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1
Content available remote Experimental determination thermal conductivity of dolomitic limestone
Nemec P., Malcho M.
Journal of New Technologies in Environmental Science
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2018
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Vol. 2, nr 1
3--7
EN
The origin of geothermal energy is in the hot core of the Earth. Due its inexhaustible potential, it is also included among renewable sources. Renewable sources are, from the point of view of national economies, domestic resources that have the potential to replace and in the future, in certain applications, completely dispose of fossil fuels. These sources already offer the opportunity to significantly diversify energy sources in each country. Their development is also seen as an important tool to protect the national economy from future shocks from the rise in imported fuel prices and the cost of environmental damage [1]. Heat from the Earth's rock is obtained from deep boreholes of 100 m to 300 m. Systems for acquiring natural thermal energy from the ground are referred to as ground (wells) - water, i.e. that the rocks are the source of thermal energy that is pumped from the rocks through a circulating antifreeze mixture into a hermetically sealed collector. The heat pump produces a heat output of up to 65°C through the compressor, which is sufficient for the hot water heating system or for hot water heating [2]. Limestone and dolomite make up four fifths of all sediments on the Earth's surface. The transition between dolomite and limestone is not sharp, and thus is form a dolomitic limestone - a rock made of dolomite and a predominant limestone. Dolomite is a rock of sedimentary origin. It consists predominantly of a mineral of the same name. It is formed by settling of CaMg(CO3) in hypersalinic aqueous medium, but more often it results from dolomitization of settled limestones [3]. In Slovakia and especially in the Žilina region there is a large number of sites on dolomitic limestone, so it is necessary to know the properties of these rocks in what composition they occur in nature. The course of the temperature field in the rock mass can be determined by direct field measurements and analytical calculations. Mostly on-site measurement results provide input data for analytical calculation. On the other hand, the analytical calculation applies to the ideal body, and the information thus obtained provides a sort of temperature field course. By comparison, we can determine whether the temperature field in a rock mass based on the calculations is real or is loaded by errors (in measurements, in ignorance of structural - texture parameters, moisture and other aspects of material and mass) [4].
2
Influence of temperature during manufacture of the heat pipe filled with fluid FC-72 on its function
Nemec P., Kaduchová K., Jelušová S., Ochodek T., Koloničný J.
Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne
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2014
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Z. 18
150--156
EN
Heat pipes transfer heat at a minimum temperature difference between evaporating and condensing phase. Operating temperature of heat pipe is determined by working fluid and vacuum achieved during production. This paper is focused on determining the effect of initial temperature of ambient air to the performance characteristics of produced heat pipes. In general, a decrease in pressure decreases the boiling liquid. Based on this it can be presumed that achieving a lower temperature during production of heat pipe, the lower vacuum, while the boiling point working fluid while increasing ability to heat transport.
3
Content available Measuring thermal performance of gravitational heat pipes depending on the amount of working fluid
Jobb M., Nemec P., Kosa L., Malcho M.
Structure and Environment
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2014
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Vol. 6, no. 1
43--45
EN
This paper deals with an impact of working medium on the performance parameters of the heat pipe. The aim was to find the ideal amount of working fluid used in gravitational heat pipes. For the working medium 96% alcohol was selected.
4
Content available Influence of working position for thermal performance of the capillary heat pipe
Kosa L., Jobb M., Nemec P., Malcho M.
Structure and Environment
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2014
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Vol. 6, no. 1
46--48
EN
This experiment is concentrated on working position for optimization of capillary heat pipe. The main objective was to find optimal working position for capillary heat pipe. Working position is an important part for function of the heat pipe. A change in working position should change thermal performance of capillary heat pipe.
5
Content available Impact of the manufacturing conditions and operating position on heat transport ability of the heat pipe filled with Fluorinert FC-72
Čaja A., Nemec P., Mančikova V., Malcho M.
Structure and Environment
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2014
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Vol. 6, no. 2
44--47
EN
Heat pipes are devices, which transfer heat at a minimum temperature difference between evaporating and condensing phase. Operating temperature of heat pipe is determined by the working fluid and vacuum achieved during its production. This paper is focused on the determining the effect of the initial temperature of the ambient air to the performance characteristics of produced heat pipes. In general, the decrease in pressure decreases the boiling liquid. Based on this it can be presumed that achieving a lower temperature during production of heat pipe, the lower vacuum, the boiling point of working fluid while increasing ability of heat transport in various positions.
6
Content available Experimental determination of the working fluid volume for optimal function of the loop heat pipe
Hrabovský P., Nemec P., Malcho M., Jandačka J.
Structure and Environment
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2013
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Vol. 5, no. 4
29--31
EN
This experiment is concentrated on the working fluid of the heat pipe. The working fluid is an important part for the function of the heat pipe regarding the transfer of the heat. The measurements point out the appropriate quantity of the working fluid regarding the correct function of the loop heat pipe in the cooling of electronic components.
7
Content available Visualization of heat transport in heat pipes using thermocamera
Nemec P., Caja A., Lenhard R.
Archives of Thermodynamics
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2010
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Vol. 31, no. 4
125-132
EN
Heat pipes, as passive elements show a high level of reliability when taking heat away and they can take away heat flows having a significantly higher density than systems with forced convection. A heat pipe is a hermetically closed duct, filled with working fluid. Transport of heat in heat pipes is procured by the change of state of the working fluid from liquid state to steam and vice versa and depends on the hydrodynamic and heat processes in the pipe. This study have been focused on observing the impact these processes have on the heat process, the transport of heat within the heat pipe with the help of thermovision. The experiment is oriented at scanning the changes in the surface temperatures of the basic structural types of capillary heat pipes in vertical position.
8
Content available Evaluation of possibilities of CO2 geosequestration in geological structures of the Czech Republic
Bujok P., Nemec P., Nemec J., Konecny P.
Wiertnictwo, Nafta, Gaz
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2009
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T. 26, z. 1--2
107-117
EN
The present-day emissions of carbon dioxide (CO2) generated by anthropogenic activities and the expected future growing production of them are even now a serious ecological problem. One of possibilities of solving this situation is CO2 storage, i.e. the building of CO2 storage sites in suitable parts of the rock mass. They are represented, in addition to ideal localities, which are mined-out deposits of natural gas and oil, by selected geological formations of sedimentary Carboniferous deposits of hazd coal, it means localities of closed underground hard coal mines provided that they are ''tight'' enough. For the purposes of CO2 geosequestration, theoretically all closed hard coalfields exploited using the underground method in the Czech Republic can be considered, namely the Rosice-Oslavany (RUD), Kladno, Zacler-Svatonovice and Most Coalfields, and partial localities (closed mines) in the Czech part of Upper Silesian Hard Coal Basin (Ostrava-Karvina Coalfield). Of hydrocarbon deposits situated especially in the Vienna Basin, the Poddvorov, Nitkovice, Kostelany-vychod and Zdanice-zapad structures seem to be most promising.
PL
Obecne emisje dwutlenku węgla (CO2) pochodzenia antropogenicznego oraz przewidywany w przyszłości ich wzrost nadal stanowią problem ekologiczny. Jednym ze sposobów rozwiązania tego problemu jest magazynowanie CO2 tzn. budowanie miejsc magazynowania CO2 w nadających się do tego częściach górotworu. Należą do nich takie idealne miejsca, jak wyeksploatowane przestrzenie po produkcji gazu ziemnego i ropy naftowej, jak również niektóre formacje geologiczne, np. skały osadowe Karbonu z wyeksploatowanymi i odpowiednio szczelnymi złożami węgla kamiennego. Geosekwestracja CO2 wykonywana jest w zasadzie na wszystkich czeskich złożach węgla kamiennego eksploatowanych metodą podziemną, tj. Rosice-Oslavany (RUD), Kladno, Zacler-Svatonovice, w większości złóż, jak również w częściowo zlikwidowanych kopalniach czeskiej części Górnośląskiego Zagłębia Węglowego (Ostrava-Karvina). Spośród złóż zlokalizowanych w Basenie Wiedeńskim, najbardziej obiecujące wydają się być złoża Poddvorov, Nitkovice, Kostelany-vychod i Zdanice-zapad.
9
Content available remote Left Distributive Groupoids, Large Cardinals, and Laver Tables
Nemec P.
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
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2000/2001
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Vol. 8
51--56
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