Estimating thermal conductivity of frozen soils from air‐filled porosity

Abstract

AbstractSoil thermal conductivity (λ) is an important thermal property for environmental, agricultural, and engineering heat transfer applications. Existing λ models for frozen soils are complicated to use because they require estimates of both liquid water content and ice content. This study introduces a new approach to estimate λ of partially frozen soils from air‐filled porosity (na), which can be determined by using an oven‐drying method. A λ and na relationship was established based on measurements for 28 partially frozen soils. A strong exponential relationship between λ and na was found (with R2 of 0.82). Independent tests on 10 partially frozen soils showed that the exponential λ–na model produced reliable λ estimates with a RMSE of 0.319 W m−1 K−1, which was smaller than those of two widely used λ models for partially frozen soils. The λ–na model is easier to use than existing models, because it requires fewer parameters. Note that the λ‐na model ignores the effect of temperature on λ of frozen soils and is most applicable to soil at temperatures of at least −4 °C.