Error Analysis of Heat Pulse Method for Measuring Soil Heat Capacity, Diffusivity, and Conductivity

Kluitenberg, G. J.; Bristow, Keith L.; Das, Bhabani S.

doi:10.2136/sssaj1995.03615995005900030013x

Cited by 138 publications

(102 citation statements)

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“…The l of the soil is calculated based on temperature measurements and knowledge of the heat generated (~22.3 W m −1 ) during heating (1 min) and cooling (1 min) cycles (Decagon Devices, 2014). The calculations derive from a dual needle algorithm based on the line heat source analysis (Carslaw and Jaeger, 1959;Abramowitz and Stegun, 1972;Kluitenberg et al, 1993Kluitenberg et al, , 1995Bristow et al, 1994).…”

Section: Experimental Apparatusmentioning

confidence: 99%

Thermal Conductivity of Binary Sand Mixtures Evaluated through Full Water Content Range

Wallen

Smits

Sakaki

et al. 2016

Soil Science Soc of Amer J

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A soil's grain-size distribution affects its physical and hydraulic properties; however, little is known about its effect on soil thermal properties. To better understand how grain-size distribution affects soil thermal properties, specifically the effective thermal conductivity, a set of laboratory experiments was performed using binary mixtures of two uniform sands tightly packed with seven different mixing fractions over the full range of saturation. For each binary mixture, the effective thermal conductivity, l, capillary pressure, h c , and volumetric water content, q, were measured. Results demonstrated that the l-q relationship exhibited distinct characteristics based on the percentage of fine-and coarse-grained sands. We further compared measured l-q properties with independent estimates from two semi-empirical models (Campbell Model and Lu and Dong Model) to evaluate the models' applicability in relation to physically based parameters associated with changes in soil mixing (e.g., porosity and grain size). Both models were able to fit experimental data but to varying degrees based on the number of physically based parameters used. In general, model improvements are needed to capture the l-q relationship solely on physically based parameters.Abbreviations: SWRC, soil water retention curve. U nderstanding soil thermal properties is important to properly determine the impact of heat transfer on the distribution, circulation, and evaporation of water in soil. Heat transfer within soil influences micrometeorological phenomena (Hanks et al., 1967), engineering efforts such as cooling electronic devices with heat pipes and insulating buildings (Bussing and Bart, 1997;Sakaguchi et al., 2009;Moradi et al., 2015), agricultural production (Al Nakshabandi and Kohnke, 1965;Usowicz et al., 1996;Lipiec et al., 2007), and landmine detection efforts that rely on thermal contrast (e.g., Garcia-Padron et al., 2002;Martínez et al., 2004). Previous studies provide insight into the effect of soil moisture, temperature, and soil physical characteristics on soil thermal properties, specifically the effective thermal conductivity, l (W m -1 K -1 ; e.g., De Vries, 1963;Johansen, 1975;Hopmans and Dane, 1986;Ochsner et al., 2001;Tarnawski and Gori, 2002). However, to our knowledge, none of the studies to date has investigated the effect of mixing differently sized particles on controlling the l behavior under varying soil water contents (q, cm 3 cm -3 ). Knowledge of the l-q relationship for differently sized soil fractions is particularly important in many engineering applications such as soil borehole thermal energy storage (SBTES), landfill covers, and engineered material stabilization.Previous research provides strong evidence that l is affected by a wide range of parameters including q (e.g., Philip and de Vries, 1957;De Vries, 1963;Yadav and Saxena, 1977; Core Ideas• Thermal conductivity and water content relationship based upon mixtures are distinct.• Systematic change in particle fine fraction directly affects thermal cond...

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Section: Experimental Apparatusmentioning

confidence: 99%

Thermal Conductivity of Binary Sand Mixtures Evaluated through Full Water Content Range

Wallen

Smits

Sakaki

et al. 2016

Soil Science Soc of Amer J

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“…The volumetric specific heat is then determined from these parameters. The dual-needle algorithm was presented by Kluitenberg et al [18], and details about the design and working of the KD2-Pro device can be found in the operator's manual [19]. The uncertainty in the measurement of thermal conductivity and thermal diffusivity was calculated from repeated tests to be ±10%, and the uncertainty in the calculation of the specific heat was ±14%.…”

Section: Measurement Of Thermal Propertiesmentioning

confidence: 99%

Experimental Heat Transfer Study on Green Roofs in a Semiarid Climate during Summer

Issa

Leitch

Chang

2015

Journal of Construction Engineering

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An experimental study was conducted on green roofs under the semiarid summer climatic conditions of West Texas to investigate the effect of soil type, moisture content, and the presence of a top soil grass layer on the conductive heat transfer through the roof. Two soil types were investigated: uniform sand and local silt clay. Tests were also conducted on a control roof. A dual-needle heatpulse sensor was used to conduct thermal property tests on the soils. The tests reveal that unlike sand, the thermal conductivity of silt clay did not increase continuously with soil moisture. Better heat transfer conditions were achieved when the sand and silt clay roofs were watered to a water depth of 10 mm per day rather than double the amount of 20 mm per day. The roof with silt clay soil had the lowest fluctuation in inner temperature between daytime and nighttime. Green roofs with silt clay soil required more than twice the amount of soil moisture than green roofs with sand to achieve similar roof heat transfer rates. The best net heat flux gains for vegetated green roofs were 4.7 W/m 2 for the sand roof and 7.8 W/m 2 for the silt clay roof.

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“…The schematic view of a thermo-FDR sensor is shown in Fig. 2. Experiment Bristow et al (1994), Kluitenberg et al (1995), Noborio et al (1996), and Ren et al (1999Ren et al ( , 2003bRen et al ( , 2005 presented accurate measurements of soil thermal properties with 6-mm tube-to-tube spacing heat pulse sensors. Thus, the heat pulse design selected for the thermo-FDR sensor has already been verified in the literature.…”

Section: Sensor Designmentioning

confidence: 99%

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

Logsdon

Horton

2012

Soil Science Soc of Amer J

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Time domain reflectometry (TDR) is a well‐established electromagnetic technique used to measure soil water content. Time domain reflectometry sensors have been combined with heat pulse sensors to produce thermo‐TDR sensors. Thermo‐TDR sensors are restricted to having relatively short needles to accurately measure soil thermal properties. Short needle lengths, however, can limit the accuracy of the TDR measurement of soil water content. Frequency domain reflectometry (FDR) sensors are an alternative to TDR sensors that can provide an inexpensive measurement of soil water content. The objective of this study was to determine whether short FDR sensors can accurately measure soil water content. We designed and constructed a short FDR sensor. For four soil types across a range of water contents, temperatures, and salt contents, we measured soil dielectric spectra with the short FDR sensor. A vector network analyzer was used to obtain soil dielectric spectra in the 1‐MHz to 3‐GHz frequency range. The ideal frequency of a short FDR sensor is the frequency at which the permittivity is not altered by changing temperature or salt content. The 47‐ to 200‐MHz range was an ideal frequency range for measuring soil water content, and 70 MHz was the frequency least influenced by temperature and salt content. The short FDR sensor provided quick, continuous, stable, and cheap measurements of soil water content. Because of the promising performance of the short thermo‐FDR sensor in laboratory studies, sensors should be evaluated in future field studies.

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Error Analysis of Heat Pulse Method for Measuring Soil Heat Capacity, Diffusivity, and Conductivity

Cited by 138 publications

References 0 publications

Thermal Conductivity of Binary Sand Mixtures Evaluated through Full Water Content Range

Thermal Conductivity of Binary Sand Mixtures Evaluated through Full Water Content Range

Experimental Heat Transfer Study on Green Roofs in a Semiarid Climate during Summer

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

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