Thermal Conductivity of Compacted Snow

The accumulation of snow at the ground surface significantly influences heat transfer between soil and atmosphere due to its fairly low thermal conductivity compared to natural soils. The thermal conductivity of snow varies mostly with density, but also with crystalline structure and grain to grain contact. Human activities such as winter maintenance may also lead to dramatic changes in the snow properties. Compacted snow accumulated on the side of any infrastructure is much denser than fresh snow and conducts heat more easily. The aim of this paper is to study the thermal conductivity of compacted snow and to develop a suitable thermal conductivity model. The thermal conductivity values obtained in this study varies from 0.12 W/mK and 0.54 W/mK for porosities from 0.4 to 0.68 and for a temperature of -12°C. The semi-empirical thermal conductivity model developed for 2-phase porous materials by Côté and Konrad has been adapted to model the thermal conductivity of compacted snow. This model uses a single empirical parameter κ_2p to account for porosity and structure effects (thermal conductivity ratio between the solid phase and the fluid phase). The analysis results showed that the model successfully described the experimental data within the experimental range of porosity while respecting the physical limits of thermal conductivity of air and ice. Since temperature affects the thermal conductivity ratio between ice and air, the model proved to handle very well effect of temperature for other data of compacted snow from the literature. The very good agreement between the values of the κ_2p parameter found for this study and for data from the literature helped develop a simple means to account for temperature effects on the thermal conductivity of compacted snow.