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

Abstract

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.

Keywords:

• Physical modelling
• numerical modelling
• geothermal energy
• energy geostructures
• interactions

Acknowledgement

We address our thanks to Bruno Regnicoli Benitez and Mahamadou Soumaoro for their work as intern on this subject.

Disclosure Statement

The authors report there are no competing interests to declare.

Data Availability

The participants of this study did not give express written consent for their data to be shared publicly, therefore due to the sensitive nature of the research, supporting data is only available upon request to the corresponding author.

Notes

1 High-Density PolyEthylene (plastic).

2 By its position, it doesn’t interact with the group of piles and doesn’t affect its behaviour.

3 The samples were prepared at the same compaction level as the soil in Sense City.

4 Diffusion Transitoire Non Linaire, Nonlinear Transient Diffusion.

Additional information

Funding

This work was supported by self funding from University Gustave Eiffel.