Numerical study on the performance of combined air- and water-cooling system for large deep underground space

The exploitation of deep sub-surface energy and resources and maintenance of large-scale underground infrastructures require effective cooling systems to ensure stable and agreeable temperature. Here we introduce an innovative cooling system combining surface air and water pipes to regulate undergro...

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Bibliographic Details
Main Authors: Jiaqi Zhang, Lizhi Zhao, Yingchun Li, Chun’an Tang, Zhengzhao Liang, Jun Wang
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Energy Conversion and Management: X
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Online Access:http://www.sciencedirect.com/science/article/pii/S2590174525003265
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Summary:The exploitation of deep sub-surface energy and resources and maintenance of large-scale underground infrastructures require effective cooling systems to ensure stable and agreeable temperature. Here we introduce an innovative cooling system combining surface air and water pipes to regulate underground temperatures from 100 °C to 300 °C. The system characterizes an insulation layer formed by pipes buried in surrounding walls to accommodate water flow, which minimizes heat transfer to walls, reduces air-cooling energy consumption and recycles geothermal energy. Numerical simulations of system operation revealed that for the formation temperatures of 100, 200 and 300°C, this system can ensure that 95 % of the wall temperature drops below 30 °C, and form a 2  m-thick low-temperature zone below 40 °C near the wall surface. Thanks to the low-temperature layer, after nine months running, lowering air velocity to 0.6  m/s reduces air energy consumption by 40 % and maintains 98 % of wall temperatures under 30 °C. This system can also recover over 55 % of the geothermal energy for use in heating and other purposes. Our findings guide achieving sustained workable conditions for engineered underground systems where large space cooling is required.
ISSN:2590-1745