Arctic Foundations of Canada manufactures permafrost foundation systems incorporating thermosyphons under the trade names Thermo Piles and Thermo Probes. Our passively refrigerated foundation systems for use in permafrost soils are the original and most widely used in Canada and Alaska. These foundations are economical, energy free, low maintenance and long lasting.
Thermo Piles and Thermo Probes passively remove heat from the foundation soils to:
Create permafrost or prevent it from thawing
Increase the strength of frozen or thawed soils
Eliminate frost heaving
Collectively the three principals have over 90 years of experience in construction and engineering in the arctic, ranging from Alaska in the west to Baffin Island in the east and Alert in the north. All three are actively involved in the hands-on process of design, estimating, manufacturing and field work, providing continuity throughout the project. Arctic Foundations prides itself on providing quality products and workmanship, and backs this up with guarantees.
Products, Technologies & Applications
2 Phase Thermosyphons
Two-phase thermosyphons are passive refrigeration devices that transfer heat against gravity. Construction is typically a closed-ended tubular vessel charged with a two-phase working fluid.
Thermopiles are thermosyphons that carry a structural load. The energy-free refrigeration ability maintains lower soil temperatures, resulting in increased adfreeze, shear and compressive strength of the frozen soil.
Thermoprobes are non-structural, high-capacity two-phase thermosyphons that are used to provide passive refrigeration to maintain or create permafrost.
Applications for AFC technology are many and varied. The original and still most prevalent application is permafrost stabilization. Other applications are containment and barriers for hazardous waste, and mining and dams.
This technology has been in use since the 1960s and has been utilized on over 900 installations. Most of these applications have been in arctic climates where soil freezing is accomplished passively (i.e. without the use of power). The essence of thermosyphon technology is well developed irrespective of the climate it is applied in.
The cooling can be concentrated at predetermined subgrade depths through selective control of the wetted surface. Conventional liquid systems cannot selectively concentrate the cooling to a subgrade location because they experience their maximum temperature differentials near the refrigeration unit above ground.
Two-phase systems are inherently more efficient than single-phase systems. The heat transfer associated with the liquid-to-gas and gas-to-liquid phase change is thermodynamically more efficient than the heat transfer attributes of single-phase liquids or gases.
Mining & Dams
Ground freezing can be a beneficial technology for dam building without regard to any specific industry or the purpose the dam serves. Containing waste is only one of many aqueous liquids that are controlled by dams — clean water being the most common, whether for storage or flow control.
Dams are typically constructed with an impervious core such as clay, but a frozen core can be used just as effectively, although it is not a well-known method in temperate regions. Sometimes the purpose of a dam is water storage, and sometimes it is to keep water from invading a downstream area where activities such as mining are being conducted. If you visualize a large mining excavation next to a lake, you can understand the potential for the lake water to invade the adjacent lower area. A dam would mitigate this potential. A frozen dam can be even more effective than a traditional type because freezing can more effectively seal multiple soil types in the dam, and if necessary, well below it.
Permafrost
Permafrost is any soil or rock maintained at or below 0 °C for a minimum of two years. As long as more heat is removed than is added, a permafrost mass will be maintained. AFI’s two-phase thermosyphons operate when the condenser is colder than the liquid in the evaporator, or when the air is colder than the ground.
Thermal design of a foundation to maintain permafrost must extract the heat from the building or seasonal thaw from above, geothermal heat from below, heat from warmer soils surrounding the site, buried water and sewer lines, runoff from building roofs, and surface drainage. The design must also allow for seasonal thaw without affecting the foundation.
