| Title | Thermal and Dielectric Behavior of Loess Soils Under Effective Stress |
|---|---|
| Authors | Henok HAILEMARIAN, Frank WUTTKE, Thomas SCHICHT, Sandro JOHN |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Thermal conductivity; complex dielectric permittivity, effective stress, HF-EM |
| Abstract | Thermal conductivity plays a vital role in the conductive heat transfer analysis of many engineering applications, such as the operation of small and large scale seasonal thermal energy storage and geothermal energy systems. Hence, accurate determination of the thermal conductivity of the heat storage medium, which in the form of solid sensible heat storage materials can vary from cemented porous media to a wide variety of natural soils, is vital in the design and operation of such systems. One promising technique, which can be used to accurately estimate the thermal conductivity of large porous media deposits is via the measurement of dielectric data (such as complex dielectric permittivity) using non-destructive high frequency electromagnetic (HF-EM) techniques. To do so, having a strong correlation between the two controlling heat transfer and electromagnetic parameters (i.e. thermal conductivity and complex dielectric permittivity, respectively) under different hydro-mechanical conditions is necessary. In this study, the correlation between the thermal conductivity and complex dielectric permittivity of a loess soil is investigated experimentally by performing steady state thermal conductivity and HF-EM tests under applied effective stress of up to 400 kPa. The results show a strong correlation between the two parameters, indicating a possibility of using dielectric measurements for obtaining thermal conductivity of porous media. |