Thermal performance of medium-deep U-type borehole heat exchanger based on a novel numerical model considering groundwater seepage

Shuai Huang, Jiqin Li, Hu Gao, Jiankai Dong and Yiqiang Jiang

Renewable Energy, 2024, vol. 222, issue C

Abstract: The medium and deep U-type borehole heat exchanger (MDUBHE) system is a novel technology to extract deep geothermal energy for building heating. The thermal performance of MDUBHE is influenced by multiple factors, where groundwater seepage is one of the most significant factors. To our best knowledge, the effects of groundwater seepage on MDUBHE are still unclear. In this paper, a novel numerical heat transfer model for MDUBHE considering groundwater seepage is proposed, and validated by CFD simulation and experimental data, with root mean square errors of 0.5 °C and 1.8 °C, respectively. Based on the novel numerical model, the effects of groundwater seepage on thermal performance of MDUBHE and thermal recovery characteristics of rock-soil are investigated. The results show that the computational efficiency of the novel numerical model is improved by two orders of magnitude compared with CFD software in the same case. The heat extraction rate of MDUBHE gradually increases with increase of seepage velocity. The heat extraction rate is improved by 13.63 % when the seepage velocity is 5.0 × 10−7 m/s. Furthermore, groundwater seepage can improve the thermal recovery rate of rock-soil. Compared with no groundwater seepage, the thermal recovery rate is improved by 7.60 % when the seepage velocity is 1.0 × 10−7 m/s. This study is significant for revealing the effect of groundwater seepage on the MDUBHE system.

Keywords: Geothermal energy; Numerical heat transfer model; Medium-deep U-Type borehole heat exchanger; Groundwater seepage (search for similar items in EconPapers)
Date: 2024
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Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:222:y:2024:i:c:s0960148124000533

DOI: 10.1016/j.renene.2024.119988

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