Heat transfer in horizontal ground heat exchangers

The mathematical model of a horizontal ground heat exchanger was presented. The model was based on a one-dimensional equation of the transient heat conduction with an internal source of heat. The model was correctly verified by comparison of computational results and experimental measurements presented in literature. Temporal changes of the ground surface temperature and rates of heat transferred from the ground to the working fluid and between the ground surface and the environment were determined. Moreover, temporal variations of the average temperature of the subsurface layer of the ground were determined. It was found that after about 10 years of operation, the ground temperature reaches a cyclic steady state. Thermal calculations concerning the ground under natural conditions were also presented.