Numerical Simulation of the Freezing Process in Geothermal Boreholes Using Solar Heat Injection

Ground thermal energy as a clean and sustainable energy source has received significant attention lately. Several strategies and hybrid configurations have been proposed to harvest geothermal energy for air conditioning and industrial purposes. The possibility of moist soil freezing in the vicinity of borehole tubes is known to be the source of several benefits and difficulties. The high storage capacity during the freezing process and the structural damage are the major advantages and disadvantages of the thawing phenomenon, respectively. In the present study, the numerical simulation of the freezing process around the U-tube configuration of boreholes accompanied by the solar energy injection as the auxiliary heat source is investigated. Lower values of cold stream temperature result in the higher amount of recovered heat, while increasing the injected heat temperature intensifies the heat regaining. Moreover, the energy absorbed by the ice layer around the tube is directly related to the cold stream temperature.