JP5381325B2 - Heat exchanger and air conditioning system - Google Patents

Description

  The present invention relates to a heat exchanger installed in the ground or underwater, and an air conditioning system using the heat exchanger.

  Some so-called heat pump heating systems that perform heating by a refrigeration cycle use a geothermal heat or heat in water as a heat source to evaporate the refrigerant. For example, a geothermal heat exchanger that collects geothermal heat from the ground is used in a heat pump heating system that uses geothermal heat (see, for example, Patent Document 1). In the underground heat exchanger of Patent Document 1, a pipe (referred to as an embedded pipe in this specification) having a heat medium (secondary medium) therein is embedded in the ground, and the heat medium in the embedded pipe is generated by geothermal heat. Evaporate. Then, the pipe is branched from the buried pipe, a heat exchanger is attached to the branch pipe, and the heat recovered by the heat exchanger is used as a heat source of the heat pump heating system.

International Publication No. WO2004 / 111559 Pamphlet

  However, for example, in the case of underground heat exchangers that collect heat from soil, the heat transfer resistance of the soil is large, so that the heat exchange performance of conventional underground heat exchangers is small, for example, a short length or a tube When using a small diameter, it was difficult to obtain a sufficient amount of heat. Therefore, for example, in order to obtain a sufficient amount of heat with a so-called vertical underground heat exchanger in which the underground heat exchanger is embedded in the vertical direction, it is necessary to embed the underground heat exchanger to a considerable depth. In addition, since the heat recovered indirectly using the phase change of the heat medium filled in the buried pipe is used as a heat source of the heat pump heating system, the recovery of the ground heat and its utilization rate are inevitably reduced. Furthermore, if a system that recovers geothermal heat by circulating antifreeze such as water, ethylene glycol, or alcohol aqueous solution to the underground heat exchanger, it will be buried about 100m in the underground heat exchanger in a general household heating system. Some examples require depth. Thus, when the burial depth of the underground heat exchanger is required, its installation cost becomes a problem. For pipes buried at such a depth, a pump is required to transport the heat medium (secondary medium) in the pipe, and the power consumption of the pump reduces the efficiency of the entire heating system. Can cause problems. These problems can also occur when a conventional underground heat exchanger is used as a cooling condenser.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a heat exchanger that can contribute to a reduction in power consumption of an air conditioning system in an area where the outside air temperature is low such as a cold district.

In order to solve the above problems, the first invention is
A heat exchanger installed in the ground or in water,
An outer pipe (51) installed in the ground or in water, into which refrigerant in the refrigeration cycle is introduced ;
A heating liquid pipe (52) for introducing the refrigerant into the outer pipe (51) during heating operation in which the outer pipe (51) serves as an evaporator;
Spray means (53) for spraying the refrigerant introduced into the heating liquid pipe (52) onto the inner wall of the outer pipe (51);
During cooling operation in which the outer pipe (51) serves as a condenser, a cooling liquid pipe (56) for deriving the refrigerant condensed in the outer pipe (51) is provided.
The cooling liquid pipe (56) extends to the lower end of the outer pipe (51) .

Thereby, in the heat exchanger installed in the ground or underwater, the refrigerant (working fluid) in the refrigeration cycle performs heat exchange by a direct expansion method in which heat is directly obtained from the ground or underwater and evaporated .

This also, during the heating operation, the refrigerant is sprayed to the inner surface wall of the outer tube (51). Then, the sprayed refrigerant is turned into a liquid film on the inner wall and evaporates.

  Thereby, at the time of heating operation, the refrigerant is sprayed uniformly on the entire inner wall of the outer pipe (51). Then, the sprayed refrigerant is turned into a liquid film on the inner wall and evaporates. Further, during the cooling operation, the refrigerant condenses on the inner wall of the outer pipe (51).

  Thereby, during cooling operation, the refrigerant is separated into two phases in the outer pipe (51), and the liquid refrigerant at the bottom of the outer pipe (51) is derived by the pressure of the gas refrigerant.

In addition, the second invention,
In the heat exchanger of the first invention,
The spray means (53) is a plurality of spray holes (53) provided in the heating liquid pipe (52).

  Thereby, a refrigerant | coolant is sprayed on an inner surface wall from the spray hole (53), and a refrigerant | coolant turns into a liquid film by this inner surface wall.

In addition, the third invention,
In the heat exchanger of the first invention,
The spray means (53) is a plurality of nozzles (80) provided in the heating liquid pipe (52).

  Thereby, a refrigerant | coolant is sprayed on an inner surface wall from a nozzle (80), and a refrigerant | coolant turns into a liquid film by this inner surface wall.

In addition, the fourth invention is
In the heat exchanger of the first invention,
The heating liquid pipe (52) is provided at the center of the outer pipe (51).

As a result, the distance between the inner wall of the outer pipe (51) and the outer wall of the heating liquid pipe (52) is kept constant .

In addition, a fifth aspect of the present invention,
In the heat exchanger of the first invention,
A wick (81) is provided in the outer pipe (51) along the inner wall of the outer pipe (51).

  Thereby, the wick (81) permeates and holds the sprayed liquid refrigerant and brings the held liquid refrigerant into contact with the inner wall of the outer pipe (51).

In addition, the sixth invention,
In the heat exchanger of the first invention,
A groove (82) for holding a refrigerant is formed on the inner wall of the outer pipe (51).

Thus, the groove (82) holds the sprayed liquid refrigerant and forms a liquid film on the inner wall of the outer pipe (51) .

In addition, a seventh aspect of the present invention,
In the heat exchanger of the first invention,
The outer pipe (51) includes a compressor pipe (55) for leading the refrigerant in the outer pipe (51) to the compressor (30),
The compressor pipe (55) is formed with an oil return mechanism (90) for returning the lubricating oil accumulated at the bottom of the outer pipe (51) to the compressor (30).

  Thereby, when lubricating oil (refrigerating machine oil) accumulates at the bottom of the outer pipe (51) during heating operation, the lubricating oil is returned to the compressor (30) by the oil return mechanism (90).

Further, the eighth invention is
An air conditioning system comprising the heat exchanger according to the first invention and performing a refrigeration cycle.

  Thereby, air conditioning is performed using the heat exchanger which performs heat exchange in the ground or underwater by a direct expansion method.

In addition, the ninth invention,
The heat exchanger of the first invention;
A switching valve (60) for switching so that the refrigerant is selectively introduced into either the heating liquid pipe (52) or the cooling liquid pipe (56);
An air conditioning system comprising a refrigerant circuit (10) for performing a refrigeration cycle.

  Thereby, either a cooling or heating (air conditioning) is selectively performed using a heat exchanger that performs heat exchange in the ground or underwater by a direct expansion method.

  According to the first invention, a pump for transporting the secondary medium becomes unnecessary, which can contribute to reduction of power consumption of the air conditioning system.

Further, according to the first , second and third inventions, the refrigerant is formed into a liquid film on the inner wall of the outer pipe (51) and directly evaporated by geothermal heat or heat in water. Will improve.

According to the fourth invention, the distance between the inner wall of the outer pipe (51) and the outer wall of the heating liquid pipe (52) is kept constant, so that the refrigerant is evenly distributed in the outer pipe (51). The heat exchange performance is further improved by being sprayed on the inner wall of the glass.

According to the first invention, the refrigerant is separated into two phases in the outer pipe (51), and the liquid refrigerant at the bottom of the outer pipe (51) is derived by the pressure of the gas refrigerant. The refrigerant can be transported efficiently. As a result, the heat exchange performance is improved.

According to the fifth aspect of the invention, the sprayed refrigerant is held on the inner wall of the outer pipe (51) by the wick (81), so that uniform wetting is ensured with respect to the inner wall of the outer pipe (51). The heat exchange performance can be improved particularly during heating operation by efficiently receiving and vaporizing from the wall surface.

According to the sixth aspect of the invention, since the sprayed refrigerant is held on the inner wall of the outer pipe (51) by the groove (82), uniform wetting is ensured with respect to the inner wall of the outer pipe (51). The heat exchange performance can be improved particularly during heating operation by efficiently receiving and vaporizing from the wall surface.

Further, according to the first invention, during the heating operation, since the liquid film is evaporated on the inner wall of the outer pipe (51), the heat exchange performance of the heat exchanger is improved. Further, since the refrigerant can be efficiently conveyed during the cooling operation, the heat exchange performance is also improved.

Further, according to the seventh aspect , since the lubricating oil accumulated at the bottom of the outer pipe (51) during the heating operation is returned to the compressor (30), the compressor (30) can be stably operated. Become.

According to the eighth aspect of the present invention, in the air conditioning system using the heat exchanger installed in the ground or in water, the power consumption of the system can be reduced.

According to the ninth aspect , in the air conditioning system capable of switching between cooling and heating using a heat exchanger installed in the ground or underwater, it is possible to reduce the power consumption of the air conditioning system. In addition, the heat exchange performance is improved.

It is a system diagram of an air-conditioning system including an underground heat exchanger (50) according to an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the structure of a underground heat exchanger (50). It is a figure which shows typically the state which installed the underground heat exchanger (50) in the ground. It is a figure explaining the state in the underground heat exchanger (50) at the time of heating operation. It is a figure explaining the state in the underground heat exchanger (50) at the time of air_conditionaing | cooling operation. It is a system diagram of an air-conditioning system (1) that includes the underground heat exchanger (50) according to the embodiment of the present invention and performs only heating. It is a figure which shows typically the state which installed the underground heat exchanger (50) inclining. It is a longitudinal cross-sectional view which shows the underground heat exchanger (50) which provided the ejector (90) as an oil return mechanism. It is a longitudinal cross-sectional view explaining the structure of an ejector (90). It is a figure which shows typically the state which has arrange | positioned the underground heat exchanger (50) diagonally. It is a figure which shows the underground heat exchanger (50) which comprised the oil return mechanism with the piping for compressors (55). It is a figure which shows typically the state which has arrange | positioned the underground heat exchanger (50) diagonally. It is a figure which shows typically the state which installed the underground heat exchanger (50) horizontally. It is a figure which shows typically the state which installed the underground heat exchanger (50) horizontally. It is a figure which shows typically the state which installed the heat exchanger (50) in water. It is a figure which shows the other structural example of a spraying means. It is a figure which shows the other structural example of an outer pipe | tube (51), (A) is the cross section of an outer pipe | tube (51), (B) is the perspective view which cut off a part of outer pipe | tube (51). It is a cross-sectional view showing still another configuration example of the outer tube (51).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use. In the following description of each embodiment and modification, components having the same functions as those described once will be given the same reference numerals and description thereof will be omitted.

Embodiment 1 of the Invention
Embodiment 1 demonstrates the example of the heat exchanger (ground heat exchanger) installed in the ground as an example of the heat exchanger of this invention. The underground heat exchanger according to the embodiment of the present invention is used, for example, in a heat pump type air conditioning system capable of cooling and heating operation. During heating operation, the underground heat exchanger functions as a vaporizer and uses the soil as a heat source to generate geothermal heat for heating. It collects heat and functions as a condenser during cooling operation to dissipate heat to the soil. In addition, the soil here includes not only what is formed only of earth and sand but also a so-called aquifer including both earth and sand and water and a bedrock where rocks are continuously distributed. That is, this underground heat exchanger may perform heat exchange not only on earth and sand but also on underground water, bedrock, or all of them depending on the installation location and depth.

<Overall configuration of air conditioning system>
FIG. 1 is a system diagram of an air conditioning system (1) including a ground heat exchanger (50) according to an embodiment of the present invention. The air conditioning system (1) of this embodiment is provided with the refrigerant circuit (10), as shown in FIG. The refrigerant circuit (10) includes a four-way switching valve (20), a compressor (30), an indoor heat exchanger (40), a ground heat exchanger (50), a switching valve (60), and an expansion valve (70 ) Is connected. The refrigerant circuit (10) is filled with carbon dioxide as a refrigerant.

  The four-way switching valve (20) is provided with four ports from first to fourth ports. The four-way switching valve (20) includes a first state (state indicated by a broken line in FIG. 1) in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other. Can be switched to a second state (state indicated by a solid line in FIG. 1) in which the second port and the third port communicate with each other. In FIG. 1, the solid line indicates the state of the four-way switching valve (20) during the heating operation and the broken line indicates the cooling operation.

  The compressor (30) sucks and compresses the refrigerant from the suction port, and discharges the compressed refrigerant from the discharge port. Specifically, various compressors such as a scroll compressor can be adopted as the compressor (30). In the refrigerant circuit (10), the compressor (30) has a suction port connected to the second port of the four-way switching valve (20) and a discharge port connected to the first port of the four-way switching valve (20). .

  The indoor heat exchanger (40) is an air heat exchanger for exchanging heat between the refrigerant and room air. In this air conditioning system (1), the indoor heat exchanger (40) is incorporated in a so-called indoor unit arranged in a room that performs air conditioning. The heat of the high-pressure refrigerant sent from the compressor (30) is radiated to the room air during the heating operation, and the heat of the room air is absorbed by the low-pressure refrigerant sent from the expansion valve (70) during the cooling operation. In this refrigerant circuit (10), one end of the indoor heat exchanger (40) is connected to the expansion valve (70), and the other end is connected to the fourth port of the four-way switching valve (20). Then, the radiated refrigerant is caused to flow out to the expansion valve (70) during the heating operation, and the refrigerant flowing from the expansion valve (70) is made to absorb heat during the cooling operation. For this indoor heat exchanger (40), for example, a cross fin type fin-and-tube heat exchanger or the like can be employed. An indoor fan (41) is installed in the vicinity of the indoor heat exchanger (40). The indoor fan (41) blows conditioned air into the room.

  The underground heat exchanger (50) exchanges heat with the soil. Specifically, this underground heat exchanger (50) collects heat for heating using geothermal heat as a heat source during heating operation, and functions as a condenser during cooling operation to dissipate heat to the soil (in FIG. 1, (The shaded arrows with the arrows indicating the heat flow of the underground heat exchanger (50) are for heating, and the white arrows are for cooling operation). As shown in FIG. 2, the underground heat exchanger (50) of this embodiment includes an outer pipe (51), a heating liquid pipe (52), a compressor pipe (55), and a cooling liquid pipe. (56).

  The outer pipe (51) is formed in a tubular shape whose both ends are closed, and in this example, it is buried vertically in the ground. For example, FIG. 3 is a diagram schematically showing a state in which the underground heat exchanger (50) is installed in the ground. The stratum includes a layer mainly composed of earth and sand, a layer including earth and sand, a layer mainly including water, and a bedrock in which rocks are continuously distributed. This underground heat exchanger (50) may be installed in any formation. FIG. 3 shows a state in which the underground heat exchanger (50) is installed in each of these layers. For example, the underground heat exchanger (50) performs heat exchange only in one of the formations. May be installed to do.

  The heating liquid pipe (52) is formed in a tubular shape with a closed tip, and a gas-liquid two-phase refrigerant is introduced during the heating operation to spray the refrigerant on the inner wall of the outer pipe (51). Specifically, the heating liquid pipe (52) is inserted into the outer pipe (51) from the upper side of the outer pipe (51) (the side on the ground surface with the outer pipe (51) embedded). When inserted, the distal end side (closed side) extends to the vicinity of the bottom surface of the outer tube (51). The wall surface of the heating liquid pipe (52) is provided with means (spraying means) for spraying the refrigerant introduced into the heating liquid pipe (52) onto the inner wall of the outer pipe (51). ing. Specifically, the spray means of this embodiment is a plurality of spray holes (53). These spray holes (53) are provided over the entire length of the heating liquid pipe (52). Ideally, the number and interval of the spray holes (53) should be determined so that the sprayed refrigerant is uniformly applied in the circumferential direction and the length direction of the inner wall of the outer pipe (51). In the outer pipe (51), spacers (54) are provided at a plurality of locations, and the heating liquid pipe (52) is held substantially at the center of the outer pipe (51). The spacer (54) is made of a material having a low heat transfer coefficient. Moreover, it is a shape which does not restrain the flow of steam. In this way, the distance between the inner wall of the outer pipe (51) and the outer wall of the heating liquid pipe (52) by holding the heating liquid pipe (52) substantially at the center of the outer pipe (51). Is kept constant, and the refrigerant in the heating liquid pipe (52) can be sprayed evenly on the inner wall of the outer pipe (51).

  The compressor pipe (55) is a pipe connecting the outer pipe (51) and the compressor (30). One end of the compressor pipe (55) is opened in the outer pipe (51) near the upper end of the outer pipe (51), and the other end is connected to the third port of the four-way switching valve (20). Yes. That is, in this air conditioning system (1), the compressor pipe (55) introduces the gas refrigerant in the outer pipe (51) into the compressor (30) via the four-way switching valve (20) during heating operation. During the cooling operation, the high-pressure gas refrigerant discharged from the compressor (30) is introduced into the outer pipe (51).

  The cooling liquid pipe (56) is formed in a tubular shape, and at the time of cooling operation, the liquid refrigerant accumulated at the bottom of the outer pipe (51) is led to the expansion valve (70) via the switching valve (60). . Specifically, the cooling liquid pipe (56) is inserted into the outer pipe (51) from the upper side of the outer pipe (51), and the end thereof is near the bottom of the outer pipe (51). It extends and opens near the bottom.

  As described above, in the outer pipe (51), during the heating operation, the refrigerant (two-phase refrigerant) is sprayed on the inner wall of the outer pipe (51) by the heating liquid pipe (52). The refrigerant evaporated in (51) (that is, the gas refrigerant) is led out from the compressor pipe (55) above the outer pipe (51). Further, during the cooling operation, the gas refrigerant is introduced from the compressor pipe (55), condensed on the inner wall surface of the outer pipe (51), and collected in the bottom of the outer pipe (51). Derived from (56). That is, the underground heat exchanger (50) is a heat exchanger that exchanges heat with soil by a direct expansion method.

  The switching valve (60) selectively connects the expansion valve (70) to one of the heating liquid pipe (52) and the cooling liquid pipe (56) of the underground heat exchanger (50). Specifically, the expansion valve (70) and the heating liquid pipe (52) are connected during heating operation, and the expansion valve (70) and the cooling liquid pipe (56) are connected during cooling operation. . That is, the switching valve (60) switches so that the refrigerant is selectively introduced into either the heating liquid pipe (52) or the cooling liquid pipe (56).

  As described above, one end of the expansion valve (70) is connected to the switching valve (60), and the other end is connected to the indoor heat exchanger (40). During heating operation, the refrigerant flowing in from the indoor heat exchanger (40) is expanded and depressurized to a predetermined pressure, and then flows out to the heating liquid pipe (52) via the switching valve (60). . Further, during the cooling operation, the refrigerant flowing in is reduced to a predetermined pressure from the outer pipe (51) through the cooling liquid pipe (56) and the like, and flows out to the indoor heat exchanger (40).

-Driving action-
Next, the operation in the air conditioning system (1) will be described.

(Heating operation)
First, the heating operation will be described. During the heating operation, the four-way selector valve (20) is switched to the second state. Thereby, in the four-way selector valve (20), the first port communicates with the fourth port, and the second port communicates with the third port. The switching valve (60) is switched so that the expansion valve (70) communicates with the heating liquid pipe (52).

  In this state, when the compressor (30) is put into an operating state, the compressed refrigerant (gas refrigerant) is discharged from the discharge port of the compressor (30). Then, the refrigerant discharged from the compressor (30) is sent to the indoor heat exchanger (40). The refrigerant that has flowed into the indoor heat exchanger (40) radiates heat to the indoor air in the indoor heat exchanger (40). In the indoor heat exchanger (40), the indoor air is heated, and the heated indoor air is sent back into the room by the indoor fan (41). The refrigerant radiated by the indoor heat exchanger (40) is sent to the expansion valve (70). The refrigerant flowing into the expansion valve (70) is depressurized when passing through the expansion valve (70), and then introduced into the heating liquid pipe (52) via the switching valve (60). The refrigerant introduced into the heating liquid pipe (52) is in a gas-liquid two-phase state, and in the outer pipe (51), from the spray hole (53) provided in the heating liquid pipe (52). And sprayed on the inner wall of the outer tube (51). As a result, as shown in FIG. 4, the liquid refrigerant adheres to the inner wall of the outer tube (51) to form a liquid film.

  The suction amount of the compressor is controlled, the pressure inside the outer pipe (51) is manipulated, and a temperature difference is provided so that the vaporization temperature and the evaporation amount of the refrigerant are kept constant. The evaporation temperature is set from the thermal resistance of the soil and the load power of the compressor. The refrigerant formed into a liquid film on the inner wall of the outer tube (51) absorbs heat from the inner wall and evaporates. As a result, the pressure in the outer pipe (51) increases and the suction pressure of the compressor (30) acts in the outer pipe (51), so the gas refrigerant in the outer pipe (51) Derived from the compressor pipe (55) and introduced into the suction port of the compressor (30) through the four-way switching valve (20). The compressor (30) sucks and compresses the refrigerant, and discharges it to the indoor heat exchanger (40) through the four-way switching valve (20).

  In the air conditioning system (1), the above operation is repeated, and a refrigeration cycle (heating in this example) is performed in which the refrigerant is compressed by the compressor (30) using the underground heat exchanger (50) as an evaporator. In the heating operation, the cooling liquid pipe (56) is not used.

  As described above, in this air conditioning system (1), during the heating operation, the refrigerant is sprayed on the inner wall of the outer pipe (51) by the heating liquid pipe (52), and the liquid is sprayed on the inner wall of the outer pipe (51). Since the film is formed, the liquid refrigerant can be efficiently brought into contact with the inner wall of the outer pipe (51) and evaporated. Therefore, the heat exchange performance of the underground heat exchanger (50) is improved.

(Cooling operation)
Next, the cooling operation will be described. During the cooling operation, first, the four-way switching valve (20) is switched to the first state. Thereby, in the four-way selector valve (20), the first port and the third port are communicated, and the second port and the fourth port are communicated. The switching valve (60) is switched so that the expansion valve (70) and the cooling liquid pipe (56) communicate with each other.

  In this state, when the compressor (30) is put into an operating state, the compressed refrigerant (gas refrigerant) is discharged from the discharge port of the compressor (30). Then, the refrigerant discharged from the compressor (30) is sent into the outer pipe (51) of the underground heat exchanger (50) through the four-way switching valve (20) and the compressor pipe (55). It is done.

  The temperature of the gas refrigerant introduced into the outer pipe (51) is operated so as to be higher than the temperature of the soil, and the heat is radiated and condensed on the inner wall of the outer pipe (51). The condensed refrigerant flows downward along the inner wall of the outer pipe (51) and accumulates at the bottom of the outer pipe (51) as shown in FIG. 5, and eventually opens the cooling liquid pipe (56). Reach the end. At this time, the pressure in the outer pipe (51) increases due to the introduction of the gas refrigerant. Moreover, the indoor heat exchanger (40) side has a lower pressure than the internal pressure of the outer pipe (51). Thereby, the liquid refrigerant accumulated in the outer pipe (51) is pushed up in the cooling liquid pipe (56). The liquid refrigerant pushed up in the liquid pipe for cooling (56) is introduced into the expansion valve (70) through the switching valve (60) and is decompressed by the expansion valve (70), and then the indoor heat exchanger (40 ). The refrigerant flowing into the indoor heat exchanger (40) absorbs heat from the indoor air and evaporates. As a result, the indoor air is cooled in the indoor heat exchanger (40), and the cooled indoor air is sent back into the room by the indoor fan (41). The refrigerant evaporated in the indoor heat exchanger (40) is introduced into the suction port of the compressor (30). The compressor (30) sucks and compresses the refrigerant, and discharges it to the outer pipe (51) via the compressor pipe (55).

  In the air conditioning system (1), the above operation is repeated, and a refrigeration cycle (cooling in this example) is performed in which the refrigerant is compressed by the compressor (30) using the underground heat exchanger (50) as a condenser. Note that the liquid pipe for heating (52) is not used during the cooling operation.

  In addition, since a refrigerant | coolant evaporates in an outer pipe | tube (51) at the time of heating operation, it is possible that lubricating oil (refrigeration machine oil) accumulates in the bottom part of this outer pipe | tube (51). In such a case, for example, in the air conditioning system (1), if the cooling operation is temporarily performed while the heating operation is stopped or during the heating operation, the lubricating oil can be returned to the compressor (30). . That is, during cooling operation, the refrigerant condenses in the underground heat exchanger (50) and accumulates at the bottom of the outer pipe (51), so that the lubricating oil is dissolved in the condensed refrigerant, and the molten lubricating oil Will return to the compressor (30) together with the refrigerant. Further, the lubricating oil may be separated at a stage before introducing the refrigerant into the underground heat exchanger (50).

<< Effect in this embodiment >>
As described above, in this air conditioning system (1), the refrigerant is separated into two phases in the outer pipe (51), and the liquid refrigerant is derived by the pressure of the gas refrigerant. Therefore, the liquid refrigerant in the outer pipe (51) can be efficiently conveyed, and the heat exchange performance is improved.

  As described above, since the present embodiment is a direct expansion method, unlike the conventional underground heat exchanger, a pump for transporting the secondary medium is not required, and the power consumption of the system can be reduced. .

  In the present embodiment, the heat exchange performance is improved both during the cooling operation and during the heating operation. Therefore, it is possible to reduce the size of the underground heat exchanger. This miniaturization can be expected to reduce the cost of the air conditioning system.

<< Embodiment 2 of the Invention >>
The above-mentioned underground heat exchanger (50) can also be used for an air conditioning system that performs only a cooling operation or an air conditioning system that performs only a heating operation.

  FIG. 6 is a system diagram of an air conditioning system that performs only heating. As shown in FIG. 6, the switching valve (60) and the four-way switching valve (20) are unnecessary in the air conditioning system that performs only heating. That is, in the air conditioning system that performs only heating, the four-way switching valve (20) is set to the second state and the switching valve (60) is switched to the heating liquid pipe (52) side in the air conditioning system of the first embodiment. It is an equivalent refrigerant circuit. Therefore, in the underground heat exchanger (50) of the air conditioning system that performs only heating, the cooling liquid pipe (56) is unnecessary.

  Similarly, even in an air conditioning system that only performs cooling, the switching valve (60) and the four-way switching valve (20) are unnecessary, and the four-way switching valve (20) is set to the first state in the air conditioning system of Embodiment 1, and A refrigerant circuit equivalent to the case where the switching valve (60) is switched to the cooling liquid pipe (56) side is formed. The underground heat exchanger (50) of the air conditioning system that only performs cooling does not require the heating liquid pipe (52). In order to return the lubricating oil accumulated in the underground heat exchanger (50) to the compressor (30), for example, the same configuration as that of the first embodiment can be applied.

<< Modification of Embodiments 1 and 2 >>
In addition, the underground heat exchanger (50) of Embodiment 1 and 2 can also be installed in inclination other than the vertical direction. Drawing 7 is a figure showing typically the state where the underground heat exchanger (50) was installed inclining. Even if it installs in this way, heat exchange is performed like said each embodiment. In the figure, “HP” indicates a main body portion (a portion other than the heat exchanger) of the air conditioning system (1) (or the air conditioning system of the second embodiment) (the same applies hereinafter). .

<< Embodiment 3 of the Invention >>
In the third embodiment, the underground including a mechanism (hereinafter also referred to as an oil return mechanism) that returns the lubricating oil accumulated in the underground heat exchanger (50) to the compressor (30) during heating operation or the like. An example of a heat exchanger will be described. FIG. 8 is a longitudinal sectional view schematically showing an underground heat exchanger provided with an oil return mechanism. Specifically, the underground heat exchanger of FIG. 8 is obtained by providing an ejector (90) as an oil return mechanism to the underground heat exchanger (50) of the first embodiment. FIG. 9 is a longitudinal sectional view for explaining the structure of the ejector (90). As shown in FIG. 9, the ejector (90) includes an ejector body (91), an oil return pipe (92), and a filter (93).

  As shown in FIG. 9, the ejector body (91) has a tapered flow path (91a) and a straight flow path (91b) formed continuously inside, and above the underground heat exchanger (50). Thus, the portion of the straight channel (91b) is connected to the compressor pipe (55). The tapered channel (91a) opens to the bottom surface side of the outer tube (51).

  The oil return pipe (92) is a tubular member, and one end of the oil return pipe (92) opens in the straight flow path (91b) of the ejector body (91). In addition, a filter (93) for removing dust in the lubricating oil is attached to the other end of the oil return pipe (92), and the filter (93) collects the lubricating oil collected at the bottom of the outer pipe (51). The oil return pipe (92) extends to the bottom of the outer pipe (51) so as to be immersed in the water.

  In the present embodiment, when the underground heat exchanger (50) is disposed obliquely, as shown in FIG. 10, the lubricating oil suction portion (that is, the filter (93) is disposed at the lowermost portion of the liquid layer. )) Is preferably located.

<< Oil return by oil return mechanism (ejector (90)) >>
During the heating operation, as described in the first embodiment, the pressure in the outer pipe (51) rises, and the suction pressure of the compressor (30) acts in the outer pipe (51). The gas refrigerant in the outer pipe (51) is introduced from the tapered flow path (91a) of the ejector body (91), and further passes through the straight flow path (91b) portion, and from the compressor pipe (55). Derived. At this time, the refrigerant increases in speed when passing from the tapered channel (91a) to the straight channel (91b), and the opening on the straight channel (91b) side of the oil return pipe (92) is depressurized. It becomes a state. As a result, the lubricating oil accumulated at the bottom of the outer pipe (51) is drawn into the oil return pipe (92) through the filter (93) and ejected from the opening on the straight flow path (91b) side. The jetted lubricating oil returns to the compressor (30) together with the gaseous refrigerant in the straight flow path (91b). Thus, by returning the lubricating oil to the compressor (30), the compressor (30) can be stably operated.

  Depending on the type of refrigerant and lubricating oil used, the refrigerant may accumulate on the bottom side of the lubricating oil. In that case, the lubricating oil will be removed from the underground heat exchanger (50) together with the refrigerant. Will be carried to.

<< Embodiment 4 of the Invention >>
In the fourth embodiment, another example of the oil return mechanism will be described. FIG. 11 is a view showing an underground heat exchanger (50) in which the oil return mechanism is configured by a compressor pipe (55). In FIG. 11, (A) is a longitudinal sectional view showing the entire structure of the underground heat exchanger (50), and (B) is a diagram for explaining the configuration of the compressor pipe (55). As shown in FIGS. 11A and 11B, the compressor pipe (55) of this example is formed of a U-shaped tube, and the curved portion of the U-shaped tube is the bottom of the outer tube (51). So that it can be immersed in a pool of lubricating oil.

  The compressor pipe (55) is provided with an upper hole (55a) that opens upward in the outer pipe (51). Furthermore, a lower hole (55b) is provided in a curved portion of the U-shaped tube (specifically, a portion immersed in a lubricating oil reservoir). Further, a filter (55c) for removing dust in the lubricating oil is attached to the lower hole (55b). In the present embodiment, the inner diameter of the compressor pipe (55), the diameter of the upper hole (55a), and the diameter of the lower hole (55b) are set as follows.

Inner diameter of compressor pipe (55)> Diameter of upper hole (55a)> Diameter of lower hole (55b) In the present embodiment, when the underground heat exchanger (50) is disposed obliquely, FIG. As shown in FIG. 3, it is preferable that the lubricating oil suction portion (that is, the filter (55c)) is located at the lowermost portion of the liquid layer.

<< Oil return by oil return mechanism (compressor piping (55)) >>
When the heating operation of the air conditioning system (1) is started, the gaseous refrigerant in the outer pipe 51 is opened at the end of the U-shaped pipe (compressor pipe (55)) in the outer pipe (51) (hereinafter, The compressor pipe (55) is entered through the lower hole (55b) (refer to FIG. 11B). That is, a gaseous refrigerant flow is formed in the compressor pipe (55). Here, for example, when the pressure in the outer pipe (51) is relatively low, such as when the air conditioning system (1) starts operation, if lubricating oil accumulates at the bottom of the outer pipe (51), The flow in (55) is dominated by the refrigerant sucked from the upper hole (55a).

  Further, when the pressure in the outer pipe (51) exceeds a certain level, the flow in the compressor pipe (55) is dominated by the refrigerant sucked from the opening end. Thus, when a flow is formed in the compressor pipe (55) by the refrigerant from the open end, the pressure near the lower hole (55b) in the compressor pipe (55) decreases, and the outer pipe ( 51) Lubricating oil collected at the bottom is sucked from the lower hole (55b). Thus, by returning the lubricating oil to the compressor (30), the compressor (30) can be stably operated.

<< Embodiment 5 of the Invention >>
The underground heat exchanger (50) can also be installed in the horizontal direction. Drawing 13 is a figure showing typically the state where the underground heat exchanger (50) was installed horizontally. As already mentioned, the stratum includes a layer mainly composed of earth and sand, a layer containing earth and sand, a layer mainly containing water, and a bedrock where rocks are continuously distributed. is there. This underground heat exchanger (50) may be installed in any formation or across a plurality of layers. In FIG. 13, Example 1 is installed in a layer formed only of earth and sand, Example 2 is installed in a layer containing earth and sand and water, Example 3 is installed in a layer mainly containing water, Example Examples 4 are installed on the bedrock.

  For example, when the underground heat exchanger (50) of Embodiment 3 is installed in the horizontal direction, as shown in FIG. 14, the cooling liquid pipe (56) and the oil return pipe (92) are installed. It is advisable to bend each tip on the lower side (that is, the side on which the refrigerant and lubricating oil accumulate due to gravity). By doing so, it becomes possible to reliably suck in the liquid refrigerant and lubricating oil accumulated in the outer pipe (51).

<< Modification of Embodiment 5 >>
An underground heat exchanger (50) that does not have an oil return mechanism (ejector (90)) can also be installed in the horizontal direction. When the ejector (90) is not provided in the outer pipe (51) as in the underground heat exchanger (50) of the first embodiment, for example, the cooling liquid pipe (56) is lowered in the installed state. If the tip is bent to the side and the cooling operation is temporarily performed while the heating operation is stopped or during the heating operation, the lubricating oil in the outer pipe (51) is transferred to the compressor (30). Can be returned. That is, during cooling operation, the refrigerant condenses in the underground heat exchanger (50) and accumulates at the bottom of the outer pipe (51), so that the lubricating oil is dissolved in the condensed refrigerant, and the molten lubricating oil Will return to the compressor (30) together with the refrigerant. Further, the lubricating oil may be separated at a stage before introducing the refrigerant into the underground heat exchanger (50).

Embodiment 6 of the Invention
In addition, the heat exchanger according to each of the above-described embodiments and modifications can be installed in water in addition to being installed in the ground. As specific installation locations, for example, the sea, lakes, ponds, pools, water tanks, rivers, sewers, etc. can be raised. FIG. 15 is a diagram schematically showing a state in which the heat exchanger (50) is installed in water. In this figure, six examples (Examples 1 to 6) are described as installation examples of the heat exchanger (50) (underwater heat exchanger). Examples 1 and 2 are examples in which a heat exchanger (50) is installed in a water tank or pool. In Example 1, the heat exchanger (50) is arranged vertically, and in Example 2, it is arranged horizontally. Examples 3 and 4 are examples in which the heat exchanger (50) is installed in the sea, lake, or pond. In Example 3, the heat exchanger (50) is arranged vertically, and in Example 4, the heat exchanger (50) is arranged horizontally. Moreover, Example 5 is an example which has arrange | positioned the heat exchanger (50) in the sewer, and has arrange | positioned in the horizontal direction. That is, also when installing in water, a heat exchanger (50) may be installed vertically and may be installed horizontally. Moreover, even when installing in water, it is also possible to incline and install a heat exchanger (50) (refer Example 6 of FIG. 15).

  Even when the heat exchanger (50) is installed in the water as described above, heat exchange is performed by the same mechanism as that of each of the above embodiments and modifications.

<< Other Embodiments >>
(Other configuration examples of the liquid pipe for heating (52))
The spraying means for the refrigerant is not limited to the spray hole (53). For example, as shown in FIG. 16, a nozzle (80) may be provided on the outer wall of the heating liquid pipe (52) as spraying means. The nozzle (80) determines the number, position, distance from the inner wall and the like so that the inner wall of the outer pipe (51) is wetted as uniformly as possible by the sprayed refrigerant.

(Other configuration examples of outer pipe (51))
Further, as shown in FIGS. 17A and 17B, a wick (81) may be provided on the inner wall of the outer tube (51). The wick (81) permeates and holds the liquid refrigerant sprayed by the spraying means such as the spray hole (53), and makes the held liquid refrigerant contact the inner wall of the outer pipe (51). Examples of such wicks (81) include metal porous bodies, porous ceramics, fiber aggregates, and the like. Thus, by providing the wick (81) on the inner wall of the outer pipe (51), it is possible to ensure uniform wetting with respect to the inner wall of the outer pipe (51), and in particular heat exchange during heating operation Performance is improved.

  Further, a plurality of grooves (82) may be provided on the inner wall of the outer tube (51) as shown in the cross-sectional view of FIG. Specifically, this groove (82) has a width, depth, number, etc. so as to hold the liquid refrigerant sprayed by the spraying means by utilizing the surface tension or reducing the contact angle on the inner surface. Determine. By providing such a groove (82) on the inner wall of the outer tube (51), the inner wall of the outer tube (51) can still be evenly wetted, especially during heat operation. Performance is improved.

  INDUSTRIAL APPLICATION This invention is useful as a heat exchanger installed in the ground or underwater, and an air conditioning system using the same.

1 Air-conditioning system 50 Ground heat exchanger 51 Outer pipe 52 Heating liquid pipe 53 Spray hole (spraying means)
56 Liquid tube for cooling 60 Switching valve 80 Nozzle (spraying means)
81 Wick 82 Groove 90 Ejector (oil return mechanism)

Claims (9)

A heat exchanger installed in the ground or in water,
An outer pipe (51) installed in the ground or in water, into which refrigerant in the refrigeration cycle is introduced ;
A heating liquid pipe (52) for introducing the refrigerant into the outer pipe (51) during heating operation in which the outer pipe (51) serves as an evaporator;
Spray means (53) for spraying the refrigerant introduced into the heating liquid pipe (52) onto the inner wall of the outer pipe (51);
During cooling operation in which the outer pipe (51) serves as a condenser, a cooling liquid pipe (56) for deriving the refrigerant condensed in the outer pipe (51) is provided.
The heat exchanger according to claim 1, wherein the cooling liquid pipe (56) extends to a lower end of the outer pipe (51) .
A heat exchanger characterized by that. The heat exchanger of claim 1 ,
The heat exchanger, wherein the spray means (53) is a plurality of spray holes (53) provided in the heating liquid pipe (52). The heat exchanger of claim 1 ,
The spray means (53) is a plurality of nozzles (80) provided in the heating liquid pipe (52). The heat exchanger of claim 1 ,
The heat exchanger according to claim 1, wherein the heating liquid pipe (52) is provided at a center of the outer pipe (51). The heat exchanger of claim 1 ,
In the outer pipe (51), a wick (81) is provided along the inner wall of the outer pipe (51). The heat exchanger of claim 1 ,
A heat exchanger, wherein a groove (82) for holding a refrigerant is formed on an inner wall of the outer pipe (51). The heat exchanger of claim 1 ,
The outer pipe (51) includes a compressor pipe (55) for leading the refrigerant in the outer pipe (51) to the compressor (30),
The compressor pipe (55) is provided with an oil return mechanism (90) for returning the lubricating oil accumulated at the bottom of the outer pipe (51) to the compressor (30). Exchanger. An air conditioning system comprising the heat exchanger according to claim 1 and performing a refrigeration cycle. A heat exchanger according to claim 1 ;
A switching valve (60) for switching so that the refrigerant is selectively introduced into either the heating liquid pipe (52) or the cooling liquid pipe (56);
An air conditioning system comprising a refrigerant circuit (10) for performing a refrigeration cycle.

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