A three-dimensional full-scale model for predicting the performance of deep-buried ground heat exchanger considering groundwater flow

It is critical to precisely determine the performance of deep-buried ground heat exchangers involving different geological layers in engineering projects of the geothermal energy utilization. Compared to the existing approaches solving only conduction between the ground heat exchanger and the surrou...

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Bibliographic Details
Published in:IOP conference series. Earth and environmental science 2022-08, Vol.1074 (1), p.12007
Main Authors: Ma, Z.D., Jia, G.S., Zhang, Y.P., Miao, C.Y., Xia, Z.H., Jin, L.W.
Format: Article
Language:English
Subjects:
Aquifers
Conduction heating
Convective heat transfer
deep-buried ground heat exchanger
Energy utilization
Field tests
Fluid flow
Geology
Geothermal energy
Geothermal energy utilization
Groundwater
Groundwater flow
Heat exchangers
Heat transfer
Horizontal orientation
Performance evaluation
Performance prediction
Scale models
Three dimensional models
three-dimensional full-scale model
Two dimensional models
Water flow
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Summary:It is critical to precisely determine the performance of deep-buried ground heat exchangers involving different geological layers in engineering projects of the geothermal energy utilization. Compared to the existing approaches solving only conduction between the ground heat exchanger and the surrounding ground based on the two-dimensional model, this paper established a three-dimensional full-scale coaxial ground heat exchanger model containing both aquifer and aquifuge layers involving groundwater effect. The convective heat transfer in pipes was calculated using the empirical correlation of Nusselt number to improve the computation efficiency. The groundwater velocity in the energy governing equation was assumed to be constant and along with the horizontal direction to further simplify the computation. The developed method was applied to a 2800 m and 2600 m depth ground heat exchangers with different geological conditions, and was validated by the field test and published data. The relative errors are less than 6.9%. The thermal influence ranges of the aquifer layer and the aquifuge layer close to aquifer are asymmetric about the circumferential direction. The results demonstrated that the three-dimensional full-scale model is necessary for accurately evaluating the performance of ground heat exchangers when there is groundwater migration.
ISSN:1755-1307
1755-1315
DOI:10.1088/1755-1315/1074/1/012007