JP4990593B2 - Underground heat exchanger buried structure - Google Patents

Description

  The present invention relates to a buried structure of a ground heat exchanger that is buried in the ground and exchanges heat with the ground.

The depth in the ground (for example, a depth of 5 m or more) has a substantially constant temperature throughout the year (for example, 15 ° C.), and has a property that it is colder in summer and warmer than winter. An underground heat exchanger embedded in the ground is known to collect heat from the ground using this property or to dissipate heat to the ground. The underground heat exchanger is connected to a load device such as a heat pump, an air conditioner, or a snow melting device, and a heat medium such as air, water, or antifreeze is circulated between the load devices. The earth heat is used by being taken out.
Conventionally, as an underground heat exchanger, for example, a vertical hole having a diameter larger than the outer diameter of the heat exchanger is drilled, and a heat exchanger is inserted into the vertical hole. An antifreeze circulating geothermal heat utilization device filled with silica sand between the exchanger and “Patent Document 2”, “an outer cylinder inserted into a well drilled in the ground and sealed at its lower end, A flow hole through which a fluid flows is provided in the lower side wall portion and the inner cylinder is inserted between the well and the outer cylinder, and the outer cylinder is grounded. An underground heat exchanger provided with a grout kneaded with a highly heat-conductive material such as silica sand to be fixed on the ground is known.
As described above, the underground heat exchanger is filled with a grout kneaded with sand such as silica sand and good heat conductive material such as silica sand between the vertical hole drilled in the ground and the heat exchanger. By doing so, the heat exchanger can be fixed to the ground, and heat conduction between the heat exchanger and the ground can be realized.
JP 2003-307353 A JP 2003-130471 A

However, the above conventional techniques have the following problems.
(1) In general, geothermal heat exchangers have a limit to the amount of geothermal heat that can be used using a single vertical hole excavated in the ground, and experience has shown that geothermal heat can be collected by collecting heat from the ground and dissipating it into the ground. The available range is from the outer periphery of the vertical hole to the range of 0.4 m in diameter, and it is known that it hardly depends on the surface area (heat transfer area) of the heat exchanger. Therefore, in the underground heat exchanger as disclosed in (Patent Document 1) and (Patent Document 2), in order to increase the amount of heat exchange, the vertical holes to be excavated are deepened or the number of vertical holes is increased. In this case, the construction man-hours increase, the construction period becomes longer, and the construction cost also increases.
(2) Since the above phenomenon hardly depends on the surface area (heat transfer area) of the heat exchanger, the main component of the sand filled in the vertical holes and the silica sand kneaded into the grout is silicon dioxide, It is presumed that the thermal conductivity (theoretical value) of silicon dioxide is related to only 2 W / m · K. For this reason, even if it changes the structure of a heat exchanger, such as increasing the surface area (heat transfer area) of a heat exchanger, the amount of heat exchange cannot be enlarged, but the subject that there is a certain limit in the amount of geothermal heat that can be used effectively Had.

  The present invention solves the above-mentioned conventional problems, dramatically improves the heat exchange rate between the underground heat exchanger and the ground, and can use the ground heat by collecting heat from the ground and radiating heat to the ground. Because it can expand the range of the geothermal heat, it is possible to dramatically increase the use efficiency of geothermal heat, and can secure the necessary heat exchange amount without deepening the pits or increasing the number of pits, An object of the present invention is to provide a buried structure of an underground heat exchanger excellent in workability capable of preventing an increase in construction period and construction cost.

In order to solve the above conventional problems, the underground heat exchanger embedding structure of the present invention has the following configuration.
The underground heat exchanger embedding structure according to claim 1 of the present invention includes a pothole formed in the ground, a ground heat exchanger disposed in the pothole, and the earth filled in the pothole and flowing in the ground. A ground heat exchanger that includes a granular filler that permeates between particles and promotes heat exchange between the ground heat exchanger and the ground by the ground water , The filler contains silicon particles having a purity of 90% or more, the silicon particles are classified into a plurality of types for each particle size range, and the plurality of classified silicon particles are mixed. Yes.
With this configuration, the following effects can be obtained.
(1) Since the filler contains silicon particles with a purity of 90% or more and the thermal conductivity of silicon is 148 W / m · K, the heat exchange rate between the underground heat exchanger and the ground is dramatically improved. The range of the earth where geothermal heat can be used can be expanded by collecting heat from the ground and radiating heat to the ground.
(2) For this reason, since the necessary heat exchange amount can be ensured without deepening the pits or increasing the number of pits, it is possible to prevent the construction period from increasing and the construction cost from increasing.
(3) The filler is preferably composed of silicon particles because of its high thermal conductivity, but in addition to silicon particles, it is not a hydraulic material such as concrete or mortar, but a granular filler such as earth or sand, earth or sand. By using this, groundwater flowing in the ground permeates between the particles of the filler in the pit, and the groundwater promotes heat exchange between the underground heat exchanger and the ground.
(4) Since the silicon particles are classified into a plurality of types for each particle size range, and the plurality of classified silicon particles are mixed, the silicon particles filled in the potholes can be filled at a high density. And the amount of heat exchange can be improved.

  Here, examples of the pothole include a pothole formed by boring in the ground, a pothole formed by burying a pile provided with screw-like fins at the tip, and having a diameter of 10 to 25 cm, What was formed in the depth of 10-200 m can be used. After placing the underground heat exchanger in the pothole, the pothole is backfilled with filling material to or near the ground.

As an underground heat exchanger, well-known things, such as a double pipe system, a U tube system, and a WU tube system, can be used.
The double pipe system is composed of a double pipe consisting of an inner pipe and an outer pipe, and a heat medium flowing down the outer pipe is returned from the lowest end through the inner pipe. A system in which the heat medium circulates from the inner pipe through the outer pipe is also possible. The U tube system is configured by connecting two straight pipes with a U-shaped tube, and heat is exchanged from one end of the tube to the other end through a heat medium. The WU tube system is configured by arranging two sets of U-shaped tubes in a cross shape, and increases the heat exchange amount of the U tube system.
Further, at least one U-tube type straight pipe or a double-pipe type outer pipe replaced with a helical channel formed in a spiral shape can be used. The underground heat exchanger provided with the spiral channel has a length in the spiral axis direction of 1/3 to 1 in order to obtain a heat transfer area equivalent to that of the underground heat exchanger having a long straight pipe portion. / 20 can be shortened, so that the depth of the hole can be reduced to about 1/3 to 1/20 of the conventional depth, and the excavation cost can be greatly reduced. It is excellent in that it can be backfilled with a small amount of filler and is excellent in backfilling workability.

  As the filler, a material containing silicon grains having a purity of 90% or more, preferably 95% or more is used. As the purity of the silicon particles becomes lower than 95%, the thermal conductivity of the silicon particles tends to decrease. When the purity is lower than 90%, this tendency becomes remarkable, which is not preferable.

As the particle size of the silicon particles, those having an average particle size of 0.01 to 40 mm can be appropriately selected and used. When the average particle size of the silicon particles is smaller than 0.01 mm, the packing density of the silicon particles filled in the pits does not increase, and the heat exchange amount decreases because the heat is transferred through a large number of silicon particles. If it becomes large, the fluidity when filling the pothole will be poor, so the filling property will be poor and the workability will be poor, and the contact area with the underground heat exchanger will be reduced and the amount of heat exchange will be reduced. .
In a place where underground water is flowing down, it is preferable that at least the silicon particles filling the groundwater layer have a particle size that does not hinder the flow of groundwater. This is because the groundwater flowing through the groundwater layer in the ground permeates between the filler particles in the pit and promotes heat exchange between the underground heat exchanger and the ground.

The filler is preferably composed of silicon particles because of its high thermal conductivity, but in addition to silicon particles, it is not a hydraulic material such as concrete or mortar, but a granular filler such as earth, sand or sand. Therefore, the groundwater flowing in the ground permeates between the particles of the filler in the pothole, and the groundwater promotes heat exchange between the underground heat exchanger and the ground, which is preferable.
As the particle size range of the silicon particles to be classified, any particle can be used without particular limitation as long as it is adjusted so that the inside of the pit can be filled with high density. For example, the fine particles having an average particle size of 0.1 to 5 mm and the coarse particles having an average particle size of 10 to 30 mm are classified and mixed with the fine particles and the coarse particles. Is excellent in heat conduction performance as compared with those filled only with fine particles and those filled only with coarse particles, and is preferably used.

The invention according to claim 2 of the present invention is the buried structure of the underground heat exchanger according to claim 1, wherein the silicon particles are waste silicon particles generated in the process of manufacturing a semiconductor element material, or It has the structure which is the crushing waste of a silicon wafer.
With this configuration, in addition to the operation obtained in the first aspect, the following operation can be obtained.
(1) Since silicon particles are waste silicon particles generated during the manufacturing process of semiconductor element materials or silicon wafer crushed debris, the thermal conductivity is high due to the high purity of silicon, and wastes are used effectively. Can do.

  Here, as the discarded silicon particles, silicon particles having a purity of about 90 to 99% generated when silicon is produced by reducing silicon dioxide in the manufacturing process of the semiconductor element material are used. As the silicon wafer crushing waste, defective silicon wafer crushing waste or the like is used. These silicon particles can be used as they are without being pulverized, or can be appropriately pulverized to have a predetermined particle size.

The invention according to claim 3 of the present invention is the underground heat exchanger embedding structure according to claim 1 or 2, wherein the underground heat exchanger is at least partially formed in a spiral shape. A helical flow path through which the heat medium flows, a helical shaft space formed around the helical axis inside the helical flow path, a connecting member connected to the lower end of the helical flow path, and a straight tube shape An underground heat transfer medium channel formed and connected to the lower end of the spiral channel via the connecting member and disposed in the spiral axis space substantially parallel to the spiral axis direction of the spiral channel; A gap holding member disposed at intervals along the underground heat medium flow path, and the gap holding member is formed in an annular shape, and a base portion into which the underground heat medium flow path is inserted , configuration in which the arm portion extending to the base, and a fitting portion in which the spiral flow path is formed in the arm portion end has been fitted, the It has.
With this configuration, in addition to the operation obtained in the first or second aspect, the following operation can be obtained.
(1) Since the heat medium has a spiral flow path through which the heat medium flows, in order to obtain a heat transfer area equivalent to the underground heat exchanger having a long straight pipe portion, the length in the direction of the spiral axis is set. It can be shortened to about 1/3 to 1/20. Therefore, the depth of the pothole in which the underground heat exchanger is disposed can be about 1/3 to 1/20 of the depth of the pothole in the case of the conventional straight tubular underground heat exchanger, The excavation cost can be significantly reduced, and the excavation amount is small, so excavation workability and workability are excellent.
(2) Since the pothole for embedding the underground heat exchanger can be made shallow, the pothole can be backfilled with a small amount of filler, and the backfilling workability is excellent.
(3) Since the space holding member for holding the space between the spiral channels is provided, the spiral channel 3 is not deformed by the pressure of the filler when being backfilled, and excessive stress is locally generated. It is difficult to work and difficult to pitch, so it has excellent durability.
(4) Since the gap holding member is provided, the gap between the spiral channels is prevented from being narrowed or widened by the pressure of the filler, and the spiral channel is placed in the pothole. It is possible to arrange them evenly at intervals, and it is difficult to generate heat exchange spots, and high heat exchange efficiency can be maintained.
(5) Since the interval of the spiral channel can be maintained by the interval holding member, the spiral channel can be formed by a spiral tube made of a synthetic resin and formed in a coil shape, which is remarkably versatile. Excellent.
(6) When the spiral flow path 3 is formed by a spiral tube made of a synthetic resin and formed in a coil shape, since it expands and contracts in the direction of the spiral axis, it is in a contracted state when transported to the construction site. It is compact and has excellent transportability, and it can be easily installed by fixing it with a spacing member while stretching at the construction site.

Here, the interval holding member disposed and fixed in the underground heat medium flow channel can be appropriately selected for the interval and quantity so that the interval of the spiral flow channel can be maintained.

As described above, according to the underground heat exchanger and its embedded structure of the present invention, the following advantageous effects can be obtained.
According to the invention of claim 1,
(1) Since the filler contains silicon grains having a purity of 90% or more, the heat exchange rate between the underground heat exchanger and the ground is dramatically improved, and heat is collected from the ground and into the ground. It is possible to provide a buried structure of the underground heat exchanger that can expand the range of the earth where heat can be used by heat radiation and can dramatically increase the use efficiency of the heat.
(2) Since the necessary amount of heat exchange can be secured without deepening the pits or increasing the number of pits, it has excellent workability that can prevent the construction period from increasing and construction costs from increasing. A buried structure of the underground heat exchanger can be provided.
(3) The filler is preferably composed of silicon particles because of its high thermal conductivity, but in addition to silicon particles, it is not a hydraulic material such as concrete or mortar, but a granular filler such as earth or sand, earth or sand. By using this, groundwater flowing in the ground permeates between the particles of the filler in the pit, and the groundwater promotes heat exchange between the underground heat exchanger and the ground.
(4) Since the silicon particles are classified into a plurality of types for each particle size range, and the plurality of classified silicon particles are mixed, the silicon particles filled in the potholes can be closely packed, A buried structure of the underground heat exchanger that can improve the heat exchange amount can be provided.

According to invention of Claim 2, in addition to the effect of Claim 1,
(1) Since the silicon grains are waste silicon grains generated during the manufacturing process of the semiconductor element material or silicon wafer crushed debris, the thermal conductivity is high due to high purity, and the waste can be effectively utilized. It is possible to provide a buried structure for underground heat exchangers with excellent resource saving.

According to invention of Claim 3, in addition to the effect of Claim 1 or 2,
(1) Since the heat medium has a spiral flow path through which the heat medium flows, in order to obtain a heat transfer area equivalent to the underground heat exchanger having a long straight pipe portion, the length in the direction of the spiral axis is set. It can be shortened to about 1/3 to 1/20. Therefore, the depth of the pothole in which the underground heat exchanger is disposed can be about 1/3 to 1/20 of the depth of the pothole in the case of the conventional straight tubular underground heat exchanger, The excavation cost can be significantly reduced, and the excavation amount is small, so excavation workability and workability are excellent.
(2) Since the pothole for embedding the underground heat exchanger can be made shallow, the pothole can be backfilled with a small amount of filler, and the backfilling workability is excellent.
(3) Since the space holding member for holding the space between the spiral channels is provided, the spiral channel 3 is not deformed by the pressure of the filler when being backfilled, and excessive stress is locally generated. It is difficult to work and difficult to pitch, so it has excellent durability.
(4) Since the gap holding member is provided, the gap between the spiral channels is prevented from being narrowed or widened by the pressure of the filler, and the spiral channel is placed in the pothole. It is possible to arrange them evenly at intervals, and it is difficult to generate heat exchange spots, and high heat exchange efficiency can be maintained.
(5) Since the interval of the spiral channel can be maintained by the interval holding member, the spiral channel can be formed by a spiral tube made of a synthetic resin and formed in a coil shape, which is remarkably versatile. Excellent.
(6) When the spiral flow path 3 is formed by a spiral tube made of a synthetic resin and formed in a coil shape, since it expands and contracts in the direction of the spiral axis, it is in a contracted state when transported to the construction site. It is compact and has excellent transportability, and it can be easily installed by fixing it with a spacing member while stretching at the construction site.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram showing a buried structure of the underground heat exchanger in the first embodiment, and FIG. 2 is a perspective view of the underground heat exchanger in the first embodiment.
In FIG. 1, 1 is an underground heat exchanger embedding structure according to Embodiment 1 of the present invention, 100 is the ground, 101 is embedded in the ground 100 while rotating a pile provided with boring and screw-like fins at the tip. A pothole 102 formed by the above method is a filler containing silicon particles with a purity of 90% or more filled in the pothole 101.
2 is an underground heat exchanger disposed in the pothole 101, 3 is made of a synthetic resin such as polypropylene, polybutene, and polyamide, and is made of a metal such as titanium, and at least a part thereof is formed in a spiral shape with air, water, A spiral flow path through which a heat medium such as antifreeze liquid flows, 4 is a spiral axis space formed around the spiral axis inside (inside the spiral) of the spiral flow path 3, and 5 is connected to the lower end of the spiral flow path 3. A connecting member 6 made of an elbow pipe, 6 is formed in a straight tube shape made of a synthetic resin such as polypropylene, polybutene, polyamide, etc., stainless steel, titanium or the like, and is connected to the lower end of the spiral flow path 3 via the connecting member 5. The underground heat medium flow path 7 connected and disposed in the helical axis space 4 substantially parallel to the direction of the helical axis of the helical flow path 3, 7 is spaced along the underground heat medium flow path 6. The disposed spacing holding member 8 is formed in an annular shape, and the underground heat medium flow path 6 is inserted therein. The base of the spacing members 7, 9 arm portion extending to the base 8, 10 is a fitting portion with a helical flow path 3 is formed on the end portion of the arm portion 9 is fitted.

An example of the construction method will be described below with respect to the buried structure of the underground heat exchanger according to Embodiment 1 of the present invention configured as described above.
First, a pothole 101 having a predetermined diameter (200 mm in the present embodiment) is formed in the ground 100 with a depth that allows embedding while leaving the tip of the underground heat exchanger 2.
A spiral flow path 3, a ground heat medium flow path 6, a connecting member 5, and a gap holding member 7 are prepared, and a base 8 of the gap holding member 7 is disposed in the ground heat medium flow path 6 at an appropriate interval. Fix it. Next, the underground heat medium flow path 6 is inserted inside the spiral flow path 3, the connecting member 5 is attached to the lower end thereof, and then the lower end of the spiral flow path 3 is connected to the connecting member 5. The helical flow path 3 is fitted into the fitting portion 10 of the spacing member 7 disposed and fixed in the underground heat medium flow path 6, and inserted into the pothole 101 from the lower end of the underground heat medium flow path 6. The underground heat medium flow path 6 and the spiral flow path 3 are disposed over the entire length of 101.
Finally, the filler 102 made of silicon particles having a purity of 90% or more around the underground heat medium flow path 6 and the helical flow path 3 of the underground heat exchanger 2 disposed in the pothole 101, or the purity The filling material 102 containing earth and sand in addition to 90% or more of silicon grains is filled to the ground or near the ground, and the pothole 101 is refilled.

As described above, the underground heat exchanger 2 according to the first embodiment disposed in the ground is configured such that the upper ends of the spiral flow path 3 and the underground heat transfer medium path 6 are connected to a heat pump, an air conditioner, a snow melting apparatus, or the like. A heat medium that is connected to a load device (not shown) and that exchanges heat or cold heat with the load device flows from the upper end to the lower end of the spiral flow path 3 and exchanges heat with the ground 100 to exchange heat. Is circulated from the upper end of the underground heat medium flow path 6 to the load device.
Note that the direction in which the heat medium flows is not limited to this, and conversely, the heat medium is introduced into the underground heat exchanger 2 from the upper end of the underground heat medium flow path 6, and the spiral flow path 3. You may make it take out from the upper end of this, and let it flow to a load apparatus. In this case, the same effect can be obtained.

According to the buried structure of the underground heat exchanger according to Embodiment 1 of the present invention configured as described above, the following operation is obtained.
(1) Since the filler 102 contains silicon particles having a purity of 90% or more and the thermal conductivity of silicon is 148 W / m · K, the heat exchange rate between the underground heat exchanger 2 and the ground 100 is dramatically improved. The range of the ground 100 where the geothermal heat can be used can be expanded by heat collection from the ground and heat radiation to the ground.
(2) For this reason, since a necessary heat exchange amount can be ensured without deepening the pit hole 100 or increasing the number of pit holes 100, it is possible to prevent the construction period from increasing and the construction cost from increasing. .

Moreover, according to the underground heat exchanger 2 in Embodiment 1 of this invention as mentioned above, the following effects are obtained.
(1) Since the heating medium is provided with the spiral flow path 3, the length in the direction of the spiral axis is obtained in order to obtain a heat transfer area equivalent to that of the underground heat exchanger having a long straight pipe portion. Can be shortened to about 1/3 to 1/20. Therefore, the depth of the pothole 101 in which the underground heat exchanger 2 is disposed can be set to about 1/3 to 1/20 of the depth of the pothole in the case of a conventional straight tubular underground heat exchanger. The excavation cost of the hole 101 can be greatly reduced, and the excavation workability is excellent as well as the excavation workability is excellent because the excavation amount is small.
(2) Since the pothole 101 for embedding the underground heat exchanger 2 can be made shallow, the pothole 101 can be backfilled with a small amount of filler 102, and the backfilling workability is excellent.
(3) Since the gap holding member 7 that holds the gap of the spiral flow path 3 is provided, the spiral flow path 3 is not deformed by the pressure of the filler 102 when being backfilled, and is locally excessive. It is excellent in durability because it does not work easily and does not cause pitting.
(4) Further, since the interval holding member 7 is provided, it is possible to prevent the interval between the spiral channels 3 from being narrowed or widened due to the pressure of the filler 102, and the spiral channel in the pit 101. 3 can be evenly arranged at intervals of the interval holding member 7, and heat exchange spots hardly occur, and high heat exchange efficiency can be maintained.
(5) Since the interval of the spiral flow path 3 can be held by the interval holding member 7, the spiral flow path 3 can be formed by a spiral tube made of synthetic resin and formed in a coil shape. Remarkably excellent in properties.
(6) When the spiral flow path 3 is formed by a spiral tube made of a synthetic resin and formed in a coil shape, since it expands and contracts in the direction of the spiral axis, it is in a contracted state when transported to the construction site. It is compact and has excellent transportability, and can be easily fixed by being fixed by the spacing member 7 while being stretched at the construction site, so that it is excellent in workability.

  In addition, the space | interval holding member 7 arrange | positioned and fixed to the underground heat medium flow path 6 can select the space | interval and quantity suitably so that the space | interval of the helical flow path 3 can be hold | maintained.

Here, in the present embodiment, the case where the spiral flow path 3 of the underground heat exchanger 2 is disposed over the entire length of the pothole 101 has been described, but a part of the pothole 101, for example, the depth In some cases, the spiral flow path 3 is disposed only at a depth of 5 m or more, and a straight tubular flow path is connected from there to the ground surface. The ground from the ground surface to a depth of about 5m has a large temperature change depending on the season, and is not suitable for heat exchange with the heat medium (in winter, the temperature of the ground 100 near the surface decreases, so the heat medium radiates heat to the ground 100) In the summer, the temperature of the ground 100 near the surface rises, so the heat medium collects heat from the ground 100.) In order to reduce the heat loss by shortening the time for the heat medium to pass through the ground 100 near the surface. It is.
For the same reason, a heat insulating material such as glass wool may be disposed on the outer surface of the flow path near the ground surface of the underground heat exchanger 2. In some cases, a heat insulating material such as pumice or foamed glass is used only near the ground surface as the filler 102 to be filled in the pothole 101. Thereby, heat exchange between the heat medium and the ground 100 near the ground surface can be suppressed and heat loss can be reduced.
Moreover, in this Embodiment, although the underground heat exchanger 2 provided with the spiral flow path 3 was demonstrated, well-known underground heat exchangers, such as a double tube system, a U tube system, and a WU tube system, are used. It can also be used. Also in this case, since the thermal conductivity of the filler 102 is high, the heat exchange rate between the underground heat exchanger 2 and the ground 100 can be dramatically improved.

Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
(Experimental example 1)
FIG. 3 is a partial cross-sectional schematic view of an experimental apparatus for confirming the effect of the filler.
20 is a rectangular wooden frame assembled to a depth of 8 cm, a length of 40 cm, and a width of 8 cm, 21 is a filler filled in the wooden frame 20, and 22 is a depth of 4 cm and a width of 4 cm from the edge of the wooden frame 20. A rod-shaped 300 W heater embedded in a position of 10 cm in length and 0.8 cm in thickness, 23 is a thermocouple embedded in a position 4 cm deep and 4 cm wide, 2.5 cm away from the tip of the heater 22, 24 A thermocouple embedded at a depth of 4 cm and a width of 4 cm 5.0 cm away from the tip of the heater 22, and 25 is a thermocouple embedded at a depth of 4 cm and a width of 4 cm 7.5 cm away from the tip of the heater 22. The pair 26 is a thermocouple embedded at a position 4 cm deep and 4 cm wide, which is 10.0 cm away from the tip of the heater 22.
As the filler 21, silicon particles having an average particle diameter of 0.1 mm were used. As the silicon particles, 97% pure silicon particles generated when silicon dioxide was produced by reducing silicon dioxide during the production process of the semiconductor element material were used.
The filler 21 was dropped from a height of 5 cm above the wooden frame 20 to deposit the filler 21 in the wooden frame 20. The filling material 21 piled up on the wooden frame 20 was scraped off with a flat plate.
After filling the wooden frame 20 with the filler 21, the heater 22 was turned on, and the temperatures of the thermocouples 23, 24, 25, and 26 were measured every 10 seconds.

(Experimental example 2)
The thermocouple 23, the same as in Experimental Example 1 except that the filler 21 is a mixture of silicon particles having an average particle diameter of 20 mm and silicon particles having an average particle diameter of 0.1 mm in a weight ratio of 7: 3. The temperature of 24, 25, 26 was measured every 10 seconds.

(Comparative Example 1)
The temperature of the thermocouples 23, 24, 25, and 26 was measured every 10 seconds in the same manner as in Experimental Example 1 except that sea sand having an average particle diameter of 0.1 mm was used as the filler 21.

4 is a diagram showing a heat transfer state of the filler in Experimental Example 1, FIG. 5 is a diagram showing a heat transfer state of the filler in Experimental Example 2, and FIG. 6 is a heat transfer of the filler in Comparative Example 1. It is a figure which shows a state. The horizontal axis represents the elapsed time since the heater was turned on, and the vertical axis represents the temperature at each temperature measurement point by the thermocouple. The outside air temperature is also shown for comparison.
According to FIGS. 4 to 6, it is clear that the fillers in Experimental Examples 1 and 2 both have a large temperature rise at each temperature measurement point and have excellent heat conduction performance as compared with Comparative Example 1. It was. Particularly in Experimental Example 2, the filler is classified into a plurality of types for each particle size range, and a plurality of types of classified silicon particles are mixed. Therefore, 35 minutes after the heater is turned on, The temperature at a position 10 cm away was also about 5 degrees above the outside air temperature, and it was revealed that the heat conduction performance was particularly excellent.
According to the above embodiment, the heat conduction performance can be enhanced by using silicon grains having a purity of 90% or more. Therefore, when applied to the underground heat exchanger, the heat of the underground heat exchanger and the ground It is clear that the exchange rate can be dramatically improved and the utilization efficiency of geothermal heat can be enhanced by heat collection from the ground and heat radiation to the ground.

  The present invention relates to a buried structure of a ground heat exchanger that is buried in the ground and performs heat exchange with the ground, and dramatically improves the heat exchange rate between the ground heat exchanger and the ground, from the ground. The range of the earth that can use geothermal heat can be expanded by heat collection and heat radiation to the ground, the use efficiency of geothermal heat can be dramatically increased, and without further increasing the number of pits or the number of pits However, since the necessary heat exchange amount can be ensured, it is possible to provide a buried structure of the underground heat exchanger excellent in workability capable of preventing the construction period from being prolonged and the construction cost from increasing.

Schematic diagram of buried structure of underground heat exchanger according to Embodiment 1 The perspective view of the underground heat exchanger in Embodiment 1 Partial cross-sectional schematic diagram of the experimental device for confirming the effect of the filler The figure which shows the heat-transfer state of the filler in Experimental example 1 The figure which shows the heat-transfer state of the filler in Experimental example 2 The figure which shows the heat-transfer state of the filler in the comparative example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Embedment structure of underground heat exchanger 2 Underground heat exchanger 3 Spiral flow path 4 Spiral shaft space 5 Connecting member 6 Underground heat medium flow path 7 Spacing holding member 8 Base 9 Arm part 10 Fitting part 20 Wooden frame 21 Filler 22 Heater 23, 24, 25, 26 Thermocouple 100 Ground 101 Pothole 102 Filler

Claims (3)

A pit formed in the ground, a ground heat exchanger disposed in the pit, and groundwater filled in the hole and flowing in the ground permeate between the particles, and the ground heat exchanger and the ground heat exchanger An underground heat exchanger embedded structure comprising a granular filler that promotes heat exchange with the ground,
The filler contains silicon particles having a purity of 90% or more, the silicon particles are classified into a plurality of types for each particle size range, and the plurality of classified silicon particles are mixed. An underground heat exchanger buried structure.   2. The underground heat exchanger embedded structure according to claim 1, wherein the silicon particles are waste silicon particles generated in the process of manufacturing a semiconductor element material or silicon wafer crushing waste. The underground heat exchanger is formed at least partially in a spiral shape, a spiral flow path in which a heat medium flows, and a spiral axis space formed around a spiral axis inside the spiral flow path; A connecting member connected to the lower end of the spiral flow path; and a straight tube formed through the connection member and connected to the lower end of the spiral flow path and substantially parallel to the spiral axis direction of the spiral flow path. A ground heat medium passage disposed in the spiral shaft space, and a spacing member disposed at intervals along the underground heat medium passage, wherein the spacing member is A base formed in an annular shape with the underground heat medium flow passage inserted therein, an arm portion extended to the base portion, and an attachment formed in the end of the arm portion with the helical flow passage fitted therein buried structure of the underground heat exchanger according to claim 1 or 2, characterized in that it comprises a part, a.

Images