fibre. This unique feature and the other features of standard optical fibre sensors (e.g., minimal invasiveness and lightweight, remote powering/interrogating capabilities) have for many years promoted the technology to be a promising candidate for geo-hydrological monitoring. Relentless research efforts are being undertaken to bring the technology to complete maturity through laboratory, physical models, and in-situ tests. The application of distributed optical fibre sensors to geo-hydrological monitoring is here reviewed and discussed, along with basic principles and main acquisition techniques. Among the many existing geo-hydrological processes, the emphasis is placed on those related to soil levees, slopes/landslide, and ground subsidence that constitute a significant percentage of current geohazards.

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“…The AHFO‐DTS is similar to the SPHP in theory, but uses a fiber‐optic cable to measure soil temperature and thus could potentially extend the temperature, thermal properties, and θ measurement scales from a point to an intermediate landscape scale. A DPHP‐based AHFO‐DTS system was also tested to measure C and θ by installing two or more fiber‐optic cables paralleling each other, which has the same drawbacks as the DPHP (Benítez‐Buelga et al, 2014). To further develop an SPHP‐based AHFO‐DTS, there is a need to extend the measurements from λ to C and θ for the SPHP.…”

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confidence: 99%

Single‐Probe Heat Pulse Method for Soil Water Content Determination: Comparison of Methods

Cheng

et al. 2016

Vadose Zone Journal

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Core Ideas Six methods to obtain soil water content by single probe are presented and compared. Errors of estimated soil water content by six methods increase with water content. Heating duration affects soil water content estimation errors. Four of the six methods are probe dependent but can be easily calibrated. Each method works for some soils, and combining different methods is a solution. The estimation of soil thermal conductivity (λ) using the single‐probe heat pulse (SPHP) method is well known, but estimation of soil water content (θ) using the SPHP is poorly understood. In this study, we examined six methods—λ, normalized cumulative temperature increase (TNcum), normalized maximum temperature increase (TNmax), and the reciprocals of each—for θ estimation using the SPHP. The temperature response curves of four soils at different θ were measured following 600‐s heat pulses with heating strengths of about 6 W m−1, from which λ, TNcum, and TNmax values were determined. The maximum measurement errors of these three methods were 0.11 m3 m−3 for the coarse sand and 0.01 m3 m−3 for the fine sand, sandy loam, and silty clay, except for 0.05 m3 m−3 for the fine sand by the λ(θ) method. The predicted θ from all of the λ, TNcum, and TNmax methods agreed well with that from the oven‐dry method for all soils with the exception of the TNcum(θ) and TNmax(θ) methods for the coarse sand for θ > 0.20 m3 m−3. The measurement errors and θ predictions of the 1/λ(θ) method were similar to that of the TNcum(θ) and TNmax(θ) methods, and that of the 1/TNcum(θ) and 1/TNmax(θ) methods were similar to that of the λ(θ) method. Because each of the six methods worked well for only some soils, improved estimations were obtained when the λ(θ) method was combined with the 1/TNcum(θ) [or 1/TNmax(θ)] method for coarse‐textured soils and the 1/λ(θ) method was combined with the TNcum(θ) [or TNmax(θ)] method for fine‐textured soils.

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Heated Fiber Optic Distributed Temperature Sensing: A Dual‐Probe Heat‐Pulse Approach

Cited by 37 publications

References 43 publications

Development and Application of the Heat Pulse Method for Soil Physical Measurements

Development and Application of the Heat Pulse Method for Soil Physical Measurements

A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

Single‐Probe Heat Pulse Method for Soil Water Content Determination: Comparison of Methods

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