Validation of Soil Thermal Conductivity Models

Wessolek, Gerd; Bohne, Klaus; Trinks, Steffen

doi:10.1007/s10765-022-03119-5

Cited by 14 publications

(14 citation statements)

References 31 publications

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“…The soil properties differ from those of previous validations [31][32][33][34] due to different sampling sites, all in Germany, and the combination of two measurement methods using needle sensors. The selection of empirical thermal conductivity models for validation was based on the work of Wessolek et al [34], with additional consideration of the model of Markert et al [27]. Therefore, the selection used in this study also differs from that of Dong et al [31] and Tarnawski et al [33].…”

Section: Introductioncontrasting

confidence: 59%

“…Table 3. Statistical analysis of the data base based on the work of Wessolek et al [34], with λ = thermal conductivity, θ = moisture content, ρ b = bulk density, S r = saturation and grain size distributions regarding clay (f Clay ), silt (f Silt ), and sand content (f Sand ). For this overview, the complete water content range is considered here.…”

Section: -2227 10mentioning

confidence: 99%

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A Practicable Guideline for Predicting the Thermal Conductivity of Unconsolidated Soils

Bertermann,

Rammler,

Wernsdorfer

et al. 2024

Soil Systems

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For large infrastructure projects, such as high-voltage underground cables or for evaluating the very shallow geothermal potential (vSGP) of small-scale horizontal geothermal systems, large-scale geothermal collector systems (LSCs), and fifth generation low temperature district heating and cooling networks (5GDHC), the thermal conductivity (λ) of the subsurface is a decisive soil parameter in terms of dimensioning and design. In the planning phase, when direct measurements of the thermal conductivity are not yet available or possible, λ must therefore often be estimated. Various empirical literature models can be used for this purpose, based on the knowledge of bulk density, moisture content, and grain size distribution. In this study, selected models were validated using 59 series of thermal conductivity measurements performed on soil samples taken from different sites in Germany. By considering different soil texture and moisture categories, a practicable guideline in the form of a decision tree, employed by empirical models to calculate the thermal conductivity of unconsolidated soils, was developed. The Hu et al. (2001) model showed the smallest deviations from the measured values for clayey and silty soils, with an RMSE value of 0.20 W/(m∙K). The Markert et al. (2017) model was determined to be the best-fitting model for sandy soils, with an RMSE value of 0.29 W/(m∙K).

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Section: Introductioncontrasting

confidence: 59%

Section: -2227 10mentioning

confidence: 99%

A Practicable Guideline for Predicting the Thermal Conductivity of Unconsolidated Soils

Bertermann,

Rammler,

Wernsdorfer

et al. 2024

Soil Systems

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“…The greater abundance in the spring reveals a more significant presence of water in the soil, coming from melting the snow cover. Different authors concluded that an increase in water content in soils results in an increase in the soils' thermal conductivity (e.g., Abu‐Hamdeh & Reeder, 2000; O'Donnell et al, 2009; Rasmussen et al, 2018; Schjønning, 2021; Wessolek et al, 2023). This could facilitate heat transmissivity from the surface to the ground.…”

Section: Discussionmentioning

confidence: 99%

Interannual variability of ground surface thermal regimes in Livingston and Deception islands, Antarctica (2007–2021)

de Pablo,

Ramos,

Vieira

et al. 2023

Land Degrad Dev

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The absence of vegetation in most ice‐free areas of Antarctica makes the soil surface very sensitive to atmosphere dynamics, especially in the western sector of the Antarctic Peninsula, an area within the limits of the permafrost zone. To evaluate the possible effects of regional warming on frozen soils, we conducted an analysis of ground surface temperatures (GSTs) from 2007 to 2021 from different monitoring sites in Livingston and Deception islands (South Shetlands archipelago, Antarctica). The analysis of the interannual evolution of the GST and their daily regimes and the freezing and thawing indexes reveals that climate change is showing impacts on seasonal and perennially frozen soils. Freezing Degree Days (FDD) have decreased while Thawing Degree Day (TDD) have increased during the study period, resulting in a balance that is already positive at the sites at lower elevations. Daily freeze–thaw cycles have been rare and absent since 2014. Meanwhile, the most common thermal regimes are purely frozen – F1 (daily temperatures < = −0.5°C), isothermal – IS (ranging between −0.5°C to +0.5°C), and purely thawed – T1 (> = +0.5°C). A decrease in F1 days has been observed, while the IS and T1 days increased by about 60 days between 2007 and 2021. The annual number of days with snow cover increased between 2009 and 2014 and decreased since then. The GST and the daily thermal regimes evolution point to general heating, which may be indicative of the degradation of the frozen soils in the study area.

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“…The flattening of the temperature profile after about 20 seconds is indicative of convection being present. and sensing elements arranged concentrically [28,29] or non-concentrically [20], as in the case of measuring the thermal conductivity of ceramics [19]. However, these designs have not been demonstrated at high temperatures within a fluid.…”

Section: Needle Probementioning

confidence: 99%

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

Ruth,

Merritt,

Munro

2024

Preprint

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This paper considers the necessary conditions for using a derivative of a transient hot wire (termed a needle probe) approach to measure electrically conducting fluids at high temperatures, especially molten halide salts. The focus is on the development of a new theory based on a multi-layer system necessary to ensure electrical isolation of electrical wires from the surrounding fluid. This includes the use of a thin annulus of fluid to minimize convective heat transfer modes within the fluid of interest, which was inspired by the concentric cylinder method. Good measurements require the following considerations: concentricity of the probe and surrounding crucible to ensure a consistent fluid gap, accounting for corrections for deviation of the model at early times, and modeling radiation heat transfer through transparent fluids. Uncertainties are larger than transient hot wire methods because of the deviations from experimental conditions that can easily match an analytical approximation. An appropriate estimation of the measurement uncertainty can be obtained through careful design of the instrumentation, thorough uncertainty analysis, and limiting the measurements to only the applicable thermal property ranges of the approach. The 1D model used to interpret measured temperature data has been shown to be reliable for thermal conductivity measurements ranging from at least 0.39 W/mK to 0.92 W/mK and for temperatures from 293-1023 K. The approach is used to present thermal conductivity data of the molten salts NaCl-KCl (51-49 mol%) and LiCl-NaCl (28-72 mol%).

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Validation of Soil Thermal Conductivity Models

Cited by 14 publications

References 31 publications

A Practicable Guideline for Predicting the Thermal Conductivity of Unconsolidated Soils

A Practicable Guideline for Predicting the Thermal Conductivity of Unconsolidated Soils

Interannual variability of ground surface thermal regimes in Livingston and Deception islands, Antarctica (2007–2021)

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

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