Long-Term efficiency of horizontal closed-loop geothermal systems for seasonal freeze-back stabilization of permafrost
Wastewater treatment lagoons are practical and cost-effective systems 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. A wastewater treatment lagoon system was designed and monitored by KGS Group in northern Yukon.
This research aims to evaluate the long-term efficiency of the horizontal closed-loop geothermal freeze-back concept proposed by KGS Group. For this purpose, a 3D finite element simulation will be developed to simulate different involved physics including 1) the porous media and its physical characteristics such as dimensions and porosity; 2) heat transfer problem in porous media; 3) pore water phase change to model thawing permafrost and seasonal freezing and thawing at the ground surface; 4) fluid flow through the porous media; and 5) pipe flow and heat exchange through its walls.