Increasing the efficiency of a geothermal heat exchanger

Currently, the fastest growing option for using geothermal energy is ground source heat pumps. To ensure conditions for ideal thermal contact between the elements of the system under consideration, moistened sand backfills are used. The use of moistened sand as backfill will inevitably be associated with the presence of phase transitions and changes in heat transfer mechanisms in the design of the geothermal heat exchanger. The possibility of increasing the efficiency of a geothermal heat exchanger by changing the thermal conductivity of its structural elements and the presence of phase transitions in them is shown. It has been established that taking into account the presence of a phase transition in the sand backfill leads to an increase in heat inflows by 16.13-21.81 % depending on the temperature of the heated rocks and the volumetric humidity of the backfill. The significant influence of the non- stationary processes of transfer and temperatures of hot rocks on the intensification of heat transfer in the system under consideration is shown.