Thermal effect of heat transfer process of deep borehole heat exchangers on surrounding rock and soil

Jia Linrui, Cui Ping, Fang Liang and Fang Zhaohong

2021.01.20

Analyses the temperature response and variation of the rock and soil around the buried pipe under different heating conditions using a numerical heat transfer model. Proposes the definition of the thermal influence radius. Studies the thermal influence radii of single borehole and multiple-borehole buried pipes on the surrounding rock and soil at different running times and heating loads. The study shows that when the borehole depth is 2 000 m, the largest thermal influence radius occurs at the depth of 1 750 m. For the deep borehole heat exchangers with 3×3 boreholes, recommends over 100 m of the borehole spacing, and the nominal heat loss rate is less than 5%.