JP2005326128A - Heat exchanger using ground heat and air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger using ground heat, capable of efficiently extracting ground heat, and an air conditioner using it. <P>SOLUTION: In this heat exchanger using ground heat, air is distributed in an outer cylindrical tube 20 buried in a ground 14, whereby heat exchange is performed between the heat of the air and the ground heat. A film 22 containing a minute carbon material such as carbon nanotube is formed in at least a part of the inner wall surface of the outer cylindrical tube 20. An inner cylindrical tube 30 is inserted into the outer cylindrical tube 20. According to this, the heat exchange can be efficiently performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat exchanger and an air conditioner using geothermal heat. More specifically, a heat exchanger that uses geothermal heat to exchange heat between the heat existing in the fluid and the geothermal heat by circulating the fluid inside the cylinder embedded in the ground, and using the heat exchanger It relates to the air conditioning apparatus.

Technology development to reduce energy consumption is an important theme. One solution is to use geothermal heat. In the ground above a predetermined depth, the ground temperature is a constant temperature around 15 ° C throughout the year. In addition, the underground volume is enormous, and the earth and sand are extremely large heat storage tanks.
By using a natural heat source having a constant temperature and a large capacity, it is possible to reduce energy consumption in cooling in the summer and heating in the winter.

Conventionally, as a method of using geothermal heat, there are a method of providing a pipeline that circulates between the underground and the room, and a method of circulating groundwater and a method of circulating air. In these methods, a fluid is used as a heat medium.
A method of using air as a heat medium after using groundwater has also been proposed. (See Patent Document 1).
JP-A-5-223356 (first page)

The problem to be solved with respect to a heat exchanger that uses geothermal heat is that, particularly when air is used as a heat medium, it is difficult to efficiently extract geothermal heat because the thermal conductivity of air is low. As a result, in order to obtain a predetermined amount of heat, the apparatus has become large or complicated.
Then, the objective of this invention is providing the heat exchanger using the geothermal which can take out geothermal efficiently, and the air conditioning apparatus using the same.

The present invention has the following configuration in order to achieve the above object.
According to one aspect of the heat exchanger using geothermal heat according to the present invention, heat is exchanged between the heat existing in the fluid and the geothermal heat by circulating the fluid through the cylindrical body embedded in the ground. In the heat exchanger using geothermal heat, a coating containing a fine carbon material such as carbon nanotube is formed on at least a part of the inner wall surface of the cylindrical body.

  Further, according to one aspect of the heat exchanger using geothermal heat according to the present invention, the cylindrical body is provided as an outer cylindrical tube standing substantially vertically in the ground, and the inner cylindrical tube includes the outer cylindrical tube. An inner tube for flowing fluid between the lower part in the tube and the ground surface is inserted.

Moreover, according to one form of the heat exchanger using the geothermal heat concerning this invention, the said outer cylinder pipe is provided with the metal material, The said inner cylinder pipe is provided with the resin material, It is characterized by the above-mentioned. it can.
According to one aspect of the heat exchanger using geothermal heat according to the present invention, the fluid is air, and the air is passed between the inner wall surface of the outer tube and the outer wall surface of the inner tube, It can be characterized by comprising air blowing means that circulates inside the tube.

  Moreover, according to one form of the air-conditioning apparatus concerning this invention, it can cool or heat by introducing geothermal heat into a room | chamber interior using the heat exchanger using said geothermal heat.

According to the heat exchanger using the geothermal heat of the present invention, heat radiation or heat absorption is made extremely efficiently by the coating containing a fine carbon material such as carbon nanotubes formed on the inner wall surface of the cylindrical body. Efficiency can be improved dramatically.
Therefore, it becomes possible to cool or heat the room suitably using geothermal heat. The apparatus can be provided inexpensively and suitably without increasing its size and complexity.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of the best mode of a heat exchanger and a cooling / heating device using geothermal heat according to the present invention will be described in detail with reference to the accompanying drawings (FIG. 1). FIG. 1 is a cross-sectional view schematically showing a heat exchanger 10 and an air conditioner 12 using geothermal heat according to the invention.
A heat exchanger 10 circulates fluid through a cylinder (outer tube 20) embedded in the underground 14 to exchange heat between the heat existing in the fluid and the geothermal heat. In FIG. 1, the form which distribute | circulates air is shown.

Reference numeral 22 denotes a coating containing a fine carbon material such as a carbon nanotube (hereinafter also simply referred to as “coating 22”), and is formed on at least a part of the inner wall surface of the outer tube 20. In the present embodiment, the coating 22 is formed on the entire inner wall surface. An inner bottom surface 25 is also formed.
Since the coating 22 has high thermal conductivity and heat dissipation, it is effective even if it is formed in a part. In a deep part of the underground corresponding to the position of the lower part of the outer tube 20, the ground temperature is constant throughout the year when it reaches a predetermined depth. In the present invention, the purpose is to use the geothermal heat of that layer, and when the coating 22 is formed in part, it is a matter of course that the lower inner wall surface of the outer tube 20 is given priority.
Further, if the coating 22 is formed on the entire surface, the heat in the lower part of the outer tube 20 can be suitably conducted to the upper part due to high thermal conductivity, and heat exchange with a substantially large surface area becomes possible. In order to utilize this conduction heat transfer suitably, the film 22 should be thick. However, fine carbon materials such as carbon nanotubes are expensive, and there is a limit to the heat dissipation performance depending on the surface area. Therefore, it is possible to set the optimum thickness of the coating film 22 in relation to the thermal conductivity and the heat dissipation.

  Here, the fine carbon material such as carbon nanotube is a single-walled carbon nanotube, a multi-walled carbon nanotube, an end fiber, a carbon nanohorn, a carbon microcoil, a fullerene and the like in addition to “carbon nanotube” as a generic name. This fine carbon material can be said to be a crystalline carbon material, and is sometimes called a nanocarbon material. These are materials that can be produced by nanotechnology as fine materials with excellent physical properties such as extremely high thermal conductivity. At the present time, carbon nanotubes can be suitably used from the viewpoints of performance and cost.

Moreover, a coating film is a coating layer formed on the surface of a material, for example, a coating film formed by applying a paint. The coating film 22 according to the present invention can be formed by appropriately mixing and dispersing carbon nanotubes in a well-known paint and applying it to the surface of a metal material. Thereby, the layer by a carbon nanotube can be uniformly formed in the surface of a metal material. The fine carbon material such as carbon nanotubes preferably acts as a functional additive for the paint forming the coating 22.
When heat resistance, chemical resistance, etc. are required for the paint, a well-known paint having a function corresponding thereto, such as one using an organic solvent, or a silicone rubber (silicone resin) -based coating material is used. Can be used. Some of these coating materials may be dried at room temperature, or may be appropriately applied with known techniques such as baking to improve the adhesion and hardness of the coating.

Further, the mixing ratio of the carbon nanotubes to the coating is considered to improve the performance as the amount of carbon nanotubes increases, but may be set as appropriate in consideration of the dispersibility and the like.
In addition, when an experiment was performed by applying a paint in which carbon nanotubes were mixed at a weight ratio of 10%, an extremely high heat radiation performance (cooling performance) could be obtained.
This is thought to be due to the extremely high thermal radiation of the carbon nanotubes. The phenomenon of heat emission is considered to be the dissipation of waves (a kind of electromagnetic wave) because heat is also a kind of wave. That is, it is radiation of various wavelengths, and it is considered that the carbon nanotubes do not need to be exposed or overlapped with a certain thickness. Any carbon nanotube may be used as long as the surface is uniformly coated. This is because the injection amount depends on the surface area. In addition, even in the form existing in the paint, it is considered that the element that prevents the wave emission is small. Note that it is considered suitable to use a highly transparent paint.
Similarly, carbon nanotubes have high endothermic performance.

Reference numeral 20 denotes an outer cylindrical tube, which is provided as a cylindrical body standing substantially vertically in the ground.
The outer tube 20 is made of a metal material. Here, the metal material is not particularly limited as long as it is a material having a higher thermal conductivity than other materials such as a resin material and has a certain strength as a structural material. For example, an aluminum material, a stainless steel material, a copper material, a steel material, or the like may be selectively used as appropriate. A copper material is good in consideration of heat conduction performance, but a stainless steel material may be adopted in consideration of corrosion resistance.

The outer tube 20 of this embodiment is a metal pipe and can secure a suitable strength that can withstand earth pressure. Moreover, the heat conduction performance is higher than earth and sand, and geothermal heat can be taken out suitably.
In this embodiment, the bottom of the outer tube 20 is closed by the bottom plate 21. This is to prevent inflow of groundwater. Note that it is not necessary to close the bottom of the outer tube 20 depending on the conditions of the installation place or the application.

Reference numeral 30 denotes an inner tube, which is inserted into the outer tube 20. The inner tube 30 is made of a resin material. According to the inner tube 30, it is possible to suitably distribute the fluid between the lower part 24 in the outer tube 20 and the ground surface 16.
As shown in FIG. 1, it has a double tube structure of an outer tube 20 and an inner tube 30. In addition, the inner tube 30 is appropriately fixed by a support material (not shown) so that the lower end 31 thereof is positioned at a predetermined distance from the lower end (inner bottom surface 25) of the outer tube 20.
Thereby, a predetermined space (first flow path 40) serving as a flow path for fluid (in this embodiment, air) can be obtained between the inner wall surface of the outer tube 20 and the outer wall surface of the inner tube 30. Further, the inner space 26 at the lower end portion of the outer tube 20 becomes an air flow reversal space. The inner space of the inner tube 30 is an air flow path (second flow path 42).

  The inner tube 30 in this embodiment is a resin pipe and is formed of a material having low heat conduction performance. For example, a vinyl chloride tube can be used. In this way, by using a pipe having a low thermal conductivity, a fluid (air) that is suitably heat-exchanged at a deep position in the ground can be suitably circulated. This is because it is possible to prevent the heat once exchanged by heat and absorbed in the air (including the negative heat when cooled) from being emitted.

  Reference numeral 50 denotes air blowing means, which is connected to the inner tube 30. (Note that the shape and the like of the piping can be designed as appropriate, and details are not shown.) For example, an axial fan can be used. According to this blower means 50, air is circulated between the inner wall surface of the outer tube and the outer wall surface of the inner tube (first flow path 40) and inside the inner tube (second flow path 42). Can be made. FIG. 1 shows a state in which air passes through the first flow path 40 and the second flow path 42 from the indoor 60 side as indicated by arrows. In this case, the blower 50 blows air so as to suck air.

Thus, the air blown by the blowing means 50 may be opened to the room 60, or may be circulated through a path (pipe 72) indicated by a two-dot chain line. Reference numeral 70 denotes a heat exchange unit on the ground, which can be, for example, a wine cellar, a storage (cold storage, heat storage), a cooling unit, a heat dissipation unit, or the like.
Thus, if the heat exchanger 10 demonstrated above is used, the air conditioning apparatus 12 which cools or heats by introducing geothermal heat indoors can be comprised suitably.
When the heat-exchanged air is directly introduced into the room 60, there is little heat loss and the room 60 can be efficiently air-conditioned. Since a natural energy source called geothermal is used, energy for operating the blower is required, but the energy cost can be greatly reduced. Since air can be used as a heat medium, there is an advantage that it is easy to handle, safe, stable, and inexpensive.

Reference numeral 51 denotes another air blowing means, which can obtain an air flow similar to the above by pushing air. (Note that the shape and the like of the piping can be designed as appropriate, and details are not shown.) In this embodiment, the first flow path 40 is an air supply flow path, and the second flow path 42 is an exhaust pipe path. ing. Note that if air is blown through the filter, the inner wall surface of the outer tube 20 is not soiled, and a suitable heat exchange performance can be maintained.
Moreover, it is possible to obtain suitable heat exchange performance even when the air blowing direction is opposite to the direction of the arrow shown in FIG.
The heat of the air subjected to heat exchange may be stored in a heat storage tank, or may be used for indoor air conditioning or water temperature adjustment through a heat exchanger installed indoors.
Moreover, if the heat exchanger 10 demonstrated above is reversely utilized and the solar energy collected on the roof and the wall surface is sent in the ground, it can be suitably stored in the earth and sand. In winter, heat can be stored during the day and used as nighttime heating.

Reference numeral 80 denotes a heat insulating member, which is provided to reduce the thermal influence from the earth and sand near the ground surface. In this form, it is provided so that the outer peripheral surface of the upper part of the outer cylinder pipe 20 may be surrounded. For example, as shown in FIG. 1, the resin tube can be provided in a state of being fitted to the upper outer side of the outer tube 20. As the resin tube, for example, a vinyl chloride tube can be used.
According to this, it is possible to prevent the heat conducted and transferred from the deep underground by the coating 22 and the metal tube (the outer tube 20) from being dissipated to the earth and sand in the layer close to the ground surface. Therefore, heat can be exchanged efficiently.

A heat exchanger radiator using geothermal heat according to the present invention will be described with reference to Example 1 (FIG. 2). FIG. 2 is a cross-sectional view schematically showing the heat exchanger 10 using geothermal heat according to the invention.
Reference numeral 90 denotes a fin, which is formed on the outer wall surface of the inner tube 30 (shown on the left side in FIG. 2). It is formed so as to protrude toward the outside of the inner tube 30. According to the fin 90, it is possible to suitably disturb the flowing air flow. Thereby, heat transfer by turbulent flow is performed, and the heat exchange efficiency is improved. The shape of the fin 90 can be a blade shape inclined so as to generate a spiral swirl flow or a spiral flow in order to reduce the airflow resistance. In addition, since it is an outer wall surface, there also exists an advantage which is easy to form the fin 90. FIG.

Further, the fin 90 may be formed on the inner wall surface of the outer tube 20 (shown on the right side in FIG. 2). It is formed so as to protrude into the outer tube 20. According to this, since the surface area of the heat radiating surface or the heat absorbing surface for heat exchange can be increased, the heat exchange performance can be improved.
Note that only the fin 90 may be separately formed and inserted between the inner wall surface of the outer tube 20 and the outer wall surface of the inner tube 30. In this case, the separate fin 90 may be formed of a metal material, the coating 22 may be provided on the surface thereof, and the coating may be brought into contact with the coating 22 on the inner wall surface of the outer tube 20. The surface area for heat exchange can be substantially expanded and the heat exchange performance can be improved.
In any form, the fin 90 can also function as a spacer for suitably providing the first flow path 40.

Reference numeral 92 denotes a pump, which can be used to discharge water accumulated in the outer tube 20 due to condensation or the like. It is only necessary to install a sensor so that it operates only when a predetermined amount of water has accumulated.
Reference numeral 94 denotes a humidity control agent, which is deposited on the bottom of the outer tube 20. The humidity can be adjusted, for example, by removing moisture that rises when the air is cooled.

In order to embed the outer tube 20 in the ground, a well-known boring technique or a technique for driving a pile into the ground may be used. When the construction method of driving the outer tube 20 into the ground is used, the lower end 28 of the outer tube 20 can be sharpened as shown in FIG.
In the present invention, the portions disposed in the ground of the outer tube 20 and the inner tube 30 are straight tubes (straight tubes), and can be installed relatively easily and inexpensively. Further, there is an advantage that it can be manufactured relatively easily and inexpensively.
In order to improve the efficiency of conduction heat transfer between the outer tube 20 and the earth and sand 18, the outer wall surface of the outer tube 20 and the earth and sand 18 may be brought into close contact with each other. An adhesive material such as bentonite may be inserted and interposed.

  As described above, the present invention has been described in various ways with reference to preferred embodiments. However, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. That is.

INDUSTRIAL APPLICABILITY The present invention can be used for indoor air conditioning of a highly airtight and highly insulated house, an air circulation type house, and other buildings. In either case, the heat-exchanged air can be directly introduced into the room.
It is also possible to circulate a fluid such as air or water as a heat medium and perform air conditioning through a heat exchanger provided in the room.
Further, the method of circulating the heat-exchanged air includes circulating the inside of the building or the back of the ceiling. According to this, the air conditioning by another apparatus can be assisted suitably.
Moreover, it can utilize suitably also for the agricultural facilities which require temperature control, such as the greenhouse for promotion cultivation, a greenhouse, and the facility for mushroom cultivation.
Furthermore, it can be suitably used in other applications that require energy saving.

It is sectional drawing which shows the heat exchanger and air-conditioning apparatus using the geothermal heat of one form of this invention. It is sectional drawing which shows Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Heat exchanger 12 Air-conditioning / heating apparatus 14 Underground 20 Outer cylinder pipe 22 Coating 30 Inner cylinder pipe 40 1st flow path 42 2nd flow path 50 Blowing means 60 Indoor 80 Heat insulation member 90 Fin

Claims (5)

In a heat exchanger that uses geothermal heat to exchange heat between the heat existing in the fluid and the geothermal heat by circulating the fluid inside the cylinder embedded in the ground,
A heat exchanger using geothermal heat, wherein a coating containing a fine carbon material such as a carbon nanotube is formed on at least a part of the inner wall surface of the cylindrical body.   The cylindrical body is provided as an outer cylindrical pipe standing substantially vertically in the ground, and an inner cylindrical pipe for allowing fluid to flow between the lower portion of the pipe and the ground surface is provided inside the outer cylindrical pipe. The heat exchanger using geothermal heat according to claim 1, wherein the heat exchanger is inserted.   The heat exchanger using geothermal heat according to claim 2, wherein the outer tube is made of a metal material, and the inner tube is made of a resin material.   3. The air according to claim 2, further comprising air blowing means for circulating the air between the inner wall surface of the outer tube and the outer wall surface of the inner tube, and inside the inner tube. Or a heat exchanger using the geothermal heat described in 3.   An air-conditioning apparatus that performs cooling or heating by introducing geothermal heat into a room using a heat exchanger that uses geothermal heat according to claim 1.

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