Evaluation of a Model of Effective Thermal Conductivity in Soils by Power Averaging Partial Conductivities

ABSTRACT Background Soil thermal conductivity is a key factor for the soil heat balance and is widely used in many fields of soil science. However, it is necessary to measure thermal conductivity of soils that have different porosities and degrees of saturation. Aims and Methods In this study, a new approach based on the power mean is presented by calculating the effective thermal conductivity as the mean of the partial conductivities of soil components (typically of the solid, liquid, and gaseous phase). A function is proposed to describe the exponent p of the power mean exponent for all soil types. Results The model was evaluated using three extensive sets of measured data selected from the literature and was found to achieve comparable agreement with measured data to the best previous soil models. The study shows that the power mean approach is a suitable method for determining the effective conductivity of soils from the specific conductivities of their constituent phases. This approach can be used universally with all soil types, including organic soils. Conclusion The power mean approach is a valuable tool for studying and describing how soil structure influences effective thermal conductivity. Further research will demonstrate the applicability of this approach to investigating the anisotropy of thermal conductivity and its transferability to frozen soils. However, to increase the model accuracy, more knowledge about the specific thermal conductivity of the solid substances in the soil is required.