Inner heat source model with heat and moisture transfer in soil around the underground heat exchanger

This paper presents an inner heat source model of underground heat exchanger based on the heat and mass transfer theory in soil. A number of factors such as moisture movement in soil, soil type, and soil property were taken into account in the model. The underground heat exchanger was simplified as the equivalent inner heat source term in the model. The software of Autough2 was used to conduct the numerical simulations. And the paper presents the analyses on the influences of different soil properties and different operation modes on the underground temperature field around the single U-vertical underground heat exchanger.