Influence of Different Design Parameters on the Shifted Load Behavious of Borehole Heat Exchanger Array System

To contribute to the goal of carbon neutralization, the borehole heat exchanger (BHE) system is widely applied to use geothermal energy for buliding cooling and heating. In practical application, there will be thermal interaction between BHEs, which will lead to the phenomenon of shifted load. In this work, a comprehensive numerical model with 5 U-type BHEs has been established by OpenGeoSys coupled with TESPy to clarify the impact of multiple factors on the the shifted load bahavious of BHEs. The influence of different arrangements and interboreholes spacing on the shifted load bahavious of BHEs are studied. The results show that the heat load gradually moves from the center to the edge of the boreholes by analyzing the shifted load of the characteristic borehole heat exchanger. The maximum shifted load of the central characteristic borehole of the horizontal arrangement is much smaller than that of the square arrangement, and the proportion of the shifted thermal load(PSTL) range of the square arrangement is also the largest among the three arrangements, which indicates that the denser the arrangements, the greater the impact of shifted load on the BHE. After changing the inter-boreholes spacing of the square arrangement, for the central borehole, the maximum change of the shifted load rate at D = 3m is close to twice that at D = 6m, which can be seen that with the increase of the inter-borehole spacing, this shifted load phenomenon is weakened, which provides a reference for the design of BHEs in the future.