scholarly journals Estimation of Thermal Diffusivity for Greenhouse Soil Temperature Simulation

2020 ◽  
Vol 10 (2) ◽  
pp. 653
Author(s):  
Jizhang Wang ◽  
Wee Fong Lee ◽  
Peter P. Ling
Keyword(s):  
Heat Transfer ◽  
Thermal Diffusivity ◽  
Phase Shift ◽  
Soil Temperature ◽  
Temperature Data ◽  
Greenhouse Soil ◽  
Sinusoidal Model ◽  
Soil Thermal Diffusivity ◽  
Different Depths ◽  
Energy Balance Models

In greenhouse energy balance models, the soil thermal parameters are important for evaluating the heat transfer between the greenhouse air and the soil. In this study, the soil thermal diffusivity was estimated from greenhouse soil temperature data using the amplitude, phase-shift, arctangent, logarithmic, and min-max methods. The results showed that the amplitude method and the min-max method performed well in estimating the soil thermal diffusivity. The obtained soil thermal diffusivity was input into a sinusoidal model to determine the greenhouse soil temperature at different soil depths. For greenhouse applications, the daily average soil temperature at different depths was predicted according to the temperature at the surface and the annual mean soil temperature. The model was validated using soil temperature data from summer and winter, when the greenhouse was cooled and heated, respectively.

scholarly journals Soil Apparent Thermal Diffusivity Estimated by Conduction and by Conduction–Convection Heat Transfer Models

2016 ◽  
Vol 18 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Bing Tong ◽  
Zhiqiu Gao ◽  
Robert Horton ◽  
Linlin Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Diffusivity ◽  
Phase Shift ◽  
Soil Temperature ◽  
Water Flux ◽  
Convection Heat Transfer ◽  
Vertical Gradient ◽  
Temperature Phase ◽  
Maximum Value ◽  
Amplitude Attenuation

Abstract Soil heat transfer is complex, and conduction-alone models may not always perform well in estimating soil apparent thermal diffusivity. Soil apparent thermal diffusivity is related to soil temperature change propagation rates. Soil temperature data collected at the Tazhong station in China were used to examine the characteristics of soil apparent thermal diffusivity determined by three different algorithms and the sum of vertical gradient of soil apparent thermal diffusivity and apparent water flux density . The results showed that 1) soil apparent thermal diffusivity obtained with a conduction–convection algorithm had a better agreement with soil apparent thermal diffusivity obtained with a phase algorithm than with soil apparent thermal diffusivity obtained with an amplitude algorithm except for the case of = 0; 2) when > 0, , and when < 0, ; 3) for a given soil temperature phase shift, increased (decreased) with increasing logarithmic amplitude attenuation when the phase shift was larger (smaller) than the logarithmic amplitude attenuation, reached a maximum value when the phase shift equaled the logarithmic amplitude attenuation, and increased with increasing logarithmic amplitude attenuation; and 4) for a given logarithmic amplitude attenuation, decreased with increasing phase shift and increased (decreased) with increasing phase shift when the phase shift was larger (smaller) than times the logarithmic amplitude attenuation. These mathematical conclusions were also confirmed with field data.

scholarly journals Comparison of six algorithms to determine the soil thermal diffusivity at a site in the Loess Plateau of China

2009 ◽  
Vol 6 (2) ◽  
pp. 2247-2274 ◽  
Author(s):  
Z. Gao ◽  
L. Wang ◽  
R. Horton
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Loess Plateau ◽  
One Dimensional ◽  
Boundary Temperature ◽  
Soil Thermal Diffusivity ◽  
Thermal Diffusivities ◽  
Upper Boundary

Abstract. Soil thermal diffusivity is a crucial physical parameter that affects soil temperature. Six prevalent algorithms to calculate soil thermal diffusivity are inter-compared by using soil temperature data collected at the depths of 0.05 m and 0.10 m at a bare site in the China Loess Plateau from DOY 201 through DOY 207 in 2005. Five of the six algorithms (i.e., Amplitude, Phase, Arctangent, Logarithm, and Harmonic or HM algorithms) are developed from the traditional one-dimensional heat conduction equation. The other algorithm is based on the one-dimensional heat conduction-convection equation which considers the vertical heterogeneity of thermal diffusivity in soil and couples thermal conduction and convection processes (hereinafter referred to as the Conduction-convection algorithm). To assess these six algorithms, we (1) calculate the soil thermal diffusivities by using each of the algorithms, (2) use the soil thermal diffusivities to predict soil temperature at the 0.10 m depth, and (3) compare the estimated soil temperature against direct measurements. Results show that (1) HM algorithm gives the most reliable estimates among the traditional five algorithms; and (2) generally, the Conduction-convection algorithm provides the second best estimates. Among all of the algorithms, the HM algorithm has the best description of the upper boundary temperature with time, but it only includes conduction heat transfer in the soil. Compared to the HM algorithm, the Conduction-convection algorithm has a less accurate description of the upper boundary temperature, but by accounting for the vertical gradient of soil diffusivity and the water flux density it includes more physics in the soil heat transfer process. The Conduction-convection algorithm has potential application within land surface models, but future effort should be made to combine the HM and Conduction-convection algorithms in order to make use of the advantages of each.

scholarly journals Soil thermal diffusivity estimated from data of soil temperature and single soil component properties

2013 ◽  
Vol 37 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Quirijn de Jong van Lier ◽  
Angelica Durigon
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Spatial Organization ◽  
Amplitude Ratio ◽  
Subsurface Layer ◽  
Phase Lag ◽  
Soil Thermal Diffusivity ◽  
Soil Component ◽  
Soil Components

Under field conditions, thermal diffusivity can be estimated from soil temperature data but also from the properties of soil components together with their spatial organization. We aimed to determine soil thermal diffusivity from half-hourly temperature measurements in a Rhodic Kanhapludalf, using three calculation procedures (the amplitude ratio, phase lag and Seemann procedures), as well as from soil component properties, for a comparison of procedures and methods. To determine thermal conductivity for short wave periods (one day), the phase lag method was more reliable than the amplitude ratio or the Seemann method, especially in deeper layers, where temperature variations are small. The phase lag method resulted in coherent values of thermal diffusivity. The method using properties of single soil components with the values of thermal conductivity for sandstone and kaolinite resulted in thermal diffusivity values of the same order. In the observed water content range (0.26-0.34 m³ m-3), the average thermal diffusivity was 0.034 m² d-1 in the top layer (0.05-0.15 m) and 0.027 m² d-1 in the subsurface layer (0.15-0.30 m).

scholarly journals Effect of Phyisco-chemical Parameters on the Thermal Diffusivity and Soil Heat Flux over Ayadi, Ondo State, Nigeria

2020 ◽  
Vol 9 (1) ◽  
pp. 1-5
Author(s):  
K. D. Adedayo Adedayo
Keyword(s):  
Heat Flux ◽  
Thermal Diffusivity ◽  
Physical Properties ◽  
Soil Temperature ◽  
Air Temperature ◽  
Soil Heat Flux ◽  
Dry Season ◽  
Wet Season ◽  
Different Depths ◽  
Ondo State

This study assesses the effect of some soil physical properties on the thermal diffusivity and soil heat flux over Ayadi in Ondo State, Nigeria. Physical properties of the soil at different depths were determined using laboratory techniques. In-situ measurement of air temperature and surface soil temperature were carried out. The phase lag method was used to determine the thermal diffusivity of the soil, while the subsoil heat flux was determined from values obtained for the thermal diffusivity. The result showed that the subsoil heat flux values during the dry season ranged between 0.58 and 52.84 W/m2, while that of the wet season ranged between -0.77 and 98.50 W/m2. The average thermal diffusivity values at the different depths had values between 0.74 × 10-7 and 238.7 × 10-7 m2/s for the dry season, while the wet season had a range of 1.97 × 10-7 to 238.7 × 10-7 m2/s. Keywords: soil moisture content, air temperature, soil temperature, soil heat flux, thermal diffusivity.

Estimation from Soil Temperature of Soil Thermal Diffusivity and Heat Flux in Sub-surface Layers

2015 ◽  
Vol 158 (3) ◽  
pp. 473-488 ◽  
Author(s):  
Kedong An ◽  
Wenke Wang ◽  
Yaqian Zhao ◽  
Wenfeng Huang ◽  
Li Chen ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Surface Layers ◽  
Soil Thermal Diffusivity
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