GeoTh: An Experimental Laboratory Set-Up for the Measurement of the Thermal Conductivity of Granular Materials

Abstract

GeoTh is a new, simple, efficient, flexible, low-cost experimental laboratory apparatus. These features make it an excellent technological tool for measuring the thermal conductivity of granular materials, e.g., soils, sand, silt, clay or artificial composites. In particular, a configuration based on the one-dimensional heat conduction in steady-state regime was designed, built, and assembled to determine the thermal conductivity of the samples. In addition, we developed two user-friendly codes; the first for acquisition of the technical data (time series of air temperature; samples temperatures; and heat power); and the second relative to the elaboration of collected data and the calculation of the physical and thermophysical parameters of each analyzed sample (porosity, bulk density, % of water saturation, thermal conductivity, thermal diffusivity). The developed apparatus allows us to temporarily carry out measurements from one to six samples either in ambient conditions or at constant temperature. The robustness of the system has been tested by analyzing and measuring numerous materials in different conditions. We also performed several tests by varying the water content (between 0% and 100% water saturation) for sandy and silty-sand samples to calibrate and test the robustness of the system as well as for verifying the repeatability of the analytical data. Finally, the obtained thermal conductivity values are compared with other dataset proposed in the literature, showing a good fit.

Keywords

• experimental thermal conductivity set-up
• steady state method
• water saturation
• granular material