JP5786014B2 - Closed loop underground heat exchanger - Google Patents

Description

  The present invention relates to a closed-loop type underground heat heat exchange apparatus that uses groundwater as a heat medium on the heat source side (primary side) and performs heat exchange with the heat medium on the use side (secondary side). The present invention relates to a closed-loop underground heat exchange device that can perform efficient heat exchange with a small amount of water using a small well.

  As a form of use of geothermal heat, a heat exchange tube that circulates the heat medium is embedded in a heat exchange well provided in the ground, and a closed loop type that performs heat exchange, and pumped groundwater is used for heat exchange, Although it is divided roughly into two types of the open loop type which returns to the ground again after heat exchange, recently, a hybrid type underground heat heat exchange device combining both is also proposed.

  That is, as described in, for example, Patent Document 1, in a hybrid type underground heat exchanger, a casing (such as a slit) subjected to water permeation treatment along a heat exchange well formed in the ground from the ground surface ( For example, a perforated pipe is inserted, ground water is stored inside the casing, and a heat exchange tube is inserted therein to exchange heat with the ground water.

  According to this, since ground water of substantially constant temperature flows in the casing, stable heat exchange is performed between the heat exchange tube and the ground water. However, the following problems remain in this hybrid type underground heat exchanger.

  That is, in the conventional hybrid type underground heat exchanger, the space from the groundwater level surface to the ground surface inside the casing is hollow (that is, the air layer with the lowest thermal conductivity), so there is almost no heat exchange between them. It was not done.

  On the other hand, recently, a ground heat heat exchange device in which a heat exchange tube is embedded in advance in a foundation pile for construction and the foundation pile is used as a heat exchange well has been proposed in part. However, in this type of heat exchange well, since the outer periphery of the heat exchange tube is solidified by concrete, the heat exchange tube cannot be directly cooled with water, and thus the heat exchange efficiency is poor.

JP 2008-292030 A

  Then, the subject of this invention is providing the closed-loop type underground heat heat exchange apparatus which raised the heat exchange efficiency of the heat exchange tube more.

In order to achieve the above-described problems, the present invention provides a closed-loop type geothermal heat that uses geothermal heat that uses geothermal heat as a heat source and performs heat exchange between the geothermal heat and the heat medium on the use side. In the exchange device, a heat exchange well drilled in a vertical cylindrical shape from the ground surface through the underground water level line, a heat exchanger comprising a heat exchange tube housed in the heat exchange well, and the heat exchanger Circulation means for circulating the heat medium on the use side inside, a cylindrical casing is inserted in the inner peripheral surface of the heat exchange well, and at a position corresponding to the groundwater level line of the casing. A partition member for vertically partitioning the inside of the casing is provided, and a water-permeable hole through which ground water passes is provided below the partition member, and a predetermined filling is provided on the upper side with the partition member interposed. A filler layer filled with material and having water permeability is provided. And, in the heat exchanger wells, it is characterized in that the first water injection means for injecting water into the filler material layer is provided.

  Moreover, the aspect further provided with the 2nd water injection means which inject | pours water into the outer periphery of the said heat exchange well is also contained.

  Furthermore, a water-permeable layer having a diameter larger than the outer diameter of the heat exchange well is provided on the outer surface of the heat exchange well on the ground surface side of the heat exchange well, and the first water injection means is configured to perform the heat exchange. Water is poured simultaneously into the filler layer inside the well and the water permeable layer outside the heat exchange well.

Further, in the present invention , in a closed loop type geothermal heat exchange device using geothermal heat that uses geothermal heat as a heat source and performs heat exchange between the geothermal heat and the heat medium on the use side, A heat exchanging well excavated in a vertical cylindrical shape from the ground to the ground, a heat exchanger accommodated in the heat exchanging well, and a circulation means for circulating the heat medium on the use side in the heat exchanger The heat exchange well is a building pile material having the heat exchanger inside, and a water permeable layer is provided on the outer periphery of the heat exchange well, and heat exchange of the heat exchanger also includes closed-loop ground heat heat exchange apparatus aspect, characterized in that it comprises a water injection means for injecting water into the aquifer to enhance the efficiency.

According to the present invention, the entire heat exchange efficiency can be further increased by pouring water into the inside or outside of the heat exchange well, or both. Further, in the case of the pilings for construction with a heat exchanger inside you use as a heat exchange well, by performing the water injection as required to form a water-permeable layer on its outer periphery, always high heat exchange Efficiency can be obtained.

1 is a general view schematically showing the configuration of a closed-loop underground heat exchange device according to a first embodiment of the present invention. The whole figure which showed typically the composition of the closed loop type underground heat exchange device concerning a 2nd embodiment of the present invention. The whole figure which showed typically the composition of the closed loop type underground heat exchanger concerning a 3rd embodiment of the present invention. The whole figure which showed typically the composition of the closed loop type underground heat exchanger concerning a 4th embodiment of the present invention. The whole figure which showed typically the composition of the closed loop type underground heat exchanger concerning a 5th embodiment of the present invention.

  Next, each embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to this.

  As shown in FIG. 1, a closed-loop type underground heat exchanger 1A (hereinafter simply referred to as an underground heat exchanger 1A) according to the first embodiment is a cylinder excavated from a ground surface G almost vertically. The heat exchange well 2A and the heat exchange tube (heat exchanger) 3 arranged along the heat exchange well 2A are provided.

  The heat exchanging well 2A has a cylindrical shape drilled from the ground surface G substantially vertically, and in this embodiment, is excavated to penetrate the groundwater level line WL. The heat exchange well 2A is usually provided at a plurality of locations, but only one location is shown for convenience of explanation.

  A casing 21 is inserted along the inner peripheral surface of the heat exchange well 2A in the first embodiment. The casing 21 is made of a steel pipe having substantially the same diameter as the inner diameter of the heat exchange well 2 </ b> A, and the inside is partitioned vertically by a predetermined partition member (packer) 22. In the first embodiment, the casing 21 uses a so-called perforated tube in which a slit hole 211 is provided in part.

  The partition member 22 is a metal plate that is integrally fixed to the inner peripheral surface of the casing 21 by, for example, welding, and a part thereof is provided with an insertion hole 221 through which the heat exchange tube 3 is inserted. The partition member 22 is disposed at substantially the same position as the position corresponding to the groundwater level line WL of the formation where the heat exchange well 2A is excavated.

In this embodiment, the partition member 22 is made of a metal plate. However, the partition member 22 may have water permeability so that water poured into the upper filler layer 23 is allowed to escape through the partition member 22 to the lower water storage space. Good. As the partition member 22, in addition to a metal plate, a member provided with a water permeable hole such as a punching metal or a grating panel may be used. In that case, it is preferable to fill a rough filler between the partition member 22 and the filler 231 so that the filler 231 does not slide down from the water-permeable holes.

  A slit hole 211 is provided on the lower side of the casing 21 with the partition member 22 interposed therebetween. The slit holes 211 are vertically long holes opened along the axial direction of the casing 21, and many slit holes 211 are arranged at predetermined intervals along the circumferential direction of the casing 21. Groundwater that has exuded from the formation through the slit hole 211 is temporarily stored in the casing 21.

  In this embodiment, a straight slit hole 211 is formed in the casing 21. However, for example, a round hole may be used, or a mesh-like hole or a part thereof may be cut out to integrally attach a grating panel or the like. The specification may be arbitrarily changed as long as it is a water-permeable hole that can permeate groundwater while preventing collapse of the inner wall of the heat exchange well 2A.

  A filler layer 23 is formed on the upper side of the casing 21 with the partition member 22 interposed therebetween. The filler layer 23 is a water permeable layer having an appropriate water permeability by filling the filler 231 made of a relatively rough granular material such as gravel from the partition member 22 to almost the ground surface. The filler 231 can be arbitrarily selected according to the specifications as long as the filler layer 23 can have appropriate water permeability.

  The heat exchange tube 3 is a U-shaped tube in which a straight tube is bent in a U-shape, one side being the forward path side and the other being the return path side, and the bent tip is inserted toward the bottom of the heat exchange well 2A. Has been. A weight (not shown) is suspended from the folded portion at the bottom of the heat exchange tube 3, and the heat exchange tube 3 is always arranged vertically along the heat exchange well 2 by the weight.

  In this example, the heat exchange tube 3 includes one heat exchange tube 3 for one heat exchange well 2. For example, two U-shaped heat exchange tubes 3 are crossed in an X shape. May be inserted.

  Both the inlet side and the outlet side of the heat exchange tube 3 are connected to the underground heat exchange unit HP. In the present invention, the underground heat heat exchange unit HP has a basic form of a grown loop type in which a heat medium flowing in the heat exchange tube 3 circulates between the underground heat heat exchange unit HP and the heat exchange well 2A. However, as a typical example, hot water supply using a heat cycle, an air conditioner, or the like is used as the use side heat source.

  The heat exchange tube 3 is preferably provided with a spacer (not shown) for supporting the forward path side and the return path side of the heat exchange tube 3 at a predetermined interval.

The heat exchange well 2 </ b> A is provided with first water injection means 4 for injecting water into the filler layer 23 to increase the heat exchange efficiency of the heat exchange tube 3. The first water injection means 4 includes a water storage tank 41 for storing water, a first water supply pipe 42 for sending water from the water storage tank 41 to the heat exchange well 2A, and a first water injection pipe installed in the filler layer 23. 43.

  The water storage tank 41 is a tank capable of storing a predetermined amount of water therein, and is installed on the ground in this embodiment. The water storage tank 41 may be installed underground. The water storage tank 41 can be replaced with, for example, a pond or a river. The water stored in the tank may be natural water such as rain water, pond, river, etc. in addition to clean water and middle water.

  The first water supply pipe 42 is a general water supply pipe such as a PVC pipe, for example, and is drawn out from the water storage tank 41 into the ground, and a part of the first water supply pipe 42 is controlled to be opened and closed by a control means (not shown). A valve 421 is provided.

  The 1st water injection pipe 43 consists of a pipe formed cyclically | annularly according to the shape of 2 A of heat exchange wells, and the water injection hole which is not shown in figure is provided at predetermined intervals. In this embodiment, the 1st water injection pipe 43 is each an independent annular pipe, Comprising: They are provided in three places at predetermined intervals along an axial direction.

A first water supply pipe 42 is connected to each first water injection pipe 43 through a predetermined joint, and water sent from the water storage tank 41 through the water supply pipe 42 to the first water injection pipe 43 is a filler layer. 23 is poured into water. The filler layer 23 is set a temperature sensor 24 is embedded, the control unit based on the temperature information by the temperature sensor 24 controls the first on-off valve 421 described above.

In the first embodiment, the first water injection pipe 43 is composed of three annular pipes arranged at equal intervals and connected to the first water supply pipe 42 via a joint. For example, the first water supply pipe 42 is provided. It is also possible to insert only water into the filler layer 23 and provide water injection holes on the outer periphery thereof. Furthermore, a water injection pipe formed in a spiral shape from the bottom to the top of the filler layer 23 may be used.

  Next, with reference to FIG. 2, the underground heat exchanger 1B which concerns on 2nd Embodiment of this invention is demonstrated. In addition, the same referential mark was attached | subjected to the location considered to be the same as or the same as the underground heat exchanger 1A of the said 1st Embodiment. This underground heat exchanger 1B includes a heat exchange well 2B having a configuration substantially the same as the heat exchange well 2A of the first embodiment.

  The underground heat exchanger 1B is provided with a first water injection means 4 for injecting water inside the heat exchange well 2B and a second water injection means 5 for injecting water outside the heat exchange well 2B. Yes. The 2nd water injection means 5 is provided with the 2nd water supply pipe 51 which sends the water from the water storage tank 41 in the ground, and the 2nd water injection pipe 52 arrange | positioned along the outer periphery of the heat exchange well 2B.

  In this modification, the second water supply pipe 51 is a branch pipe branched from a part of the first water supply pipe 42, and a second opening / closing valve 511 that is controlled to be opened and closed by the control unit is provided in a part thereof. ing. The second opening / closing valve 511 is also controlled by the control means based on the temperature data of the temperature sensor 24.

  The 2nd water injection pipe 52 consists of a pipe formed in the cyclic | annular form larger diameter than the outer diameter of the heat exchange well 2B, and many water injection holes which are not shown in figure are provided with the predetermined space | interval. In this modification, the second water injection pipes 52 are provided at three predetermined intervals along the water permeable layer 23 of the heat exchange well 2B.

  According to this, the heat exchange efficiency in the water permeable layer 23 can be further improved by injecting water into both the inside and outside of the heat exchange well 2B. Also in the second embodiment, the second water injection pipe 52 is not limited to an annular shape, and may be a straight pipe inserted vertically from the ground or a spiral pipe. Furthermore, water may be sprayed from the ground surface without being buried in the ground.

  Next, with reference to FIG. 3, 1 C of geothermal heat exchangers which concern on 3rd Embodiment of this invention are demonstrated. This underground heat exchange device 1C includes a heat exchange well 2C excavated from the ground surface G along the vertical direction so as to be deeper than the groundwater level line WL.

  Inside the heat exchange well 2C, a first filler layer 23a filled with a predetermined filler from the bottom of the heat exchange well 2C to a height reaching the groundwater level line WL, and from the groundwater level line WL to near the ground surface It has a two-layer filling structure having a second filler layer 23b filled with a predetermined filler, and a heat exchange tube 3 is disposed therein.

  In the third embodiment, the heat exchanging well 2C does not have the casing 21 described in the first embodiment, and the excavation surface is exposed. There is a risk that. Therefore, the inner wall is prevented from collapsing by filling the heat exchange well 2C with a filler.

  The first filler layer 23a is made of a coarse granular material in which many voids are formed by filling, for example, pebbles or crushed stones, and is filled up to a position substantially the same as or slightly above the groundwater level line WL. . According to this, the groundwater oozed out from the surface of the heat exchange well 2C is accumulated in the heat exchange well 2C.

  The same partition member 22 as in the first embodiment is provided on the upper part of the first filler layer 23a, and the second filler layer 23b is formed on the upper part thereof. The second filler layer 23b is the same as the filler layer 23 of the first embodiment described above, and is filled with a relatively rough granular material such as gravel from the partition member 22 to almost the ground surface to provide an appropriate water permeability. It is a permeable layer provided with.

  The second filler layer 23b of the heat exchange well 2C is provided with the first water injection means 4, and the heat exchange efficiency of the heat exchange tube 3 positioned above the groundwater level line WL is increased by water injection. Can do.

In the heat exchange device 1C of the third embodiment, the first water injection means 4 injects water only into the heat exchange well 2C, but the second water injection means 5 is further provided as in the second embodiment. Alternatively, water may be poured into both the inside and outside of the heat exchange well 2C.

  Next, with reference to FIG. 4, a geothermal heat exchange device 1D according to a fourth embodiment of the present invention will be described. The underground heat heat exchange device 1D according to the fourth embodiment has a heat exchange well 2D excavated from the ground surface G along the vertical direction, and is connected to the underground heat heat exchange unit HP in the inside thereof. A heat exchange tube 3 is provided.

  In the fourth embodiment, the heat exchanging well 2D is suitably provided for a relatively dry formation such as, for example, under a building, under a paved road surface, or at a position shallower than the groundwater level line WL.

  A water permeable layer 25 having a diameter larger than the outer diameter of the heat exchange well 2D is provided on the upper side of the heat exchange well 2D. The water permeable layer 25 is an enlarged diameter portion formed coaxially with respect to the outer periphery of the heat exchange well 2D, and is formed integrally with the heat exchange well 2D.

  Both the heat exchanging well 2D and the water permeable layer 25 have exposed excavation surfaces, and a filler layer 23 filled with a filler is formed inside. The filler layer 23 is the same as the filler layer 23 of the first embodiment described above, and is filled with a relatively rough granular material such as gravel from the bottom of the heat exchange well 2D to almost the ground surface to provide an appropriate water permeability. It is a water permeable layer with properties.

  A first water injection pipe 43 of the first water injection means 4 is embedded in the water permeable layer 25. The first water injection pipe 43 is formed in an annular shape along the inner peripheral surface of the water permeable layer 25. According to this, a part of the water poured into the permeable layer 25 from the first water injection pipe 43 flows into the heat exchange well 2D, and the heat exchange tube 3 can be directly cooled. Moreover, a part of water can cool the whole heat exchange well 2D indirectly from the outer side by penetrating into the outer peripheral surface of the heat exchange well 2D from the bottom surface 251 of the water permeable layer 25.

  In the fourth embodiment, only one heat exchange well 2D is drawn in FIG. 4, but a plurality of heat exchange wells 2D may be provided under one water permeable layer 25, for example. According to this, by pouring water into one water-permeable layer 25, water can be poured simultaneously into the inside of the plurality of heat exchange wells 2D and the outer periphery thereof. Such an embodiment is also included in the present invention.

  Next, with reference to FIG. 5, the underground heat exchanger 1E which concerns on 5th Embodiment of this invention is demonstrated. This underground heat exchange device 1E includes a heat exchange well 2E formed from the ground surface G along the vertical direction.

  In the fifth embodiment, the heat exchange well 2E is made of a pile material for construction. That is, the heat exchanging well 2E is formed by driving a pile material having the heat exchanging tube 3 and the thermometer 24 therein to the strong support layer KL in the ground.

  In this fifth embodiment, the heat exchanging well 2E is made of a concrete pile material (a so-called concrete pile (also referred to as a PHC pile)) prepared in advance outside the site. For example, a cast-in-place pile formed integrally with the heat exchange tube 3 and the thermometer 24 by providing a drilling hole up to the support layer KL in the vertical direction at the construction site and pouring concrete there. Furthermore, a steel pipe pile without holes may be used.

  The heat exchange well 2E (pile material) does not have water permeability because the inside is filled with concrete. Therefore, in the underground heat heat exchange device 1E, a water permeable layer 26 for cooling the outer periphery of the heat exchange well 2E is provided on the outer periphery of the heat exchange well 2E.

  The water permeable layer 26 excavates the ground surface G and spreads relatively rough granular materials such as gravel on the ground surface G to have water permeability. In this 5th Embodiment, the water-permeable layer 26 is provided uniformly in the whole laying ground of the heat exchange well 2E (pile material), and many heat exchange wells 2E (pile material) are installed there at equal intervals. ing.

  The water permeable layer 26 is provided with third water injection means 6 for injecting water into the water permeable layer 26. The 3rd water injection means 6 is comprised from the water injection tank 61, the 3rd water supply pipe 62, and the 3rd water injection pipe 63 similarly to the 1st and 2nd water injection means 4 and 5 which were mentioned above.

  According to this, by injecting water into the water permeable layer 26 via the third water injection means 6, the outer periphery of the heat exchange well 2E (pile material) arranged under the building is always in a water-rich environment, The outer periphery of the exchange well 2E can be cooled to further increase the heat exchange efficiency.

  As explained above, according to the heat exchangers 1A to 1E in each place according to the first to fifth embodiments of the present invention, water is actively supplied to the inside and / or the outside of each heat exchange well 2A to 2E. By injecting water, heat exchange efficiency can be further improved by creating a water-rich environment around the heat exchange wells 2A to 2E even in dry formations such as above the groundwater level WL and under the building. Can do.

1A-1E Closed-loop type underground heat exchanger 2A-2E Heat exchange well 21 Perforated pipe 211 Slit 22 Partition member (packer)
23 Filling material layer 24 Thermometer (temperature sensor)
25, 26 Water permeable layer 3 Heat exchange tube 4 First water injection means 41 Water storage tank 42 Water supply pipe 43 Water injection pipe 5 Water injection pipe 51 Second water supply pipe 52 Second water injection pipe 6 Third water injection means 61 Water storage tank 62 Water supply pipe 63 Injection pipe HP Ground heat exchange unit

Claims (4)

In a closed-loop type geothermal heat exchange device using geothermal heat that uses geothermal heat as a heat source and performs geothermal heat exchange between the geothermal heat and the heat medium on the use side,
A heat exchange well drilled from the surface of the ground through the underground water level line into a vertical cylinder, a heat exchanger comprising a heat exchange tube housed in the heat exchange well, and the use in the heat exchanger Circulation means for circulating the heat medium on the side,
A cylindrical casing is inserted through the inner peripheral surface of the heat exchange well, and a partition member for vertically partitioning the inside of the casing is provided at a position corresponding to the groundwater level line of the casing. A water-permeable hole through which groundwater permeates is provided on the lower side across the member, and a filler layer having water permeability is provided on the upper side with the partition member interposed therebetween and having water permeability, A closed-loop type underground heat exchange device, wherein the heat exchange well is provided with first water injection means for injecting water into the filler layer.   The closed-loop type underground heat heat exchange device according to claim 1, further comprising second water injection means for injecting water into the outer peripheral side of the heat exchange well.   On the ground surface side of the heat exchange well, a water permeable layer having a diameter larger than the outer diameter of the heat exchange well is provided around the heat exchange well, and the first water injection means The closed-loop type underground heat heat exchange device according to claim 1, wherein water is poured simultaneously into the filler layer and the water permeable layer outside the heat exchange well. In a closed-loop type geothermal heat exchange device using geothermal heat that uses geothermal heat as a heat source and performs geothermal heat exchange between the geothermal heat and the heat medium on the use side,
A heat exchanging well excavated in a vertical cylindrical shape from the ground surface to the ground, a heat exchanger housed in the heat exchanging well, and a circulation means for circulating the heat medium on the use side in the heat exchanger And
The heat exchange well is a building pile material having the heat exchanger therein, and a water permeable layer is provided on the outer periphery of the heat exchange well to increase the heat exchange efficiency of the heat exchanger. closed-loop ground heat heat exchanger device characterized in that it comprises a water injection means for injecting water into the aquifer.

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