LAPSE:2023.27091
Published Article
LAPSE:2023.27091
Field Test and Numerical Simulation on Heat Transfer Performance of Coaxial Borehole Heat Exchanger
April 3, 2023
Abstract
Ground thermal properties are the design basis of ground source heat pumps (GSHP). However, effective ground thermal properties cannot be obtained through the traditional thermal response test (TRT) method when it is used in the coaxial borehole heat exchanger (CBHE). In this paper, an improved TRT (ITRT) method for CBHE is proposed, and the field ITRT, based on the actual project, is carried out. The high accuracy of the new method is verified by laboratory experiments. Based on the results of the ITRT and laboratory experiment, the 3D numerical model for CBHE is established, in which the flow directions, sensitivity analysis of heat transfer characteristics, and optimization of circulation flow rate are studied, respectively. The results show that CBHE should adopt the anulus-in direction under the cooling condition, and the center-in direction under the heating condition. The influence of inlet temperature and flow rate on heat transfer rate is more significant than that of the backfill grout material, thermal conductivity of the inner pipe, and borehole depth. The circulating flow rate of CBHE between 0.3 m/s and 0.4 m/s can lead to better performance for the system.
Ground thermal properties are the design basis of ground source heat pumps (GSHP). However, effective ground thermal properties cannot be obtained through the traditional thermal response test (TRT) method when it is used in the coaxial borehole heat exchanger (CBHE). In this paper, an improved TRT (ITRT) method for CBHE is proposed, and the field ITRT, based on the actual project, is carried out. The high accuracy of the new method is verified by laboratory experiments. Based on the results of the ITRT and laboratory experiment, the 3D numerical model for CBHE is established, in which the flow directions, sensitivity analysis of heat transfer characteristics, and optimization of circulation flow rate are studied, respectively. The results show that CBHE should adopt the anulus-in direction under the cooling condition, and the center-in direction under the heating condition. The influence of inlet temperature and flow rate on heat transfer rate is more significant than that of the backfill grout material, thermal conductivity of the inner pipe, and borehole depth. The circulating flow rate of CBHE between 0.3 m/s and 0.4 m/s can lead to better performance for the system.
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Keywords
coaxial borehole heat exchangers, ground source heat pumps, improved thermal response test, sensitivity analysis
Subject
Suggested Citation
Li P, Guan P, Zheng J, Dou B, Tian H, Duan X, Liu H. Field Test and Numerical Simulation on Heat Transfer Performance of Coaxial Borehole Heat Exchanger. (2023). LAPSE:2023.27091
Author Affiliations
Li P: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Guan P: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Zheng J: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Dou B: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Tian H: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China [ORCID]
Duan X: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Liu H: Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
Guan P: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Zheng J: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Dou B: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Tian H: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China [ORCID]
Duan X: Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; National Center for International Research on Deep Earth Drilling and Resource Development, Wuhan 430074, China
Liu H: Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
Journal Name
Energies
Volume
13
Issue
20
Article Number
E5471
Year
2020
Publication Date
2020-10-19
ISSN
1996-1073
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PII: en13205471, Publication Type: Journal Article
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LAPSE:2023.27091
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https://doi.org/10.3390/en13205471
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