Estimating Soil Thermal Conductivity by Weighted Average Models with Soil Solids as a Continuous Medium

Abstract

In an attempt to further simplify and to refine the modeling of soil thermal conductivity (λ), two novel weighted average models (WAMs) were developed in which soil solids represent the continuous phase. In the first model, WAMs-1, the continuous phase consists of two distinctive minerals groups (quartz and compounded remaining soil minerals), while air and water are treated as dispersed components. In the second model, WAMs-2, all soil minerals are compounded and considered the continuous phase, while air and water are dispersed components. In contrast to de Vries’ original WAM with two continuous phases (soil air or soil water), the proposed models are very simple due to the following assumptions: using soil solids as a single continuous medium lead to eliminating the discontinuity of thermal conductivity when switching between soil air and soil water as continuous medium, and using the thermal conductivity of dry air simplifies a complex expression for an apparent thermal conductivity of humid soil air. Both models were successfully calibrated and validated using 39 Canadian Field Soil database and 3 Standard Sands and were successfully applied to 10 Chinese soils.

Thermophysical Properties of Bentonite–Sand/Fly Ash-Based Backfill Materials for Underground Power Cable

“…Moreover, the assessment of representative value of thermal conductivity of soil solids (λ s ) is very di cult, without knowing the mineralogy of soil [51]. Therefore, Tarnawski et al [52] re ned the thermal conductivity modeling of soil based on weighted average model (WAM) of soil solids as the continuous medium considering the two distinct mineral groups, i.e., quartz and other minerals, due to fact that higher thermal conductivity of quartz (7.7 Wm − 1 K − 1 ) with respect to other minerals (2.2 Wm − 1 K − 1 ) [44].…”