Energy geostructure: experimental and numerical modelling of thermal behaviour and interaction within the city underground

Development of energy geostructures into cities induces proximity interaction. When placed in a groundwater flow, advection effect will increase heat pump efficiency and avoid multiyear thermal shift. Yet, it also creates a thermal plume that can interact with downstream structures. In order to study these interactions, this article presents an experimental study conducted within the Sense City experimental facility, and a numerical hydraulic-thermal coupled model, developed with the FEM software CESAR-LCPC to extrapolate the experimental results. Both experimental and numerical studies allowed us to understand and estimate thermal interaction within a group of piles. Thermal interactions are strongly directional and aligned with the water flow, effects of multiple piles are cumulative and decrease within the distance. Simulation of heat pump efficiency show the benefits of underground water flow and thermal washing, increasing efficiency coefficient above 4 and erasing thermal cluster effect.