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- Leong, W.H., et al.
(author)
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Inter-particle contact heat transfer model : An extension to soils at elevated temperatures
- 2005
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In: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 29:2, s. 131-144
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Journal article (peer-reviewed)abstract
- A simple 'inter-particle contact heat transfer' model for predicting effective thermal conductivity of soils at moderate temperatures (0-30°C) has been extended up to 90°C. The extended model accounts for latent heat transport by water vapour diffusion in soil air above the permanent wilting point, below that point, the soil thermal conductivity is approximated by linear interpolation without latent heat effect. By and large the best results are obtained when the latent heat is used only in the 'self consistent approximation' model with an overall root mean square error of 35% for all soils under consideration or 26% when excluding volcanic soils. This option can also be applied to moderate temperatures at which the enhanced heat transfer is negligibly small. Copyright © 2005 John Wiley & Sons, Ltd.
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| 2. |
- Tarnawski, V.R., et al.
(author)
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Inter-particle contact heat transfer in soil systems at moderate temperatures
- 2002
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In: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 26:15, s. 1345-1358
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Journal article (peer-reviewed)abstract
- An inter-particle contact heat transfer model for evaluating soil thermal conductivity is analysed with respect to soils, representing different textural classes, exposed to moderate temperatures ranging from 15 to 30°C. This model is a combination of a self-consistent approximation model, enhanced with an inter-particle contact heat transfer correction coefficient. For dry and saturated soils, this coefficient is defined as a ratio of a soil harmonic mean thermal conductivity of solid and fluid (air or water) phases, to the average thermal conductivity of soil solid grains. For unsaturated soils, we assume a linear interpolation of the correction coefficient between absolutely dry and saturated states, with a Kersten function (Ke) as a proportional factor. The strongest impact of the correction coefficient (maximum reduction of heat transfer) is observed for coarse soils below a critical value of saturation degree (Sr-cr-corresponds to Ke ? 0) followed by medium and fine soils. For Sr > Srcr, the reduction of heat transfer gradually diminishes as Sr approaches 1 (i.e. saturated state). Soil texture, soil specific surface area, porosity and mineralogical composition (particularly quartz content) are important factors influencing the heat transfer correction coefficient. Their influence appears to be more substantial at the lower half of the wetness range (Sr < 0.5). Simulation results from the new enhanced model closely follow experimental data. © 2002 John Wiley and Sons, Ltd.
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