JP2010145032A - Underground heat exchanger and air conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground heat exchanger capable of reducing cost and weight while sufficiently securing the strength of an outer pipe. <P>SOLUTION: The outer pipe (30) embedded in the ground includes: metallic piping (31) which is made of metal and has closed pipe ends and inside of which a heating medium is filled; and a reinforcement layer (32) formed of mortar (32b) having reinforcement wire rods (32a) arranged therein and covering the outer peripheral face of the metallic piping (31). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground heat exchanger for exchanging heat between a heat exchange fluid and soil in the ground, and an air conditioning system using the same.

  2. Description of the Related Art Conventionally, underground heat exchangers that exchange heat between a heat exchange fluid and underground soil via a sealed heat medium are known. This underground heat exchanger is used in, for example, a refrigerant circuit that performs a refrigeration cycle. Patent Document 1 discloses a ground heat exchanger that heats a refrigerant (heat exchange fluid) in a refrigerant circuit using ground heat in heating operation.

  The underground heat exchanger of patent document 1 is comprised with the double pipe type heat exchanger which consists of an outer tube | pipe and the inner tube inserted inside this outer tube | pipe. The inner pipe is closed at both ends to form a sealed space inside. The heat medium is sealed in the sealed space. The outer pipe has a refrigerant passage through which the refrigerant in the refrigerant circuit flows.

  And the said inner pipe is being fixed to the pipe inner side of an outer pipe | tube so that the upper and lower ends may protrude from the inner side of an outer pipe | tube to a pipe-axis direction. The inner pipe protruding downward from the outer pipe is buried in the ground so that the pipe axis direction of the inner pipe is along the vertical direction. That is, the lower part of the inner pipe is in contact with the soil in the ground, and the upper part of the inner pipe is in contact with the refrigerant flowing through the refrigerant passage of the outer pipe.

In such a configuration, when a refrigerant having a temperature lower than that in the ground is circulated through the refrigerant flow path, the heat medium vapor having the equilibrium vapor pressure at the underground temperature and the refrigerant passage of the outer pipe flow above the inner pipe. The heat medium is condensed by exchanging heat with the cold refrigerant, and the refrigerant is heated by the heat of condensation. The cold heat medium condensed and liquefied descends from the upper side to the lower side in the inner tube. At the lower end side of the inner pipe, the soil in the ground and the heat medium exchange heat, and the heat medium is evaporated so as to have a vapor pressure that is in equilibrium with the underground temperature. The evaporated heat medium rises again in the inner tube from the lower end side toward the upper end side. That is, the inner pipe becomes a heat pipe, and the refrigerant in the refrigerant pipe can be heated by underground heat.
International Publication No. WO2004 / 111559 Pamphlet

  By the way, in recent years, from the viewpoint of preventing global warming, it is considered to use carbon dioxide as a heat medium in place of the HFC refrigerant. However, when carbon dioxide is used as the heat medium, the internal pressure of the outer tube increases due to the high operating pressure range, and it is necessary to employ a tube structure that can withstand this internal pressure. Therefore, measures such as configuring the outer pipe with a high-pressure steel pipe or increasing the wall thickness of the outer pipe can be considered, but the weight of the outer pipe increases, making it difficult to carry and handle, and cost. There was a problem of increasing.

  This invention is made | formed in view of this point, The objective is providing the underground heat exchanger which can aim at cost reduction and weight reduction, ensuring the intensity | strength of an outer tube | pipe enough. is there.

  In order to achieve the above-described object, the present invention can ensure sufficient strength as a whole outer pipe even when the metal pipe constituting the outer pipe is thinned by devising the configuration of the outer pipe. did.

  Specifically, the present invention relates to an outer pipe (30) embedded in the ground so that the pipe axis direction is along the vertical direction, and is inserted into the pipe of the outer pipe (30) and has a heat exchange fluid inside. The following solution was taken for the underground heat exchanger with the inner pipe (20) through which the water flows.

  That is, according to the first aspect of the present invention, the outer pipe (30) has a metal metal pipe (31) in which a pipe end is closed and a heat medium is enclosed inside, and a reinforcing wire (32a) inside. And a reinforcing layer (32) configured by the mortar (32b) and covering the outer peripheral surface of the metal pipe (31).

  In the first invention, the outer pipe (30) includes a metal pipe (31) made of metal and a reinforcing layer (32) that covers the outer peripheral surface of the metal pipe (31). The pipe end of the metal pipe (31) is closed, and the heat medium is sealed inside. The reinforcing layer (32) is composed of a mortar (32b) in which a reinforcing wire (32a) is disposed.

  With such a configuration, even if the thickness of the metal pipe (31) is reduced in order to reduce the weight of the outer pipe (30), the strength of the outer pipe (30) as a whole is increased by the reinforcing layer (32). It can be secured sufficiently. For this reason, the outer tube (30) should have a tube structure that can withstand the internal pressure even when carbon dioxide, whose internal pressure in the outer tube (30) increases due to the high operating pressure range, is used as the heat medium. Can do.

  In addition, since insulation can be improved by covering the metal pipe (31) with mortar (32b), it is possible to prevent the metal pipe (31) from being energized when a lightning strike occurs, and the underground heat exchanger (10) It is possible to prevent damage to itself and the heat pump equipment. Furthermore, by covering with mortar (32b), the outer diameter of the outer tube (30) can be increased, the heat transfer area can be increased, and the heat exchange capacity is improved.

  Further, if the metal pipe (31) is covered with a waterproof mortar (32b), it is possible to prevent rainwater or the like from entering the ground and rusting the metal pipe (31). If the metal pipe (31) is covered with mortar (32b) with high thermal conductivity, heat can be absorbed efficiently from the soil in the ground into the underground heat exchanger (10). Exchange ability is improved.

According to a second invention, in the first invention,
The reinforcing layer (32) includes a plurality of flange portions (33) projecting radially outward from the outer peripheral surface of the metal pipe (31) and arranged at predetermined intervals in the tube axis direction. It is characterized by.

  In the second invention, the plurality of flange portions (33) constituting the reinforcing layer (32) project radially outward from the outer peripheral surface of the metal pipe (31) and are arranged at predetermined intervals in the tube axis direction. Is done. If it is set as such a structure, the intensity | strength as the whole outer pipe | tube (30) can further be raised by providing a flange part (33) in a reinforcement layer (32). Therefore, even if the thickness of the mortar (32b) constituting the reinforcing layer (32) is reduced, the strength of the outer tube (30) can be sufficiently secured, which is advantageous for further weight reduction.

According to a third invention, in the first or second invention,
The reinforcing layer (32) includes a linear member (34) wound in the circumferential direction along the outer peripheral surface of the metal pipe (31).

  In 3rd invention, the linear member (34) which comprises a reinforcement layer (32) is wound in the circumferential direction along the outer peripheral surface of metal piping (31). With such a configuration, the overall strength of the outer pipe (30) can be further increased by winding the linear member (34) around the metal pipe (31). Therefore, even if the thickness of the mortar (32b) constituting the reinforcing layer (32) is reduced, the strength of the outer tube (30) can be sufficiently secured, which is advantageous for further weight reduction.

  A fourth invention is a refrigerant circuit that performs a vapor compression refrigeration cycle by connecting a compressor (5), a heat source side heat exchanger (10), an expansion mechanism (6), and a use side heat exchanger (7). The following solutions were taken for air conditioning systems equipped with (1).

  That is, in the fourth invention, the inner pipe (20) of the underground heat exchanger (10) according to any one of the first to third inventions is connected to the refrigerant circuit (1). Thus, the heat source side heat exchanger (10) is constituted by the underground heat exchanger (10).

  In the fourth invention, in the air conditioning system, the underground heat exchanger (10) can be used as the heat source side heat exchanger (10) in the vapor compression refrigeration cycle. With such a configuration, when the air conditioning system is a heating device, the underground heat exchanger (10) serves as an evaporator and the use side heat exchanger (7) serves as a condenser. In this underground heat exchanger (10), the low-pressure refrigerant that has flowed out of the expansion mechanism (6) exchanges heat with the soil in the ground, and the low-pressure refrigerant absorbs heat from the soil in the ground. Can be evaporated.

  On the other hand, when the air conditioning system is a cooling device, the underground heat exchanger (10) serves as a condenser and the use side heat exchanger (7) serves as an evaporator. In this underground heat exchanger (10), the high-pressure refrigerant discharged from the compressor (5) exchanges heat with the soil in the ground, and the high-pressure refrigerant dissipates heat to the soil in the ground. Can be condensed.

  According to the present invention, even if the thickness of the metal pipe (31) is reduced in order to reduce the weight of the outer pipe (30), the strength of the outer pipe (30) as a whole is sufficiently increased by the reinforcing layer (32). Can be secured. For this reason, the outer tube (30) should have a tube structure that can withstand the internal pressure even when carbon dioxide, whose internal pressure in the outer tube (30) increases due to the high operating pressure range, is used as the heat medium. Can do.

  Further, if the metal pipe (31) is covered with a waterproof mortar (32b), it is possible to prevent rainwater or the like from being immersed in the ground and the metal pipe (31) from being rusted. If the metal pipe (31) is covered with mortar (32b) with high thermal conductivity, heat can be absorbed efficiently from the soil in the ground into the underground heat exchanger (10). Exchange ability is improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

<Configuration of air conditioning system>
FIG. 1 is a refrigerant circuit diagram of an air conditioning system using a ground heat exchanger according to an embodiment of the present invention. As shown in FIG. 1, this air conditioning system (A) comprises the heating apparatus which heats a room | chamber interior using the underground heat, and is provided with the refrigerant circuit (1).

  The refrigerant circuit (1) includes a compressor (5), an expansion valve (6) as an expansion mechanism, an indoor heat exchanger (7) as a use side heat exchanger, and a ground as a heat source side heat exchanger. The intermediate heat exchanger (10) is connected to the refrigerant pipe (1a).

  Here, the underground heat exchanger (10) is buried in the ground, and the indoor heat exchanger (7) is installed indoors. If there is a machine room in the basement, the machine room contains element equipment other than the indoor heat exchanger (7) and underground heat exchanger (10) in the air conditioning system (A), that is, the compressor (5). Or an expansion valve (6) may be installed.

  A refrigerant (heat exchange fluid) is sealed in the refrigerant circuit (1). This refrigerant circulates in the refrigerant circuit (1), so that the underground heat exchanger (10) becomes an evaporator and the indoor heat exchanger (7) becomes a condenser to perform a vapor compression refrigeration cycle. It is configured.

  The underground heat exchanger (10) exchanges heat between the soil in the ground and the refrigerant flowing through the refrigerant circuit via carbon dioxide (heat medium) sealed inside. Details of the underground heat exchanger (10) will be described later.

  The compressor (5) is a hermetically sealed type, and has a variable capacity by an inverter (not shown) electrically connected to the compressor (5). The compressor (5) is configured to compress the sucked refrigerant to a predetermined pressure and discharge it.

  Although not shown, the indoor heat exchanger (7) is a cross fin type fin-and-and in which a plurality of heat transfer tubes are arranged in a plurality of paths and a number of aluminum fins are arranged orthogonal to the heat transfer tubes. It consists of a tube heat exchanger. An indoor fan (8) is installed in the vicinity of the indoor heat exchanger (7). Then, the refrigerant flows inside the heat transfer tube, the indoor air blown from the indoor fan (8) flows between the aluminum fins outside the heat transfer tube, and both perform heat exchange.

  The expansion valve (6) is an electronic expansion valve having a variable opening. The degree of decompression of the refrigerant flowing through the expansion valve (6) is adjusted by changing the opening degree of the expansion valve (6).

<Configuration of underground heat exchanger>
FIG. 2 is a longitudinal sectional view showing the configuration of the underground heat exchanger. As shown in FIG. 2, this underground heat exchanger (10) has an outer pipe (30) and an inner pipe (20), and the inner pipe (20) is inserted inside the outer pipe (30). This constitutes a double-pipe heat exchanger. The underground heat exchanger (10) is buried in the ground so that the tube axis direction of the outer tube (30) is along the vertical direction.

  The outer tube (30) has an upper closing plate (14) attached to its upper end and a lower closing plate (15) attached to its lower end to close the tube end. A sealed space (17) is formed inside the outer tube (30). In addition, a plurality of partition walls (16) are provided inside the tube at predetermined intervals in the tube axis direction. By these partition walls (16), the sealed space (17) is partitioned into a plurality of divided spaces (17a). A predetermined amount of carbon dioxide (heat medium) is sealed in each of the divided spaces (17a).

  In this way, by dividing the sealed space (17) into a plurality of divided spaces (17a), even if a crack occurs in the outer pipe (30) due to a natural disaster or the like, the divided space (17a The heat medium can be prevented from leaking into the ground from other divided spaces (17a) only by leaking the heat medium into the ground from). That is, the amount of carbon dioxide leaking from the outer pipe (30) to the outside can be reduced as compared with the case where the sealed space (17) is not partitioned. And since the amount of carbon dioxide leaking to the outside in the outer pipe (30) can be reduced, even if the heat medium leaks to the outside of the outer pipe (30), the underground heat exchanger (10) It is possible to minimize the decrease in the heat exchange capacity.

  Furthermore, even if the heat medium leaks from the cracked part into the ground, the ground does not contaminate the ground because the heat medium is carbon dioxide. Furthermore, even if the inner pipe (20) is damaged and the heat exchange fluid flowing inside it is leaked, it will be confined in the divided space (17a), and soil and groundwater will be trapped due to leakage into the ground. If the contamination can be avoided and the amount of leakage is small, the air conditioning operation can be continued. Therefore, the underground heat exchanger (10) in consideration of the global environment can be provided.

  The outer pipe (30) includes a metal pipe (31) made of metal and a reinforcing layer (32) that covers the outer peripheral surface of the metal pipe (31). The metal pipe (31) is composed of, for example, a high-pressure steel pipe. The thickness of the metal pipe (31) is set to be thin in order to reduce weight and cost.

  On the other hand, the reinforcing layer (32) is composed of a mortar (32b) in which a reinforcing wire (32a) is disposed. This reinforcing wire (32a) is composed of reinforcing bars etc. that extend along the tube axis direction, and cracks occur in the mortar (32b) even when tensile stress is applied to the reinforcing layer (32). It is for reinforcement so that there is no. Moreover, the mortar (32b) which has waterproofness and high heat conductivity is used for the reinforcement layer (32).

  Furthermore, a plurality of circumferential grooves (36) are formed along the circumferential direction on the inner peripheral surface (31a) of the metal pipe (31) of the outer pipe (30) (see FIG. 3).

  As described above, the outer pipe (30) is composed of the metal pipe (31) and the reinforcing layer (32), so that the thickness of the metal pipe (31) can be reduced by reducing the thickness. The strength of the pipe (30) as a whole can be sufficiently supplemented by the reinforcing layer (32). Therefore, even when carbon dioxide, which has a tendency to increase the internal pressure of the outer tube due to a high operating pressure range, is used as the heat medium, the outer tube (30) can have a tube structure that can withstand the internal pressure. .

  Furthermore, by covering the metal pipe (31) with a waterproof mortar (32b), it is possible to prevent rainwater or the like from being immersed in the ground and rusting the metal pipe (31). In addition, the metal pipe (31) can be insulated by the mortar (32b). For example, the metal pipe (31) can be prevented from being energized during a lightning strike, and the underground heat exchanger (10) itself or heat pump equipment This is advantageous in preventing damages and the like. In addition, by forming the reinforcing layer (32) using mortar (32b) with high thermal conductivity, the underground heat can be absorbed efficiently into the underground heat exchanger (10). Ability improves.

  The inner pipe (20) is a U-shaped pipe. The inner pipe (20) is inserted so that the two straight pipe portions penetrate the upper blocking plate (14) and the plurality of partition walls (16), and the pipe end portion protrudes from the sealed space (17). The inner pipe (20) is fixed to the outer pipe (30) so that the outer peripheral surface (20b) is in contact with the inner peripheral surface (31a) of the metal pipe (31) of the outer pipe (30). . A large number of circumferential grooves (26) of about 100 μm are formed on the outer peripheral surface (20b) of the inner tube (20) (see FIG. 3).

  Thus, by contacting the outer pipe (30) and the inner pipe (20), the carbon dioxide condensed and liquefied on the outer peripheral surface (20b) of the inner pipe (20) is reliably ensured. To the inner peripheral surface (31a) of the metal pipe (31).

  Moreover, the heat transfer performance of the inner pipe (20) can be improved by forming a large number of fine circumferential grooves (26) on the outer peripheral surface (20b) of the inner pipe (20). The heat exchange capacity of the heat exchanger (10) can be improved.

  One of the pipe end portions of the inner pipe (20) is connected to a refrigerant pipe (1a) extending from the discharge side of the compressor (5), and the other is a refrigerant pipe (1a) extending from the inlet side of the expansion valve (6). It is connected to the. By being connected in this way, a refrigerant passage (20a) through which the refrigerant of the refrigerant circuit (1) flows is formed inside the inner pipe (20).

-Driving action-
Next, the operation of the air conditioning system (A) according to this embodiment will be described. First, the high-pressure refrigerant discharged after being compressed to a predetermined pressure by the compressor (5) flows into the indoor heat exchanger (7). In the indoor heat exchanger (7), the high-pressure refrigerant releases heat to the indoor air sent from the indoor fan (8) and condenses, and then flows out of the indoor heat exchanger (7). On the other hand, the indoor air is warmed by this condensation heat. As a result, the room is heated.

  The high-pressure refrigerant that has flowed out of the indoor heat exchanger (7) flows into the expansion valve (6). In the expansion valve (6), the high-pressure refrigerant is depressurized to a predetermined pressure to become a low-pressure refrigerant, and then flows out from the expansion valve (6). At this time, the low-pressure refrigerant is decompressed by the expansion valve (6) so that the saturation temperature of the decompressed low-pressure refrigerant is lower than the temperature of the soil in the ground.

  The low-pressure refrigerant that has flowed out of the expansion valve (6) flows into the underground heat exchanger (10). In the underground heat exchanger (10), the low-pressure refrigerant absorbs the underground heat and evaporates, and then flows out of the underground heat exchanger (10). The low-pressure refrigerant that has flowed out of the underground heat exchanger (10) is sucked into the compressor (5), compressed to a predetermined pressure, and then flows into the indoor heat exchanger (7) again. As described above, the refrigerant circulates in the refrigerant circuit (1), thereby heating the room.

  Next, the operation of the underground heat exchanger (10) according to this embodiment will be described. The low-pressure refrigerant that has flowed out of the expansion valve (6) flows into the inner pipe (20) of the underground heat exchanger (10). When a low-pressure refrigerant having a temperature lower than the temperature of the soil in the ground flows into the inner pipe (20), the saturation temperature of carbon dioxide in each divided space (17a) is the temperature between the soil and the low-pressure refrigerant. Shall be.

  In this case, as shown in FIG. 4, the carbon dioxide enclosed in each divided space (17a) of the outer pipe (30) is the outer peripheral surface of the inner pipe (20) having a temperature lower than the saturation temperature of carbon dioxide ( Condensate in 20b). The refrigerant in the refrigerant circuit (1) absorbs the heat of condensation of carbon dioxide and evaporates. The evaporated refrigerant flows out of the underground heat exchanger (10) and is then sucked into the compressor (5).

  The carbon dioxide condensed and liquefied on the outer peripheral surface (20b) is held by the circumferential groove (26) on the outer peripheral surface (20b) of the inner pipe (20) without falling downward. It flows so as to spread in the circumferential direction along. And this liquefied carbon dioxide is guide | induced to the internal peripheral surface (31a) of the metal piping (31) of an outer pipe (30) through the contact part of an outer pipe (30) and an inner pipe (20). The carbon dioxide introduced to the inner peripheral surface (31a) of the metal pipe (31) of the outer pipe (30) is retained by the circumferential groove (36) of the outer pipe (30) without falling downward. It flows so as to expand in the circumferential direction along the groove (36). Carbon dioxide evaporates on the inner peripheral surface (31a).

  The carbon dioxide evaporated and gasified on the inner peripheral surface (31a) of the metal pipe (31) of the outer pipe (30) is caused by the difference in density of carbon dioxide in the divided space (17a). It moves toward the outer peripheral surface (20b) and condenses again on the outer peripheral surface (20b). Thus, by repeating the phase change of carbon dioxide, the ground soil outside the outer pipe (30) and the refrigerant flowing inside the inner pipe (20) exchange heat through the carbon dioxide. .

  As described above, according to the underground heat exchanger (10) according to the embodiment of the present invention, even if the thickness of the metal pipe (31) is reduced in order to reduce the weight of the outer pipe (30), The strength of the outer tube (30) as a whole can be sufficiently secured by the reinforcing layer (32). For this reason, the outer tube (30) should have a tube structure that can withstand the internal pressure even when carbon dioxide, whose internal pressure in the outer tube (30) increases due to the high operating pressure range, is used as the heat medium. Can do.

  In addition, since insulation can be improved by covering the metal pipe (31) with mortar (32b), it is possible to prevent the metal pipe (31) from being energized when a lightning strike occurs, and the underground heat exchanger (10) It is possible to prevent damage to itself and the heat pump equipment. Furthermore, since the outer diameter of the outer tube (30) is increased by covering with the mortar (32b), the heat transfer area can be increased and the heat exchange capacity is improved.

  Further, if the metal pipe (31) is covered with a waterproof mortar (32b), it is possible to prevent rainwater or the like from entering the ground and rusting the metal pipe (31). If the metal pipe (31) is covered with mortar (32b) with high thermal conductivity, the underground heat can be absorbed efficiently into the underground heat exchanger (10). Exchange ability is improved.

<Modification 1>
FIG. 5 is a longitudinal sectional view showing the configuration of the underground heat exchanger according to the first modification of the present embodiment. As shown in FIG. 5, the reinforcing layer (32) of the outer pipe (30) of the underground heat exchanger (10) is provided with a flange portion (33).

  Specifically, the flange part (33) is formed of a ring-shaped disk member that protrudes radially outward from the outer peripheral surface of the metal pipe (31) of the outer pipe (30). A plurality (three in FIG. 5) of flange portions (33) are arranged at predetermined intervals in the tube axis direction of the outer tube (30). Then, the mortar (32b) is filled in the gap between the flange portions (33), thereby reinforcing the metal pipe (31) with the reinforcing wire (32a), the mortar (32b), and the flange portion (33). Layer (32) is constructed.

  Thus, by providing the flange portion (33) in the reinforcing layer (32), the strength of the outer tube (30) as a whole can be further increased. Therefore, even if the thickness of the mortar (32b) constituting the reinforcing layer (32) is reduced, the strength of the outer tube (30) can be sufficiently secured, which is advantageous for further weight reduction.

<Modification 2>
FIG. 6 is a longitudinal sectional view showing the configuration of the underground heat exchanger according to the second modification of the present embodiment. As shown in FIG. 6, a linear member (34) is provided on the reinforcing layer (32) of the outer pipe (30) of the underground heat exchanger (10).

  Specifically, the said linear member (34) is comprised with the reinforcing bar wound in the circumferential direction along the outer peripheral surface of the metal piping (31) of an outer tube | pipe (30). And the reinforcement layer (32) is comprised by covering metal piping (31) with the mortar (32b) with the linear member (34).

  Thus, the strength of the entire outer pipe (30) can be further increased by winding the linear member (34) around the metal pipe (31). Therefore, even if the thickness of the mortar (32b) constituting the reinforcing layer (32) is reduced, the strength of the outer tube (30) can be sufficiently secured, which is advantageous for further weight reduction.

<Other embodiments>
About the said embodiment, it is good also as following structures. For example, in the present embodiment, the air conditioning system (A) is configured by a heating device, but is not limited thereto, and the air conditioning system (A) may be configured by a cooling device. In this case, the underground heat exchanger (10) forms a condenser, the indoor heat exchanger (7) forms an evaporator, and the underground heat exchanger (10) is higher than the soil in the ground. Temperature refrigerant flows in. Thereby, the outer peripheral surface (20b) of the inner pipe (20) forms an evaporation surface, and the inner peripheral surface (31a) of the metal pipe (31) of the outer tube (30) forms a condensing surface.

  In the present embodiment, carbon dioxide as a heat medium is sealed in the sealed space (17) of the outer pipe (30), and heat exchange is performed with the refrigerant in the inner pipe (20) through the carbon dioxide. The so-called interstitial underground heat exchanger (10) has been described. For example, only the inner pipe (20) covered with the reinforcing layer (32) is buried in the ground, and the inner pipe (20) is covered. It may be a so-called direct expansion type underground heat exchanger (10) in which carbon dioxide as a heat exchange fluid is circulated to directly exchange heat.

  As described above, the present invention can provide a highly practical effect that can provide a ground heat exchanger that is reduced in cost and weight while sufficiently securing the strength of the outer tube. It is useful and has high industrial applicability.

It is a refrigerant circuit figure of the air-conditioning system using the underground heat exchanger concerning the embodiment of the present invention. It is a longitudinal section showing the composition of an underground heat exchanger. It is a detailed view of the inside of the underground heat exchanger. It is an enlarged view in operation | movement of an underground heat exchanger. It is a longitudinal cross-sectional view which shows the structure of the underground heat exchanger which concerns on the modification 1 of this embodiment. It is a longitudinal cross-sectional view which shows the structure of the underground heat exchanger which concerns on the modification 2 of this embodiment.

Explanation of symbols

A Air conditioning system
1 Refrigerant circuit
5 Compressor
6 Expansion mechanism
7 Use side heat exchanger
10 Heat source side heat exchanger (Ground heat exchanger)
20 Inner pipe
30 outer pipe
31 Metal piping
32 Reinforcing layer
32a Reinforcing wire
32b mortar
33 Flange
34 Linear members

Claims (4)

An outer pipe (30) embedded in the ground so that the pipe axis direction is along the vertical direction, and an inner pipe (20) inserted inside the outer pipe (30) and through which the heat exchange fluid flows. An underground heat exchanger with
The outer pipe (30) includes a metal metal pipe (31) in which a pipe end is closed and a heat medium is enclosed therein, and a mortar (32b) in which a reinforcing wire (32a) is provided. And a reinforcing layer (32) covering the outer peripheral surface of the metal pipe (31). In claim 1,
The reinforcing layer (32) includes a plurality of flange portions (33) projecting radially outward from the outer peripheral surface of the metal pipe (31) and arranged at predetermined intervals in the tube axis direction. An underground heat exchanger characterized by In claim 1 or 2,
The said reinforcement layer (32) is equipped with the linear member (34) wound in the circumferential direction along the outer peripheral surface of the said metal piping (31), The underground heat exchanger characterized by the above-mentioned. The compressor (5), the heat source side heat exchanger (10), the expansion mechanism (6), and the use side heat exchanger (7) are connected to provide a refrigerant circuit (1) that performs a vapor compression refrigeration cycle. An air conditioning system,
By connecting the inner pipe (20) of the underground heat exchanger (10) according to any one of claims 1 to 3 to the refrigerant circuit (1), the underground heat exchanger ( An air conditioning system characterized in that the heat source side heat exchanger (10) is constituted by 10).

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