Assessment of some soil thermal conductivity models via variations in temperature and bulk density at low moisture range
- Authors: Mahdavi S.M.1, Neyshabouri M.R.1, Fujimaki H.2
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Affiliations:
- Department of Soil Science
- Arid Land Research Center
- Issue: Vol 49, No 8 (2016)
- Pages: 915-925
- Section: Soil Physics
- URL: https://journals.rcsi.science/1064-2293/article/view/223475
- DOI: https://doi.org/10.1134/S1064229316080068
- ID: 223475
Cite item
Abstract
Simulation of heat transfer in soil under steady and unsteady situations requires reliable estimate of soil thermal conductivity (λ) at varying environmental conditions. In the current work several soil thermal conductivity predicting models including I) de Vries, II) Campbell, III) combined de Vries and Campbell and IV) de Vries-Nobre were evaluated for the four soils of coarse sand, sandy loam, loam and clay loam textured at varying in temperature and bulk density at low moisture range. Thermal conductivities measured by the cylindrical probe method served as the reference for models assessment. Results showed that approximately same thermal conductivities obtained by the five methods at low moisture range (θ ≤ 0.05 m3/m3). Also the de Vries and de Vries-Campbell models produced accurate than Campbell and de vries-Nobre models. The accuracy of the two models increased with soil compaction but decreased with temperature rise. Campbell model showed more reliability at higher (311.16 and 321.16 K) temperatures; but its accuracy declined with soil compaction in current work. It seems that assuming needle shape for the soil particles is far away from the reality whereas assuming spherical shapes may be more realistic and produced more satisfactory prediction of thermal conductivity. The compaction would alter particle arrangement and may increase the contact area of particles; and then make them behave more or less spherical shape.it seems thermal conductivity in solid particles increase via increasing in temperature. Since a modified mineral shape factor, gm, was developed as a combination between sphere and needle according to geometric mean particle diameter as well as bulk density and temperature as modifying factors. This factor increased the accuracy of de Vries-Nobre model up to 10.37%. Regarding nonlinear regression model, moisture content, bulk density, temperature and quartz content demonstrated significant effect on soil thermal conductivity in our investigation.
About the authors
Seyed Mohamad Mahdavi
Department of Soil Science
Author for correspondence.
Email: mohamad.mahdavi64@gmail.com
Iran, Islamic Republic of, Tabriz
Mohammad Reza Neyshabouri
Department of Soil Science
Email: mohamad.mahdavi64@gmail.com
Iran, Islamic Republic of, Tabriz
Haruyuki Fujimaki
Arid Land Research Center
Email: mohamad.mahdavi64@gmail.com
Japan, Tottori