Refrigeration device

Abstract

Provided is a refrigeration device that makes it possible to reduce the load of a compressor when filling a refrigerant.　A refrigeration device according to the present disclosure comprises: a refrigeration circuit in which a plurality of compressors including a low-stage compressor and a high-stage compressor, a heat-source-side heat exchanger, a gas-liquid separator, and a plurality of use-side heat exchangers including a first use-side heat exchanger and a second use-side heat exchanger for which the evaporation temperature of the refrigerant is lower than that for the first use-side heat exchanger are connected; and a controller. The first use-side heat exchanger is connected to the high-stage compressor. The second use-side heat exchanger is connected to the high-stage compressor, and has a first service valve in first refrigerant piping that is connected to intermediate-pressure piping between the low-stage compressor and the high-stage compressor. The first service valve has an external connection port for receiving supply of the refrigerant from the outside. The controller is capable of executing, as a refrigerant filling mode, a first refrigerant filling mode, in which the refrigerant supplied from the first service valve is filled into the refrigeration circuit, by operating the high-stage compressor in a state in which the low-stage compressor is stopped.

Description

Refrigeration equipment

[0001] The present disclosure relates to refrigeration devices.

[0002] Patent Document 1 discloses a method of replacing refrigerant through a service valve provided in a low-pressure pipe.

[0003] Patent Document 2 discloses a method for safely replacing a refrigerant in a refrigeration cycle that uses a flammable refrigerant as the operating refrigerant. In this method, after recovering the refrigerant, a service valve is connected to the refrigeration cycle, and the refrigerant is evacuated and recharged via the service valve.

[0004] Japanese Patent Application Publication No. 10-160295

[0005] Japanese Patent Application Publication No. 10-160295

[0006] A first object of the present disclosure is to provide a refrigeration apparatus that can prevent the compressor from running idle when charging a refrigerant.

[0007] A second object of the present disclosure is to provide a refrigeration apparatus to which multiple types of external devices can be easily connected.

[0008] This specification includes the entire contents of Japanese Patent Application No. 2024-014282 filed on February 1, 2024. A refrigeration device of a first aspect that addresses a first problem of the present disclosure includes a refrigeration circuit that connects a plurality of compressors, a heat source side heat exchanger, a gas-liquid separator, and a plurality of user side heat exchangers, and a controller that controls the plurality of compressors, wherein the plurality of compressors include a low stage compressor and a high stage compressor, and the plurality of user side heat exchangers include a first user side heat exchanger and a second user side heat exchanger that has a refrigerant evaporation temperature lower than that of the first user side heat exchanger, and the first user side heat exchanger is connected to the high stage compressor, and The second user-side heat exchanger is connected to the low-stage compressor, and the refrigeration circuit has a first service valve on a first refrigerant pipe connected to a medium-pressure pipe between the low-stage compressor and the high-stage compressor, and the first service valve has an external connection port for receiving a supply of refrigerant from the outside, and the controller is capable of executing a first refrigerant charging mode in which the refrigeration circuit is filled with refrigerant supplied from the first service valve by operating the high-stage compressor with the low-stage compressor stopped as a refrigerant charging mode.

[0009] This specification includes the entire contents of Japanese Patent Application No. 2023-185809, filed on October 30, 2023. A refrigeration device of a second aspect that addresses the second problem of the present disclosure includes a refrigeration circuit connecting multiple compressors, a heat source side heat exchanger, a gas-liquid separator, and a user side heat exchanger, the multiple compressors being configured with a low stage compressor and a high stage compressor, and includes a throttling mechanism between the gas-liquid separator, the heat source side heat exchanger, and the user side heat exchanger, and a first service valve is arranged upstream of the throttling mechanism, and a second service valve is arranged downstream of the throttling mechanism.

[0010] According to the first aspect of the present disclosure, the low-stage compressor is stopped when refrigerant is charged through the first service valve, making it easy to maintain an appropriate pressure difference, thereby preventing the compressor from running idle during refrigerant charging.

[0011] According to the second aspect of the present disclosure, multiple types of external devices can be easily connected.

[0012] 1 is a circuit diagram of a refrigeration device showing operation during cooling operation in embodiment 1. FIG. 2 is a block diagram of the refrigeration device. FIG. 3 is a flowchart showing refrigerant charging setting operation by the refrigeration device. FIG. 4 is a flowchart showing operation of the refrigeration device in a refrigerant charging initial mode and a first refrigerant charging mode. FIG. 5 is a diagram showing a refrigeration circuit of the refrigeration device in the refrigerant charging initial mode. FIG. 6 is a diagram showing a refrigeration circuit of the refrigeration device in the first refrigerant charging mode. FIG. 7 is a flowchart showing operation of the refrigeration device in a second refrigerant charging mode. FIG. 8 is a diagram showing a refrigeration circuit of the refrigeration device in the second refrigerant charging mode. 16 is a circuit diagram of a refrigeration device showing operation during cooling operation in embodiment 3. FIG. 17 is a schematic side view showing a humidity control device (external equipment) in embodiment 3. FIG. 18 is a schematic front view showing a humidity control device (external equipment) in embodiment 3. FIG. 19 is a circuit diagram of a refrigeration device showing operation during heating operation in embodiment 3. FIG. 20 is a circuit diagram of a refrigeration device showing operation during heating operation when the heat absorption by the cooling equipment in embodiment 3 is insufficient. FIG. 21 is a circuit diagram of a refrigeration device showing operation when a large capacity is required in the cooling equipment and a heating heat amount is not required in embodiment 3.

[0013] (Embodiment 1) (Findings and the like that form the basis of the present disclosure) When the inventors first conceived of the refrigeration apparatus of the first aspect of the present disclosure, refrigeration apparatuses had service valves on both the high-pressure and low-pressure pipes that service technicians used when charging refrigerant. However, in a refrigeration apparatus with a two-stage compression configuration, attempting to charge refrigerant through the service valve on the low-pressure pipe required operating both the high-stage and low-stage compressors. This resulted in a problem: when the refrigerant charge amount was large, the pressure in the medium-pressure pipe rose to the same level as the high-pressure pressure, and conversely, when the refrigerant charge amount was small, the pressure dropped to the same level as the low-pressure pressure, resulting in idling and placing a load on the compressor. The present disclosure provides a refrigeration apparatus that can suppress idling of the compressor during refrigerant charging.

[0014] Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters or redundant description of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0015] A first embodiment corresponding to the first aspect of the present disclosure will be described below with reference to FIGS. 1 to 11. [1-1. Configuration] [1-1-1. Configuration of Refrigeration Device] FIG. 1 is a diagram illustrating a refrigeration circuit of a refrigeration device 1 according to the first embodiment. For ease of explanation, in FIG. 1, a valve body in an open state is shown in white, a valve body in a closed state is shown in black, and a throttle mechanism in a closed state is indicated by a dot. For ease of explanation, in FIG. 1, pipes through which a refrigerant flows are shown in bold lines, and pipes through which no refrigerant flows are shown in thin lines. This also applies to subsequent figures. The refrigeration circuit uses a natural refrigerant, carbon dioxide (R744), which is non-flammable and non-toxic. As shown in FIG. 1, the refrigeration device 1 includes an outdoor unit 10, an indoor unit 20, and cooling equipment 30. The indoor unit 20 provides air conditioning for the interior of a store such as a convenience store or supermarket, and the refrigeration equipment 30 provides cooling for the interior of refrigerated showcases and freezer showcases that serve as cooling storage facilities installed within the store.

[0016] The refrigeration system 1 includes an outdoor unit 10 configured by sequentially connecting a two-stage compressor including a low-stage compressor 11 and high-stage compressors 12, 12, a first switching mechanism 50, an outdoor heat exchanger 15, a second switching mechanism 54, and a gas-liquid separator 16. The two high-stage compressors 12, 12 are connected in parallel on the discharge side of the low-stage compressor 11. An accumulator 13 is disposed between the low-stage compressor 11 and the high-stage compressor 12. Refrigerant discharged from the low-stage compressor 11 is separated into gas and liquid by the accumulator 13, and the gas refrigerant is sent to the high-stage compressor 12. An intermediate-pressure pipe 80 is disposed between the discharge port of the low-stage compressor 11 and the suction port of the high-stage compressor 12. The intermediate-pressure pipe 80 connects the discharge port of the low-stage compressor 11 to the accumulator 13.

[0017] An oil separator 14 is connected to the discharge side of the high-stage compressor 12. A first switching mechanism 50 is connected to the oil separator 14, and an outdoor heat exchanger 15 is connected to the first switching mechanism 50. The first switching mechanism 50 includes a pipe 40 connecting the oil separator 14 and the outdoor heat exchanger 15, and a first cooling valve (first on-off valve) 51 is connected to the pipe 40. A first heating pipe 41 is connected to the inlet side of the first cooling valve 51 of the pipe 40. The first heating pipe 41 includes a first heating valve 52 (second on-off valve). The first heating pipe 41 is connected to a pipe 71 connecting the outlet side of the indoor heat exchanger 22 of the indoor unit 20 to the medium-pressure pipe 80. An on-off valve 23 is provided in the pipe 71.

[0018] A first outdoor return pipe 42 is connected to the outlet side of the first cooling valve 51 of the pipe 40. The first outdoor return pipe 42 is equipped with an outdoor refrigerant return valve (third on-off valve) 53. The first outdoor return pipe 42 is connected to a pipe 72 that connects the cooling-use heat exchanger 31 of the cooling equipment 30 to the suction port of the low-stage compressor 11, and this pipe 72 is connected to the cooling-use outlet-side pressure adjustment mechanism 33 of the cooling equipment 30. In this embodiment, the pipe 72 is an example of a "low-pressure pipe."

[0019] A second switching mechanism 54 is connected to the outdoor heat exchanger 15, and the second switching mechanism 54 is connected to the gas-liquid separator 16. The second switching mechanism 54 is formed by annularly connecting the ends of first to fourth pipes 73, 74, 75, and 76 at connectors A, B, C, and D. A second cooling valve (first control valve) 55 and a check valve 59 are disposed in the first pipe 73, a refrigerant return expansion mechanism (second control valve) 58 that controls the flow rate is disposed in the second pipe 74, and a third cooling valve (third control valve) 56 and a check valve 59 are disposed in the third pipe 75. Furthermore, a second heating valve (fourth control valve) 57 and a check valve 59 are disposed in the fourth pipe 76.

[0020] A connection A between the second cooling valve 55 and the refrigerant return expansion mechanism 58 is connected to the outdoor heat exchanger 15, and a connection B between the refrigerant return expansion mechanism 58 and the third cooling valve 56 is connected to a pipe 77 that connects the liquid outlet side of the gas-liquid separator 16 to the cooling heat exchanger 31. The cooling inlet expansion mechanism 32 is connected to this pipe 77. A connection C between the third cooling valve 56 and the second heating valve 57 is connected to the indoor heat exchanger 22 via a pipe (second cooling pipe) 78. The indoor expansion mechanism 21 of the indoor unit 20 is connected to the pipe 78.

[0021] The indoor heat exchanger 22 and the cooling heat exchanger 31 function as so-called use-side heat exchangers. As described above, the indoor heat exchanger 22 is a use-side heat exchanger provided in the indoor unit 20. When the indoor unit 20 performs cooling operation, the indoor heat exchanger 22 functions as an evaporator, and the evaporation temperature thereof is determined by the opening degree of the indoor expansion mechanism 21. In this embodiment, the evaporation temperature of the indoor heat exchanger 22 is determined in accordance with the indoor temperature set in the indoor unit 20. The evaporation temperature range of the indoor heat exchanger 22 is, for example, 3°C to 6°C.

[0022] As described above, the refrigeration heat exchanger 31 is a user-side heat exchanger provided in the refrigeration equipment 30. The refrigeration heat exchanger 31 functions as an evaporator, and the evaporation temperature thereof is determined by the opening degree of the indoor expansion mechanism 21. In the present embodiment, the evaporation temperature of the refrigeration heat exchanger 31 is determined according to the internal temperature set in the refrigeration equipment 30.

[0023] The refrigeration equipment 30 of this embodiment can select and set the temperature range inside the refrigerator from among a refrigeration temperature range (3°C to 6°C), a temperature range slightly higher than the refrigeration temperature range (3°C to 8°C), a partial temperature range (-3°C to -1°C), and a freezing temperature range (-20°C to -18°C). Therefore, the evaporation temperature range of the refrigeration heat exchanger 31 is set lower than the temperature range inside the refrigerator.

[0024] When the refrigeration equipment 30 is set to the refrigeration temperature zone, the evaporation temperature zone of the refrigeration heat exchanger 31 is, for example, −5° C. to 0° C. When the refrigeration equipment 30 is set to the partial temperature zone, the evaporation temperature zone of the refrigeration heat exchanger 31 is, for example, −12° C. to −8° C. When the refrigeration equipment 30 is set to the freezing temperature zone, the evaporation temperature zone of the refrigeration heat exchanger 31 is, for example, −40° C. to −20° C.

[0025] In this way, two use-side heat exchangers with different evaporation temperature ranges are provided in the refrigeration device 1. Of these two use-side heat exchangers 22, 31 with different evaporation temperature ranges, the indoor heat exchanger 22 is connected to the suction side of the high-stage compressor 12, and the cooling heat exchanger 31, which has a lower evaporation temperature range than the indoor heat exchanger 22, is connected to the suction side of the low-stage compressor 11. The indoor heat exchanger 22 corresponds to the "first use-side heat exchanger" in this disclosure, and the cooling heat exchanger 31 corresponds to the "second use-side heat exchanger" in this disclosure.

[0026] A connection D between the second heating valve 57 and the second cooling valve 55 is connected to the gas-liquid separator 16 via a pipe 79. A throttle mechanism 17 is arranged in the pipe 79.

[0027] A gas refrigerant return pipe 60 is connected to the gas outlet side of the gas-liquid separator 16, and the gas refrigerant return pipe 60 is connected to an intermediate pressure pipe 80 and communicates with the accumulator 13 via the intermediate pressure pipe 80. A portion of the gas refrigerant separated in the gas-liquid separator 16 flows into the gas refrigerant return pipe 60. A gas refrigerant flow control valve 61 is connected to the gas refrigerant return pipe 60. The gas refrigerant flow control valve 61 is a valve with an adjustable opening, and opens and closes the gas refrigerant return pipe 60. The gas refrigerant flow control valve 61 blocks the flow of refrigerant in the gas refrigerant return pipe 60 by being fully closed. In the present embodiment, the gas refrigerant return pipe 60 is an example of a "first refrigerant pipe". In the present embodiment, the gas refrigerant flow control valve 61 is an example of a "first opening / closing unit". In the present embodiment, a portion of the gas refrigerant separated in the gas-liquid separator 16 has a flow rate adjusted by the gas refrigerant flow control valve 61, is sent to the accumulator 13, and is returned to the suction side of the high-stage compressor 12.

[0028] In the present embodiment, a first service valve 401 is disposed between the gas refrigerant flow control valve 61 and the accumulator 13. The gas refrigerant flow control valve 61 is located on the gas-liquid separator 16 side of the gas refrigerant return pipe 60 with the first service valve 401 as the reference. In other words, the gas refrigerant flow control valve 61 is located on the opposite side of the gas refrigerant return pipe 60 from the medium-pressure pipe 80 with the first service valve 401 as the reference. Furthermore, a second service valve 402 is disposed in the pipe 72 between the low-stage compressor 11 and the chiller outlet-side pressure adjustment mechanism 33.

[0029] The first service valve 401 has an external connection port 500A to which a refrigerant cylinder can be connected. The first service valve 401 has a first connection port 501A that connects to the gas refrigerant return pipe 60 on the medium-pressure pipe 80 side relative to the external connection port 500A. The first service valve 401 has a second connection port 502A that connects to the gas refrigerant return pipe 60 on the gas-liquid separator 16 side, i.e., the side opposite the medium-pressure pipe 80, relative to the external connection port 500A. In this embodiment, the first connection port 501A is an example of a "second opening / closing part." The second service valve 402 has an external connection port 500B to which a refrigerant cylinder can be connected. The second service valve 402 has a first connection port 501B that connects to the pipe 72 on the low-stage compressor 11 side relative to the external connection port 500B. The second service valve 402 has a second connection port 502B that connects to the refrigerant heat exchanger 31 side relative to the external connection port 500B.

[0030] The first service valve 401 can be switched to a fully open configuration in which all connection ports 500A, 501A, and 502A are open. The first service valve 401 can be switched to an operating configuration in which only the external connection port 500A is closed and the connection ports 501A and 502A are open. The first service valve 401 can be switched to a filling configuration in which only the first connection port 501A is closed and the connection ports 500A and 502A are open. The second service valve 402 can be switched to a fully open configuration in which all connection ports 500B, 501B, and 502B are open. The second service valve 402 can be switched to an operating configuration in which only the external connection port 500B is closed and the connection ports 501B and 502B are open. The second service valve 402 can be switched to a filling mode in which only the first connection port 501B is closed and the connections 500B and 502B are open. This configuration improves the ease of service, such as when replacing the compressor.

[0031] In this embodiment, each of the service valves 401, 402 can be electronically controlled. The mode of each of the service valves 401, 402 is switched among a fully open mode, an operating mode, and a filling mode according to a control signal sent from the controller 700.

[0032] A low-pressure side pressure sensor 601 is arranged in the pipe 72 between the cooling outlet side pressure adjustment mechanism 33 and the second service valve 402 to measure the low pressure. An intermediate-pressure side pressure sensor 602 is arranged in the gas refrigerant return pipe 60 between the intermediate-pressure pipe 80 and the first service valve 401 to measure the intermediate pressure. A high-pressure side pressure sensor 603 is arranged between the high-stage compressor 12 and the oil separator 14 to measure the high-pressure pressure. A second intermediate-pressure side pressure sensor 604 is arranged in the gas refrigerant return pipe 60 to measure the intermediate pressure between the gas-liquid separator 16 and the gas refrigerant flow rate control valve 61.

[0033] The refrigeration system 1 has a controller 700 that stores and executes modes for controlling the refrigeration circuit, and has modes that pattern the valve opening and compressor control during refrigerant charging. The modes include, for example, an initial refrigerant charging mode, a first refrigerant amount adjustment mode, and a second refrigerant amount adjustment mode. The controller 700 determines whether to switch between these modes and has a display means that notifies the user of the determination result. The determination method is, for example, based on the rate of change in pressure. The display means may, for example, include a flashing indicator lamp, an audible alarm to notify the user, a display panel such as a monitor that displays text or images on the screen, or a combination of these.

[0034] The frequency in the compressor control by the controller 700 can be fixed to a frequency specified by the user, or fixed to a frequency automatically determined by the controller 700. The method of automatically determining the frequency estimates the cooling load calculated from the outside air temperature and the set temperatures of the indoor unit 20 and cooling equipment 30 specified by the user, and determines the target amount of refrigerant to be charged and the frequency at which the compressor is to be operated from data relating to the cooling load, refrigerant amount, and frequency obtained in advance.

[0035] 2 is a block diagram of the refrigeration apparatus 1. The controller 700 includes a control unit 701 and a storage unit 703. In this embodiment, the control unit 701 includes a processor such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). In this embodiment, the storage unit 703 includes, for example, a magnetic storage device, a semiconductor storage element, or other types of non-volatile storage device. The storage unit 703 may include a RAM (Random Access Memory) that forms a work area for the control unit 701.

[0036] The storage unit 703 stores mode information 705. The mode information 705 includes information on the valve opening degrees of the valves and information on the operating states of the compressors 11 and 12 when each refrigerant charging mode executed by the controller 700 is executed. Each refrigerant charging mode is executed by the controller 700 when refrigerant is charged into the refrigeration circuit of the refrigeration device 1. The controller 700 can execute an initial refrigerant charging mode, a first refrigerant charging mode, and a second refrigerant charging mode as the refrigerant charging mode.

[0037] The storage unit 703 stores switching information 707. The switching information 707 includes information used to determine whether to switch or terminate each refrigerant charging mode.

[0038] The storage unit 703 stores setting information 709. The setting information 709 includes a set temperature of the refrigeration equipment 30 having the refrigeration heat exchanger 31. The setting information 709 includes information for calculating the operation frequency of the compressors 11, 12 in each refrigerant charging mode. The setting information 709 includes information for calculating a target refrigerant amount, which is a target amount of refrigerant to be charged into the refrigeration circuit of the refrigeration device 1. The setting information 709 includes information for calculating a target high-pressure pressure used when determining that refrigerant charging is complete, from the relationship between the operation frequency and the target refrigerant amount.

[0039] The controller 700 is connected to each device in the outdoor unit 10. The controller 700 is also connected to the indoor unit 20 and the cooling equipment 30 via an outdoor unit I / F 95. The outdoor unit I / F 95 has communication hardware such as a communication interface circuit and a connector for communicating with each device via a cable or the like in accordance with a predetermined communication protocol. The outdoor unit I / F 95 sends data received from each device to the controller 700 and transmits data received from the controller 700 to each device.

[0040] The refrigeration device 1 has a notification unit 801. The notification unit 801 is connected to the controller 700 via the outdoor unit I / F 95. The notification unit 801 notifies the user when each refrigerant charging mode is switched or terminated. In this embodiment, the notification unit 801 includes a display device such as a liquid crystal display panel, an organic EL (Electro Luminescence) panel, or a 7-segment LED (Light Emitting Diode).

[0041] The refrigeration apparatus 1 has an input unit 803. The input unit 803 is connected to the controller 700 via the outdoor unit I / F 95. The input unit 803 includes a switch, a touch panel, or the like that accepts input operations. In this embodiment, the input unit 803 includes a display device that is configured with a liquid crystal display panel, an organic EL panel, a 7-segment LED, or the like, for confirming the accepted input operations.

[0042] [1-2. Operation] The operation of the refrigeration device 1 of this embodiment will be described below. [1-2-1. Refrigerant charging setting operation] Fig. 3 is a flowchart showing the operation of the refrigeration device 1, illustrating the refrigerant charging setting operation. The operation of Fig. 3 is started, for example, when a switch or the like provided on the input unit 803 or the like of the refrigeration device 1 is operated as a trigger.

[0043] In step SA1, the controller 700 estimates the cooling load. The control unit 701 reads the setting information 709 stored in the memory unit 703 and acquires the set temperature of the cooling equipment 30. The control unit 701 also acquires the outside air temperature from an outside air thermometer provided in the refrigeration device 1 or through information communication with the outside. The acquired outside air temperature is a value that is considered to be the outside air temperature at the installation location of the refrigeration device 1 at the time of step SA1. The control unit 701 estimates the cooling load using the acquired set temperature of the refrigeration equipment 30 and the outside air temperature.

[0044] In step SA2, the controller 700 calculates a target refrigerant amount. The control unit 701 reads the setting information 709 stored in the memory unit 703 and acquires data correlating the cooling load with the target refrigerant amount. The control unit 701 calculates the target refrigerant amount using the read data and the cooling load estimated in step SA1.

[0045] In step SA3, controller 700 calculates the target high-pressure pressure. Control unit 701 reads setting information 709 stored in memory unit 703 and acquires data correlating the target refrigerant amount with the target high-pressure pressure. Control unit 701 calculates the target high-pressure pressure using the read data and the target refrigerant amount calculated in step SA2.

[0046] In step SA4, the controller 700 determines whether the frequency setting of each compressor 11, 12 in each refrigerant charging mode is set to the automatic mode. The frequency setting of each compressor 11, 12 in each refrigerant charging mode can be switched between the automatic mode and the manual mode. Switching between the automatic mode and the manual mode is performed, for example, by an input operation via the input unit 803, and a variable corresponding to the switched mode is stored in the memory unit 703. The control unit 701 may determine whether the frequency setting of each compressor 11, 12 in each refrigerant charging mode is the manual mode or the automatic mode, for example, by reading the variable from the memory unit 703. If it is determined that the frequency setting of each compressor 11, 12 in each refrigerant charging mode is the automatic mode (step SA4: YES), the controller 701 proceeds to step SA5. If it is determined that the frequency setting is the manual mode (step SA4: NO), the controller 701 proceeds to step SA7.

[0047] In step SA5, the controller 700 calculates the operating frequency of each compressor 11, 12 when each refrigerant charging mode is being executed. The control unit 701 reads the setting information 709 stored in the memory unit 703 and acquires data correlating the outside air temperature and cooling load with the operating frequency of each compressor 11, 12. The controller 700 calculates the operating frequency of each compressor 11, 12 when each refrigerant charging mode is being executed based on the outside air temperature and cooling load acquired in step SA1.

[0048] In step SA6, the frequency calculated in step SA5 is set as the operating frequency of each compressor 11, 12 during refrigerant charging. In step SA7, the frequency specified by an input operation to input unit 803 is set as the operating frequency of each compressor 11, 12 during refrigerant charging. When step SA6 or step SA7 is completed, the processing in FIG. 3 ends.

[0049] [1-2-2. Operation during refrigerant charging] Next, the operation of the refrigeration device 1 during refrigerant charging in this embodiment will be described. The following operation enables an appropriate amount of refrigerant to be charged in a refrigeration circuit with a two-stage compression configuration, and further allows refrigerant charging to continue even when the amount of gas remaining in the refrigerant cylinder is low.

[0050] First, evacuation before charging the refrigerant is performed by connecting the vacuum pump and the first service valve 401 with a charge hose via a gauge manifold. During evacuation, all valves provided in the refrigeration system 1 are opened. However, the second service valve 402 is in the operating mode, and the external connection port 500B is closed. After evacuation is completed, refrigerant charging begins.

[0051] After evacuation, the external connection port 500A of the first service valve 401 is connected to a refrigerant cylinder filled with the refrigerant to be charged into the circuit via a manifold gauge with a charge hose. When connecting the charge hose, air is purged to prevent air from entering the circuit.

[0052] Fig. 4 is a flowchart showing the operation of the refrigeration apparatus 1, and shows the operation of the refrigeration apparatus 1 in the initial refrigerant charging mode and the first refrigerant charging mode. Fig. 5 is a diagram showing the refrigeration circuit of the refrigeration apparatus 1 in the initial refrigerant charging mode. Fig. 6 is a diagram showing the refrigeration circuit of the refrigeration apparatus 1 in the first refrigerant charging mode. The operation of Fig. 4 is started, for example, when a switch or the like provided on the refrigeration apparatus 1 is operated as a trigger. The operation of the valves in Fig. 4 is included as the initial refrigerant charging mode and the first refrigerant charging mode in mode information 705 stored in the memory unit 703, and is automatically performed by the controller 700.

[0053] In step SB1, the controller 700 executes an operation to switch to the initial refrigerant charging mode. The controller 700 controls the open / close states of the valves provided in the refrigerant circuit of the refrigeration device 1, and divides the refrigerant flow path in the refrigeration circuit into two. Specifically, the controller 700 fully closes the third cooling valve 56, the refrigerant return expansion mechanism 58, the throttling mechanism 17, and the cooling inlet expansion mechanism 32. The first service valve 401 is set to the charging mode. The second service valve 402 is set to the operating mode. Furthermore, the gas refrigerant flow control valve 61 is set to the open state, and its opening degree is set to the maximum.

[0054] In the initial refrigerant charging mode after completion of step SB1, as shown in Fig. 4, the refrigeration circuit of the refrigeration device 1 is divided into two parts, a part including the gas-liquid separator 16 and a part including the low-stage compressor 11 and the high-stage compressor 12, by the closed valves 56, 58, 17, and 32 and the first service valve 401. In the initial refrigerant charging mode, the external connection port 500A of the first service valve 401 communicates with the part including the gas-liquid separator 16 of the two divided flow paths. Therefore, in the initial refrigerant charging mode, refrigerant is charged into the part including the gas-liquid separator 16 of the two divided flow paths of the refrigeration circuit.

[0055] In step SB2, the controller 700 determines whether to switch the mode from the initial refrigerant charging mode to the first refrigerant amount adjustment mode. Specifically, the controller 700 determines whether the rate of change per unit time of the pressure P4 measured by the second intermediate pressure side pressure sensor 604 has fallen below a first rate of change. The first rate of change is included in the switching information 707 stored in the memory unit 703. The first rate of change is an example of the "predetermined rate of change" in the present disclosure.

[0056] After step SB1, as the amount of refrigerant charged into the refrigeration circuit increases, the pressure P4 in the refrigeration circuit increases and the internal pressure of the refrigerant cylinder decreases. Therefore, as the amount of refrigerant charged into the refrigeration circuit increases, the refrigerant charging speed decreases and the rate of change of the pressure P4 per unit time decreases. That is, in step SB2, it is determined whether the internal pressure of the refrigerant cylinder and the pressure on the refrigeration circuit side have reached equilibrium and further refrigerant charging is no longer possible, based on the rate of change of the pressure P4 per unit time.

[0057] If the time rate of change of the pressure P4 is equal to or greater than the first rate of change (step SB2: NO), the determination of step SB2 is repeated. If the time rate of change of the pressure P4 is lower than the first rate of change, the process proceeds to step SB3. When the process proceeds from step SB2 to step SB3, the refrigerant charging initial mode ends.

[0058] In step SB3, the controller 700 controls the open / close states of the valves to connect the two separated refrigeration circuit paths. Specifically, the controller 700 opens the indoor expansion mechanism 21, the on-off valve 23, the cooling inlet expansion mechanism 32, the first cooling valve 51, the second cooling valve 55, and the third cooling valve 56. The controller 700 also closes the first heating valve 52, the outdoor refrigerant return valve 53, the second heating valve 57, the refrigerant return expansion mechanism 58, and the gas refrigerant flow control valve 61. The controller 700 sets the second service valve 402 to an operating state. The controller 700 sets the first service valve 401 to a fully open state. As shown in FIG. 6 , the open / close states of these valves are the same as those during cooling operation, except that the gas refrigerant flow control valve 61 is fully closed and the first service valve 401 is fully open. The information on the opening degree of each valve in step SB3 is included as a first refrigerant charging mode in the mode information 705, and is performed automatically by the controller 700. By opening and closing this gas refrigerant flow control valve 61, it is possible to provide a method that is different from the refrigerant charging initial mode, even when refrigerant is charged from the same first service valve 401.

[0059] In step SB4, the controller 700 starts the operation of the two high-stage compressors 12. At this time, the operation frequency of the high-stage compressors 12 is fixed to the frequency calculated in step SA5 of Fig. 3 in the automatic mode. In the manual mode, the operation frequency of the high-stage compressors 12 is fixed to the frequency specified by the input operation received by the input unit 803.

[0060] The operations of steps SB3 and SB4 switch the operation of the refrigeration system 1 to a first refrigerant charging mode. In the first refrigerant charging mode, refrigerant is charged by using a single-stage compression in which only the high-stage compressor 12 is operated, lowering the intermediate pressure in the refrigerant pipe connected to the first service valve 401, and creating a pressure difference between the pressure in the refrigerant cylinder and the intermediate pressure.

[0061] 6, in the first refrigerant charging mode, the refrigerant charged from the external connection port 500A of the first service valve 401 flows through the gas refrigerant return pipe 60 to the medium-pressure pipe 80, the accumulator 13, and the high-stage compressor 12. As described above, in the gas refrigerant return pipe 60, the gas refrigerant flow control valve 61 located closer to the gas-liquid separator 16 than the first service valve 401 is closed. For this reason, the pressure in the gas refrigerant return pipe 60 can be reduced by operating the high-stage compressor 12.

[0062] In step SB5, controller 700 determines whether to switch the mode from the first refrigerant amount adjustment mode to the second refrigerant amount adjustment mode. Specifically, controller 700 determines whether the rate of change per hour of high-pressure pressure P3 measured by high-pressure-side pressure sensor 603 has fallen below a second rate of change. The second rate of change is included in switching information 707 stored in memory 703. In step SB5, similar to step SB2, controller 700 determines whether the internal pressure of the refrigerant cylinder and the pressure on the refrigeration circuit side have reached equilibrium and further refrigerant charging is no longer possible, based on the rate of change per hour of high-pressure pressure P3. The second rate of change is an example of the "predetermined rate of change" in the present disclosure.

[0063] In step SB5, if the rate of change of the high-pressure P3 per unit time is equal to or greater than the second rate of change (step SB5: NO), the determination in step SB5 is repeated. If the rate of change of the high-pressure P3 per unit time is lower than the second rate of change (step SB5: YES), the process proceeds to step SB6.

[0064] In step SB6, the controller 700 ends the first refrigerant charging mode. Specifically, the controller 700 stops the high-stage compressor 12. The controller 700 switches the first service valve 401 to the operating mode and closes the external connection port 500A. This closes the refrigeration circuit of the refrigeration device 1 to the outside.

[0065] In step SB7, controller 700 causes notification unit 801 to execute a notification. The notification by notification unit 801 in step SB7 includes an instruction to reconnect the charge hose connected to first service valve 401 to connection port 500B of second service valve 402. Execution of step SB7 completes a series of operations from the start of the initial refrigerant charging mode to the end of the first refrigerant charging mode.

[0066] After the series of operations shown in FIG. 4 is completed, the charge hose of the refrigerant cylinder is reconnected from the first service valve 401 to the second service valve 402 by a service technician following the instructions shown in the notice.

[0067] Fig. 7 is a flowchart showing the operation of the refrigeration device 1 in the second refrigerant charging mode. Fig. 8 is a diagram showing the refrigeration circuit of the refrigeration device 1 in the second refrigerant charging mode. The operation of Fig. 7 is triggered by the operation of a predetermined switch or the like after step SB7.

[0068] In step SC1, the controller 700 opens and closes each valve of the refrigeration apparatus 1. The controller 700 switches the second service valve 402 to a fully open state. Furthermore, the controller 700 sets each valve of the refrigeration apparatus 1, except for the second service valve 402, to the same open / close states as during cooling operation. Specifically, the controller 700 opens the indoor expansion mechanism 21, the on-off valve 23, the cooling inlet expansion mechanism 32, the first cooling valve 51, the second cooling valve 55, the third cooling valve 56, and the gas refrigerant flow control valve 61. More specifically, the controller 700 fully opens the gas refrigerant flow control valve 61. Furthermore, the controller 700 closes the first heating valve 52, the outdoor refrigerant return valve 53, the second heating valve 57, and the refrigerant return expansion mechanism 58. The controller 700 sets the first service valve 401 to an operating state. The operation of each valve in step SC1 is included as the second refrigerant charging mode in the mode information 705 stored in the storage unit 703, and is automatically executed by the controller 700.

[0069] In step SC2, the controller 700 starts the operation of the low-stage compressor 11 and the high-stage compressor 12. At this time, in the automatic mode, the operation frequencies of the compressors 11 and 12 are fixed to the frequencies calculated in step SA5 of Fig. 3. In the manual mode, the operation frequencies of the compressors 11 and 12 are fixed to the frequencies specified by the input operation received by the input unit 803.

[0070] By executing steps SC1 and SC2, the operation of the refrigeration system 1 switches to the second refrigerant charging mode. In the second refrigerant charging mode, the refrigeration system 1 performs two-stage compression and charges the refrigerant by lowering the low-pressure in the refrigerant pipe connected to the second service valve 402 to create a pressure difference between the pressure in the refrigerant cylinder and the intermediate pressure. This makes it possible to charge the refrigerant even when the amount of gas remaining in the refrigerant cylinder is low.

[0071] In step SC3, the controller 700 determines whether the target refrigerant amount has been filled into the circuit. For this determination, for example, the value of the high-pressure pressure P3 measured by the high-pressure-side pressure sensor 603 is used in relation to the target high-pressure pressure for the target refrigerant amount and the operating frequency. That is, if the high-pressure pressure P3 is equal to or greater than the target high-pressure pressure, it is determined that the target refrigerant amount has been filled into the circuit.

[0072] If it is determined that the target refrigerant amount has been filled into the circuit (step SC3: YES), the process proceeds to step SC4. If it is determined that the target refrigerant amount has not been filled into the circuit (step SC3: NO), step SC3 is repeated.

[0073] In step SC4, the controller 700 ends the second refrigerant charging mode. The controller 700 stops the high-stage compressor 12 and the low-stage compressor 11. The controller 700 switches the second service valve 402 to the operating mode and closes the external connection port 500B. This closes the refrigerant circuit of the refrigeration device 1 to the outside.

[0074] In step SC5, the controller 700 causes the notification unit 801 to execute a notification. The notification by the notification unit 801 in step SC5 includes information that the second refrigerant charging mode has been completed. By executing step SC5, the series of operations of the refrigeration device 1 during refrigerant charging is completed.

[0075] [1-2-3. Operation During Operation] Next, the operation during operation of this embodiment will be described. During the following operation, the service valves 401 and 402 are in the operating mode, and the external connection ports 500A and 500B are closed. First, the operation during cooling operation will be described. During cooling operation, as shown in FIG. 1 , the outdoor heat exchanger 15 is used as a gas cooler or radiator, and the indoor heat exchanger 22 and the cooling heat exchanger 31 are used as evaporators. When performing cooling operation, the first switching mechanism 50 opens the first cooling valve 51 and closes the remaining first heating valve 52 and outdoor refrigerant return valve 53. Furthermore, the second switching mechanism 54 opens the second cooling valve 55 and the third cooling valve 56 and closes the second heating valve 57 and the refrigerant return expansion mechanism 58. In this state, by driving the low-stage compressor 11 and each high-stage compressor 12, the refrigerant compressed by the low-stage compressor 11 is sent to each high-stage compressor 12, where it is further compressed and discharged toward the oil separator 14.

[0076] The refrigerant that has passed through the oil separator 14 is sent to the outdoor heat exchanger 15 through the first cooling valve 51 of the first switching mechanism 50, where it exchanges heat with outdoor air. After heat exchange, the refrigerant is sent from connection A of the second switching mechanism 54 to the gas-liquid separator 16 via the second cooling valve 55. The refrigerant separated in the gas-liquid separator 16 passes through piping 77 to connection B of the second switching mechanism 54. One of the refrigerants branched at connection B is sent to the indoor heat exchanger 22 via the third cooling valve 56 and the indoor expansion mechanism 21 of the indoor unit 20. In the indoor heat exchanger 22, the refrigerant exchanges heat with indoor air to cool it. The refrigerant that has exchanged heat with the indoor air passes through piping 71, the on-off valve 23, the intermediate-pressure piping 80, and the accumulator 13, and is returned to the suction side of each high-stage compressor 12.

[0077] The other refrigerant branched at connection point B is sent to the refrigeration heat exchanger 31 via the refrigeration inlet expansion mechanism 32 of the refrigeration equipment 30, where it undergoes heat exchange and cools the refrigeration equipment 30. The refrigerant that has undergone heat exchange in the refrigeration heat exchanger 31 is returned to the low-stage compressor 11 via the refrigeration outlet pressure adjustment mechanism 33.

[0078] Next, the operation of the first heating operation (heating operation) will be described. FIG. 9 is a circuit diagram of the refrigeration system 1 showing the heating operation. The flow of refrigerant is indicated by arrows in the figure. The first heating operation is performed using the indoor heat exchanger 22 as a gas cooler or radiator and the cooling heat exchanger 31 as an evaporator. As shown in FIG. 9, when performing the heating operation, the first switching mechanism 50 opens the first heating valve 52 and closes the remaining first cooling valve 51 and outdoor refrigerant return valve 53. The second switching mechanism 54 opens the second heating valve 57 and closes the second cooling valve 55, the third cooling valve 56, and the refrigerant return expansion mechanism 58.

[0079] In this state, by driving the low-stage compressor 11 and each high-stage compressor 12, the refrigerant compressed by the low-stage compressor 11 is sent to each high-stage compressor 12, where it is further compressed and discharged toward the oil separator 14. The refrigerant that has passed through the oil separator 14 passes through the first heating valve 52 of the first switching mechanism 50 and is sent to the indoor heat exchanger 22, where it exchanges heat with the indoor air and heats the indoor air.

[0080] The refrigerant that has exchanged heat in the indoor heat exchanger 22 passes through the indoor expansion mechanism 21, reaches the connection point C of the second switching mechanism 54, and is sent to the gas-liquid separator 16 via the second heating valve 57. The refrigerant separated in the gas-liquid separator 16 passes through piping 77, reaches the connection point B of the second switching mechanism 54, and is sent to the chiller-unit heat exchanger 31 via the chiller-unit inlet-side expansion mechanism 32. This refrigerant undergoes heat exchange in the chiller-unit heat exchanger 31 and cools the chiller-unit equipment 30. The refrigerant that has exchanged heat in the chiller-unit heat exchanger 31 passes through piping 72 and is returned to the suction side of the low-stage compressor 11 via the chiller-unit outlet-side pressure adjustment mechanism 33. In the refrigeration system 1 of the present disclosure, during the first heating operation, the indoor heat exchanger 22 functions as a gas cooler or a radiator, and the outdoor heat exchanger 15 is not used.

[0081] Next, we will explain the operation of the second heating operation at full capacity when the heat output from the cooling equipment 30 is insufficient, for example, when the outdoor temperature is lower than the temperature inside the cooling equipment 30. FIG. 10 is a circuit diagram of the refrigeration system 1 illustrating the heating operation when the heat output from the cooling equipment 30 is insufficient. The refrigerant flow is indicated by arrows in the figure. The second heating operation is performed using the indoor heat exchanger 22 as a gas cooler or radiator, and the cooling heat exchanger 31 and the outdoor heat exchanger 15 as evaporators. When performing the second heating operation at full capacity, the first switching mechanism 50 opens the first heating valve 52 and the outdoor refrigerant return valve 53 and closes the first cooling valve 51. The second switching mechanism 54 opens the second heating valve 57 and the refrigerant return expansion mechanism 58 and closes the second cooling valve 55 and the third cooling valve 56.

[0082] In this state, by driving the low-stage compressor 11 and each high-stage compressor 12, the refrigerant compressed by the low-stage compressor 11 is sent to each high-stage compressor 12, where it is further compressed and discharged toward the oil separator 14. The refrigerant that has passed through the oil separator 14 is sent to the indoor heat exchanger 22 through the first heating valve 52 of the first switching mechanism 50, where it exchanges heat with the indoor air and heats the indoor air.

[0083] The refrigerant that has exchanged heat in the indoor heat exchanger 22 is sent to the gas-liquid separator 16 via the second heating valve 57 of the second switching mechanism 54. The refrigerant separated in the gas-liquid separator 16 reaches the connection B of the second switching mechanism 54 through piping 77. One of the refrigerants branched at connection B passes through the refrigerant return expansion mechanism 58 of the second switching mechanism 54 and connection A, and is sent to the outdoor heat exchanger 15, where it exchanges heat with outside air. The other refrigerant branched at connection B is sent to the chilled-unit heat exchanger 31 via the chilled-unit inlet expansion mechanism 32, where it exchanges heat and cools the chilled-unit equipment 30. The refrigerant that has exchanged heat in the chilled-unit heat exchanger 31 and the refrigerant that has exchanged heat in the outdoor heat exchanger 15 and is sent from the first outdoor return piping 42 are joined at piping 72 and returned to the suction side of the low-stage compressor 11.

[0084] The refrigerant that has exchanged heat in the refrigeration heat exchanger 31 is adjusted by the refrigeration outlet pressure adjustment mechanism 33 so that its pressure is the same as that of the refrigerant sent from the first outdoor return pipe 42. This is the operation when the outside air temperature is lower than the temperature inside the refrigeration equipment 30.

[0085] This allows the exhaust heat from the refrigeration heat exchanger 31 and the heat pumped up by the outdoor heat exchanger 15 to be used as heat for the indoor heat exchanger 22, thereby increasing the heating capacity when the amount of heat exhausted to the refrigeration equipment 30 is insufficient.

[0086] In this case, if the outside air temperature becomes lower than the temperature inside the refrigerator 30, heat cannot be pumped from the outdoor heat exchanger 15 unless the evaporation temperature of the refrigerator 30 is lowered. Lowering the evaporation temperature of the refrigerator 30 will result in a temperature lower than the specified temperature, shortening the thermocycle, resulting in short-cycle operation and possibly causing frozen products. In this embodiment, the above-mentioned problems can be avoided by controlling the opening of the refrigerator outlet pressure adjustment mechanism 33 to balance the pressure with the refrigerant sent from the outdoor heat exchanger 15.

[0087] Next, an operation when a large capacity of the cooling equipment 30 is required but a large amount of heat is not required for heating will be described. FIG. 11 is a circuit diagram of the refrigeration system 1 illustrating the operation when a large amount of heat is not required for heating. The flow of refrigerant is indicated by arrows in the figure. As shown in FIG. 11 , the third heating operation is performed using the outdoor heat exchanger 15 and the indoor heat exchanger 22 as gas coolers or radiators, and the cooling heat exchanger 31 as an evaporator. When performing the third heating operation, the first switching mechanism 50 opens the first cooling valve 51 and the first heating valve 52 and closes the outdoor refrigerant return valve 53. The second switching mechanism 54 opens the second cooling valve 55 and the second heating valve 57 and closes the third cooling valve 56 and the refrigerant return expansion mechanism 58.

[0088] In this state, by driving the low-stage compressor 11 and each high-stage compressor 12, the refrigerant compressed by the low-stage compressor 11 is sent to each high-stage compressor 12, where it is further compressed and discharged toward the oil separator 14.

[0089] The refrigerant that has passed through the oil separator 14 is sent to the outdoor heat exchanger 15 through the first cooling valve 51 of the first switching mechanism 50, and at the same time, is sent to the indoor heat exchanger 22 through the first heating valve 52. The outdoor heat exchanger 15 and the indoor heat exchanger 22 function as a gas cooler or a radiator, exchanging heat with outdoor air in the outdoor heat exchanger 15 and with indoor air in the indoor heat exchanger 22, thereby heating the indoor air. The refrigerant that has exchanged heat in the outdoor heat exchanger 15 reaches the second cooling valve 55 from the connection part A of the second switching mechanism 54, and the refrigerant that has exchanged heat in the indoor heat exchanger 22 reaches the second heating valve 57 from the connection part C of the second switching mechanism 54, where they join and are sent to the gas-liquid separator 16. The refrigerant separated in the gas-liquid separator 16 is sent through a pipe 77 to the chilled heat exchanger 31, where it undergoes heat exchange and cools the chilled equipment 30. The refrigerant that has exchanged heat in the chilled heat exchanger 31 is returned to the suction side of the low-stage compressor 11 via the chilled outlet pressure adjustment mechanism 33.

[0090] According to this, during heating operation, the exhaust heat from the cooling equipment 30 can be dissipated by the outdoor heat exchanger 15 and the indoor heat exchanger 22, thereby increasing the cooling capacity of the cooling equipment 30 and removing frost that has adhered to the outdoor heat exchanger 15.

[0091] The refrigeration device 1 is equipped with a first service valve 401 on the piping connecting the accumulator 13 and the gas refrigerant flow control valve 61, a second service valve 402 on the piping connecting the suction port of the low-stage compressor 11 and the cooling outlet side pressure adjustment mechanism 33, a controller 700 that controls the valve opening and compressor frequency, and a mode that patterns the valve opening during refrigerant charging, and can charge the refrigeration device 1 with an appropriate amount of refrigerant while preventing overload on the compressor, charging refrigerant when the amount of remaining gas in the refrigerant cylinder is low, and reducing the number of service valves.

[0092] [1-3. Effects, etc.] As described above, in this embodiment, the refrigeration device 1 includes a refrigeration circuit connecting a plurality of compressors 11, 12, an outdoor heat exchanger 15, a gas-liquid separator 16, and a plurality of use-side heat exchangers 22, 31, and a controller 700 that controls the plurality of compressors 11, 12. The plurality of compressors 11, 12 include a low-stage compressor 11 and a high-stage compressor 12. The plurality of use-side heat exchangers 22, 31 include an indoor heat exchanger 22 and a cold-setting heat exchanger 31 having a refrigerant evaporation temperature lower than that of the indoor heat exchanger 22. The indoor heat exchanger 22 is connected to the high-stage compressor 12, and The refrigeration system is characterized in that the refrigeration circuit has a first service valve 401 in a gas refrigerant return pipe 60 connected to an intermediate-pressure pipe 80 between the low-stage compressor 11 and the high-stage compressor 12, the first service valve 401 having an external connection port 500A for receiving a supply of refrigerant from an external source, and the controller 700 is capable of executing a first refrigerant charging mode in which the refrigeration circuit is charged with refrigerant supplied from the first service valve 401 by operating the high-stage compressor 12 while the low-stage compressor 11 is stopped. As a result, the low-stage compressor 11 is stopped while refrigerant is being charged from the first service valve 401, making it easier to maintain an appropriate pressure difference. This makes it possible to reduce the load on the high-stage compressor 12 during refrigerant charging. Furthermore, in this embodiment, the gas refrigerant return pipe 60 where the first service valve 401 is located is a pipe that bypasses the gas refrigerant in the gas-liquid separator 16 to the high-stage compressor 12, and therefore has a pipe diameter of, for example, 2 minutes, which makes it easy to install the first service valve 401.

[0093] As in the present embodiment, the gas refrigerant return pipe 60 is opened and closed by the gas refrigerant flow control valve 61 provided on the opposite side of the external connection port 500A from the medium-pressure pipe 80, and the controller 700 may be configured to close the gas refrigerant flow control valve 61 in the first refrigerant charging mode. This stops the low-stage compressor 11 while refrigerant is being charged from the first service valve 401, making it easier to maintain an appropriate pressure difference. This makes it possible to reduce the load on the high-stage compressor 12 during refrigerant charging.

[0094] As in the present embodiment, the gas refrigerant return pipe 60 connects the gas-liquid separator 16 and the intermediate-pressure pipe 80 and is opened and closed by the first connection port 501A provided on the intermediate-pressure pipe 80 side relative to the external connection port 500A. The controller 700 may be configured to execute a refrigerant charging initial mode in which, with the first connection port 501A closed, all compressors 11 and 12 are stopped, and multiple valves 56, 58, 17, and 32 provided in the refrigeration circuit are closed to isolate the refrigerant flow path in the refrigeration circuit between the gas-liquid separator 16 and all of the compressors 11 and 12. This allows refrigerant to be charged into the refrigeration circuit without operating any of the compressors 11 and 12. This reduces the load on the compressors 11 and 12 during refrigerant charging.

[0095] As in the present embodiment, the controller 700 may be configured to execute the first refrigerant charging mode after executing the initial refrigerant charging mode. This allows refrigerant to be charged in the initial refrigerant charging mode without operating the high-stage compressor 12, and then the high-stage compressor 12 is operated to charge refrigerant. This makes it easier to maintain an appropriate pressure difference during refrigerant charging, and reduces the load on the high-stage compressor 12.

[0096] As in the present embodiment, the piping 72 connected to the suction port of the low-stage compressor 11 is provided with the second service valve 402, and the controller 700 may be configured to execute a second refrigerant charging mode after the first refrigerant charging mode, in which the high-stage compressor 12 and the low-stage compressor 11 are operated with the gas refrigerant flow control valve 61 open, thereby charging the refrigeration circuit with refrigerant supplied from the second service valve 402. As a result, even when the remaining amount of refrigerant in the refrigerant cylinder is low, refrigerant can be charged via the low-pressure piping 72 connected to the low-stage compressor 11. This makes it easy to charge the refrigerant to the appropriate amount.

[0097] As in this embodiment, the controller 700 may be configured to terminate the refrigerant charging mode when the rate of change of pressure in the refrigeration circuit falls below a predetermined rate. This allows the refrigerant charging mode to be terminated when it becomes difficult to charge the refrigerant into the refrigeration circuit. This makes it easier to charge the refrigerant to the appropriate amount.

[0098] As in the present embodiment, the controller 700 may be configured to include a notification unit 801, and to cause the notification unit 801 to issue a notification instructing the user to switch the connection of the external refrigerant supply tool connected to the first service valve 401 to the second service valve 402 when the first refrigerant charging mode ends. This makes it easier to charge refrigerant through the low-pressure piping 72 connected to the low-stage compressor 11 even when the remaining amount of refrigerant in the refrigerant cylinder is low. This makes it easier to charge the refrigerant to the appropriate amount.

[0099] As in the present embodiment, the controller 700 may be configured to include a memory unit 703 that stores the set temperature of the refrigeration equipment 30 having the refrigeration heat exchanger 31, and the controller 700 may be configured to operate the compressors 11 and 12 in the refrigerant charging mode in a manual mode in which the compressors 11 and 12 are operated at a fixed frequency specified by an input operation to the input unit 803, and an automatic mode in which the compressors 11 and 12 are operated at a fixed frequency corresponding to a cooling load calculated from the outside air temperature and the set temperature. This allows the operating frequencies of the compressors 11 and 12 in the refrigerant charging mode to be fixed, making it easier to determine whether the refrigerant charging amount is appropriate. This makes it easier to charge the refrigerant to the appropriate amount.

[0100] As in the present embodiment, the refrigeration circuit may be configured to be filled with carbon dioxide as a refrigerant. This allows carbon dioxide, which is a refrigerant with a particularly high pressure during filling, to be filled into the refrigeration circuit without placing a large load on the compressors 11 and 12.

[0101] (Embodiment 2) Hereinafter, embodiment 2 will be described using Figs. 12 to 15. Note that, hereinafter, description of matters similar to embodiment 1 will be omitted, and only the differences will be described. [2-1. Configuration] [2-1-1. Configuration of Refrigeration Device] Fig. 12 is a diagram showing a refrigeration circuit of a refrigeration device 101 in embodiment 2. As shown in Fig. 12, the refrigeration device 101 in embodiment 2 has a first service valve 401 in a pipe 71 that connects the medium-pressure pipe 80 and the outlet side of the indoor heat exchanger 22. Furthermore, the first service valve 401 is not provided in the gas refrigerant return pipe 60. The other configurations are the same as those of the refrigeration device 1 in embodiment 1. In this embodiment, the pipe 71 corresponds to the "first refrigerant pipe."

[0102] In the second embodiment, the first connection port 501A is connected to the pipe 71 on the side of the on-off valve 23, i.e., the side of the medium-pressure pipe 80, with respect to the external connection port 500A. The second connection port 502A is connected to the pipe 71 on the side of the indoor heat exchanger 22, with respect to the external connection port 500A. In other words, in the second embodiment, the first service valve 401 can open and close the side of the pipe 71 that faces the medium-pressure pipe 80 with respect to the external connection port 500A.

[0103] As in the first embodiment, the refrigeration device 101 has a controller 700 that stores and executes modes for controlling the refrigeration circuit, and has modes that pattern the valve opening and compressor control during refrigerant charging. The modes include, for example, an initial refrigerant charging mode, a first refrigerant amount adjustment mode, and a second refrigerant amount adjustment mode. [2-2. Operation] [2-2-1. Operation during refrigerant charging]

[0104] In the second embodiment, the controller 700 also executes each refrigerant charging mode, thereby enabling an appropriate amount of refrigerant to be charged in a refrigeration circuit with a two-stage compression configuration, and further enabling refrigerant charging to continue even when the amount of gas remaining in the refrigerant cylinder is low. Note that the sequence and triggers of the following operations are the same as those shown in Figures 4 and 7 of the first embodiment, but the open / closed states of the valves are different from those of the first embodiment. Also, the setting operations in Figure 3 are the same as those of the first embodiment, and therefore will not be described here.

[0105] 13 is a diagram showing the refrigeration circuit in the initial refrigerant charging mode of the refrigeration device 101. When starting to charge refrigerant into the refrigeration circuit after evacuation is complete, the first service valve 401 and a refrigerant cylinder filled with the refrigerant to be charged into the circuit are connected by a charge hose via a manifold gauge, and refrigerant is charged into the gas-liquid separator 16 in the initial refrigerant charging mode.

[0106] In the second embodiment, in step SB1 of FIG. 4 , the controller 700 sets the first service valve 401 to the charging mode. In step SB1, the controller 700 fully opens the indoor expansion mechanism 21, the second heating valve 57, and the throttling mechanism 17. In step SB1, the cooling inlet expansion mechanism 32, the first heating valve 52, the second cooling valve 55, the third cooling valve 56, the refrigerant return expansion mechanism 58, and the gas refrigerant flow control valve 61 are fully closed. In step SB1, the second service valve 402 is set to an operating mode that communicates only between the low-stage compressor 11 and the cooling outlet pressure adjustment mechanism 33. The operation of these valves is included as a refrigerant charging initial mode in the mode information 705 stored in the memory unit 703, and is automatically performed by the controller 700. In step SB1, the operation of the refrigeration apparatus 101 switches to the refrigerant charging initial mode.

[0107] In step SB1, the refrigeration circuit of refrigeration apparatus 101 is divided into two parts, one including gas-liquid separator 16 and the other including low-stage compressor 11 and high-stage compressor 12, by the closed valves 32, 52, 55, 56, 58, and 61 and first service valve 401. In the initial refrigerant charging mode, first service valve 401 is in the charging state, so the refrigerant supplied from external connection port 500A flows through second connection port 502A and pipe 71 to the indoor heat exchanger 22 side, and then flows into gas-liquid separator 16 through pipes 78, 76, and 79.

[0108] When the pressure P4 in the circuit becomes equal to or exceeds the pressure in the refrigerant cylinder, the pressure difference disappears and refrigerant charging becomes impossible. Therefore, as in the first embodiment, the controller 700 determines whether to switch the mode from the initial refrigerant charging mode to the first refrigerant charging mode (step SB2). If the rate of change per unit time of the pressure P4 measured by the second intermediate pressure side pressure sensor 604 becomes smaller than the first predetermined rate of change (step SB2: YES), the controller 700 ends the initial refrigerant charging mode. After the initial refrigerant charging mode ends, the controller 700 switches the refrigerant charging mode to the first refrigerant charging mode (steps SB3 and SB4).

[0109] FIG. 14 illustrates the refrigeration circuit of the refrigeration system 101 in the first refrigerant charging mode. In the first refrigerant charging mode, the controller 700 performs single-stage compression by operating only the high-stage compressor 12, lowering the intermediate pressure in the refrigerant piping connected to the first service valve 401, and creating a pressure difference between the pressure in the refrigerant cylinder and the intermediate pressure to charge the refrigerant. In the first refrigerant charging mode, the service valve 401 is fully open, connecting all of the connection ports 500A, 501A, and 502A, including the external connection port 500A. All valves other than the service valve 401 are opened to the same degree as during cooling operation. In this mode, the second service valve 402 is in an operating mode that connects only the low-stage compressor 11 and the cooling outlet pressure adjustment mechanism 33. The operation of these valves is included as the first refrigerant charging mode in the mode information 705 stored in the memory unit 703, and is automatically controlled by the controller 700.

[0110] In the first refrigerant charging mode, if the amount of refrigerant charged into the circuit increases, the intermediate pressure rises, and the pressure difference between the pressure in the refrigerant cylinder decreases, making refrigerant charging impossible. Therefore, the controller 700 determines whether to switch from the first refrigerant amount adjustment mode to the second refrigerant amount adjustment mode (step SB5). If the rate of change per hour of the high-pressure pressure P3 measured by the high-pressure-side pressure sensor 603 becomes smaller than a second predetermined rate of change (step SB5: YES), the controller 700 terminates the first refrigerant charging mode (step SB6). After the first refrigerant charging mode ends, the controller 700 causes the notification unit 801 to issue a notification (step SB7). The notification in step SB7 includes an instruction to reconnect the charge hose connected to the first service valve 401 to the connection port 500B of the second service valve 402.

[0111] After the first refrigerant charging mode ends and notification is made by the notification unit 801, the service person or the like reconnects the charge hose connected to the refrigerant cylinder to the second service valve 402.

[0112] FIG. 15 is a diagram showing the refrigeration circuit of the refrigeration system 101 in the second refrigerant charging mode. In step SC1 of FIG. 7, the second service valve 402 is fully open, connecting all three connection ports 500A, 501A, and 502A, including the external connection port 500A, and the other valves, including the first service valve 401, are set to the same settings as during cooling operation. The operation of these valves is included in the mode information 705 stored in the memory unit 703 as the second refrigerant charging mode and is automatically performed by the controller 700. Furthermore, the controller 700 operates the low-stage compressor 11 to perform two-stage compression (step SC2) to execute the second refrigerant charging mode. In the second refrigerant charging mode, the low-pressure in the refrigerant pipe connected to the second service valve 402 is reduced to create a pressure difference between the pressure in the refrigerant cylinder and the intermediate pressure, thereby charging the refrigerant. This allows refrigerant to be charged even when the amount of gas remaining in the refrigerant cylinder is low.

[0113] Thereafter, when it is confirmed that the appropriate amount of refrigerant has been charged into the circuit (step SC3: YES), the refrigerant charging is completed (step SC4). To determine whether the appropriate amount of refrigerant has been charged, for example, it is determined whether the high-pressure pressure P3 measured by the high-pressure side pressure sensor 603 is equal to the target high-pressure pressure. Thereafter, the controller 700 causes the notification unit 801 to notify that the refrigerant charging operation has ended (step SC5).

[0114] In this way, the refrigeration system 101 is equipped with a first service valve 401 in the refrigerant piping connecting the on-off valve 23 and the indoor heat exchanger 22, a second service valve 402 in the piping connecting the suction port of the low-stage compressor 11 and the chiller outlet pressure regulating mechanism 33, a controller 700 that controls the valve opening and compressor frequency, and a mode that patterns the valve opening during refrigerant charging, thereby charging the refrigeration system 101 with an appropriate amount of refrigerant while preventing overloading of the compressor and charging refrigerant when the amount of remaining gas in the refrigerant tank is low. Furthermore, in this second embodiment, the first service valve 401 can also be used for attaching and detaching the indoor heat exchanger 22 for maintenance, equipment replacement, etc., thereby reducing the number of parts in the refrigeration system 101.

[0115] [2-3. Effects, etc.] As described above, in this embodiment, the pipe 71 on which the first service valve 401 is provided connects the medium-pressure pipe 80 and the indoor heat exchanger 22, and the first service valve 401 can open and close the portion of the pipe 71 that is connected to the medium-pressure pipe 80 using the external connection port 500A as a reference. This allows the first service valve 401 to be used not only when charging refrigerant, but also for attaching and detaching the indoor heat exchanger 22 during maintenance, equipment replacement, etc. This allows the number of parts in the refrigeration system 101 to be reduced.

[0116] (Other Embodiments) As described above, Embodiments 1 and 2 have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in Embodiments 1 and 2 above to create new embodiments.

[0117] In the above-described embodiment, the refrigeration apparatus 1 includes one indoor heat exchanger 22 and one chilled-use heat exchanger 31. However, this is not limiting, and the refrigeration apparatus 1 may omit the indoor heat exchanger 22 and include multiple chilled-use heat exchangers 31. That is, the refrigeration apparatus 1 may omit the indoor unit 20 and include multiple chilled-use equipment 30. In this case, the multiple chilled-use heat exchangers 31 have different evaporation temperature ranges. Of the multiple chilled-use heat exchangers 31, the chilled-use heat exchanger 31 with a higher evaporation temperature range is connected to the inlet side of the high-stage compressor 12, and the chilled-use heat exchanger 31 with a lower evaporation temperature range is connected to the inlet side of the low-stage compressor 11.

[0118] For example, when the refrigeration system 1 includes a cooling unit 30 set to a freezing temperature range and a cooling unit 30 set to a refrigeration temperature range, the cooling heat exchanger 31 in the cooling unit 30 set to the refrigeration temperature range is connected to the inlet side of the high-stage compressor 12. On the other hand, the cooling heat exchanger 31 in the cooling unit 30 set to the freezing temperature range is connected to the inlet side of the low-stage compressor 11.

[0119] In the above-described embodiment, a plurality of use-side heat exchangers connected to the inlet side of the high-stage compressor 12 may be provided in parallel on the pipes 78 and 71. Similarly, a plurality of use-side heat exchangers connected to the inlet side of the low-stage compressor 11 may be provided in parallel on the pipes 77 and 72.

[0120] For example, a plurality of indoor heat exchangers 22 may be provided in parallel to one another in the pipe 78 and the pipe 71. In this case, an indoor expansion mechanism 21 may be provided on the inlet side of each of the indoor heat exchangers 22. In this case, the refrigeration system 1 includes a plurality of indoor units 20. Also in this case, one or more indoor heat exchangers 22 and one or more cooling heat exchangers 31 may be provided in parallel to one another in the pipe 78 and the pipe 71.

[0121] A plurality of chilled-use heat exchangers 31 may be provided in parallel to one another on the pipe 77 and the pipe 72. In this case, a chilled-use inlet-side expansion mechanism 32 may be provided on the inlet side of each chilled-use heat exchanger 31. In this case, at least one of the chilled-use heat exchangers 31 provided in parallel on the pipe 77 and the pipe 72 may have an evaporation temperature range different from that of the other chilled-use heat exchangers 31.

[0122] In the first and second embodiments, the service valves 401, 402 are described as being electronically controllable, but this is merely an example. The configuration of each service valve 401, 402 may be configured to be manually switched. That is, the operation of each service valve 401, 402 in steps SB1, SB3, SB6, SC1, and SC4 may be manually executed. In this case, for example, in steps SB1, SB3, SB6, SC1, and SC4, a notification unit 801 or the like may issue an instruction to switch the configuration of each service valve 401, 402.

[0123] In the first and second embodiments, the notification unit 801 has been described as a display including a liquid crystal panel or the like, but this is merely an example. The notification unit 801 may be configured to issue an instruction to change the connection of the charge hose of the refrigerant cylinder from the first service valve 401 to the second service valve 402. For example, the notification unit 801 may be a speaker that issues an instruction to change the connection of the charge hose by voice. The notification unit 801 may also be an LED or the like that issues an instruction to change the connection of the charge hose by light.

[0124] In the first embodiment, it has been described that the first service valve 401 is disposed between the gas refrigerant flow control valve 61 and the accumulator 13, i.e., the gas refrigerant flow control valve 61 is located closer to the gas-liquid separator 16 than the first service valve 401, but this is just one example. For example, the first service valve 401 may be configured to be disposed closer to the gas-liquid separator 16 than the gas refrigerant flow control valve 61 in the gas refrigerant return pipe 60. In this case, the first connection port 501A, which is closed when the first service valve 401 is in the charging mode, is connected to the gas refrigerant return pipe 60 on the gas-liquid separator 16 side of the external connection port 500A. Furthermore, the second connection port 502A, which is always open, is connected to the gas refrigerant return pipe 60 on the medium-pressure pipe 80 side of the external connection port 500A. In this case, the first connection port 501A corresponds to a "first opening / closing unit" that opens and closes the gas refrigerant return pipe 60. In this case, in the initial refrigerant charging mode, the gas refrigerant flow control valve 61 is closed and the first service valve 401 is fully open. In the first refrigerant charging mode, the gas refrigerant flow control valve 61 is opened and the first service valve 401 is in the charging mode, thereby closing the first connection port 501A. As a result, similar to the first embodiment, the initial refrigerant charging mode, the first refrigerant charging mode, and the second refrigerant charging mode can be used selectively without increasing the number of parts.

[0125] In the first and second embodiments, the refrigeration circuit of the refrigeration apparatus 1, 101 is described as being provided with the first service valve 401 and the second service valve 402, but this is merely an example. For example, instead of providing the second service valve 402, a bypass pipe may be branched off near the first service valve 401, connected to the suction side of the low-stage compressor 11, and an on-off valve may be provided in the bypass pipe. In this case, by opening the on-off valve provided in the bypass pipe only in the second refrigerant charging mode, it is not necessary to change the connection of the charge hose, and the refrigerant charging work is simplified.

[0126] In the first embodiment, when each refrigerant charging mode is executed in the automatic mode, the compressors 11 and 12 are operated at the frequency calculated in step SA5. However, this is only an example. For example, in the automatic mode, the compressors 11 and 12 may be configured to operate at full capacity and fix the frequency.

[0127] The controller 700 in the present disclosure may be any device capable of controlling the device in the present disclosure. When describing the subject matter of the invention, the device controlled by the controller 700 may be referred to as a control means, a control unit, or similar terms in addition to the controller 700. The controller can be implemented in various forms. For example, a processor may be used as the controller 700. Using a processor as the controller 700 enables various processes to be performed by loading a program from a storage medium storing the program into the processor and executing the program. This allows the processing content to be changed by changing the program stored in the storage medium, thereby increasing the flexibility in changing the control content. Examples of processors include a CPU (Central Processing Unit) and an MPU (Micro-Processing Unit). Examples of storage media include a hard disk, flash memory, and optical disk. Furthermore, the controller 700 may be wired logic, which does not allow the program to be rewritten. Using wired logic as the controller 700 is effective in improving processing speed. An example of wired logic is an ASIC (Application Specific Integrated Circuit). The controller 700 may be implemented by combining a processor and wired logic. By implementing the controller 700 by combining a processor and wired logic, it is possible to increase the flexibility of software design while improving processing speed. The controller 700 and a circuit having a different function from the controller 700 may be configured with a single semiconductor element. An example of a circuit having a different function is an A / D and D / A conversion circuit. The controller 700 may be configured with a single semiconductor element or multiple semiconductor elements. When configured with multiple semiconductor elements, each control described in the claims may be implemented with a different semiconductor element. The controller 700 may also be configured with a semiconductor element and passive components such as resistors or capacitors.

[0128] Furthermore, for example, the step units of operation shown in Figures 3, 4, and 7 are divided according to the main processing content in order to make it easier to understand the operation of each part of the refrigeration device 1, and the present disclosure is not limited by the way in which the processing units are divided or the names thereof.

[0129] (Embodiment 3) (Knowledge and other information that forms the basis of the present disclosure) When the inventors came up with the refrigeration apparatus of the second aspect of the present disclosure, there was a technology that allowed for safe refrigerant replacement in a refrigeration apparatus equipped with a refrigeration cycle that uses a flammable refrigerant as the operating refrigerant. In this refrigerant replacement method, after refrigerant recovery, a pump that performs vacuuming and a refrigerant cylinder that performs refrigerant charging are connected to the refrigeration cycle via a service valve, and the refrigeration cycle is then vacuumed and the refrigerant is recharged. In such a refrigeration apparatus, external devices such as a refrigerant recovery device and a humidity control unit are connected via connecting devices other than the service valve.

[0130] The present inventors have discovered that such a refrigeration apparatus requires an increased number of components for connecting external devices, which increases costs and may make the work of connecting external devices more complicated. The present disclosure provides a refrigeration apparatus that can easily connect multiple types of external devices.

[0131] A third embodiment corresponding to the second aspect of the present disclosure will now be described with reference to the accompanying drawings. 3-1-1. Configuration of the Refrigeration Device FIG. 16 is a diagram illustrating a refrigeration circuit of a refrigeration device 201 according to the third embodiment. For ease of explanation, in FIG. 16, the valve body in the open state is shown in white, and the valve body and expansion mechanism in the closed state are shown in black. In FIG. 16, an external device 405 and the piping connecting the external device to the refrigeration circuit are indicated by two-dot chain lines. For ease of explanation, in FIG. 16, piping through which the refrigerant flows is indicated by thick lines, and piping through which no refrigerant flows is indicated by thin lines. The refrigeration circuit uses carbon dioxide (R744), a natural refrigerant that is neither flammable nor toxic. As shown in FIG. 16, the refrigeration device 201 includes an outdoor unit 210, an indoor unit 220, and cooling equipment 230. The indoor unit 220 provides air conditioning for the interior of a store such as a convenience store or supermarket, and the refrigeration equipment 230 provides cooling for the interior of refrigerated showcases or freezer showcases that serve as cooling storage facilities installed within the store.

[0132] The refrigeration system 201 includes an outdoor unit 210 configured by sequentially connecting a two-stage compressor including a low-stage compressor 211 and high-stage compressors 212, 212, a first switching mechanism 250, an outdoor heat exchanger 215, a second switching mechanism 254, and a gas-liquid separator 216. The two high-stage compressors 212, 212 are connected in parallel to the low-stage compressor 211. An accumulator 213 is disposed between the low-stage compressor 211 and the high-stage compressor 212. The refrigerant discharged from the low-stage compressor 211 is separated into gas and liquid by the accumulator 213, and the gas refrigerant is sent to the high-stage compressor 212.

[0133] An oil separator 214 is connected to the discharge downstream side of the high-stage compressor 212. A first switching mechanism 250 is connected to the oil separator 214, and an outdoor heat exchanger 215 is connected to the first switching mechanism 250. The first switching mechanism 250 includes a pipe 240 connecting the oil separator 214 and the outdoor heat exchanger 215, and a first cooling valve (first on-off valve) 251 is connected to the pipe 240. A first heating pipe 241 is connected to the pipe 240 upstream of the first cooling valve 251. The first heating pipe 241 includes a first heating valve 252 (second on-off valve). The first heating pipe 241 is connected to a pipe 271 connecting the indoor heat exchanger 222 of the indoor unit 220 and the suction side of the high-stage compressor 212. An on-off valve 223 is connected to the pipe 271 .

[0134] A first outdoor return pipe 242 is connected to the pipe 240 downstream of the first cooling valve 251. The first outdoor return pipe 242 is equipped with an outdoor refrigerant return valve (third on-off valve) 253. The first outdoor return pipe 242 is connected to a pipe 272 that connects the cooling-use heat exchanger 231 of the cooling equipment 230 to the suction side of the low-stage compressor 211, and a cooling-use outlet-side pressure adjustment mechanism 233 of the cooling equipment 230 is connected to this pipe 272.

[0135] A second switching mechanism 254 is connected to the outdoor heat exchanger 215, and a gas-liquid separator 216 is connected to the second switching mechanism 254. The second switching mechanism 254 is formed by annularly connecting the ends of first to fourth pipes 273, 274, 275, and 276 at connectors A, B, C, and D. A second cooling valve (first control valve) 255 and a check valve 259 are disposed in the first pipe 273, a refrigerant return expansion mechanism (second control valve) 258 that controls the flow rate is disposed in the second pipe 274, and a third cooling valve (third control valve) 256 and a check valve 259 are disposed in the third pipe 275. Furthermore, a second heating valve (fourth control valve) 257 and a check valve 259 are disposed in the fourth pipe 276.

[0136] A connection A between the second cooling valve 255 and the refrigerant return expansion mechanism 258 is connected to the outdoor heat exchanger 215, and a connection B between the refrigerant return expansion mechanism 258 and the third cooling valve 256 is connected to a pipe 277 connecting the gas-liquid separator 216 and the cooling heat exchanger 231. The cooling inlet expansion mechanism 232 is connected to this pipe 277. A connection C between the third cooling valve 256 and the second heating valve 257 is connected to the indoor heat exchanger 222 via a pipe (second cooling pipe) 278. The indoor expansion mechanism 221 of the indoor unit 220 is connected to the second cooling pipe 243. A connection D between the second heating valve 257 and the second cooling valve 255 is connected to the gas-liquid separator 216 via a pipe 279. A throttle mechanism 217 is disposed in the pipe 279.

[0137] As described above, the indoor heat exchanger 222 is a user-side heat exchanger provided in the indoor unit 220. When the indoor unit 220 performs cooling operation, the indoor heat exchanger 222 functions as an evaporator, and the evaporation temperature thereof is determined by the opening degree of the indoor expansion mechanism 221. In this embodiment, the evaporation temperature of the indoor heat exchanger 222 is determined in accordance with the indoor temperature set in the indoor unit 220. The evaporation temperature range of the indoor heat exchanger 222 is, for example, 3°C to 6°C.

[0138] As described above, the refrigeration heat exchanger 231 is a user-side heat exchanger provided in the refrigeration equipment 230. The refrigeration heat exchanger 231 functions as an evaporator, and the evaporation temperature thereof is determined by the opening degree of the refrigeration inlet-side expansion mechanism 232. In this embodiment, the evaporation temperature of the refrigeration heat exchanger 231 is determined according to the internal temperature set in the refrigeration equipment 230.

[0139] The refrigeration equipment 230 of this embodiment can select and set the temperature zone inside the storage unit, for example, either a partial temperature zone (-3°C to -1°C) or a freezing temperature zone (-20°C to -18°C).

[0140] When the temperature zone inside the refrigerator is the partial temperature zone, the evaporation temperature zone of the refrigeration heat exchanger 231 is, for example, -12°C to 0°C. Specifically, when the refrigeration equipment 230 stores fruits and vegetables, the evaporation temperature zone of the refrigeration heat exchanger 231 is, for example, -5°C to 0°C. When the refrigeration equipment 230 stores dressed meat or fresh fish, the evaporation temperature zone of the refrigeration heat exchanger 231 is, for example, -12°C to -8°C. When the temperature zone inside the refrigerator is the freezing temperature zone, the evaporation temperature zone of the refrigeration heat exchanger 231 is, for example, -40°C to -20°C. For this reason, the evaporation temperature zone of the refrigeration heat exchanger 231 is set lower than the temperature zone inside the refrigerator.

[0141] In this way, two use-side heat exchangers with different evaporation temperature ranges are provided in the refrigeration device 201. Of these two use-side heat exchangers with different evaporation temperature ranges, the indoor heat exchanger 222 is connected to the inlet side of the high-stage compressor 212, and the cooling heat exchanger 231, which has a lower evaporation temperature range than the indoor heat exchanger 222, is connected to the inlet side of the low-stage compressor 211. The indoor heat exchanger 222 corresponds to the "first use-side heat exchanger" in this disclosure, and the cooling heat exchanger 231 corresponds to the "second use-side heat exchanger" in this disclosure.

[0142] A gas refrigerant return pipe 260 is connected to the gas-liquid separator 216, and the gas refrigerant return pipe 260 is connected to a pipe 271 and then to the accumulator 213. A gas refrigerant flow control valve 261 is connected to the gas refrigerant return pipe 260. In the present embodiment, a portion of the gas refrigerant separated in the gas-liquid separator 216 has its flow rate adjusted by the gas refrigerant flow control valve 261, is sent to the accumulator 213, and is returned to the suction side of the high-stage compressor 212.

[0143] In the refrigeration device 201, by controlling the opening of the gas refrigerant flow control valve 261 and adjusting the amount of gas refrigerant returning, the refrigerant pressure becomes higher on the inlet side of the indoor expansion mechanism 221 than on the outlet side of the indoor heat exchanger 222. In other words, in the refrigeration device 201, it is possible to generate a refrigerant pressure difference between the inlet side and outlet side of the indoor heat exchanger 222 in the refrigeration circuit.

[0144] As a result, in the refrigeration device 201, in the indoor heat exchanger 222 where the evaporation temperature of the refrigerant is high, it is possible to control the refrigerant flowing through the indoor heat exchanger 222 at a pressure value obtained by adding a specified pressure value to the pressure value at which the refrigerant becomes the evaporation temperature of the refrigerant. Therefore, in the refrigeration device 201, carbon dioxide (R744), a natural refrigerant with high environmental friendliness, is used, which makes it possible to improve the efficiency of the air conditioning temperature range and the efficiency of the entire refrigeration system.

[0145] [1-1-2. Configuration for connecting external equipment to the refrigeration apparatus] In the third embodiment, a throttling mechanism 217 is connected between the second switching mechanism 254 and the gas-liquid separator 216. The throttling mechanism 217 is provided in a pipe 279. In the pipe 279, a first service valve 301 is disposed upstream of the throttling mechanism 217, and a second service valve 302 is disposed downstream of the throttling mechanism 217.

[0146] The first service valve 301 has three connection ports. One is an external connection port 390 that can connect a vacuum unit, a refrigerant sealing unit, and external equipment 405, and of the remaining two connection ports, one is connected to connection part D of the second switching mechanism 254, and the other is connected to the throttling mechanism 217. The second service valve 302 has three connection ports. One is an external connection port 390 that can connect a vacuum unit, a refrigerant sealing unit, and external equipment 405, and of the remaining two connection ports, one is connected to the throttling mechanism 217, and the other is connected to the gas-liquid separator 216.

[0147] Each service valve 301, 302 is connected in one of three ways: blocking the external connection port 390 and connecting the remaining two connection ports; connecting all three connection ports including the external connection port 390; or connecting the external connection port 390 with one of the remaining two connection ports.

[0148] As described above, the external connection port 390 of the first service valve 301 and the external connection port 390 of the second service valve 302 are formed so as to be connectable to a vacuum unit, a refrigerant sealing unit, and multiple types of external equipment 405.

[0149] The vacuum unit is a unit capable of performing a vacuuming operation, which is an operation of discharging air from piping provided in the refrigeration circuit of the refrigeration device 201. The vacuum unit includes, for example, piping such as hoses connectable to the external connection port 390 of the first service valve 301 and the external connection port 390 of the second service valve 302, a valve body capable of opening and closing the hoses, and a vacuum pump connected to the hoses.

[0150] A refrigerant charging unit can be connected later to the external connection port 390 of the first service valve 301 and the external connection port 390 of the second service valve 302 instead of the vacuum unit described above. The refrigerant charging unit is a unit that charges refrigerant into the refrigeration circuit of the refrigeration device 201. The refrigerant charging unit includes, for example, piping such as hoses that can be connected to the external connection port 390 of the first service valve 301 and the external connection port 390 of the second service valve 302, a valve body that can open and close the hoses, and a refrigerant cylinder connected to the hoses.

[0151] Furthermore, instead of the above-described vacuum unit and refrigerant charging unit, a refrigerant recovery unit can be connected later as external equipment 405 to external connection port 390 of first service valve 301 and external connection port 390 of second service valve 302. The refrigerant recovery unit is a unit that recovers refrigerant from the refrigeration circuit of refrigeration device 201. The refrigerant charging unit includes, for example, piping such as hoses connectable to external connection port 390 of first service valve 301 and external connection port 390 of second service valve 302, a valve body that can open and close the hoses, a refrigerant tank connected to the hoses, and a refrigerant recovery machine.

[0152] An external device 405 can be retrofitted and connected in parallel to the throttle mechanism 217 between the external connection port 390 of the first service valve 301 and the external connection port 390 of the second service valve 302. An example of this external device 405 is the humidity control device 350 shown in Figures 17 and 18.

[0153] FIG. 17 is a schematic side view showing an embodiment of a humidity control apparatus. FIG. 18 is a schematic front view showing an embodiment of a humidity control apparatus 350. As shown in FIGS. 17 and 18 , the humidity control apparatus 350 includes a heating heat exchanger 306, a cooling / dehumidifying heat exchanger 307, and a blower 308. The blower 308 is a device that causes air to flow through the cooling / dehumidifying heat exchanger 307 and then the heating heat exchanger 306. Arrow X1 in FIG. 17 indicates the direction of air flow. A refrigerant pipe 310 is connected to the refrigerant inlet side of the heating heat exchanger 306. A throttling mechanism 311 is provided midway through the refrigerant pipe 312 that connects the refrigerant outlet side of the heating heat exchanger 306 and the refrigerant inlet side of the cooling / dehumidifying heat exchanger 307. A throttling mechanism 313 is provided midway through the refrigerant pipe 312.

[0154] A drain pan 315 for storing condensed water is installed below the heating heat exchanger 306 and the cooling and dehumidifying heat exchanger 307. The drain pan 315 is inclined downward from the cooling and dehumidifying heat exchanger 307 toward the heating heat exchanger 306, and is configured to store condensed water heated by the heating heat exchanger 306. A drain pipe 316 for draining condensed water is installed below the drain pan 315, and a drain control valve 317 is installed in the drain pipe 316. An evaporation sheet 318 for absorbing condensed water stored in the drain pan 315 is installed downstream of the heating heat exchanger 306.

[0155] A humidity sensor 319 is provided near the cooling and dehumidifying heat exchanger 307 to detect the humidity of the air flowing into the cooling and dehumidifying heat exchanger 307. Based on the detection result of the humidity sensor 319, the opening degrees of the throttling mechanism 311 of the heating heat exchanger 306 and the throttling mechanism 313 of the cooling and dehumidifying heat exchanger 307 are adjusted. The drain pan 315 is equipped with a sterilization device 320 that sterilizes condensed water stored in the drain pan 315. An electrostatic atomizer, for example, is used as the sterilization device 320.

[0156] The humidity control device 350 can be installed anywhere indoors where dehumidification is desired. For example, in convenience stores, condensation can form on the ceiling due to radiant heat from flat, open-top showcases, which can lead to mold growth. In this case, the humidity control device 350 is installed so that it can blow air toward the ceiling of the space to be conditioned.

[0157] [3-2. Operation and Effects] Next, the operation of this embodiment will be described.

[0158] [3-2-1. Cooling Operation] First, the operation of performing the cooling operation will be described. During the cooling operation, as shown in Fig. 16, the outdoor heat exchanger 215 is used as a gas cooler or a radiator, and the indoor heat exchanger 222 and the cooling heat exchanger 231 are used as evaporators. When performing the cooling operation, the first switching mechanism 250 opens the first cooling valve 251 and closes the remaining first heating valve 252 and the outdoor refrigerant return valve 253. Furthermore, the second switching mechanism 254 opens the second cooling valve 255 and the third cooling valve 256 and closes the second heating valve 257 and the refrigerant return expansion mechanism 258. In this state, by driving the low-stage compressor 211 and each high-stage compressor 212, the refrigerant compressed by the low-stage compressor 211 is sent to each high-stage compressor 212, further compressed by each high-stage compressor 212, and discharged toward the oil separator 214.

[0159] The refrigerant that has passed through the oil separator 214 is sent to the outdoor heat exchanger 215 through the first cooling valve 251 of the first switching mechanism 250, where it exchanges heat with outdoor air. The refrigerant after heat exchange is sent from connection A of the second switching mechanism 254 to the gas-liquid separator 216 via the second cooling valve 255. The refrigerant separated in the gas-liquid separator 216 passes through piping 277 to connection B of the second switching mechanism 254. One of the refrigerants branched at connection B is sent to the indoor heat exchanger 222 via the third cooling valve 256 and the indoor expansion mechanism 221 of the indoor unit 220. In the indoor heat exchanger 222, the refrigerant exchanges heat with indoor air, cooling the indoor air. The refrigerant that has exchanged heat with the indoor air passes through the pipe 271 and is returned to the suction side of each high-stage compressor 212 via the on-off valve 223 and the accumulator 213 .

[0160] The other refrigerant branched at connection point B is sent to a refrigeration heat exchanger 231 via a refrigeration inlet side expansion mechanism 232 of the refrigeration equipment 230, where it undergoes heat exchange and cools the refrigeration equipment 230. The refrigerant that has undergone heat exchange in the refrigeration heat exchanger 231 is returned to the low-stage compressor 211 via a refrigeration outlet side pressure adjustment mechanism 233.

[0161] [3-2-2. Heating Operation] Next, the operation when the first heating operation (heating operation) is performed will be described. FIG. 19 is a circuit diagram of the refrigeration system 201 showing the heating operation. The flow of refrigerant is indicated by arrows in the figure. The first heating operation is performed using the indoor heat exchanger 222 as a gas cooler or radiator and the cooling heat exchanger 231 as an evaporator. As shown in FIG. 19, when the heating operation is performed, the first switching mechanism 250 opens the first heating valve 252 and closes the remaining first cooling valve 251 and outdoor refrigerant return valve 253. Furthermore, the second switching mechanism 254 opens the second heating valve 257 and closes the second cooling valve 255, the third cooling valve 256, and the refrigerant return expansion mechanism 258.

[0162] In this state, by driving low-stage compressor 211 and each high-stage compressor 212, the refrigerant compressed by low-stage compressor 211 is sent to each high-stage compressor 212, where it is further compressed and discharged toward oil separator 214. The refrigerant that has passed through oil separator 214 passes through first heating valve 252 of first switching mechanism 250 and is sent to indoor heat exchanger 222, where it exchanges heat with indoor air to heat the indoor air.

[0163] The refrigerant that has exchanged heat in the indoor heat exchanger 222 passes through the indoor expansion mechanism 221, reaches connection point C of the second switching mechanism 254, and is sent to the gas-liquid separator 216 via the second heating valve 257. The refrigerant separated in the gas-liquid separator 216 passes through piping 277, reaches connection point B of the second switching mechanism 254, and is sent to the chiller heat exchanger 231 via the chiller inlet expansion mechanism 232. This refrigerant undergoes heat exchange in the chiller heat exchanger 231 and cools the chiller equipment 230. The refrigerant that has exchanged heat in the chiller heat exchanger 231 passes through piping 272 and is returned to the suction side of the low-stage compressor 211 via the chiller outlet pressure adjustment mechanism 233. In the refrigeration apparatus 201 of the present disclosure, during heating, the indoor heat exchanger 222 functions as a gas cooler or a radiator, and the outdoor heat exchanger 215 is not used.

[0164] [3-2-3. Operation When Heat Absorption by Refrigeration Equipment is Insufficient to Produce Heat] Next, we will explain the operation of performing the second heating operation at full capacity when the heat absorption by the refrigeration equipment 230 is insufficient, for example, when the outdoor air temperature is lower than the temperature inside the refrigeration equipment 230. FIG. 20 is a circuit diagram of the refrigeration system 201 illustrating the heating operation when the heat absorption by the refrigeration equipment is insufficient to produce heat. The refrigerant flow is indicated by arrows in the figure. The second heating operation is performed using the indoor heat exchanger 222 as a gas cooler or radiator, and the refrigeration heat exchanger 231 and the outdoor heat exchanger 215 as evaporators. When performing the second heating operation at full capacity, the first switching mechanism 250 opens the first heating valve 252 and the outdoor refrigerant return valve 253 and closes the first cooling valve 251. In the second switching mechanism 254, the second heating valve 257 and the refrigerant return expansion mechanism 258 are opened, and the second cooling valve 255 and the third cooling valve 256 are closed.

[0165] In this state, by driving low-stage compressor 211 and each high-stage compressor 212, the refrigerant compressed by low-stage compressor 211 is sent to each high-stage compressor 212, where it is further compressed and discharged toward oil separator 214. The refrigerant that has passed through oil separator 214 is sent to indoor heat exchanger 222 through first heating valve 252 of first switching mechanism 250, where it exchanges heat with indoor air to heat the indoor air.

[0166] The refrigerant that has exchanged heat in the indoor heat exchanger 222 is sent to the gas-liquid separator 216 via the second heating valve 257 of the second switching mechanism 254. The refrigerant separated in the gas-liquid separator 216 reaches the connection B of the second switching mechanism 254 through piping 277. One of the refrigerants branched at connection B passes through the refrigerant return expansion mechanism 258 of the second switching mechanism 254 and connection A and is sent to the outdoor heat exchanger 215, where it exchanges heat with outside air. The other refrigerant branched at connection B is sent to the cooling-unit heat exchanger 231 via the cooling-unit inlet-side expansion mechanism 232, where it exchanges heat and cools the cooling-unit equipment 230. The refrigerant that has exchanged heat in the cold-air heat exchanger 231 and the refrigerant that has exchanged heat in the outdoor heat exchanger 215 and is sent from the first outdoor return pipe 242 are joined in pipe 272 and returned to the suction side of the low-stage compressor 211.

[0167] The refrigerant that has exchanged heat in the refrigeration heat exchanger 231 is adjusted by the refrigeration outlet pressure adjustment mechanism 233 so that its pressure is the same as that of the refrigerant sent from the first outdoor return pipe 242. This is the operation when the outside air temperature is lower than the temperature inside the refrigeration equipment 230.

[0168] This allows the heat absorption by the refrigeration heat exchanger 231 and the heat pumped up by the outdoor heat exchanger 215 to be used as heat for the indoor heat exchanger 222, making it possible to increase the heating capacity when the heat absorption by the refrigeration equipment 230 is insufficient.

[0169] In this case, if the outside air temperature becomes lower than the temperature inside the refrigerator 230, heat cannot be pumped from the outdoor heat exchanger 215 unless the evaporation temperature of the refrigerator 230 is lowered. Lowering the evaporation temperature of the refrigerator 230 will result in a temperature lower than the specified temperature, shortening the thermocycle and resulting in short-cycle operation, which may further reduce operating efficiency and increase power consumption. In this embodiment, the above-mentioned problems can be avoided by controlling the opening of the refrigerator outlet pressure adjustment mechanism 233 to balance the pressure with the refrigerant sent from the outdoor heat exchanger 215.

[0170] [3-2-4. Operation When High Capacity of the Cooling Equipment is Requirement but Heating Heat is Not Required] Next, operation when high capacity of the cooling equipment 230 is required but heating heat is not required will be described. FIG. 21 is a circuit diagram of the refrigeration system 201 illustrating operation when heating heat is not required. The refrigerant flow is indicated by arrows in the figure. As shown in FIG. 21, the third heating operation is performed using the outdoor heat exchanger 215 and the indoor heat exchanger 222 as gas coolers or radiators, and the cooling heat exchanger 231 as an evaporator. When performing the third heating operation, the first switching mechanism 250 opens the first cooling valve 251 and the first heating valve 252 and closes the outdoor refrigerant return valve 253. The second switching mechanism 254 opens the second cooling valve 255 and the second heating valve 257 and closes the third cooling valve 256 and the refrigerant return expansion mechanism 258.

[0171] In this state, by driving the low-stage compressor 211 and each high-stage compressor 212, the refrigerant compressed by the low-stage compressor 211 is sent to each high-stage compressor 212, further compressed by each high-stage compressor 212, and discharged toward the oil separator 214.

[0172] The refrigerant that has passed through the oil separator 214 is sent to the outdoor heat exchanger 215 through the first cooling valve 251 of the first switching mechanism 250, and at the same time, is sent to the indoor heat exchanger 222 through the first heating valve 252. The outdoor heat exchanger 215 and the indoor heat exchanger 222 function as a gas cooler or a radiator, exchanging heat with outdoor air in the outdoor heat exchanger 215 and with indoor air in the indoor heat exchanger 222, thereby heating the indoor air. The refrigerant that has exchanged heat in the outdoor heat exchanger 215 reaches the second cooling valve 255 from a connection A of the second switching mechanism 254, and the refrigerant that has exchanged heat in the indoor heat exchanger 222 reaches the second heating valve 257 from a connection C of the second switching mechanism 254, where they join and are sent to the gas-liquid separator 216. The refrigerant separated in the gas-liquid separator 216 is sent through a pipe 277 to a chilled heat exchanger 231, where it undergoes heat exchange and cools the chilled equipment 230. The refrigerant that has exchanged heat in the chilled heat exchanger 231 is returned to the suction side of the low-stage compressor 211 via a chilled outlet pressure adjustment mechanism 233.

[0173] According to this, during heating operation, the heat absorbed by the cooling equipment 230 can be dissipated by the outdoor heat exchanger 215 and the indoor heat exchanger 222, thereby increasing the cooling capacity of the cooling equipment 230 and making it possible to remove frost that has adhered to the outdoor heat exchanger 215.

[0174] [3-2-5. Operation of Refrigeration Apparatus When External Device is Connected] As described above, in the refrigeration apparatus 201, external device 405 can be connected to the external connection port 390 of the first service valve 301 and the external connection port 390 of the second service valve 302. When external device 405 is not connected, as shown in Fig. 16, the external connection port 390 of each of the service valves 301 and 302 is shut off and the other two connection ports are open.

[0175] [3-2-5-1. Vacuum Drawing] When the refrigeration device 201 is newly installed or when the refrigerant in the refrigeration device 201 is replaced, the refrigeration device 201 is subjected to a vacuum drawing operation.

[0176] When this vacuuming operation is performed, the external connection port 390 of either of the service valves 301 and 302 is opened, and the other two connection ports are closed. In this state, a vacuuming unit is connected to the opened external connection port 390. Then, in either of the service valves 301 and 302 to which the vacuuming unit is connected, the connection ports other than the external connection port 390 are opened. Then, the vacuum pump is driven to vacuum the refrigeration device 201. When the vacuuming operation is completed, the connection ports other than the external connection port 390 are closed, and the vacuuming unit is removed from the external connection port 390. This makes it possible to fill the refrigeration device 201 with refrigerant.

[0177] [3-2-5-2. Refrigerant Charging] In the refrigeration device 201, refrigerant is charged or sealed in, for example, when the refrigerant is newly installed as described above, when the refrigerant inside the refrigeration device 201 is removed for repair or replacement of the refrigeration circuit, or when the amount of refrigerant is insufficient.

[0178] When a refrigerant charging unit is connected to service valve 301 during refrigerant charging work, external connection port 390 and the other two connection ports, one of which is located on the throttle mechanism 217 side, are opened in refrigeration device 201. In this case, the other two connection ports, one of which is located on the second switching mechanism 254 side, is closed in service valve 301.

[0179] When a refrigerant charging unit is connected to service valve 302 during refrigerant charging work, external connection port 390 and the other two connection ports, one of which is located on the gas-liquid separator 216 side, are opened in refrigeration device 201. In this case, the other two connection ports, one of which is located on the throttle mechanism 217 side, is closed in service valve 302.

[0180] Thereafter, in the refrigeration device 201, with the operation of the low-stage compressor 211 and the high-stage compressor 212 stopped, the refrigerant from the refrigerant charging unit is charged into the refrigeration circuit by utilizing the pressure difference between the pressure of the refrigerant charging unit and the pressure inside the refrigeration circuit provided in the refrigeration device 201. This allows the refrigerant sent out from the refrigerant charging unit to flow directly into the gas-liquid separator 216 and be stored therein.

[0181] When the pressure difference between the pressure in the refrigeration circuit of refrigeration apparatus 201 and the pressure in the refrigerant charging unit disappears, the refrigerant in the refrigerant charging unit stops being sent to the refrigeration circuit. In this case, one of service valves 301, 302 to which the refrigerant charging unit is connected opens external connection port 390 and the other two connection ports. Then, in refrigeration apparatus 201, the operation of low-stage compressor 211 and high-stage compressor 212 is resumed, thereby filling the refrigerant into the refrigeration circuit. When the refrigerant charging is complete, all connection ports other than external connection port 390 are shut off, and the refrigerant charging unit is removed from external connection port 390.

[0182] [3-2-5-3. Recovery of Refrigerant] As described above, when the refrigeration circuit of the refrigeration device 201 is repaired or replaced, a refrigerant recovery operation is performed to recover the refrigerant inside the refrigeration device 201.

[0183] In this refrigerant recovery operation, first, external connection port 390 of first service valve 301 is opened and the other two connection ports are closed. In this state, a refrigerant recovery unit is connected to external connection port 390 of service valve 301. Thereafter, the connection ports of service valve 301 other than external connection port 390 are opened.

[0184] In the refrigeration apparatus 201, the two-stage compressor is driven with the throttling mechanism 217 closed. When the two-stage compressor is driven, as shown in FIG. 16 , the refrigerant flows sequentially through the gas-liquid separator 216, the second switching mechanism 254, the indoor heat exchanger 222, and the cold-air heat exchanger 231 before being drawn into the two-stage compressor. The refrigerant is then discharged from the two-stage compressor, passes sequentially through the outdoor heat exchanger 215 and the second switching mechanism 254, and is recovered in the refrigerant recovery unit. When the refrigerant recovery is complete, all connections other than the external connection port 390 are shut off, and the refrigerant recovery unit is removed from the external connection port 390. This allows the refrigeration apparatus 201 to be vacuumed, refrigerant charging, or refrigeration circuit maintenance.

[0185] In the refrigerant recovery operation, in the refrigeration apparatus 201, the two-stage compressor may be driven with the connection port connected to the connection portion D of the second switching mechanism 254 closed, instead of the throttling mechanism 217. Furthermore, for example, the refrigerant recovery unit may be connected to the service valve 302.

[0186] In this way, in the refrigeration apparatus 201, by connecting multiple types of external equipment 405 to the service valves 301, 302, which can connect to a vacuum unit and a refrigerant charging unit, it is possible to recover refrigerant and control the humidity of a specified space. That is, in the refrigeration apparatus 201, the service valves 301, 302 are shared as connection parts for multiple types of external equipment 405 with different uses. Therefore, in the refrigeration apparatus 201, an increase in the number of parts related to connecting the external equipment 405 can be suppressed, and the structure of the refrigeration apparatus 201 can be simplified. Furthermore, in the refrigeration apparatus 201, it is possible to simplify the work related to connecting the external equipment 405.

[0187] (Other Embodiments) As described above, the third embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the third embodiment above to create new embodiments.

[0188] In the above-described embodiment, the humidity control device 350 and the refrigerant recovery unit are described as external devices 405 that can be connected to the refrigeration device 201 via the first service valve 301 and the second service valve 302. However, the external device 405 is not limited to this, and may be, for example, an external cooling device. This external cooling device includes a heat exchanger and, when connected to the refrigeration device 201, increases the cooling capacity of at least one of the heat exchangers included in the refrigeration device 201, such as the outdoor heat exchanger 215, the indoor heat exchanger 222, and the cold-air heat exchanger 231.

[0189] Furthermore, for example, external device 405 may be a refrigerant flow rate adjusting device. This refrigerant flow rate adjusting device is a device that includes a storage unit such as a tank that can store a refrigerant or a heat exchanger, and that stores the refrigerant flowing through refrigeration device 201, thereby adjusting the flow rate of the refrigerant in refrigeration device 201 in accordance with an increase or decrease in the cooling capacity of refrigeration device 201.

[0190] Furthermore, for example, the first service valve 301 and the second service valve 302 may be provided with couplings that can connect multiple types of external devices 405 for different purposes. These couplings are, for example, tee couplings. When such couplings are provided on at least one of the first service valve 301 and the second service valve 302, multiple external devices 405 can be connected to the refrigeration apparatus 201 via the couplings. This allows, for example, the refrigeration apparatus 201 to be connected to a refrigerant recovery unit as the external device 405, while the humidity control apparatus 350 is connected. Therefore, in the refrigeration apparatus 201, while an external device 405 such as the humidity control apparatus 350 is running, other external devices 405 can be driven, such as for charging additional refrigerant.

[0191] Furthermore, for example, in the external device 405, the connection portion connectable to the first service valve 301 and the second service valve 302 may be formed so that another external device 405 can be connected thereto.

[0192] Furthermore, for example, when an external device 405 is connected to the first service valve 301 and the second service valve 302, the external connection port 390 and the other two connection ports may be kept open at all times. This allows the refrigeration device 201 to suppress liquid expansion of the refrigerant in the refrigeration circuit.

[0193] In the above-described embodiment, the refrigeration apparatus 201 includes one indoor heat exchanger 222 and one chilled-use heat exchanger 231. However, this is not limiting, and the refrigeration apparatus 201 may omit the indoor heat exchanger 222 and include multiple chilled-use heat exchangers 231. That is, the refrigeration apparatus 201 may be a chilled-use system that omits the indoor unit 220 and includes multiple chilled-use devices 230. In this case, the multiple chilled-use heat exchangers 231 have different evaporation temperature ranges. Of the multiple chilled-use heat exchangers 231, the chilled-use heat exchanger 231 with a higher evaporation temperature range is connected to the inlet side of the high-stage compressor 212, and the chilled-use heat exchanger 231 with a lower evaporation temperature range is connected to the inlet side of the low-stage compressor 211.

[0194] For example, when refrigeration device 201 includes refrigeration equipment 230 set to the freezing temperature range and refrigeration equipment 230 set to the refrigeration temperature range, refrigeration heat exchanger 231 in refrigeration equipment 230 set to the refrigeration temperature range is connected to the inlet side of high-stage compressor 212. In contrast, in refrigeration equipment 230 set to the freezing temperature range, refrigeration heat exchanger 231 is connected to the inlet side of low-stage compressor 211.

[0195] In the above-described embodiment, the refrigeration device 201 includes one indoor heat exchanger 222 and one cooling heat exchanger 231. However, the present invention is not limited to this. The refrigeration device 201 may omit the cooling heat exchanger 231 and include multiple indoor heat exchangers 222. That is, the refrigeration device 201 may be an air conditioner that omits the cooling equipment 230 and includes multiple indoor units 220. Furthermore, for example, the refrigeration device 201 may be a hot water heater, a water heater, or the like. That is, the refrigeration device 201 may be any heat pump device that includes a gas-liquid separator 216 and a throttling mechanism 217 provided on the inlet side of the gas-liquid separator 216.

[0196] In the above-described embodiment, a plurality of use-side heat exchangers connected to the inlet side of the high-stage compressor 212 may be provided in parallel on the pipes 278 and 271. Similarly, a plurality of use-side heat exchangers connected to the inlet side of the low-stage compressor 211 may be provided in parallel on the pipes 277 and 272.

[0197] Furthermore, for example, a plurality of indoor heat exchangers 222 may be provided in parallel to one another on the pipe 278 and the pipe 271. In this case, an indoor expansion mechanism 221 may be provided on the inlet side of each of the indoor heat exchangers 222. In this case, the refrigeration device 201 includes a plurality of indoor units 220. Furthermore, in this case, one or more indoor heat exchangers 222 and one or more cooling heat exchangers 231 may be provided in parallel to one another on the pipe 278 and the pipe 271.

[0198] A plurality of chilled-use heat exchangers 231 may be provided in parallel to one another on the pipe 277 and the pipe 272. In this case, a chilled-use inlet-side expansion mechanism 232 may be provided on the inlet side of each chilled-use heat exchanger 231. In this case, at least one of the chilled-use heat exchangers 231 provided in parallel on the pipe 277 and the pipe 272 may have an evaporation temperature range different from that of the other chilled-use heat exchangers 231.

[0199] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0200] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0201] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0202] (Technology 1) A refrigeration circuit is provided which connects a plurality of compressors, a heat source side heat exchanger, a gas-liquid separator, and a plurality of user side heat exchangers, and a controller which controls the plurality of compressors, wherein the plurality of compressors include a low stage compressor and a high stage compressor, and the plurality of user side heat exchangers include a first user side heat exchanger and a second user side heat exchanger having a refrigerant evaporation temperature lower than that of the first user side heat exchanger, and the first user side heat exchanger is connected to the high stage compressor, and the second user side heat exchanger is connected to the low stage compressor. a refrigeration system including a low-stage compressor and a high-stage compressor connected to a first refrigerant pipe, the refrigeration circuit having a first service valve in a first refrigerant pipe connected to a medium-pressure pipe between the low-stage compressor and the high-stage compressor, the first service valve having an external connection port for receiving a refrigerant supply from an external source, and the controller being capable of executing a first refrigerant charging mode in which the high-stage compressor is operated with the low-stage compressor stopped, thereby charging the refrigeration circuit with refrigerant supplied from the first service valve. This stops the low-stage compressor while refrigerant is being charged from the first service valve, making it easier to maintain an appropriate pressure difference, thereby reducing the load on the compressor during refrigerant charging.

[0203] (Technology 2) The refrigeration apparatus according to Technology 1, characterized in that the first refrigerant pipe is opened and closed by a first opening / closing unit provided on the opposite side of the external connection port from the medium-pressure pipe, and the controller closes the first opening / closing unit in the first refrigerant charging mode. This stops the low-stage compressor while refrigerant is being charged through the first service valve, making it easier to maintain an appropriate pressure difference. This reduces the load on the compressor during refrigerant charging.

[0204] (Technology 3) The refrigeration apparatus according to Technology 1 or 2, characterized in that the first refrigerant pipe connects the gas-liquid separator and the medium-pressure pipe and is opened and closed by a second opening / closing unit provided on the medium-pressure pipe side relative to the external connection port, and the controller is capable of executing a refrigerant charging initial mode in the refrigerant charging mode, in which, with the second opening / closing unit closed, all of the compressors are stopped, multiple valves provided in the refrigeration circuit are closed, and the refrigerant flow path in the refrigeration circuit is separated between the gas-liquid separator and all of the compressors, thereby charging the gas-liquid separator with refrigerant supplied from the first service valve. This allows refrigerant to be charged into the refrigeration circuit without operating any of the compressors, thereby reducing the load on each compressor during refrigerant charging.

[0205] (Technology 4) The refrigeration apparatus according to Technology 3, characterized in that the controller executes the first refrigerant charging mode after executing the initial refrigerant charging mode. This allows refrigerant to be charged in the initial refrigerant charging mode without operating the high-stage compressor, and then the high-stage compressor is operated to charge refrigerant. This makes it easier to maintain an appropriate pressure difference, reducing the load on the compressor during refrigerant charging.

[0206] (Technology 5) The refrigeration system according to any one of Technologies 2 to 4, characterized in that a second service valve is provided in the low-pressure piping connected to the suction port of the low-stage compressor, and the controller can execute a second refrigerant charging mode after the first refrigerant charging mode, in which the high-stage compressor and the low-stage compressor are operated with the first opening / closing unit open, thereby charging the refrigeration circuit with refrigerant supplied from the second service valve. This allows refrigerant to be charged via the low-pressure piping connected to the low-stage compressor even when the remaining amount of refrigerant in the refrigerant tank is low. This makes it easy to charge the refrigerant to the appropriate amount.

[0207] (Technology 6) The refrigeration device according to any one of Technologies 1 to 5, wherein the controller terminates the refrigerant charging mode when the rate of change of pressure in the refrigeration circuit falls below a predetermined rate of change. This allows the controller to terminate the refrigerant charging mode when it becomes difficult to charge the refrigerant into the refrigeration circuit. This makes it easier to charge the refrigerant to an appropriate amount.

[0208] (Technology 7) The refrigeration system according to Technology 5, further comprising a notification unit, wherein the controller, upon completion of the first refrigerant charging mode, causes the notification unit to issue a notification instructing the user to reconnect an external refrigerant supply device connected to the first service valve to the second service valve. This makes it easier to charge refrigerant through a low-pressure pipe connected to a low-stage compressor even when the refrigerant tank is low in quantity. This makes it easier to charge the refrigerant to the appropriate amount.

[0209] (Technology 8) The refrigeration system according to any one of Technologies 1 to 7, further comprising a storage unit that stores a set temperature of the device having the second use-side heat exchanger, and the controller is capable of executing a manual mode in which the compressor operated in the refrigerant charging mode is fixed to a frequency specified by an input operation to an input unit, and an automatic mode in which the compressor is fixed to a frequency corresponding to a cooling load calculated from an outside air temperature and the set temperature. This allows the operating frequency of the compressor in the refrigerant charging mode to be fixed, making it easier to determine whether the refrigerant charge amount is appropriate. This makes it easier to charge the refrigerant to the appropriate amount.

[0210] (Technology 9) The refrigeration system according to Technology 1, wherein the first refrigerant pipe connects the medium-pressure pipe and the outlet side of the first user-side heat exchanger, and the first service valve can open and close the medium-pressure pipe side of the first refrigerant pipe relative to the external connection port. This allows the first service valve to be used not only when charging refrigerant but also when attaching and detaching the first user-side heat exchanger during maintenance, equipment replacement, etc. This reduces the number of parts in the refrigeration system.

[0211] (Technology 10) The refrigeration device according to any one of Technologies 1 to 9, wherein the refrigeration circuit is filled with carbon dioxide as a refrigerant. This allows carbon dioxide, which is a refrigerant with a particularly high pressure when filled, to be filled into the refrigeration circuit without placing a large load on the compressor.

[0212] (Technology 11) A refrigeration system including a refrigeration circuit connecting multiple compressors, a heat source-side heat exchanger, a gas-liquid separator, and a user-side heat exchanger, wherein the multiple compressors are configured as low-stage compressors and high-stage compressors, and a throttling mechanism is provided between the gas-liquid separator, the heat source-side heat exchanger, and the user-side heat exchanger, with a first service valve disposed upstream of the throttling mechanism and a second service valve disposed downstream of the throttling mechanism. With this configuration, the refrigeration system shares the first service valve and the second service valve as a connection portion for multiple types of external equipment with different uses. Therefore, the refrigeration system can suppress an increase in the number of parts related to connecting external equipment and simplify the structure of the refrigeration system.

[0213] (Technology 12) The refrigeration apparatus according to Technology 11, wherein the first service valve and the second service valve each have three connection ports, including an external connection port to which an external device can be connected, and the refrigeration apparatus has a configuration in which the external connection port is blocked and the remaining two connection ports are connected, a configuration in which all three connection ports are connected, and a configuration in which the external connection port is connected to one of the remaining two connection ports. With this configuration, when a specific external device is connected to a refrigeration circuit provided in the refrigeration apparatus, the refrigeration apparatus can flow a refrigerant between the refrigeration apparatus and the external device. Therefore, the refrigeration apparatus can change the refrigerant flow path depending on whether or not an external device is connected.

[0214] (Technology 13) The refrigeration apparatus according to Technology 12, wherein the first service valve is configured to communicate with the external connection port and one of the remaining two connection ports connected to the throttle mechanism, and the second service valve is configured to communicate with the external connection port and one of the remaining two connection ports connected to the gas-liquid separator. With this configuration, when a specific external device is connected to a refrigeration circuit included in the refrigeration apparatus, the refrigeration apparatus can flow refrigerant between the refrigeration apparatus and the external device. Therefore, the refrigeration apparatus can change the refrigerant flow path depending on whether or not an external device is connected.

[0215] (Technology 14) The refrigeration apparatus according to Technology 12 or Technology 13, wherein a humidity control unit can be retrofitted as the external device between the external connection port of the first service valve and the external connection port of the second service valve. With this configuration, the humidity control unit can be installed in any location in the room where dehumidification is desired. Therefore, the refrigeration apparatus can suppress condensation in the conditioned space or in the location where the cooling equipment is installed.

[0216] (Technology 15) The refrigeration apparatus according to any one of Technology 12 to Technology 14, wherein a refrigerant recovery unit can be retrofitted as the external device to at least one of the external connection ports of the first service valve and the second service valve. With this configuration, the refrigeration apparatus can share the first service valve and the second service valve with other external devices as connections for the refrigerant recovery unit. Therefore, the refrigeration apparatus can suppress an increase in the number of parts related to the connection of the refrigerant recovery unit, and the structure of the refrigeration apparatus can be simplified.

[0217] (Technology 16) The refrigeration apparatus according to any one of Technology 12 to Technology 15, wherein a coupling capable of connecting a plurality of external devices can be retrofitted to at least one of the external connection ports of the first service valve and the second service valve. With this configuration, the refrigeration apparatus can share the first service valve and the second service valve as a connection portion for a refrigerant recovery unit with a plurality of other external devices. Therefore, in the refrigeration apparatus, an increase in the number of parts related to the connection of the refrigerant recovery unit can be suppressed, and the structure of the refrigeration apparatus can be simplified.

[0218] (Technology 17) The refrigeration system according to any one of Techniques 11 to 16, including a plurality of user-side heat exchangers, the plurality of user-side heat exchangers including a first user-side heat exchanger and a second user-side heat exchanger having a refrigerant evaporation temperature lower than that of the first user-side heat exchanger. With this configuration, in a refrigeration system including a plurality of user-side heat exchangers, the first service valve and the second service valve are shared as connection portions for a plurality of types of external equipment with different uses. Therefore, in the refrigeration system, an increase in the number of parts related to connection to external equipment can be suppressed, and the structure of the refrigeration system can be simplified.

[0219] The present disclosure is applicable to refrigeration devices, specifically to refrigeration devices installed in stores such as convenience stores and supermarkets to provide air conditioning and cooling.

[0220] REFRIGERATION SYSTEM 10 OUTDOOR UNIT 11 LOW-STAGE COMPRESSOR (COMPRESSOR) 12 HIGH-STAGE COMPRESSOR (COMPRESSOR) 13 ACCUMULATOR 14 OIL SEPARATOR 15 OUTDOOR HEAT EXCHANGER 16 GAS-LIQUID SEPARATOR 17 THROTTLE MECHANISM 20 INDOOR UNIT 21 INDOOR EXPANSION MECHANISM 22 INDOOR HEAT EXCHANGER (FIRST USE-SIDE HEAT EXCHANGER) 23 ON / OFF VALVE 30 COOLING EQUIPMENT 31 COOLING HEAT EXCHANGER (SECOND USE-SIDE HEAT EXCHANGER) 32 COOLING INLET-SIDE EXPANSION MECHANISM 33 COOLING OUTLET-SIDE PRESSURE ADJUSTMENT MECHANISM 40 PIPING 41 FIRST HEATING PIPING 42 FIRST OUTDOOR RETURN PIPING 50 FIRST SWITCHING MECHANISM 51 FIRST COOLING VALVE 52 FIRST HEATING VALVE 53 OUTDOOR REFRIGERANTE RETURN VALVE 54 SECOND SWITCHING MECHANISM 55 SECOND COOLING VALVE 56 Third cooling valve 57 Second heating valve 58 Refrigerant return expansion mechanism 59 Check valve 60 Gas refrigerant return piping (first refrigerant piping) 61 Gas refrigerant flow control valve (first opening / closing unit) 71 Pipe (first refrigerant piping) 72 Pipe (low pressure piping) 73 First pipe 74 Second pipe 75 Third pipe 76 Fourth pipe 77 Pipe 78 Pipe 79 Pipe 80 Medium pressure piping 95 Outdoor unit I / F 101 Refrigeration device 201 Refrigeration device 210 Outdoor unit 211 Low stage compressor 212 High stage compressor 213 Accumulator 214 Oil separator 215 Outdoor heat exchanger 216 Gas-liquid separator 217 Throttle mechanism 220 Indoor unit 221 Indoor expansion mechanism 222 Indoor heat exchanger 230 Refrigeration equipment 231 Refrigeration heat exchanger 250 First switching mechanism 254 Second switching mechanism 260 Gas refrigerant return pipe 261 Gas refrigerant flow control valve 301 First service valve 302 Second service valve 305 External equipment 390 External connection port 401 First service valve 402 Second service valve 500A External connection port 500B External connection port 501A First connection port 501B First connection port 502A Second connection port 502B Second connection port 601 Low pressure side pressure sensor 602 Intermediate pressure side pressure sensor 603 High pressure side pressure sensor 604 Second intermediate pressure side pressure sensor 700 Controller 701 Control unit 703 Storage unit705 Mode information 707 Switching information 709 Setting information 801 Notification section 803 Input section A Connection section B Connection section C Connection section D Connection section

Claims

1. A refrigeration circuit connecting a plurality of compressors, a heat source side heat exchanger, a gas-liquid separator, and a plurality of user side heat exchangers, and a controller controlling the plurality of compressors, wherein the plurality of compressors include a low stage compressor and a high stage compressor, and the plurality of user side heat exchangers include a first user side heat exchanger and a second user side heat exchanger having a refrigerant evaporation temperature lower than that of the first user side heat exchanger, wherein the first user side heat exchanger is connected to the high stage compressor, and the second user side heat exchanger is connected to the low stage compressor, the refrigeration circuit has a first service valve on a first refrigerant piping connected to a medium pressure piping between the low stage compressor and the high stage compressor, and the first service valve has an external connection port for receiving a supply of refrigerant from the outside, the controller is capable of executing a first refrigerant charging mode in which the refrigeration circuit is filled with refrigerant supplied from the first service valve by operating the high stage compressor while stopping the low stage compressor, as a refrigerant charging mode.

2. The refrigeration device described in claim 1, characterized in that the first refrigerant piping is opened and closed by a first opening and closing unit provided on the opposite side of the medium pressure piping with respect to the external connection port, and the controller closes the first opening and closing unit in the first refrigerant charging mode.

3. The refrigeration device described in claim 1, characterized in that the first refrigerant piping is a piping connecting the gas-liquid separator and the medium pressure piping, and is opened and closed by a second opening and closing unit provided on the side of the medium pressure piping with the external connection port as a reference, and the controller is capable of executing, as the refrigerant charging mode, an initial refrigerant charging mode in which, with the second opening and closing unit closed, all of the compressors are stopped, a plurality of valves provided in the refrigeration circuit are closed, and the refrigerant flow path in the refrigeration circuit is separated between the gas-liquid separator and all of the compressors, thereby filling the gas-liquid separator with refrigerant supplied from the first service valve.

4. The refrigeration system according to claim 3, wherein the controller executes the first refrigerant charging mode after the initial refrigerant charging mode is executed.

5. The refrigeration system according to claim 2, characterized in that a second service valve is provided in a low-pressure piping connected to the suction port of the low-stage compressor, and the controller is capable of executing a second refrigerant charging mode in which refrigerant supplied from the second service valve is charged into the refrigeration circuit by operating the high-stage compressor and the low-stage compressor with the first opening / closing unit open as the refrigerant charging mode after the first refrigerant charging mode.

6. The refrigeration device according to claim 1, wherein the controller terminates execution of the refrigerant charging mode in progress when a rate of change of pressure in the refrigeration circuit falls below a predetermined rate of change.

7. The refrigeration device as described in claim 5, further comprising a notification unit, wherein the controller causes the notification unit to execute a notification instructing the user to reconnect an external refrigerant supply device connected to the first service valve to the second service valve when the first refrigerant charging mode ends.

8. A refrigeration device as described in claim 6, further comprising a memory unit which stores a set temperature of a device having the second utilization side heat exchanger, and the controller is capable of executing a manual mode in which the compressor operated in the refrigerant charging mode during execution is operated at a fixed frequency specified by an input operation to an input unit, and an automatic mode in which the compressor is operated at a fixed frequency corresponding to a cooling load calculated from an outside air temperature and the set temperature.

9. The refrigeration system described in claim 1, characterized in that the first refrigerant piping connects the medium pressure piping and an outlet side of the first user side heat exchanger, and the first service valve is capable of opening and closing the side of the first refrigerant piping that is the medium pressure piping based on the external connection port.

10. The refrigeration device according to any one of claims 1 to 5, wherein the refrigeration circuit is filled with carbon dioxide as a refrigerant.

11. A refrigeration system comprising a refrigeration circuit connecting a plurality of compressors, a heat source side heat exchanger, a gas-liquid separator, and a utilization side heat exchanger, wherein the plurality of compressors are composed of a low stage compressor and a high stage compressor, and a throttling mechanism is provided between the gas-liquid separator, the heat source side heat exchanger, and the utilization side heat exchanger, a first service valve is disposed upstream of the throttling mechanism, and a second service valve is disposed downstream of the throttling mechanism.

12. The refrigeration apparatus of claim 11, wherein the first service valve and the second service valve each have three connection ports including an external connection port capable of connecting an external device, and are provided with: a configuration in which the external connection port is blocked and the remaining two connection ports are connected; a configuration in which all three connection ports are connected; and a configuration in which the external connection port is connected to one of the remaining two connection ports.

13. A refrigeration system as described in claim 12, wherein the first service valve is configured to communicate between the external connection port and one of the two remaining connection ports that is connected to the throttling mechanism, and the second service valve is configured to communicate between the external connection port and one of the two remaining connection ports that is connected to the gas-liquid separator.

14. A refrigeration system as described in claim 12 or 13, wherein a humidity control unit can be retrofitted as the external device between the external connection port of the first service valve and the external connection port of the second service valve.

15. A refrigeration system as described in claim 12 or 13, wherein a refrigerant recovery unit can be retrofitted as the external device to at least one of the external connection port of the first service valve and the external connection port of the second service valve.

16. A refrigeration system as described in claim 12 or 13, wherein a fitting capable of connecting a plurality of external devices can be retrofitted to at least one of the external connection port of the first service valve and the external connection port of the second service valve.

17. A refrigeration system as described in any one of claims 11 to 13, comprising a plurality of user-side heat exchangers, the plurality of user-side heat exchangers being composed of a first user-side heat exchanger and a second user-side heat exchanger having a refrigerant evaporation temperature lower than that of the first user-side heat exchanger.

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