CLAIMS
1. The invention is an under soil heating system which increases constant temperature of soil to high degrees by use of sun in summer and thus enables use of the heat energy stored under the soil later in particularly winter months for heating the enclosed locations and prevention of icing on roads, characterized in that it comprises;
- solar energy collectors (1 ) located on the surface of soil to collect the solar energy,
- a hot fluid tank (2) located under the soil, where the fluid heated inside the solar energy collector (1 ) is conveyed through connection components (4) by means of at least one pump (P1 ),
- a pipe system (3) providing heat storage in the soil, rock and saline masses through convection by means of hot fluid flowing inside and where the hot fluid stored inside the hot fluid tank (2) is conveyed through connection components (4) by means of at least one pump (P2).
2. An under soil heating system according to claim 1 wherein the vacuum tube solar energy collectors are used as solar energy collectors (1 ).
3. An under soil heating system according to claim 1 wherein the temperature of the hot fluid in the tank (2) is maximum 90 0 C - 99 0 C.
4. An under soil heating system according to claim 1 wherein the hot fluid tank (2) is a structure of reinforced concrete or plastic or metal basis, preferably located at least 4-5 m below the soil surface (5), inner, upper and side surfaces of the tank (2) are insulated against heat, no insulation is made in the lower surface of the tank (2) and heat transfer is left free in there.
5. An under soil heating system according to claim 1 wherein the fluid circulating in the system is a mixture of preferably water and engine oil.
6. An under soil heating system according to claim 5 wherein the fluid circulating in the system also consists anti-freeze in addition to water and engine oil.
7. An under soil heating system according to claim 1 wherein all connection components (4) connecting the solar energy collectors (1 ), hot fluid tank (2) and pipe system (3) have low heat conductivity coefficient for the parts remaining on soil and high coefficient for those remaining under the soil.
8. An under soil heating system according to claim 6 wherein the connection components (4) continuing on the soil or on surface are insulated with a material of high insulation value.
9. An under soil heating system according to claim 1 characterized in that under soil pipe system (3);
- starts from 3-5 m below the soil surface (5) and goes down up to 30-90 m deep,
- comprises several boreholes drilled in the soil and at least one fluid inlet and return pipe (3.1 , 3.2) providing return of the hot fluid to tank (2) after starting from the tank (2), extending to under-soil and transmitting its heat into soil and, having varying diameters depending on capacity of soil or rock to retain heat, located in each of the boreholes.
10. An under soil heating system according to claim 8 wherein inside of each borehole is filled with preferably C25 dose concrete and upper part thereof is insulated so as to not effect the natural life.
11. An under soil heating system according to claim 8 and wherein in case there is no water source and soil and rock ground is appropriate, the soil can store heat energy in saline mass in addition to energy to be stored by soil by help of saline filled into the new boreholes drilled between boreholes.
12. The invention is a method for realization of an under soil heating system which increases constant temperature of soil to high degrees by use of sun in summer and thus enables use of the heat energy stored under the soil later in particularly winter months for heating the enclosed locations and prevention of icing on roads and it is characterized in that it comprises the process steps of;
-heating of the fluid in the pipes (vacuum tubes) of the collector (1 ) by the solar energy collected by solar energy collectors (1 ),
-passing of the heated fluid through connection components (4) by means of at least one pump (P1 ) and conveyance of it to hot fluid tank (2) located under the soil,
- conveying of the heated fluid in the hot fluid tank (2) into under soil pipe system (3) installed under the soil, by means of at least one pump (P2),
- heating of the great amount of soil, rock and saline masses in contact with the pipe system (3) containing hot fluid circulation by the way of convection.
13. An under soil heating system according to claim 11 wherein the hot fluid in the tank (2) is transferred to under soil pipe system (3) after the temperature of the fluid in the hot fluid tank (2) reaches a certain level. |
UNDER SOIL HEATING SYSTEM AND METHOD
The Related Art
The invention relates to a under soil heating system wherein solar power accumulated by solar power collectors heats the fluid in the pipes (vacuum tubes) of the collector, the heated fluid is conveyed to a fluid tank located under soil via a pump station (or natural circulation), the hot fluid in the fluid tank is conveyed to under soil pipe systems of different diameter and length laid under the soil, by means of a pump, the land, rock and salt mass in contact with the pipe system containing hot fluid circulation is heated, and a method for realization of such system.
Background of the Related Art
Today various heating systems are used to heat particularly enclosed areas in winter months. The said systems usually use solid fuels, natural gas, electricity etc. as fuel source. Considering that CO 2 has been increasing fast and fossil fuels have been contaminating the world, use of the above fuel sources has big disadvantages. Use of electricity as fuel source causes great amount of power consumption as well as increase in costs. Use of natural gas for heating has been spreading more but natural gas reserve in the world has been decreasing and researches have been made to find and use new power sources. Solar energy is a power source which has been started to be used frequently recently and particularly water is heated by means of solar power collectors located on roofs of houses and the hot water provided by this way has been used for various purposes. However, the said collectors have been insufficient for heating the enclosed locations during winter months when the weather is not sunny.
Although there are not patent applications similar to the under soil heating system being disclosed under this invention, in patent application no JP58000059 the water obtained from stratum by means of double walled water pipe is conveyed to heat pump by means of a pump positioned at intermediate position of the water pumping pipe. The water heated therein is sent to a group of heat pipes to a heat plate and heats the plate. The energy of heated water is utilized for heating the enclosed locations and after utilization is returned to heating pump for circulation.
The patent no US4344414 discloses a system heating or cooling of buildings by use of solar energy. The system comprises a solar power collector connected to fluid thermal unit and having fluid pipes. Solar collector sends the collected heat to the storage under the ground. Thermal unit provides fluid convection between parts of the unit surrounded by lower and upper heat transfer jacKets. A heat pump is located in the building which is to be heated or cooled. Heat pump contains pipes for fluid circulation between lower and upper heat transfer jackets of embedded thermal unit and head pump. An alternative embodiment of the system can be utilized to thaw frozen ground by use of thermal units consisting of only lower heat transfer jackets.
Patent application no. US4184477 discloses a system for utilizing solar energy which includes the use of solar collectors attached to liquid tubes or heat pipes. The heat produced by heating the liquid in the fluid pipes by solar energy is stored in earth ground for auxiliary and long-term uses. Heat transmission pipes are used to distribute the heat into big volume area under soil and the heat is extracted for use when required. This application relates to a system providing long-duration storage of heat energy under soil and allowing use of it as independent heating source, particularly for meeting hot water and heating needs in houses, official and private buildings, swimming pools etc. However, the system consists of a complex embodiment consisting of several parts such as evaporator, condenser etc. and provides convection heating of mass land, rock and saline masses in contact with the pipe system where hot water is circulated, and provides a solution for re-use of heat stored in the soil during particularly winter months.
As it will be seen when the above systems are examined, they do not provide a solution such as heating enclosed locations, frozen roads and airport runways by use of heat energy produced by heating soil, rock and saline masses and collected therein during particularly winter months.
Purpose of the Invention
The purpose of the invention is to disclose an under soil heating system wherein solar power accumulated by solar power collectors heats the fluid in the pipes (vacuum tubes) of the collector, the heated fluid is conveyed to a fluid tank located under soil via a pump, the hot fluid in the fluid tank is conveyed to under soil pipe
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systems of different diameter and length laid under the soil, by means of a pump, the land, rock and salt mass in contact with the pipe system containing hot fluid circulation is heated by convection and the heat energy stored under soil can be used to provide heating of enclosed locations particularly in winter months, to prevent icing on airport runways or roads.
The under soil heating system being subject of the invention increases constant temperature of soil of 13-15 0 C to 90 0 C by use of solar energy and thus enables use of the heat energy stored under the soil later in particularly winter months for heating the enclosed locations and prevention of icing on roads.
The main purpose of the invention is to realize a system by use of several articles and devices used at present but use thereof together not considered and also by applying a system not applied before. This embodiment will decrease import of energy by means of natural sources and provide an important step for prevention of distortion of development and natural balances.
Another purpose of the invention is to provide much more energy production by consumption of less energy while CO 2 increases fast and fossil fuels contaminate the world. More importantly, the under soil heating system being subject of this invention prevents emission of harmful gas into nature as carbon dioxide and fossil fuels will not be used.
The energy needed for operation of the system is illumination energy of a few hundred Watts in electricity energy. Operation of under soil heating system is provided by means of a solar battery support of one or two Kw to be installed, without need for any power from outside, and for instance, needs of 50 or 100 apartments are met.
If it is considered that only five million families use this system for heating, the saving to be made because of not using natural gas will be about five billion dollars a year. This figure will increase much more when official departments and industry is taken into consideration. Thus carbon release of Turkey will decrease under half of the present value.
The under soil heating system has the following advantages and fields of utilization.
a) Under soil heating system can be used to meet heating needs and hot water needs of detached, single-storey and multi-storey houses.
b) When it is decided to use this method, for instance, while constructing foundation Works of a building planned to have 50 flats, instalment of the system and insulation will provide decrease in costs. Constructional rigidity of under soil heating system will also contribute to compression and rigidity of the ground of the construction to be performed. Thus, hot water and heating costs of the flats will be almost zero. When the costs close to zero is also supported with a solar battery of 1 - 1 ,5 Kwh, the system will operate automatically, including illumination but except maintenance and repair costs.
c) Heating of water at existing hotels, hammams and thermal facilities can also be provided by use of this system. Moreover, thermal tourism can be supported by means of providing new thermal facilities by heating high quality cold spring water without having hot water source.
d) Green houses can be constructed in any climates and high efficiency and revenue can be provided by Use of under soil heating system. Thus, great opportunities are created for ecological cultivating.
e) Under soil heating system can be installed at airport runways, highways. The system can be installed at the highway points where traffic accidents occur due to icing on in-city and inter-city highways and thus traffic accidents can be prevented. Thus the burdens caused by casualty and injuries and disabilities.
f) The system may operate efficiently for several years in any fields of industry where hot water is needed and thus CO 2 release is reduced as well as costs are decreased.
g) Use of the system during constructing all public buildings such as hospitals, schools, military stations and facilities or later will provide great contribution to government budget and also a great contribution to/solution to CO2 release problem of Turkey and the world will be provided.
In order to achieve the said purposes:
The invention has been developed as an under soil heating system which increases constant temperature of soil to high degrees by use of sun in summer and thus enables use of the heat energy stored under the soil later in particularly winter months for heating the enclosed locations and prevention of icing on roads and it is characterized in that it consists of;
- Solar energy collectors located on the surface of soil to collect the solar energy,
- a hot fluid tank located under the soil, where the fluid heated inside solar energy collector is conveyed through connection components by means of at least one pump,
- A pipe system providing heat storage in the soil, rock and saline masses through convection by means of hot fluid flowing inside and where the hot fluid stored inside the hot fluid tank is conveyed through connection components by means of at least one pump.
The structural and characteristics features of the invention and all advantages will be understood better in detailed descriptions with the figures given below and with reference to the figures, and therefore, the assessment should be made taking into account the said figures and detailed explanations.
Description of Figures
Figure 1 Shows schematic view of under soil heating system being subject of the invention.
Figure 2 Shows overall perspective view of under soil heating system being subject of the invention.
Figure 3 Shows perspective view of fluid inlet and return pipes of the pipe system.
Figure 4 Shows perspective view of the mounted position of pump and connection components.
Reference Numbers
1. Solar energy collectors
2. Hot fluid tank
3. Pipe system
3.1 Fluid inlet pipe
3.2 Fluid return pipe
4. Connection component
5. Soil surface
P1 Pump
P2 Pump
Detailed Description of the Invention
The invention relates to a under soil heating system wherein solar power accumulated by solar power collectors (1 ) heats the fluid in the pipes (vacuum tubes) of the collector (1 ), the heated fluid is conveyed to a fluid tank (2) located under soil via a pump (P1 ), the hot fluid in the hot fluid tank (2) is conveyed to under soil pipe systems (3) of different diameter and length laid under the soil, by means of a different pump (P2), the land, rock and salt mass in contact with the pipe system (3) containing hot fluid circulation is heated by way of convection, and a method for realization of such system.
Preferably high efficient, vacuum tube solar collectors are used as solar energy collectors (1 ). The hot water supplied to the hot fluid tank (2) constructed under soil from the said collectors is conveyed there by means of a pump (P1) and heated. The temperature of the hot fluid in the tank (2) ranges between maximum 90 0 C and 99 0 C. After the temperature of the hot fluid in the tank (2) exceeds a certain limit, hot fluid in the tank (2) is conveyed into under soil pipe system (3) and soil mass is heated by means of convection. Various sensor means such as sensor and thermostat can be used to measure the temperature of and changes in temperature of the fluid in the
tank (2). As the heat transmission coefficient of soil, rock and saline masses is too low, the heat energy stored therein can be used again to heat the enclosed locations or prevent icing on the roads particularly in winter. The hot fluid flowing in the pipe system (3) in contact with soil transmits its heat into soil and then returns to the hot fluid tank (2), and mixes with hot fluid there and after achievement of high temperature again, is sent to pipe system (3) through pump (P2) and can be used. In other words, constant circulation in the system is provided. Particularly in winter months when the weather is not sunny, the fluid in the tank is heated by means of the heat energy stored in the soil mass and the fluid in the tank (2) is used to heat enclosed locations such as houses and to prevent icing on roads. The hot water heated in solar energy collectors (1 ) passes through pump (P1 ) and connection components (4) and is conveyed to the hot fluid tank (2). The fluid in the hot fluid tank (2) is conveyed to under soil pipe system (3) by means of a different pump (P2) and huge soil, rock and salt masses are heated by the hot fluid passing through the pipes and heat energy is stored in such masses of low heat transmission coefficient.
The said tank (2) contains hot fluid of maximum 90 0 C - 99 0 C temperature. The hot fluid in the tank (2) is sent by means of a pump (P2) into the pipe system (3) laid in a manner extending from soil surface (5) downwards and thus circulation thereof in the said pipe system (3) is provided. The hot fluid circulating in the pipe system (3) is used to heat great volume of soil, rock and salt masses by means of convection. The system operates fully in closed circuit. The pipe system (3) consists of several pipes laid one by one and preferable is 30-90 m. deep from soil surface (5) downward.
Upon a certain capacity of consumption, it is designed in a manner the temperature of tank (2) remains minimum at 40 0 C and maximum 99 0 C.
The annual targeted energy values for the soil heating system and values for parts forming the system are given the table below.
Total energy return of 630 m 3 for soil a year and 70 m 3 for salt a year and in total:
19.600.000 + 14.875.000 = 34.475.000 Kcal.
However, this amount can be increased to about 62.125.000 Kcal/year in a couple of years with lateral and downward heating.
All calculations has been made on assumption that constant temperature of soil and water is13-15 0 C. This value may vary depending on regions.
Hot Fluid Tank:
The tank (2) should be located at least 4-5 m under the soil surface (5). Upper and side surfaces of the hot fluid tank (2) have been insulated against heating. Lower surface of the hot fluid tank (2) facing downward the soil has been left heat transfer free. In other words, no insulation has been made. Hot fluid tank (2) is preferably reinforced building of 2 x 4 x 1 ,5 m size and 12.000 It capacity in the illustrative example. Hot fluid tank (2) can also be made of plastic or metal materials. Internal surface has been sealing insulated. The deep of the hot fluid tank (2) to soil surface should be increased if there are trees around and plants of deep root that can be influenced by the heat.
The tank (2) shall be capable to store about 12 m 3 water x 1000 Kcal x 85 0 C = 1.020.000 Kcal
The bigger the tank is the easier is to receive and send energy. This value can be increased or decreased depending on desired temperature level of the energy to be consumed.
Hot fluid tank (2) can also be built in a size capable to store up to targeted 47.250.000 Kcal energy. However, in this case, it would be required to build a tank (2) capable to intake 555 tons water. In this case, as the tank (2) to be built must be durable against earthquake, the cost may increase.
Solar Energy Collectors:
In the illustrative system:
Solar energy collectors of average 70.000Kcal/h capacity are needed as solar energy collectors (1) for about 200 sunny days.
Annually, approximately,
It meets energy need of
70.000 Kcal/h x 5 hours/day x 200 sunny days = 70.000.000 Kcal/year.
One of the reasons for preferring vacuum type collectors is that round tubes are more convenient for angle of taking sun during the sun's day time movement. The said collectors can be dimensioned according to the location and position of mounting. The collectors have been used most commonly in all over the world. In this case, available solar energy collectors providing the same capacity can also be used in project.
By means of increasing the number of collectors, the targeted energy sum can be exceeded by obtaining efficiency from burning sun in spring months close to level in summer months.
Considering that collectors can collect energy by day light even when the weather is not sunny, this energy can be used to perform works requiring less heat difference, lower heat requiring works such as heating green houses and swimming pools.
The fluid transferring heat from collector to tank (2) and conveying the energy transferred to earth is mixed with engine oil at 20% rate. This provides long life of galvanized under soil heating system as well as increases viscosity and therefore facilitates transmission. Pe or pprc pipes bent in helix of capacity providing same heat conductivity can also be used instead of galvanized pipe.
However, in this case, as the viscosity will decrease and friction will increase, the pressure should be increased. And this means additional electricity consumption.
Under Soil Pipe System:
Illustrative system:
Under soil pipe system (3) starts 3 - 5 meters below the soil surface (5). For this system, preferably 21 boreholes of 20 - 40 cm (or bigger) diameter, 30 m. deep (or the deeper it is the more energy is to be stored) are drilled. Then, cage manufactured of steel bars tied with stirrup will be prepared. After that, one fluid outlet pipe (3.1 ) carrying hot fluid beneath the soil and a fluid return pipe (3.2) carrying the fluid exchanging heat with soil into hot fluid tank (2) are located into the cage. Diameters and types of fluid outlet and return pipes (3.1 , 3.2) can vary according to the capacity of soil or rock to retain heat. This system can be prepared outside and in parts of six meters.
This steel mesh and pipe system are connected in parts and downed into the borehole. Then the cover thereof is filled with at least C25 dose concrete with increased heat permeability coefficient. The number of reinforced concrete tube system of 30 m depth to be used in the system is 21. In cases where there is no water source, where it is not used, and when the soil and rock ground is also convenient, saline of solid phase is filled into the new boreholes of 40 or 50 cm diameter to be drilled between the said 21 -concrete bar system and the heat capacity of the system is increased much more. After filling saline under the soil, it turns into liquid because of high temperature. Saline can store heat energy eight times more than rock and 2,5 times more than water. In this case, by filling salt into 12 saline boreholes of 50 cm diameter drilled between 21 tube bar system 70 m 3 saline stores an amount of energy to be stored by 560 m 3 in addition to the amount to be stored by
630 m 3 soil.
In appropriate geographical and structural conditions, the same system can be constructed in any geometrical form and number into mountain by means of rotary excavators of horizontal, lateral or 12 inch or different diameters.
Inlet and return pipes at one meter distance on upper part are connected to hot water tank via a pump (P2) also supported with valves to turn on and off when required, by use of convenient connection components (4) of low heat permeability coefficient and insulation and thus conduction and convection of heat into earth is provided. Upper surface of these parts, including pipes should be insulated. The area required for entire of this system is 21 m 2 but the area where to be insulated must be at least 3-4 times of that area. A layer should be provided with pumice or pearlite starting from 3 - 5 meters under the surface and water drainage must be constructed. Other insulation materials may also be used in this part. It should be covered with the soil enabling continuation of natural life.
In regard to soil (rock), the area to be heated is,
3 m x 7 m =21 m 2
At depth of 30 m,
21 m 2 x 30m = 630m 3
630m 3 / 3,2 = 196 m 3 (equivalence in water)
196m 3 x 10OOKcal x (15° C +85° C) = 19.600.000 Kcal/year.
Capacity of rock to retain heat is 1/3,2 times of capacity of water. This capacity increases when the rate of water or rock density increases. The calculations are made on bases of rock.
As the under soil pipe system (3) will heat its own volume in initial year, its capacity to retain heat will be equal to its volume. As the rock is of property to retain heat equal to 1/3,2 of the water, only that amount of targeted energy can be obtained. However, in the following years spreading to four directions and downward will occur and it will retain heat equal to at least four-five times of the volume, the targeted
energy can be stored in the under soil system. In the years thereafter, the efficiency may even exceed the expected level of 47.250.000 Kcal/ year.
As explained above, when saline bars (bags) are added to the system, 70 m 3 of salt will provide additional 85 0 C x 1000 Kcal x 2,5 times of water x 70 m 3 = 14.875.000 Kcal energy storage.
Even when considering soil not exceeding temperature of 90 C, the reduction of rock and soil to be removed to put salt instead and calculating other loss, still sufficient energy would be gained to reach the heating purpose
Connection Component:
All connection components (4) connecting the solar energy collectors (1 ), hot fluid tank (2) and pipe system (3) should be selected in a manner providing low heat conductivity coefficient on soil and high coefficient under the soil. The connection components running on soil or on surface should be insulated with material of high insulation value. The purpose of high conductivity under soil is to facilitate heat exchange under the soil. Another purpose is to not lose heat on the soil. For that reason, transmission and connection components should also be insulated with material of low heat transmission coefficient.
The Matters to be Taken into Consideration:
One of the important matters to be taken into account for under soil heating system is the underground water. As underground water would take the heating energy away, measurement should be made before installation of the system and investment should be initiated after discovery of no nearby water sources causing heat transfer.
If the water sources discovered during measurement can be extracted onto the ground in the form of spring, it can be a matter to be assessed separately as artificial underground hot water source.
Selection of location is one of the most important issues. If possible, the area where the system will be installed should be land of minimum 5-10% slope. If the sloppy area faces south, it can provide an advantage if not much, in terms of sunlight and provides natural circulation of heat transfer between solar energy collector (1) and hot water tank (2) and thus provides energy saving.
Although the high efficiency is not achieved in terms of reaching optimum level of energy accumulation in the initial years, the intended result will be achieved starting from second year as a result of heating of land and neighbourhood where the system is installed.
One of the most important matters is insulation. Heating of on-surface of the soil by the under soil system and tank (2) should be prevented. It will cause heat loss as well as effect the life of plants, animals and micro-organisms on the soil.
For that reason, all of the area where heat loss is likely to occur should be firstly covered with materials such as pearlite, pumice, the required drainage and ground water leakage preventing measures should be taken and then should be covered with soil again and surface should be left for natural life.
Costs
Tank 10.000 YTL
Under soil system: 40.000 YTL Connections: 5.000 YTL
Total: 55.000 YTL
Costs may be perceived differently subject to condition of the place, type of construction and requirement priorities.
The period of investment return is 5 (five) years based on the coarse calculations given above.
This project is feasible and applicable for Turkey between 36 and 42 latitudes as this area has sufficient sunny days. However, when considered in terms of cost-benefit, when price of oil per barrel goes over 80 and 100 dollars, installation of the system will be much more profitable.
When the damage caused to world by fossil fuels are taken into consideration, when cut of natural gas in winter months is considered, the risks of gas leakage and explosion thereof because of being a country under earthquake risk and investments made to supply it to consumer all make the project applicable.
Other than all of those, it is no doubt that the energy whose source is not abroad but in our country is the most important factor for us in strategic terms.
As there will not be investment from energy source to consumption point and investment in devices required for utilization of this energy in regard to he under soil heating system, the government may distribute such costs incurred by it to provide establisher power to the investor as incentive.
Some European Union Member States grant 3500 Euro state aid and 3500 Euro long term loan for projects amounting to 7.000 Euros and try to ensure less Electric consumption from interconnection system provided that solar battery systems capable to produce daily 1 ,5 - 2 Kwa/h energy are installed in the houses.
In case government supports the under soil heating system in our country by means of a similar incentive system, new thermal or nuclear power plant investments will not be needed.