Estimation method of soil thermal physical parameters based on thermal response test of ground heat exchangers

According to the measured inlet and outlet water temperature and flow rates, estimates the thermal conductivity of soil, thermal resistance in hole and heat capacity per unit volume using linear and cylindrical heat source analytical models and one-dimensional numerical model respectively. Presents two and three-parameter estimation methods. Three-parameter estimation method can estimate the thermal conductivity, thermal resistance in hole and heat capacity per unit volume at the same time, but the calculation time is too long, and the requirement of the computer memory is higher. Two-parameter estimation method can obtain reasonable results through searching thermal conductivity and thermal resistance in hole, the heat capacity per unit volume can be obtained by using the correlative equation, and the calculation time is less. The results based on the two parameter estimation method show that the result using one-dimensional numerical model is closer to the actual value.