Thermo-mechanical performance of a geothermal pile system for re-harvesting the energy loss through the basement of a building in cold regions

ABSTRACT: Geothermal energy piles are bi-functional structural elements that are used to support the building, as well as to operate as geo-heat exchangers for shallow geothermal energy systems. However, broad application of thermo-active piles is hindered due to the underground thermal imbalance. We used a numerical thermal analysis for the example of an institutional building located in Winnipeg (MB) to assess the thermal balance of the ground. The heat exchanger probes inlet temperature of the geothermal energy foundation was chosen to meet the underground thermal balance. In addition, using Thermo-Mechanical (TM) modeling, the impacts of thermal loads on mechanical performance of the geothermal pile foundation was studied. The results showed that the axial stress effective on the pile increased by 8% due to thermal loads. Therefore, to consider thermo-active piles as an alternative for buildings energy supply, further considerations should be made to keep the axial stress induced by thermal loads within the admissible range.