Modeling soil thermal conductivities over a wide range of conditions

Abstract

This paper presents a new method to seamlessly calculate thermal conductivity for various soil conditions, from loose to compact, organic to mineral, fine to coarse textured, frozen to unfrozen, and dry to wet. The soil is considered as a multi-phase system, containing air, water (liquid, ice), and particles finer (organic matter, minerals) and coarser (gravel) than 2 mm. The new method extends the general portability of the earlier Johansen (1975) method, and this generalization was fine-tuned empirically with data from soil, gravel, and peat drawn from recent and older literature, for frozen and unfrozen conditions from −30 to 30 • C, and for variable moisture and bulk density conditions from dry to saturated. Scatter plots between measured conductivity and best-fitted calculations consistently followed a straight 1:1 correspondence, with R 2 values generally above 0.90. The new method was then used to re-interpret thermal conductivity data involving wettable and non-wettable soils, in situ field measurements, and snow.Résumé : Cet article présente une nouvelle méthode d'évaluer la conductivité thermique de divers sols, qu'ils soient compacts ou meubles, organiques ou minéraux, de texture fine ou grossière, gelés ou non, et secs ou humides. Pour ce faire, le sol est considéré comme un système à phases multiples contenant de l'air, de l'eau (liquide, glace) et formé de particules de diamètre inférieur (matière organique, minéraux) ou supérieur (graviers) à 2 mm. Cette nouvelle méthode étend le champ d'application de la méthode de Johansen (1975) et a été raffinée empiriquement grâce à des données de sols, de graviers et de tourbe tirées de la littérature récente et ancienne, caractérisant des sols gelés et non gelés, de −30 à +30 • C, de densité et d'humidité très variées, de sèche à saturée. Les diagrammes de dispersion obtenus démontrent une correspondance étroite (1:1) entre les conductivités mesurées et calculées au meilleur ajustement, avec des valeurs de R 2 généralement supérieures à 0,90. Cette nouvelle méthode est ensuite appliquée pour réinterpréter des données de conductivité thermique de sols hydrophiles, hydrophobes, de mesures in situ et de neige.

Accumulated snow layer influence on the heat transfer process through green roof assemblies

“…The sensible heat conduction may be dominant, but with a few restrictions, as described by the previous study of Kaempfer [14]. Therefore, the current study indicates validity of the snow conductivity calculated as the effective heat conductivity (EHC) of snow that aggregates: (1) conductivity through the ice matrix and the pore space, (2) the latent heat release and gain by recrystallization, and (3) the convective heat exchange between ice and pore air.…”

Thermal properties of engineered barriers for a Canadian deep geological repository

“…Comparisons are plotted in Figure 13a and 13b. The Balland and Arp (2005) model had relatively higher COV for the bentonite-based materials (COV >39%) and lower for dense backfill with COV, which also significantly improved for the optimized parameters (COV between 4.3-9.5%). Balland and Arp (2005) Outcomes of the statistical analysis of the thermal conductivity models allows for some recommendations to be drawn.…”

“…The Balland and Arp (2005) model had relatively higher COV for the bentonite-based materials (COV >39%) and lower for dense backfill with COV, which also significantly improved for the optimized parameters (COV between 4.3-9.5%). Balland and Arp (2005) Outcomes of the statistical analysis of the thermal conductivity models allows for some recommendations to be drawn. The number of thermal conductivity measurements performed for this study (206 total), allow for statistics to be evaluated on predictive models as well as soil-specific calibrations.…”

Improving a plot-scale methane emission model and its performance at a northeastern Siberian tundra site

“…The thermal diffusivity is estimated based on the volumetric heat capacity and thermal conductivity. An improved method for estimating soil thermal conductivity from generic soil composition data (Balland and Arp, 2005) has replaced the calculation in the previous version of Peatland-VU, which was based on Williams and Smith (1991). This adjustment allows the model to simulate a more realistic active layer depth due to a better approximation of the thermal conductivity of the frozen soil.…”