Evaluation of Multi-Boreholes Heat Exchanges Based on Optimization Model

Yong, Li; Lian, Hui-Liang; Peng, Fu-Sheng; Han, Xu; Liu, Hai-Bo; Zhang, Ludan

doi:10.1142/9789813220294_0087

Cited by 1 publication

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“…It can be assumed that in areas with more developed karst fractures, the abundant groundwater flow would drag the heat inside the rock, and soil migrates along with it [10]. Therefore, an appropriate optimal placement of a borehole group can be adopted to improve the overall heat transfer capacity of ground heat exchangers [11,12]. Some large-scale projects need a large number of boreholes to meet the load requirement, with up to more than 1000 boreholes in some project cases.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment

Ran,

Peng,

Tian

et al. 2024

Energies

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Fractured rock mass is extensively distributed in Karst topography regions, and its geological environment is different from that of the quaternary strata. In this study, the influences on geological environment induced by the construction and operation of a large-scale borehole group of ground source heat pumps are analyzed by a thermo-hydro-mechanical (THM) coupling numerical model. It was found that groundwater is redirected as the boreholes can function as channels to the surface, and the flow velocity in the upstream of borehole group is higher than those downstream. This change in groundwater flow enhances heat transfer in the upstream boreholes but may disturb the original groundwater system and impact the local geological environment. Heat accumulation is more likely to occur downstream. The geo-stress concentration appears in the borehole area, mainly due to exaction and increasing with the depth. On the fracture plane, tensile stress and maximum shear stress simultaneously occur on the upstream of boreholes, inducing the possibility of fracturing or the expansion of existing fractures. There is a slight uplift displacement on the surface after the construction of boreholes. The correlations of the above THM phenomena are discussed and analyzed. From the modeling results, it is suggested that the consolidation of backfills can minimize the environmental disturbances in terms of groundwater redirection, thermal accumulation, occurrence of tensile stress, and possible fracturing. This study provides support for the assessment of impacts on geological environments resulting from shallow geothermal development and layout optimization of ground heat exchangers in engineering practices.

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Section: Introductionmentioning

confidence: 99%