An analytical study of a two‐layer transient thermal conduction problem as applied to soil temperature surveys

Geophysics ◽  
1992 ◽  
Vol 57 (2) ◽  
pp. 306-312
Author(s):  
T. H. Larson ◽  
A. T. Hsui
Keyword(s):  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Thermal Conduction ◽  
Lower Layer ◽  
Soil Layer ◽  
Shallow Water Table ◽  
Transient Thermal ◽  
Mathematical Requirement ◽  
Spreadsheet Software ◽  
Layer Problem

The soil temperature survey is an inexpensive exploration method in groundwater and geothermal resource investigations. In its simplest form, temperatures measured in shallow holes are analyzed to deduce variations in material properties. Typical interpretation schemes are based on simple, one‐layer solutions to the Fourier conduction equation using the annual solar cycle as a surface heat source. We present a solution to the more complicated two‐layer problem that can be computed using inexpensive personal computers and spreadsheet software. The most demanding mathematical requirement is the ability to manipulate a [Formula: see text] matrix. Testing the solution over a range of thermal diffusivity values expected in common soils and rocks reveals that the solution is very sensitive to variations in the thermal diffusivity of the surface layer and to the depth of the interface with the lower layer. When the boundary to the lower layer is less than about 10 m deep, a soil temperature survey is expected to be sensitive to the diffusivity variations in the lower layer. Because variations in shallow thermal properties often can be significant, this two‐layer method should be useful in areas with distinct shallow layering, (e.g., where there is a shallow water table or a thin soil layer).

On: “An analytical study of a two-layer transient thermal conduction problem as applied to soil temperature surveys” by T. H. Larson and A. T. Hsui (February 1992 GEOPHYSICS, p. 306–312)

Geophysics ◽  
1992 ◽  
Vol 57 (12) ◽  
pp. 1644-1645
Author(s):  
Virgil J. Lunardini
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Thermal Conduction ◽  
Thermal Response ◽  
Periodic Surface ◽  
Ground Temperatures ◽  
Ground Conditions ◽  
Thermal Properties Of Materials ◽  
Properties Of Materials ◽  
Transient Thermal

This paper presents a solution to the two‐layer conduction problem, a problem which has already been solved exactly and published (Lachenbruch, 1959; Lunardini, 1981). In fact the three‐layer solution is also available, (Lachenbruch, 1959). Unfortunately the Larson and Hsui paper uses an incorrect boundary condition for the energy flow continuity between the layers; this refers to the last equation after equation (3), or equation (A-20) of their paper. The temperature gradient must be multiplied by the thermal conductivity, not the thermal diffusivity as the paper has done. The results obtained in the paper are only valid if the heat capacities ρc of the two layers are equal. However, few soils have the same heat capacity, as can be seen from the thermal properties of materials often encountered in geotechnical situations, given in Table 1. Thus, a second parameter is required for interpreting ground temperatures: the ratio of the thermal conductivities of the two layers. The interpretation given to the effects of only the thermal diffusivity ratios is then open to question. Calculations of the same ground conditions as used by Larsen and Hsui, with the same diffusivity ratios but with realistic thermal conductivity ratios, give significantly different temperature predictions. Of course, the general conclusions of the paper on the profound effect of layering on the thermal response of soils to periodic surface temperatures are still true.

Analysis the Influence of the Thermal Diffusivity of the Soil around Buried Pipe on Soil Physical Property

2013 ◽  
Vol 805-806 ◽  
pp. 552-556
Author(s):  
Ying Xu ◽  
Xiao Yan Liu
Keyword(s):  
Temperature Field ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Temperature Drop ◽  
Physical Property ◽  
Field Soil ◽  
Buried Pipeline ◽  
Buried Pipe ◽  
Soil Physical Property ◽  
Natural Temperature

In chilliness area, the temperature drop of oil in buried pipeline is affected by soil temperature field, and the thermal diffusivity is one of the main of physical property the soil, which affects the temperature drop of oil directly. This paper introduced the test principle of the thermal diffusivity of soil, and researched the influence of thermal diffusivity of soil on the soil physical property, such as soil natural temperature field, soil frozen days, depth of freezing and temperature delay, which can offer theory support for the calculation of hot oil temperature drop in buried pipeline.

scholarly journals Transient thermal conduction with variable conductivity using the Meshless Local Petrov–Galerkin method

2016 ◽  
Vol 272 ◽  
pp. 676-686 ◽  
Author(s):  
N.P. Karagiannakis ◽  
G.C. Bourantas ◽  
A.N. Kalarakis ◽  
E.D. Skouras ◽  
V.N. Burganos
Keyword(s):  
Galerkin Method ◽  
Thermal Conduction ◽  
Transient Thermal ◽  
Variable Conductivity

scholarly journals Effect of Postsowing Compaction on Cold and Frost Tolerance of North China Plain Winter Wheat

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Caiyun Lu ◽  
Chunjiang Zhao ◽  
Xiu Wang ◽  
Zhijun Meng ◽  
Jian Song ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Soil Temperature ◽  
North China Plain ◽  
North China ◽  
Growth Parameters ◽  
Soil Layer ◽  
Frost Tolerance ◽  
Cold Weather ◽  
Shoot Number ◽  
Soil Temperatures

Improper postsowing compaction negatively affects soil temperature and thereby cold and frost tolerance, particularly in extreme cold weather. In North China Plain, the temperature falls to 5 degrees below zero, even lower in winter, which is period for winter wheat growing. Thus improving temperature to promote wheat growth is important in this area. A field experiment from 2013 to 2016 was conducted to evaluate effects of postsowing compaction on soil temperature and plant population of wheat at different stages during wintering period. The effect of three postsowing compaction methods—(1) compacting wheel (CW), (2) crosskill roller (CR), and (3) V-shaped compacting roller after crosskill roller (VCRCR)—on winter soil temperatures and relation to wheat shoot growth parameters were measured. Results showed that the highest soil midwinter temperature was in the CW treatment. In the 20 cm and 40 cm soil layer, soil temperatures were ranked in the following order of CW > VCRCR > CR. Shoot numbers under CW, CR, and VCRCR treatments were statistically 12.40% and 8.18% higher under CW treatment compared to CR or VCRCR treatments at the end of wintering period. The higher soil temperature under CW treatment resulted in higher shoot number at the end of wintering period, apparently due to reduced shoot death by cold and frost damage.

Thermal Diffusivity of Multi-Walled Carbon Nanotubes Dispersed in Oleic Acid

2012 ◽  
Vol 21 ◽  
pp. 125-130 ◽  
Author(s):  
Alex Junior de Freitas Cabral ◽  
Clascídia Aparecida Furtado ◽  
Cristiano Fantini ◽  
Petrus Alcantara Jr.
Keyword(s):  
Carbon Nanotubes ◽  
Oleic Acid ◽  
Thermal Diffusivity ◽  
Thermal Lens ◽  
Theoretical Expression ◽  
Thermal Lens Spectrometry ◽  
Multi Walled Carbon Nanotubes ◽  
Spectrometry Technique ◽  
Transient Thermal ◽  
Walled Carbon Nanotubes

Suspensions of oleic acid with carbon nanotubes were prepared. Using a thermal lens experimental setup, the thermal diffusivity of oleic acid in presence of multi-walled carbon nanoparticles with different concentrations was measured. The results show that, the thermal diffusivity increases with the increase of nanotubes concentration, enhancing the thermal diffusivity in the solution. Modification in the thermal diffusivity as function of quantity of carbon nanotubes was investigated, for a constant volume of oleic acid 10 mL. The diffusivities were obtained by using the thermal lens spectrometry technique. The characteristic time constant of the transient thermal lens was obtained by fitting the theoretical expression to the experimental data.

scholarly journals Characteristics of Soil Moisture and Evaporation under the Activities of Earthworms in Typical Anthrosols in China

2020 ◽  
Vol 12 (16) ◽  
pp. 6603
Author(s):  
Li Ma ◽  
Ming’an Shao ◽  
Tongchuan Li
Keyword(s):  
Soil Temperature ◽  
Soil Water ◽  
Agricultural Development ◽  
Soil Layer ◽  
Soil Surface ◽  
Soil Evaporation ◽  
Water Evaporation ◽  
Soil Columns ◽  
Soil Surface Temperature ◽  
Water Holding

Earthworms have an important influence on the terrestrial ecological environment. This study assesses the effect of different earthworm densities on soil water content (SWC) and evaporation in a laboratory experiment. Four earthworm densities (0 no-earthworm, control [C]; 207 earthworms m−2, low density [LDE]; 345 earthworms m−2, medium density [MDE]; and 690 earthworms m−2, high density [HDE]) are tested in soil columns. Results show that cumulative evaporation occurs in the decreasing order of densities: C (98.6 mm) > LDE (115.8 mm) > MDE (118.4 mm) > HDE (124.6 mm). Compared with the control, earthworm activity decreases cumulative soil evaporation by 5.0–20.9%, increases soil temperature to 0.46 °C–0.63 °C at 8:00, and decreases soil temperature to 0.21 °C–0.52 °C at 14:00 on the soil surface. Temperature fluctuations reduce with increasing earthworm densities. A negative correlation is found between cumulative soil evaporation and earthworm density (R2 = 0.969, p < 0.001). Earthworms significantly (p < 0.05) decrease the surface SWC loss (0–20 cm) soil layer but increase the subsoil SWC loss (60–100 cm) by adjusting the soil temperature and reducing soil water evaporation. Earthworm activities (burrows, casts…) improve the soil water holding ability by adjusting soil temperature and reducing soil water evaporation. Thus, the population quantity of earthworms may provide valuable ecosystem services in soil water and heat cycles to save water resources and realize sustainable agricultural development.

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