KR100960196B1 - Refrigeration device - Google Patents

Abstract

The medium pressure heat exchanger 40 and the gas-liquid separator 51 are installed in the refrigerant circuit 20. In the cooling operation, a part of the refrigerant magnified by the outdoor heat exchanger 36 flows into the injection pipe 43. The refrigerant flowing into the injection pipe 43 is reduced to medium pressure when passing through the injection expansion valve 44, and then evaporated in the intermediate pressure heat exchanger 40, and then the intermediate pressure port 32 of the compressor 31. Is supplied. In the heating operation, the refrigerant condensed in the indoor heat exchanger 71 is reduced to a medium pressure when passing through the indoor expansion valve 72, and then flows into the gas-liquid separator 51. The intermediate pressure gas refrigerant in the gas-liquid separator 51 is supplied to the intermediate pressure port 32 of the compressor 31.

Refrigeration cycle, gas injection, connecting piping, supercooling, gas-liquid separator

Description

Freezer {REFRIGERATION DEVICE}

The present invention relates to a refrigeration apparatus for supplying a gas by supplying a medium-pressure gas refrigerant to the compressor.

Background Art Conventionally, a refrigeration apparatus is known that performs so-called gas injection (that is, an operation of supplying a medium pressure gas refrigerant to a compressor) for the purpose of reducing input to a compressor. For example, FIG. 1 of patent document 1 (Unexamined-Japanese-Patent No. 2001-033117) discloses supplying an intermediate pressure gas refrigerant to the compression chamber during compression in a compressor as a refrigeration apparatus which performs a one-stage compression refrigeration cycle. have. Further, Fig. 13 of Patent Document 1 discloses supplying an intermediate pressure gas refrigerant between a low stage compressor and a high stage compressor as a refrigeration apparatus that performs a two-stage compression refrigeration cycle.

In order to perform gas injection, a medium pressure gas refrigerant must be generated. To this end, for example, in the refrigerating device described in FIG. 1 of Patent Document 1, a gas-liquid separator for separating an intermediate pressure refrigerant into a liquid refrigerant and a gas refrigerant is provided in the refrigerant circuit, and the gas-pressure refrigerant is supplied from the gas-liquid separator to the compressor. To supply. Moreover, in the refrigeration apparatus of FIG. 9 of patent document 1, a medium pressure heat exchanger evaporates by heat-exchanging a medium pressure refrigerant with a high pressure liquid refrigerant, and supplies a medium pressure gas refrigerant from this medium pressure heat exchanger to a compressor.

[Initiation of invention]

[Problem to Solve Invention]

By the way, in the said refrigeration apparatus, the component apparatuses, such as a compressor and a heat exchanger, which are provided in a refrigerant | coolant circuit, may be arrange | positioned in mutually distant positions, or may be arrange | positioned with a different height. For example, an air conditioner, which is a kind of refrigeration device, is often configured by connecting an outdoor unit and an indoor unit by connecting pipes. When the air conditioner is installed in a building or the like, the length of the connecting pipe may be close to 100 m or there may be a height difference of about 20 to 30 m between the outdoor unit and the indoor unit.

As described above, the installation situation of the refrigerating device is various depending on the use thereof. And for the refrigeration apparatus which carries out the said gas injection, there exists a possibility that smooth operation may become impossible depending on the installation situation. This problem is described below.

As described above, in the refrigerating device which carries out gas injection, a medium pressure gas refrigerant may be supplied from the gas-liquid separator to the compressor. Since the liquid refrigerant and the gas refrigerant coexist in the gas-liquid separator, the liquid refrigerant sent out from the gas-liquid separator is saturated. When this type of refrigerating device cools the object, the saturated liquid refrigerant flowing out of the gas-liquid separator is sent to the use-side heat exchanger. However, if the utilization heat exchanger is far from the gas-liquid separator, or if the utilization-side heat exchanger is installed at a position higher than the gas-liquid separator, the refrigerant pressure decreases while flowing from the gas-liquid separator toward the utilization-side heat exchanger, causing a portion of the refrigerant to It may evaporate. Therefore, the flow rate of the liquid refrigerant into the utilization side heat exchanger decreases, so that the cooling capacity obtained from the utilization side heat exchanger may decrease.

In a refrigeration apparatus that performs gas injection, the intermediate pressure refrigerant may be exchanged with the high pressure liquid refrigerant in the intermediate pressure heat exchanger, and the intermediate pressure refrigerant evaporated in the intermediate pressure heat exchanger may be supplied to the compressor. When this type of refrigerating device heats the object, a part of the refrigerant condensed in the use-side heat exchanger is reduced to medium pressure and introduced into the medium pressure heat exchanger. However, if the medium pressure heat exchanger is far from the use side heat exchanger, or if the medium pressure heat exchanger is installed at a position higher than the use side heat exchanger, the refrigerant pressure decreases while flowing from the use side heat exchanger toward the medium pressure heat exchanger. As a result, some of the refrigerant evaporates and the refrigerant temperature may decrease. As a result, the temperature difference between the high pressure refrigerant and the intermediate pressure refrigerant that exchanges heat with each other in the intermediate pressure heat exchanger is small, and there is a concern that the intermediate pressure refrigerant cannot be gasified reliably in the intermediate pressure heat exchanger.

This invention is made | formed in view of such a point, Comprising: The so-called refrigeration apparatus which injects gas WHEREIN: It enables to operate smoothly irrespective of the installation situation and operation condition.

[Means for solving the problem]

In the first aspect of the present invention, the compressors 31 and 34, the heat source side heat exchanger 36, and the use side heat exchanger 71 are connected to perform a refrigeration cycle, and the heat source side heat exchanger 36 is a condenser. A refrigerant circuit 20 capable of switching between a cooling operation in which the utilization side heat exchanger 71 becomes an evaporator and a heating operation in which the utilization side heat exchanger 71 becomes a condenser and the heat source side heat exchanger 36 becomes an evaporator. It aims at the refrigeration apparatus provided. The refrigerant circuit 20 includes an injection passage 43 for supplying the intermediate pressure refrigerant obtained by depressurizing a part of the high pressure liquid refrigerant to the compressors 31 and 34, and the injection passage 43 with the compressor 31. , The medium pressure heat exchanger 40 for evaporating the intermediate pressure refrigerant flowing toward the high pressure liquid refrigerant and evaporating the medium pressure refrigerant, and the gas-liquid separator for separating the medium pressure refrigerant obtained by depressurizing the high pressure liquid refrigerant into the liquid refrigerant and the gas refrigerant (51). Medium pressure gas refrigerant flowing through the injection passage 43 during the cooling operation, and medium pressure gas refrigerant flowing out from the gas-liquid separator 51 during the heating operation to the compressors 31 and 34, respectively. The refrigerant distribution path is configured to be changed to be supplied.

In the first invention, the supply source of the medium pressure refrigerant to the compressors 31 and 34 is changed during the cooling operation and during the heating operation. During the cooling operation, the medium pressure refrigerant evaporated in the medium pressure heat exchanger 40 is supplied to the compressors 31 and 34. At this time, in the intermediate pressure heat exchanger 40, since the high pressure liquid refrigerant is cooled by heat exchange with the medium pressure refrigerant, the supercooling degree of the high pressure liquid refrigerant is increased. Therefore, even if the pressure of the high pressure refrigerant decreases to some extent between the medium pressure heat exchanger 40 and the use side heat exchanger 71, the high pressure refrigerant supplied to the use side heat exchanger 71 is maintained in a liquid state or used. In the high pressure refrigerant supplied to the side heat exchanger (71), the amount of evaporation is reduced. On the other hand, during the heating operation, the medium pressure refrigerant is introduced into the gas-liquid separator 51, and the gas refrigerant in the gas-liquid separator 51 is supplied to the compressors 31 and 34. As a result, even if a part of the refrigerant evaporates due to a decrease in the refrigerant pressure between the use-side heat exchanger 71 and the gas-liquid separator 51 to some extent, the gas-liquid separator 51 separates the gas refrigerant and the liquid refrigerant. 31 and 34 are supplied with a medium-pressure gas refrigerant reliably.

According to a second aspect of the present invention, the refrigerant circuit (20) includes a heat source side circuit (30) provided with the compressors (31, 34) and the heat source side heat exchanger (36) and the utilization side heat exchanger ( 71 is provided by connecting the use-side circuit 70 is connected to the connecting pipe (21, 22), the injection passage 43, the intermediate pressure heat exchanger 40, and the gas-liquid separator 51 is the heat source It is provided in the side circuit 30.

In the second invention, the refrigerant circuit 20 is composed of a heat source side circuit 30, a use side circuit 70, and connection pipes 21 and 22. During the cooling operation, the high pressure liquid refrigerant cooled when passing through the intermediate pressure heat exchanger 40 flows into the use-side heat exchanger 71 through the connecting pipe 21. Therefore, even when the connecting pipes 21 and 22 are long or when the use side circuit 70 is installed at a position higher than the heat source side circuit 30, the high pressure refrigerant supplied to the use side heat exchanger 71 is in a liquid state. The amount of evaporated in the middle of the high pressure refrigerant which is maintained at or supplied to the use-side heat exchanger 71 is reduced. On the other hand, during the heating operation, the refrigerant condensed in the use-side heat exchanger (71) flows into the gas-liquid separator (51) through the connecting pipe (21), and the gas refrigerant in the gas-liquid separator (51) goes to the compressors (31, 34). Supplied. As a result, even when the connecting pipes 21 and 22 are long or when the heat source side circuit 30 is provided at a position higher than the use side circuit 70, the gas refrigerant is reliably supplied to the compressors 31 and 34. .

According to a third aspect of the present invention, in the first invention, the gas-liquid separator (51) becomes a downstream side of the heat source side heat exchanger (36) during the cooling operation of the refrigerant circuit (20). The intermediate pressure heat exchanger 40 is housed inside the vessel-shaped member 65 and is injected by the vessel-shaped member 65 disposed at a position to be downstream of the side heat exchanger 71. The medium pressure refrigerant flowing through the passage 43 is constituted by a heat exchange member 66 for exchanging heat with the liquid refrigerant in the container-type member 65.

In the third invention, the gas-liquid separator 51 is constituted by the vessel-shaped member 65, and the medium pressure heat exchanger 40 is constituted by the heat exchange member 66. In the cooling operation, the refrigerant (high pressure liquid refrigerant) condensed in the heat source side heat exchanger 36 flows into the vessel-like member 65. In addition, a part of the high pressure liquid refrigerant flows into the injection passage 43, and is decompressed to an intermediate pressure and flows into the heat exchange member. The medium pressure refrigerant introduced into the heat exchange member is exchanged with the high pressure liquid refrigerant in the vessel-shaped member 65 to evaporate, and then supplied to the compressors 31 and 34. The high pressure liquid refrigerant in the vessel-shaped member 65 cooled by heat exchange with the intermediate pressure refrigerant is sent out from the vessel-shaped member 65 toward the use-side heat exchanger 71. On the other hand, in the heating operation, the refrigerant condensed by the use-side heat exchanger 71 is introduced into the container-type member 65 after being decompressed to an intermediate pressure. In the container-type member 65, the introduced medium pressure refrigerant is separated into a liquid refrigerant and a gas refrigerant. The liquid refrigerant is sent from the heat source side heat exchanger 36 toward the heat source side heat exchanger 36, and the gas refrigerant is supplied to the compressors 31 and 34 through the injection passage 43.

The fourth invention relates to a low pressure refrigerant obtained by depressurizing a part of the high pressure liquid refrigerant to a low pressure at a position on the downstream side of the intermediate pressure heat exchanger 40 during the cooling operation in the first invention. The subcooling heat exchanger 60 for cooling the high pressure liquid refrigerant by heat exchange is to be installed.

In the fourth invention, the subcooled heat exchanger 60 is provided in the refrigerant circuit 20. In the subcooling heat exchanger (60) during the cooling operation, the high pressure liquid refrigerant passing through the intermediate pressure heat exchanger (40) is cooled by heat exchange with a low pressure refrigerant obtained by depressurizing a part of the high pressure liquid refrigerant. That is, in the subcooling heat exchanger (60), the subcooling degree of the high pressure liquid refrigerant increases. The high pressure liquid refrigerant cooled in the subcooling heat exchanger 60 is sent to the use-side heat exchanger 71.

According to a fifth aspect of the present invention, in the refrigerant circuit (20), a one-stage compression refrigeration cycle is performed, while the compressor (31) is configured such that an intermediate pressure gas refrigerant flows into a compression chamber during compression.

In the fifth invention, the medium pressure gas refrigerant is introduced into the compression chamber during compression in the compressor 31. The compressor 31 is a low pressure refrigerant evaporated from the use side heat exchanger 71 and the heat source side heat exchanger 36 as an evaporator, and an intermediate pressure supplied from the medium pressure heat exchanger 40 or the gas-liquid separator 51. Inhale and compress the refrigerant.

In the sixth invention, in the refrigerant circuit (20), in the refrigerant circuit (20), the low stage compressor (33) and the high stage compressor (34) are connected in series, and a two stage compression refrigeration cycle is performed. 20 is configured to supply a medium pressure gas refrigerant to the suction side of the high stage compressor 34.

In the sixth invention, the medium pressure gas refrigerant is introduced into the suction side of the high stage compressor (34). The high stage compressor 34 sucks the refrigerant compressed by the low stage compressor 33 and the gas refrigerant sent out from the medium pressure heat exchanger 40 or the gas-liquid separator 51.

[Effects of the Invention]

In the present invention, during the cooling operation, the intermediate pressure refrigerant evaporated in the intermediate pressure heat exchanger (40) is supplied to the compressors (31, 34), and the high pressure liquid refrigerant cooled in the intermediate pressure heat exchanger (40) is used for the use side heat exchanger ( 71). Thus, the use side heat exchanger 71 is disposed at a position far from the medium pressure heat exchanger 40, or the use side heat exchanger 71 is disposed at a position higher than the medium pressure heat exchanger 40, thereby providing a medium pressure heat exchanger. Even in the installation situation in which the pressure of the high pressure refrigerant is very low between the gas 40 to the use side heat exchanger 71, the high pressure refrigerant supplied to the use side heat exchanger 71 is kept in the liquid state or the use side is used. In the high pressure refrigerant supplied to the heat exchanger 71, the amount of evaporation on the way can be reduced. As a result, the amount of liquid refrigerant supplied to the use-side heat exchanger 71 during the cooling operation can be ensured, and the cooling capacity of the use-side heat exchanger 71 can be sufficiently exhibited.

In the present invention, the gas refrigerant of medium pressure is supplied from the gas-liquid separator 51 to the compressors 31 and 34 during the heating operation. As a result, the gas-liquid separator 51 is disposed at a position far from the use-side heat exchanger 71, or the gas-liquid separator 51 is disposed at a position higher than the use-side heat exchanger 71, so that the use-side heat exchanger 71 is disposed. The medium pressure gas refrigerant can be reliably supplied to the compressors 31 and 34 even in an installation situation in which the pressure of the refrigerant is very low between the gas liquid separator 51 and the gas liquid separator 51. As a result, the situation that the medium pressure liquid refrigerant flows into the compressors 31 and 34 and causes damage to the compressors 31 and 34 can be avoided.

As described above, according to the present invention, even when the refrigerating device 10 is installed in any state, the freezing device 10 can be smoothly operated both during the cooling operation and during the heating operation.

In the second invention, the refrigerant circuit 20 is composed of the heat source side circuit 30, the use side circuit 70, and the connection pipes 21 and 22. In this case, the heat source side circuit 30 provided with the intermediate pressure heat exchanger 40 or the gas-liquid separator 51, and the use side circuit 70 provided with the use side heat exchanger 71 are disposed at a distant position, or both. Are often installed at different heights. Therefore, in the refrigerating device 10 having the refrigerant circuit 20 having the same configuration as that of the present invention, if the supply source of the medium pressure refrigerant to the compressors 31 and 34 is changed during the cooling operation and the heating operation as described above, Constraints regarding the installation of the device 10 can be relaxed.

In the third invention, the heat exchange member 66 constituting the intermediate pressure heat exchanger 40 is housed inside the vessel-shaped member 65 constituting the gas-liquid separator 51. That is, when the container type member 65 in which the heat exchange member 66 is housed is connected to the refrigerant circuit 20, both the gas-liquid separator 51 and the medium pressure heat exchanger 40 are installed in the refrigerant circuit 20. It becomes one. Therefore, according to this invention, the structure of the refrigerant circuit 20 can be simplified compared with the case where the gas-liquid separator 51 and the intermediate pressure heat exchanger 40 are separately formed.

In the fourth aspect of the invention, the subcooling heat exchanger (60) is provided in the refrigerant circuit (20), and the supercooling degree of the high pressure liquid refrigerant sent to the use-side heat exchanger (71) during the cooling operation is increased. As a result, even in an installation situation in which the pressure of the high pressure refrigerant decreases to some extent between the intermediate pressure heat exchanger 40 and the use side heat exchanger 71, the high pressure refrigerant supplied to the use side heat exchanger 71 is more reliably provided. It is possible to further reduce the amount of evaporation in the middle of the high pressure refrigerant supplied to the use-side heat exchanger 71 or maintained in the liquid state.

1 is a piping system diagram showing the configuration of a refrigerant circuit of an air conditioner in the first embodiment, (A) shows a state during cooling operation, and (B) shows a state during heating operation.

Fig. 2 is a piping system diagram showing the configuration of the refrigerant circuit of the air conditioner in the second embodiment, (A) shows the state during the cooling operation, and (B) shows the state during the heating operation.

3 is a piping system diagram showing the configuration of the refrigerant circuit of the air conditioner according to the first modification of the other embodiment, (A) shows the state during the cooling operation, and (B) shows the state during the heating operation.

Fig. 4 is a piping system diagram showing the configuration of the refrigerant circuit of the air conditioner in the second modification of the other embodiment, (A) shows the state during the cooling operation, and (B) shows the state during the heating operation.

[Description of the code]

20: refrigerant circuit 21: liquid side connection piping

22 gas connection pipe 30 outdoor circuit (heat source side circuit)

31 compressor 33 low stage compressor

34: high stage compressor 36: outdoor heat exchanger (heat source side heat exchanger)

40: medium pressure heat exchanger 43: injection pipe (injection passage)

51: gas-liquid separator 65: container type member

66: heat exchange member 70: indoor circuit (use circuit)

71: indoor heat exchanger (use side heat exchanger)

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]

A first embodiment of the present invention will be described. This embodiment is the air conditioner 10 comprised by the refrigeration apparatus which concerns on this invention.

As shown in FIG. 1, the air conditioner 10 of the present embodiment includes one outdoor unit 11 and two indoor units 12. The number of indoor units 12 is merely an example. The outdoor unit 11 accommodates an outdoor circuit 30 which is a heat source side circuit 30. Each indoor unit 12 accommodates an indoor circuit 70 which is a use side circuit.

In the air conditioner 10, the refrigerant circuit 20 is formed by connecting the outdoor circuit 30 and the indoor circuit 70 to the liquid side connection pipe 21 and the gas side connection pipe 22. In this refrigerant circuit 20, two indoor circuits 70 are connected to one outdoor circuit 30 in parallel with each other.

Each indoor circuit 70 is provided with one indoor heat exchanger 71 and one indoor expansion valve 72 serving as heat exchangers on the use side. The indoor heat exchanger 71 is an air heat exchanger that heat-exchanges indoor air and a refrigerant. In each indoor circuit 70, the indoor heat exchanger 71 and the indoor expansion valve 72 are connected in series with each other. In each indoor circuit 70, a liquid side connection pipe 21 is connected to an end portion of the indoor expansion valve 72, and a gas side connection pipe 22 is connected to an end portion of the indoor heat exchanger 71.

The outdoor circuit 30 is provided with a compressor 31, a four-way valve 35, an outdoor heat exchanger 36 serving as a heat source side heat exchanger, an outdoor expansion valve 37, and an accumulator 38. In addition, the outdoor heat exchanger 36 is provided with an intermediate pressure heat exchanger 40, a gas-liquid separator 51, a bypass pipe 50, an injection pipe 43, and an intermediate pressure gas pipe 52.

The compressor 31 is a volumetric compressor 31 and is configured to compress the refrigerant sucked into the compression chamber. The compressor 31 is provided with an intermediate pressure port 32 for introducing an intermediate pressure refrigerant into the compression chamber during compression. The compressor 31 has a discharge side connected to a first port of the four-way valve 35 and a suction side connected to a second port of the four-way valve 35 via the accumulator 38. In this embodiment, only one compressor 31 is provided in the outdoor circuit 30, but a plurality of compressors may be provided in parallel.

The outdoor heat exchanger 36 is an air heat exchanger that heat-exchanges outdoor air and a refrigerant. The intermediate pressure heat exchanger 40 is a heat exchanger for exchanging refrigerants such as a double tube exchanger or a plate heat exchanger with each other. The intermediate pressure heat exchanger 40 is provided with a first flow passage 41 and a second flow passage 42. The outdoor heat exchanger 36 has one end connected to the third port of the four-way valve 35 and the other end connected to one end of the first flow passage 41 of the intermediate pressure heat exchanger 40 via the outdoor expansion valve 37. do. The other end of the intermediate pressure heat exchanger 40, the first flow passage 41, is connected to the liquid side connection pipe 21 via the first check valve 45. The first check valve 45 is arranged to allow only the circulation of the refrigerant from the intermediate pressure heat exchanger 40 to the liquid side connection pipe 21.

Injection pipe 43 forms an injection passage. The injection pipe 43 has a start end connected between the intermediate pressure heat exchanger 40 and the first check valve 45 and an end connected to the intermediate pressure port 32 of the compressor 31, respectively. The second flow passage 42 of the medium pressure heat exchanger 40 is arranged in the middle of the injection pipe 43. The injection pipe 43 is provided with an injection expansion valve 44 between the start end and the second pressure passage 42 of the intermediate pressure heat exchanger 40.

The gas-liquid separator 51 is a hermetically sealed container formed in a vertically long cylindrical shape. The gas-liquid separator 51 is arranged at the lower end in the middle of the bypass pipe 50. The bypass pipe 50 has a start end between the first check valve 45 and the liquid side connection pipe 21, and the end of the bypass pipe 50 and the outdoor expansion valve 37 of the intermediate pressure heat exchanger 40. Are connected respectively. In the bypass pipe 50, a second check valve 55 is provided between the start end and the gas-liquid separator 51. The second check valve 55 is arranged to allow only refrigerant flow in the direction flowing out of the gas-liquid separator 51.

One end of the intermediate pressure gas pipe 52 is connected to the top of the gas-liquid separator 51. The other end of the intermediate pressure gas pipe 52 is connected between the second flow path 42 of the intermediate pressure heat exchanger 40 and the compressor 31 in the injection pipe 43. An electromagnetic valve 53 is provided in the middle of the intermediate pressure gas pipe 52.

As described above, the four-way valve 35 has a first port connected to the discharge side of the compressor 31, a second port connected to the accumulator 38, and a third port connected to the outdoor heat exchanger 36. The fourth port of the four-way valve 35 is connected to the gas side connecting pipe 22. The four-way valve 35 has a first state (state shown in FIG. 1A) 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, and the first port and the fourth port. The port is in communication with the second port and the third port is in communication with the second state (state shown in Fig. 1B).

Operation operation

In the air conditioner (10) is configured to switch between the cooling operation and heating operation.

<Cooling operation>

The operation operation in the cooling operation will be described with reference to FIG. In the refrigerant circuit 20 during the cooling operation, the refrigerant circulates so that the outdoor heat exchanger 36 becomes a condenser and the indoor heat exchanger 71 becomes an evaporator. That is, the cooling circuit 20 performs the cooling operation.

Specifically, the four-way valve 35 is set to the first state during the cooling operation. In addition, the outdoor expansion valve 37 is set to the fully open state, the opening degree of the injection expansion valve 44 and the indoor expansion valve 72 is appropriately adjusted, respectively, and the solenoid valve 53 is closed.

The high pressure gas refrigerant discharged from the compressor 31 is condensed by radiating heat to outdoor air in the outdoor heat exchanger 36. The high pressure liquid refrigerant discharged from the outdoor heat exchanger 36 radiates heat to the refrigerant in the second flow passage 42 while passing through the first flow passage 41 of the intermediate pressure heat exchanger 40. Part of the high pressure liquid refrigerant flowing out of the first flow passage 41 of the intermediate pressure heat exchanger 40 flows into the injection pipe 43, and the remainder of each of the indoor circuits 70 through the liquid side connection pipe 21. To be distributed.

In each of the indoor circuits 70, the high pressure liquid refrigerant introduced therein is depressurized when passing through the indoor expansion valve 72, and then is absorbed from the indoor air in the indoor heat exchanger 71 to evaporate. The refrigerant evaporated in the indoor heat exchanger (71) is returned to the outdoor circuit (30) through the gas side connection pipe (22), and is sucked into the compressor (31) through the accumulator (38).

On the other hand, the high pressure liquid refrigerant introduced into the injection pipe 43 is reduced to a medium pressure when passing through the injection expansion valve 44 to be a medium pressure refrigerant in the gas-liquid two-phase state. The intermediate pressure refrigerant absorbs heat from the refrigerant in the first flow path 41 and evaporates while flowing through the second flow path 42 of the intermediate pressure heat exchanger 40. The intermediate pressure gas refrigerant discharged from the second flow path 42 of the intermediate pressure heat exchanger 40 is sent to the intermediate pressure port 32 of the compressor 31.

The compressor 31 sucks low pressure refrigerant into a compression chamber through the accumulator 38 and compresses it. In addition, the medium pressure gas refrigerant introduced from the medium pressure port 32 is introduced into the compression chamber during the compression. And the compressor 31 compresses and discharges the refrigerant | coolant in a compression chamber to high pressure.

In this way, during the cooling operation, the high pressure liquid refrigerant, which is cooled when passing through the intermediate pressure heat exchanger 40 and has a large subcooling degree, is sent to the indoor circuit 70 through the liquid side connection pipe 21. As a result, the length of the liquid-side connecting pipe 21 is greater than or equal to a certain degree, or the indoor circuit 70 is disposed at a position higher than or equal to a certain degree or higher than the outdoor circuit 30, and the liquid-side connecting pipe 21 is removed from the outdoor circuit 30. The high pressure refrigerant flowing into the indoor circuit 70 enters the liquid single phase state even when a part of the high pressure liquid refrigerant evaporates while reaching the indoor circuit 70 because the liquid refrigerant sent out to the indoor circuit 70 is saturated. maintain. In addition, even if a part of the high pressure liquid refrigerant evaporates while reaching the indoor circuit 70, the high pressure liquid refrigerant that evaporates compared to the case where the liquid refrigerant sent from the outdoor circuit 30 to the liquid side connection pipe 21 is saturated. The amount of decreases.

<Heating operation>

An operation operation during heating operation will be described with reference to FIG. 1B. In the refrigerant circuit 20 during the heating operation, the refrigerant circulates so that the indoor heat exchanger 71 becomes a condenser and the outdoor heat exchanger 36 becomes an evaporator. That is, the heating operation is performed in the refrigerant circuit 20.

Specifically, the four-way valve 35 is set to the second state during the heating operation. Moreover, the opening degree of the outdoor expansion valve 37 and the indoor expansion valve 72 is set suitably, the injection expansion valve 44 is set to a fully closed state, and the solenoid valve 53 is opened.

The high pressure gas refrigerant discharged from the compressor 31 is distributed to each indoor circuit 70 through the gas side connection pipe 22. In the indoor heat exchanger (71) of each indoor circuit (70), the high pressure gas refrigerant radiates heat to indoor air to condense. In each indoor circuit 70, the refrigerant flowing out of the indoor heat exchanger 71 is decompressed when passing through the indoor expansion valve 72 to become an intermediate pressure refrigerant in a gas-liquid two-phase state. The medium pressure refrigerant flowing out of each indoor circuit 70 is returned to the outdoor circuit 30 through the liquid side connection pipe 21 and flows into the gas-liquid separator 51 through the bypass pipe 50.

In the medium pressure refrigerant introduced into the gas-liquid separator 51, liquid refrigerant accumulates in the lower portion of the gas-liquid separator 51, and gas refrigerant accumulates in the upper portion of the gas-liquid separator 51. The medium pressure liquid refrigerant in the gas-liquid separator 51 again flows through the bypass pipe 50 and is introduced into the outdoor heat exchanger 36 after being decompressed when passing through the outdoor expansion valve 37. In the outdoor heat exchanger (36), the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger 36 is sucked into the compressor 31 through the accumulator 38. On the other hand, the medium pressure gas refrigerant in the gas-liquid separator 51 passes through the intermediate pressure gas pipe 52 and the injection pipe 43 in order and is introduced into the intermediate pressure port 32 of the compressor 31.

The compressor 31 sucks the low pressure refrigerant into the compression chamber through the accumulator 38 and compresses it. Moreover, the medium pressure gas refrigerant which flowed in from the intermediate pressure port 32 is introduce | transduced into the compression chamber in the middle of compression. And the compressor 31 compresses and discharges the refrigerant | coolant in a compression chamber to high pressure.

In this way, during the heating operation, the refrigerant returned to the outdoor circuit 30 through the liquid side connection pipe 21 is introduced into the gas-liquid separator 51 to be separated into a liquid refrigerant and a gas refrigerant, and only the gas refrigerant in the gas-liquid separator 51 is used. It is supplied to the intermediate pressure port 32 of the compressor 31. That is, even if the refrigerant flowing into the outdoor circuit 30 is in the gas-liquid two-phase state, only the gas refrigerant is reliably supplied to the intermediate pressure port 32 of the compressor 31. As a result, even when a part of the refrigerant is evaporated while reaching the indoor circuit 70 at a position where the length of the liquid-side connecting pipe 21 is higher than a certain degree, the intermediate pressure port 32 of the compressor 31 is provided. The refrigerant flowing into is maintained in the gas single phase state.

Effect of the first embodiment

During the cooling operation of the air conditioner 10, the medium pressure refrigerant evaporated in the intermediate pressure heat exchanger 40 is supplied to the intermediate pressure port 32 of the compressor 31, and the high pressure cooled in the intermediate pressure heat exchanger 40 is maintained. The liquid refrigerant is supplied to the indoor circuit 70. Accordingly, the liquid side connecting pipe 21 connecting the outdoor circuit 30 and the indoor circuit 70 is very long, or the indoor circuit 70 is disposed at a position higher than the outdoor circuit 30, so that the liquid side connecting pipe 21 is disposed. Even in an installation situation in which the refrigerant pressure is drastically lowered during the flow, the high pressure refrigerant supplied to the indoor circuit 70 is kept in a liquid state or evaporated in the middle of the high pressure refrigerant supplied to the indoor circuit 70. You can cut down the quantity. As a result, the amount of liquid refrigerant supplied to the indoor circuit 70 during the cooling operation can be ensured, and the cooling capacity of the indoor unit 12 can be sufficiently exhibited.

Here, when the plurality of indoor circuits 70, such as the air conditioner 10, are connected in parallel to each other, in order to appropriately adjust the cooling capacity of each indoor unit 12, the indoor expansion valve of each indoor circuit 70 ( 72) by controlling the opening degree separately to adjust the refrigerant distribution ratio to the indoor circuit (70). However, when the refrigerant passing through the indoor expansion valve 72 is in the gas-liquid two-phase state, the flow rate characteristics of the indoor expansion valve 72 become unstable, so that the distribution ratio of the refrigerant to each indoor circuit 70 cannot be properly controlled. There is concern. On the other hand, in the air conditioner 10 of this embodiment, it becomes easy to hold | maintain the refrigerant | coolant which flows into the indoor circuit 70 at the time of cooling operation in a liquid state. Therefore, according to this embodiment, in the air conditioner 10 provided with the some indoor unit 12, it becomes possible to control the cooling ability of each indoor unit 12 accurately.

During the heating operation of the air conditioner 10, the refrigerant returned from the indoor circuit 70 to the outdoor circuit 30 is separated into a liquid refrigerant and a gas refrigerant in the gas-liquid separator 51, and the compressor (from the gas-liquid separator 51). 31) supply only medium pressure gas refrigerant. As a result, the liquid side connecting pipe 21 connecting the outdoor circuit 30 and the indoor circuit 70 is very long, or the outdoor circuit 30 is disposed at a position higher than the indoor circuit 70, so that the liquid side connecting pipe 21 is closed. Even in an installation situation in which the pressure of the coolant drops significantly while flowing, only the gas coolant can be reliably supplied to the intermediate pressure port 32 of the compressor 31. As a result, the situation that the medium pressure liquid refrigerant flows into the compressor 31 and causes damage to the compressor 31 can be avoided.

Thus, according to this embodiment, even if the air conditioner 10 is installed in any state, it becomes possible to operate the air conditioner 10 smoothly in both a cooling operation and a heating operation.

<< 2nd embodiment >>

A second embodiment of the present invention will be described. This embodiment adds the subcooling heat exchanger 60 and the subcooling piping 63 to the air conditioner 10 of the said 1st Embodiment. Here, the difference from the said 1st Embodiment is demonstrated about the air conditioner 10 of this embodiment.

As shown in FIG. 2, the subcooled heat exchanger 60 is provided in the outdoor circuit 30. The supercooled heat exchanger 60 is a heat exchanger which heat-exchanges refrigerants such as a double tube heat exchanger and a plate heat exchanger. The supercooling heat exchanger 60 is provided with a first flow passage 61 and a second flow passage 62. The first flow path 61 of the subcooled heat exchanger 60 is formed between the intermediate pressure heat exchanger 40 and the first check valve 45 in the outdoor circuit 30.

In the supercooling pipe 63, a start end is connected between the subcooling heat exchanger 60 and the first check valve 45, and an end thereof is connected between the accumulator 38 and the four-way valve 35. The second flow path 62 of the subcooling heat exchanger 60 is disposed in the middle of the subcooling pipe 63. The subcooling piping 63 is provided with a subcooling expansion valve 64 between the start end and the subcooling 62 of the subcooling heat exchanger 60.

Operation operation

<Cooling operation>

As shown in Fig. 2A, the refrigerant circulates in the refrigerant circuit 20 during the cooling operation as in the case of the first embodiment. Specifically, the high pressure liquid refrigerant flowing out of the intermediate pressure heat exchanger 40 passes through the subcooling heat exchanger 60 and then flows into the liquid side connection pipe 21, and a part of the high pressure liquid refrigerant is a subcooling pipe ( Only the point flowing into 63) is different from the refrigerant circulation path in the first embodiment.

In the air conditioner 10 cooling operation of this embodiment, the opening degree of the subcooling expansion valve 64 is adjusted suitably. The high pressure liquid refrigerant flowing out of the first flow path 41 of the intermediate pressure heat exchanger 40 radiates heat to the refrigerant in the second flow path 62 while passing through the first flow path of the subcooled heat exchanger 60. A portion of the high pressure liquid refrigerant flowing out of the first flow path of the subcooling heat exchanger 60 flows into the subcooling pipe 63, and the remainder is distributed to each indoor circuit 70 through the liquid side connection pipe 21. That is, the indoor circuit 70 is supplied with a high pressure liquid refrigerant cooled by both the intermediate pressure heat exchanger 40 and the subcooled heat exchanger 60.

On the other hand, the high-pressure liquid refrigerant introduced into the subcooling heat exchanger 60 is reduced to low pressure when passing through the subcooling expansion valve 64 to become a low-pressure refrigerant in the gas-liquid two-phase state. The low pressure refrigerant absorbs and evaporates from the refrigerant in the first flow passage 61 while flowing in the second flow passage 62 of the subcooled heat exchanger 60. The low pressure gas refrigerant flowing out from the second flow path 62 of the subcooled heat exchanger 60 is combined with the low pressure refrigerant returned from the indoor circuit 70 to the outdoor circuit 30 through the gas side connection pipe 22. 31).

<Heating operation>

As shown in FIG. 2B, in the refrigerant circuit 20 during the heating operation, the refrigerant circulates as in the case of the first embodiment. Specifically, the subcooled expansion valve 64 is completely closed during the heating operation. The medium pressure refrigerant introduced into the outdoor circuit 30 from the liquid side connection pipe 21 passes through the bypass pipe 50 and enters the gas-liquid separator 51, and is separated into a liquid refrigerant and a gas refrigerant.

Effects of the Second Embodiment

In this embodiment, the subcooling heat exchanger 60 is provided in the outdoor circuit 30, and the superheat degree of the high pressure liquid refrigerant supplied to the indoor circuit 70 during the cooling operation is increased. Thus, even in an installation situation in which the pressure of the high pressure refrigerant decreases between the outdoor circuit 30 and the indoor circuit 70, the high pressure refrigerant supplied to the indoor circuit 70 is more reliably maintained in the liquid state or indoors. Among the high pressure refrigerants supplied to the circuit 70, the amount of evaporation that occurs in the middle can be further reduced.

<< other embodiment >>

It is good also as a following structure about the said embodiment.

First Modified Example

In each of the above embodiments, the gas-liquid separator 51 and the intermediate pressure heat exchanger 40 may be integrated. Here, the application of the present modification to the air conditioner 10 of the second embodiment will be described with reference to FIG. 3.

The gas-liquid separator 51 of this modification is comprised with the container member 65 formed in the slightly long cylinder shape. The bottom portion of the container-like member 65 constituting the gas-liquid separator 51 is connected to a portion between the outdoor expansion valve 37 and the subcooling heat exchanger 60 in the outdoor circuit 30. In the outdoor circuit 30 of the present modification, the bypass pipe 50, the first check valve 45, and the second check valve 55 are omitted.

Inside the vessel-shaped member 65, the heat exchange member 66 which shape | molded the heat exchanger tube in the coil spring shape is provided. The heat exchange member 66 is disposed at the bottom of the vessel-like member 65 so as to be immersed in the liquid refrigerant accumulated in the vessel-like member 65. The heat exchange member 66 is disposed downstream of the injection expansion valve 44 of the injection pipe 43. In this modification, this heat exchange member 66 constitutes the medium pressure heat exchanger 40.

The operation during the cooling operation will be described. In the cooling operation, as in the case of the second embodiment, the opening degree of the injection expansion valve 44 and the subcooling expansion valve 64 is appropriately adjusted, and the solenoid valve 53 is closed.

In the cooling operation, the refrigerant condensed in the outdoor heat exchanger 36 flows into the container-type member 65 through the outdoor expansion valve 37 in a fully open state. The high pressure liquid refrigerant in the vessel-shaped member 65 radiates heat to the medium pressure refrigerant flowing in the heat exchange member 66. That is, in the container type member 65, the high pressure liquid refrigerant is cooled by heat exchange with the intermediate pressure refrigerant in the heat exchange member 66, and the supercooling degree of the high pressure liquid refrigerant is increased. The high pressure liquid refrigerant cooled in the vessel-like member 65 flows in part into the inlet pipe 43 and is cooled again while the rest passes through the first flow path 61 of the supercooled heat exchanger 60.

The high pressure liquid refrigerant cooled by the subcooling heat exchanger 60 is supplied to the indoor circuit 70 through the liquid side connection pipe 21. On the other hand, the high pressure liquid refrigerant introduced into the injection pipe 43 is reduced to a medium pressure when passing through the injection expansion valve 44, and becomes a medium pressure refrigerant is sent to the heat exchange member (66). The medium pressure refrigerant introduced into the heat exchange member 66 is absorbed from the high pressure liquid refrigerant in the vessel-like member 65 and evaporated, and then is supplied to the intermediate pressure port 32 of the compressor 31.

The operation during the heating operation will be described. In the heating operation, the injection expansion valve 44 and the subcooling expansion valve 64 are completely closed as in the case of the second embodiment, and the solenoid valve 53 is opened.

In the heating operation, the refrigerant condensed in the indoor heat exchanger (71) is decompressed to an intermediate pressure when passing through the indoor expansion valve (71), and then the first flow path of the liquid side connection pipe (21) and the subcooled heat exchanger (60) ( 61 is passed in order to enter the container-like member (65). In the vessel-shaped member 65, the medium pressure refrigerant in the gas-liquid two-phase state is separated into a liquid refrigerant and a gas refrigerant. The medium pressure gas refrigerant accumulated in the upper portion of the container-type member 65 is supplied to the intermediate pressure port 32 of the compressor 31 through the injection pipe 43. In addition, the medium pressure liquid refrigerant accumulated in the lower portion of the container-type member 65 is introduced into the outdoor heat exchanger 36 after the pressure is reduced to low pressure when passing through the outdoor expansion valve 37.

As mentioned above, in this modification, the heat exchange member 66 which comprises the intermediate pressure heat exchanger 40 is accommodated in the container type member 65 which comprises the gas-liquid separator 51. As shown in FIG. That is, when the container type member 65 which accommodates the heat exchange member 66 therein is connected to the outdoor circuit 30, both the gas-liquid separator 51 and the medium pressure heat exchanger 40 are connected to the outdoor circuit 30. It is installed. Therefore, according to this modification, the structure of the outdoor circuit 30 can be simplified compared with the case where the gas-liquid separator 51 and the intermediate pressure heat exchanger 40 are separately formed.

Second Modified Example

In each of the above embodiments, the low stage compressor 33 and the high stage compressor 34 may be provided in the outdoor circuit 30 so as to perform the two stage compression refrigeration cycle in the refrigerant circuit 20. Here, with reference to FIG. 4, it demonstrates applying this modification to the air conditioner 10 of the said 2nd Embodiment.

In the outdoor circuit 30 of this modification, the low stage compressor 33 and the high stage compressor 34 are connected in series. Specifically, the suction side of the low stage compressor 33 is connected to the second port of the four-way valve 35 via the accumulator 38. The discharge side of the low stage compressor 33 is connected to the suction side of the high stage compressor 34. The discharge side of the high stage compressor 34 is connected to the first port of the four-way valve 35. In this modification, the end of the injection pipe 43 is connected to a pipe connecting the discharge side of the low stage compressor 33 and the suction side of the high stage compressor 34. The medium pressure gas refrigerant flowing through the injection pipe 43 is sucked into the high stage compressor 34 together with the medium pressure refrigerant discharged from the low stage compressor 33.

And the above embodiments are essentially preferred examples and are not intended to limit the present invention, its application, or its scope of use.

As described above, the present invention is useful for a refrigerating device in which gas injection of medium pressure is supplied to a compressor to perform gas injection.

Claims (6)

The compressors 31 and 34, the heat source side heat exchanger 36 and the use side heat exchanger 71 are connected to perform a refrigeration cycle, and the heat source side heat exchanger 36 becomes a condenser and the use side heat exchanger ( A refrigeration apparatus including a cooling operation in which 71 is an evaporator and a refrigerant circuit 20 in which the use-side heat exchanger 71 is a condenser and the heating operation in which the heat source side heat exchanger 36 is an evaporator can be switched. In The refrigerant circuit 20, An injection passage 43 for supplying a medium pressure refrigerant obtained by depressurizing a part of the high pressure liquid refrigerant to the compressors 31 and 34, and an intermediate pressure refrigerant flowing through the injection passage 43 toward the compressors 31 and 34; And a medium pressure heat exchanger (40) for evaporating heat exchange with a high pressure liquid refrigerant, and a gas-liquid separator (51) for separating the medium pressure refrigerant obtained by depressurizing the high pressure liquid refrigerant into a liquid refrigerant and a gas refrigerant. During the cooling operation, the medium pressure gas refrigerant flowing through the injection passage 43 is supplied, and during the heating operation, the medium pressure gas refrigerant flowing out of the gas-liquid separator 51 is supplied to the compressors 31 and 34, respectively. Refrigerating apparatus, characterized in that the path is configured to be changeable. The method according to claim 1, The refrigerant circuit 20 includes a heat source side circuit 30 provided with the compressors 31 and 34 and the heat source side heat exchanger 36 and a use side circuit 70 provided with the use side heat exchanger 71. It is configured by connecting with connecting pipes (21, 22), And the injection passage (43), the intermediate pressure heat exchanger (40), and the gas-liquid separator (51) are installed in the heat source side circuit (30). The method according to claim 1, The gas-liquid separator 51 becomes a downstream side of the heat source side heat exchanger 36 during the cooling operation of the refrigerant circuit 20 and becomes a downstream side of the utilization side heat exchanger 71 during the heating operation. While constituted by a container-shaped member 65 disposed in position, The intermediate pressure heat exchanger 40 is a heat exchange member that is accommodated inside the vessel-shaped member 65 and heat-exchanges the intermediate pressure refrigerant flowing through the injection passage 43 with the liquid refrigerant in the vessel-type member 65 ( 66) Refrigerating apparatus, characterized in that configured by. The method according to claim 1, The supercooling to cool the high pressure liquid refrigerant by heat-exchanging a portion of the high pressure liquid refrigerant with a low pressure refrigerant obtained by depressurizing a part of the high pressure liquid refrigerant to a low pressure at a position on the downstream side of the intermediate pressure heat exchanger 40 during the cooling operation of the refrigerant circuit 20. Refrigerating apparatus, characterized in that the heat exchanger 60 is installed. The method according to claim 1, In the refrigerant circuit 20, a one-stage compression refrigeration cycle is performed, The compressor (31) is characterized in that the medium pressure gas refrigerant flows into the compression chamber during the compression unit. The method according to claim 1, In the refrigerant circuit 20, the low stage compressor 33 and the high stage compressor 34 are connected in series, and a two stage compression refrigeration cycle is performed. The refrigerant circuit (20) is characterized in that the refrigeration apparatus is configured to supply a medium pressure gas refrigerant to the suction side of the high stage compressor (34).

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