JP2015190715A - Geothermal heat exchanger body, geothermal heat exchanger, geothermal heat exchanging system and construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a geothermal heat exchanger et al. that can be efficiently laid in a small space.SOLUTION: A body 1 is used for a heat exchanger to perform heat exchange between a liquid medium circulated in the inside of a pipe body embedded in the ground and the ground. The body includes a stainless pipe 11 with an outer diameter of 15 mm or more and 25 mm or less, and a tip bit 12 connected to the side of one end 111 of the pipe 11 and including a tip part 121 forming a polyhedral cone shape disposed to one end while turning a bottom face 122. One end 111 of the pipe 11 is closed liquid-tightly by a tip bit 12 or by a connecting component 13 interposed between the pipe 11 and the tip bit 12. The bottom face 122 of the tip bit 12 is made the same as an outer circumference of the one end 111 of the pipe 11 or is made larger than that, and the polyhedral cone shape has side faces 123 of three faces or more and eight faces or less. The method includes a first step of applying a load to the body 1 by punching pressure or pressing force, and a second step of rotating the body 1.

Description

  The present invention relates to an underground heat exchanger main body, an underground heat exchanger, an underground heat exchange system, and a construction method. More specifically, the present invention relates to an underground heat exchanger main body, an underground heat exchanger, an underground heat exchange system, and a construction method that can be efficiently laid in a small space.

  In recent years, from the viewpoint of reducing the use of fossil fuels, the effective use of renewable energy such as sunlight, wind power, geothermal heat, wave power, and biomass has attracted attention. Among them, as a technique for using geothermal heat, a technique for underground heat exchange using constant geothermal heat is known. While the temperature on the ground (atmospheric temperature) varies greatly depending on the season, the temperature in the ground is hardly affected by this. Temperature. This can be understood from the fact that the well water feels cold in the summer and warm in the winter, and that the temperature in the cave remains low even under high outdoor temperatures in the summer.

Currently, an air conditioner that is generally used is a kind of atmospheric heat source heat pump. That is, it is a heat pump that uses air as a heat source for exchanging heat energy between the room and the outdoors (atmosphere) via an outdoor unit installed outdoors.
However, in such an atmospheric heat source heat pump, it is necessary to radiate the heat energy taken indoors in the summer to the high temperature atmosphere and collect the heat energy from the low temperature outdoor in the winter. Further, for example, the atmospheric heat source heat pump has a problem that the thermal energy efficiency is low, such as performing a defrosting operation in order to prevent the outdoor unit from freezing in winter. In addition, even in heat pump water heaters that have become popular for all-electric homes in recent years, the atmospheric heat source heat pump system is the mainstream, and heat energy is collected from outdoor cold air in winter, especially in winter, energy efficiency decreases. Have similar problems.
As described above, the atmospheric heat source heat pump has a problem that the energy efficiency is lowered due to the influence of the heat source on the season and the weather. In contrast, the underground heat source heat pump is not affected by the season or weather, and is maintained at a temperature of about + 5 ° C to 5 ° C with respect to the annual average temperature. Therefore, it has higher energy efficiency than the atmospheric heat source heat pump. It is expected and preferable from the viewpoint of promoting energy saving and suppressing CO ₂ emission.

However, the underground (such as earth and sand) that is the heat source of the underground heat source heat pump is inferior in thermal conductivity to the atmosphere (air) that is the heat source of the atmospheric heat source heat pump. Therefore, even a general household facility usually requires a heat exchanger with a total length of about 100 m for heat exchange. And the underground heat exchanger currently utilized is a form (refer nonpatent literature 1) called a borehole + U-shaped tube system etc.
In this mode (see FIG. 8), first, a borehole 90 having a diameter of 100 mm or more and a depth of about 100 m is excavated using a dedicated excavation heavy machine. At that time, an iron pipe called a casing 92 is buried in the ground so that the earth wall 91 in the bore hole 90 does not collapse. Also, the earth and sand in the borehole 90 to be dug is discharged as sludge to the ground using water 93. When the borehole 90 is excavated to a predetermined depth, a resin U-tube tube 94 for circulating a heat medium is inserted into the borehole 90. Thereafter, the inside of the bore hole 90 is backfilled with sand 95 so that the U-shaped tube tube 94 is embedded in the bore hole 90, and finally, the casing 92 is extracted from the ground, whereby a borehole + U-shaped tube type underground heat exchanger is obtained. Is completed. As described above, the borehole + U-shaped underground heat exchanger requires large heavy machinery and sludge treatment equipment for installation, and costs and a large site are required for the installation.

For this reason, the geothermal heat source heat pump has a problem that even if it is adopted in a large-scale facility such as an office building, a commercial facility, or a school facility, it is difficult to adopt it in a facility smaller than a general house. That is, the underground heat source heat pump having the conventional configuration requires a large-scale laying work, and there is a problem that it is difficult to retrofit to an existing building due to its scale. It is a hindrance to the spread.
In order to solve such a problem, techniques of Patent Document 1 and Patent Document 2 below are known.

JP 2004-233031 A JP 2003-014385 A "Introduction example of heat pump air conditioning system using geothermal heat" (heat pump and its application 81, geothermal heat utilization), [online], Chugoku Electric Power Co., Inc., [March 19, 2014 search], Internet <URL: http : //enec-n.energia.co.jp/enec_data/chikunetsu/heatpump/hp81/hp81-06.pdf>

In the above-mentioned Patent Document 1, a hollow tube having a rotating blade attached to the lower end is rotationally press-fitted with a rotational force and a downward force, and is constructed using the internal space of the embedded hollow tube. An underground heat exchanger is disclosed.
According to this technology, the hollow tube that has been press-fitted underground is used as a foundation pile to support the building and also as a heat exchanger, so compared to the case where these are installed separately, The introduction cost of the heat source heat pump can be suppressed.
However, in general houses, solid foundations or cloth foundations are usually adopted, and the percentage of houses where foundation piles are installed is low. For this reason, the technology disclosed in Patent Document 1 can be used in large-scale facilities as in the case of the borehole method, and is difficult to be used in small-scale ordinary houses. Furthermore, the foundation pile is installed before building the building, and this heat exchanger cannot be retrofitted to the existing foundation pile. Moreover, since the hollow tube body in Patent Document 1 has rotating blades, a large reaction force is generated at the time of press-fitting into the ground, and a large heavy machine is required for the press-fitting.
In other words, compared to the borehole method, installation costs can be reduced for buildings with foundation piles, but they are difficult to adopt for smaller facilities such as ordinary houses, and are difficult to retrofit. It has the same problems as the borehole method in terms of the points.

In Patent Document 2, heat is transferred between the ground and the load to be used via a heat medium that is buried in the ground and passes through the peripheral wall of the bottomed straight pipe. An underground heat exchanger using an underground heat collection pipe is disclosed. In addition, this underground heat sampling pipe has a drilling blade at the outer low part and can be rotary press-fitted into the ground, thereby preventing noise, vibration, and exhaust without disturbing the surrounding soil in a short time. It can be installed without soil.
However, the straight pipe of Patent Document 2 has a digging blade at its tip. When trying to rotationally press a straight pipe using a drilling blade into the ground, the straight pipe receives a large reaction force generated by the drilling blade. Moreover, as described above, the underground heat is generally constant at a depth of 5 m or more, and therefore the underground heat exchanger needs to be buried to a depth of 5 m or more. Therefore, as the straight pipe is inserted into the ground, the excavating blade and the force point that gives the rotational force (the end on the ground side of the straight pipe) are separated by 5 m or more, and the strong point applied to the ground side end of the straight pipe Due to the rotational force, the straight pipe will “bend”, fail to dig, and eventually break.
After all, a sufficiently thick pipe wall and a large pipe diameter are indispensable for a straight pipe using an excavating blade to withstand rotational press-fitting. And, as the diameter increases, the number of soil removal increases, and when the amount of soil removal exceeds a certain level, a soil removal treatment using water is eventually required as in the case of borehole excavation. Furthermore, a heavy machine is required to advance the pipe against a large reaction force caused by the digging blade. Patent Document 2 does not recognize any problems that occur during actual laying, and does not examine the problems.

  The present invention has been made in view of the above prior art, and provides a main body for a ground heat exchanger, a ground heat exchanger, a ground heat exchange system, and a construction method that can be efficiently laid in a small space. Objective.

That is, the present invention is as follows.
The main body for an underground heat exchanger according to claim 1 is used for an underground heat exchanger that performs heat exchange between a liquid medium that is circulated inside a tubular body embedded in the underground and the underground. Is a main body for underground heat exchanger,
A stainless steel tube having an outer diameter of 15 mm to 25 mm;
A tip bit that is connected to one end side of the stainless steel pipe and has a tip portion having a polyhedral conical shape disposed with the bottom face facing the one end;
The one end of the stainless steel pipe is liquid-tightly closed by the tip bit or by a connecting part interposed between the stainless steel pipe and the tip bit,
The bottom surface of the tip bit is the same as or larger than the outer periphery of the one end of the stainless steel tube,
The gist of the present invention is that the polyhedral pyramid has three or more and eight or less side surfaces.
The main body for an underground heat exchanger according to claim 2 is the main body for an underground heat exchanger according to claim 1, wherein a central axis of the tip bit and a tip portion forming the polyhedral cone shape constituting the tip bit. The gist is that the angle with the side surface is 15 degrees or more and 40 degrees or less.
Underground heat exchanger body as claimed in claim 3 is the underground heat exchanger body as claimed in claim 1 or 2, the outer diameter of the stainless steel tube and D _O, the inside diameter of the stainless steel tube and D _I when the ratio _D O / _{D I} between the outer diameter and inner diameter, and summarized in that is 1.2 to 2.0.
The main body for an underground heat exchanger according to claim 4 is the main body for an underground heat exchanger according to any one of claims 1 to 3, wherein the stainless steel tube is connected to a plurality of individual stainless steel tubes. This is the gist.
The main body for underground heat exchanger according to claim 5 is the main body for underground heat exchanger according to any one of claims 1 to 4, wherein the stainless steel tube has a length of 5 m or more and 15 m or less. Is the gist.
The underground heat exchanger according to claim 6, a main body for the underground heat exchanger according to any one of claims 1 to 5,
A resin tube inserted into the stainless steel tube,
The gist is that a gap formed between the resin pipe and the stainless steel pipe is used as a flow path of the liquid medium.
The underground heat exchange system according to claim 7, the underground heat exchanger according to claim 6,
And a liquid medium distribution means for distributing the liquid medium in the underground heat exchanger.
The ground heat exchanging system according to claim 8 is the ground heat exchanging system according to claim 7, characterized in that it comprises two or more of the underground heat exchangers.
The underground heat exchange system according to claim 9 is the underground heat exchange system according to claim 7 or 8, wherein the underground heat exchanger is connected in parallel to the flow path of the liquid medium. This is the gist.
The underground heat exchange system according to claim 10 is the underground heat exchange system according to any one of claims 7 to 9, wherein the liquid medium has a volume of 50 vol. The gist is to contain at least% water.
The construction method of the underground heat exchange system according to claim 11 is the construction method of the underground heat exchange system according to any one of claims 7 to 10, wherein the main body for the underground heat exchanger is a ground surface. The tip of the tip bit is erected on the ground so as to be substantially vertical to the tip of the underground heat exchanger by pressing or pressing from the rear end side toward the tip bit side. A first step of applying a load to the
A second step of rotating the underground heat exchanger main body so that the tip bit is rotated in the ground,
The gist is to perform the first step and the second step simultaneously or alternately.

According to the underground heat exchanger main body of the present invention, the underground heat exchanger main body can be embedded in the ground efficiently and in a small space. That is, the underground heat exchanger main body of the present invention can be employed in a small general house. Also, it can be laid regardless of the building construction. Furthermore, it can be laid without requiring heavy equipment and does not require sludge treatment.
These effects are obtained due to the configuration of the present invention. That is, the underground heat exchanger main body of the present invention has a multi-sided cone-shaped tip bit, but does not have a portion that generates a large reaction force such as a rotary blade or a drilling blade. Therefore, the earth and sand to which the main body for the underground heat exchanger is inserted is pushed away, and it can be inserted into the ground while being compressed and pushed around the tip bit, so that the sludge treatment due to the soil removal is not required. Moreover, when it has a rotary blade | wing, earth and sand enter between blades, the earth and sand become resistance, and insertion to a certain depth or more becomes difficult. However, since the main body for an underground heat exchanger does not have a rotating blade or the like, the entry of such earth and sand does not occur, and the resistance accompanying the entry of earth and sand does not occur.
Furthermore, the outer diameter of the tube is 15 mm or more and 25 mm or less, which is very small compared to the diameter of the bore hole 90 shown in FIG. The load is small. Therefore, the pipe can be easily buried in the ground without using heavy equipment. Moreover, since it is not necessary to use heavy machinery, the land area required for laying can be remarkably reduced as compared with the conventional case. Since the land area is small, it can be used in small ordinary houses and can be laid regardless of the construction of the building. That is, the underground heat exchanger can be retrofitted.
Moreover, since the outer diameter of the pipe is 15 mm or more and 25 mm or less, when the underground heat exchanger main body is inserted into the ground, the volume of earth and sand that the pipe is pushed away to the surroundings is small. Therefore, the amount of earth and sand that the pipe is pushed away at the time of insertion is small, and the earth and sand around the inserted pipe can be kept to an amount that can absorb these unnecessary earth and sand. That is, it can be inserted while compressing and pushing unnecessary earth and sand around the pipe at the time of insertion. Therefore, no soil discharge occurs and there is no need to perform a soil removal process.
Also, as a result, the earth heat exchanger body is inserted into the ground by pushing away the soil around the pipe, so that the filling rate of the earth and sand around the pipe increases, while the amount of air in the earth and sand around the pipe increases. Therefore, the thermal conductivity of the earth and sand around the pipe can be improved.

When the angle between the central axis of the tip bit and the side surface of the tip portion forming the polyhedral cone forming the tip bit is 15 degrees or more and 40 degrees or less, the underground heat exchanger main body is inserted into the ground. Can be easily.
The ratio D _{O /} D _I between the outer diameter and the inner diameter of the stainless steel tube, when it is 1.2 or more and 2.0 or less, and more effectively suppress the bending of the underground heat exchanger body Since the load necessary for insertion into the underground can be efficiently applied to the main body for the underground heat exchanger, embedding can be performed more easily.
When multiple stainless steel pipes are connected to the stainless steel pipe, it is recommended to connect the pipes little by little while the insertion into the ground is progressing. The length of the stainless steel pipe can always be kept short, and the work efficiency is excellent.
When the length of the stainless steel pipe constituting the main body for underground heat exchanger is 5m or more and 15m or less, the pipe with a sufficiently small force compared to the case where a pipe with a length exceeding this range is inserted into the soil Can be buried.

Both the underground heat exchanger of the present invention and the underground heat exchange system of the present invention can be efficiently laid in a small space.
Moreover, in the underground heat exchange system provided with two or more said underground heat exchangers, since the whole length of the part which can be heat-exchanged can be adjusted according to a request | requirement, optimal heat exchange capability can be obtained.
In the underground heat exchange system in which the underground heat exchanger is connected in parallel to the flow path of the liquid medium, it is possible to secure a longer heat exchange distance while reducing the load on the liquid medium circulation means. .
According to the construction method of the underground heat exchange system of the present invention, the underground heat exchange system can be constructed efficiently in a small space.

It is explanatory drawing which shows an example of the main body for underground heat exchangers of this invention. It is explanatory drawing which shows the other examples of the main body for underground heat exchangers of this invention. It is explanatory drawing which shows an example of the front-end | tip bit used for this invention. It is explanatory drawing which shows the other example of the front-end | tip bit used for this invention. It is explanatory drawing explaining the embedding process of the main body for underground heat exchangers of this invention. It is explanatory drawing which shows an example of the underground heat exchanger of this invention. It is explanatory drawing explaining the underground heat exchanger system of this invention. It is explanatory drawing explaining the embedding process of the conventional underground heat exchanger.

The present invention will be described in detail below.
[1] Main body for underground heat exchanger The main body for underground heat exchanger (1) of the present invention (see FIGS. 1-4) includes a liquid medium that circulates inside a tubular body embedded in the ground, , A main body for an underground heat exchanger (1) used for an underground heat exchanger that performs heat exchange between
A stainless pipe (11) having an outer diameter of 15 mm or more and 25 mm or less;
A tip bit (12) provided with a tip portion (121) having a polyhedral cone shape connected to one end side (111) of the stainless steel pipe (11) and facing the bottom surface (122) toward the one end (111). ) And
One end (111) of the stainless steel pipe (11) is liquid-tightly closed by a tip bit (12) or by a connecting part (13) interposed between the stainless steel pipe (11) and the tip bit (12). Has been
The bottom surface (122) of the tip bit (12) is the same as or larger than the outer periphery of one end (111) of the stainless steel tube (11),
The polyhedral cone has three or more and eight or less side surfaces (123).

The main body for an underground heat exchanger according to the present invention includes a tip bit 12, and the tip bit 12 has a tip 121 having a polyhedral cone shape.
Further, this polyhedral conical shape has side surfaces 123 of 3 or more and 8 or less. That is, the polyhedral pyramid shape is any one of a triangular pyramid shape, a quadrangular pyramid shape, a pentagonal pyramid shape, a hexagonal pyramid shape, a heptagonal pyramid shape, and an octagonal pyramid shape. A polygonal pyramid shape exceeding eight surfaces is not preferable because it gradually approaches a conical shape and tends to reduce the effect of pushing away soil in the direction of digging by rotation to the surroundings.
The polygonal pyramid shape may be 3 or more and 8 or less, and among them, a triangular pyramid shape, a quadrangular pyramid shape, a pentagonal pyramid shape and a hexagonal pyramid shape are preferable, and in particular, a triangular pyramid shape or a quadrangular pyramid shape Shape is preferred.

Further, the triangular pyramid shape and the quadrangular pyramid shape are preferably a quadrangular pyramid shape. This is because the component angle of the ridge line constituting the polyhedral pyramid shape (the component angle of 60 degrees for the triangular pyramid and the component angle of 90 degrees for the quadrangular pyramid) can be increased, so that the strength at the ridge line 124 of the tip bit can be increased. It is.
In particular, when the cross-sectional shape of the stainless steel tube 11 is circular, the tip portion of the tip bit is a quadrangular pyramid shape rather than a triangular pyramid shape. Can be covered. That is, if an end portion that is the same as or larger than the outer periphery of the one end 111 of the circular stainless steel tube 11 is to be secured by a triangular pyramid shape, the ridge line overhangs. On the other hand, if it tries to secure by a quadrangular pyramid shape, the overhang of a ridgeline can be made smaller.

Furthermore, the angle θ (see FIGS. 3 and 4) between the central axis 12A of the tip bit 12 and the side surface 123 of the tip portion 121 that forms the polyhedral cone shape that constitutes the tip bit 12 is not particularly limited. It is preferably 15 degrees or more and 40 degrees or less. In the range of 15 degrees or more and 40 degrees or less, an angle that can withstand the load applied to the tip portion by the striking pressure or pressing can be secured, and the load by the striking pressure or pressing can be efficiently concentrated on the tip without escaping to the side. be able to. This angle is more preferably 18 degrees or more and 35 degrees or less.
In addition, as for the angle of the center axis | shaft and side surface of a front-end | tip bit, all the side surfaces may have the same angle and the side surface of 2 or more types of different angles may be contained. Even in such a case, it is preferable that all surfaces are included in the above-described preferable range.

  Further, the shape of the bottom surface of the tip bit 12 is not particularly limited. For example, when the tip portion 121 has a quadrangular pyramid shape, it may be circular as shown in FIG. 3 or square as shown in FIG. can do. Among these, when the cross-sectional shape of the stainless steel tube 11 is circular, it is preferable that the bottom surface shape is a similar circular shape (see FIG. 3). When the cross-sectional shape of the stainless steel tube 11 is circular, the bottom surface shape can cover the one end side of the stainless steel tube 11 with a smaller area than the rectangular shape.

Further, the bottom surface 122 of the tip bit 12 is the same as or larger than the outer periphery of the one end 111 of the stainless steel tube 11. That is, one end 111 of the stainless steel tube 11 is covered by the tip bit 12. With this configuration, the tip bit 12 pushes away the soil that becomes resistance when the stainless steel tube 11 is subsequently inserted, so the main body 1 for the underground heat exchanger of the present invention is inserted into the ground. It is possible to further reduce the resistance when performing.
When the bottom surface 122 of the tip bit 12 is larger than the outer periphery of the one end 111 of the stainless tube 11, the protrusion of the bottom surface 122 of the tip bit from the outer peripheral surface of the stainless tube 11 is preferably 10 mm or less, and 5 mm or less. More preferred is 2 mm or less.

  Furthermore, although the material which comprises the front-end | tip bit 12 is not specifically limited, Usually, it is a metal or ceramics. Of these, metals are preferred from the viewpoint of formability. The hardness of the tip bit 12 (according to JIS Z2244 (2009)) is preferably high, and is preferably 500 HV or higher (usually 950 HV or lower). The hardness is more preferably 600 HV or more, further preferably 700 HV or more, and particularly preferably 750 HV or more. Specifically, such a material is a steel material having a martensite structure, and examples thereof include SUJ2, SUS440C, and SK140 that have been quenched and tempered.

In the underground heat exchanger main body 1 of the present invention, the fact that the tip 121 is a multi-faced cone shape is considered to be a major factor that allows the underground heat exchanger main body 1 to be embedded in the ground efficiently in a small space. It is done. That is, the force from the rear end side 112 of the underground heat exchanger main body 1 can be concentratedly applied to the front end side (one end side 111), and the earth and sand around the front end 121 can be moved to the side with a smaller force. It can be considered that it can be pushed away.
The effect | action by this front-end | tip part 121 making a polyhedral cone shape is completely different from the form which has a rotary blade and a digging blade in a front-end | tip.
That is, the polyhedral cone does not have a cutting blade such as a spiral drill such as a rotary blade or a drilling blade, and therefore does not travel downward in the ground due to rotation. However, it can be inserted deeper into the ground with a smaller force than a structure having a cutting blade with a structure that advances downward in the ground by rotation. For example, in drilling for soil investigation, a screw point having a spiral blade is used, as defined in JIS A1221 (2013). When such a screw point is inserted into the ground, the allowable load upper limit is exceeded at a shallower position as compared with the case where the tip bit 12 having a polyhedral cone shape is used, as shown in the examples described later. It becomes impossible to insert deeply. Such a result is considered because the screw point has a part such as a blade or a blade that generates a reaction force by rotation. That is, when trying to insert a pipe into the ground with a small load, it is considered that the multi-faced cone shape can exhibit a superior propulsive force rather than having parts such as blades and blades.

Further, since the tip 121 of the tip bit 12 has a polyhedral cone shape, the tip 121 is rotated by rotating the tip, that is, by changing the direction in which the side surface 123 of the polyhedral cone 123 hits in the ground. In this case, the earth and sand around the tip bit 12 can be released. By breaking up the surrounding earth and sand, a force gap can be formed between the tip bit 12 and the surrounding earth and sand. Thereby, it is possible to suppress the next striking pressure or pressing pressure from being consumed by the side earth and sand, and to concentrate the striking pressure or pressing pressure on the tip 121 more effectively. In other words, in the case of having a blade or blade, the force due to such impact pressure or pressing is dispersed to the side by the blade or blade and escapes, so that it cannot be concentrated on the tip. It is.
In addition, by changing the position of the side surface 123 of the tip portion 121 having a polyhedral cone shape by rotation, the traveling direction of the tube can be easily maintained vertical. That is, each time the insertion progresses, it rotates along the central axis of the stainless steel tube, so that the traveling direction slightly shifted by the striking pressure or pressing is corrected.

Stainless steel tubes are made of stainless steel in the range of 15 mm to 25 mm in outer diameter, from the viewpoint of obtaining strength that does not break due to striking pressure and / or pressing, and from the viewpoint of ensuring sufficient corrosion resistance to the liquid medium and surrounding soil. Is done.
Although the kind of specific stainless steel is not specifically limited, For example, SUS304, SUS316, SUS329J3L, SUS329J4L, etc. can be used. These may use only 1 type and may use 2 or more types together.

The cross-sectional shape of the underground heat exchanger main body is not particularly limited, and may be, for example, a regular polygon such as a square, but is preferably circular. By being circular, the load applied to the pipe when the underground heat exchanger main body is inserted into the ground can be distributed in a balanced manner, and the burden on the pipe can be reduced.
Moreover, the outer diameter of the main body for underground heat exchangers is 15 mm or more and 25 mm or less. When the outer diameter is less than 15 mm, even if the wall thickness is sufficiently secured, it becomes easy to be due to its thinness, and embedment becomes more difficult. Further, the amount of the liquid medium is also reduced with a decrease in the internal voids, which is not preferable. On the other hand, when the outer diameter exceeds 25 mm, the amount of earth and sand pushed away during insertion becomes large, and it tends to be difficult to bury the earth and sand without discharging it to the ground. The outer diameter is more preferably 16 mm or more and 24 mm or less, and further preferably 17 mm or more and 23 mm or less.
In addition, when the cross-sectional shape of the underground heat exchanger main body is a shape other than a circle, the outer diameter of the underground heat exchanger main body is the outer diameter of an apparent outer circle (a virtual circle inscribed with a regular polygon). It shall be. That is, in the cross-sectional shape other than the circular shape, the outer diameter of the apparent outer circle is 15 mm or more and 25 mm or less.

One end of the stainless steel tube is liquid-tightly closed by a tip bit or a connecting part. That is, one end of the stainless steel pipe is sealed by a tip bit or a connecting part to such an extent that the liquid medium circulated inside the pipe does not leak. Moreover, this sealing naturally prevents the earth and sand from entering the pipe when the underground heat exchanger main body is inserted into the underground.
For sealing, any method such as screwing (screw-type joint or the like) or welding (similar or similar material welding or the like) may be used. Both of these can also be employed.

When a screw structure is adopted when sealing one end of the stainless steel tube with a tip bit or a connecting part, any screw structure may be adopted, but a taper screw structure is preferably adopted. By adopting a taper screw structure, a higher liquid nectar structure can be realized as compared with other screw structures.
When a screw structure is adopted, either a right-handed screw structure or a left-handed screw structure may be adopted. A screw structure that can be screwed in a direction different from the rotation direction performed in the second step can be employed so that each part of the intermediate heat exchanger main body is not disassembled.

  When a screw structure is adopted, a resin sealing member such as a membrane-like resin member or a viscous resin member is screwed with the screw portion on the stainless steel tube side to secure higher liquid tightness. It can interpose between the tip bit side or the screw part on the connecting component side. That is, for example, a resin tape is an example of the film-shaped resin member. Examples of the viscous resin member include various resin pastes and grease. These resin sealing members may use only 1 type and may use 2 or more types together.

Furthermore, although the correlation between the outer diameter and the inner diameter of the stainless steel tube is not particularly limited, the outer diameter of the stainless steel tube and D _O, the inside diameter of the stainless steel tube when the D _I, the ratio between the outer diameter and the inner diameter D _O / D _I is preferably 1.2 to 2.0. In this range, the wall thickness of the stainless steel pipe 11 can obtain a strength that can sufficiently withstand the insertion of the underground heat exchanger main body 1 into the ground, and the liquid medium flowing in the stainless steel pipe 11 can be obtained. A sufficient amount can be secured. The ratio D _O / D _I is more preferably 1.3 or more and 1.4 or less.

Moreover, although the stainless steel tube 11 may consist of the one long stainless steel tube 11, it is preferable that the individual stainless steel tube 11A is provided in a row and is made into one stainless steel tube 11. That is, the stainless steel tube 11 is preferably formed by connecting a plurality of individual stainless steel tubes 11A. The connection structure is not particularly limited, but usually a screw connection can be adopted. Any structure may be adopted as the screw structure of the individual stainless steel pipe connection portion, but a taper screw structure is preferable. The adoption of the taper screw structure can realize a higher liquid nectar structure as compared with the other screw structures as in the case described above.
In addition, when the screw structure is adopted, either a right rotation screw structure or a left rotation screw structure may be adopted. However, as in the case described above, during the rotation operation performed as the second step at the time of construction. A screw structure that can be screwed in a direction different from the rotation direction performed in the second step can be employed so that each part of the underground heat exchanger main body is not disassembled.
Furthermore, when adopting a screw structure, in order to ensure higher liquid tightness, a resin sealing member such as a membrane-like resin member or a viscous resin member is screwed with the screw portion on the stainless steel tube side. As in the case described above, it can be interposed between the tip bit side or the screw part on the connecting component side.

  Moreover, it is preferable that the stainless steel pipe 11 is 5 m or more and 15 m or less in total length irrespective of the structure. That is, in the stainless steel tube 11 in which the individual stainless steel tubes 11A are continuously provided, the total length is preferably 5 m or more and 15 m or less. By being 5 m or more, the thermostatic property in the ground can be effectively used. Moreover, by being 15 m or less, compared with the case where it is the length beyond it, while being able to improve heat exchange efficiency, insertion operation can also be performed comparatively easily. That is, by suppressing the outer diameter to a length of 15 mm or more and 25 mm or less and 15 m or less, the flow path resistance to the heat medium can be kept smaller. This length is preferably 8 m or more and 12 m or less.

  Furthermore, when the stainless steel tube 11 is formed by connecting individual stainless steel tubes 11A, the length of each individual stainless steel tube 11A is not particularly limited. For example, the individual stainless steel pipe 11A is preferably 0.5 m or more and 2 m or less. When the length of the individual stainless steel pipe 11A is within this range, it is possible to further reduce the equipment required for embedding the main heat exchanger main body 1 in the ground. That is, as illustrated in FIG. 5, after inserting the underground heat exchanger main body 1 having one individual stainless steel tube 11A into the underground 70 to a predetermined length, the rear end of the individual stainless steel tube 11A is inserted. The operation of connecting the front end of the next individual stainless steel tube 11A, applying a force from the rear end of the next individual stainless steel tube 11A, and inserting it into the ground is sequentially repeated. Can be made up. Thereby, since the length of the stainless steel tube which protrudes on the ground at the time of insertion can be shortened, the main body 1 for underground heat exchangers can be laid with smaller equipment. In addition, by shortening the length of the stainless steel tube that protrudes to the ground, the bending of the stainless steel tube can be kept small when it is pressed or pressed from the rear end side of the underground heat exchanger body to the tip bit side. The load due to the striking pressure or pressing can be reliably transmitted to the tip bit. And this length is more preferably 0.8 m or more and 1.2 m or less.

[2] Underground heat exchanger The underground heat exchanger (2) of the present invention includes a main body for underground heat exchanger (1) of the present invention,
A resin pipe (3) inserted into the stainless steel pipe,
A gap (21) formed by the resin pipe (3) and the stainless steel pipe (11) is used as a flow path of the liquid medium (4) (see FIG. 6).

The resin pipe 3 is a resin pipe having a diameter smaller than that of the stainless steel pipe 11, and the tip (the deepest part in the underground) is opened in the underground heat exchanger main body 1. The resin tube 3 can be adjusted to have low thermal conductivity by being made of resin. And it can suppress that the liquid medium distribute | circulated inside the resin tube 3 and the liquid medium distribute | circulated the outside of the resin tube 3 are heat-exchanged with low heat conductivity. Furthermore, by using a material having lower thermal conductivity, the wall thickness of the resin tube 3 can be made thinner, and the flow path in the resin tube can be made larger without changing the outer diameter of the resin tube. Can do.
Specifically, the thermal conductivity of the material constituting the resin tube 3, divided by the wall thickness of the tube 3 is preferably at 150 W / m ² or less, more preferably 100W / m ^2, 30 W / m ² or less is more preferable.
Specific resin materials constituting the resin tube 3 include polyolefin resins (polyethylene, polypropylene, etc.), vinyl chloride resins (soft vinyl chloride resin, etc.), or those made by foaming these resins to improve heat insulation performance, etc. Is mentioned. These may use only 1 type and may use 2 or more types together.

Further, the shape of the resin tube 3 is not particularly limited, and the cross-sectional shape thereof may be a circle or other shapes.
Moreover, the front-end | tip (the deepest part in the underground) should just be open | released in the main body 1 for underground heat exchangers as mentioned above, and the front-end | tip shape is not specifically limited. That is, for example, a shape cut horizontally with respect to the insertion direction of the resin tube 3 may be used, a shape cut obliquely with respect to the insertion direction, or other shapes may be used. .

Further, in the underground heat exchanger 2, a gap 21 formed by the resin tube 3 and the stainless steel tube 11 serves as a flow path for the liquid medium 4 (see FIG. 6). Further, the flow path of the liquid medium 4 is also inside the resin tube 3. Any of these flow paths may be the forward path, and any of the flow paths may be the return path. That is, the inside of the resin pipe 3 may be a forward path and the gap 21 may be a backward path, and the inside of the resin pipe 3 may be a backward path and the gap 21 may be a forward path. Furthermore, they may be designed to be interchanged as needed.
In addition, the underground heat exchanger 2 of this invention becomes the length substantially the same as the length of the main body 1 for underground heat exchangers. That is, the length of the underground heat exchanger 2 is preferably 5 m or more and 15 m or less.

[3] Ground heat exchange system The ground heat exchange system 5 of the present invention includes a ground heat exchanger 2 of the present invention,
Liquid medium circulation means 51 for circulating the liquid medium 4 in the underground heat exchanger 2.

In the underground heat exchange system 5 of the present invention, only one underground heat exchanger 2 described above may be provided, but it is more preferable to provide two or more underground heat exchangers because heat exchange performance can be improved. That is, the number can be adjusted according to the heat exchange performance required at the place of installation. That is, for example, in a normal house for four people, the total length of the heat exchanger is about 100 m (corresponding to about 10 when the length of one heat exchanger is 10 m). It is suitable to do.
In addition, when a plurality of underground heat exchangers 2 are provided, these underground heat exchangers 2 may be connected in parallel to the flow path of the liquid medium, or may be connected in series. Although it is good, it is more preferable to connect in parallel. This is because, by connecting in parallel, the temperature difference between the temperature of the liquid medium entering the heat exchanger and the temperature in the ground is higher than in the case of connecting in series, so that the heat exchange efficiency is excellent. In addition, because the length of the flow path until the liquid medium enters and exits the heat exchanger can be kept short, the piping resistance is low, and it is easy to circulate the liquid medium to the heat exchanger with a smaller pump. .

Moreover, the kind of liquid medium 4 used in the underground heat exchange system 5 of the present invention is not particularly limited, and examples thereof include water, various aqueous solutions containing a solute, alcohol-based liquid medium, glycol-based liquid medium, and the like. Among these, examples of the solute contained in the aqueous solution include inorganic chlorides (calcium chloride, sodium chloride, etc.) and organic acid salts (potassium acetate, sodium acetate, etc.). These solutes may be used alone or in combination of two or more. Examples of the alcohol liquid medium include ethanol and isopropyl alcohol. These alcohol liquid media may use only 1 type and may use 2 or more types together. Further, examples of the glycol-based liquid medium include ethylene glycol and propylene glycol. These glycol-type liquid media may use only 1 type, and may use 2 or more types together. Furthermore, these various liquid media may use only 1 type, and may use 2 or more types together.
In the underground heat exchange system 5 of the present invention, among these liquid media, water (no solute) and / or alcohol-based liquid media are preferable, and in particular, 50% by volume with respect to 100% by volume of the entire liquid medium. A liquid medium containing the above water is preferred.

  As the liquid medium circulation means 51, as shown in FIG. 7, the flow path 51A for supplying or discharging the liquid medium to the resin tube 3 or the liquid medium to the stainless tube 11 or the stainless tube 11 and the flow path 51B for discharging | emitting from 11 is mentioned. Furthermore, a pump (not shown in FIG. 7) for circulating the liquid medium is included. In addition, a configuration such as a thermometer, a pressure gauge, a flow meter, and an adjustment tank can be provided. These various structures may use only 1 type and may use 2 or more types together.

[4] Construction method of the underground heat exchange system The construction method of the underground heat exchange system of the present invention is a construction method of the underground heat exchange system of the present invention,
After placing the tip of the tip bit on the ground so that the main body for the underground heat exchanger is substantially perpendicular to the ground, the ground heat is applied by pressing or pressing from the rear end side toward the tip bit side. A first step of applying a load to the exchanger body;
A second step of rotating the underground heat exchanger body so that the tip bit is rotated in the ground,
The first step and the second step are performed simultaneously or alternately.

The first step is to stand the tip of the tip bit 12 on the ground so that the underground heat exchanger main body 1 is substantially perpendicular to the ground, and then toward the tip bit 12 from the rear end 112 side. This is a step of applying a load to the underground heat exchanger main body 1 by striking pressure or pressing.
The impact force when performing the impact is not particularly limited, but is preferably 100 kgf (980 N) or more. Further, if the impact force is too high, the stainless steel tube may be damaged. Therefore, it is preferably 1000 kgf (9800 N) or less. The impact force is more preferably 100 kgf (980 N) or more and 600 kgf (5880 N) or less.
Moreover, although the load in the case of performing a press is not specifically limited, It is preferable that it is 10 kgf (98N) or more. Further, if the load is too high, the stainless steel tube protruding on the ground is broken, and it becomes difficult to insert it straight into the ground, so that it is preferably 100 kgf (980 N) or less. This load is more preferably 20 kgf (196 N) or more and 100 kgf (980 N) or less.
In the first step, both of the impact pressure and the pressure may be applied, or only one of them may be applied.

  The second step is a step of rotating the underground heat exchanger main body 1 so that the tip bit 12 is rotated in the ground. By this rotation, the earth and sand around the tip bit 12 can be solved. In general, the rotation at this time is preferably 60 ° or more. Further, it may be continuously rotated 360 degrees in one direction, or a predetermined number of rotations may be alternately performed left and right.

In this method, the first step and the second step are performed simultaneously or alternately.
These first step and second step may be performed simultaneously or may be performed alternately. That is, in the case of performing simultaneously, the pressure (first step) is simultaneously applied while rotating (second step) and / or the pressure (first step) is simultaneously performed while rotating (second step). , That means. Moreover, the case where it carries out separately means rotating (2nd process) after making it strike and / or press (1st process).

Hereinafter, the present invention will be specifically described by way of examples.
[1] Embedding test of main body for underground heat exchanger A test was conducted in which 1 was actually buried in the ground using a plurality of types of tip bits 12 having different shapes. That is, the main body 1 for underground heat exchanger having the following six types of configurations was manufactured.

(1) Example 1
As the individual stainless steel tube 11A, SUS304 having an outer diameter of 22 mm and a length of 1 m was used. Each individual stainless steel tube has a structure in which a rear end of one individual stainless steel tube 11A and a front end of another individual stainless steel tube 11A can be screwed together and connected by a taper screw.
Further, as the tip bit 12, a tip bit 12 made of SUJ2 having the general shape shown in FIG. 3, W of 22.0 mm, L of 33.9 mm, θ of 18 ° and subjected to quenching and tempering was prepared. .
The tip bit 12 was screwed and fixed to the tip of one individual stainless steel tube 11A via a connection component 13 (FIG. 1) having a length of 30 mm. The distal end side of the individual stainless steel tube 11 </ b> A is liquid-tightly sealed by the connection component 13.
The ground heat exchanger main body 1 prepared in this manner is hit 5 times (1 by striking the rear end of the main body 1 for underground heat exchanger using a 10 kg hammer while maintaining a direction perpendicular to the ground. After performing the first step of impact force of about 200 kgf (1960 N)), the second step of rotating the underground heat exchanger main body 1 five times while maintaining the vertical is performed, and this operation is sequentially repeated. The main body 1 for underground heat exchanger was inserted into the ground. Further, when the individual stainless steel pipes 11A were buried and the length of the stainless steel pipe 11A protruding to the ground became a small size, a new individual stainless steel pipe 11A was added to continue the work (see FIG. 5). These operations were repeated and the work was completed when the depth reached 15 m.

(2) Example 2
As the individual stainless steel tube 11A, SUS304 having an outer diameter of 20 mm and a length of 1 m is used, and the tip bit 12 has the general shape shown in FIG. 4, and W is 19.4 mm, L is 29.5 mm, and θ is 18 °. Yes, a tip bit 12 made of SUJ2 subjected to quenching and tempering was used.
The ground heat exchanger main body 1 thus prepared is always loaded with a vertical load of 100 kg and maintained in a direction perpendicular to the ground, using a 10 kg hammer for the underground heat exchanger main body 1. After performing the first step of hitting the rear end five times (one impact force of about 200 kgf (1960 N) by hitting), the second step of rotating the underground heat exchanger main body 1 five times while maintaining verticality The underground heat exchanger main body 1 was inserted into the ground by sequentially repeating these operations.
As a result, it was possible to embed up to 10 m without problems.

(3) Example 3
The tip bit 12 has the general shape shown in FIG. 4, except that W is 24.7 mm, L is 37.4 mm, θ is 18 °, and the tip bit 12 made of SUJ2 subjected to quenching and tempering is used. The operation was performed in the same manner as in Example 1. As a result, it was possible to embed up to 15m without any problem.

(4) Example 4
The tip bit 12 has the general shape shown in FIG. 3 except that a tip bit 12 made of SUJ2 with W of 22.0 mm, L of 15.6 mm, and θ of 35 ° and subjected to quenching and tempering is used. The operation was performed in the same manner as in Example 1. As a result, it was possible to embed up to 10 m without problems.

(5) Example 5
As the tip bit 12, except for using a SUJ2 tip bit 12 having the general shape shown in FIG. 4, W of 19.4 mm, L of 13.8 mm, θ of 35 °, and quenching and tempering. The operation was performed in the same manner as in Example 1. As a result, it was possible to embed up to 10 m without problems.

(6) Example 6
The tip bit 12 has the general shape shown in FIG. 4, except that W is 24.7 mm, L is 17.5 mm, θ is 35 °, and the tip bit 12 made of SUJ2 subjected to quenching and tempering is used. The operation was performed in the same manner as in Example 1. As a result, it was possible to embed up to 10 m without problems.

(7) Comparative Example 1
As the tip bit 12, a screw point conforming to JIS A1221 (2013) was used. The screw point has a total length of 200 mm, a maximum diameter of 33 mm, and a shape having cutting blades for one rotation in total. In this configuration, the operation was performed in the same manner as in Example 1, but the resistance during rotation increased from a depth of about 3 m, and the torque required for rotation exceeded 200 N · m when it reached 3.5 m. Burying was suspended due to difficulties. Thus, it is thought that the cause of the increase in rotational torque is that the screw point has a cutting edge, so that the earth and sand enter between the cutting edges and the earth and sand become resistance.
The rotational torque during work in Examples 1 to 6 was in the range of 25 to 100 N · m, and the work could be performed without any problem. That is, in the main body for the underground heat exchanger of Examples 1 to 6, since there is no cutting edge or the like in the tip bit, there is no room for the above-mentioned earth and sand to enter, and the accompanying resistance did not occur, It is thought that it was able to be buried smoothly.

1; Main body for underground heat exchanger,
11; stainless steel pipe, 111; one end, 112; rear end, 11A; individual stainless steel pipe,
12; tip bit, 121; tip portion, 122; bottom surface, 123; side surface, 124; ridgeline, 12A;
13; connecting parts,
2; underground heat exchanger, 21; gap,
3; resin pipe,
4; liquid medium,
5; underground heat exchange system, 51; liquid medium circulation means, 51A and 51B; flow path of liquid medium,
70; Underground,
90; Borehole, 91; Earth wall, 92; Casing, 93; Water, 94; Tube tube, 95; Sand.

Claims (11)

It is a main body for a ground heat exchanger used in a ground heat exchanger that performs heat exchange between the liquid medium that is circulated inside the tubular body buried in the ground and the ground,
A stainless steel tube having an outer diameter of 15 mm to 25 mm;
A tip bit that is connected to one end side of the stainless steel pipe and has a tip portion having a polyhedral conical shape disposed with the bottom face facing the one end;
The one end of the stainless steel pipe is liquid-tightly closed by the tip bit or by a connecting part interposed between the stainless steel pipe and the tip bit,
The bottom surface of the tip bit is the same as or larger than the outer periphery of the one end of the stainless steel tube,
The main body for an underground heat exchanger, wherein the polyhedral conical shape has three or more and eight or less side surfaces.   The main body for an underground heat exchanger according to claim 1, wherein an angle between a central axis of the tip bit and a side surface of the tip portion forming the polyhedral cone shape forming the tip bit is 15 degrees or more and 40 degrees or less. The outer diameter of the stainless steel tube and D _O, the inside diameter of the stainless steel tube in case of a D _I, claim ratio D _{O /} D _I between the outer diameter and inner diameter is 1.2 to 2.0 The main body for underground heat exchangers as described in 1 or 2.   The main body for an underground heat exchanger according to any one of claims 1 to 3, wherein the stainless steel pipe is formed by connecting a plurality of individual stainless steel pipes.   The length of the said stainless steel pipe is 5 m or more and 15 m or less, The main body for underground heat exchangers in any one of Claims 1 thru | or 4. A main body for an underground heat exchanger according to any one of claims 1 to 5,
A resin tube inserted into the stainless steel tube,
A ground heat exchanger characterized in that a gap formed by the resin pipe and the stainless steel pipe is used as a flow path for the liquid medium. The underground heat exchanger according to claim 6,
A ground heat exchange system comprising: a fluid medium circulation means for circulating the fluid medium in the underground heat exchanger.   The underground heat exchange system according to claim 7, comprising two or more underground heat exchangers.   The underground heat exchange system according to claim 8, wherein the underground heat exchanger is connected in parallel to the flow path of the liquid medium.   The underground heat exchange system according to any one of claims 7 to 9, wherein the liquid medium contains 50% by volume or more of water when the whole is 100% by volume. It is the construction method of the underground heat exchange system in any one of Claims 7 thru | or 10,
After standing the tip of the tip bit on the ground so that the main body for an underground heat exchanger is substantially perpendicular to the ground, it is struck or pressed from the rear end side toward the tip bit side. , A first step of applying a load to the underground heat exchanger main body;
A second step of rotating the underground heat exchanger main body so that the tip bit is rotated in the ground,
The construction method for the underground heat exchange system, wherein the first step and the second step are performed simultaneously or alternately.

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