Soil thermal behaviour: Characterization by the Hot Wire Method and numerical application

The rising concern revealed by society in the last years, regarding the energetic sustainability of the planet, has become the main driver for the development of new techniques to explore energy that contribute to a decrease in greenhouse gases emission. The Ground Source Energy Systems are currently one of the most applied renewables technologies used for heating and cooling all over Europe, with its basic principle laying in the consideration of the soil as a heat source or sink. The study of the thermal transfer mechanisms and thermal properties that characterize the soil thermal behavior are therefore crucial in the evaluation and design of more efficient systems. This work presents the thermal characterization of a sandy soil and a set of numerical analysis relative to the thermal soil-pile foundation interaction. The laboratory work consists on a series of thermal conduction tests by carried out in an apparatus conceived for that purpose. The results interpretation is based on the Hot Wire Method. The influence of factors such as the void ratio on the thermal conductivity is analysed. The numerical analyses, only taking into account heat conduction, has the main purpose of presenting the main variables involved in a thermoactive pile operation for dry and totally saturated conditions as well as the possible temperature range involved