| Abstract |
Heat-flow density in Poland varies from 20 to 90 mW/mí, as indicated by temperature surveys in several dozen deep wells. Temperatures at loo0 m depth vary from 35 to over 50íC. The geothermal beat is relatively easily available in deep mine workings, where terrestrial heat flow exceeds SO mW/mí; initial depth-dependent temperatures reach 15 to 45?C. Numerical modelling of heat transfer by conduction and convection has been used to simulate the beat flux from surrounding rocks into water in a geothermal reservoir created in mines at up to loo0 m depth with a capacity of several million cubic meters. It is shown that heat flux induced due to the water rock temperature difference in nune openings is much higher of the order of W/m2 rather than the mW/mí of terrestrial heat flow. Damp backfillings may be also utilized as heat collectors, loaded with heat recovered at the surface in summer from both space and parking pavement cooling systems. Productive coal mines in the Silesian region of southwest Poland are cooled down by gravitational water inflow and, artificially, by ventilation air. Considerable contributions to the rise of temperature in mines come from the oxidation processes of sulfides and coal matter, the exhaust beat of electric engines and even the body heat of hard-working miners. In abandoned, dormant mines, the ventilation system ceases, water becomes stagnant and the temperature rises. Mine beat energy can be extracted from rocks, pumped-up waters (especially those from deep wells made for methane extraction), ventdation air and backfilling in abandoned underground spaces. |