KR20210094796A - Coaxial type geothermal heat exchanging system - Google Patents

Abstract

The present invention relates to a coaxial type underground heat exchange system. According to the present invention, the coaxial type underground heat exchange system performs heat exchange with a first heat exchanger on the ground by circulating the heat exchange water in a double pipe including an outer pipe is spaced apart and inserted into an inner surface of an underground hole formed in the ground, and an inner pipe which is spaced apart into the outer pipe. The underground heat is transferred to the outer pipe by the groundwater filled in a filling space between the underground hole and the outer pipe.

Description

Double tube type underground heat exchange system {COAXIAL TYPE GEOTHERMAL HEAT EXCHANGING SYSTEM}

The present invention relates to a double tube type underground heat exchange system, and more particularly, to a double tube type underground heat exchange system for transferring heat in the ground by circulating heat exchange water through a double tube composed of an outer tube and an inner tube.

In general, fossil fuels such as petroleum, coal, natural gas, etc. are directly used as energy for heating and cooling, or electric energy produced on a large scale in a thermal power plant or a nuclear power plant is used. As such, the method of using fossil fuels or nuclear fuels causes environmental pollution problems and has problems in that fuel materials are gradually depleted.

Accordingly, in recent years, development of alternative energy using natural energy such as wind power, solar heat, geothermal heat, etc. is actively progressing to replace it. Such natural energy has the advantage of obtaining infinite energy without causing environmental pollution, but it is an important problem to convert it into a usable form by maximizing it as the energy density is low.

Among the technologies using natural energy, an underground heat exchange system using thermal energy in the ground with a temperature of 10 to 20 °C is known. The underground heat exchange system is an open type (including semi-open SCW (Standard Column Well) method) that raises groundwater located about 500 m underground and directly exchanges heat with an above-ground heat exchanger (including a semi-open SCW (Standard Column Well) method), and a constant ( Water) or antifreeze is circulated to indirectly heat exchange in a heat exchanger on the ground. It is known that the vertical sealed type accounts for about 65% of the underground heat exchange systems that are currently in practical use.

The conventional double tube type underground heat exchange system among the vertical sealed type forms a double tube 20 composed of an outer tube 22 and an inner tube 24 in the underground hole 10 drilled to a predetermined depth as shown in FIG. 1 . and install the heat exchanger 30 and the pump 40 on the circulation pipe 50 on the ground extending from the double pipe 20 to circulate the heat exchange water inside the double pipe 20 and transfer the heat energy of the heat exchange water to the heat exchanger 30 ) to the ground through At this time, the space between the underground hole 10 and the double pipe 20 (more precisely, the outer pipe 22) is grouted using bentonite or cement to transfer the thermal energy of the underground to the double pipe 20.

However, the conventional grout 60 constructed of cement or the like has a low thermal conductivity, so there is a problem that the depth of the underground hole 10 or the number of the underground hole 10 must be increased in order to increase the energy density.

Republic of Korea Patent Registration No. 10-1061494

Accordingly, an object of the present invention is to solve such a conventional problem, and to provide a double tube type underground heat exchange system with high heat transfer efficiency by filling the filling space between the underground hole and the double tube with groundwater to transfer the underground thermal energy.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The above object is, according to the present invention, by circulating heat exchange water in a double pipe including an outer pipe spaced apart inserted into the inner surface of the underground hole formed in the ground and an inner pipe spaced apart into the outer pipe to be inserted into the first heat exchanger on the ground and In the coaxial type underground heat exchange system for performing heat exchange, the double tube type underground heat exchange system that transfers heat from the underground to the outer tube by the groundwater filled in the filling space between the underground hole and the outer tube To be achieved by can

Here, it may further include a circulation unit for circulating the groundwater filled in the filling space.

Here, the circulation unit is inserted into the filling space, the circulation inlet pipe (inlet pipe) for sucking the groundwater; a circulation outlet pipe inserted into the filling space and re-supplying groundwater sucked by the circulation inlet pipe to the filling space; and a first pump disposed between the circulation inlet pipe and the circulation outlet pipe.

Here, the circulation withdrawal pipe may be formed to extend to the lower end of the filling space.

Here, it may further include a gas supply unit for supplying a high-pressure gas to the groundwater filled in the filling space.

Here, the gas supply part is inserted into the filling space, a gas supply pipe for supplying gas; and a second pump for discharging high-pressure gas to the gas supply pipe.

Here, the gas supply pipe may be formed to extend to the lower end of the filling space.

The above object, according to the present invention, the first underground heat exchange system of any one of the above-mentioned double tube type underground heat exchange system; The second underground heat exchange system of any one of the above-mentioned double tube type underground heat exchange system; and an underground water transfer unit configured to supply groundwater filled in the filling space of the first underground heat exchange system to the filling space of the second underground heat exchange system to form a hydraulic pressure difference between the two filling spaces. can

Here, the groundwater transfer unit is a transfer inlet pipe inserted into the filling space of the first underground heat exchange system to suck the groundwater; a transfer outlet pipe inserted into the filling space of the second underground heat exchange system to supply groundwater sucked in by the transfer inlet pipe; and a fourth pump disposed between the transfer inlet pipe and the transfer outlet pipe.

Here, the transfer withdrawal pipe may be formed to extend to the lower end of the filling space of the second underground heat exchange system.

Here, it may further include a second heat exchanger for performing heat exchange from the groundwater transferred by the groundwater transfer unit.

According to the double tube type underground heat exchange system of the present invention as described above, there is an advantage that the heat transfer efficiency of underground thermal energy can be increased by filling the filling space between the underground hole and the double tube with groundwater having high thermal conductivity.

In addition, there is an advantage in that the heat transfer efficiency can be maximized by the advection effect by artificially circulating the groundwater filled in the filling space.

In addition, there is an advantage that heat transfer efficiency can be maximized by the bubble convection effect by supplying high-pressure gas to the lower end of the filling space.

In addition, by installing a plurality of underground heat exchange devices and transferring the groundwater filled in the filling space of one underground heat exchanger to the filling space of the other underground heat exchange device, a pressure difference between the filling spaces is generated to induce the flow of groundwater in the aquifer. , there is also an advantage that the underground heat exchanger can be used for a long time.

1 is a view showing a conventional double tube type underground heat exchange system.
2 is a view showing a double tube type underground heat exchange system according to a first embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along line AA of FIG. 2 .
4 is a view showing a double tube type underground heat exchange system according to a second embodiment of the present invention.
5 is a view showing a double tube type underground heat exchange system according to a third embodiment of the present invention.
6 is a view showing a double tube type underground heat exchange system according to a fourth embodiment of the present invention.
7 is a view showing a double tube type underground heat exchange system according to a fifth embodiment of the present invention.

The specific details of the embodiments are included in the detailed description and drawings.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, the present invention will be described with reference to the drawings for explaining a double tube type underground heat exchange system according to embodiments of the present invention.

2 is a view showing a double tube type underground heat exchange system according to a first embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line AA of FIG. 2 , and FIG. 4 is a double tube type underground heat exchange system according to a second embodiment of the present invention. It is a view showing a heat exchange system, FIG. 5 is a view showing a double tube type underground heat exchange system according to a third embodiment of the present invention, and FIG. 6 is a view showing a double tube type underground heat exchange system according to a fourth embodiment of the present invention 7 is a view showing a double tube type underground heat exchange system according to a fifth embodiment of the present invention.

The underground heat exchange system according to the first embodiment of the present invention is a double tube type in which a double tube 120 formed of an outer tube 122 and an inner tube 124 is inserted into the underground hole 110 drilled to a depth of 100m to 200m. (Coaxial type) It relates to a heat exchange system.

Heat exchange water formed of water or antifreeze is filled in the double pipe 120 and circulated to the ground, and heat exchange is performed for heating and cooling through a heat exchanger located on the ground.

The lower end of the outer tube 122 is formed in a closed shape, and the lower end of the inner tube 124 is installed to be spaced apart from the lower end surface of the outer tube 122 by a predetermined distance, so that the inner tube 124 is operated by the pump 140 . ) through the double pipe 120, it is possible to raise the heat exchange water at the lower end to the ground. A heat exchanger 130 is formed on the ground circulation pipe 150 extending from the inner tube 124 , and the heat exchange water that has undergone heat exchange through the heat exchanger 130 is the inner tube 124 and the outer tube 122 . It is re-supplied to the space between them and circulated.

The double pipe 120 is formed of a material such as PVC, but is not necessarily limited thereto. Also, the inner tube 124 and the outer tube 122 may be formed of materials having different thermal conductivity. For example, the outer tube 122 may be formed of a material having high thermal conductivity, and the inner tube 124 may be formed of a material having a relatively low thermal conductivity.

At this time, the outer tube 122 is spaced apart from the inner surface of the underground hole 110 to form a filling space 160 between the underground hole 110 and the outer tube 122. In the present invention, the filling space ( 160) is filled with groundwater (water). By using groundwater instead of the conventional grout, it is possible to increase the heat transfer effect of transferring the underground heat to the inside of the double pipe 120 . Accordingly, it is possible to increase the energy density of the underground heat exchange system.

Groundwater itself has a high thermal conductivity, and furthermore, when water has a temperature difference between the upper and lower parts, natural convection occurs and the heat transfer effect by flow can be increased.

The double tube type underground heat exchange system according to the second embodiment of the present invention is a circulation unit that circulates the groundwater filled in the filling space 160 in the first embodiment described with reference to FIGS. 2 and 3 as shown in FIG. 4 . (170).

The circulation unit 170 may include a circulation inlet pipe 172 , an outlet pipe 174 , and a pump 176 . The circulation inlet pipe 172 is inserted into the upper end of the filling space 160 to suck the groundwater filled in the filling space 160 , and the circulation withdrawal pipe 174 is formed to extend to the lower end of the filling space 160 , and the circulation inlet pipe The groundwater sucked through 172 is re-supplied toward the filling space 160 again. At this time, a pump 176 is formed between the circulation inlet pipe 172 and the circulation outlet pipe 174 to circulate the groundwater filled in the filling space 160 .

Therefore, in the present invention, by forcibly circulating the groundwater in the filling space 160 by the circulation unit 170, the heat transfer effect can be maximized by the advection effect. In particular, in the present invention, groundwater is re-supplied from the lower end of the filling space 160 through the circulation withdrawal pipe 174 extending to the lower end of the filling space 160 to form a flow to the upper end of the groundwater supplied to the lower end, and heat transfer effect to make it higher.

As shown in FIG. 5, the double tube type underground heat exchange system according to the third embodiment of the present invention provides high-pressure gas to the groundwater filled in the filling space 160 in the first embodiment described with reference to FIGS. 2 and 3 . It further includes a gas supply unit 180 for supplying.

The gas supply unit 180 may include a gas supply pipe 182 and a pump 184 . The gas supply pipe 182 is formed to extend from the ground to the lower end of the filling space 160 and fills the high-pressure gas supplied by the (gas supply) pump 184 located on the ground through the gas supply pipe 182 . It is supplied to the lower end of the space 160 . At this time, the gas may be composed of general air, carbon dioxide, nitrogen, etc., but is not limited thereto.

Therefore, in the present invention, by supplying high-pressure gas to the lower end of the filling space 160 by the gas supply unit 180, bubbles are generated in the groundwater, and bubble convection is generated in the process of moving upward and collapsing. By this effect, the heat transfer effect can be further enhanced.

The double tube type underground heat exchange system according to the fourth embodiment of the present invention is the circulation unit 170 of FIG. 4 and the gas of FIG. 5 in the first embodiment described with reference to FIGS. 2 and 3 as shown in FIG. By forming the supply unit 180 at the same time, the forced flow of groundwater is maximized to further enhance the heat transfer effect.

The double-tube type underground heat exchange system according to the fifth embodiment of the present invention includes the double-tube type underground heat exchange system 200a and 200b described above with reference to FIGS. 2 to 6 as shown in FIG. 7, and the second and a groundwater transfer unit 190 for supplying the groundwater filled in the filling space 160 of the first underground heat exchange system 200a to the filling space 160 of the neighboring second underground heat exchange system 200b.

The groundwater transfer unit 190 is inserted into the upper end of the filling space 160 of the first underground heat exchange system 200a to suck in the groundwater, the transfer inlet pipe 192, and the filling space 160 of the second underground heat exchange system 200b. ) is inserted into the transfer inlet pipe 192 to supply groundwater sucked from the filling space 160 of the first underground heat exchange system 200a to the filling space 160 of the second underground heat exchange system 200b through the transfer inlet pipe 192. It may be configured to include a pump 196 disposed between the pipe 194 and the transfer inlet pipe 192 and the transfer outlet pipe 194 to move the groundwater.

At this time, the transfer take-off pipe 194 is formed to extend to the lower end of the filling space 160 of the second underground heat exchange system 200a, so that the heat transfer effect can be enhanced as described with reference to FIG. 4 .

As a part of the groundwater filled in the filling space 160 of the first underground heat exchange system 200a is transferred to the filling space 160 of the second underground heat exchange system 200b by the groundwater transfer unit 190, two filling spaces A water pressure difference between 160 is generated. This makes the flow of groundwater more active through the aquifer formed underground between the two heat exchange systems 200a and 200b.

If the underground heat exchange system is used for a long period of time, the temperature difference between the underground and the ground gradually becomes smaller, and the efficiency may decrease. However, as in the present invention, the temperature difference between the ground and the ground can be maintained by the groundwater moved through the aquifer, so that the underground thermal energy can be used with high efficiency for a long time.

Although not shown, a heat exchanger (not shown) may be additionally installed on the path through which the groundwater moves through the groundwater transfer unit 190 to directly exchange heat with the groundwater.

In addition, although not shown, a groundwater transfer unit 190 for moving groundwater from the second underground heat exchange system 200b to the first underground heat exchange system 200a may be additionally formed.

The scope of the present invention is not limited to the above-described embodiments, but may be implemented in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the present invention claimed in the claims, it is considered within the scope of the description of the claims of the present invention to various extents that can be modified by any person skilled in the art to which the invention pertains.

110: underground
120: double pipe
122: exterior
124: inner tube
140: pump
150: circulation pipe
160: filling space
170: circulation unit
172: circulation inlet piping
174: circulation withdrawal pipe
176: pump
180: gas supply unit
182: gas supply pipe
184: pump
190: groundwater transfer unit
192: transfer inlet pipe
194: transfer take-off pipe
196: pump
200a: first underground heat exchange system
200b: second underground heat exchange system

Claims (11)

A coaxial type that performs heat exchange with a first heat exchanger on the ground by circulating heat exchange water in a double pipe including an outer pipe spaced apart and inserted into the inner surface of the underground hole formed in the ground and an inner pipe spaced apart into the outer pipe ) in the underground heat exchange system,
A double tube type underground heat exchange system for transferring underground heat to the outer tube by groundwater filled in the filling space between the underground hole and the outer tube. The method of claim 1,
The double tube type underground heat exchange system further comprising a circulation unit for circulating the groundwater filled in the filling space. 3. The method of claim 2,
the circulation part
a circulation inlet pipe inserted into the filling space to suck the groundwater;
a circulation outlet pipe inserted into the filling space and re-supplying groundwater sucked by the circulation inlet pipe to the filling space; and
and a first pump disposed between the circulation inlet pipe and the circulation outlet pipe. 4. The method of claim 3,
The circulation withdrawal pipe is a double tube type underground heat exchange system that is formed to extend to the lower end of the filling space. The method of claim 1,
The double tube type underground heat exchange system further comprising a gas supply unit for supplying high-pressure gas to the groundwater filled in the filling space. 6. The method of claim 5,
The gas supply unit
a gas supply pipe inserted into the filling space to supply gas; and
and a second pump for discharging high-pressure gas to the gas supply pipe. 7. The method of claim 6,
The gas supply pipe is a double tube type underground heat exchange system that is formed to extend to the lower end of the filling space. A first underground heat exchange system according to any one of claims 1 to 7;
A second underground heat exchange system according to any one of claims 1 to 7; and
and an underground water transfer unit configured to supply groundwater filled in the filling space of the first underground heat exchange system to the filling space of the second underground heat exchange system to form a hydraulic pressure difference between the two filling spaces. 9. The method of claim 8,
The groundwater transfer unit
a transfer inlet pipe inserted into the filling space of the first underground heat exchange system to suck groundwater;
a transfer outlet pipe inserted into the filling space of the second underground heat exchange system to supply groundwater sucked by the transfer inlet pipe; and
and a fourth pump disposed between the transfer inlet pipe and the transfer outlet pipe to transport groundwater. 10. The method of claim 9,
The transfer and withdrawal pipe is formed to extend to the lower end of the filling space of the second underground heat exchange system. 10. The method of claim 9,
The double tube type underground heat exchange system further comprising a second heat exchanger performing heat exchange from the groundwater transferred by the groundwater transfer unit.

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