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Thermo-hydraulic assessment of energy tunnels under various thermal, hydrogeological and operational conditions

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  • Sheikhahmadi, Seyed Raef
  • Oliaei, Mohammad
  • Akbari Garakani, Amir
  • Kiani Fordoei, Mohammad Amir

Abstract

Energy tunnels, promising structures for shallow geothermal energy extraction, require deeper insights into their thermo-hydraulic behavior. This study investigates the output power from the lining of energy tunnels numerically through a finite element model. After calibrating the model with both numerical and experimental data, the effects of various parameters and groundwater flow (GWF) on output heat were examined. Results demonstrate that pipe diameter and flow velocity dominate output power variation (74 %), exceeding soil thermal properties (8 %). Non-isolated conditions enhance heat exchange compared to isolated setups. GWF significantly boosts output power, with exponential increases up to 436 % at 104-fold velocity rises in isolated, perpendicular flows. GWF amplifies the impact of pipe layout by 0.8 %–10.8 %, and reduces power discrepancies between isolated/non-isolated conditions over time by restoring soil temperatures. Short-term output power surpasses long-term due to soil heat capacity depletion during prolonged operation. Inclined seepage, modeled as multidirectional flow, enhances thermal compensation by 10 %, with two-dimensional flows improving soil temperature recovery beyond one-dimensional flows. This study emphasizes GWF's crucial role in optimizing energy tunnels through GWF velocity and directionality, noting minimal soil influence. It offers quantitative guidelines on pipe configuration and hydrogeological conditions to maximize geothermal system efficiency.

Suggested Citation

  • Sheikhahmadi, Seyed Raef & Oliaei, Mohammad & Akbari Garakani, Amir & Kiani Fordoei, Mohammad Amir, 2025. "Thermo-hydraulic assessment of energy tunnels under various thermal, hydrogeological and operational conditions," Renewable Energy, Elsevier, vol. 247(C).
    • Handle: RePEc:eee:renene:v:247:y:2025:i:c:s0960148125006676
    DOI: 10.1016/j.renene.2025.123005
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    References listed on IDEAS

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    1. Mustafa Omer, Abdeen, 2008. "Ground-source heat pumps systems and applications," Renewable and Sustainable Energy Reviews, Elsevier, vol. 12(2), pages 344-371, February.
    2. Heidari, Bahareh & Yoosefi, Siamak & Garakani, Amir Akbari, 2024. "Assessing the effects of horizontal loads on the ultimate vertical bearing capacity of energy piles: A comparative numerical and analytical study," Renewable Energy, Elsevier, vol. 234(C).
    3. Heidari, Bahareh & Akbari Garakani, Amir & Mokhtari Jozani, Sahar & Hashemi Tari, Pooyan, 2022. "Energy piles under lateral loading: Analytical and numerical investigations," Renewable Energy, Elsevier, vol. 182(C), pages 172-191.
    4. Insana, A. & Barla, M., 2020. "Experimental and numerical investigations on the energy performance of a thermo-active tunnel," Renewable Energy, Elsevier, vol. 152(C), pages 781-792.
    5. Ji, Yongming & Yin, Zhenfeng & Jiao, Jiachen & Ji, Chengfan & Hu, Songtao, 2024. "Long-term operational characteristics of subway source heat pump system under various tunnel internal heat source intensities," Renewable Energy, Elsevier, vol. 236(C).
    6. Yu, Zihao & Zhang, Guozhu & Cui, Hongzhi & Wang, Zhongtao & Cao, Ziming, 2025. "A cross season antifreeze system utilizing tunnel lining GHEs and solar energy: Performance and effect mechanism at various environment parameters," Renewable Energy, Elsevier, vol. 242(C).
    7. Lee, Chulho & Park, Sangwoo & Won, Jongmuk & Jeoung, Jaehyeung & Sohn, Byonghu & Choi, Hangseok, 2012. "Evaluation of thermal performance of energy textile installed in Tunnel," Renewable Energy, Elsevier, vol. 42(C), pages 11-22.
    8. Ogunleye, Oluwaseun & Singh, Rao Martand & Cecinato, Francesco & Chan Choi, Jung, 2020. "Effect of intermittent operation on the thermal efficiency of energy tunnels under varying tunnel air temperature," Renewable Energy, Elsevier, vol. 146(C), pages 2646-2658.
    9. Akbari Garakani, Amir & Mokhtari Jozani, Sahar & Hashemi Tari, Pooyan & Heidari, Bahareh, 2022. "Effects of heat exchange fluid characteristics and pipe configuration on the ultimate bearing capacity of energy piles," Energy, Elsevier, vol. 248(C).
    10. Barbier, Enrico, 2002. "Geothermal energy technology and current status: an overview," Renewable and Sustainable Energy Reviews, Elsevier, vol. 6(1-2), pages 3-65.
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