Intensification of heat gain to geothermal heat exchangers

The need to ensure reliable thermal contact between the elements of geothermal heat exchangers and the environment leads to the use of a variety of backfills. Various materials are used as backfills. This could be ordinary cement or even materials with phase transitions. The use of advanced construction materials and materials with phase transitions significantly increases the high capital costs when constructing wells with geothermal heat exchangers. It is proposed to use a common and inexpensive material as backfill. This is moistened sand. The solution to the problem was obtained using the finite difference method. An implicit difference scheme and a special algorithm were used. The coordinate step was no more than 10 mm. The volumetric moisture content of the sand backfill varied from initial (5 %) to 25 %. It was limited by open porosity. The initial temperature, in the considered solution region, was taken to be equal to the temperature of the heated rocks 298.15-373.15 K. The temperature of the pumped energy carrier was 278.15 K. The work established that an increase in the humidity of the sand backfill leads to an increase in heat inflows by 4-12.5 %. 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.