JP6735744B2 - Refrigeration cycle equipment - Google Patents

Description

The present invention relates to a refrigeration cycle device that can use on-site piping.

As a conventional refrigeration cycle device that can use on-site piping, for example, a refrigerant that reduces the refrigerant cost by decompressing the refrigerant that flows from the outdoor unit to the on-site liquid piping by a flow control device into a gas-liquid two-phase state A refrigeration system is known (for example, Patent Document 1).

JP, 2012-112622, A

However, in the refrigeration cycle apparatus of Patent Document 1, there is a problem that pressure loss and noise in the liquid pipe become large because the two-phase refrigerant flows in the liquid pipe.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a refrigeration cycle apparatus capable of reducing pressure loss and noise in liquid piping.

A refrigeration cycle apparatus according to the present invention includes a heat source side unit that houses a first compressor, a first heat source side heat exchanger, a first heat source side pressure reducing apparatus, a load side pressure reducing apparatus, and a load side heat source. A first communication pipe that accommodates an exchanger and that is arranged between the first heat source-side pressure reducing device and the load-side pressure reducing device; and between the first compressor and the load-side heat exchanger. A load side unit connected to the heat source side unit via a second communication pipe arranged between the control unit and a load side unit, and the first compressor, the first heat source side heat exchanger, The first heat source-side pressure reducing device, the load-side pressure reducing device, and the load-side heat exchanger are connected via a refrigerant pipe to form a first refrigeration cycle for circulating a first refrigerant, The heat source side unit is arranged between the first heat source side heat exchanger and the first heat source side pressure reducing device, and has a supercooling heat exchanger having a first heat transfer tube and a second heat transfer tube. A first heat source side refrigerant pipe connecting one end of the first heat transfer tube and the first heat source side decompressor, and the other end of the first heat transfer tube and the A second heat-source-side refrigerant pipe connecting the first heat-source-side heat exchanger, a branch connection portion arranged in the first heat-source-side refrigerant pipe, and one end of the second heat transfer pipe. Second heat source side branch refrigerant pipe connecting the first heat source side branch refrigerant pipe , the other one end of the second heat transfer tube, and the intermediate pressure portion of the first compressor And a second heat source side decompression device arranged in the first heat source side branch refrigerant pipe, wherein the subcooling heat exchanger is in a cooling operation in which the load side heat exchanger functions as an evaporator. In which heat is exchanged between the first refrigerant flowing through the first heat transfer tube and the first refrigerant flowing through the second heat transfer tube, and the controller is configured to perform the cooling operation. At this time, the degree of supercooling is increased by adjusting the opening degree of the second heat source-side pressure reducing device, and the temperature of the first refrigerant flowing into the first heat source-side pressure reducing device is adjusted to the first communication. A liquid refrigerant having a pressure lower than the design pressure of the first communication pipe by making the temperature lower than the saturated liquid temperature of the first refrigerant at the design pressure of the pipe and adjusting the opening degree of the first heat source side pressure reducing device. As the above, the first refrigerant is caused to flow into the first communication pipe .
Further, the refrigeration cycle apparatus according to the present invention includes a heat source side unit that houses a first compressor, a first heat source side heat exchanger, and a first heat source side pressure reducing apparatus, a load side pressure reducing apparatus, and a load. A side heat exchanger, a first connecting pipe arranged between the first heat source side pressure reducing device and the load side pressure reducing device, and the first compressor and the load side heat exchanger. And a load side unit that is connected to the heat source side unit via a second communication pipe disposed between the first compressor and the first heat source side heat exchange unit. The reactor, the first heat source-side pressure reducing device, the load-side pressure reducing device, and the load-side heat exchanger are connected via a refrigerant pipe to form a first refrigeration cycle for circulating the first refrigerant. And the heat source side unit is arranged between the first heat source side heat exchanger and the first heat source side decompression device, and has a supercooling heat having a first heat transfer tube and a second heat transfer tube. An exchanger, a first heat-source-side refrigerant pipe connecting the one end of the first heat-transfer tube and the first heat-source-side decompressor, and the other end of the first heat-transfer tube. And a second heat source side refrigerant pipe connecting the first heat source side heat exchanger and a third heat pipe connected between the second communication pipe and one end of the second heat transfer pipe. Further comprising: a heat source side refrigerant pipe; and a fourth heat source side refrigerant pipe connected between the other end of the second heat transfer pipe and the first compressor, the subcooling heat exchanger Is the first refrigerant flowing through the first heat transfer tube and the first refrigerant flowing through the second heat transfer tube during the cooling operation in which the load-side heat exchanger functions as an evaporator. Between the two heat exchangers, the control device adjusts the opening degree of the load side pressure reducing device to increase the degree of supercooling during the cooling operation, and the first heat source side pressure reducing device The temperature of the first refrigerant flowing in is made lower than the saturated liquid temperature of the first refrigerant at the design pressure of the first communication pipe, and the opening degree of the first heat source side pressure reducing device is adjusted. The first refrigerant is caused to flow into the first communication pipe as a liquid refrigerant having a pressure lower than the design pressure of the first communication pipe.

According to the present invention, the opening degree of the first heat source side decompression device is adjusted so that the pressure is less than the design pressure of the first communication pipe, and the first refrigerant is supplied to the first communication pipe. Can be flowed in. Therefore, according to the present invention, since the refrigerant flowing into the first communication pipe can be a liquid refrigerant, it is possible to provide a refrigeration cycle device capable of reducing pressure loss and noise in the first communication pipe. it can.

1 is a schematic refrigerant circuit diagram showing an example of a refrigeration cycle device 1 according to Embodiment 1 of the present invention. It is a control block diagram expressing a part of control in control device 50 of refrigeration cycle device 1 concerning Embodiment 1 of the present invention. 5 is a flowchart showing an example of control processing during a cooling operation in the control device 50 of the refrigeration cycle device 1 according to Embodiment 1 of the present invention. It is a Mollier diagram which shows operation|movement of the refrigerating-cycle apparatus 1 which concerns on Embodiment 1 of this invention. It is a schematic refrigerant circuit diagram which shows an example of the refrigerating cycle device 1 which concerns on Embodiment 2 of this invention. It is a control block diagram expressing a part of control in control device 50 of refrigerating cycle device 1 concerning Embodiment 2 of the present invention. 7 is a flowchart showing an example of control processing during a cooling operation in the control device 50 of the refrigeration cycle device 1 according to Embodiment 2 of the present invention. It is a Mollier diagram which shows operation|movement of the refrigerating-cycle apparatus 1 which concerns on Embodiment 2 of this invention. It is a schematic refrigerant circuit diagram which shows an example of the refrigerating cycle device 1 which concerns on Embodiment 3 of this invention. It is a control block diagram expressing a part of control in control device 50 of refrigerating cycle device 1 concerning Embodiment 3 of the present invention. It is a flow chart which shows an example of control processing at the time of cooling operation in control device 50 of refrigerating cycle device 1 concerning Embodiment 3 of the present invention. It is a Mollier diagram which shows operation|movement of the refrigerating-cycle apparatus 1 which concerns on Embodiment 3 of this invention.

Embodiment 1.
The refrigeration cycle apparatus 1 according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic refrigerant circuit diagram showing an example of the refrigeration cycle device 1 according to the first embodiment. In the following drawings including FIG. 1, the dimensional relationship and shape of each component may be different from the actual one.

As shown in FIG. 1, the refrigeration cycle apparatus 1 includes a heat source side unit 100 (for example, an outdoor unit) and a load side unit 200 (for example, an indoor unit) arranged in parallel with the heat source side unit 100. The heat source side unit 100 and the load side unit 200 are connected by a first connecting pipe 300 (liquid pipe) and a second connecting pipe 400 (gas pipe) which are on-site pipes. Although the refrigeration cycle apparatus 1 of FIG. 1 has a configuration in which one load side unit 200 is connected, it may have a configuration in which a plurality of load side units 200 are connected.

The refrigeration cycle apparatus 1 according to the first embodiment includes a first compressor 2, a first heat source side heat exchanger 3, a first heat source side pressure reducing device 4, a load side pressure reducing device 5, and a load side. A first refrigeration cycle 500 for connecting the heat exchanger 6 via a refrigerant pipe and circulating the first refrigerant is provided. As the first refrigerant circulating in the first refrigeration cycle 500, any kind of refrigerant can be selected according to the application of the refrigeration cycle apparatus 1. For example, in the refrigeration cycle apparatus 1 of Embodiment 1, a natural refrigerant such as CO ₂ or the like, hydrofluorocarbon such as R32 or the like, hydrofluorocarbon such as 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf) or the like. A mixed solvent of olefin and R410A can be used as the first refrigerant.

The first compressor 2 is a variable frequency fluid machine that is housed in the heat source side unit 100, compresses the sucked low-pressure first refrigerant, and discharges the compressed low-pressure first refrigerant as the high-pressure first refrigerant. As the first compressor 2, for example, a scroll compressor whose rotation frequency is controlled by an inverter can be used.

In the first embodiment, the first heat source side heat exchanger 3 is a heat exchanger that functions as a radiator (condenser), and is housed in the heat source side unit 100. In the first embodiment, the first heat source side heat exchanger 3 includes a first refrigerant flowing inside the first heat source side heat exchanger 3 and a heat source side heat exchanger fan (not shown). It is configured to exchange heat with the outside air that is blown (for example, outdoor air). The first heat source side heat exchanger 3 is configured as, for example, a cross-fin type fin-and-tube heat exchanger configured by a heat transfer tube and a plurality of fins.

In the first embodiment, the first heat-source-side decompression device 4 expands and decompresses the high-pressure liquid refrigerant flowing from the first heat-source-side heat exchanger 3, and the first communication pipe 300, which is a field pipe. The first refrigerant having a pressure less than the design pressure is introduced into the first communication pipe 300. For example, the design pressure of the first communication pipe 300 is set to the pressure resistance reference value of the first communication pipe 300. The first heat-source-side pressure reducing device 4 is housed in the heat-source-side unit 100 and is configured as an electronic expansion valve such as a linear electronic expansion valve (LEV) whose opening can be adjusted in multiple stages or continuously.

In the first embodiment, the load-side decompression device 5 further expands and decompresses the first refrigerant having a pressure lower than the design pressure of the first communication pipe 300, which flows from the first communication pipe 300, to reduce the load-side heat. It is made to flow into the exchanger 6. The load-side pressure reducing device 5 is housed in the load-side unit 200, and is configured as an electronic expansion valve such as a linear electronic expansion valve whose opening can be adjusted in multiple stages or continuously.

The load-side heat exchanger 6 is a heat exchanger that functions as an evaporator (cooler) in the first embodiment, and is housed in the load-side unit 200. The load side heat exchanger 6 is configured to exchange heat between the refrigerant flowing inside the load side heat exchanger 6 and the outside air (for example, indoor air), for example. The load-side heat exchanger 6 can be configured as, for example, a cross-fin type fin-and-tube heat exchanger including a heat transfer tube and a plurality of fins. The load-side heat exchanger 6 may be configured so that the outside air is supplied by blowing air from a load-side heat exchanger fan (not shown).

Hereinafter, the operation operation of the refrigeration cycle apparatus 1 in which the load side heat exchanger 6 functions as an evaporator is referred to as “cooling operation”.

The refrigerant pipe which is housed in the heat source side unit 100 and is arranged between the first heat source side decompression device 4 and the first communication pipe 300 has a first connection pipe for connection with the first communication pipe 300. A heat source side connection valve 7a is provided. The heat source side refrigerant pipe, which is housed in the heat source side unit 100 and is arranged between the first compressor 2 and the second communication pipe 400, has a second heat source for connecting to the second communication pipe 400. A side connection valve 7b is provided. The load-side refrigerant pipe accommodated in the load-side unit 200 and arranged between the load-side pressure reducing device 5 and the first communication pipe 300 has a first load-side for connecting with the first communication pipe 300. A connection valve 8a is provided. The load-side refrigerant pipe accommodated in the load-side unit 200 and arranged between the load-side heat exchanger 6 and the second communication pipe 400 has a second load for connecting to the second communication pipe 400. A side connection valve 8b is provided. The first heat source side connection valve 7a, the second heat source side connection valve 7b, the first load side connection valve 8a, and the second load side connection valve 8b are, for example, two-way switches that can be opened and closed. It is composed of a two-way valve such as a solenoid valve.

Next, the subcooling heat exchanger 10 and the second heat source side pressure reducing device 20 in the refrigeration cycle device 1 of the first embodiment will be described.

The subcooling heat exchanger 10 is arranged between the first heat source side heat exchanger 3 and the first heat source side pressure reducing device 4. The subcooling heat exchanger 10 has a first heat transfer tube 10a and a second heat transfer tube 10b, and is housed in the heat source side unit 100. In Embodiment 1, the subcooling heat exchanger 10 includes the high-pressure first refrigerant flowing through the first heat transfer tube 10a and the depressurized first refrigerant flowing through the second heat transfer tube 10b during the cooling operation. It is a heat exchanger that exchanges heat with a refrigerant. The subcooling heat exchanger 10 can be configured as, for example, a cross-fin type fin-and-tube heat exchanger including a first heat transfer tube 10a, a second heat transfer tube 10b, and a plurality of fins.

One end of the first heat transfer tube 10a and the first heat source side pressure reducing device 4 are connected by a first heat source side refrigerant pipe 12. The other end of the first heat transfer tube 10a and the first heat source side heat exchanger 3 are connected by a second heat source side refrigerant pipe 13. The branch connection part 12 a arranged in the first heat source side refrigerant pipe 12 and one end of the second heat transfer pipe 10 b are connected by the first heat source side branch refrigerant pipe 16. The other end of the second heat transfer pipe 10b and the intermediate pressure portion of the first compressor 2 are connected by a second heat source side branch refrigerant pipe 18. The first heat source side refrigerant pipe 12 and the second heat source side refrigerant pipe 13 are a part of the refrigerant pipes that configure the first refrigeration cycle 500. Further, the first heat source side refrigerant pipe 12, the second heat source side refrigerant pipe 13, the first heat source side branch refrigerant pipe 16, and the second heat source side branch refrigerant pipe 18 are housed in the heat source side unit 100. There is.

The second heat source side decompression device 20 is arranged in the first heat source side branch refrigerant pipe 16. The second heat-source-side decompression device 20 expands and decompresses the high-pressure liquid refrigerant that branches and flows from the first heat-source-side refrigerant pipe 12 into the first heat-source-side branch refrigerant pipe 16, and the second heat transfer pipe 10b. It is something that is made to flow into. The second heat-source-side pressure reducing device 20 is housed in the heat-source-side unit 100, and is configured as an electronic expansion valve such as a linear electronic expansion valve (LEV) whose opening can be adjusted in multiple stages or continuously.

Next, the sensor arranged in the refrigeration cycle device 1 according to the first embodiment will be described.

The refrigeration cycle device 1 according to the first embodiment includes a first temperature sensor 30, a second temperature sensor 35, a first pressure sensor 40, and a second pressure sensor 45.

The first temperature sensor 30 is arranged on the first heat source side refrigerant pipe 12 between the branch connection portion 12 a and the first heat source side decompression device 4. The first temperature sensor 30 measures the temperature of the first refrigerant that flows out from the first heat transfer pipe 10a of the subcooling heat exchanger 10 and flows into the first heat source-side decompression device 4 during the cooling operation in the refrigerant pipe. It is a temperature sensor that detects the temperature through.

The second temperature sensor 35 is arranged in the second heat source side branch refrigerant pipe 18. The second temperature sensor 35 is the temperature of the first refrigerant that flows out from the second heat transfer pipe 10b of the subcooling heat exchanger 10 and is injected into the intermediate pressure portion of the first compressor 2 during the cooling operation. Is a temperature sensor for detecting the temperature through a refrigerant pipe.

As a material for the first temperature sensor 30 and the second temperature sensor 35, a semiconductor (for example, a thermistor) or a metal (for example, a resistance temperature detector) is used. The first temperature sensor 30 and the second temperature sensor 35 may be made of the same material or different materials.

The first pressure sensor 40 is arranged in the second heat source side branch refrigerant pipe 18. The first pressure sensor 40 flows out from the second heat transfer pipe 10b of the subcooling heat exchanger 10 during the cooling operation, and the pressure of the first refrigerant injected into the intermediate pressure portion of the first compressor 2 Is a pressure sensor that detects

The second pressure sensor 45 is housed in the load-side unit 200 and is arranged in the load-side refrigerant pipe arranged between the first load-side connecting valve 8 a and the load-side pressure reducing device 5. The second pressure sensor 45 is a pressure sensor that detects the pressure of the first refrigerant flowing into the second pressure sensor 45 through the first communication pipe 300 during the cooling operation.

As the first pressure sensor 40 and the second pressure sensor 45, a crystal piezoelectric pressure sensor, a semiconductor sensor, a pressure transducer, or the like is used. The first pressure sensor 40 and the second pressure sensor 45 may be of the same type or different types.

Next, the control device 50 according to the first embodiment will be described with reference to FIG. FIG. 2 is a control block diagram expressing a part of control in control device 50 of refrigeration cycle device 1 according to the first embodiment.

The control device 50 according to the first embodiment controls the first refrigeration cycle 500 and includes a microcomputer including a CPU, a memory (for example, ROM, RAM, etc.), an I/O port, and the like. ing. As shown in FIG. 2, in the control device 50 according to the first embodiment, the control device 50 includes an electric signal of temperature information detected by the first temperature sensor 30 and the second temperature sensor 35, and a first temperature sensor. The pressure sensor 40 and the second pressure sensor 45 are configured to receive an electric signal of pressure information detected by the pressure sensor 40 and the second pressure sensor 45. The control device 50 transmits a control signal corresponding to the electric signal of the temperature information and the electric signal of the pressure information to the first heat source side pressure reducing device 4, the load side pressure reducing device 5, and the second heat source side pressure reducing device 20. .. In the first heat-source-side pressure reducing device 4, the opening degree of the first heat-source-side pressure reducing device 4 is adjusted according to the transmitted control signal. In the load side pressure reducing device 5, the opening degree of the load side pressure reducing device 5 is adjusted according to the transmitted control signal. In the second heat source-side pressure reducing device 20, the opening degree of the second heat source-side pressure reducing device 20 is adjusted according to the transmitted control signal. Further, the control device 50 can be configured to control the other components of the first refrigeration cycle 500. For example, the control device 50 can be configured to be able to control operating states such as starting and stopping the operation of the heat source side unit 100 and the load side unit 200, and adjusting the operating frequency of the first compressor 2.

The control device 50 is configured to have a storage unit (not shown) capable of storing various data such as the design pressure of the first communication pipe 300. Further, the control device 50 can be configured to have an interface unit (not shown) capable of inputting various data such as the design pressure of the first communication pipe 300.

Next, the operation of the refrigeration cycle device 1 according to the first embodiment during the cooling operation will be described.

The first refrigerant is discharged from the first compressor 2 as a high-temperature and high-pressure gas refrigerant and flows into the first heat source side heat exchanger 3. The high-temperature and high-pressure gas refrigerant that has flowed into the first heat source side heat exchanger 3 is heat-exchanged by releasing heat to a low-temperature medium such as outdoor air, and the first refrigerant becomes a high-pressure liquid refrigerant.

The high-pressure liquid refrigerant flows into the first heat transfer tube 10a of the supercooling heat exchanger 10, is heat-exchanged with the first refrigerant flowing through the second heat transfer tube 10b, and is supercooled. It becomes a supercooled high-pressure liquid refrigerant. In the refrigeration cycle apparatus 1 of the first embodiment, the first refrigerant flowing through the second heat transfer pipe 10b is diverted at the branch connection portion 12a of the first heat source side refrigerant pipe 12 and the first heat source side branch. It is a liquid refrigerant or a two-phase refrigerant that has flowed into the refrigerant pipe 16 and has been expanded and decompressed (for example, at medium pressure) by the second heat source-side pressure reducing device 20. The first refrigerant flowing out from the second heat transfer pipe 10b is injected into the intermediate pressure portion of the first compressor 2 via the second heat source side branch refrigerant pipe 18.

The high-pressure liquid refrigerant supercooled by the supercooling heat exchanger 10 flows into the first heat source-side pressure reducing device 4, is expanded and depressurized by the first heat source-side pressure reducing device 4, and the first refrigerant is It is a reduced pressure (eg, medium pressure) liquid refrigerant or two-phase refrigerant. The depressurized liquid refrigerant or the two-phase refrigerant flows out of the heat source side unit 100 and flows into the load side unit 200 via the first communication pipe 300.

The depressurized liquid refrigerant or two-phase refrigerant that has flowed into the load-side unit 200 flows into the load-side pressure reducing device 5. The depressurized liquid refrigerant or two-phase refrigerant that has flowed into the load-side depressurizer 5 is further expanded and depressurized, and the first refrigerant becomes a low-temperature low-pressure two-phase refrigerant. The low-temperature low-pressure two-phase refrigerant flows into the load-side heat exchanger 6 and absorbs heat from a high-temperature medium such as indoor air, and the first refrigerant evaporates and has a high dryness. It becomes the gas refrigerant. The high-dryness two-phase refrigerant or the low-temperature low-pressure gas refrigerant flowing out from the load side heat exchanger 6 flows out from the load side unit 200 and flows into the heat source side unit 100 via the second communication pipe 400. .. The high-dryness two-phase refrigerant or the low-temperature low-pressure gas refrigerant that has flowed into the load-side unit 200 is sucked into the first compressor 2. The refrigerant sucked into the first compressor 2 is compressed, the first refrigerant becomes a high-temperature high-pressure gas refrigerant, and is discharged from the first compressor 2. The above cycle is repeated in the cooling operation of the refrigeration cycle apparatus 1.

Next, a control process in the control device 50 of the refrigeration cycle device 1 according to the first embodiment will be described.

The control device 50 of the refrigeration cycle device 1 according to the first embodiment adjusts the opening degree of the first heat source side decompression device 4 so that the pressure is less than the design pressure of the first communication pipe 300, and the liquid refrigerant is The first refrigerant is configured to flow into the first communication pipe 300.

Further, the control device 50 of the refrigeration cycle device 1 according to the first embodiment adjusts the opening degree of the second heat source-side pressure reducing device 20 to increase the degree of supercooling during the cooling operation, thereby increasing the first heat source. The temperature of the first refrigerant flowing into the side pressure reducing device 4 can be configured to be lower than the saturated liquid temperature of the first refrigerant at the design pressure.

In the following description of the control process of the first embodiment, it is assumed that the opening degree DH1 of the first heat-source-side decompression device 4 can be adjusted within the range of 0≦DH≦1. The state of the opening degree DH1=0 indicates that the first heat source side pressure reducing device 4 is in the closed state, and the state of the opening degree DH1=1 indicates that the first heat source side pressure reducing device 4 is in the fully open state. Indicates.

In addition, the opening degree DH2 of the second heat source side depressurization device 20 can be adjusted within the range of 0≦DH2≦1. The state of the opening degree DH2=0 indicates that the second heat source side pressure reducing device 20 is in the closed state, and the state of the opening degree DH2=1 indicates that the second heat source side pressure reducing device 20 is in the fully open state. Indicates.

FIG. 3 is a flowchart showing an example of the control process during the cooling operation in the control device 50 of the refrigeration cycle device 1 according to the first embodiment. The control process of FIG. 3 may be performed at all times during the cooling operation, or may be performed at any time, for example, when a variation in the parameters of the refrigeration cycle apparatus 1 such as a frequency variation of the first compressor 2 is detected. Good.

In the first embodiment, it is assumed that the storage unit (not shown) of the control device 50 stores data of the design pressure Pm (for example, pressure resistance reference value) of the first communication pipe 300. In addition, it is assumed that the storage unit of the control device 50 stores, as a table, for example, data relating to the Mollier diagram (P-h diagram) representing the state of the first refrigerant in the refrigeration cycle device 1.

In step S11, the temperature Tc of the first refrigerant flowing into the first heat source-side pressure reducing device 4 detected by the first temperature sensor 30 is equal to or higher than the saturated liquid temperature Ta of the first refrigerant at the design pressure Pm. The control device 50 determines whether or not The saturated liquid temperature Ta is a temperature value calculated by the control device 50 based on the value of the design pressure Pm.

When the temperature Tc of the first refrigerant is equal to or higher than the saturated liquid temperature Ta, in step S12, the control device 50 controls the opening degree DH2 of the second heat-source-side pressure reducing device 20 to open by the adjustment value ΔDH2. Here, the adjustment value ΔDH2 is a constant that is arbitrarily determined in consideration of the specifications such as the structure of the second heat source side depressurization device 20, and for example, the adjustment value ΔDH2 can be 0.02. After that, in the control device 50, the control process of step S12 is repeated until the temperature Tc of the first refrigerant becomes lower than the saturated liquid temperature Ta.

When the temperature Tc of the first refrigerant is lower than the saturated liquid temperature Ta, in step S13, it is determined whether or not the pressure P of the first refrigerant flowing into the load side pressure reducing device 5 is equal to or lower than the saturated liquid pressure Ps. It is determined at 50. Here, the pressure P of the first refrigerant flowing into the load side pressure reducing device 5 is detected by the second pressure sensor 45. The saturated liquid pressure Ps is a pressure value calculated by the control device 50 based on the value of the temperature Tc of the first refrigerant, and on the Mollier diagram, the isoenthalpy change is made from the temperature Tc of the first refrigerant. Shown as dots on the saturated liquid line. When the pressure P of the first refrigerant is higher than the saturated liquid pressure Ps, the control process ends.

When the pressure P of the first refrigerant is equal to or lower than the saturated liquid pressure Ps, in step S14, the control device 50 controls the opening degree DH1 of the first heat-source-side pressure reducing device 4 to open by the adjustment value ΔDH1. Here, the adjustment value ΔDH1 is a constant that is arbitrarily determined in consideration of specifications such as the structure of the first heat-source-side pressure reducing device 4, and the adjustment value ΔDH1 can be 0.01, for example. After that, the control device 50 repeats the control process of step S14 until the pressure P of the first refrigerant becomes higher than the saturated liquid pressure Ps.

Next, the effect of the present invention according to the first embodiment will be described.

As described above, the refrigeration cycle apparatus 1 according to the first embodiment includes the first compressor 2, the first heat source side heat exchanger 3, and the first heat source side depressurization apparatus 4 that accommodate the heat source side. A first communication pipe 300 that accommodates the unit 100, the load-side pressure reducing device 5 and the load-side heat exchanger 6, and is arranged between the first heat source-side pressure reducing device 4 and the load-side pressure reducing device 5, and A load-side unit 200 connected to the heat-source-side unit 100 via a second communication pipe 400 arranged between the first compressor 2 and the load-side heat exchanger 6, and a controller 50. , The first compressor 2, the first heat source side heat exchanger 3, the first heat source side pressure reducing device 4, the load side pressure reducing device 5, and the load side heat exchanger 6 are connected via a refrigerant pipe, The first refrigeration cycle 500 that circulates the first refrigerant is configured, and the control device 50 controls the first heat source side decompression device 4 during the cooling operation in which the load side heat exchanger 6 functions as an evaporator. The opening degree is adjusted so that the first refrigerant flows into the first communication pipe 300 as a liquid refrigerant whose pressure is less than the design pressure of the first communication pipe 300.

As a conventional refrigerating device, for example, a dual refrigerating device, by passing a two-phase refrigerant through a local liquid pipe, the total amount of refrigerant in the refrigerating device is reduced to reduce the refrigerant cost and the product cost. Is generally known. In the conventional refrigeration system, a first expansion valve is provided in the outdoor unit to pass the two-phase refrigerant through the on-site liquid piping, decompresses and expands the refrigerant, and causes the two-phase refrigerant to flow into the on-site liquid piping. .. Further, in the conventional refrigeration system, a second expansion valve is provided in the indoor unit to further decompress and expand the two-phase refrigerant flowing from the on-site liquid pipe, and to make it flow into the indoor heat exchanger functioning as an evaporator. There is. As described above, the conventional refrigeration system has a so-called two-stage throttle structure in which the first expansion valve and the second expansion valve are provided before and after the on-site liquid pipe.

However, in the conventional refrigeration system, since the two-phase refrigerant flows into the local liquid pipe, there is a problem that pressure loss and noise in the local pipe increase. Also, when multiple indoor heat exchangers are installed (for example, when multiple indoor units are installed), the two-phase refrigerant that has flowed in from the local liquid piping is not evenly distributed to the indoor heat exchangers. However, there has been a problem that the distribution of the refrigerant deteriorates as the number of indoor heat exchangers increases.

On the other hand, according to the configuration of the first embodiment, during cooling operation, the opening degree of the first heat source side pressure reducing device 4 is adjusted so that the pressure is less than the design pressure of the first communication pipe 300. As the refrigerant, the first refrigerant can be made to flow into the first communication pipe 300.

In the first embodiment, the refrigerant flowing into the first communication pipe 300 can be a liquid refrigerant, and the pressure loss and noise in the first communication pipe 300 can be reduced, so the refrigeration cycle apparatus 1 Energy consumption can be reduced. Further, since the refrigerant flowing from the first communication pipe 300 into the load side unit 200 is a liquid refrigerant, even if a plurality of load side heat exchangers 6 are installed in the refrigeration cycle device 1, the refrigerant is evenly distributed. Can be distributed to.

In addition, in the first embodiment, the pressure of the liquid refrigerant flowing into the first communication pipe 300 can be set to be less than the design pressure of the first communication pipe 300, so that the existing on-site pipe can be used in the refrigeration cycle apparatus 1 Can be provided. For example, in the first communication pipe 300, the pressure loss of the first refrigerant may occur in a range in which the saturation temperature of the refrigerant in the load side heat exchanger 6 does not fall below the evaporation temperature of the load side heat exchanger 6. It can be diverted.

In addition, in the refrigeration cycle apparatus 1 according to the first embodiment, the heat source side unit 100 is arranged between the first heat source side heat exchanger 3 and the first heat source side decompression device 4, and A subcooling heat exchanger 10 having a heat transfer tube 10a and a second heat transfer tube 10b, and a first heat source side connecting one end of the first heat transfer tube 10a and the first heat source side pressure reducing device 4 Refrigerant pipe 12, second heat source side refrigerant pipe 13 that connects the other end of first heat transfer pipe 10a and first heat source side heat exchanger 3, and first heat source side refrigerant pipe 12 First heat source side branch refrigerant pipe 16 that connects the branch connection portion 12a arranged in the second heat transfer pipe 10b to one end of the second heat transfer pipe 10b, and the other end of the second heat transfer pipe 10b. A second heat source side branch refrigerant pipe 18 that connects the first compressor 2 to the intermediate pressure portion, and a second heat source side decompressor 20 arranged in the first heat source side branch refrigerant pipe 16. The subcooling heat exchanger 10 includes heat exchange between the first refrigerant flowing through the first heat transfer tube 10a and the first refrigerant flowing through the second heat transfer tube 10b during the cooling operation. In the cooling operation, the control device 50 adjusts the opening degree of the second heat source side pressure reducing device 20 to increase the degree of supercooling, and the first heat source side pressure reducing device 4 flows into the first heat source side pressure reducing device 4. The temperature of the refrigerant can be made lower than the saturated liquid temperature of the first refrigerant at the design pressure.

According to the above configuration, the temperature of the first refrigerant flowing into the first heat source-side pressure reducing device 4 can be made lower than the saturated liquid temperature of the first refrigerant at the design pressure, so the first heat source It becomes easy to maintain the first refrigerant in the liquid state even after decompression and expansion by the side decompression device 4.

FIG. 4 is a Mollier diagram showing the operation of the refrigeration cycle apparatus 1 according to the first embodiment. In the Mollier diagram of FIG. 4, the vertical axis represents absolute pressure (MPa) and the horizontal axis represents specific enthalpy (kJ/kg). FIG. 4 shows a saturated liquid line, a saturated vapor line, and each stroke in the first refrigeration cycle 500. For the sake of explanation, the first heat source-side decompression device 4 is provided at a position corresponding to the expansion stroke. Also, the load-side pressure reducing device 5 is schematically shown. Further, in the Mollier diagram of FIG. 4, the broken line is a dashed line, and the refrigerant is decompressed and expanded by the second heat source-side decompression device 20 and heat-exchanged by the second heat transfer tube 10b of the subcooling heat exchanger 10. Shows the state of.

Further, point A on the Mollier diagram of FIG. 4 indicates the position of the saturated liquid temperature Ta of the first refrigerant calculated from the design pressure Pm. Point B on the Mollier diagram in FIG. 4 indicates the position in the condensation process of the first refrigeration cycle 500 that has a constant enthalpy with Point A. Point C on the Mollier diagram in FIG. 4 indicates the position of the temperature Tc of the first refrigerant flowing into the first heat source-side pressure reducing device 4 in the condensing process of the first refrigeration cycle 500. A point D on the Mollier diagram of FIG. 4 is a geometrical enthalpy with respect to the point C, and shows a position in the expansion stroke of the first refrigeration cycle 500 where the pressure becomes the design pressure Pm. Point E on the Mollier diagram of FIG. 4 indicates the intersection of the straight line showing the expansion stroke of the first refrigeration cycle 500 and the saturated liquid line, and the pressure of the first refrigerant is the saturated liquid pressure Ps. Is the position where

According to the above configuration, the opening degree of the second heat source side depressurization device 20 is adjusted so that the first cooling medium flowing through the first heat transfer pipe 10a and the second heat transfer pipe in the subcooling heat exchanger 10 are adjusted. The degree of supercooling can be increased by exchanging heat with the first refrigerant flowing through 10b. That is, according to the above configuration, in the Mollier diagram of FIG. 4, point C can be adjusted so as to be located on the left side of point B. Since the temperature of the first refrigerant at the point B is the same as or slightly higher than the saturated liquid temperature Ta at the point A, when the point C is located on the left side of the point B, the first heat source side decompression device 4 The temperature Tc of the inflowing first refrigerant is always lower than the saturated liquid temperature Ta.

Therefore, according to the above-described configuration, the pressure P of the first refrigerant flowing into the first communication pipe 300 is set higher than the saturated liquid pressure Ps and lower than the design pressure Pm so that the pressure on the first heat source side is reduced. It can be controlled by adjusting the opening of the device 4. In the Mollier diagram of FIG. 4, the state in which the pressure P of the first refrigerant is higher than the saturated liquid pressure Ps and lower than the design pressure Pm is the expansion stroke between points D and E in FIG. Corresponds to position.

Specifically, when the design pressure of the first communication pipe 300 (on-site pipe) is 1.64 MPa, the point A is 38°C, and the condensation temperature is 50°C, the degree of supercooling is about 30°C. The point C is 20°C. Therefore, in order to bring the refrigerant into the liquid state below the design pressure in the first communication pipe 300, the first heat source side pressure reducing device 4 may be controlled to 1.00 MPa to 1.64 MPa.

As described above, according to the configuration of the first embodiment, the temperature Tc of the first refrigerant flowing into the first heat source-side pressure reducing device 4 is set to be lower than the saturated liquid temperature Ta, so that the first heat source side The first refrigerant can maintain the liquid state even after decompression and expansion by the decompression device 4.

Embodiment 2.
The second embodiment of the present invention is a modification of the refrigeration cycle device 1 according to the first embodiment described above. FIG. 5 is a schematic refrigerant circuit diagram showing an example of the refrigeration cycle device 1 according to the second embodiment.

The heat source side unit 100 of the refrigeration cycle apparatus 1 according to the second embodiment includes a second communication pipe 400 instead of the first heat source side branch refrigerant pipe 16 of the refrigeration cycle device 1 according to the first embodiment described above. The third heat source side refrigerant pipe 14 connected to one end of the second heat transfer pipe 10b of the supercooling heat exchanger 10 is provided. Further, the heat source side unit 100 of the refrigeration cycle device 1 of the present Second Embodiment is a subcooling heat exchanger instead of the second heat source side branch refrigerant pipe 18 of the refrigeration cycle device 1 according to the first embodiment described above. A fourth heat source side refrigerant pipe 15 connected between the other end of the second heat transfer tube 10b of 10 and the first compressor 2 is further provided. Further, the heat source side unit 100 of the refrigeration cycle apparatus 1 according to the second embodiment does not have the second heat source side pressure reducing device 20. Further, the second temperature sensor 35 and the first pressure sensor 40 are provided on the fourth heat source side refrigerant pipe 15 in the refrigeration cycle device 1 of the second embodiment. The other structure of the heat source side unit 100 of the refrigeration cycle apparatus 1 according to the second embodiment is the same as that of the refrigeration cycle apparatus 1 according to the first embodiment described above.

FIG. 6 is a control block diagram expressing a part of the control in control device 50 of refrigeration cycle device 1 according to the second embodiment. FIG. 6 is the same as the control block diagram of FIG. 2 except that the second heat-source-side pressure reducing device 20 is not included.

Next, a control process in the control device 50 of the refrigeration cycle device 1 according to the second embodiment will be described.

The control device 50 of the refrigeration cycle device 1 according to the second embodiment adjusts the opening degree of the load side pressure reducing device to increase the degree of supercooling during the cooling operation, so that the first heat source side pressure reducing device is controlled. The temperature of the inflowing first refrigerant is configured to be lower than the saturated liquid temperature of the first refrigerant at the design pressure.

In the following description of the control process of the second embodiment, it is assumed that the opening degree DH1 of the first heat-source-side decompression device 4 can be adjusted within the range of 0≦DH≦1. The state of the opening degree DH1=0 indicates that the first heat source side pressure reducing device 4 is in the closed state, and the state of the opening degree DH1=1 indicates that the first heat source side pressure reducing device 4 is in the fully open state. Indicates.

Further, the opening degree DL of the load side pressure reducing device 5 can be adjusted within the range of 0≦DL≦1. A state of the opening degree DL=0 indicates that the load side pressure reducing device 5 is in the closed state, and a state of the opening degree DL=1 indicates that the load side pressure reducing device 5 is in the fully open state.

FIG. 7 is a flowchart showing an example of the control process during the cooling operation in the control device 50 of the refrigeration cycle device 1 according to the second embodiment. Similar to the control process of FIG. 3, the control process of FIG. 7 may be always performed during the cooling operation. For example, the fluctuation of the parameters of the refrigeration cycle device 1 such as the frequency fluctuation of the first compressor 2 may be changed. It may be performed at any time when it is detected.

Also in the second embodiment, similar to the above-described first embodiment, data of the design pressure Pm (for example, withstand pressure reference value) of the first communication pipe 300 is stored in the storage unit (not shown) of the control device 50. Is stored. In addition, it is assumed that the storage unit of the control device 50 stores, as a table, for example, data relating to the Mollier diagram (P-h diagram) representing the state of the first refrigerant in the refrigeration cycle device 1.

In step S21, the temperature Tc of the first refrigerant flowing into the first heat source-side pressure reducing device 4, which is detected by the first temperature sensor 30, is equal to the design pressure, as in step S11 of the first embodiment. The control device 50 determines whether or not the temperature is equal to or higher than the saturated liquid temperature Ta of the first refrigerant in Pm.

When the temperature Tc of the first refrigerant is equal to or higher than the saturated liquid temperature Ta, in step S22, the control device 50 controls the opening degree DL of the load side pressure reducing device 5 to open by the adjustment value ΔDL. Here, the adjustment value ΔDL is a constant that is arbitrarily determined in consideration of the specifications such as the structure of the load side pressure reducing device 5, and for example, the adjustment value ΔDH2 can be 0.02. After that, in the control device 50, the control process of step S22 is repeated until the temperature Tc of the first refrigerant becomes lower than the saturated liquid temperature Ta.

In step S23, when the temperature Tc of the first refrigerant is lower than the saturated liquid temperature Ta, the pressure P of the first refrigerant flowing into the load side pressure reducing device 5 is similar to step S13 of the first embodiment described above. The control device 50 determines whether or not the saturated liquid pressure is equal to or lower than Ps. When the pressure P of the first refrigerant is higher than the saturated liquid pressure Ps, the control process ends.

In step S24, the controller 50 opens the first heat source side decompression device 4 when the pressure P of the first refrigerant is equal to or lower than the saturated liquid pressure Ps, as in step S14 of the first embodiment. The degree DH1 is controlled to be opened by the adjustment value ΔDH1.

The heat-source-side unit 100 of the refrigeration cycle device 1 of the second embodiment is arranged between the first heat-source-side heat exchanger 3 and the first heat-source-side depressurizing device 4, and includes the first heat transfer tube 10a and the first heat transfer pipe 10a. A subcooling heat exchanger 10 having two heat transfer tubes 10b, a first heat source side refrigerant pipe 12 connecting one end of the first heat transfer tube 10a and the first heat source side pressure reducing device 4, The second heat source side refrigerant pipe 13 that connects the other end of the first heat transfer pipe 10a and the first heat source side heat exchanger 3, the second communication pipe 400, and the second heat transfer pipe 10b. The third heat source side refrigerant pipe 14 connected to one end of the second heat transfer pipe 10b and the fourth compressor connected to the other end of the second heat transfer pipe 10b to the first compressor 2. The subcooling heat exchanger 10 further includes a heat source side refrigerant pipe 15, and the subcooling heat exchanger 10 includes a first refrigerant flowing in the first heat transfer tube 10a and a first refrigerant flowing in the second heat transfer tube 10b during the cooling operation. The heat exchange with the refrigerant is performed, and the control device 50 adjusts the opening degree of the load side pressure reducing device 5 to increase the degree of supercooling during the cooling operation, and the first heat source side pressure reducing device 4 The temperature of the first refrigerant flowing into the cylinder is made lower than the saturated liquid temperature of the first refrigerant at the design pressure.

FIG. 8 is a Mollier diagram showing the operation of the refrigeration cycle device 1 according to the second embodiment. FIG. 8 is the same as the Mollier diagram of FIG. 4 except that the broken line of the alternate long and short dash line showing the state of the refrigerant heat-exchanged in the second heat transfer tube 10b of the subcooling heat exchanger 10 is not shown. is there.

According to the configuration of the second embodiment, the opening degree of the load-side pressure reducing device 5 is adjusted so that the first cooling medium flowing through the first heat transfer pipe 10a and the second cooling medium in the supercooling heat exchanger 10 are adjusted. The degree of supercooling can be increased by exchanging heat with the first refrigerant flowing through the heat pipe 10b. In addition, by setting the temperature Tc of the first refrigerant flowing into the first heat source-side pressure reducing device 4 to be lower than the saturated liquid temperature Ta, the first refrigerant is decompressed and expanded in the first heat source-side pressure reducing device 4 as well. Can maintain a liquid state.

Further, according to the configuration of the second embodiment, since the two-phase refrigerant having a high degree of dryness or the low-temperature low-pressure gas refrigerant flowing out from the load-side heat exchanger 6 is further overheated in the subcooling heat exchanger 10, It is possible to avoid the return of liquid to the compressor 2 of No. 1. Therefore, according to the configuration of the second embodiment, the reliability of the refrigeration cycle device 1 can be improved. Further, according to the configuration of the second embodiment, since all the first refrigerant flowing through the refrigeration cycle device 1 can be used for heat exchange in the load side heat exchanger 6, the cooling capacity of the refrigeration cycle device 1 is reduced. Can be improved.

Embodiment 3.
In the third embodiment of the present invention, the refrigeration cycle apparatus 1 of the first embodiment described above further includes a second refrigeration cycle 600. FIG. 9 is a schematic refrigerant circuit diagram showing an example of the refrigeration cycle device 1 according to the third embodiment.

In the refrigeration cycle apparatus 1 of Embodiment 3, in addition to the configuration of Embodiment 1 described above, the heat source side unit 100 includes a second compressor 62, a second heat source side heat exchanger 63, and a third heat source side heat exchanger 63. The heat source side decompression device 64 and the first heat source side heat exchanger 3 are connected via a refrigerant pipe, and a second refrigeration cycle 600 for circulating the second refrigerant is further provided. The side heat exchanger 3 performs heat exchange between the first refrigerant flowing from the first compressor 2 and the second refrigerant flowing from the third heat source-side pressure reducing device 64 during the cooling operation. The second heat source side heat exchanger functions as a radiator.

The structure and operation of the second compressor 62, the second heat source side heat exchanger 63, and the third heat source side decompression device 64 in the second refrigeration cycle 600 are the same as those of the first compressor 2 and the first heat source. It is the same as the side heat exchanger 3 and the first heat source side pressure reducing device 4. In the third embodiment, as described above, the first heat source side heat exchanger 3 includes the first refrigerant flowing from the first compressor 2 and the third heat source side decompressor during the cooling operation. It functions as a cascade heat exchanger that exchanges heat with the second refrigerant flowing from the device 64.

In the second refrigeration cycle 600 of the third embodiment, for example, hydrofluorocarbons such as R32, hydrofluoroolefins such as 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), R410A and the like. A mixed solvent can be used as the second refrigerant.

FIG. 10 is a control block diagram expressing a part of control in control device 50 of refrigeration cycle device 1 according to the third embodiment. 10 is the same as the control block diagram of FIG. 2 except that the opening degree of the third heat-source-side pressure reducing device 64 is controlled by the control device 50.

FIG. 11 is a flowchart showing an example of the control process during the cooling operation in the control device 50 of the refrigeration cycle device 1 according to the third embodiment. The control process of FIG. 11 is the same as the control process of FIG. 3, and steps S31 to S34 of FIG. 11 correspond to S11 to S14 of FIG. The contents of the other control processing are the same as the control processing of the above-described first embodiment.

FIG. 12 is a Mollier diagram showing the operation of the refrigeration cycle device 1 according to the third embodiment. FIG. 12 is the same as the Mollier diagram of FIG.

Also according to the configuration of the third embodiment, the opening degree of the second heat source side decompression device 20 is adjusted and the supercooling heat exchanger 10 includes the first heat transfer tube 10a as in the first embodiment. It is possible to increase the degree of supercooling by exchanging heat between the first refrigerant flowing through and the first refrigerant flowing through the second heat transfer tube 10b. In addition, by setting the temperature Tc of the first refrigerant flowing into the first heat source-side pressure reducing device 4 to be lower than the saturated liquid temperature Ta, the first refrigerant is decompressed and expanded in the first heat source-side pressure reducing device 4 as well. Can maintain a liquid state.

Further, the configuration of the third embodiment, using CO ₂ as the first refrigerant, for the CO ₂ can be used in the following supercritical state can provide a refrigeration cycle device 1 with excellent safety.

Other embodiments.
Various modifications are possible without being limited to the above-mentioned embodiment. For example, the refrigeration cycle device 1 of the above-described embodiment can be used, for example, in an air conditioner, a refrigerator, or the like.

In addition, when the refrigeration cycle apparatus 1 is used as an air conditioner, it can be configured to perform heating operation. For example, the refrigeration cycle apparatus 1 may be provided with a refrigerant flow switching device (for example, a four-way valve) so that it can switch between cooling operation and heating operation.

In addition, the opening degree of the second heat source side pressure reducing device 20 or the load side pressure reducing device 5 is adjusted using the second temperature sensor 35 and the first pressure sensor 40 in the above-described embodiment to obtain the first It is possible to control so as to suppress the amount of liquid returned to the compressor 2.

Further, the above-described embodiments can be used in combination with each other.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle device, 2 1st compressor, 3 1st heat source side heat exchanger, 4 1st heat source side pressure reducing device, 5 load side pressure reducing device, 6 load side heat exchanger, 7a 1st heat source side Connection valve, 7b second heat source side connection valve, 8a first load side connection valve, 8b second load side connection valve, 10 supercooling heat exchanger, 10a first heat transfer tube, 10b second heat transfer tube , 12 1st heat source side refrigerant piping, 12a branch connection part, 13 2nd heat source side refrigerant piping, 14 3rd heat source side refrigerant piping, 15 4th heat source side refrigerant piping, 16 1st heat source side branch refrigerant Pipe, 18 2nd heat source side branch refrigerant pipe, 20 2nd heat source side decompression device, 30 1st temperature sensor, 35 2nd temperature sensor, 40 1st pressure sensor, 45 2nd pressure sensor, 50 Control device, 62 2nd compressor, 63 3rd heat source side heat exchanger, 64 3rd heat source side decompression device, 100 heat source side unit, 200 load side unit, 300 1st connection piping, 400 2nd Communication pipe, 500 1st refrigeration cycle, 600 2nd refrigeration cycle.

Claims (4)

A heat source side unit that accommodates a first compressor, a first heat source side heat exchanger, and a first heat source side pressure reducing device;
A first communication pipe that houses a load-side pressure reducing device and a load-side heat exchanger, and that is arranged between the first heat-source-side pressure reducing device and the load-side pressure reducing device; and the first compressor. A load side unit connected to the heat source side unit via a second connecting pipe arranged between the load side heat exchanger;
With a control device,
The first compressor, the first heat source side heat exchanger, the first heat source side pressure reducing device, the load side pressure reducing device, and the load side heat exchanger are connected via a refrigerant pipe, 1st refrigerating cycle which circulates the refrigerant of 1 is constituted,
The heat source side unit,
A subcooling heat exchanger that is arranged between the first heat source side heat exchanger and the first heat source side pressure reducing device, and has a first heat transfer tube and a second heat transfer tube;
A first heat source side refrigerant pipe connecting one end of the first heat transfer tube and the first heat source side pressure reducing device;
A second heat source side refrigerant pipe connecting the other end of the first heat transfer tube and the first heat source side heat exchanger;
A first heat source side branch refrigerant pipe connecting the branch connection part arranged in the first heat source side refrigerant pipe and one end of the second heat transfer pipe;
A second heat source side branch refrigerant pipe connecting the other end of the second heat transfer pipe and the intermediate pressure portion of the first compressor;
Further comprising a second heat source side decompression device arranged in the first heat source side branch refrigerant pipe,
The subcooling heat exchanger,
During the cooling operation in which the load-side heat exchanger functions as an evaporator, heat is generated between the first refrigerant flowing through the first heat transfer tube and the first refrigerant flowing through the second heat transfer tube. Exchanges,
The control device is
During the cooling operation,
The degree of supercooling is increased by adjusting the opening degree of the second heat source side pressure reducing device, and the temperature of the first refrigerant flowing into the first heat source side pressure reducing device is determined by designing the first communication pipe. Lower than the saturated liquid temperature of the first refrigerant at pressure,
The opening degree of the first heat source side decompression device is adjusted so that the first refrigerant flows into the first communication pipe as a liquid refrigerant whose pressure is less than the design pressure of the first communication pipe. There is a refrigeration cycle device. A heat source side unit containing a first compressor, a first heat source side heat exchanger, and a first heat source side pressure reducing device;
A first communication pipe that houses a load-side pressure reducing device and a load-side heat exchanger, and that is arranged between the first heat-source-side pressure reducing device and the load-side pressure reducing device; and the first compressor. A load side unit connected to the heat source side unit via a second connecting pipe arranged between the load side heat exchanger;
With a control device,
The first compressor, the first heat source side heat exchanger, the first heat source side pressure reducing device, the load side pressure reducing device, and the load side heat exchanger are connected via a refrigerant pipe, 1st refrigerating cycle which circulates the refrigerant of 1 is constituted,
The heat source side unit,
A subcooling heat exchanger that is arranged between the first heat source side heat exchanger and the first heat source side pressure reducing device, and has a first heat transfer tube and a second heat transfer tube;
A first heat source side refrigerant pipe connecting one end of the first heat transfer tube and the first heat source side pressure reducing device;
A second heat source side refrigerant pipe that connects the other end of the first heat transfer tube and the first heat source side heat exchanger;
A third heat source side refrigerant pipe connected between the second communication pipe and one end of the second heat transfer pipe;
Further comprising a fourth heat source side refrigerant pipe connected between the other end of the second heat transfer tube and the first compressor,
The subcooling heat exchanger,
Between the first refrigerant flowing through the first heat transfer tube and the first refrigerant flowing through the second heat transfer tube during the cooling operation in which the load-side heat exchanger functions as an evaporator. To exchange heat with
The control device is
During the cooling operation,
The opening degree of the load-side pressure reducing device is adjusted to increase the degree of supercooling, and the temperature of the first refrigerant flowing into the first heat source-side pressure reducing device is set to the design pressure of the first communication pipe as described above. Lower than the saturated liquid temperature of the first refrigerant,
The opening degree of the first heat source side decompression device is adjusted so that the first refrigerant flows into the first communication pipe as a liquid refrigerant having a pressure lower than the design pressure of the first communication pipe. There is a refrigeration cycle device. The heat source side unit,
The second compressor, the second heat source side heat exchanger, the third heat source side decompression device, and the first heat source side heat exchanger are connected via a refrigerant pipe to connect the second refrigerant. Second refrigeration cycle to circulate
Is further equipped with,
The first heat source side heat exchanger,
During the cooling operation, heat is exchanged between the first refrigerant flowing from the first compressor and the second refrigerant flowing from the third heat-source-side pressure reducing device,
The second heat source side heat exchanger,
It functions as a radiator during the cooling operation.
The refrigeration cycle apparatus according to claim 1. Refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the first refrigerant is CO _2.

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