Assessment of a Closed-Loop Geothermal System for Seasonal Freeze-Back Stabilization of Permafrost
Maryam Saaly, Rob Sinclair, David Kurz, Pooneh Maghoul, Hartmut Hollander, Amir Fatollahzadeh Gheisari
In the proceedings of: GeoVirtual 2020: 73rd Canadian Geotechnical ConferenceABSTRACT: Wastewater treatment lagoons are practical and cost-effective system for smaller towns across Canada to prevent wastewater seepage into the environment. Essentially all structures over permafrost that disrupt the natural winter temperatures contacting the ground surface initiates permafrost thawing over the long-term and this includes lagoons. KGS Group has been developing the concept of using conventional closed-loop geothermal systems within the sediments below the base of lagoon to allow a refrigerated solution to be circulated to freeze the soil below the lagoon. This paper assesses the effectiveness of the geothermal freeze-back concept using a heat transfer model developed in COMSOL Multiphysics. The model evaluates variable flow velocities of 0.5 m/s and 0.25 m/s with the circulation of the antifreeze solution to temperatures as low as -20°C. The results of this assessment will provide valuable understanding of the design and costs of a conventional geothermal freeze-back system for large developments over permafrost.
RÉSUMÉ: Les étangs d'épuration représentent un système pratique et rentable de prévention des fuites des eaux usées dans l'environnement pour les petites villes canadiennes. Toutes les structures (incluant les étangs d'épuration) présentes sur le pergélisol et qui perturbent les températures hivernales naturelles sur la surface du sol stimulent le dégel du pergélisol à long terme. Le groupe KGS développe le concept conventionnel qui consiste à réutiliser les installations géothermiques à circuit fermé, et qui circulent dans les sédiments sous la base des étangs d'épuration, pour permettre à la solution réfrigérante de refroidir la sol sous les installations. Cet article évalue l'efficacité du concept de recongélation en utilisant un modèle de transfert de chaleur développé à l'aide de COMSOL Multiphysics. Le modèle évalue ainsi des vitesses d'écoulement variant entre 0.5 m/s à 0.25 m/s en considérant la circulation d'une solution antigel à des températures aussi basses que -20°C. Les résultats de cette évaluation fourniront une compréhension inestimable du design ainsi que des coûts d'un système conventionnel de recongélation géothermique pour les aménagements larges sur le pergélisol.
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Saaly, Maryam, Sinclair, Rob, Kurz, David, Maghoul, Pooneh, Hollander, Hartmut, Gheisari, Amir Fatollahzadeh (2020) Assessment of a Closed-Loop Geothermal System for Seasonal Freeze-Back Stabilization of Permafrost in GEO2020. Ottawa, Ontario: Canadian Geotechnical Society.
@article{Saaly_GEO2020_343,
author = {Saaly, Maryam}, {Sinclair, Rob}, {Kurz, David}, {Maghoul, Pooneh}, {Hollander, Hartmut}, {Gheisari, Amir Fatollahzadeh},
title = Assessment of a Closed-Loop Geothermal System for Seasonal Freeze-Back Stabilization of Permafrost ,
year = 2020
}
title = Assessment of a Closed-Loop Geothermal System for Seasonal Freeze-Back Stabilization of Permafrost ,
year = 2020
}