Material for publication as a Communication must be on a n urgent matter and be of obvious scienti$c importance. Rapidity of publication is enhanced i f diagrams are omitted, but tables and formulae can be included. Communications should not be simple claims for priority: this facility for rapid publication i s intended for brief descriptions of work that has progressed to a stage at which it i s likely to be valuable to workers faced with similar problems. A fuller paper may be ofleered subsequently, if justified by later work.Manuscripts are not subjected to the usual examination by referees and inclusion of a Communication i s at the Editor's discretion.

This paper deals with the feasibility of utilization of the heat carried away with the air stream ventilating a mine after closing down mining operations. The problem is that, although the temperature of air flowing underground is rather high (above 35 o C), the air temperature at the surface level drops to about 25 o C. For that reason it was proposed to cool down the hot air underground and to transport the hot water from cooling machines to the surface level. However, such a solution is not realistic in closed-down mines. So, another idea was considered consisting in exploiting the thermal energy of the exhaust air stream in functioning mines. Further the cooling potential of Polish mines was surveyed. It emerged that for the mines with an active cooling potential in the range of a couple of MW it can be economically viable to transfer the gained thermal energy released due to surface condensation and to use that energy for communal heating. AbstraktČlánek se zabývá možnostmi využití tepla, které je odváděno důlním ovzduším na povrch po ukončení dobývání. I když teplota tohoto ovzduší v dole je poměrně vysoká (více jak 35°C), tak po výstupu na povrch se tato teplota snižuje na cca 25°C. Proto bylo navrženo, aby teplé ovzduší bylo schlazováno v dole a na povrch by se odváděla teplá voda pocházející z chladících zařízení. Toto řešení je ale málo reálné v případě dolu, kde již byla těžba ukončena. Proto další návrh se týká využití tepla obsaženého v použitém důlním ovzduší činných dolů. Byl vyhodnocen chladící potenciál polských kamenouhelných dolů. Z této analýzy vyplývá, že v dolech s činným chladícím potenciálem řádově několika MW, může být ekonomicky výhodný záměr spojený s odváděním kondenzačního tepla, pocházejícího z chladících zařízení, na povrch a jeho využití pro vytápění.

The aim of this study was to examine the effect of the temperature of surrounding rocks on enthalpy and temperature of air flowing along several model mine workings. Long workings surrounded by non--coal rocks as well longwall gates surrounded by coal were taken into consideration. Computer-aided simulation methods were used during the study. At greater depths the amount of moisture transferred into a mine working from the rock mass is two orders of magnitude smaller than the moisture that comes from external (technological) sources, mainly from coal extraction-related processes, therefore in the equation describing temperature changes only the terms representing the flux of heat from rocks were included. The model workings, for calculation purposes, were divided into sections, 50 m in length each. For each of the sections temperature of its ribs and temperature and stream of enthalpy of air flowing along it were calculated with the use of the finite differences method. For workings surrounded by non-coal rocks two variant calculations were carried out, namely with or without technological sources of heat. For coal surrounded workings (longwall gates) a new method for determination of heat from coal oxidation was developed, based on the findings by Cygankiewicz J. (2012aCygankiewicz J. ( , 2012b. Using the results of a study by J.J. Drzewiecki and Smolka (1994), the effects of rock mass fracturing on transfer of heat into the air stream flowing along a working were taken into account. Keywords: safety, ventilation, air-conditioning, heat and mass transferBadano wpływ temperatury pierwotnej skał na strumień entalpii oraz temperaturę powietrza w wyrobisku korytarzowym o długości 2000 m. Rozpatrywano wyrobiska kamienne oraz chodniki podścia-nowe. W badaniach zastosowano metodę symulacji komputerowych. Na dużych głębokościach wilgoć przenoszona z górotworu do wyrobiska jest dwa rzędy wielkości mniejsza od wilgoci pochodzącej od procesów technologicznych. W związku z powyższym w równaniu opisującym zmiany temperatury w masywie skalnym uwzględniono tylko człon reprezentujący ruch ciepła w skałach. Badane wyrobisko podzielono na odcinki o długości 50 m. Korzystając z metody różnic skończonych dla każdego z odcinków wyznaczono temperaturę ociosu, a następnie temperaturę i strumień entalpii powietrza. W odniesieniu do wyrobisk kamiennych rozważania przeprowadzono dla wariantu z technologicznymi źródłami ciepła oraz Cygankiewicza (2012aCygankiewicza ( , 2012b. Korzystając z wyników badań J. Drzewieckiego i J. Smołki (1994), uwzględniono wpływ spękań górotworu na przenoszenie ciepła do powietrza w wyrobisku.Słowa kluczowe: bezpieczeństwo, aerologia, klimatyzacja, przepływ ciepła i masy

Heat flow in a hot mining department, where the original temperature of rock is greater than 50 0 C has been studied. The total power of electrical equipment installed in the department amounts to about 6 MW. In accordance with the current climate regulations of Polish mining, the air temperature in the workplace, measured with a dry-bulb thermometer may not be higher than 33 0 C. In order to be able to ensure a temperature consistent with the regulations in such department, fresh air supply workings must be equipped with chillers of a total refrigeration capacity of 2 MW. The carried out analysis of the results of climate forecasts and of the results of the rock mass cooling modelling around these workings has shown that approximately 30% of the cooling power is needed to receive the heat from the hot rock massif. Assuming the required air temperature at 28 0 C (enabling an unshortened working time), then the cooling power needed to extract heat from the rock mass would be much greater. The studies carried out show that the amount of heat emitted in the department also depends on the phase of the longwall course (the length of main gates and changes in rock temperature in them). It has been proposed that hot water from condensers supplies the crystallizers of surface (absorption) cooling devices. In this way, reduction of the air-conditioning expenditure will be obtained.

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