2025-05-28 スイス連邦工科大学ローザンヌ校(EPFL)
＜関連情報＞
- https://actu.epfl.ch/news/epfl-engineers-explore-new-applications-for-geothe/
- https://www.sciencedirect.com/science/article/pii/S0886779825003359?via%3Dihub
気流条件を考慮した地下鉄駅の地熱ポテンシャル評価 Evaluating the geothermal potential of a metro station considering its airflow conditions
Sofie ten Bosch, Elena Ravera, Marco Tobler, Marco Bettelini, Lyesse Laloui
Tunnelling and Underground Space Technology Available online: 3 May 2025
DOI:https://doi.org/10.1016/j.tust.2025.106697
Highlights
- This work presents numerical simulations of a geothermally activated metro station.
- Computational fluid dynamics is used to evaluate air domain considerations.
- Geothermal potential is assessed for a variety of realistic airflow scenarios.
- Average heat transfer coefficient use is validated for time-varying boundary conditions.
- Interaction effects between geothermally activated sections are identified.
Abstract
This study examines the influence of the internal air environment on the geothermal potential of a metro station in Bucharest with a standard design commonly found in metro stations. It addresses the challenges posed by factors such as train movement on air circulation and braking, passenger flow, and technical infrastructure on temperature patterns within the station respectively. The aim is to evaluate the feasibility of utilizing energy geostructures within the station considering the influence of waste heat, with the objective of improving cooling and ventilation systems and reducing the impact on the surrounding underground climate change. This aspect is evaluated using three-dimensional numerical modelling. A novel modelling approach is used to account for the air domains in the metro station due to its complex geometry. Convective heat transfer boundary conditions are implemented based on computational fluid dynamics simulations of the full air domain, accounting for the variation in airflow conditions caused by the passing of metro trains. This allows assessing the variation in geothermal potential caused by variations in airflow conditions, soil temperatures and representative air temperatures inside the station, which is a core aspect of the design of energy geostructures. The work demonstrates the possibility of working with an equivalent wall heat transfer coefficient to represent the variation in airflow conditions over time caused by the passing of metros. Furthermore, the influence of interaction effects between different geothermally activated sections is evaluated. This is an essential aspect to consider during the design phase for the determination of geothermal potential. Through these factors, the study contributes to improving the understanding of the physical mechanisms relevant for geothermal activation of metro stations and presents a novel approach to account for the airflow conditions in these underground infrastructures in the assessment of geothermal potential.
地下データセンターにおける換気システムと地中熱システムの相互作用の評価と利用 Assessing and exploiting the interaction between ventilation and geothermal systems in an underground data centre
Sofie ten Bosch, Elena Ravera, Marco Tobler, Marco Bettelini, Lyesse Laloui
Tunnelling and Underground Space Technology Available online: 23 December 2023
DOI:https://doi.org/10.1016/j.tust.2023.105563
Highlights
- This work presents numerical simulations of an energy underground data centre.
- The interaction between ventilation and geothermal systems is explored.
- Geothermal activation can reduce the air temperature in an underground data centre.
- A design optimization framework based on Nusselt correlations is presented.
- Both economic and environmental considerations show the impact of the development.
Abstract
Digitalization and population growth lead to the development of underground data centres, while simultaneously current climate goals stimulate the development of renewable energy sources. In this framework, this study evaluates the so far unexplored domain of geothermal activation of an underground data centre using numerical modelling. Computational fluid dynamics simulations are used to properly represent the air domain. The focus of the work lies on the analysis of the interaction between ventilation and geothermal systems in the data centre, a topic that has never been evaluated for energy geostructures in general. This leads to the possibility of suboptimal air ventilation system design and thus a potential for optimization, especially in underground data centres where daily ventilation requirements are determined by air temperature limitations. The analysis first explores the sensitivity of geothermal potential to varying ventilation conditions (airflow velocities), heat release conditions in the data centre and fluid velocities in the pipes of the geothermal activation. The impact of geothermal activation on air temperature in the underground data centre cavern is then assessed and thus the consequent impact on the ventilation system. Geothermal activation of a section of the cavern leads to a regional decrease in air temperature, which allows optimization of the whole system by reducing mechanical ventilation requirements while still respecting the temperature limitations within the data centre. The economic and environmental benefits of this optimization are also explored. Overall, it is proven that ventilation conditions have an influence on the geothermal potential that can be extracted, and optimization of the complete system is possible when considering the effect of geothermal heat extraction in underground data centres while determining their ventilation requirements.
