IDEAS home Printed from https://ideas.repec.org/a/gam/jeners/v18y2025i9p2361-d1649762.html
   My bibliography  Save this article

Heat Transfer Enhancement in Coaxial Downhole Heat Exchangers: Influence of Spiral Fins at the Bottom Section

Author

Listed:
  • Xinliu Yang

    (State Key Laboratory of Deep Geothermal Resources, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China)

  • Qiang Liu

    (State Key Laboratory of Deep Geothermal Resources, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China)

  • Gui Lu

    (School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China)

Abstract

Coaxial downhole heat exchangers (CDHEs) extract heat directly from geothermal reservoirs through a closed loop, minimizing environmental impacts. However, the heat extraction efficiency is generally lower than that of groundwater harvesting technology. This study proposes integrating spiral fins on the CDHE outer tube’s inner surface to enhance heat transfer performance. Numerical simulations demonstrate that placing spiral fins on the inner wall of the outer tube significantly enhances rotational velocity and turbulence within the annular flow channel, outperforming configurations with fins on the outer wall of the inner tube. The intensified swirling flow extends to the bottom of the CDHE, promoting effective mixing of hot and cold fluids and consequently improving the heat transfer coefficient. This study also investigates the influence of fin pitch and height on heat transfer and flow characteristics. The results show that both the Nusselt number ( Nu ) and flow resistance increase as fin pitch decreases, causing the performance evaluation criteria ( PEC ) to initially increase and then decrease. Additionally, increased fin height enhances the heat transfer coefficient, but also leads to a greater pressure drop. The optimal performance was achieved with a fin pitch of 500 mm and a fin height of 10 mm, attaining a maximum PEC of 1.53, effectively balancing heat transfer enhancement and hydraulic resistance. These findings provide guidance for the structural optimization of coaxial downhole heat exchangers.

Suggested Citation

  • Xinliu Yang & Qiang Liu & Gui Lu, 2025. "Heat Transfer Enhancement in Coaxial Downhole Heat Exchangers: Influence of Spiral Fins at the Bottom Section," Energies, MDPI, vol. 18(9), pages 1-21, May.
  • Handle: RePEc:gam:jeners:v:18:y:2025:i:9:p:2361-:d:1649762
    as

    Download full text from publisher

    File URL: https://www.mdpi.com/1996-1073/18/9/2361/pdf
    Download Restriction: no

    File URL: https://www.mdpi.com/1996-1073/18/9/2361/
    Download Restriction: no
    ---><---

    References listed on IDEAS

    as
    1. Meng, Dongyu & Liu, Qiang & Ji, Zhongli, 2022. "Effects of two-phase expander on the thermoeconomics of organic double-flash cycles for geothermal power generation," Energy, Elsevier, vol. 239(PD).
    2. Alimonti, C. & Soldo, E., 2016. "Study of geothermal power generation from a very deep oil well with a wellbore heat exchanger," Renewable Energy, Elsevier, vol. 86(C), pages 292-301.
    3. Muhammad Asad & Vincenzo Guida & Alessandro Mauro, 2023. "Experimental and Numerical Analysis of the Efficacy of a Real Downhole Heat Exchanger," Energies, MDPI, vol. 16(19), pages 1-19, September.
    4. Hao Yu & Xinli Lu & Wei Zhang & Jiali Liu, 2024. "Thermodynamic Analysis of an Increasing-Pressure Endothermic Power Cycle Integrated with Closed-Loop Geothermal Energy Extraction," Energies, MDPI, vol. 17(7), pages 1-23, April.
    5. Kuan Li & Bing Li & Shanshan Shi & Zhenyu Wu & Hengchun Zhang, 2025. "Research and Application of Drilling Fluid Cooling System for Dry Hot Rock," Energies, MDPI, vol. 18(7), pages 1-15, March.
    6. Jello, Josiane & Baser, Tugce, 2023. "Utilization of existing hydrocarbon wells for geothermal system development: A review," Applied Energy, Elsevier, vol. 348(C).
    7. Oh, Kwanggeun & Lee, Seokjae & Park, Sangwoo & Han, Shin-In & Choi, Hangseok, 2019. "Field experiment on heat exchange performance of various coaxial-type ground heat exchangers considering construction conditions," Renewable Energy, Elsevier, vol. 144(C), pages 84-96.
    8. Zheng, Jianqiao & Zhang, Yanjun & Huang, Yibin & Liu, Qiangbin & Cheng, Yuxiang & Guo, Jixiang, 2024. "Numerical investigation on heat transfer performance of the segmented cementing coaxial heat exchanger," Renewable Energy, Elsevier, vol. 220(C).
    9. Quirosa, Gonzalo & Torres, Miguel & Becerra, José A. & Jiménez-Espadafor, Francisco J. & Chacartegui, Ricardo, 2023. "Energy analysis of an ultra-low temperature district heating and cooling system with coaxial borehole heat exchangers," Energy, Elsevier, vol. 278(PA).
    10. Gao, Xiang & Wang, Zeyu & Qiao, Yuwen & Li, Tailu & Zhang, Yao, 2024. "Effects of seepage flow patterns with different wellbore layout on the heat transfer and power generation performance of enhanced geothermal system," Renewable Energy, Elsevier, vol. 223(C).
    11. Chen, Hongfei & Liu, Hongtao & Yang, Fuxin & Tan, Houzhang & Wang, Bangju, 2023. "Field measurements and numerical investigation on heat transfer characteristics and long-term performance of deep borehole heat exchangers," Renewable Energy, Elsevier, vol. 205(C), pages 1125-1136.
    12. Dai, Chuanshan & Li, Jiashu & Shi, Yu & Zeng, Long & Lei, Haiyan, 2019. "An experiment on heat extraction from a deep geothermal well using a downhole coaxial open loop design," Applied Energy, Elsevier, vol. 252(C), pages 1-1.
    Full references (including those not matched with items on IDEAS)

    Most related items

    These are the items that most often cite the same works as this one and are cited by the same works as this one.
    1. Luka Boban & Dino Miše & Stjepan Herceg & Vladimir Soldo, 2021. "Application and Design Aspects of Ground Heat Exchangers," Energies, MDPI, vol. 14(8), pages 1-31, April.
    2. Pokhrel, Sajjan & Sasmito, Agus P. & Sainoki, Atsushi & Tosha, Toshiyuki & Tanaka, Tatsuya & Nagai, Chiaki & Ghoreishi-Madiseh, Seyed Ali, 2022. "Field-scale experimental and numerical analysis of a downhole coaxial heat exchanger for geothermal energy production," Renewable Energy, Elsevier, vol. 182(C), pages 521-535.
    3. Zolfagharroshan, Mohammad & Xu, Minghan & Boutot, Jade & Zueter, Ahmad F. & Tareen, Muhammad S.K. & Kang, Mary & Sasmito, Agus P., 2024. "Assessment of geothermal energy potential from abandoned oil and gas wells in Alberta, Canada," Applied Energy, Elsevier, vol. 375(C).
    4. Zhen Zhao & Guangxiong Qin & Huijuan Chen & Linchao Yang & Songhe Geng & Ronghua Wen & Liang Zhang, 2022. "Numerical Simulation and Economic Evaluation of Wellbore Self-Circulation for Heat Extraction Using Cluster Horizontal Wells," Energies, MDPI, vol. 15(9), pages 1-26, April.
    5. Theo Renaud & Patrick G. Verdin & Gioia Falcone, 2020. "Conjugated Numerical Approach for Modelling DBHE in High Geothermal Gradient Environments," Energies, MDPI, vol. 13(22), pages 1-18, November.
    6. Behzadi, Amirmohammad & Duwig, Christophe & Ploskic, Adnan & Holmberg, Sture & Sadrizadeh, Sasan, 2024. "Application to novel smart techniques for decarbonization of commercial building heating and cooling through optimal energy management," Applied Energy, Elsevier, vol. 376(PA).
    7. Deng, Jiewen & Su, Yangyang & Peng, Chenwei & Qiang, Wenbo & Cai, Wanlong & Wei, Qingpeng & Zhang, Hui, 2023. "How to improve the energy performance of mid-deep geothermal heat pump systems: Optimization of heat pump, system configuration and control strategy," Energy, Elsevier, vol. 285(C).
    8. C, Alimonti & P, Conti & E, Soldo, 2019. "A comprehensive exergy evaluation of a deep borehole heat exchanger coupled with a ORC plant: the case study of Campi Flegrei," Energy, Elsevier, vol. 189(C).
    9. Dong, Shihao & Yu, Yuelong & Li, Bingxue & Ni, Long, 2024. "Geologic and thermal conductivity analysis based on geophysical test and combined modeling," Energy, Elsevier, vol. 310(C).
    10. Yujiang He & Xianbiao Bu, 2020. "Performance of Hybrid Single Well Enhanced Geothermal System and Solar Energy for Buildings Heating," Energies, MDPI, vol. 13(10), pages 1-10, May.
    11. Alimonti, C. & Soldo, E. & Bocchetti, D. & Berardi, D., 2018. "The wellbore heat exchangers: A technical review," Renewable Energy, Elsevier, vol. 123(C), pages 353-381.
    12. Mahmoud, Montaser & Alkhedher, Mohammad & Ramadan, Mohamad & Naher, Sumsun & Pullen, Keith, 2022. "An investigation on organic Rankine cycle incorporating a ground-cooled condenser: Working fluid selection and regeneration," Energy, Elsevier, vol. 249(C).
    13. Zuo, Yinhui & Sun, Yigao & Zhang, Luquan & Zhang, Chao & Wang, Yingchun & Jiang, Guangzheng & Wang, Xiaoguang & Zhang, Tao & Cui, Longqing, 2024. "Geothermal resource evaluation in the Sichuan Basin and suggestions for the development and utilization of abandoned oil and gas wells," Renewable Energy, Elsevier, vol. 225(C).
    14. Xia, Z.H. & Jia, G.S. & Ma, Z.D. & Wang, J.W. & Zhang, Y.P. & Jin, L.W., 2021. "Analysis of economy, thermal efficiency and environmental impact of geothermal heating system based on life cycle assessments," Applied Energy, Elsevier, vol. 303(C).
    15. Huang, Wenbo & Cao, Wenjiong & Jiang, Fangming, 2018. "A novel single-well geothermal system for hot dry rock geothermal energy exploitation," Energy, Elsevier, vol. 162(C), pages 630-644.
    16. Luo, Yongqiang & Shen, Junhao & Song, Yixiao & Liu, Qingyuan & Huo, Fulei & Chu, Zhanpeng & Tian, Zhiyong & Fan, Jianhua & Zhang, Ling & Liu, Aihua, 2024. "Multi-segmented tube design and multi-objective optimization of deep coaxial borehole heat exchanger," Renewable Energy, Elsevier, vol. 237(PA).
    17. Jia, G.S. & Ma, Z.D. & Xia, Z.H. & Zhang, Y.P. & Xue, Y.Z. & Chai, J.C. & Jin, L.W., 2022. "A finite-volume method for full-scale simulations of coaxial borehole heat exchangers with different structural parameters, geological and operating conditions," Renewable Energy, Elsevier, vol. 182(C), pages 296-313.
    18. Gharibi, Shabnam & Mortezazadeh, Emad & Hashemi Aghcheh Bodi, Seyed Jalaledin & Vatani, Ali, 2018. "Feasibility study of geothermal heat extraction from abandoned oil wells using a U-tube heat exchanger," Energy, Elsevier, vol. 153(C), pages 554-567.
    19. Yao, Shuai & Wu, Jianzhong & Qadrdan, Meysam, 2024. "A state-of-the-art analysis and perspectives on the 4th/5th generation district heating and cooling systems," Renewable and Sustainable Energy Reviews, Elsevier, vol. 202(C).
    20. Jianlin Li & Xupeng Qi & Xiaoli Li & Huijie Huang & Jian Gao, 2025. "Research on the Optimized Design of Medium and Deep Ground-Source Heat Pump Systems Considering End-Load Variation," Sustainability, MDPI, vol. 17(7), pages 1-24, April.

    More about this item

    Keywords

    ;
    ;
    ;
    ;
    ;

    Statistics

    Access and download statistics

    Corrections

    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:gam:jeners:v:18:y:2025:i:9:p:2361-:d:1649762. See general information about how to correct material in RePEc.

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    If CitEc recognized a bibliographic reference but did not link an item in RePEc to it, you can help with this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: MDPI Indexing Manager (email available below). General contact details of provider: https://www.mdpi.com .

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service. RePEc uses bibliographic data supplied by the respective publishers.