LOCIE has two test platforms for studying heat transfer in the near subsoil in the presence of geothermal exchangers.
The bench for studying geothermal baskets in real-life conditions comprises a set of 5 geothermal baskets, each 1 m in diameter, buried between 1 and 3 m below ground level, instrumented with temperature probes and connected to a 4 kW water-to-water heat pump. This system enables us to study the influence of soil type and the distance between baskets, as well as the soil's ice absorption and solicitation mode.
This bench has been fitted with electrodes to study changes in soil temperature and moisture disturbed by heat extraction or injection through a geothermal basket.
The bench for studying geothermal baskets under controlled conditions consists of an insulated tank thermally guarded on its side wall. The tank is filled with a model soil (calibrated silica sand). The upper and lower surfaces of the sand are respectively subjected to imposed temperature conditions reproducing the usual boundary conditions. This device reproduces at 1/10th scale the temperature and humidity conditions encountered in sub-surface conditions. It also reproduces precipitation and the presence of a stagnant water table, the level of which is fixed.
The sand is instrumented with thermocouples and humidity measurements. Electrodes are also installed to study the soil's thermo-hydric evolution over time. Three thermostatic baths are used to thermally control the tank and the geothermal basket within it.