JP6018983B2 - Geothermal heat exchanger for geothermal heat pump system - Google Patents

Description

  The present invention relates to a geothermal heat pump system, and more particularly to a geothermal heat exchanger embedded in a direction perpendicular to the ground.

  A geothermal heat pump system is a system that pumps heat, that is, a system that moves heat from a low temperature to a high temperature. In winter, the ground heat that is warmer than the outside air is collected and used for indoor heating and the like, and in summer, the heat is thrown away into the ground where the temperature is lower than the outside air to increase the cooling efficiency of the room.

  The geothermal heat pump system uses geothermal heat, which is a kind of renewable energy, and can not only perform heating and cooling using the same heat pump device, but also extract heat energy several times the input energy. It has various advantages such as reducing CO2 emissions during heating and reducing power consumption during cooling. The system configuration includes a ground heat exchanger (primary system) and a heat pump device (heat source equipment) System) and an indoor unit (secondary system) (Patent Document 1).

  The present invention is a technology related to a ground heat exchanger (primary system). The underground heat exchanger (primary system) that circulates fluid for sampling and exhausting heat (for heat exchange) has various configurations. Broadly divided into a horizontal burying mold and a vertical burying mold, the present invention relates to a vertical burying mold.

  The geothermal heat pump system in Japan often adopts a vertical buried type called the borehole system. As shown in FIG. 11, a conventional borehole type geothermal heat pump system is provided with a drilling hole perpendicular to the ground in order to cool and heat a house 5, for example, and a U-shaped tube tube 7 is provided in the drilling hole. After paying, fill the excavation hole with soil and make a ground heat exchanger.

  Then, the heat for collecting and exhausting heat (for example, water and antifreeze liquid) inside the U-shaped tube tube 7 is circulated through the heat pump device 2, the heat energy is transferred in the heat pump device 2, and the indoor unit 3 is Air conditioning / heating.

  Since heat is collected in the winter and in the summer, the heat is discharged into the ground through a fluid for heat extraction (such as water and antifreeze) that circulates inside the U-shaped tube 7. It is preferable that the working fluid flows inside the U-shaped tube tube 7 for as long as possible. For this reason, conventionally, the depth H1 of the excavation hole is usually set to 100 to 150 m.

JP2013-007551A

  By the way, the penetration rate of geothermal heat pump systems in Japan is very low compared to other countries in Europe and the United States. The reason is as follows.

  First, in the case of the borehole method, the amount of heat that can be taken out from the U tube used as an underground heat exchanger is small, so that the excavation depth needs to be about 100 to 150 m.

  Secondly, the excavation cost is high (for example, 10,000 yen / 1 m).

  Thirdly, industrial waste such as residual soil is generated along with excavation, resulting in increased processing costs.

  In particular, the high cost of excavation is a major cause that hinders its spread. In large-scale condominiums and office buildings, etc., it is necessary to provide multiple drilling holes with a depth of over 100 m. This is because there are many cases that hesitate to introduce.

  Therefore, an object of the present invention is to further reduce the installation cost of a borehole type underground heat exchanger that is buried perpendicularly to the ground.

  In order to achieve the above-mentioned object, the underground heat exchanger according to the present invention circulates through the heat pump device on the technical premise of the underground heat exchanger for the underground heat pump system embedded perpendicularly to the ground. A metal buried pipe for temporarily storing the waste heat fluid, a fluid feed pipe for feeding the collection and exhaust heat fluid to the buried pipe via a heat pump device, and a collection and exhaust heat fluid inside the buried pipe. A fluid delivery pipe for reflux to the heat pump device, and a metal spiral blade projecting outwardly and fixed to the outer peripheral surface of the buried pipe, and the lateral width of the spiral blade is set to The dimension is set to 2 to 3 times the outer diameter (Claim 1).

  Since the underground heat exchanger according to the present invention includes a metal spiral blade on the outer periphery of the buried pipe, the contact area in the ground is expanded.

  For this reason, the efficiency of heat collection / exhaust heat (radiation) of the fluid for collecting and exhausting heat can be improved substantially in proportion to the area of the spiral blade, and even when the embedment depth of the buried pipe is reduced, preferable sampling is performed. Heat / waste heat can be performed. Since the width of the metal spiral blade according to the present invention is set to a dimension that is two to three times the outer diameter of the buried pipe, the area of the spiral blade is small even when the total outer peripheral area of the buried pipe is small. To achieve sufficient heat exchange.

  The problem with the borehole type underground heat exchanger was that the cost associated with ground excavation was high, so by realizing sufficient heat exchange even when the buried pipe depth was shallow, the underground heat pump system The introduction cost can be reliably reduced.

  Moreover, since the underground heat exchanger which concerns on this invention equips the outer peripheral surface of a buried pipe with a spiral blade board, it is not necessary to bury a buried pipe after providing an excavation hole in the ground. This is because the buried pipe can be rotated and penetrated using a spiral blade. In the case of rotational penetration, the construction cost required for vertical excavation of the ground can be greatly reduced.

  The spiral blade may include a plurality of dimples or small convex portions on at least one of the upper surface and the lower surface (Claim 2).

  When the areas of the spiral blades are the same, a plurality of dimples (small concave portions) are provided on the upper surface / lower surface of the spiral blade plate, or a plurality of small convex portions (for example, a cross section) are provided on the upper surface / lower surface of the spiral blade plate. By providing a circular arc), it is possible to increase the contact area in the ground, and it is possible to further increase the efficiency of heat collection / exhaust heat (radiation) of the collection / exhaust heat fluid.

  In some cases, an embedded hollow auxiliary pipe is fixedly provided at the upper end of the buried pipe, and the buried auxiliary pipe is provided under the ground.

  By providing an internal hollow buried auxiliary pipe at the upper end of the buried pipe, the buried auxiliary pipe can be rotated through a motor device attached to a work machine such as a power shovel. For this reason, the embedment depth of the buried pipe can be freely set according to the vertical dimension of the buried auxiliary pipe.

  The temperature below the ground is usually stable at a shallow depth below the ground, for example, about 5 to 10 m. For this reason, according to climatic conditions etc., it becomes possible to implement | achieve the embedding depth which can suppress installation cost most by adjusting the depth of an embedding pipe via an embedding auxiliary pipe. In order to prevent unnecessary heat loss, the buried auxiliary pipe is also buried under the ground, and the fluid feed pipe and the fluid delivery pipe to be drawn out from the upper end of the buried auxiliary pipe are also buried under a predetermined length below the ground. It is desirable to do.

  According to the underground heat exchanger which concerns on this invention, it becomes possible to further reduce the installation cost of the underground heat exchanger embed | buried perpendicularly | vertically with respect to the ground.

It is sectional drawing which illustrates the underground heat exchanger which concerns on embodiment. It is a perspective view which illustrates the appearance of an embedding pipe concerning an embodiment. It is a figure which illustrates 2nd embodiment of the spiral blade board which concerns on this invention. It is a figure which illustrates 3rd embodiment of the spiral blade board which concerns on this invention. It is a figure which illustrates the example of embedding of the buried pipe which concerns on this invention. It is a figure which illustrates the burial auxiliary pipe concerning the present invention. It is a figure which illustrates the joint member concerning the present invention. It is a figure which shows the example of a connection of the buried pipe and the buried auxiliary pipe through the joint member shown in FIG. It is a figure which illustrates the extension state of the fluid inflow tube and fluid delivery tube in FIG. It is a figure which illustrates the embedding state at the time of using the embedding auxiliary pipe | tube which concerns on this invention. It is a figure which illustrates the conventional geothermal heat pump system.

  As shown in FIG. 1, the underground heat exchanger 10 according to the present invention includes a metal buried pipe 11 that temporarily stores a heat extraction fluid R to be circulated through the heat pump device 2, and a heat pump device 2. A fluid feed pipe 14 for feeding the sampling / exhaust heat fluid R into the buried pipe 11 and a fluid delivery pipe 15 for returning the collection / exhaust heat fluid R inside the buried pipe 11 to the heat pump device 2. A metal spiral blade 20 is provided on the outer peripheral surface of the tube 11. This underground heat exchanger 10 has a spiral blade 20 fixed in advance in a factory.

  The buried pipe (main pipe) 11 is made of metal, for example, a steel pipe. Since the buried pipe 11 is for temporarily storing the sampling / exhaust heat fluid R and performing heat exchange (sampling / exhaust heat) with the underground heat, the lower end and the upper end are appropriately closed using a material. . By using a sealed tube with a bottom and a lid, the fluid R for collecting and exhausting heat is stored in the embedded tube 11 via the fluid inlet tube 14 and the fluid outlet tube 15, and the heat pump device 2 performs heat exchange. Circulate between.

  It is desirable to rust the inner surface of the buried pipe 11. For example, plating treatment, coating with a rust preventive material, or providing a resin-molded cylindrical inner material. The vertical dimension H2 of the buried pipe 11 can be set to about 5 to 15 m, for example. Preferably, a steel pipe of 5.5 to 6 m is used.

  A resin pipe or a metal pipe is used for the fluid inlet pipe 14 and the fluid outlet pipe 15.

  It is desirable that the lower end opening of the fluid inlet pipe 14 is disposed near the bottom of the buried pipe 11. This is for fluidizing and agitating the sampling and exhaust heat fluid R of the buried pipe 11 to equalize heat exchange with the underground heat.

  The fluid delivery pipe 15 is disposed at an appropriate position of the buried pipe 11, for example, near the upper part. This is because the heat for collecting and exhausting heat R stored for a while in the buried pipe 11 is fluidized and stirred, so that the temperature is equalized. As the fluid for collecting and exhausting heat R, an appropriate fluid such as water, antifreeze liquid, refrigerant or the like can be used.

  The spiral blade 20 is made of metal, and transmits the underground heat to the metal buried pipe 11 at the time of heating in winter and functions to take the heat of the buried pipe 11 and exhaust the heat to the ground at the time of cooling in summer. The metal spiral blade 20 can be formed using, for example, a long metal plate (flat plate) having an appropriate thickness. As the metal plate, for example, a steel plate can be used.

  The spiral blade 20 is fixed so that the tip protrudes outward from the buried tube 11. The inner peripheral base end portion of the spiral blade 20 is fixed to the outer peripheral surface of the buried pipe 11 by appropriate means, for example, welding.

  In order to enhance the effect of heat collection or exhaust heat, as shown in FIG. 2, the protrusion amount W2 of the spiral blade plate 20 is increased with respect to the outer diameter W1 of the buried pipe 11, or the pitch of the spiral blade plate 20 is increased. Increase the number of wings by narrowing. These conditions are preferably set according to the climatic conditions of the land where the underground heat exchanger 10 is installed, the usage environment (operating capacity of the heat pump device), etc., but at least the amount of protrusion of the spiral blade 20 (width) ) W2 is set to 1.5 to 3.5 times the outer diameter W1 of the buried pipe 11. This is to ensure the effect of heat collection / exhaust heat (heat radiation) through the spiral blade plate 20. At the time of implementation, it is desirable that the protrusion amount (lateral width) W2 of the spiral blade 20 is about 2 to 3 times the outer diameter W1 of the buried pipe 11.

  Therefore, according to the underground heat exchanger 10, the metal spiral blade 20 increases the contact area in the ground and enhances the heat collection / exhaust heat effect of the buried pipe 11.

  As a result, even if the vertical dimension H2 of the buried pipe 11 is reduced, the heat extraction fluid R inside the buried pipe 11 can perform sufficient heat exchange, and the conventional borehole type underground heat exchange is possible. Compared to a vessel, heat exchange efficiency can be achieved at a much shallower depth.

  Instead of using a thin U-tube as in the prior art, if the buried heat 11 is circulated while temporarily storing it using the buried pipe 11 having a certain inner diameter, heat collection through the spiral blade 20 is performed. / Additional effect of exhaust heat enables underground heat exchange at shallower depths.

  For this reason, if the vertical dimension of the buried pipe 11 is set to 5 to 15 m, heat exchange efficiency corresponding to a conventional borehole type underground heat exchanger using a U tube and having a depth of 100 to 150 m can be obtained. Since the burial depth can be reduced, the installation cost is surely reduced.

  Further, by providing the spiral blade 20 on the outer peripheral surface of the buried pipe 11, it is not necessary to provide a bore hole (excavation hole) when the buried pipe 11 is buried. This is because the spiral wing plate 20 performs the same function as the screw, so that the buried pipe 11 can be rotated and penetrated perpendicularly to the ground. For this reason, the economic burden conventionally required for excavation can be greatly reduced.

  The underground heat exchanger according to the present invention is not limited to that of the above embodiment. For example, as shown in FIG. 3, a plurality of small dimples (small concave portions) 31 may be formed on the surface (upper surface / lower surface / both surfaces) of a metal plate (flat plate) P used as the spiral blade plate 20. This is because the contact area in the ground increases due to the formation of the dimple 31 when the entire area is the same.

  Similarly, a plurality of small convex portions 33 may be formed (see FIG. 4). This is because, when the entire area of the spiral blade 20 is the same, the contact area increases due to the formation of the small protrusions 33. The small convex part 33 can be made into the small protrusion of a cross-sectional arc shape, for example. When the embedded tube 11 is rotated and penetrated, it is desirable that the small convex portion 33 is disposed on the upper surface of the spiral blade plate 20 so as not to obstruct the penetration.

  In order to increase the embedding depth of the buried pipe 11, an auxiliary member that supports the rotation penetration of the buried pipe 11 may be provided on the buried pipe 11.

  5 to 10 illustrate a burying method in which a buried auxiliary pipe 30 as an auxiliary member is provided on the buried pipe 11, and the buried pipe 11 is rotated and penetrated below the ground.

  In this case, when the buried pipe 11 is rotated and penetrated below the ground, first, as shown in FIG. 5, the ground surface GL is slightly dug to create a work surface GL2, and the buried pipe 11 is rotated and penetrated vertically from the work surface GL2. Let The work surface GL2 is formed by digging the ground surface GL, for example, by about 0.5 to 2 m. In general, the amount of digging is desirably about 1 m.

  In this state, the earth and sand dug down after connecting the fluid inlet pipe 14 and the fluid outlet pipe 15 to the heat pump device 2 may be backfilled, but when the vertical dimension of the buried pipe 11 is about 5 to 6 m. Since the burial depth of the burial pipe 11 is slightly shallower, preferably, as shown in FIG. 6, an inner hollow burial auxiliary pipe 30 is fixedly provided at the upper end portion of the burial pipe 11, and the burial auxiliary pipe 30 is rotated. By doing so, the buried pipe 11 is buried in deeper underground.

  As the buried auxiliary pipe 30, for example, a steel pipe can be used. Unlike the buried pipe 11, it does not fill the fluid inside. Therefore, if not particularly necessary, the rust prevention treatment may not be performed. The buried auxiliary pipe 30 penetrates the upper end portion to the vicinity of the work surface GL2.

  The connection between the upper end portion of the buried pipe 11 and the lower end portion of the buried auxiliary pipe 30 can be performed by appropriate means such as welding and bolting.

  FIG. 7 shows an example of the connection between the buried pipe 11 and the buried auxiliary pipe 30. For example, a metal joint member 42 is provided at the upper end of the buried pipe 11, and the buried pipe 11 is interposed via the joint member 42. And the buried auxiliary pipe 30 are connected.

  The joint member 42 is formed into a thick disk shape having an outer diameter that can be fitted into the buried pipe 11. For example, the joint member 42 is provided with the fluid inlet pipe 14 and the fluid outlet pipe 15, longitudinal guide holes 44 and 45 for guiding the fluid upward, and a lateral bolt hole 36.

  As shown in FIG. 8, after installing the joint member 42 on the upper end portion of the buried pipe 11, the buried auxiliary pipe 30 is placed on the buried pipe 11, and the bolt B is screwed into the bolt hole 36. The buried pipe 11 and the buried auxiliary pipe 30 are connected and fixed. The number of bolt holes 36 may be increased or decreased as appropriate.

  Further, as shown in FIG. 9, the fluid inlet pipe 14 and the fluid outlet pipe 15 included in the buried pipe 11 are extended upward using guide holes 44 and 45. The fluid inlet tube 14 and the fluid outlet tube 15 may be extended via appropriate pipe joints (not shown).

  Therefore, according to such a configuration, the buried pipe 11 is rotated and penetrated into the ground from the work surface GL2, and then the buried auxiliary pipe 30 is provided on the buried pipe 11, so that the buried pipe 11 is further rotated and penetrated deeper. It becomes possible.

  Thereafter, the fluid inlet pipe 14 and the fluid outlet pipe 15 are connected to the heat pump device 2 using an appropriate connecting pipe, and the excavation step between the work surface GL2 and the ground surface GL is backfilled to install the geothermal exchanger. Exit.

  In this way, for example, when the vertical dimension of the buried pipe 11 is 5 m, the vertical dimension of the buried auxiliary pipe 30 is 4 m, and the vertical dimension of the backfill is 1 m, the buried pipe 11 is buried from the ground surface GL as shown in FIG. The vertical dimension D to the lower end of the pipe 11 is 10 m, and the entire buried pipe 11 is buried at a position below 5 m below the ground, which is a stable temperature zone of underground heat.

  As described above, by providing the burial auxiliary pipe 30, the burial pipe 11 can be buried freely at a relatively shallow depth, and efficient heat exchange by heat collection / radiation via the spiral blade plate 20 can be performed. .

  The number of the buried auxiliary pipes 30 is not limited to one. After providing the buried auxiliary pipe 30 on the buried pipe 11, a second-stage buried auxiliary pipe (30) may be provided on the buried auxiliary pipe 30. This is to adjust the embedding depth of the embedding pipe 11. The third stage buried auxiliary pipe (30) may be connected and fixed on the second stage buried auxiliary pipe (30). The number of burial auxiliary pipes (30) is not limited. The connection between the buried auxiliary pipes (30) can be appropriately performed, for example, through the joint member (42).

DESCRIPTION OF SYMBOLS 2 Heat pump apparatus 10 Ground heat exchanger 11 Buried pipe 14 Fluid inflow pipe 15 Fluid delivery pipe 20 Spiral blade 30 Buried auxiliary pipe 31 Dimple (small recessed part)
33 Small convex portion 36 Bolt hole 42 Joint member 44, 45 Guide hole GL Ground surface GL2 Work surface H2 Vertical dimension of buried pipe R Heat extraction fluid W1 Outer diameter of buried pipe W2 Projection amount of spiral blade

Claims (2)

In the underground heat exchanger for the underground heat pump system buried vertically in the ground,
A metal buried pipe for temporarily storing a fluid for collecting and exhausting heat to be circulated through a heat pump device;
A buried auxiliary pipe fixed to the upper end of the buried pipe;
A fluid inlet tube feeding the Tohai thermal fluid into the buried pipe through the heat pump device,
Provided with a fluid delivery tube for recirculating the interior of the adoption waste heat fluid of the buried pipe to the heat pump device,
A metal spiral blade is protruded outward and fixed to the outer peripheral surface of the buried pipe,
The lateral width of the spiral blade is set to 1.5 to 3.5 times the outer diameter of the buried pipe ,
The buried auxiliary pipe is
A geothermal heat exchanger for a geothermal heat pump system, which adjusts the embedment depth of the buried pipe and does not fill the inside of the heat for collecting and exhausting heat . The spiral vane
At least one of the upper surface and the lower surface,
The ground heat exchanger for a geothermal heat pump system according to claim 1, comprising a plurality of dimples or small convex portions.

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