JP2012255632A - Heat transfer packing material, and geothermal heat exchanging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transfer material in a heat transfer packing material at a desired position in a bored hole without requiring complicated blending adjustment.SOLUTION: A pellet 12A as a heat transfer packing material 12 is formed by adding iron powder 12C to bentonite 12B. The pellet 12A is supplied in a bore hole H formed at the ground G, and water is supplied thereto to make the pellet 12A wet, thereby forming the heat transfer packing material 12. Thus, the heat transfer packing material 12 is solidified as the granular pellet 12A, and the iron powder 12C is added to the pellet 12A. and as a result, even if the pellet 12A is supplied in the bored hole H, the iron powder 12C remains in the pellet 12A, and hardly drops from the pellet 12A. Consequently, the heat transfer packing material 12 can be filled in the bored hole H while the iron powder 12C with the heat transfer characteristic more excellent than that of the bentonite 12B is dispersed therein.

Description

  The present invention relates to a geothermal heat exchange device in a geothermal heat utilization system for residential use, and in particular, geothermal heat that exchanges heat with soil using a drilling hole excavated from the ground toward the ground. The present invention relates to a heat transfer filler used in an exchange device and an underground heat exchange device.

  The temperature in the ground is relatively stable compared to the outside temperature, with little temperature change throughout the year. In particular, the underground below the ground surface is not affected by the outside air at a certain depth or more and can obtain a constant temperature. For example, in the Japanese climate, the underground temperature is In winter, it is higher than the outside temperature. Therefore, a pile-shaped underground heat exchange device is buried in the ground, and heat exchange is performed between the underground heat exchange device and an air conditioner provided in a building on the ground, thereby substituting the underground heat. A ground heat utilization system used as a heat source for air conditioning equipment has been proposed. As this type of system, a heat medium heat transfer pipe (heat exchange pipe) that circulates the heat medium between the ground and the ground is disposed in the hollow interior of the foundation pile buried under the foundation of the building. A configuration in which the periphery of the medium heat transfer tube is filled with a heat transfer filler having predetermined heat transfer characteristics is known. This heat transfer filler promotes heat exchange between the underground and the heat medium heat transfer tube, and a configuration is known that employs water from the viewpoint of heat transfer characteristics and heat capacity.

  Further, Patent Document 1 forms a heat transfer filler by mixing a heat transfer material such as iron powder having good heat transfer characteristics and a grout material as a curable material, and in a fluid state before the grout material is cured. The structure which hardens a grout material after pouring a heat-transfer filler into a drilling hole is disclosed.

JP 2002-54850 A

  However, since the specific gravity of the fluid grout material and iron powder is different, if the fluidized heat transfer filler mixed with iron powder is poured into the hole, the iron powder in the heat transfer filler Gravity falls towards the bottom. This makes it difficult to uniformly disperse the iron powder from the bottom to the top in the drilling hole. In this regard, Patent Document 1 discloses disclosure of preventing the fall of iron powder by adjusting the preparation of iron powder, etc., but such preparation adjustment includes not only the weight of iron powder but also iron. There is a problem that the preparation becomes extremely complicated because the preparation of the powder, the diameter of the drilling hole, the viscosity of the grout material, and the like are required.

  Therefore, the present invention has been made to solve such a problem, and the heat transfer material in the heat transfer filler can be provided at a desired position in the drilling hole without requiring complicated preparation adjustment. An object of the present invention is to provide a heat transfer filler and a ground heat exchange device.

  In order to solve the above problems, a heat transfer filler according to the present invention is a heat transfer filler filled around a heat exchange pipe inserted in a drilling hole provided in the ground, and has a predetermined heat transfer filler. It is characterized by comprising pellets formed by adding a powder having better heat transfer characteristics than the main material to the main material having the characteristics.

  In this invention, the powder as a heat transfer material is added to the main material to make a heat transfer filler, and further, the heat transfer filler is solidified into pellets as pellets, so when the heat transfer filler is put into the drilling hole Even so, the powder remains in the pellet, and therefore, the powder does not separate from the main material and accumulate in a part of the drilling hole. Thereby, the inside of the drilling hole can be filled with the heat transfer filler while the powder as the heat transfer material having better heat transfer characteristics than the main material is dispersed. Thus, even when a powder having a specific gravity different from that of the main material is used as the heat transfer material, the main material and the powder are not separated from each other, and the powder is evenly dispersed in the drilling holes. be able to. As described above, according to the present invention, the heat transfer material (powder) in the heat transfer filler is provided at a desired position in the drilling hole without requiring complicated preparation adjustment of the material forming the heat transfer filler. That is, the heat transfer material can be held at the initial height position.

  The main material is preferably made of bentonite. Bentonite has a swelling property that swells when it is supplied with water. For this reason, after throwing in the pellets, the pellets swell by supplying water into the drilling holes, thereby filling the gaps between the pellets. Thereby, the heat-transfer efficiency in a heat-transfer filler can be improved further. Bentonite is not stirred and maintains its viscosity. For this reason, even when a powder having a high specific gravity is used, the main material and the powder are not separated, and the powder can be evenly dispersed in the drilling holes.

  The powder is preferably made of iron powder or graphite powder. When iron powder or graphite powder is used as the powder, the heat transfer characteristics of the heat transfer filler are better than the soil, and the heat exchange between the heat medium flowing in the heat exchange pipe and the soil is further improved. Can be made. Also, by using iron powder or graphite powder as the powder, it is possible to easily create a heat transfer filler with good heat transfer characteristics simply by adding these iron powder or graphite powder to the main material. .

  Further, the underground heat exchange device according to the present invention includes a heat exchange pipe inserted into a drilling hole provided in the ground, and a heat transfer filler filled around the heat exchange pipe. In the heat exchange apparatus, the heat transfer filler is formed of pellets formed by adding powder having better heat transfer characteristics than bentonite to bentonite as a main material.

  According to the present invention, the powder as the heat transfer material is added to the bentonite as the main material to form the heat transfer filler, and further, the heat transfer filler is solidified in the form of pellets. Even when it is put into the drilling hole, the powder stays in the pellet, and therefore, the powder does not separate from the main material and accumulate in any part of the drilling hole. As a result, the heat transfer filler can be filled into the drilling holes while the powder, which is a heat transfer material having better heat transfer characteristics than the main material, is dispersed. Thus, even when powder having a specific gravity different from that of bentonite is used as the heat transfer material, the powder can be evenly dispersed in the drilling holes without separation of bentonite and powder. it can. In addition, bentonite has a swelling property that swells when supplied with water. For this reason, after throwing in the pellets, the pellets swell by supplying water into the drilling holes, thereby filling the gaps between the pellets. Thereby, heat-transfer efficiency can be improved further. Bentonite is not stirred and maintains its viscosity. For this reason, even when a powder having a high specific gravity is used, the bentonite and the powder are not separated, and the powder can be evenly dispersed in the drilling holes. As described above, according to the present invention, the heat transfer material (powder) in the heat transfer filler can be provided at a desired position in the drilling hole without requiring complicated preparation adjustment.

  Moreover, it is preferable that the outer periphery of the heat transfer filler is in contact with the underground soil forming the peripheral wall of the drilling hole. In this case, since the heat transfer filler is in direct contact with the underground soil, heat exchange between the filler and the underground soil is possible, and the heat transfer efficiency can be further improved. Moreover, after the swelling of bentonite, the heat transfer filler can be brought into contact with the groundwater of the underground soil. Groundwater is an effective heat source in a specified temperature range that depends on the temperature of the underground soil, and fluid (groundwater) at a specified temperature is constantly updated in the heat exchange area, so heat transfer efficiency is higher than that of underground soil. Is expensive. For this reason, according to this structure, it becomes what can heat-exchange between the heat-transfer fillers and the groundwater which is a heat source, and can further improve heat-transfer efficiency.

  According to the present invention, the powder as the heat transfer material in the heat transfer filler can be provided at a desired position in the drilling hole without requiring complicated preparation adjustment.

It is a figure showing the whole underground heat exchange system composition concerning an embodiment. It is a figure which shows the detailed structure of the pellet before swelling. It is a flowchart which shows the process of filling a heat-transfer filler in a drilling hole. It is a flowchart which shows the modification of the process of filling a heat-transfer filler in a drilling hole. It is a figure which shows a mode that a heat-transfer filler is filled. It is a figure which shows the state before the swelling of the pellet thrown in in the drilling hole. It is a figure which shows the state after the swelling of the pellet thrown in in the drilling hole.

  Hereinafter, an embodiment in which a ground heat exchange device according to the present invention is applied to a ground heat exchange system will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram illustrating the overall configuration of the embodiment. As shown in FIG. 1, the underground heat exchange system 1 includes an underground heat exchange device 10, a heat pump 20, and an indoor unit 30.

  The underground heat exchange device 10 includes an underground heat exchange pipe 11 installed in a borehole H excavated from the ground surface of soil G toward the ground, and an underground heat exchanger pipe in the borehole H. 11 and a heat transfer filler 12 filled around the periphery.

  The underground side heat exchange pipe 11 includes an introduction side pipe 11A that guides the heat medium from the heat pump 20 side to the hole H side, and a lead-out side pipe 11B that leads the heat medium from the hole H side to the heat pump 20 side. Yes. One end of each of the introduction-side pipe 11A and the outlet-side pipe 11B extends to the vicinity of the bottom of the hole H, and the one ends are connected to each other so as to be able to circulate. Further, the other end of each of the introduction side pipe 11 </ b> A and the outlet side pipe 11 </ b> B extends to the heat pump 20, and the other ends are connected so as to be able to circulate within the heat pump 20. Thus, a closed flow path is formed from the bottom of the hole H to the heat pump 20 by the underground heat exchange pipe 11.

  A circulation pump 21 is attached to the underground heat exchange pipe 11. The circulation pump 21 functions as a pump that circulates the heat medium in the underground heat exchange pipe 11. Thereby, by operating the circulation pump 21, the heat medium flows in the underground heat exchange pipe 11, and the heat transmitted to the heat medium in the underground heat exchange pipe 11 in the drilling hole H, It can be used on the heat pump 20 side.

  In addition, as a material of the underground heat exchange pipe 11, for example, a resin (crosslinked polyethylene, metal reinforced polyethylene) or metal (copper, stainless steel) pipe can be used. Moreover, a direct current pump or an alternating current pump can be used as the circulation pump 21, and the output can be selected according to the total length of the underground heat exchange pipe 11.

  Moreover, the hole H can use the hole whose diameter is 100-200 mm and whose depth is 5-100 m, for example. Further, as a method for forming the hole H, boring, rotary embedding, or hitting can be used.

  The heat transfer filler 12 is formed by a plurality of pellets 12 </ b> A introduced into the hole H. The pellet 12A contains water and is in a swollen state. FIG. 2 shows the detailed structure of the pellet before swelling. As shown in FIG. 2, the pellet 12A is formed by adding iron powder (powder) 12C having better heat transfer characteristics than bentonite 12B to bentonite 12B as a main material. The pellet 12A is obtained by drying bentonite 12B to which iron powder 12C is added, and is formed in a cylindrical shape having a size of about 5 to 20 mm in a state before swelling. Moreover, the pellet 12A has a specific gravity of 1 or more. Note that the size of the pellets 12A may be constant, or as shown in FIG. 2, pellets 12A having different sizes may be mixed.

  In addition, it is preferable to use what has a material characteristic whose main component contains montmorillonite, quartz, mica, feldspar, etc. and whose thermal conductivity is 0.2-1.0 W / mK as bentonite 12B. Furthermore, in this embodiment, it is more preferable to use the bentonite 12B having better thermal conductivity than dry sand (thermal conductivity 0.3 W / mK) and water (thermal conductivity 0.2 W / mK). Moreover, it is preferable that the mixing ratio of bentonite 12B and iron powder 12C when forming pellet 12A is, for example, about 60% to 80% for bentonite 12B and about 20% to 40% for iron powder 12C.

  The heat pump 20 performs heat exchange with the heat medium flowing through the indoor-side heat exchange pipe 31 on the indoor unit 30 side, using heat obtained through the heat medium flowing through the underground-side heat exchange pipe 11. is there.

  The indoor unit 30 is attached to a room in a house and performs cooling or heating using a heat medium flowing through the indoor heat exchange pipe 31. As the indoor unit 30, for example, an air conditioner or a floor heating facility can be used.

  Next, a method for filling the heat transfer filler 12 in the hole H will be described. FIG. 3 is a flowchart showing a process of filling the heat transfer filler into the hole, and FIG. 5 is a diagram showing a state where the heat transfer filler is filled. First, as shown in FIG. 5A and FIG. 5B, excavation machine 100 is used to excavate from the ground surface of soil G toward the ground, thereby forming hole H (step S101). . Then, as shown in FIG.5 (c), the underground side heat exchange pipe 11 is installed in the drilling hole H (step S102).

  Next, as shown in FIG. 5D, pellets 12A as the heat transfer filler 12 are put into the hole H (step S103). The amount of pellets 12 </ b> A introduced into the hole H is an amount that allows water to reach all the introduced pellets 12 </ b> A when water is supplied to the pellets 12 </ b> A. Thereby, all the pellets 12A are brought into a swollen state. For this reason, the gap between the pellets 12A is remarkably narrowed by swelling of the pellets 12A, or the pellets 12A are in close contact with each other and buried. As a result, the air retention space that hinders heat transfer between the pellets 12A is reduced, and the heat transfer characteristics of the heat transfer filler 12 are improved. In the present embodiment, for example, the amount of the pellet 12A to be charged into the hole H at the first time may be an amount that the hole H is filled with the pellet 12A up to the eighth depth. However, depending on the diameter of the hole H and the swelling performance of the pellet 12A, the amount of the pellet 12A to be input is smaller than the amount that the inside of the hole H is filled with the pellet 12A until the eighth depth. Alternatively, it may be an amount in which the hole H is completely filled.

  Next, as shown in FIG. 5 (e), water W is supplied to the pellets 12A in the hole H to make the pellets 12A swell (step S104). The pellet 12A rapidly expands immediately after the water W is charged, and continues to expand gently after the eighth hour after the water W is charged, and the expansion ends in about one week. As shown in FIG. 6, before supplying water W into the hole H, there is a gap between the pellets 12A. By supplying water W to the pellet 12A to make the pellet 12A swell, the pellet 12A expands as shown in FIG. 7, and the gap between the pellet 12A and the gap between the pellet 12A and the peripheral wall of the hole H are formed. Buried.

  In addition, this process is not limited to said construction, As shown to the flowchart of FIG. 4, the pellet 12A of 10%-20% of the whole is injected into the drilling hole H, for example (step S103), and then water is supplied. After the pellet 12A is supplied (step S104) and swelled to some extent, if the inside of the hole H is not filled with the swelled pellet 12A (step S104A: NO), the pellet is again placed on the swelled pellet 12A. 12A is charged (step S103), and then water is supplied (step S104)..., And the swollen pellets 12A in the hole H have the same height as the ground surface (step S104A: YES). It is also possible to adopt a configuration that repeats a plurality of times.

  Through these steps, filling the hole H with the pellets 12A in a swollen state completes the filling of the heat transfer filler 12 as shown in FIG. 5 (f) (step S105).

  The present embodiment is configured as described above, and iron powder 12C is added to bentonite 12B to form heat transfer filler 12, and further, heat transfer filler 12 is pelletized as pellets 12A, so that heat transfer filler is formed. Even when 12 pellets 12A are put into the drilling hole H, the iron powder 12C stays in the pellet 12A. Therefore, the iron powder 12C separates from the bentonite 12B and accumulates in one of the drilling holes H. There is no end. Thereby, the inside of the drilling hole H can be filled with the heat transfer filler 12 while the iron powder 12C having better heat transfer characteristics than the bentonite 12B is dispersed. Thus, even if iron powder 12C having a higher specific gravity than bentonite 12B is used as the heat transfer material, the bentonite 12B and iron powder 12C are not separated, and the iron powder 12C is formed in the hole H. Can be evenly distributed. As described above, according to this embodiment, the iron powder 12C in the heat transfer filler 12 can be provided at a desired position in the drilling hole H without requiring complicated preparation adjustment of the heat transfer filler 12. The iron powder 12C can be held at the initial height position.

  Further, the bentonite 12B has a swelling property that swells when supplied with water W. For this reason, after supplying the pellets 12A, the water 12 is supplied into the hole H to swell the pellets 12A, thereby filling the gaps between the pellets 12A. Thereby, the heat transfer efficiency of the heat transfer filler 12 can be further improved. Moreover, the bentonite 12B is not stirred and maintains the viscosity. For this reason, even if it is a case where iron powder 12C with heavy specific gravity is used, bentonite 12B and iron powder 12C do not isolate | separate, but iron powder 12C can be disperse | distributed uniformly in the drilling hole H.

  Moreover, when using iron powder 12C as a heat transfer material added to bentonite 12B, the heat transfer characteristics of the heat transfer filler 12 are better than those of the soil G, and the heat medium and soil flowing through the underground heat exchange pipe 11 Heat exchange with G can be further improved. Moreover, it becomes possible to easily produce the heat transfer filler 12 having good heat transfer characteristics simply by adding the iron powder 12C to the bentonite 12B.

  Further, since the heat transfer filler 12 is in direct contact with the soil G, heat exchange between the heat transfer filler 12 and the soil G is possible, and the heat transfer efficiency can be further improved. Further, the heat transfer filler 12 can be brought into direct contact with the ground water of the soil G. The groundwater is an effective heat source in a predetermined temperature range depending on the temperature of the soil G, and the fluid (groundwater) at the predetermined temperature is constantly renewed in the heat exchange portion, so that the heat transfer efficiency is higher than that of the soil G. . For this reason, the heat transfer filler 12 can exchange heat with groundwater as a heat source, and heat transfer efficiency can be further improved.

  Further, since the heat transfer filler 12 is in contact with the peripheral wall of the hole H, that is, the heat transfer filler 12 is in direct contact with the soil G, the pellet 12A is also swollen by moisture from the soil G. be able to.

  The present invention is not limited to the above-described embodiment. For example, in the above embodiment, the iron powder 12C is used as the heat transfer material to be added to the bentonite 12B. However, the present invention is not limited thereto. For example, even when the graphite powder is used, the iron powder 12C is used. The same effect can be obtained. In addition, when graphite powder is used, it is preferable to use a graphite having a purity of 80% or more. In addition to iron powder and graphite powder, other materials can be used as the heat transfer material.

  Moreover, in the pellet 12A, the addition ratio of the iron powder 12C can be changed as appropriate. For example, a pellet 12A having a high ratio of iron powder 12C and a pellet 12A having a low ratio of iron powder 12C may be mixed and used as the heat transfer filler 12.

  Further, by conducting a boring survey or the like, the layer configuration of the soil G in which the hole H is provided can be grasped, and the thermal efficiency of each layer of the soil G can be known. As a result, when the pellet 12A is put into the hole H, the heat transfer in the hole H is made such that the pellet 12A having the same thermal efficiency as this layer is put at the height position of the layer having high thermal efficiency. It is also possible to form the filler 12 in a layered manner in accordance with the surrounding soil. In this embodiment, since it is the structure which forms the heat-transfer filler 12 using the pellet 12A, the construction which forms the heat-transfer filler 12 in layers according to the thermal efficiency of each layer of the soil G is extremely easily performed. Can do. Conventionally, since the liquid (slurry) or the like is uniformly filled from the bottom to the top of the drilling hole, it is difficult to form the heat transfer filler in layers.

  Moreover, in this embodiment, although the pellet 12A was made into cylindrical shape, it is not limited to cylindrical shape, The pellet of an appropriate shape can be used.

  Moreover, in this embodiment, although it was the structure which throws the pellet 12A which is the heat-transfer filler 12 in the hole H, a steel pipe is inserted in the hole H, and the pellet which is the heat-transfer filler 12 in the said steel pipe 12A may be inserted.

  In the present embodiment, the case where the underground heat exchange device 10 is formed by installing the underground heat exchange pipe 11 and filling the heat transfer filler 12 in one hole H has been described as an example. The underground heat exchange device 10 may be formed by installing the underground heat exchange pipe 11 and filling the heat transfer filler 12 in the plurality of holes H, respectively.

  DESCRIPTION OF SYMBOLS 1 ... Ground heat exchange system, 10 ... Ground heat exchange apparatus, 11 ... Ground side heat exchange pipe, 12 ... Heat transfer filler, 12A ... Pellets, 12B ... Bentonite (main material), 12C ... Iron powder (powder) Body), G ... soil, H ... drilling.

Claims (5)

A heat transfer filler filled around a heat exchange pipe inserted into a drilling hole provided in the ground, and has a heat transfer characteristic better than that of the main material having a predetermined heat transfer characteristic A heat transfer filler comprising pellets formed by adding powder.   The heat transfer filler according to claim 1, wherein the main material is bentonite.   The heat transfer filler according to claim 1 or 2, wherein the powder is made of iron powder or graphite powder. A ground heat exchange device comprising a heat exchange pipe inserted into a drilling hole provided in the ground, and a heat transfer filler filled around the heat exchange pipe,
The heat transfer filler is composed of pellets formed by adding powder having better heat transfer characteristics than bentonite to bentonite as a main material.   5. The underground heat exchange device according to claim 4, wherein an outer periphery of the heat transfer filler is in contact with an underground soil forming a peripheral wall of the drilling hole.

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