TY - JOUR
T1 - Applicability evaluation of cast-in-place energy piles based on two-year heating and cooling operation
AU - Park, Sangwoo
AU - Lee, Seokjae
AU - Sung, Chihun
AU - Choi, Hangseok
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Science and ICT, MSIT) (grant number 2019R1A2C2086647).
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/6
Y1 - 2021/6
N2 - An energy pile is a type of ground heat exchanger (GHEX) that can reduce the initial construction cost by being installed in the existing foundation structure (i.e., pile). However, despite economic benefits, energy piles have not been globally employed owing to a lack of construction cases and appropriate design methods. Therefore, in this study, a design method applicable to large-diameter cast-in-place energy piles was developed and verified by conducting long-term monitoring on the heating and cooling operation. In addition, to evaluate the applicability of the cast-in-place energy piles, their thermo-mechanical behaviors and economic feasibility were analyzed using the long-term monitoring results. Although degradation of thermal performance and significant changes in the ground temperature were observed in the heating operation, it was concluded that the proposed design method could provide reliable design outcomes. The maximum thermal stress was estimated to be 2.38 MPa during the long-term monitoring, which is approximately 8.5% of the design strength criterion for cast-in-place concrete. Finally, compared with a conventional closed-loop vertical GHEX, the cast-in-place energy piles could reduce the initial investment cost by 25.31%, and the investment payback period was evaluated to be 1.61 years.
AB - An energy pile is a type of ground heat exchanger (GHEX) that can reduce the initial construction cost by being installed in the existing foundation structure (i.e., pile). However, despite economic benefits, energy piles have not been globally employed owing to a lack of construction cases and appropriate design methods. Therefore, in this study, a design method applicable to large-diameter cast-in-place energy piles was developed and verified by conducting long-term monitoring on the heating and cooling operation. In addition, to evaluate the applicability of the cast-in-place energy piles, their thermo-mechanical behaviors and economic feasibility were analyzed using the long-term monitoring results. Although degradation of thermal performance and significant changes in the ground temperature were observed in the heating operation, it was concluded that the proposed design method could provide reliable design outcomes. The maximum thermal stress was estimated to be 2.38 MPa during the long-term monitoring, which is approximately 8.5% of the design strength criterion for cast-in-place concrete. Finally, compared with a conventional closed-loop vertical GHEX, the cast-in-place energy piles could reduce the initial investment cost by 25.31%, and the investment payback period was evaluated to be 1.61 years.
KW - Cast-in-place energy pile
KW - Ground heat exchanger
KW - Ground source heat pump system
KW - Long-term monitoring
KW - Thermo-mechanical behavior
UR - http://www.scopus.com/inward/record.url?scp=85102271673&partnerID=8YFLogxK
U2 - 10.1016/j.rser.2021.110906
DO - 10.1016/j.rser.2021.110906
M3 - Article
AN - SCOPUS:85102271673
SN - 1364-0321
VL - 143
JO - Renewable and Sustainable Energy Reviews
JF - Renewable and Sustainable Energy Reviews
M1 - 110906
ER -