Study on heat-exchange efficiency and energy efficiency ratio of a deeply buried pipe energy pile group considering seepage and circulating-medium flow rate

Zhi Chen, Xingwei Lian, Jinjia Tan, Henglin Xiao, Qiang Ma and Yan Zhuang

Renewable Energy, 2023, vol. 216, issue C

Abstract: Seepage and circulating-medium flow rate are both primary factors affecting the heat-exchange efficiency and energy efficiency ratio of underground energy structures. In this study, a thermal-seepage coupled model of a deeply buried pipe energy pile group is developed, and the effects of circulating-medium flow rate, seepage velocity, and thermal migration caused by seepage on heat-exchange efficiency and energy efficiency ratio are analyzed. The results show that increasing the circulating-medium flow rate can improve heat-exchange efficiency, but aggravate heat accumulation, resulting in energy efficiency ratio reduction. Seepage can eliminate the heat accumulation as well as improve the heat-exchange efficiency and energy efficiency ratio. The heat accumulated around upstream piles will migrate along the seepage direction, generating thermal disturbance to the downstream piles. An increase in the circulating-medium flow rate of upstream deeply buried pipe energy piles will aggravate thermal disturbance. This phenomenon is slightly retarded if seepage velocity is increased. Additionally, when the circulating-medium flow rate of the deeply buried pipe energy pile group under seepage is within the optimal range, slightly reducing the circulating-medium flow rate of the upstream deeply buried pipe energy piles can reduce thermal disturbance to the downstream piles without affecting the overall heat-exchange efficiency.

Keywords: Deeply buried pipe energy pile group; Heat accumulation; Circulating-medium flow rate; Seepage velocity; Thermal migration (search for similar items in EconPapers)
Date: 2023
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Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:216:y:2023:i:c:s0960148123009345

DOI: 10.1016/j.renene.2023.119020

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