Energy, economic and environmental analysis of opened natural healing water source

European´s low carbon economy is the main target in the way of the reducing greenhouse gases at the Earth´s atmosphere. The most promising way is in maximal usage of renewable sources of energy such as geothermal energy, which was in the year 2010 only 1 GWh at the Slovak republic. The paper refers to the detailed analyzation of the opened natural healing water system in the historical spa town Piešťany as one of the most perspective sources of the renewable energy in the Slovak republic primary used for healing procedures. Analysis is based on experimental measurement and numerical simulation of graphite block heat exchanger Korobon which was constructed in the year 1965 and resists highly mineralized water. The main function of this heat exchanger is to cool down the hot natural healing water with average temperature 60 °C to the 37 °C. The biggest impact is in the designing of new heat exchanger with the same quality properties as current one in accordance with the innovation of obsolete energy management at historical spa town. Such as solution allows us to save 5578 cubic meters of ground gas daily, necessary to be used for the same heat generation.


Introduction
The low-carbon economy belongs to the one of the biggest EU goal´s which the European commission is looking at. The roadmap suggest that, by 2050, the EU should cut its emissions to 80 % below the year 1990 levels through domestic reductions alone (i.e. rather than relying on international credits). This is in line with EU leader´s commitment to reducing emission by 80 -95 % by 2050 in the context of similar reductions to be taken by developed countries as a group. To reach this goal, the EU must make continued progress towards a lowcarbon society. Clean technologies play an important role. [1]

Slovakia -2020,2050 goals
The aim of Slovak politics is to use renewable sources of energy in ratio to gross final consumption of energy from 6, 7 % in 2005 to 14% till the year 2020. The essential document in relationship with reaching this goal is National action plan for energy from renewable sources of energy, which government granted at 6 th of October 2010, government resolution SR c. 677/2010. The resolution goal is to reach 15,3 % from the use of renewable sources of energy in ratio to gross final consumption of energy. The EU wants to decrease the number of greenhouse gases by 20 %, increase the energetic efficiency up to 20 % and use of renewable sources by 20 % till the year 2020 - Table 1. [3]  According to the conception of geological research and investigation at the territory of Slovak republic from the year 2011, Slovakia has a great energetic potential of the NHS. These renewable sources are split over the whole country and its using has economic and ecological benefits.
A technical exploitable potential of the individual renewable sources is shown at Table 2., where is although shown the energetic potential of the unused renewable sources, which could be used after the introduction of available technologies, breaking administration and ecological barriers. Nowadays we can say, that the most energetic potential has biomass (over 44 %), then the geothermal energy (16, 6%), the solar energy (13, 7%), the waste management (9, 3%), the biological fuels (6, 6%) and the wind energy (1, 6%). [7] The division of the geothermal sources at Slovakia is: [7] -Sources with low temperature from 20 o C to 100 o C -Sources with medium temperature from 100 o C to 150 o C -Sources with high temperature more than 150 o C The substantiality is given in ls -1 or m 3 h -1

Natural healing source as renewable source of energy in Slovak Republic
Currently the NHS energy is used at almost 40 locations and next 26 are considered to be new source of renewable energy (Fig. 2.). At the depth 1000 m under the therian level, should has the natural healing water temperature around θ = 40 °C, this fact influence the surface temperature. The water is getting into this depth primary by curtain from mountain ridges after rainfall. In Liptovský Mikuláš region reach the limestone mountains the depth around two kilometers and the water is naturally heated to the temperature θ = 60 -70 °C. [8]

Potential natural healing source of water at Slovak Republic
A Spa area is declared town territory or the part of town territory, on which are located the natural healing water sources, the natural healing spa, the healing spa and other devices necessary for providing healing procedures. [5] A Spa territory is comprehensive territory at the spa area, which size is defined in the statute of the spa area. At the spa area is applied protection of a spa regime. [5] The regulation No. 446/2006 Z.z. issued by the Slovak government were assigned statutes of the spa area, which can be seen in Table 2.2. with the resolution number of the Slovak government. At the Slovak Republic only this places are allowed to provide healing procedures by using natural healing sources. [5]

Piešťany -opened natural healing source of water
For the purpose of analysis, was chosen a small spa town Piešťany, located at the west side of Slovakia, 80 km from the capital city Bratislava (Fig.3.) Because of its good position from the Vienna International airport Schwechat-road distance 160 km and from Bratislava International airport -road distance 80 km, is visiting yearly by thousands of visitors and people willing to be curate.

Collection of natural healing water at Piešťany health spa
Collection of the natural healing water for the Balneotherapy departments is located at observed from historical point of view significant locations, where were by the long-term analysis detected the healing effects on a human organism. Mostly they are the natural seepage of the natural healing water source, which are collected and by the technological equipment transported to the Balneotherapy departments ( Fig. 4.). Analyzation of the natural healing sources at the Slovak Health Spa a.s. Piešťany has geological character, which describes the existing natural healing water system. This section is including in this diploma thesis as it is considered to be initial data for the elaboration complex analysis of the Balneotherapy. The analysis provide information about the temperature and the flow rate of individual natural healing water source, which is affected by the level of recipient and its flow rate regulation - Table 3.

Accumulation station
Due to the fact that the natural healing water has temperature cca. 65 °C at source, is useless for the healing procedures at the Balneotherapy departments and it is necessary to mixed it with the cooled NHS water. Mixing of the NHS water with another water e.g. from common well is not possible due to its mineral composition which will discard healing proposition of this water and cause its coloring. For this reason it is necessary to cooled down the NHS water collected from the natural healing water source.
From the source is the NHS water flow-through gravitationally collected at lower part of the accumulation station, where with the help of pumps is pressed into the opened distribution system. To secure required amount of the NHS in consideration of nonlinear requirement, there are situated horizontal tanks for the accumulation of at NHS at accumulation station. Nowadays Spa Piešťany owned 4pc. of an horizontal tanks for hot NHS and 6 pc. for cold NHS. The accumulation station has the biggest impact as concerning energetic, environmental and ecological point of view. Analysis of this object is the most important part, because all the Balneotherapy departments are supplied and depended on its operation.
Scheme 3.6. shows distribution of the natural healing water from drills V1,V4a,V8 and well Adam Trajan in bottom right corner at the accumulation station. The amount of water is on the base of the monitoring system of the Slovak Ministry of Health monitored and recorded. Average temperature of the natural healing water which is pumped into the water distribution system is 67 °C, which was obtained from long-term measurement. Part of the NHS water is flowing directly to the hot water distributor (marked with red color), from

Korobon -graphite heat exchanger
For ensuring the operation of the Balnotherapy in the SLKP a.s., the opened natural healing water system is complete with the distribution of cooled NHS water, which is prepared at the Korobon graphite block heat exchanger (see Scheme 3.10.

Temperature and flow rate experimental measurement
The experimental measurement of the NHS water at the Korobon graphite block heat exchanger was provided by the Comet data logger from 20.11.2016 to 11.03.2017 and was hold on the pipelines of the hot natural healing water (red color in scheme), the cooled natural healing water (green color in scheme), the hot service water (yellow color in scheme), the cold service water (blue color in the scheme) (Fig. 7.) After an consultation and technical decision there were four temperature sensors placed, one on each pipelines (see Fig. 7.). All sensors were insulated from outer influences with polystyrene th. = 40 mm, and the heat transfer area was increased with the help of aluminum foil in shape of U.

Simplified computer simulation of Korobon in ANSYS software
The computational analysis is provided on one unit of the Korobon heat exchanger, which was due to the academic license of the ANSYS Fluent software restriction in the amount of the computational ceils simplified. Thirdly the solution was evaluated in the ANSYS Fluent software with the boundary condition, which were obtained from the real operation of the Korobon heat exchanger:  Hot inlet temperature: 67 °C  Cold inlet temperature: 18 °C  Hot water flow rate: 13,03 l/s  Cold water flow rate: 13,3 l/s The graphical solution gives us view on the process at the Korbon heat exchanger unit during the operation and future possibility to determine critical states. A validation of calculated data is provided by thermography picture of the Korobon heat exchanger generated at the time of the boundary conditions (Fig. 8.) Fig. 9. Thermography picture of Korobon heat exchanger Based on the measured data, simulation and analysis it is possible to say that for operation of the Balnotherapy and other collection places, is necessary to accumulate 731,64 m 3 /day of the hot NHS water and 621,69 m 3 /day of the cooled NHS water. Current accumulation system -the Korobon heat exchanger is able to accumulate 489,26 m3/day of the cooled NHS water, which is less than total amount of the cooled NHS water daily used in operation of the Balneotherapy. This water amount difference is currently solved by the accumulation of cooled and hot NHS water in the accumulation tanks from where is transporting to the Balneotherapy in case of higher water amount demand.

Experimental solution of opened natural healing water system
The experimental solution in the vision of the accumulation station reconstruction at the Slovak Health Spa Piešťany a.s., within which the safety operation of the Balneotherapy should be increased, with the maximum usage of the NHS water and the hot service water energetic potential at the same time. This solution will leads to energy costs savings at operation of the Balneotherapy. For increasing the NHS cooled water amount with the temperature cca. 24 °C, will be flanged next heat exchangers at accumulation station. The number of heat exchanger will depend on the type of heat exchanger and expert decision of manufacturers. New heat exchangers will be situated at lower part of the accumulation station on concrete pads, on which are currently situated pumps and will be in parallel connection with the existing Korobon heat exchanger. Due to the fact of sedimentation the design of new heat exchanger is based on the assumption to be 100 % backup of the existing Korobon heat exchanger (Fig. 9.) The most important criteria in the design of accumulation station reconstruction was the ability of heat changer material to resist highly mineralized natural healing water. Due to this fact was chosen as the best material for future operation carbon fibers composite, similar to the existing one, which has been tested as a prototype for more than 50 years. The best variant was elaborated with the help of SGL Group Company, which is designer of the original placed block graphite heat exchanger Korobon. Technical specification is designed in the way of adding next 12 DIABON graphite groove heat exchangers parallel to the existing Korobon heat exchanger (Fig.10.).

Ecology and economic evaluation
The economic evaluation is based on compartment of the heat boiler room Balnea Centre with performance 9,98 MWh and the designed opened NHS water system - Table 4.4. and Table 4.5

Conclusion
Life environment is source of the all living species on the Earth. To ensure its quality and protection against the human factor the European Union accept several goals, such as the low-carbon economy, which should decrease amount of the Green House gases in the Europe by increasing the use of renewable sources. From applicability point of view the most uncommon renewable source in the Slovak republic is the natural healing source energy, which currently we are using only for healing purposes. Energy stored in the NHS systems due to its relatively high temperature has big energy potential, which can beneficially influence the economic and environmental situation in the Slovak republic.
The main goal of this analysis is to design the new technological devices to increase generation of the cooled NHS water, which will cover current insufficiency and allow the SLKP a.s. to provide expansion of the Balneotherapy. For this purpose were elaborated four variants and with the help of multiplecriteria decision chosen the one which will from energy, economic and environmental point of view be the most efficient.
The overall result is in form of the experimental calculation of the new technological devices connected to the existing opened NHS system. Firstly, it was proven, that decreasing the temperature of the cooled NHS water will leads to increasing the amount of used hot NHS water distributed directly from water source in the Balneotherapy departments. Secondly, new design technological devices will increase the amount of the saved gas necessary to heat water in the Balneotherapy departments and therefore help to the SLKP a.s. to fulfil the European Union lowcarbon economy.