Haibing Shao1, Shuang Chen1,2, Wanlong Cai3, Francesco Witte4, Xuerui Wang5, Olaf Kolditz1,2
1Helmholtz Zentrum für Umweltforschung - UFZ, Deutschland; 2Dresden University of Technology; 3Xi'an Jiaotong University; 4Flensburg University of Applied Sciences; 5University Hannover
When a large Borehole Heat Exchanger (BHE) array is coupled with heat pumps to provide building cooling and heating, thermal interaction may occur among the BHEs. This work take advantage of a well-monitored BHE array project in Leicester, UK. The monitoring data shows a slight increase in the circulation fluid temperature over a period of 2 years. Using the planning of the Leicester project, numerical models is constructed based on the Open-Source modeling platform OpenGeoSys, and it is successfully verified against the monitored temperature trend. Various numerical scenarios were further simulated, to reveal the response of the BHE array system under heavier thermal load. Modelling results show that the heat injection rate on the central BHEs is gradually shifted towards those located at the edge. When looking at the over-all system behavior, a linear correlation is found between the working fluid temperature change and the amount of the accumulated heat injected into the subsurface. This finding suggests that a calculation procedure can be set up to estimate the circulation temperature change in the designing phase, in order to assure the long-term sustainability of the large BHE array.
