Study of varying characteristics of the heat transfer in ground heat exchanger under operating conditions

Through the theoretical calculation of thermal resistance of rock-soil and the numerical simulation of ground heat exchanger, obtains the variation relationship between the temperature difference and heat transfer of ground heat exchanger. Theoretical analysis and field measurement results show that the time-varying characteristic of the heat transfer of ground heat exchanger can be divided into three segments — rapidly varying segment, moderate varying segment and linear varying segment. Obtains the fitted formulas for heat transfer per running metre and temperature difference in moderate and linear varying segments separately.