Thermophysical properties of low-potential geothermal energy system hole fillers

Ground heat exchangers placed in specially drilled holes are used to remove a low-potential thermal energy of the ground. To ensure effective operation of these devices, a filler is used to fill the remaining empty space in the hole. At present, bentonite is recommended as the filler but this material is hard to access for many Russian regions and due to this fact, it costs a lot. In this paper, an alternative material is offered as a hole filler of ground heat exchangers - water-sand mortar. The material is selected on the basis of the analysis of its thermal properties and its comparison with the bentonite properties.