JP2011007446A - Underground heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground heat exchanger for improving performance of execution of installation work of the underground heat exchanger and reducing installation cost.SOLUTION: The underground heat exchanger performing heat exchange with a ground includes: a flexible resin corrugated pipe arranged within an excavation on the ground; a discharge port for discharging a heating medium to inside of the corrugated pipe; an emission port for emitting the heating medium which has undergone heat exchange with the ground from the corrugated pipe; and a filler filled between the excavation and the corrugated pipe. The corrugated shape of the corrugated pipe is set to be a spiral shape using a pipe axis of the corrugated pipe as a central axis. One pipe end of the corrugated pipe is sealed by a cap member screwed to a part of the corrugated shape at the pipe end serving as a screw part.

Description

  The present invention relates to an underground heat exchanger that exchanges heat with the ground.

  A geothermal heat utilization system that heats and cools buildings using geothermal heat with small year-round temperature fluctuations is attracting attention. In this geothermal heat utilization system, a geothermal heat exchanger is installed in the ground to collect and radiate heat with the ground. The underground heat exchanger, for example, radiates heat to the ground in summer and collects heat from the ground in winter.

  As an example, Patent Document 1 discloses a double-pipe underground heat exchanger. That is, as shown in the longitudinal sectional view of FIG. 1A, the underground heat exchanger 121 includes a steel pipe 131 as an outer cylinder vertically embedded in the ground G, and a polyethylene as an inner cylinder disposed in the steel pipe 131. And a pipe 141 (hereinafter referred to as a PE pipe). Then, the heat medium 26 that has flowed into the steel pipe 131 from the inlet 131a provided at the upper end of the steel pipe 131 is taken out from the outlet 141a at the lower end of the PE pipe 141, thereby exchanging heat with the ground G. The subsequent heat medium 26 is sent to a heat pump or the like.

  By the way, this patent document 1 shows a structure as shown in FIG. 1B as a sealing structure of the pipe end opening 131b on the lower side of the steel pipe 131. That is, the annular portion 132 is provided so as to protrude inward from the inner peripheral surface of the steel pipe 131, and the flange plate 142 that is abutted and fixed to the lower end surface of the PE pipe 141 is applied to the entire circumference of the annular portion 132. It is shown that sealing is achieved by contact. Further, it is also shown that a nichrome wire 145 is wired between the annular portion 132 and the flange plate 141 in order to improve the sealing performance, and the flange plate 141 is melted and welded to the annular portion 132 by energization. Yes.

Japanese Patent Laid-Open No. 2002-13828

  However, such a sealing structure is complicated as described above, and the annular portion 132 must be provided for each steel pipe 131, which increases the number of work steps and increases the work cost.

  Moreover, since the steel pipe 131 is used for the outer cylinder, the material cost is high, and the weight of the steel pipe is heavy, so that it is difficult to build it into the borehole 123 of the ground G, and a heavy lifting machine is not used. However, the construction scale becomes large. Furthermore, since it is impossible to wind the steel pipe 131 in a coil shape when it is transported to the construction site, it is difficult to make it compact. As a result, the transportability is inferior. It was a cause.

  The present invention has been made in view of the conventional problems as described above, and provides a ground heat exchanger capable of improving the workability of the installation work of the underground heat exchanger and reducing the installation cost. With the goal.

In order to achieve this object, the invention shown in claim 1
An underground heat exchanger that exchanges heat with the ground,
A flexible resin corrugated pipe disposed in the excavation hole of the ground;
A discharge port for discharging a heat medium into the corrugated tube;
A discharge port for discharging the heat medium exchanged with the ground from the corrugated pipe;
A filler filled between the excavation hole and the corrugated pipe,
The corrugated shape of the tube wall portion of the corrugated tube is formed in a spiral shape with the tube axis of the corrugated tube as the central axis,
One end of the corrugated tube is sealed by a cap member that is screwed with the corrugated portion at the end of the tube as a threaded portion.

  According to the first aspect of the present invention, the cap member uses a corrugated pipe (corrugated pipe) as a threaded portion to be screwed when sealing the pipe end. . Therefore, it is not necessary to separately provide a fixing structure for fixing the cap member to the pipe end portion, and the configuration of the corrugated pipe can be simplified. Further, since the tube end can be sealed by screwing the cap member into the tube end, the sealing operation is facilitated.

Further, since the corrugated pipe is made of resin and light in weight, it is easy to install the corrugated pipe, for example, without using a heavy lifting machine when installing the corrugated pipe into the excavation hole.
Furthermore, the corrugated tube has flexibility. Therefore, even if the total length is several tens of meters to several hundreds of meters, the corrugated tube can be wound into a compact size and stored in a compact size, and can be easily transported to the construction site.
Moreover, since it is a corrugated pipe | tube, the shape of the pipe wall part becomes a waveform shape, and, thereby, the surface area of the internal peripheral surface of a pipe wall part and an outer peripheral surface is expanded. Therefore, the heat exchange efficiency between the ground and the heat medium in the corrugated pipe can be remarkably improved by the enlarged surface area.

The invention shown in claim 2 is the underground heat exchanger according to claim 1,
The pipe end portion sealed with the cap member is filled with a grout material of a cement-based material or a resin-based material so as to straddle the cap member and the tube end portion.
According to the second aspect of the present invention, even when there is a meshing gap in the screwing range in which the cap member and the pipe end are screwed, the meshing gap can be closed by the grout material. The external leakage of the heat medium from the pipe end of the corrugated pipe can be reliably prevented.

The invention shown in claim 3 is the underground heat exchanger according to claim 2,
The corrugated pipe is inserted along the vertical axis of the corrugated pipe into the borehole drilled in the vertical direction on the ground as the excavation hole,
The pipe end part on the lower side in the vertical direction of the corrugated pipe is sealed by the cap member, and the grout material is filled in the pipe end part.

  According to the third aspect of the present invention, the corrugated tube can be easily inserted when inserted into the fistula. Details are as follows. The depth of the corrugated tube built into the fistula generally reaches several tens of meters to several hundreds of meters. Further, the corrugated tube is made of resin, and the built-in posture tends to become unstable due to bending due to its flexibility. For this reason, when the corrugated tube is inserted into the fistula, there is a possibility that the lower end of the corrugated tube is caught by the hole wall of the fistula and clogged, so that it cannot be quickly inserted to the bottom of the fistula.

  In this regard, according to the above-described configuration, the grout material filled in the lower pipe end portion of the corrugated pipe becomes a weight, that is, the weight pulls the corrugated pipe downward and extends straight. Therefore, it is possible to effectively prevent troubles such as the pipe end on the lower side of the corrugated pipe being caught by the hole wall of the fistula, and the corrugated pipe can be easily built into the fistula.

Invention of Claim 4 is the underground heat exchanger in any one of Claims 1 thru | or 3, Comprising:
On the inner peripheral surface of the cap member, a female screw is formed which is screwed with the corrugated portion on the outer peripheral surface of the tube end as a male screw,
The cap member seals the tube end portion while covering the tube end portion from the outside.
According to the fourth aspect of the present invention, the cap member is screwed onto the outer peripheral surface while covering the outer peripheral surface of the pipe end portion. Therefore, the cap member can reliably seal the tube end.

Invention of Claim 5 is the underground heat exchanger in any one of Claims 1 thru | or 4, Comprising:
The filler filled between the excavation hole and the corrugated pipe contains a long particle made of at least one of silicon carbide, alumina, and blast furnace slag at a predetermined volume content. It is characterized by that.

  According to the fifth aspect of the present invention, the long particles contained in the filler are made of at least one of silicon carbide, alumina, and blast furnace slag, and all of the materials have high thermal conductivity. is doing. Moreover, since the shape is a long grain shape, the probability that the long grain objects which adjoin each other in a filler will become high, and, thereby, it becomes easy to form a heat path in the said filler. That is, it is possible to reliably form a heat transfer path with high thermal conductivity in the filler without increasing the content of the long particles. Therefore, even if the above-mentioned long particles are more expensive than sand or the like generally used as a filler, the thermal conductivity of the filler is reliably increased while keeping the manufacturing cost of the underground heat exchanger low. Can do.

The invention shown in claim 6 is the underground heat exchanger according to claim 5,
The longitudinal dimension of the long particles is 10 to 50 mm,
The dimension in a direction orthogonal to the longitudinal direction is 1 to 3 mm.

  According to the invention described in claim 6 above, since the longitudinal dimension of the long grains is 10 mm or more, the probability that the long grains adjacent to each other will be in contact with each other increases. The rate of heat transfer path can be reliably formed. Moreover, since it is 50 mm or less, manufacture of a long grain thing is not so difficult and the rise in manufacturing cost can be suppressed. Furthermore, if it is longer than 50 mm, it tends to be broken when filling the excavation hole, and there is a possibility that a problem of cost-effectiveness deterioration that a long particle after filling cannot be lengthened for the manufacturing cost may occur. However, if it is 50 mm or less, this problem can be effectively avoided.

  Moreover, 1-3 mm which is the dimension of the direction orthogonal to the longitudinal direction of a long grain is generally the same size as the grain size of granular materials, such as sand, generally used as a base material of a filler. Therefore, the long particles are easily mixed uniformly without being unevenly distributed in the base material of the filler, and as a result, high thermal conductivity can be ensured over the entire area of the filler.

  Incidentally, according to the dimension range of the granular material described above, the minimum size of the long granular material is 10 mm × 1 mm. Therefore, it is possible to surely prevent the problem that long particles flow out of the filler when mixed with groundwater, which tends to occur when the particle size is micron-order fine powder, and the filler has a high thermal conductivity over a long period of time. Can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the construction property of the installation work of a ground heat exchanger can be improved, and the ground heat exchanger which can reduce installation cost can be provided.

FIG. 1A is a longitudinal sectional view of a conventional underground heat exchanger 121 having a double-pipe structure, and FIG. 1B is an explanatory diagram of a sealing structure of a tube end opening 131b of a steel pipe 131 which is an outer tube of the double-pipe structure. It is. It is explanatory drawing of the underground heat utilization system 11 using the underground heat exchanger 21 which concerns on this embodiment. It is a longitudinal cross-sectional view of the underground heat exchanger 21 which concerns on this embodiment, and has shown the one part by side view. 4A and 4B are explanatory diagrams of examples of use in winter and summer, respectively, and both show the underground heat exchanger 21 in a longitudinal sectional view. It is a perspective view of the corrugated pipe | tube 31 used for the outer cylinder of the underground heat exchanger 21. FIG. It is explanatory drawing of the desirable example which concerns on this embodiment. It is explanatory drawing of the other desirable example which concerns on this embodiment. FIG. 7A is an explanatory view of the filler 27 containing long particles 27a of silicon carbide, and FIG. 7B is an explanatory view of the filler 27 containing spherical silicon carbide as a comparative example. These are explanatory drawings of the heat transfer path (heat bridge) of the high thermal conductivity which the long grain 27a of FIG. 7A forms in the filler 27. FIG. FIG. 8A thru | or FIG. 8F are explanatory drawings of the installation method of the underground heat exchanger 21 which concerns on this embodiment. It is explanatory drawing of the unfilled part of the filler 27 which may arise in the outer peripheral surface 31c of the corrugated pipe | tube 31. FIG.

=== This Embodiment ===
<<< About the underground heat exchanger 21 >>>
FIG. 2 is an explanatory diagram of the underground heat utilization system 11 using the underground heat exchanger 21 according to the present embodiment. FIG. 3 is a longitudinal sectional view of the underground heat exchanger 21 partially shown in a side view. 4A and 4B are longitudinal sectional views of the underground heat exchanger 21 showing usage examples in winter and summer, respectively. FIG. 5 is a perspective view of the corrugated pipe 31 used for the outer cylinder of the underground heat exchanger 21. In addition, about FIG. 3 thru | or FIG. 4B, in order to prevent the confusion of a figure, the cross section line which should be provided to a cross-sectional site | part is abbreviate | omitted.

  As shown in FIG. 2, the geothermal heat utilization system 11 utilizes the heat from the underground heat exchanger 21 that performs heat exchange with the ground G and the heat medium 26 of the underground heat exchanger 21. And a heat pump 15 that generates hot water for heating the building 1 and cold water for cooling. In addition, since the structure of the heat pump 15 is known, the description is abbreviate | omitted.

  As shown in FIG. 3, the underground heat exchanger 21 is a borehole type double pipe type. That is, a borehole 23 as an excavation hole formed vertically in the ground G, a corrugated pipe 31 as an outer cylinder inserted along the vertical direction into the borehole 23, and a first disposed in the corrugated pipe 31. The first hose member 41 as the inner cylinder, the second hose member 45 as the second inner cylinder arranged in the corrugated pipe 31, and the space SP23 between the bore 23 and the corrugated pipe 31 are filled. And a filler 27.

  For example, in winter, as shown in FIG. 4A, a heat medium 26 such as water or antifreeze is sent from the heat pump 15 via the first hose member 41, and the heat medium 26 is a corrugated pipe 31. Is discharged into the corrugated pipe 31 from a pipe end opening 41e (corresponding to a “discharge port”) of the first hose member 41 arranged at the lower end 31a of the first hose member 41. Then, the heat medium 26 is heated by the underground heat of the ground G in the corrugated pipe 31 and moves upward in the corrugated pipe 31 based on natural convection, and thereafter, provided in the upper end portion 31 b of the corrugated pipe 31. The second hose member 45 flows into the second hose member 45 from the tube end opening 45e (corresponding to the “discharge port”) and is sent out toward the heat pump 15. Then, the heat pump 15 is used to generate hot water.

  On the other hand, the flow direction of the heat medium 26 in the summer is reversed as described above. That is, as shown in FIG. 4B, the heat medium 26 is sent from the heat pump 15 via the second hose member 45, and the heat medium 26 passes through the tube end opening 45 e (“discharge port” of the second hose member 45. To the corrugated pipe 31. Then, the heat medium 26 is cooled by the ground heat of the ground G in the corrugated pipe 31 and moves downward in the corrugated pipe 31 based on natural convection, and then provided at the lower end portion 31 a of the corrugated pipe 31. The first hose member 41 flows into the first hose member 41 from the pipe end opening 41e (corresponding to the “discharge port”) and is sent out toward the heat pump 15. Then, the heat pump 15 is used for cold water generation.

  Hereinafter, each component 23,31,41,45,27 which concerns on the underground heat exchanger 21 is demonstrated in detail.

(1) Fist hole 23
As shown in FIG. 3, the hole 23 is a hole excavated almost perpendicularly to the ground by an excavator such as an auger, and has a diameter of 100 to 200 mm and a depth of 30 to 150 m.

(2) Corrugated pipe 31
As shown in FIGS. 5 and 3, the corrugated tube 31 is a tube member having a corrugated tube wall. This corrugated shape is a spiral shape with the tube axis C31 of the corrugated tube 31 as the central axis, and the thickness (wall thickness) of the tube wall portion is substantially constant over the entire length. Therefore, both the outer peripheral surface 31c and the inner peripheral surface 31d of the corrugated pipe 31 have substantially the same spiral waveform. More specifically, as shown in FIG. 3, the crest portion related to the spiral waveform shape of the outer peripheral surface 31 c and the trough portion related to the spiral waveform shape of the inner peripheral surface 31 d, or the trough portion related to the spiral waveform shape of the outer peripheral surface 31 c The crests related to the helical corrugated shape of the peripheral surface 31d are located next to each other in the wall thickness direction.

  And since the surface area of the outer peripheral surface 31c and inner peripheral surface 31d of a pipe wall part is expanded by such a spiral waveform shape, the heat exchange efficiency between the ground G and the heat medium 26 in the corrugated pipe 31 is It is greatly improved.

  Further, various parameters that define the helical waveform shape (for example, the pitch P between the crests and the crests in the direction of the tube axis C31 (or the pitch P between the troughs and the crevices in the direction of the tube axis C31), the outer diameter D1 of the crests. , The outer diameter D2 of the valleys, etc.) are the same specification over the entire length of the corrugated pipe 31. Therefore, any part of the tube wall portion of the corrugated tube 31 can function as a male screw or a female screw as necessary. Examples of use as the male screw or the female screw will be described later.

  A cap member 33 is provided at the lower end 31a of the corrugated pipe 31 (corresponding to “one pipe end” or “lower pipe end”) to seal the pipe end opening 31ed of the lower end 31a. Yes. This prevents the heat medium 26 in the corrugated pipe 31 from leaking from the pipe end opening 31ed to the ground G.

  Specifically, the cap member 33 includes a cylindrical portion 33a and a substantially conical portion 33b that extends coaxially and integrally from the cylindrical portion 33a in the tube axis direction. The cylindrical portion 33a has a spiral waveform portion corresponding to the spiral waveform shape of the corrugated tube 31 on its inner peripheral surface 33c. The spiral waveform portion is an internal thread, and the lower end portion 31a of the corrugated tube 31 The cap-shaped member 33 is screwed into the lower end portion 31a of the corrugated tube 31, and the tube end opening 31ed of the lower end portion 31a of the corrugated tube 31 is sealed. Stop. That is, the cap member 33 is screwed and fixed to the corrugated pipe 31 using the spiral waveform shape of the corrugated pipe 31. Therefore, it is not necessary to add a special fixing structure for fixing the cap member 33 to the lower end portion 31a of the corrugated pipe 31, and the configuration of the corrugated pipe 31 can be simplified. Further, if the cap member 33 is screwed into the lower end portion 31a of the corrugated pipe 31, the lower end portion 31a can be sealed, so that the sealing work is facilitated.

  On the other hand, a cap member 35 is also provided at the upper end 31b of the corrugated pipe 31 so as to seal the pipe end opening 31eu of the upper end 31b. The cap member 35 is, for example, a solid cylindrical body, and a male screw is formed on the outer peripheral surface 35c. And the part of the inner peripheral surface 31d of the upper end part 31b of the corrugated pipe 31 is a female screw, and the male screw of the cap member 35 is screwed together, thereby sealing the pipe end opening 31eu of the upper end part 31b. It is like that. The cap member 35 is formed with through holes 35h and 35h for guiding the first hose member 41 and the second hose member 45 described above into the corrugated pipe 31, and these through holes 35h and 35h The first hose member 41 and the second hose member 45 are passed through, respectively.

Such a corrugated pipe 31 is made of a resin such as high-density polyethylene and is much lighter than a steel pipe. Therefore, when the corrugated pipe 31 is built into the borehole 23 of the ground G, it is not necessary to use a heavy lifting machine.
Moreover, since it has flexibility, even if the total length is several tens of meters to several hundreds of meters, the corrugated tube 31 can be wound into a reel and stored in a compact size. This makes it easy to transport to the construction site.

  Desirably, as shown in FIG. 6A, a grout material 37 made of a cement-based material or a resin-based material is connected to the lower end portion 31 a of the corrugated pipe 31 sealed with the cap member 33. It is good to be filled so as to straddle 31a. In this case, even when a slight meshing gap S1 exists between the female thread of the cap member 33 and the male thread of the lower end portion 31a of the corrugated pipe 31, the grout material 37 enters the meshing gap S1, The gap S <b> 1 can be reliably closed by the grout material 37, and as a result, the external leakage of the heat medium 26 from the lower end portion 31 a of the corrugated pipe 31 can be reliably prevented.

  Further, if such a filling portion of the grout material 37 is provided at the lower end portion 31 a of the corrugated pipe 31, the grout material 31 is inserted when the corrugated pipe 31 is inserted into the fistula 23 in the installation work of the underground heat exchanger 21. It becomes easy to insert 37 as a weight. Details are as follows.

  The depth of the corrugated pipe 31 built into the fistula 23 generally reaches several tens of meters to several hundreds of meters. On the other hand, the corrugated pipe 31 is made of resin, and its built-up posture tends to be unstable, such as bending or swaying in small increments due to its flexibility. As a result, when the corrugated pipe 31 is inserted into the borehole 23, the lower end portion 31a of the corrugated pipe 31 is caught by the hole wall 23a of the borehole 23 and clogged, so that it quickly reaches the vicinity of the bottom portion of the borehole 23. There is a risk of not.

  About this point, according to the above-mentioned structure, the grout material 37 with which the lower end part 31a of the corrugated pipe | tube 31 was filled becomes a weight, and, thereby, the corrugated pipe | tube 31 is pulled down and it is in the state extended straightly. Therefore, the lower end portion 31 a of the corrugated pipe 31 is not easily caught by the hole wall 23 a of the hole 23, and is easily built into the hole 23.

  Moreover, depending on the kind of installation method of the underground heat exchanger 21, there is a case where the liquid material is filled in the borehole 23 when or after the corrugated pipe 31 is inserted into the borehole 23 of the ground G. is there. In such a case, the corrugated pipe 31 is lifted by buoyancy from the liquid material, and may not be inserted into the fistula 23. In such a case, the grout material 37 described above may be corrugated pipe. It effectively functions as a weight that resists the buoyancy of 31, whereby the lower end portion 31 a of the corrugated pipe 31 is quickly and straightly settled into the liquid material in the fistula 23. Incidentally, in order to reliably counter such buoyancy, a liquid such as water may be put into the corrugated pipe 31 and the corrugated pipe 31 may be inserted into the fistula 23 while using the liquid as a weight.

  As such a grout material 37, a cement-based material or a resin-based material that has fluidity at the time of filling and solidifies after filling is used. Specific examples of the cement-based material include cement and mortar. Specific examples of the resin-based material include epoxy resin, acrylic resin, and silicon resin. Incidentally, when used as a weight, a material having a high specific gravity after solidification is preferable. For example, when the pores 23 are filled with a liquid material as described above, a material having a higher specific gravity than the liquid material is used. It is good to use as the grout material 37.

  The filling process of the grouting material 37 is performed as follows on the ground before the corrugated pipe 31 is built in the fistula 23. First, in a state where the cap member 33 is screwed into the corrugated tube 31 and the tube end opening 31ed is sealed, the corrugated tube 31 is disposed so that the bottom 33f of the cap member 33 is positioned below. And two through-holes h1 and h2 which connect the inside of the corrugated pipe 31 and external space are formed in the site | part of the pipe wall part above the screwing part of the cap member 33 and the corrugated pipe 31, or a screwing part. . One of these through holes h 1 is used as an injection hole for injecting the grout material 37 into the corrugated pipe 31, and the other through hole h 2 is a hole for visual confirmation of the filling height of the grout material 37. used. That is, the latter hole h <b> 2 is formed at a position corresponding to the target filling height of the grout material 37. Then, when the grout material 37 is injected from the hole h1 and the grout material 37 leaks from the hole h2, the injection of the grout material 37 is stopped, and the holes h1 and h2 are pressed from the outside by a plate until the grout material 37 is solidified. And then remove the plate after solidification.

  Incidentally, as a filling structure of the grout material 37 that seals the lower end portion 31a of the corrugated pipe 31, for example, a structure as shown in FIG. That is, in the example of FIG. 6B, only the lower end portion 31a of the corrugated pipe 31 is filled with resin or the like as the grout material 37 to close the pipe end opening 31ed of the lower end portion 31a. 37 is not filled, but this may be used.

(3) First hose member 41 and second hose member 45
As shown in FIG. 3, the 1st hose member 41 and the 2nd hose member 45 are resin-made pipe members, such as polyethylene, for example. And the pipe end opening 41e at the lower end of the first hose member 41 is arranged at the lower end 31a of the corrugated pipe 31, while the pipe end opening 45e at the lower end of the second hose member 45 is It arrange | positions at the upper end part 31b. As a result, the heat medium 26 rises or descends in the corrugated pipe 31 based on natural convection or the like through the route of FIG. 4A described above in winter and the route of FIG. 4B described above in summer. Exchange.

(4) Filler 27
The filler 27 is, for example, river sand, mountain sand, quartz sand, or the like as a base material 27b, and is densely filled into the space SP23 between the corrugated pipe 31 and the fistula 23. Thereby, heat exchange is performed between the heat medium 26 in the corrugated pipe 31 and the ground G through the filler 27.

  In order to increase this heat exchange efficiency, as shown in FIG. 7A, the filler 27 has a volume content of 1 to 20% (= total volume of the long granules 27a / total volume of the filler 27). , Alumina, and long grain 27a made of at least one of blast furnace slag is mixed. In this example, silicon carbide 27a is mixed. And the thermal conductivity of the silicon carbide 27a is as high as 168 (W / mK). Therefore, the thermal conductivity of the filler 27 is drastically increased by the inclusion of the silicon carbide 27a.

  The shape of the silicon carbide 27a is a long grain shape (needle shape, rod shape). Therefore, as shown in FIG. 7A, the probability that the silicon carbides 27a and 27a adjacent to each other in the filler 27 are in contact with each other is significantly higher than that of the spherical shape shown in FIG. 7B. Inside, a heat path (heat bridge) as shown in FIG. 7C is easily formed. That is, a heat transfer path having a high thermal conductivity can be reliably formed in the filler 27 without increasing the content of the silicon carbide 27a so much. Therefore, the content rate of the silicon carbide 27a more expensive than sand can be reduced, and as a result, the thermal conductivity of the filler 27 is reliably increased while the manufacturing cost of the underground heat exchanger 21 is kept low. be able to.

  Desirably, the longitudinal dimension of the long grain 27a of silicon carbide is 10 to 50 mm, and the dimension perpendicular to the longitudinal direction is 1 to 3 mm. And if the dimension of a longitudinal direction shall be 10 mm or more, the contact probability of the long grain objects 27a and 27a adjacent to each other can be raised. Further, if the same dimension is set to 50 mm or less, the production of the long granules 27a is not so difficult, the production cost can be reduced, and the breakage of the long granules 27a at the time of filling the fistula 23 is also caused. It can be effectively prevented, that is, the long grain 27a having a length corresponding to the manufacturing cost can be reliably disposed in the fistula 23.

  Further, 1 to 3 mm, which is a dimension in a direction perpendicular to the longitudinal direction of the long-grained material 27a, is substantially the same as the particle size of a granular material such as sand generally used as the base material 27b of the filler 27. Therefore, the long particles 27 a are easily mixed uniformly without being unevenly distributed in the base material 27 b of the filler 27, and as a result, high thermal conductivity can be ensured over the entire area of the filler 27.

  Incidentally, according to the above-mentioned dimensional range, the minimum size of the long grain 27a is 10 mm × 1 mm. Therefore, it is possible to surely prevent the problem that the long particles 27a flow out of the filler 27 mixed with the ground water, which tends to occur when the particle size is fine powder of micron order, and the filler 27 has a high heat for a long time. Conductivity can be maintained.

<<< About the installation method of the underground heat exchanger 21 >>>
8A to 8F are explanatory diagrams of the installation method of the underground heat exchanger 21. FIG.
First, as shown in FIG. 8A, a hole 23 having a hole diameter of 100 to 200 mm and a depth of 30 to 150 m is excavated in the target ground G using an excavator such as a boring machine.

  Simultaneously or in parallel with this, the corrugated pipe 31 and the first hose member 41 are carried on-site in a state of being wound around the reels 31R and 41R, respectively. In addition, since the 2nd hose member 45 is short, it does not need to carry in in a winding state. Then, the corrugated tube 31 is slightly extended from the reel 31R, and the cap member 33 is screwed together with the helical corrugated shape on the outer peripheral surface of the tip of the corrugated tube 31 as a male screw, thereby sealing the tube end opening 31ed. If it does so, grout material 37 will be poured into the tip part of corrugated pipe 31, and the above-mentioned meshing crevice S1 of a screwing part will be filled up.

  Next, the corrugated pipe 31 is built in the fistula 23. That is, as shown in FIG. 8A, the feeding end of the reel 31R is arranged above the hole 23, and as shown in FIG. 8B, the corrugated pipe 31 is arranged such that the tip end portion of the corrugated pipe 31 becomes the lower end part. Are fed out from the reel 31 </ b> R, so that the corrugated pipe 31 is sequentially built into the fistula 23. During the erection, the grouting material 37 at the lower end of the corrugated pipe 31 functions as a weight, and the corrugated pipe 31 as a whole maintains a straight and stable erected posture. Then, when the lower end portion of the corrugated pipe 31 reaches the vicinity of the bottom of the hole 23, the feeding of the corrugated pipe 31 is stopped. Then, the corrugated tube 31 is cut to separate the corrugated tube 31 from the reel 31R, thereby forming the upper end portion 31b of the corrugated tube 31 (see FIG. 8C).

  If it does so, as shown to FIG. 8C, the filler 27 will be inject | poured into space SP23 between the hole 23 and the corrugated pipe | tube 31 using a funnel.

  However, as shown in the enlarged vertical sectional view of FIG. 9, the outer peripheral surface 31 c of the corrugated pipe 31 has a spiral waveform shape. Therefore, if the filling material 27 is simply dropped and filled from above, the valley portion of the spiral waveform shape and the space in the vicinity thereof become a shadow of the mountain portion, and it becomes difficult for the filling material 27 to turn there, That is, voids are generated. Such voids inhibit heat conduction from the ground G to the heat medium 26 in the corrugated pipe 31.

  Therefore, in order to crush such a gap, as shown in FIG. 8D, after filling the filler 27, a vibrator 81 is placed in the corrugated pipe 31 to vibrate the corrugated pipe 31, thereby filling the filler 27 around the gap 27. Are gradually dropped to fill the gap. Then, when the gap is filled, the filling height of the filler 27 is lowered accordingly, so that the amount of filler 27 is additionally charged into the fistula 23.

  However, the total length of the corrugated pipe 31 is several tens of meters to several hundreds of meters, and the total length of the vibrator 81a of the vibrator 81 is several tens of centimeters. Therefore, for example, when the vibrator 81a of the vibrator 81 is brought into contact with the inner peripheral surface of the upper end portion 31b of the corrugated pipe 31, the vibration is caused over the entire length of the corrugated pipe 31 that is several tens to several hundreds of meters. I can't tell you.

  Therefore, as shown in FIG. 8D, the vibrator 81 a is suspended in the corrugated pipe 31 by a hanger 81 b such as a wire, and the hanger 81 b is operated so that the vibrator 81 a extends over the entire length of the corrugated pipe 31. It moves up and down. As a result, the portion of the inner peripheral surface 31d of the corrugated tube 31 that vibrates due to the contact of the vibrator 81a is sequentially moved over the entire length of the corrugated tube 31 so that almost all the gaps are crushed.

  From the viewpoint of efficiently completing this filling operation in a short time, preferably, the position where the vibrator 81a is first brought into contact is the lower end portion of the corrugated pipe 31, and thereafter, this contact position is shifted upward. And good. This is because when the gap is filled, the amount of filler 27 corresponding to the gap falls from above, that is, instead of filling the gap, a new gap is formed above the gap. Therefore, there is no waste of work by squashing first from the lower gap.

  When the filler 27 is densely filled in the space SP23 between the stoma 23 and the corrugated pipe 31 in this way, the first hose member is disposed above the upper end portion 31b of the corrugated pipe 31 as shown in FIG. 8E. Forty-one reels 41 </ b> R are arranged, the first hose member 41 is fed out from the reel 41 </ b> R, and the first hose member 41 is inserted into the corrugated pipe 31. When the insertion is completed, as shown in FIG. 8F, the cap member 35 is screwed into the upper end portion 31b of the corrugated pipe 31 to seal the pipe end opening 31eu of the upper end portion 31b. At this time, the first hose member 41 and the second hose member 45 are passed through the two through holes 35h and 35h of the cap member 35, respectively.

=== Other Embodiments ===
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, The deformation | transformation as shown below is possible in the range which does not deviate from the summary.

  In the above-described embodiment, the vertical type underground heat exchanger 21 in which the flow direction of the heat medium 26 in the corrugated pipe 31 is set to the vertical direction is illustrated, but the invention is not limited to this, and a horizontal method may be used. That is, the tube axis C31 of the corrugated pipe 31 may be accommodated in a horizontal excavation hole while being horizontal, whereby the flow direction of the heat medium 26 in the corrugated pipe 31 may be horizontal. Needless to say, the material is backfilled with the filler 27 after being accommodated in the excavation hole.

  In the above-described embodiment, as shown in FIG. 3, the cap member 33 that is screwed into the lower end portion 31a of the corrugated pipe 31 is exemplified as having a female screw, that is, the cap member 33 is configured to remove the lower end portion 31a. Although the lower end portion 31a is sealed while covering, the present invention is not limited to this. For example, the relationship between the male screw and the female screw may be reversed. In other words, a helically wavy shape portion on the inner peripheral surface 31 d of the lower end portion 31 a of the corrugated pipe 31 may be used as a female screw, and a male screw that engages with this female screw may be provided on the outer peripheral surface of the cylindrical portion 33 a of the cap member 33.

1 building, 11 underground heat exchange system, 15 heat pump,
21 underground heat exchanger, 23 borehole (excavation hole), 23a hole wall,
26 heat medium, 27 filler, 27a long grain, 27b substrate,
31 corrugated pipe, 31a lower end (pipe end), 31b upper end,
31c outer peripheral surface, 31d inner peripheral surface, 31ed tube end opening, 31eu tube end opening,
31R reel, 33 cap member, 33a cylindrical portion, 33b substantially conical portion,
33c inner peripheral surface, 33f bottom, 35 cap member,
35c outer peripheral surface, 35h through hole, 37 grout material,
41 first hose member, 41e pipe end opening, 41R reel,
45 second hose member, 45e pipe end opening,
81 vibrator, 81a vibrator, 81b hanger,
G ground, S1 gap, h1 through hole, h2 through hole, SP23 space

Claims (6)

An underground heat exchanger that exchanges heat with the ground,
A flexible resin corrugated pipe disposed in the excavation hole of the ground;
A discharge port for discharging a heat medium into the corrugated tube;
A discharge port for discharging the heat medium exchanged with the ground from the corrugated pipe;
A filler filled between the excavation hole and the corrugated pipe,
The corrugated shape of the tube wall portion of the corrugated tube is formed in a spiral shape with the tube axis of the corrugated tube as the central axis,
One underground end of the corrugated tube is sealed with a cap member that is screwed with the corrugated portion at the end of the tube as a threaded portion. The underground heat exchanger according to claim 1,
The pipe end sealed with the cap member is filled with a cement-based material or a resin-based grout material so as to straddle the cap member and the pipe end. Medium heat exchanger. The underground heat exchanger according to claim 2,
The corrugated pipe is inserted along the vertical axis of the corrugated pipe into the borehole drilled in the vertical direction on the ground as the excavation hole,
A subterranean heat exchanger characterized in that a pipe end on the lower side in the vertical direction of the corrugated pipe is sealed by the cap member, and the grout material is filled in the pipe end. The underground heat exchanger according to any one of claims 1 to 3,
On the inner peripheral surface of the cap member, a female screw is formed which is screwed with the corrugated portion on the outer peripheral surface of the tube end as a male screw,
The cap member seals the tube end portion while covering the tube end portion from the outside. The underground heat exchanger according to any one of claims 1 to 4,
The filler filled between the excavation hole and the corrugated pipe contains a long particle made of at least one of silicon carbide, alumina, and blast furnace slag at a predetermined volume content. An underground heat exchanger characterized by that. The underground heat exchanger according to claim 5,
The longitudinal dimension of the long particles is 10 to 50 mm,
The underground heat exchanger characterized in that a dimension in a direction orthogonal to the longitudinal direction is 1 to 3 mm.