METHOD OF EXTRACTION AND USE OF GEOTHERMAL HEAT FOR COOLING SOILS AROUND SUBWAY TUNNELS

摘要

FIELD: technological processes.;SUBSTANCE: invention relates to methods of using the extracted geothermal heat to cool the soil around the subway tunnels and transform it to heat water in a hot water system. Geothermal heat is extracted from the soils surrounding the subway tunnels with a ground-based low-temperature heat exchanger buried in the ground, which is a set of plug-in circuits made of 32–40 mm diameter polyethylene pipes without butt joints. Contours are laid flat spiral-helical coils at a depth of 2–4 m from the earth's surface below the depth of freezing over the arches of the underground tunnels with a pitch of 0.7–0.8 m, the diameter of the coils is 800–1,000 mm. Number of contours is determined by calculation. Length of the connected circuits made the same 100–120 m. Heat recovered is accumulated in the coolant, which is an ice-free thirty-percent propylene glycol aqueous solution pumped into the pipe under a pressure of 4 atm, circulating at a speed of at least 0.3 m/s over a closed external circuit. Coolant enters the collecting manifolds, from where it is pumped to the heat pump, which transfers heat from the coolant to the water flowing through the pipe from the water supply system and heats it for use by consumers in the hot water system.;EFFECT: lowering the temperature of the ground around the underground tunnels, increasing heat transfer through the tunnel walls, using the extracted heat for the needs of hot water supply systems.;1 cl, 2 dwg