WO2007105511A1

WO2007105511A1 - Refrigerating apparatus

Info

Publication number: WO2007105511A1
Application number: PCT/JP2007/054184
Authority: WO
Inventors: Masahiro Yamada; Takahiro Yamaguchi
Original assignee: Daikin Industries, Ltd.
Priority date: 2006-03-06
Filing date: 2007-03-05
Publication date: 2007-09-20
Also published as: JP2007240025A

Abstract

An intermediate pressure heat exchanger (40) and a supercooling heat exchanger (60) are installed in a refrigerant circuit (20). In the refrigerant circuit (20), a first flow passage (61) of the supercooling heat exchanger (60) is disposed on the downstream side, relative to the direction of refrigerant circulation in cooling operation, of the first flow passage (41) of the intermediate pressure heat exchanger (40). In the cooling operation, a high-pressure liquid refrigerant is cooled while it passes through the first flow passage (41) of the intermediate pressure heat exchanger (40) and is supplied to an indoor circuit (70) after it is further cooled while passing through the first flow passage (61) of the supercooling heat exchanger (60).

Description

Refrigeration equipment

Technical field

[0001] The present invention relates to a refrigeration apparatus that performs gas injection by supplying an intermediate-pressure gas refrigerant to a compressor. Background art

Conventionally, a refrigeration apparatus that performs so-called gas injection (that is, an operation of supplying an intermediate-pressure gas refrigerant to a compressor) is known for the purpose of reducing the input to the compressor. For example, FIG. 1 of Patent Document 1 discloses a refrigeration apparatus that performs a single-stage compression refrigeration cycle and that supplies an intermediate-pressure gas refrigerant to a compression chamber in the middle of compression in a compressor. Further, FIG. 13 of Patent Document 1 discloses a refrigeration apparatus that performs a two-stage compression refrigeration cycle, and supplies an intermediate-pressure gas refrigerant between a low-stage compressor and a high-stage compressor! Speak.

[0003] In order to perform gas injection, an intermediate-pressure gas refrigerant must be generated.

Therefore, for example, in the refrigeration apparatus described in FIG. 9 of Patent Document 1, the intermediate-pressure refrigerant is evaporated by exchanging heat with the high-pressure liquid refrigerant in the intermediate-pressure heat exchanger, and the intermediate-pressure refrigerant from the intermediate-pressure heat exchanger to the compressor Supply the gas refrigerant with pressure.

Patent Document 1: JP 2001-033117 A

Disclosure of the invention

Problems to be solved by the invention

[0004] As described above, in the intermediate pressure heat exchange, the high pressure liquid refrigerant dissipates heat to the intermediate pressure refrigerant, so that the degree of supercooling of the high pressure liquid refrigerant is somewhat increased. However, the temperature difference between the intermediate-pressure refrigerant and the high-pressure liquid refrigerant is so large! / Therefore, the increase in the supercooling of the high-pressure liquid refrigerant is not so large. For this reason, the distance to the intermediate pressure heat exchanger force utilization side heat exchanger is long, or the utilization side heat exchanger is provided at a position higher than the intermediate pressure heat exchanger, and the high pressure liquid refrigerant is disposed on the utilization side. If the pressure drops significantly before reaching the heat exchanger, part of the refrigerant may evaporate. For this reason, the amount of liquid refrigerant flowing into the use-side heat exchanger is reduced, which may reduce the cooling capacity obtained by the use-side heat exchanger. [0005] The present invention has been made in view of the strong point, and the object of the present invention is to ensure that the cooling capacity of the refrigeration apparatus that performs so-called gas indication is reliably exhibited regardless of the installation state. .

Means for solving the problem

[0006] In the first invention, the compressor (31, 34), the heat source side heat exchanger (36), and the use side heat exchanger (71) are connected, and the heat source side heat exchanger (36) is condensed. For refrigeration systems equipped with a refrigerant circuit (20) that can perform a cooling operation in which the use-side heat exchanger (71) becomes an evaporator! / The refrigerant circuit (20) includes an injection passage (43) for supplying intermediate pressure refrigerant obtained by decompressing part of the high-pressure liquid refrigerant to the compressor (31, 34), and the injection passage. The intermediate pressure heat exchange (40) for evaporating the intermediate pressure refrigerant (43) flowing toward the compressor (31, 34) by heat exchange with the high pressure liquid refrigerant and the intermediate pressure heat exchange during the cooling operation. ^^ A supercooling heat exchanger that is arranged downstream of (40) and cools the high-pressure liquid refrigerant by heat exchange with the low-pressure refrigerant obtained by reducing the pressure of part of the high-pressure liquid refrigerant to low pressure (60) And are provided.

[0007] In the first invention, the refrigerant circuit (20) can perform at least a cooling operation. During the cooling operation, the refrigerant condensed in the heat source side heat exchanger (36), that is, the high-pressure liquid refrigerant flows into the intermediate pressure heat exchanger (40). In the intermediate pressure heat exchanger (40), the high pressure liquid refrigerant and the intermediate pressure refrigerant flowing through the induction passage (43) exchange heat, and the intermediate pressure refrigerant evaporates to cool the high pressure liquid refrigerant. The intermediate pressure refrigerant evaporated in the intermediate pressure heat exchanger (40) is supplied to the compressor (31, 34). On the other hand, the high-pressure liquid refrigerant cooled by the intermediate pressure heat exchange (40) is sent to the supercooling heat exchanger (60). Supercooling heat exchanger (60) The high-pressure liquid refrigerant that has flowed in is cooled by exchanging heat with the low-pressure refrigerant obtained by decompressing part of the high-pressure liquid refrigerant. The high-pressure liquid refrigerant cooled by the supercooling heat exchange (60) is sent to the use side heat exchange (71). In other words, the high-pressure liquid refrigerant that has flowed out of the heat source side heat exchanger (36) is cooled sequentially by the intermediate pressure heat exchanger (40) and the subcooling heat exchanger (60), and then the use side heat exchanger (71 ).

[0008] In a second aspect based on the first aspect, the refrigerant circuit (20) is a heat source side circuit provided with the compressor (31, 34) and the heat source side heat exchanger (36). (30) and the use side circuit (70) provided with the use side heat exchanger (71) are connected by connecting pipes (21, 22). The injection passage (43), the intermediate pressure heat exchanger (40), and the supercooling heat exchanger (60) are provided in the heat source side circuit (30).

[0009] In the second invention, the refrigerant circuit (20) includes the heat source side circuit (30), the use side circuit (70), and the connecting pipes (21, 22). During the cooling operation, the high-pressure liquid refrigerant cooled when passing through the supercooling heat exchanger (60) flows into the use side heat exchanger (71) through the connecting pipe (21). For this reason, even if the connecting pipe (21, 22) is long or the user circuit (70) is installed at a higher position than the heat source circuit (30), the user heat exchanger (71) The high-pressure refrigerant supplied to is kept in a liquid state, or the amount of high-pressure refrigerant supplied to the use-side heat exchanger (71) is reduced in the middle.

[0010] In a third aspect based on the first aspect, in the refrigerant circuit (20), the use side heat exchanger (71) serves as a condenser and the heat source side heat exchanger (36) evaporates. On the other hand, while the heating operation as a cooler can be switched to the cooling operation, the refrigerant circuit (20) has the supercooling heat exchange from the intermediate pressure heat exchanger (40) in both the cooling operation and the heating operation. A mechanism (50) is provided for switching the refrigerant flow path so that the high-pressure liquid refrigerant flows to the vessel (60).

[0011] In the third invention, the refrigerant circuit (20) can switch between the cooling operation and the heating operation. Although the refrigerant flow path in the refrigerant circuit (20) differs between the cooling operation and the heating operation, the refrigerant passes through the intermediate pressure heat exchanger (40) in both the cooling operation and the heating operation by the operation of the switching mechanism (50). After passing, it flows into the supercooling heat exchanger (60).

The invention's effect

In the refrigerant circuit (20) of the present invention, a supercooling heat exchanger (60) is provided downstream of the intermediate pressure heat exchanger (40) during the cooling operation, and the intermediate pressure heat exchanger (40) The cooled high-pressure liquid refrigerant is introduced into the supercooling heat exchanger (60). The temperature of the low-pressure refrigerant that exchanges heat with the high-pressure liquid refrigerant in the supercooling heat exchanger (60) is lower than the temperature of the intermediate-pressure refrigerant that exchanges heat with the high-pressure refrigerant in the intermediate pressure heat exchanger (40). Therefore, the degree of supercooling of the high-pressure liquid refrigerant supplied to the user-side heat exchanger (71) during the cooling operation is larger than when the high-pressure liquid refrigerant is cooled only by the intermediate pressure heat exchanger (40). It becomes.

[0013] For this reason, the user side heat exchanger (71) is placed at a position far away from Or the user-side heat exchanger (71) is placed at a position higher than the supercooling heat exchanger (60), and the user-side heat exchanger (71) ), Even in an installation situation where the pressure of the high-pressure refrigerant is reduced by force, the high-pressure refrigerant supplied to the user-side heat exchanger (71) can be kept in a liquid state. Of the high-pressure refrigerant supplied to the use-side heat exchanger (71), the amount of vaporization in the middle 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 fully exhibited.

[0014] In the second invention, the refrigerant circuit (20) is constituted by the heat source side circuit (30), the use side circuit (70), and the connection pipes (21, 22). In this case, the heat source side circuit (30) provided with the supercooling heat exchange (60) and the use side circuit (70) provided with the use side heat exchange (71) are located far away from each other. Are often placed at different heights. Therefore, in the refrigeration apparatus (10) including the refrigerant circuit (20) configured as in the present invention, the high-pressure liquid refrigerant cooled by the supercooling heat exchanger (60) during the cooling operation and having a high degree of supercooling. Is supplied to the use side circuit (70), loss due to evaporation of a part of the high-pressure liquid refrigerant before reaching the use side circuit (70) can be reduced. The cooling capacity can be exerted reliably.

[0015] According to the third invention, the intermediate pressure heat exchanger can be used for both the cooling operation and the heating operation!

The refrigerant can flow in the order of (40) to supercooling heat exchange (60).

[0016] Here, the temperature of the low-pressure refrigerant that exchanges heat with the high-pressure liquid refrigerant in the supercooling heat exchanger (60) is higher than the temperature of the intermediate-pressure refrigerant that exchanges heat with the high-pressure refrigerant in the intermediate pressure heat exchanger (40). Lower. For this reason, if the refrigerant flows toward the supercooling heat exchanger (60) force intermediate pressure heat exchanger (40) when the operation is switched, the intermediate pressure heat exchanger (40) The temperature difference between the liquid refrigerant and the intermediate pressure refrigerant is almost eliminated, and there is a possibility that the intermediate pressure gas refrigerant cannot be supplied to the compressor (31, 34). As a countermeasure, it is conceivable to stop the cooling of the high-pressure liquid refrigerant in the supercooling heat exchanger (60), but this makes it impossible to sufficiently increase the degree of supercooling of the high-pressure liquid refrigerant.

[0017] In contrast, in the third aspect of the invention, even when the operation of the refrigerant circuit (20) is switched, the refrigerant flows in the order of intermediate pressure heat exchange (40) to supercooling heat exchange (60). Can do. others Therefore, in both the cooling operation and the heating operation, the intermediate pressure refrigerant supplied to the compressor (31, 34) can be reliably evaporated by the intermediate pressure heat exchanger (40), and at the same time, the supercooling heat exchange can be performed. The high-pressure liquid refrigerant can also be cooled in the vessel (60).

Brief Description of Drawings

圆 1] Piping system diagram showing the configuration of the refrigerant circuit of the air conditioner in Embodiment 1, wherein (A) shows the state during cooling operation, (B) shows the state during heating operation, The

圆 2] Piping system diagram showing the configuration of the refrigerant circuit of the air conditioner in Embodiment 2, wherein (A) shows the state during cooling operation, (B) shows the state during heating operation, The

圆 3] It is a piping system diagram showing a configuration of a refrigerant circuit of an air conditioner in another embodiment.

Explanation of symbols

20 Refrigerant circuit

21 Liquid side connection piping

22 Gas side communication piping

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 Intermediate pressure heat exchange

43 Injection piping (injection passage)

50 bridge circuit (50) (switching mechanism)

70 Indoor circuit (use side circuit)

71 Indoor heat exchange (user side heat exchange)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the present invention will be described. This embodiment is a refrigeration apparatus according to the present invention. Thus, the air conditioner (10) configured.

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) that is a heat source side circuit (30). Each indoor unit (12) accommodates an indoor circuit (70) which is a use side circuit.

[0023] In the air conditioner (10), the refrigerant circuit (20) is formed by connecting the outdoor circuit (30) and the indoor circuit (70) with the liquid side connecting pipe (21) and the gas side connecting pipe (22). Te! In this refrigerant circuit (20), two indoor circuits (70) are connected in parallel to one outdoor circuit (30).

[0024] Each indoor circuit (70) is provided with one indoor heat exchanger (71), which is a use side heat exchanger, and one indoor expansion valve (72). Indoor heat exchange (71) is air heat exchange that exchanges heat between indoor air and 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), the liquid side communication pipe (21) is connected to the end on the indoor expansion valve (72) side, and the gas side communication pipe (22) is connected to the end on the indoor heat exchanger (71) side. Is connected!

[0025] The outdoor circuit (30) includes a compressor (31), a four-way switching valve (35), an outdoor heat exchanger (36) as a heat source side heat exchanger, an outdoor expansion valve (37), An accumulator (38) is provided. The outdoor heat exchanger (36) is provided with an intermediate pressure heat exchanger (40), an injection pipe (43), a supercooling heat exchanger (60), and a supercooling pipe (63). Yes.

[0026] The compressor (31) is a positive displacement 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 in the middle of compression. The compressor (31) has its discharge side connected to the first port of the four-way switching valve (35) and its suction side connected to the second port of the four-way switching valve (35) via the accumulator (38). ing. In the present embodiment, only one compressor (31) is provided in the outdoor circuit (30), but a plurality of compressors may be provided in parallel.

[0027] The outdoor heat exchanger (36) is an air heat exchanger that exchanges heat between outdoor air and the refrigerant. The intermediate pressure heat exchanger (40) and the supercooling heat exchanger (60) are both a double-pipe heat exchanger and a plate type. This is heat exchange that exchanges heat between refrigerants such as heat exchange. A first flow path (41) and a second flow path (42) are formed in the intermediate pressure heat exchange (40). Further, the first flow path (61) and the second flow path (62) are also formed in the supercooling heat exchanger (60).

[0028] The outdoor heat exchanger (36) has one end connected to the third port of the four-way switching valve (35) and the other end connected to the third pressure of the intermediate pressure heat exchanger (40) via the outdoor expansion valve (37). Each is connected to one end of one flow path (41). The other end of the first flow path (41) of the intermediate pressure heat exchanger (40) is connected to one end of the first flow path (61) of the supercooling heat exchanger (60). The other end of the first flow path (61) of the supercooling heat exchanger (60) is connected to the liquid side connecting pipe (21).

[0029] The 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 subcooling heat exchanger (60), and a terminal end connected to the intermediate pressure port (32) of the compressor (31). Has been. The second flow path (42) of the intermediate pressure heat exchanger (40) is arranged in the middle of the injection pipe (43). In the injection pipe (43), an injection expansion valve (44) is provided between the starting end thereof and the second flow path (42) of the intermediate pressure heat exchange (40).

[0030] The supercooling pipe (63) has a start end between the supercooling heat exchanger (60) and the liquid side communication pipe (21), and a terminal end between the accumulator (38) and the four-way switching valve (35). Are connected to each. The second flow path (62) of the supercooling heat exchanger (60) is disposed in the middle of the supercooling pipe (63). In the supercooling pipe (63), a supercooling expansion valve (64) is provided between its starting end and the second flow path (62) of the supercooling heat exchanger (60).

[0031] As described above, the four-way selector valve (35) has a first port on the discharge side of the compressor (31), a second port on the accumulator (38), and a third port on the outdoor heat. Each is connected to the reversal (36). The fourth port of the four-way selector valve (35) is connected to the gas side communication pipe (22). This four-way switching valve (35) has a first state (the state shown in FIG. 1 (A)) 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. Switch to the 2nd state (state shown in Fig. 1 (B)) where the 1 port communicates with the 4th port and the 2nd port communicates with the 3rd port.

[0032] Driving behavior

The air conditioner (10) can be switched between cooling operation and heating operation! [0033] <Cooling operation>

The operation during cooling operation will be described with reference to FIG. 1 (A). In the refrigerant circuit (20) during the cooling operation, the refrigerant circulates so that the outdoor heat exchanger (36) serves as a condenser and the indoor heat exchanger (71) serves as an evaporator. That is, the cooling operation is performed in the refrigerant circuit (20).

Specifically, during the cooling operation, the four-way switching valve (35) is set to the first state. Further, the outdoor expansion valve (37) is set to a fully open state, and the opening degrees of the injection expansion valve (44), the supercooling expansion valve (64), and the indoor expansion valve (72) are adjusted as appropriate.

[0035] The high-pressure gas refrigerant discharged from the compressor (31) is condensed by releasing heat to the outdoor air in the outdoor heat exchanger (36). The high-pressure liquid refrigerant from the outdoor heat exchanger (36) dissipates heat to the refrigerant in the second flow path (42) while passing through the first flow path (41) of the intermediate pressure heat exchanger (40). . The high-pressure liquid refrigerant that also flowed out of the first flow path (41) of the intermediate pressure heat exchanger (40) flows into the partial force S injection pipe (43), and the rest flows into the supercooling heat exchanger (60). To do.

[0036] The high-pressure liquid refrigerant flowing into the injection pipe (43) is reduced to an intermediate pressure when passing through the injection expansion valve (44) to become an intermediate-pressure refrigerant in a 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 exiting 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).

On the other hand, the high-pressure liquid refrigerant flowing into the supercooling heat exchanger (60) radiates heat to the refrigerant in the second flow path (62) while passing through the first flow path (61). Part of the high-pressure liquid refrigerant that has flowed out of the first flow path (61) of the supercooling heat exchanger (60) flows into the supercooling pipe (63), and the rest passes through the liquid side connecting pipe (21). Distributed to each indoor circuit (70). In other words, the high-pressure liquid refrigerant cooled by both the intermediate pressure heat exchanger (40) and the supercooling heat exchanger (60) is supplied to the indoor circuit (70).

[0038] In each indoor circuit (70), the high-pressure liquid refrigerant that has flowed in is reduced in pressure when passing through the indoor expansion valve (72), and then is evaporated by absorbing the indoor aerodynamic force in the indoor heat exchanger (71). The refrigerant evaporated in the indoor heat exchanger (71) returns to the outdoor circuit (30) through the gas side connecting pipe (22), and is sucked into the compressor (31) through the accumulator (38). .

On the other hand, the high-pressure liquid refrigerant flowing into the supercooling pipe (63) passes through the supercooling expansion valve (64). In doing so, the pressure is reduced to a low pressure to become a low-pressure refrigerant in a gas-liquid two-phase state. This low-pressure refrigerant absorbs heat from the refrigerant in the first channel (61) and evaporates while flowing through the second channel (62) of the supercooling heat exchanger (60). The low-pressure gas refrigerant generated in the second flow path (62) of the supercooling heat exchanger (60) returned from the indoor circuit (70) to the outdoor circuit (30) through the gas side connection pipe (22). It is sucked into the compressor (31) together with the low-pressure refrigerant.

[0040] The compressor (31) sucks and compresses the low-pressure refrigerant into the compression chamber through the accumulator (38). In addition, the intermediate pressure gas refrigerant flowing from the intermediate pressure port (32) is introduced into the compression chamber in the middle of compression. The compressor (31) compresses the refrigerant in the compression chamber to a high pressure and discharges it.

[0041] Thus, during the cooling operation, the high-pressure liquid refrigerant that has been cooled when passing through the intermediate pressure heat exchanger (40) and the supercooling heat exchanger (60) and has a high degree of supercooling is It is sent to the indoor circuit (70) through the liquid side connection pipe (21). For this reason, the liquid side communication pipe (21) is longer than a certain length, or the indoor circuit (70) is placed at a position higher than the outdoor circuit (30) to some extent! Even if the degree of supercooling of the liquid refrigerant sent from (30) to the liquid side connecting pipe (21) is small, even if a part of the high-pressure liquid refrigerant evaporates before reaching the indoor circuit (70). The high-pressure refrigerant flowing into the indoor circuit (70) is kept in the liquid single phase state. Even if a part of the high-pressure liquid refrigerant evaporates before reaching the indoor circuit (70), the liquid refrigerant cooled only by the intermediate pressure heat exchanger (40) is transferred from the outdoor circuit (30) to the liquid-side connecting pipe. The amount of high-pressure liquid refrigerant that evaporates is reduced compared to the case of being sent to (21).

[0042] <Heating operation>

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

[0043] Specifically, during the heating operation, the four-way selector valve (35) is set to the second state. Further, the opening degrees of the outdoor expansion valve (37), the indoor expansion valve (72), and the injection expansion valve (44) are adjusted as appropriate, and the supercooling expansion valve (64) is set to a fully closed state.

[0044] The high-pressure gas refrigerant discharged from the compressor (31) is distributed to each indoor circuit (70) through the gas side connecting pipe (22). In the indoor heat exchanger (71) of each indoor circuit (70), the high-pressure gas refrigerant Radiates heat to room air and condenses. In each indoor circuit (70), the refrigerant flowing out of the indoor heat exchanger (71) passes through the indoor expansion valve (72) and then returns to the outdoor circuit (30) through the liquid side communication pipe (21). All of them pass through the first flow path (61) of the supercooling heat exchanger (60). The high-pressure liquid refrigerant that has passed through the supercooling heat exchanger (60) flows into the partial force S injection pipe (43), and the remainder flows into the first flow path (41) of the intermediate pressure heat exchanger (40). To do.

[0045] The high-pressure liquid refrigerant that has flowed into the injection pipe (43) is reduced to an intermediate pressure when passing through the injection expansion valve (44) to become a gas-liquid two-phase intermediate-pressure refrigerant. 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 exiting 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).

On the other hand, the high-pressure liquid refrigerant flowing into the first flow path (41) of the intermediate pressure heat exchanger (40) is cooled by the intermediate pressure refrigerant in the second flow path (42). The high-pressure liquid refrigerant cooled by the intermediate pressure heat exchanger (40) is reduced in pressure when passing through the outdoor expansion valve (37) and flows into the power outdoor heat exchanger (36). 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).

[0047] The compressor (31) sucks the low-pressure refrigerant into the compression chamber through the accumulator (38) and compresses it. In addition, the intermediate pressure gas refrigerant flowing from the intermediate pressure port (32) is introduced into the compression chamber in the middle of compression. The compressor (31) compresses the refrigerant in the compression chamber to a high pressure and discharges it.

[0048] Effect of Embodiment 1

During the cooling operation of the air conditioner (10), the high-pressure liquid refrigerant cooled in each of the intermediate pressure heat exchanger (40) and the supercooling heat exchanger (60) is supplied to the indoor circuit (70). . For this reason, the liquid side connecting pipe (21) connecting the outdoor circuit (30) and the indoor circuit (70) is extremely long, or the indoor circuit (70) is positioned higher than the outdoor circuit (30). Therefore, the high-pressure refrigerant supplied to the indoor circuit (70) is kept in a liquid state even in an installation situation in which the refrigerant pressure greatly decreases while flowing through the liquid side connecting pipe (21). Or the amount of high-pressure refrigerant supplied to the indoor circuit (70) can be reduced. As a result, the amount of liquid refrigerant supplied to the indoor circuit (70) during cooling operation can be secured, and the indoor unit ( The cooling ability of 12) can be fully exerted.

[0049] Here, when a plurality of indoor circuits (70) are connected in parallel to each other as in the air conditioner (10), in order to appropriately adjust the cooling capacity of each indoor unit (12), The refrigerant distribution ratio to the indoor circuit (70) is adjusted by individually controlling the opening of the indoor expansion valve (72) of each indoor circuit (70). However, if the refrigerant passing through the indoor expansion valve (72) enters a gas-liquid two-phase state, the flow characteristics of the indoor expansion valve (72) become unstable, and the distribution ratio of the refrigerant to each indoor circuit (70) becomes appropriate. May be out of control. In contrast, in the air conditioner (10) of the present embodiment, the refrigerant flowing into the indoor circuit (70) during the cooling operation can be easily held in a liquid state. Therefore, according to the present embodiment, in the air conditioner (10) including the plurality of indoor units (12), the cooling capacity of each indoor unit (12) can be accurately controlled.

[Embodiment 2 of the Invention]

Embodiment 2 of the present invention will be described. In this embodiment, a bridge circuit (50) is added to the air conditioner (10) of the first embodiment. Here, the air conditioner (10) of the present embodiment will be described with respect to differences from the first embodiment.

[0051] As shown in FIG. 2, the bridge circuit (50) has four check valves (51 to 54) connected in a bridge shape. This bridge circuit (50) switches the refrigerant circulation path so that the intermediate pressure heat exchanger (40) is located upstream of the supercooling heat exchanger (60) during both cooling and heating operations. And constitutes a shelf structure.

[0052] Each check valve (51 to 54) provided in the bridge circuit (50) is configured to allow only the flow of the refrigerant directed from the inflow side to the outflow side. In this bridge circuit (50), the outflow side of the first check valve (51) is the outflow side of the second check valve (52), and the inflow side of the second check valve (52) is the third check valve ( 53), the inflow side of the third check valve (53) is the inflow side of the fourth check valve (54), and the outflow side of the fourth check valve (54) is the first check valve (51) Are connected to the inflow side.

[0053] In the refrigerant circuit (20) of the present embodiment, the other end of the outdoor heat exchanger (36) is provided between the first check valve (51) and the fourth check valve (54) in the bridge circuit (50). Is connected via the outdoor expansion valve (37), and the liquid side communication pipe (21) is connected between the second check valve (52) and the third check valve (53) in the bridge circuit (50). Yes. In the refrigerant circuit (20), the first circuit in the bridge circuit (50) is used. One end of the first flow path (41) of the intermediate pressure heat exchanger (40) is connected between the check valve (51) and the second check valve (52), and the third check valve in the bridge circuit (50) is connected. The other end of the first flow path (61) of the supercooling heat exchanger (60) is connected between the valve (53) and the fourth check valve (54).

[0054] Driving operation

The operation of the air conditioner (10) of the present embodiment during the cooling operation will be described with respect to differences from the first embodiment.

[0055] As shown in FIG. 2 (A), the refrigerant condensed by the outdoor heat exchange (36) passes through the outdoor expansion valve (37) and the first check valve (51) of the bridge circuit (50). It passes in order, and then flows into the first flow path (41) of the intermediate pressure heat exchanger (40). Subsequently, the refrigerant is cooled while passing through the first flow path (41) of the intermediate pressure heat exchanger (40), and then passes through the first flow path (61) of the supercooling heat exchanger (60). It is further cooled during This point is the same as in the case of the first embodiment. The first flow path (61) force of the supercooling heat exchanger (60) flows out of the refrigerant, passes through the third check valve (53) of the bridge circuit (50), and then passes through the liquid side communication pipe (21). And is distributed to each indoor circuit (70).

[0056] <Heating operation>

The operation during the heating operation of the air conditioner (10) of the present embodiment will be described for the differences from the first embodiment.

[0057] As shown in FIG. 2 (B), the refrigerant condensed in the indoor heat exchanger (71) flows into the outdoor circuit (30) through the liquid side connecting pipe (21). The refrigerant flowing into the outdoor circuit (30) flows into the first flow path (41) of the intermediate pressure heat exchanger (40) through the second check valve (52) of the bridge circuit (50). Cooled while passing through the first flow path (41). Thereafter, the refrigerant flows into the first flow path (61) of the supercooling heat exchanger (60) and is cooled by heat exchange with the low-pressure refrigerant flowing through the second flow path (62). A part of the refrigerant flowing out from the first flow path (61) of the supercooling heat exchanger (60) flows into the supercooling pipe (63), and the rest is the fourth check in the bridge circuit (50). It flows into the outdoor heat exchanger (36) through the valve (54).

[0058] The refrigerant flowing into the supercooling pipe (63) is decompressed to a low pressure when passing through the supercooling expansion valve (64), and becomes a low-pressure refrigerant in a gas-liquid two-phase state. This low-pressure refrigerant absorbs heat from the refrigerant in the first channel (61) and evaporates while flowing through the second channel (62) of the supercooling heat exchanger (60). Excessive The low pressure gas refrigerant that has flowed out of the second flow path (62) of the cooling heat exchanger (60) is returned to the outdoor circuit (30) through the indoor circuit (70) force gas side connecting pipe (22). At the same time, it is sucked into the compressor (31).

[0059] Effect of Embodiment 2

According to the present embodiment, the refrigerant can be flowed in the order of the supercooling heat exchange (60) from the intermediate pressure heat exchanger (40) regardless of whether the cooling operation or the heating operation is performed.

Here, the temperature of the low-pressure refrigerant that exchanges heat with the high-pressure liquid refrigerant in the supercooling heat exchanger (60) is higher than the temperature of the intermediate-pressure refrigerant that exchanges heat with the high-pressure refrigerant in the intermediate pressure heat exchanger (40). Lower. For this reason, if the refrigerant flows from the supercooling heat exchanger (60) to the intermediate pressure heat exchanger (40) during the heating operation, the intermediate pressure heat exchanger (40) can There is almost no difference in temperature of the pressure refrigerant, and there is a risk that the intermediate pressure gas refrigerant cannot be supplied to the compressor (31, 34). As a countermeasure, it is conceivable to stop the cooling of the high-pressure liquid refrigerant in the supercooling heat exchanger (60). However, this makes it impossible to sufficiently increase the degree of supercooling of the high-pressure liquid refrigerant.

In contrast, in the present embodiment, the refrigerant can be flowed in the order of the intermediate pressure heat exchange (40) to the supercooling heat exchange (60) even during the heating operation as well as during the cooling operation. Therefore, in both the cooling operation and the heating operation, the intermediate pressure heat exchanger (40) can reliably evaporate the intermediate pressure refrigerant supplied to the compressor (31, 34), and at the same time, the supercooling heat exchange The high-pressure liquid refrigerant can also be cooled in the vessel (60).

<< Other Embodiments >>

In each of the above embodiments, the low-stage compressor (33) and the high-stage compressor (34) are installed in the outdoor circuit (30), and the refrigerant circuit (20) performs the two-stage compression refrigeration cycle. Also good. Here, the modification applied to the air conditioner (10) of the first embodiment will be described with reference to FIG.

[0063] 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 switching 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) , Connected to the first port of the four-way selector 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 intermediate-pressure gas refrigerant flowing through the injection pipe (43) is drawn into the high-stage compressor (34) together with the intermediate-pressure refrigerant discharged from the low-stage compressor (33).

[0064] The above embodiments are merely preferred examples in nature, and are not intended to limit the scope of the present invention, its application, or its use.

Industrial applicability

[0065] As described above, the present invention is useful for a refrigeration apparatus that performs gas injection by supplying an intermediate-pressure gas refrigerant to a compressor.

Claims

The scope of the claims

[1] The compressor (31, 34), the heat source side heat exchanger (36), and the use side heat exchanger (71) are connected, and the heat source side heat exchanger (36) serves as a condenser and serves as the use side. A refrigeration apparatus comprising a refrigerant circuit (20) capable of performing a cooling operation in which heat exchange (71) serves as an evaporator,

The refrigerant circuit (20)

An injection passage (43) for supplying intermediate pressure refrigerant obtained by decompressing part of the high-pressure liquid refrigerant to the compressor (31, 34);

An intermediate pressure heat exchanger (40) for evaporating the intermediate pressure refrigerant flowing through the injection passage (43) toward the compressor (31, 34) by exchanging heat with the high pressure liquid refrigerant;

The high-pressure liquid refrigerant is cooled by heat exchange with a low-pressure refrigerant that is arranged downstream of the intermediate-pressure heat exchanger (40) during the cooling operation and is obtained by reducing a part of the high-pressure liquid refrigerant to a low pressure. A supercooling heat exchanger (60) is provided.

A refrigeration apparatus characterized by that.

[2] In claim 1,

The refrigerant circuit (20) includes a heat source side circuit (30) provided with the compressor (31, 34) and the heat source side heat exchanger (36) and a use side provided with the use side heat exchanger (71). Side circuit (70) and connecting pipe (21, 22)

The injection passage (43), the intermediate pressure heat exchanger (40), and the supercooling heat exchanger (60) are provided in the heat source side circuit (30).

A refrigeration apparatus characterized by that.

[3] In claim 1,

In the refrigerant circuit (20), the heating operation in which the use side heat exchanger (71) serves as a condenser and the heat source side heat exchanger (36) serves as an evaporator can be switched to the cooling operation. In the refrigerant circuit (20), the flow rate of the refrigerant is such that the high pressure liquid refrigerant flows from the intermediate pressure heat exchanger (40) to the supercooling heat exchanger (60) in both the cooling operation and the heating operation. There is a mechanism (50) for switching the road.

A refrigeration apparatus characterized by that.