JP2006220402A - Heat collection pipe burying method used for underground heat system, and underground heat system using the burying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burying method for a heat collection pipe used for an underground heat system allowing low-cost construction even in a dense residential area or a narrow area, and capable of performing efficient heat exchange. <P>SOLUTION: In this burying method for the heat collection pipe 7 used for the underground heat system connected with a heat exchanger 5, feeding a cooling medium heat-exchanged by the heat exchanger 5 into the ground 6 to perform the heat exchange, a pit 20 allowing vertical burying of the heat collection pipe 7 wound in a loop state is dug out in land, and the heat collection pipe 7 is buried in the dug-out pit 20 in a state that a loop portion 7C of the heat collection pipe 7 is held such that the loop portion 7c is horizontally shifted and comes into a vertical state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for burying a heat collecting tube used in a geothermal system.

  A heat collection pipe is introduced into a heat exchanging well excavated in the ground or an embedded steel pipe pile, a heat exchanger is connected to the introduced heat collection pipe, and the cooling medium heat exchanged by the heat exchanger is conveyed into the ground to absorb heat. Various geothermal systems that collect heat have been proposed. In such a geothermal system, costs are required for excavation of a heat exchange well into which a heat collecting pipe is introduced and for the embedding of steel pipe piles, so that the system becomes expensive. Therefore, a method has been proposed in which a hole is excavated in the ground, and a heat collecting tube is wound in a loop shape inside the excavated hole and buried horizontally.

However, in the method of burying the heat collection tubes in a horizontal loop shape, a space in the horizontal direction is required when excavating the holes, and it is difficult to excavate holes in densely populated or confined areas. I couldn't. In order to form a loop without crushing the heat collecting tube, the loop diameter is inevitably determined by the material of the heat collecting tube. Further, in order to increase the heat exchange efficiency by the heat collecting tube, it is preferable to embed the loop in the horizontal direction rather than embed it concentrically because the surface area in contact with the ground can be increased. For this reason, the area of the hole to be excavated in the horizontal direction requires at least a width that allows the loop diameter and a length that allows the heat collection tube length when the loop is shifted. In order to efficiently dissipate heat from the heat collection pipe to the ground or absorb heat from the heat collection pipe, and to protect the heat collection pipe, bury the heat collection pipe at a certain depth from the ground surface and place it on the upper part of the buried heat collection pipe. Therefore, it is necessary to stack a certain amount of earth and sand, and the amount of excavation naturally increases. For this reason, the storage place for the excavated earth and sand (generated soil) inevitably requires a large area, and the processing is also expensive, resulting in an increase in cost.
The present invention provides a method of burying a heat collecting pipe used in a geothermal system that can be embedded at low cost even in densely populated houses and narrow spaces, and can perform efficient heat exchange, and a geothermal system using this method. That is the purpose.

In order to achieve the above object, the present invention is a method of burying a heat collecting pipe used in a ground heat system that is connected to a heat exchanger and transports a cooling medium heat exchanged by the heat exchanger to the ground to exchange heat. A hole that can be buried vertically by wrapping a heat collection tube in a loop shape is excavated in the ground, and the loop portion of the heat collection tube is shifted horizontally in the excavated hole, and the loop portion is in a vertical state. It is characterized by burying heat collecting tubes.
The underground heat system according to the present invention is characterized by having a heat collection pipe embedded by the above-described embedding method.

  According to the present invention, a hole that can be embedded vertically by winding a heat collection tube in a loop shape is provided in the ground, and the loop portion of the heat collection tube is shifted horizontally in the excavated hole, and the loop portion is in a vertical state. Since the heat collection pipe is buried so that the width of the hole to be excavated is the width in the thickness direction of the heat collection pipe buried by shifting the loop, even in densely populated areas and narrow areas where there is little space in the horizontal direction The hole for burying the heat collection tube can be excavated, and the heat collection tube can be buried. Moreover, the place where the excavated earth and sand (generated soil) is stored is narrow and the amount of processing is reduced, so that the cost can be further reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the code | symbol 1 shows a geothermal system. The underground heat system 1 is connected to an air conditioner 3 installed in a room 2, a heat pump 4, and a water-cooled heat exchanger 5 of the heat pump 4, and uses cooling water as a cooling medium heat-exchanged by the heat exchanger 5. A heat collecting tube 7 is provided for exchanging heat by transferring it to the underground 6.

  The heat pump 4 includes a water-cooled heat exchanger 5 and an air-cooled heat exchanger 8. The heat pump 4 is connected to a medium flow path 9 that is connected to the air conditioner 3 and constitutes a heat exchange medium circulation path. Examples of the heat exchange medium circulating in the medium flow path 9 include well-known scientific refrigerants such as CFC, HCFC, and HFC systems, or cold water and hot water. The heat pump 4 switches the electromagnetic valve (not shown) according to the operation status, thereby selectively guiding the heat exchange medium to the water-cooled heat exchanger 5 and the air-cooled heat exchanger 8 to exchange heat by water cooling and air cooling. To do. In this embodiment, an antifreeze is used as the cooling water. In this embodiment, the heat pump 4 is exemplified by a hybrid system having a water-cooled heat exchanger 5 and an air-cooled heat exchanger 8, but is a known water-cooled heat pump having only the water-cooled heat exchanger 5. Also good.

  On the heat collecting pipe 7, a circulation pump 10 that circulates the cooling water in the heat collecting pipe 7, a flow meter 11 that measures the flow rate of the cooling water flowing in the heat collecting pipe 7, and the flow rate of the cooling water that flows in the heat collecting pipe 7. A flow rate adjusting valve 12 to be adjusted and an expansion tank 13 that allows increase and decrease due to a temperature change of the cooling water are provided. One end 7 a of the heat collection pipe 7 is connected to the suction side of the circulation pump 10 via the water-cooled heat exchanger 5, and the other end 7 b is discharged from the circulation pump 10 via the expansion tank 13, the flow rate adjustment valve 12, and the flow meter 11. Connected to the side. In FIG. 1, reference numeral 70 indicates a flow path for introducing the cooling water heat-exchanged by the water-cooled heat exchanger 5 into the underground 6, and reference numeral 71 indicates the water-cooled cooling water heat-exchanged in the underground 6. The flow path returning to the heat exchanger 5 is shown. In this embodiment, the flow path system including the heat collecting pipe 7 and the circulation pump 10 is configured as a closed circuit, but may be an open circuit.

  In the underground heat system 1, when the air conditioner 3 is powered on, the circulation pump 10 is first driven to perform heat exchange using the water-cooled heat exchanger 5. When predetermined conditions are met, the circuit is switched by an electromagnetic valve (not shown), the heat exchange medium is introduced into the air-cooled heat exchanger 8, and the heat exchange medium is heat-exchanged by air cooling. The circuit switching by the electromagnetic valve may be switched so that a heat exchange medium is introduced into the air-cooled heat exchanger 8 and introduced into the water-cooled heat exchanger 5 when a predetermined condition is met.

  The heat collection tube 7 is made of a resin such as polyethylene or cross-linked polyethylene, and is wound in a loop shape having a diameter of about 1 meter on the ground, and the loop shape is shifted in the horizontal direction. The loop portion 7C is held in a state shifted in the horizontal direction by a restraining member (not shown).

  In the land in the site where the geothermal system 1 is introduced, a hole 20 in which the heat collecting pipe 7 held with the loop portion 7C being shifted is vertically embedded is excavated. In the hole 20, the loop portion 7C of the heat collecting tube 7 is embedded so as to be in a vertical state. Around the embedded loop portion 7C, in order to increase the heat exchange efficiency of the loop portion 7C, the first portion is filled with sand or the like having a height H1 from the bottom 20a of the hole 20 until the loop portion 7C is filled. Layer 31 is formed. The upper part of the first layer 31 is filled with sand or the like to fill the second layer 32 having the second height H2 and the generated soil generated when excavating from the second layer 32 to the ground surface. A third layer 33 having a height H3 is formed. The total length L of the hole 20 is set to a length that can accommodate the entire loop portion 7C. As shown in FIG. 2, the entire width W of the hole 20 is such that the loop portion 7C is formed to be somewhat wider than the thickness W1.

  In the geothermal system 1 having such a configuration, when the power of the indoor device 3 is turned on, the indoor device 3 operates and the circulation pump 10 operates. When the indoor device 3 operates, the heat exchange medium is circulated between the water-cooled heat exchange device 5 through the medium flow path 9 and cooling or heating is performed. When the circulation pump 10 is operated, the cooling water moves through the heat collection pipe 7 and is guided to the water-cooled heat exchange device 5. Then, heat exchange is performed with the heat exchange medium by the water-cooled heat exchange device 5. The heat-exchanged cooling water is guided to the loop portion 7 </ b> C embedded in the underground 6, is heat-absorbed or dissipated in the underground and is heat-exchanged, and is returned to the water-cooled heat exchange device 5. When the underground heat system 1 is in a predetermined condition, the heat exchange medium introduced into the water-cooled heat exchange device 5 by operating an electromagnetic valve (not shown) is introduced into the air-cooled heat exchanger 8, Heat exchanged.

  Since the hole 20 excavated in the underground 6 is a hole excavated so that the loop portion 7C of the heat collecting tube 7 wound in a loop shape can be embedded vertically, the width W of the hole 20 to be excavated is the thickness of the heat collecting tube 7. The direction width W1 + α is sufficient, and the excavation area and the amount of earth and sand to be dug are reduced. For this reason, since the construction which embeds the heat collecting pipe 7 can be performed even in a densely populated area or a narrow area where there is little space in the horizontal direction, the low-cost underground heat system 1 can be provided. In addition, since the amount of earth and sand to be dug is reduced, the place for the earth and sand to be dug (generated earth) may be narrow, and the cost can be further reduced.

The amount of backfill soil (generated soil) in the case where the loop portion of the heat collecting tube is buried horizontally and the case where it is buried vertically will be described under the following conditions. FIG. 3A shows a hole 30 for horizontally embedding the loop portion of the heat collecting tube, and FIG. 3B shows a hole 20 for embedding the loop portion of the heat collecting tube vertically.
Diameter of heat collection tube 25mm
Loop diameter 1000mm
Loop pitch 200mm
Number of loops 26 windings Overall length of loop part 6050mm
Total length of hole 6100mm
Thickness width W1 250mm
Second layer height 500mm
Third layer height 500mm

(For horizontal burial)
As shown in FIG. 3 (a), when the height H1 of the first layer from the bottom 30a of the hole 30 until the loop portion is filled is 300 mm, the depth 30H of the hole 30 is increased from the first layer to the third level. The sum of the layers is 1300 mm, and the amount of generated soil T1 is obtained by Equation 1.
T1 = total length 6100 mm × width 1000 mm × depth 1300 mm Formula 1
Therefore, T1 = 7.93 m ³

(For vertical burial)
As shown in FIG. 3B, assuming that the height H1 of the first layer until the loop portion from the bottom 20a of the hole 20 is filled is 1000 mm, the depth 20H of the hole is the third depth from the first layer. The sum of the layers is 2000 mm, and the generated soil amount T2 is obtained by Equation 2.
T2 = total length 6100 mm × width 300 mm × depth 2000 mm. Formula 2
Therefore, T2 = 3.66 m ³

That is, upon embedding the Tonetsukan 7, in either a loop portion 7C buried or vertically embedded horizontally, dig up earth and sand amount of 7.93m ³ -3.66m ³ = 4.27m ³ of (waste soil) There is a difference, and a difference of about 2.2 times occurs. This difference is the difference in the size of the soil that has been dug up.

Next, the amount of sand used for the first layer 31 and the second layer 32 will be described. The amount of sand is calculated without considering the volume of the loop portion 7C in the first layer 32.
(For horizontal burial)
The amount T3 of sand or the like used for the first layer and the second layer is obtained by Equation 3.
T3 = total length 6100 mm × width 1000 mm × depth 800 mm ... Equation 3
Therefore, T3 = 4.88 m ³
(For vertical burial)
The amount T4 of sand used for the first layer and the second layer is obtained by Equation 4.
T3 = total length 6100 mm × width 300 mm × depth 1500 mm ... Equation 4
Therefore, T2 = 2.75 m ³

That is, when the heat collecting tube 7 is embedded, whether the loop portion 7C is embedded horizontally or vertically, the amount of sand used for the first layer 31 and the second layer 32 is 4.88 m ³ −. There is a difference of 2.75 m ³ = 2.13 m ^{3 and} a difference of about 1.8 times occurs. This difference appears as a cost difference as it is.

Next, the amount of generated soil to be backfilled in the third layer will be described.
(For horizontal burial)
The amount T5 of the generated soil to be backfilled in the third layer is obtained by Expression 5.
T5 = Overall length 6100 mm × Width 1000 mm × Search 500 mm Formula 5
T3 = 3.05m ³
Since the total amount of soil dug up is 7.93 m ³ ,
The generated soil of 7.93 m ³ −3.05 m ³ = 4.88 m ³ becomes the remaining soil.

(For vertical burial)
The amount T6 of the generated soil to be backfilled in the third layer is obtained by Expression 6.
T5 = total length 6100 mm × width 300 mm × depth 500 mm...
T3 = 0.915m ³
Since the total amount of soil dug up is 3.66 m ³ ,
3.66m ³ -0.915m ³ = occurrence soil of about 2.75m ³ is the residual soil.

That is, upon embedding the Tonetsukan 7, in either a loop portion 7C buried or vertically embedded horizontally, there is a difference of 4.88m ³ -2.75m ³ = 2.13m ³ to residual soil amount, approximately 1 A difference of 8 times occurs. This difference is the difference in the processing cost of the remaining soil as it is.

  It is a schematic block diagram which shows the underground heat system which is one form of this invention, and the embedding method of the heat collection pipe | tube used for this system.   It is the schematic which planarly viewed the state of the underground heat system and the heat collecting pipe embed | buried under the ground.   (A) shows the hole which embeds a heat collecting pipe horizontally, (b) is a figure showing the hole which embeds a heat collecting pipe vertically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Geothermal system 5 Heat exchanger 6 Underground 7 Heat collection pipe 7C Loop part 20 of a heat collection pipe

Claims (2)

In the method of burying the heat collecting pipe used in the underground heat system connected to the heat exchanger and transporting the cooling medium heat exchanged by the heat exchanger to the ground to exchange heat,
The heat collection tube is wound in a loop shape to excavate a hole that can be embedded vertically, and the loop portion of the heat collection tube is shifted horizontally in the excavated hole so that the loop portion is in a vertical state. A heat collecting pipe burying method used in a geothermal system, wherein the heat collecting pipe is buried. In the underground heat system that is connected to the heat exchanger and exchanges heat by transporting the cooling medium heat exchanged by this heat exchanger to the ground with a heat collection pipe,
An underground heat system, wherein the heat collection tube is embedded by the burying method according to claim 1.

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