Effect of reduced air pressure on soil thermal conductivity over a wide range of water content and temperature

2002 ◽  
Vol 53 (4) ◽  
pp. 599-606 ◽  
Author(s):  
T. Momose ◽  
T. Kasubuchi
Keyword(s):  
Thermal Conductivity ◽  
Water Content ◽  
Air Pressure ◽  
Soil Thermal Conductivity ◽  
Wide Range

The effect of soil temperature and soil water content on thermal properties in an artificial forestland and a natural regrowth grassland

2020 ◽  
Author(s):  
Tangtang Zhang ◽  
Xin Ma
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Condition ◽  
Soil Thermal Conductivity ◽  
Soil Thermal Properties ◽  
Increasing Temperature

<p>Soil temperature, soil water content and soil thermal properties were measured in an artificial forestland and a natural regrowth grassland from November in 2017 to July in 2019. The results show that the effects of soil temperature and soil water content on thermal properties are different in different soil condition. Soil thermal conductivity (K) and soil volumetric heat capacity (C) increase with increasing temperature in unfrozen period, but soil diffusivity (D) has no significant dynamic cycle and it almost keeps a constant level in a certain time. Soil thermal conductivity (K) decreases with increasing temperature during soil frozen period. The C and K increase with increasing soil water content in unfrozen period, while the D decrease with increasing soil water content.</p>

scholarly journals Experimental And Numerical Invetigation Of Dependence Of Soil Thermal Conductivity On Temperature Water Content, And Soil Texture

2021 ◽  
Author(s):  
Behnam Jowkar-Baniani
Keyword(s):  
Thermal Conductivity ◽  
Water Content ◽  
Soil Texture ◽  
Conductivity Data ◽  
Soil Thermal Conductivity ◽  
Pump System ◽  
Heat Pump System ◽  
Thermal Conductivity Data ◽  
Apparent Thermal Conductivity ◽  
The Impact

Comprehensive set of thermal conductivity data for a loam soil was generated, for temperature variations from 5ºC to 92ºC and water content variations from dry to saturation, and compared to two other soil textures. The results exhibited similar characteristics as those of the other textures, where a significant change in soil thermal conductivity was. Using the thermal conductivity data sets, a model representing heat and mass transfer in soil was used to study the apparent thermal conductivity due to vapour migration. In addition, a computer simulation of a ground source heat pump system was developed, where the experimental data was used to investigate the impact of water content and soil texture variation on the GSHP performance. It was observed that the GSHP energy consumption varied more prominently when the soil wetness varied from dryness to full saturation and less significantly when the soil type varied from coarse to finer texture.

scholarly journals An Empirical Model for Estimating Soil Thermal Conductivity from Soil Water Content and Porosity

2016 ◽  
Vol 17 (2) ◽  
pp. 601-613 ◽  
Author(s):  
Bing Tong ◽  
Zhiqiu Gao ◽  
Robert Horton ◽  
Yubin Li ◽  
Linlin Wang
Keyword(s):  
Thermal Conductivity ◽  
Water Content ◽  
Empirical Model ◽  
Large Scale ◽  
Soil Heat Flux ◽  
Soil Thermal Conductivity ◽  
New Model ◽  
Scale Models ◽  
Complex Models ◽  
Mean Square Errors

Abstract Soil thermal conductivity λ is a vital parameter for soil temperature and soil heat flux forecasting in hydrological models. In this study, an empirical model is developed to relate λ only to soil volumetric water content θ and soil porosity θs. Measured λ values for eight soils are used to establish the empirical model, and data from four other soils are used to evaluate the model. The new model is also evaluated by its performance in the Simple Biosphere Model 2 (SiB2). Results show that the root-mean-square errors (RMSEs; ranging from 0.097 to 0.266 W m−1 K−1) of the new model estimates of λ are lower than those (ranging from 0.416 to 1.006 W m−1 K−1) for an empirical model of similar complexity reported in the literature earlier. Further, with simple inputs and equations, the new model almost has the accuracy of other more complex models (RMSE of λ ranging from 0.040 to 0.354 W m−1 K−1) that require additional detailed soil information. The new model can be readily incorporated in large-scale models because of its simplicity as compared to the more complex models. The new model is tested for its effectiveness by incorporating it into SiB2. Compared to the original SiB2 λ model, the new λ model provides better estimates of surface effective radiative temperature and soil wetness. Owing to the newly presented empirical model’s requirement for simple, available inputs and its accuracy, its usage is recommended within large-scale models for applications where detailed information about soil composition is lacking.

Simultaneous use of newly adopted simple sensors for continuous measurements of soil moisture and salinity

Soil Research ◽  
2003 ◽  
Vol 41 (2) ◽  
pp. 309 ◽  
Author(s):  
F. Konukcu ◽  
A. Istanbulluoglu ◽  
I. Kocaman
Keyword(s):  
Thermal Conductivity ◽  
Moisture Content ◽  
Water Content ◽  
Water Table ◽  
Arid Regions ◽  
Sandy Loam ◽  
Clay Loam ◽  
Evaporation Chamber ◽  
Wide Range ◽  
Semi Arid

Methods available to measure salinity and moisture content in arid and semi-arid regions are limited because of the high salinities and very wide range of water contents (i.e. from saturation near the water table to air dry in the evaporation front). This paper is focused on the instrumentation employed in monitoring salt and moisture profiles in a column study which has wide applicability in salinity research. Experiments were conducted in a specially designed evaporation chamber which provided high evaporative demand as experienced in arid and semi-arid regions. Intensively instrumented soil columns with a constant shallow saline water table were used. Moisture content was measured by thermal conductivity and salinity by 4-electrode probe. In each case, instruments were manufactured specifically for the purpose in order to provide the desired degree of spatial resolution. Two soil types, sandy loam and clay loam, were used. Results indicated that thermal-conductivity probes measured water content over a wide range from saturation to 0.16 m3/m3 for clay loam and to 0.09 m3/m3 for sandy loam soil with great sensitivity (R2 > 0.95) and were unaffected by salt accumulation. The 4-electrode probes provided reliable measurements (R2 > 0.95) of the salinity of the soil solution for the range relevant to agricultural application. However, the accuracy of the probe decreased with the decreases in the water content after permanent wilting point.

scholarly journals Experimental And Numerical Invetigation Of Dependence Of Soil Thermal Conductivity On Temperature Water Content, And Soil Texture

2021 ◽  
Author(s):  
Behnam Jowkar-Baniani
Keyword(s):  
Thermal Conductivity ◽  
Water Content ◽  
Soil Texture ◽  
Conductivity Data ◽  
Soil Thermal Conductivity ◽  
Pump System ◽  
Heat Pump System ◽  
Thermal Conductivity Data ◽  
Apparent Thermal Conductivity ◽  
The Impact

Comprehensive set of thermal conductivity data for a loam soil was generated, for temperature variations from 5ºC to 92ºC and water content variations from dry to saturation, and compared to two other soil textures. The results exhibited similar characteristics as those of the other textures, where a significant change in soil thermal conductivity was. Using the thermal conductivity data sets, a model representing heat and mass transfer in soil was used to study the apparent thermal conductivity due to vapour migration. In addition, a computer simulation of a ground source heat pump system was developed, where the experimental data was used to investigate the impact of water content and soil texture variation on the GSHP performance. It was observed that the GSHP energy consumption varied more prominently when the soil wetness varied from dryness to full saturation and less significantly when the soil type varied from coarse to finer texture.

Analytical Determination of Soil Thermal Conductivity and Diffusivity

1988 ◽  
Vol 110 (4) ◽  
pp. 306-312 ◽  
Author(s):  
J. G. Ingersoll
Keyword(s):  
Thermal Conductivity ◽  
Moisture Content ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Porosity ◽  
Analytical Determination ◽  
Seasonal Temperature ◽  
Soil Thermal Conductivity ◽  
Dry Soil

A simple model has been developed that can be used to calculate the soil thermal conductivity and diffusivity on the basis of the following factors: soil porosity; soil water content; conductivity, specific heat, and density of the constituents of soil, i.e., solid matter, water, and air. The model assumes that the void space in soil can be presented by a combination of plane fissures, whose direction is either parallel to the heat flow or perpendicular to it. A coefficient introduced to account for this combination in the two directions can be estimated from measured data as a function of the soil water content. Moreover, it is assumed that air and moisture conduct heat across the fissures in parallel. It is found that soil conductivity and diffusivity increase relatively rapidly with a few percent addition of moisture to entirely dry soil. For instance, assuming a typical soil porosity of 40 percent we conclude that the ratio of soil diffusivities of saturated to dry soil is about four, while that of soild with 2.5 percent moisture content to dry soil is a little over two. That is to say, a small moisture addition to dry soil brings the diffusivity half way to its saturation value. Since soil always contains small amounts of moisture, this finding explains the fact that measured seasonal temperature damping factors in extreme humid and extreme arid climates differ by less than a factor of two even though the moisture content of the respective soils may differ by more than an order of magnitude.

scholarly journals A generalized model between thermal conductivity and matric suction of soils

2021 ◽  
Author(s):  
Sen Lu
Keyword(s):  
Thermal Conductivity ◽  
Soil Water ◽  
Land Surface ◽  
Matric Suction ◽  
Dew Point ◽  
Soil Thermal Conductivity ◽  
Pulse Technique ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Mean Square Errors

<p>Soil thermal conductivity (λ) is an important physical property in land surface parameterization. The soil thermal conductivity (λ) and matric suction of soil water (h, the negative of matric potential) relationship has been widely used in land surface models for estimating soil temperature and heat flux following the McCumber and Pielke (1981, MP81) λ-h model. However, few datasets are available for evaluating the accuracy and feasibility of the MP81 λ-h model under various soil and moisture conditions. In this study, we developed a new λ-h model and compared its performance with that of the MP81 model using measurements on 18 soils with a wide range of textures, water contents and bulk densities. The heat pulse technique was used to measure λ, and the suction table, micro-tensiometers, pressure plate device, and the dew point potentiometer were applied to obtain soil water retention curves at the appropriate suction ranges. In the range of pF (the common logarithm of h in cm)≤3, the λ-h relationships were highly nonlinear and varied strongly with soil texture and bulk density. In the dry range (i.e., pF > 3), there existed a universal λ-h relationship for all soil textures and bulk densities, and an exponential function was established to describe the relationship. Independent evaluations using λ-h data on five intact soil samples showed that the new model produced accurate λ data from pF values with root mean square errors (RMSE) with the range of 0.03–0.18Wm−1 K−1. While, large errors (RMSEs within 0.17–0.36Wm−1 K−1) were observed with λ estimates from the MP81 model. </p>

Sign in / Sign up

Export Citation Format

Share Document