JP2009198037A - Geothermal heat gathering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a geothermal heat gathering device capable of restraining reduction in heat exchange efficiency, by preventing a heat loss in a pile head part of a heat gathering exclusive pile, when constructing the heat gathering exclusive pipe in land outside of a building, for using geothermal heat regardless of a new or existing building. <P>SOLUTION: A geothermal heat exchange circulating water pipe 2 is inserted from the upper end 1b of a hollow precast pile 1, and water 4 is filled inside the hollow precast pile 1, and a hollow part 6 is formed in an outer peripheral part of the pile 1 up to the predetermined depth from the ground surface 5a in the outer peripheral part of the hollow precast pile 1, and an upper part of the hollow part 6 is blocked up by a pile head cover 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a geothermal heat collecting apparatus using a ready-made pile whose end is closed.

  When the underground temperature exceeds a certain depth, it changes at a temperature of about the average annual temperature, which is lower than the outside temperature in summer and higher than the outside temperature in winter. There is a geothermal heat utilization system that uses the temperature difference between the underground and the outside air temperature to obtain the heat required for building air conditioning and road surface snow melting with a small amount of energy. This system has already spread widely in Europe and the United States, and has gradually started to spread in Japan.

  In geothermal heat utilization systems, the method of using foundation piles as a ground heat exchanger is attracting attention, but there are cases where the number of foundation piles alone cannot cover the air conditioning load. A method of constructing a pile separately is conceivable.

  In general, when a heat-collecting pile is constructed on land outside a building, heat loss increases due to the influence of fluctuations in outside air temperature and solar radiation, so Patent Document 1 is proposed and is also shown in Patent Document 1. Thus, in the circulating water reciprocating pipe (heat medium flow pipe) for underground heat exchange, measures are taken to prevent heat loss by covering the periphery of the outlet pipe with a heat insulating material.

  However, while the ground surface temperature in summer rises to about 45 ° C, the circulating water temperature at the underground heat exchanger entrance is often lower than 45 ° C and circulates at the underground heat exchanger entrance. Water gets heat from the ground and the circulating water temperature rises. Therefore, since the heat acquired by the air-conditioning exhaust heat and the entrance is introduced into the underground heat exchanger, the efficiency is lowered. In winter, the ground surface may become lower than the outside air temperature due to radiative cooling, and the circulating water is cooled at the entrance of the underground heat exchanger, resulting in a problem of reduced efficiency. Moreover, since there is no specific disclosure about the range in which the heat insulating material is applied, it is not shown to what extent the heat insulation is effective.

As a method for solving this problem, Patent Document 2 has been proposed, and a heat-extracting pile is constructed under the floor of a building separately from the foundation pile to make it less susceptible to the influence of outside air temperature and solar radiation.
JP 2004-169985 A JP 2006-343004 A

  In the method of Patent Document 2, the outlet of the heat medium flow pipe serves as the upper end of the pile, but it cannot be said that the maintainability is high because it is provided in the underfloor space. This method can be constructed at the time of new construction, but it cannot be used in existing buildings because it cannot be piled up inside the building.

  The present invention has been made in view of the circumstances as described above. In order to enable the use of underground heat regardless of whether the building is newly constructed or existing, a pile exclusively for heat collection is constructed on the land outside the building. Provides a geothermal heat sampling device that prevents heat loss at the pile head of a dedicated pile for heat collection, or reduces the load on the underground heat exchanger and suppresses the decline in heat exchange efficiency. The purpose is to do.

  In order to solve the above problems, the present invention has the following features.

[1] A geothermal heat sampling system in which a hollow tube with a closed end is inserted into the ground, a circulation pipe for heat collection is arranged inside the hollow tube, and a filler is installed inside the hollow tube. In the thermal device,
A geothermal heat collecting apparatus characterized in that a space is formed in the outer peripheral portion of the hollow tube from the ground surface to a predetermined depth and the upper portion thereof is closed.

  [2] The geothermal heat collecting apparatus according to [1], wherein a heat insulating material is installed in a space formed in an outer peripheral portion of the hollow tube.

  [3] The underground heat collecting apparatus according to [1], wherein a space formed in an outer peripheral portion of the hollow tube is filled with a water retention material.

  [4] The underground heat collecting apparatus according to any one of [1] to [3], wherein a depth of a space formed in an outer peripheral portion of the hollow tube is 50 cm or more.

  [5] The underground heat collecting apparatus according to any one of [1] to [4], wherein a depth of a space formed in an outer peripheral portion of the hollow tube is 3 m or less.

  In the present invention, a hollow tube (pile) whose tip is closed is penetrated into the ground (ground), a circulation pipe for heat collection is arranged inside the hollow tube, and a filler is placed inside the hollow tube. In the geothermal heat collecting device that has been constructed, a space is formed from the ground surface to a predetermined depth in the outer peripheral portion of the hollow tube, and the upper portion is closed, so that the pile head portion is insulated from the ground. , Can reduce the heat effect. As a result, heat loss at the pile head portion can be prevented, and a decrease in heat exchange efficiency can be suppressed.

  Furthermore, the said effect can be made more reliable by constructing a heat insulating material in the space formed in the outer peripheral part of the said hollow tube.

  Also, by filling the space formed in the outer peripheral portion of the hollow tube with a water retention material, the water inside the water retention material held by rain or water spray evaporates from the top, and the ground surface portion that has risen due to solar radiation or the like The heat effect of can be removed.

  Embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 is an explanatory diagram of a geothermal heat collecting apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the structure of the underground heat collecting apparatus according to the first embodiment uses a hollow ready-made pile 1 that closes the tip (lower end) 1a and penetrates into the ground 5 as a ground heat exchanger. It is the structure of the pile head of the hollow ready-made pile, and it inserts the circulating water piping 2 for underground heat exchange into the hollow ready-made pile 1 from the rear end (upper end) 1b of the hollow ready-made pile 1, and the hollow ready-made pile 1 Is filled with a filler (in this case, water) 4, and on the outer periphery of the pile head (the outer periphery of the hollow ready-made pile 1) from the ground surface 5 a to a predetermined depth than the outer periphery of the pile 1. A predetermined amount (for example, about 5 cm) of a large hollow portion (space portion) 6 is formed, and the upper portion of the hollow portion 6 is closed with a pile skull 3.

  As a method for forming the hollow portion 6, it is desirable to excavate before the hollow ready-made pile 1 penetrates, and a casing (not shown) such as a steel pipe or a resin pipe may be used to protect the hole wall. As described above, the upper portion of the hollow portion 6 is closed by the pile head 3, but the pile head (the upper end of the hollow ready-made pile 1) 1b is placed below the ground surface 5a, or the upper end of the casing is the ground surface 5a. The pile head 1b and the pile cradle 3 are not brought into contact with each other by, for example, further upward.

  Thus, in this Embodiment 1, since the hollow part 6 is formed in the outer peripheral part of the hollow ready-made pile 1 from the ground surface 5a to the predetermined depth, and the upper part is obstruct | occluded with the pile skull 3. The pile head portion is insulated from the ground 5, and the thermal effect can be mitigated. As a result, heat loss at the pile head portion can be prevented, and a decrease in heat exchange efficiency can be suppressed.

  In addition, what is necessary is just to determine the size of the hollow ready-made pile 1, and the size and quantity of the circulating water piping 2 as needed, and is not prescribed | regulated here.

  In addition, the depth of the hollow portion 6 provided on the outer periphery of the pile head is 50 cm or more, preferably 3 m or less at the deepest, and is approximately one-fifth of the total length so as not to be excessive compared with the total length of the underground heat exchange device. The following is desirable. The diameter of the hollow portion 6 can be arbitrarily determined.

  By the way, it is known from the underground temperature observation that the thermal effect of the ground surface part is large up to about 50 cm deep, and by taking measures in the affected range, the thermal effect should be effectively eliminated at low cost. Therefore, it is desirable that the depth of the hollow portion 6 formed on the outer peripheral portion of the hollow ready-made pile 1 is 50 cm or more.

  However, since the underground heat exchange device collects heat or exhausts heat by contact with the ground 5, if the range of heat insulation or the like is too large, the effective length of the underground heat exchange device will be insufficient. Therefore, it is necessary to set the range clearly. As shown in FIG. 2, the underground temperature at a depth of about 5 m or more from the surface of the earth is almost unaffected by the outside air temperature and the like, and is maintained at a substantially constant temperature (hereinafter referred to as a deep temperature). On the other hand, the underground temperature of the part near the ground surface from the ground surface to about 5m is affected by the outside air temperature etc., but when looking at the data in January and July, the inflection point is about 3m deep from the ground surface. Yes, the underground temperature in this area is lower than the deep temperature in summer and higher than the deep temperature in winter. By effectively utilizing this part, an effective design for heat collection can be performed. Therefore, by setting the depth of the hollow part 6 formed on the outer peripheral part of the hollow ready-made pile 1 to 3 m or less, in the summer, from the deep part It is possible to utilize the low temperature part and the hotter part than the deep part in winter.

[Embodiment 2]
FIG. 3 is an explanatory diagram of a geothermal heat collecting apparatus according to Embodiment 2 of the present invention.

  As shown in FIG. 3, the geothermal heat collecting apparatus according to the second embodiment is obtained by constructing a heat insulating material 7 in the hollow portion 6 in the geothermal heat collecting apparatus of the first embodiment.

  Thereby, in this Embodiment 2, the effect of Embodiment 1 of relieving the thermal influence to a pile head part can be made more reliable.

  The heat insulating material 7 is preferably a resin-based heat insulating material with low water absorption, but if it is made higher than the ground surface using a casing for the hole wall (not shown), a fiber-based heat insulating material such as glass wool or rock wool is used. It may be used. The thickness of the heat insulating material 7 is preferably 2.5 cm or more for the resin heat insulating material and 5 cm or more for the fiber heat insulating material. Moreover, as for the heat insulating material 7, it is desirable to construct also between the pile head 3 and the pile head 1b besides the hollow part 6 of the outer periphery of the pile 1. FIG. Furthermore, it is more effective to insulate the ground portion of the circulating water pipe 2.

[Embodiment 3]
FIG. 4 is an explanatory diagram of a geothermal heat collecting apparatus according to Embodiment 3 of the present invention.

  As shown in FIG. 4, the geothermal heat collecting apparatus according to the third embodiment arranges the pile head 1b at a position higher than the ground surface 5b with respect to the geothermal heat collecting apparatus of the second embodiment. It is a thing. In this case, the heat insulating material 7 is continuously constructed also about the part which comes out on the ground. It is more desirable to insulate the circulating water pipe 2 together and to apply an aluminum foil or the like on the surface of the heat insulating material 7 to reduce the influence of solar radiation.

[Embodiment 4]
FIG. 5 is an explanatory diagram of a geothermal heat collecting apparatus according to Embodiment 4 of the present invention.

  As shown in FIG. 4, the geothermal heat collecting apparatus according to the fourth embodiment is constructed by installing a water retaining material 8 in the hollow portion 6 in the geothermal heat collecting apparatus of the first embodiment.

  As a result, in the fourth embodiment, the water inside the water retaining material 8 held by rain or water spray evaporates from the upper portion, so that the thermal effect of the portion of the ground surface 5a that has risen due to solar radiation or the like can be removed. . Therefore, this is an effective form for a geothermal heat collecting device for cooling.

  The water retention material 8 is arbitrarily selected from a polymer, an inorganic porous material, etc., but the inorganic porous material is most desirable, and steelmaking slag, rock wool foam, etc. are mixed with cement as necessary. Fill and install.

  Moreover, in this Embodiment 4, the efficiency is improved by arrange | positioning the pile skull 3 in the position below the ground surface 5a, and constructing the water retaining material 8 also in the upper part. Furthermore, a watering device may be provided to sprinkle the water retaining material 8 portion.

It is explanatory drawing of the geothermal heat collecting apparatus which concerns on Embodiment 1 of this invention. It is the figure which showed the underground temperature distribution for every season. It is explanatory drawing of the geothermal heat collecting apparatus which concerns on Embodiment 2 of this invention. It is explanatory drawing of the geothermal heat collecting apparatus which concerns on Embodiment 3 of this invention. It is explanatory drawing of the geothermal heat collecting apparatus which concerns on Embodiment 4 of this invention.

Explanation of symbols

1 Hollow ready-made pile 1a Tip (lower end) of hollow ready-made pile
1b Rear end (upper end) of hollow ready-made pile
2 Circulating water piping 3 Pile skull 4 Filling material (filled water)
5 Ground 5a Ground surface 6 Hollow part 7 Heat insulating material 8 Water retaining material

Claims (5)

In a geothermal heat collecting apparatus in which a hollow tube with a closed end is inserted into the ground, a circulation pipe for heat collection is arranged inside the hollow tube, and a filler is installed inside the hollow tube ,
A geothermal heat collecting apparatus characterized in that a space is formed in the outer peripheral portion of the hollow tube from the ground surface to a predetermined depth and the upper portion thereof is closed.   The underground heat collecting apparatus according to claim 1, wherein a heat insulating material is installed in a space formed in an outer peripheral portion of the hollow tube.   The geothermal heat collecting apparatus according to claim 1, wherein the space formed in the outer peripheral portion of the hollow tube is filled with a water retention material.   The depth of the space formed in the outer peripheral part of the said hollow tube is 50 cm or more, The geothermal heat collecting apparatus in any one of Claims 1-3 characterized by the above-mentioned.   The depth of the space formed in the outer peripheral part of the said hollow tube is 3 m or less, The geothermal heat collecting apparatus in any one of Claims 1-4 characterized by the above-mentioned.

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