Investigation of Soil for Shallow Geothermal: field tests and laboratory measurements for the determination of thermal properties for the design of combined abstraction of heat and storage of solar energy

Abstract

Soil thermal properties determination for shallow geothermal systems is vital since they constrain the design and optimisation of the system for either heat extraction or storing airos. Hence, the testing of the ground becomes an important aspect. This subsoil understanding can be achieved by literature estimations, laboratory tests, in-situ tests and numerical simulations.

VIA University College owns in its facilities three100m depth different BHE (Single U, Double U and Coaxial) and the equipment to execute thermal conductivity measurements in the laboratory and in-situ TRT. So, in this dissertation a three way approach to the obtaining of the ground thermal conductivity has been executed: i) a priori estimation from literature; ii) laboratory test using the Thermal Needle Probe Procedure and iii) in-situ TRT. The results have been compared. In addition, from the TRT the borehole resistance can be calculated and an evaluation of the three BHE has been made.