REFRIGERANT LEAKAGE DETERMINATION METHOD AND REFRIGERATION CYCLE APPARATUS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of international application no. PCT/JP2023/045715, filed Dec. 20, 2023, which claims priority to Japanese patent application JP 2022-208822, filed Dec. 26, 2022, the entire contents of each are incorporated herein by reference.

TECHNICAL FIELD

Embodiments relate to a refrigerant leakage determination method and a refrigeration cycle apparatus.

BACKGROUND ART

Patent Literature 1 (WO 2015/004747 A) discloses a refrigeration cycle apparatus including a refrigerant circuit configured to circulate a refrigerant through a compressor, a condenser, an expansion valve, and an evaporator, the compressor and the condenser being connected by a first extension pipe, and the expansion valve and the evaporator being connected by a second extension pipe, a detector that detects an operation state amount of the refrigerant circuit, and a control unit that performs a refrigerant leakage detection operation by calculating a refrigerant amount inside the refrigerant circuit on the basis of the operation state amount detected by the detector and performing refrigerant leakage detection by comparing the calculated refrigerant amount with a reference refrigerant amount, in which the control unit controls a dryness of the refrigerant at an outlet of the second extension pipe to be 0.1 or more and 0.7 or less during the refrigerant leakage detection operation.

SUMMARY

A refrigerant leakage determination method according to a first aspect includes the following steps. A refrigerant circuit formed by connecting a heat source unit and a utilization unit by a connection pipe is filled with a refrigerant of a first filling amount smaller than a target filling amount. A first trial operation of circulating the refrigerant of the first filling amount in the refrigerant circuit is performed, and first trial operation data is acquired. After the step of acquiring, the refrigerant circuit is filled with the refrigerant until the target filling amount is reached. Normal operation data is acquired during a normal operation after filling the refrigerant circuit with the target filling amount. The presence or absence of a refrigerant leakage from the refrigerant circuit is determined on the basis of the normal operation data and the first trial operation data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration of a management system according to an embodiment of the present disclosure.

FIG. 2 is a diagram showing a functional block configuration of a refrigeration cycle apparatus according to an embodiment of the present disclosure.

FIG. 3 is a schematic configuration diagram of the refrigeration cycle apparatus according to the embodiment.

FIG. 4 is a flowchart showing a refrigerant leakage determination method according to the embodiment.

FIG. 5 is a flowchart showing a refrigerant leakage determination method according to a modification.

DESCRIPTION OF EMBODIMENTS

(1) Overall Configuration of Management System of Refrigeration Cycle Apparatus

As shown in FIG. 1, a management system 100 of a refrigeration cycle apparatus 1 is a device for managing the refrigeration cycle apparatus 1. The management system 100 of the refrigeration cycle apparatus 1 is a system that determines presence or absence of a refrigerant leakage from the refrigeration cycle apparatus 1 and notifies a user when it is determined that there is a refrigerant leakage. The user includes a person who uses the refrigeration cycle apparatus 1 and a person who manages the refrigeration cycle apparatus 1.

The management system 100 includes the refrigeration cycle apparatus 1, a server 40, and an information device 50. The server 40 is connected to the refrigeration cycle apparatus 1. The information device 50 is connected to the server 40. A description will be given of each configuration included in the management system 100.

(2) Refrigeration Cycle Apparatus

The refrigeration cycle apparatus 1 is an apparatus that processes a thermal load of a target space by performing a vapor compression refrigeration cycle, and is, for example, an air conditioner that conditions air in the target space. As shown in FIGS. 2 and 3, the refrigeration cycle apparatus 1 includes one heat source unit 20 (i.e., heat source), a plurality of utilization units 30 (i.e., heat utilizer), connection pipes 5 and 6 connecting heat source unit 20 and the plurality of utilization units 30, and a remote controller 36. In the present embodiment, the heat source unit 20 and the utilization unit 30 are communicably connected via a transmission line 97 shown in FIG. 2.

A vapor compression refrigerant circuit 10 of the refrigeration cycle apparatus 1 is configured by connecting the heat source unit 20 and the utilization unit 30 via the connection pipes 5 and 6. The refrigerant circuit 10 is filled with a refrigerant for a vapor compression refrigeration cycle. The refrigerant to fill the refrigerant circuit 10 is not limited, and for example, the refrigerant circuit 10 is filled with R32 or the like. The refrigerant circuit 10 is filled with refrigerating machine oil in together with the refrigerant.

(2-1) Heat Source Unit

As shown in FIG. 3, the heat source unit 20 is connected to the utilization unit 30 via the connection pipes 5 and 6, and constitutes a part of the refrigerant circuit 10. The heat source unit 20 mainly includes a compressor 21, a four-way switching valve 22, a first heat exchanger 23, a first expansion valve 24, a first fan 25, a receiver 26, a gas-side shutoff valve 28, a liquid-side shutoff valve 29, and first to seventh refrigerant pipes 11 to 17.

The compressor 21 is a device that compresses a low-pressure refrigerant in the refrigeration cycle to a high pressure. The compressor 21 used herein can be a closed compressor in which a rotary type, scroll type, or other positive-displacement compression element is driven to rotate by a compressor motor. The compressor motor is for changing a capacity, and an operating frequency can be controlled by an inverter. The seventh refrigerant pipe 17 as a suction pipe is connected to a suction side of the compressor 21. The first refrigerant pipe 11 as a discharge pipe is connected to a discharge side of the compressor 21.

The four-way switching valve 22 is a valve whose flow path is switched by movement control of a valve body (not shown), and switches the refrigerant circuit 10 between a cooling connection state and a heating connection state. Specifically, in the cooling connection state, the four-way switching valve 22 is switched to a state of connecting the first refrigerant pipe 11 connected to the discharge side of the compressor 21 and the second refrigerant pipe 12 connected to the first heat exchanger 23 while connecting the seventh refrigerant pipe 17, the receiver 26, the sixth refrigerant pipe 16 connected to the suction side of the compressor 21 and the fifth refrigerant pipe 15 connected to the gas-side shutoff valve 28. In the heating connection state, the four-way switching valve 22 is switched to a state of connecting the first refrigerant pipe 11 connected to the discharge side of the compressor 21 and the fifth refrigerant pipe 15 connected to the gas-side shutoff valve 28 while connecting the seventh refrigerant pipe 17, the receiver 26, the sixth refrigerant pipe 16 connected to the suction side of the compressor 21 and the second refrigerant pipe 12 connected to the first heat exchanger 23.

The first heat exchanger 23 functions as a condenser for the high-pressure refrigerant in the refrigeration cycle during a cooling operation, and functions as an evaporator for the low-pressure refrigerant in the refrigeration cycle during a heating operation. A gas-side end of the first heat exchanger 23 is connected to the four-way switching valve 22 via the second refrigerant pipe 12. A liquid-side end of the first heat exchanger 23 is connected to the first expansion valve 24 via the third refrigerant pipe 13.

The first expansion valve 24 is provided between a liquid-side outlet of the first heat exchanger 23 and the liquid-side shutoff valve 29 in the refrigerant circuit 10. The first expansion valve 24 is an electric expansion valve having an adjustable valve opening degree by movement control of a valve body (not shown) with respect to a valve seat (not shown). The first expansion valve 24 and the liquid-side shutoff valve 29 are connected via the fourth refrigerant pipe 14.

The first fan 25 sucks outdoor air into the heat source unit 20, causes the first heat exchanger 23 to exchange heat with the refrigerant, and then generates an air flow to be discharged to the outside. The first fan 25 is driven to rotate by a fan motor.

The receiver 26 is provided between the suction side of the compressor 21 and one of connecting ports of the four-way switching valve 22, and is a refrigerant container capable of storing surplus refrigerant in the refrigerant circuit 10 as liquid refrigerant. An inlet side of the receiver 26 is connected to the four-way switching valve 22 via the sixth refrigerant pipe 16. An outlet side of the receiver 26 is connected to the suction side of the compressor 21 via the seventh refrigerant pipe 17.

The liquid-side shutoff valve 29 is a manual valve disposed at a connecting portion of the heat source unit 20 with the liquid-side connection pipe 6. The gas-side shutoff valve 28 is a manual valve disposed at a connecting portion of the heat source unit 20 with the gas-side connection pipe 5.

The heat source unit 20 is provided with a discharge pressure sensor 61, a discharge temperature sensor 62, a suction pressure sensor 63, a suction temperature sensor 64, a liquid-side temperature sensor 65, an outside air temperature sensor 66, and the like. The discharge pressure sensor 61 detects the pressure of the refrigerant flowing through the first refrigerant pipe 11, which is a discharge pipe connecting the discharge side of the compressor 21 and one of the connecting ports of the four-way switching valve 22. The discharge temperature sensor 62 detects the temperature of the refrigerant flowing through the first refrigerant pipe 11 as a discharge pipe. The suction pressure sensor 63 detects the pressure of the refrigerant flowing through the seventh refrigerant pipe 17, which is a suction pipe connecting the suction side of the compressor 21 and the receiver 26. The suction temperature sensor 64 detects the temperature of the refrigerant flowing through seventh refrigerant pipe 17 as a suction pipe. The liquid-side temperature sensor 65 detects the temperature of the refrigerant flowing through the liquid-side outlet of the first heat exchanger 23 opposite to the side to which the four-way switching valve 22 is connected. The outside air temperature sensor 66 detects the temperature of outdoor air before the outdoor air passes through the first heat exchanger 23. Each of these sensors is electrically connected to a first control unit 20c (i.e., first controller, described later), and transmits a detection signal to the first control unit 20c.

As shown in FIG. 2, the heat source unit 20 includes a first communication unit 20a, a first input unit 20b, the first control unit 20c, and a first storage 20d.

The first communication unit 20a is an interface for communicating with the utilization unit 30. The first communication unit 20a is also an interface for communicating with the server 40.

The first input unit 20b is a button for receiving a command to execute a first trial operation from an operator. Here, the first input unit 20b includes a button for receiving a command to execute the first trial operation and a button for receiving a command to execute a final trial operation. When the command to execute the first trial operation or the final trial operation is received by the first input unit 20b, the first trial operation or the final trial operation is executed by the first control unit 20c, and a plurality of trial operation data (described later) is detected.

The first control unit 20c is a calculation processing device such as a central processing unit (CPU). The first control unit 20c reads and executes a program stored in the first storage 20d.

The first control unit 20c controls (e.g., includes circuitry configured to control) an operation of each part constituting the heat source unit 20. The first control unit 20c can exchange a control signal with a second control unit 35 of each utilization unit 30 via the transmission line 97. Here, the first control unit 20c connected to the transmission line 97 and each of the second control units 35 cooperate to control the entire operation of the refrigeration cycle apparatus 1. In other words, the first control unit 20c controls (e.g., includes circuitry configured to control) the operation of the refrigerant circuit 10 in cooperation with the second control unit 35, e.g., the first control unit 20c and the second control unit 35 together may be a controller.

Specifically, the first control unit 20c operates each unit constituting the heat source unit 20 in accordance with a control command to start, stop, set a temperature, set a humidity, set an air volume, set an air direction, or set an operating mode of the utilization unit 30. More specifically, the first control unit 20c generates a control command for adjusting a frequency of the compressor 21, a number of rotations of the first fan 25, the opening degree of the first expansion valve 24, and the like.

Furthermore, the first control unit 20c acquires first trial operation data by performing the first trial operation of circulating the refrigerant of a first filling amount smaller than a target filling amount (100%) in the refrigerant circuit 10. The target filling amount is a required refrigerant filling amount described in an installation instruction. The target filling amount is an amount of the refrigerant circulating in the refrigerant circuit 10 when a normal operation such as the cooling operation or the heating operation is performed. The first filling amount is, for example, 50% or more and less than 100% of the target filling amount, and is set to 70% of the target filling amount in the present embodiment.

Specifically, when the first input unit 20b receives the command to execute the first trial operation, the first control unit 20c operates each unit constituting the heat source unit 20 to execute the first trial operation, and sends a command to the second control unit 35 of the utilization unit 30 to operate each part constituting the utilization unit 30. Then, the first control unit 20c acquires the first trial operation data during the first trial operation. The first trial operation data is, for example, an opening degree of the second expansion valve 33 of each utilization unit 30. Then, the first control unit 20c stores the acquired first trial operation data in the first storage 20d.

The first control unit 20c acquires final trial operation data by performing the final trial operation of circulating the refrigerant of the target filling amount in the refrigerant circuit 10. Specifically, when the first input unit 20b receives the command to execute the final trial operation, the first control unit 20c operates each unit constituting the heat source unit 20 to execute the final trial operation, and sends a command to the second control unit 35 of the utilization unit 30 to operate each part constituting the utilization unit 30. Then, the first control unit 20c acquires the final trial operation data during the final trial operation. The final trial operation data is, for example, the opening degree of the second expansion valve 33 of each utilization unit 30. Then, the acquired final trial operation data is stored in the first storage 20d.

In this manner, the first control unit 20c has a plurality of trial operation modes. In the present embodiment, the first control unit 20c has two modes, namely, the first trial operation of circulating the refrigerant of the first filling amount smaller than the target filling amount, and the final trial operation of circulating the refrigerant of the target filling amount.

Furthermore, the first control unit 20c acquires normal operation data during the normal operation after filling the refrigerant circuit 10 with the target filling amount, and determines the presence or absence of a refrigerant leakage from the refrigerant circuit 10 on the basis of the normal operation data and the first trial operation data. In the present embodiment, the first control unit 20c determines the presence or absence of a refrigerant leakage from the refrigerant circuit 10 on the basis of the normal operation data, the first trial operation data, and the final trial operation data. Here, in the normal operation, the first control unit 20c compares the normal operation data at the time when a condition similar to a condition of the first trial operation is satisfied with the first trial operation data, and when the normal operation data is similar to the first trial operation data, the first control unit 20c determines that the refrigerant has leaked from the refrigerant circuit 10.

The first trial operation data and the final trial operation data acquired by the first control unit 20c are, for example, data on the opening degree of each second expansion valve 33 at the time when all of the plurality of utilization units 30 performs the cooling operation. The first control unit 20c acquires the opening degree of each of the second expansion valves 33 as the normal operation data when all the utilization units 30 performs the cooling operation during the normal operation. The first control unit 20c compares the opening degree of each second expansion valve 33 as the first trial operation data, the opening degree of each second expansion valve 33 as the final trial operation data, and the opening degree of each second expansion valve 33 as the normal operation data. Specifically, the presence or absence of a refrigerant leakage is determined by calculating how close the opening degree of each second expansion valve 33 during the normal operation is to the opening degree of each second expansion valve 33 during the first trial operation from the opening degree of each second expansion valve 33 during the final trial operation. Note that target evaporation temperatures in the first trial operation, the final trial operation, and the normal operation are the same.

The first storage 20d includes a ROM, a RAM, a hard disk, and the like. The first storage 20d stores a program that can be read and executed by the first control unit 20c. The first storage 20d stores the first trial operation data, the final trial operation data, the normal operation data, and the like.

(2-2) Utilization Unit

The utilization unit 30 is installed on, for example, an indoor wall surface, a ceiling, or the like as the target space. The utilization unit 30 is connected to the heat source unit 20 via the connection pipes 5 and 6, and constitutes a part of the refrigerant circuit 10. In the refrigeration cycle apparatus 1 according to the present embodiment, the plurality of utilization units 30 is connected in parallel to one heat source unit 20. Since the utilization units 30 have similar configurations, one utilization unit 30 will be described below.

The utilization unit 30 includes a second heat exchanger 31, an eighth refrigerant pipe 18, a ninth refrigerant pipe 19, a second fan 32, and the second expansion valve 33.

The second heat exchanger 31 has a liquid side connected to liquid-side connection pipe 6 via the eighth refrigerant pipe 18, and a gas side end connected to the gas-side connection pipe 5 via the ninth refrigerant pipe 19. The second heat exchanger 31 functions as an evaporator for the low-pressure refrigerant in the refrigeration cycle during the cooling operation, and functions as a condenser for the high-pressure refrigerant in the refrigeration cycle during the heating operation.

The second fan 32 sucks indoor air into the utilization unit 30, causes the second heat exchanger 31 to exchange heat with the refrigerant, and then generates an air flow to be discharged to the outside. The second fan 32 is driven to rotate by a fan motor. The second fan 32 can be driven with the set air volume received from the remote controller 36.

The second expansion valve 33 is provided between a liquid-side inlet of the second heat exchanger 31 and the liquid-side connection pipe 6 in the refrigerant circuit 10. The second expansion valve 33 is an electric expansion valve having an adjustable valve opening degree by movement control of a valve body (not shown) with respect to a valve seat (not shown). The second expansion valve 33 is provided corresponding to the liquid side of the second heat exchanger 31. The second expansion valve 33 is an expansion mechanism that adjusts a flow rate of the refrigerant flowing through the second heat exchanger 31 while decompressing the refrigerant.

The utilization unit 30 is provided with a liquid-side heat exchange temperature sensor 71, an air temperature sensor 72, and the like. The liquid-side heat exchange temperature sensor 71 detects the temperature of the refrigerant flowing through a liquid-refrigerant side inlet of the second heat exchanger 31. The air temperature sensor 72 detects the temperature of indoor air before the indoor air passes through the second heat exchanger 31. Each of these sensors is electrically connected to the second control unit 35 (described later), and transmits a detection signal to the second control unit 35.

The utilization unit 30 includes a second communication unit 34 and the second control unit 35. The second communication unit 34 is an interface for communicating with the heat source unit 20.

The second control unit 35 includes a microcomputer including a processor such as a central processing unit (CPU), a memory, and the like.

The utilization unit 30 includes the second control unit 35 and the second communication unit 34 that control the operation of each part constituting the utilization unit 30. The second control unit 35 receives a control signal from the heat source unit 20 via the second communication unit 34, and operates each part constituting the utilization unit 30 on the basis of the control signal. Specifically, the second control unit 35 generates a control command for adjusting a number of rotations of the second fan 32, the opening degree of the second expansion valve 33, and the like.

The second control unit 35 transmits data on an operation state such as an ON or OFF state and a suction temperature to the heat source unit 20 via the second communication unit 34.

The remote controller 36 that receives an operation input to each utilization unit 30 is separately attached to each utilization unit 30. The remote controller 36 includes an input unit that receives a control command to each of the utilization units 30, and a display that displays an operation status of each of the utilization units 30. The operation status displayed on the display of the remote controller 36 includes information indicating an operation state such as the cooling operation, the heating operation, and an inspection, and information such as a set temperature, an air volume, and an air flow direction.

(3) Server

The server 40 shown in FIG. 1 is connected to the refrigeration cycle apparatus 1 via a communication line either in a wired or wireless manner. The server 40 has a function of monitoring and controlling the refrigeration cycle apparatus 1. The server 40 according to the present embodiment is constructed on a cloud.

When the first control unit 20c determines that there is a refrigerant leakage, the server receives a notification of the leakage from the first control unit 20c and notifies the user of the leakage. Here, when it is determined that there is a refrigerant leakage, the server 40 notifies the information device 50 of the user of the leakage. The notification is performed by issuing a warning to the user by sound, light, display, or the like.

(4) Information Device

The information device 50 is notified when the refrigeration cycle apparatus 1 determines that there is a refrigerant leakage. The type of the information device 50 is not limited, and is, for example, a smartphone, a wearable device, a personal computer, a tablet, or the like. Examples of the wearable device include a wristband-type device, a wristwatch-type device, or the like that is worn on an arm, a headband-type device, a glasses-type device, or the like that is worn on a head, and a cloth-type device, or the like that is worn on a body.

(5) Normal Operation

The refrigeration cycle apparatus 1 can execute at least a cooling operating mode and a heating operating mode as the normal operation. In the refrigeration cycle apparatus 1 according to the present embodiment, the plurality of utilization units 30 can perform the cooling operation or the heating operation individually.

In the refrigeration cycle apparatus 1, the first control unit 20c and the second control unit 35 determine whether the operation mode is the cooling operation mode or the heating operating mode on the basis of an instruction received from the remote controller 36 or the like, and execute the determined operating mode.

(5-1) Cooling Operation

The cooling operation is performed by the first control unit 20c and the second control unit 35 receiving a command of the cooling operation via the remote controller 36. The first control unit 20c and the second control unit 35 control the operations of the compressor 21, the four-way switching valve 22, the first expansion valve 24, the first fan 25, the second fan 32, the second expansion valve 33, and the like as constituent devices of the heat source unit 20 and the utilization unit 30.

In the cooling operation, the four-way switching valve 22 is switched to a state such that the first heat exchanger 23 functions as a refrigerant condenser and the second heat exchanger 31 functions as a refrigerant evaporator (as shown by the solid lines of the four-way switching valve 22 in FIG. 1).

In the refrigerant circuit 10 in such a state, the low-pressure refrigerant in the refrigeration cycle is sucked into the compressor 21, compressed to a high pressure in the refrigeration cycle, and then discharged. The high-pressure gas refrigerant discharged from the compressor 21 is sent to the first heat exchanger 23 through the four-way switching valve 22. The high-pressure refrigerant sent to the first heat exchanger 23 exchanges heat with the outdoor air supplied by the first fan 25 and condenses in the first heat exchanger 23. The high-pressure refrigerant having condensed in the first heat exchanger 23 is sent to the first expansion valve 24 and decompressed to a low pressure in the refrigeration cycle. The low-pressure refrigerant decompressed in the first expansion valve 24 flows out of the heat source unit 20 and is branched and sent to each utilization unit 30 through the liquid-side connection pipe 6. The refrigerant sent to the utilization unit 30 is decompressed to a low pressure in the refrigeration cycle by the second expansion valve 33 and sent to the second heat exchanger 31. The low-pressure refrigerant sent to the second heat exchanger 31 exchanges heat with the indoor air supplied by the second fan 32 in the second heat exchanger 31 and evaporates. As a result, the indoor air is cooled and blown to indoor. The low-pressure refrigerant having evaporated in the second heat exchanger 31 is again sucked into the compressor 21 through the gas-side connection pipe 5, the four-way switching valve 22, and the receiver 26. In this manner, in the cooling operation, the first control unit 20c and the second control unit 35 perform an operation of circulating the refrigerant sealed in the refrigerant circuit 10 through the compressor 21, the first heat exchanger 23, the first expansion valve 24, the second expansion valve 33, and the second heat exchanger 31 in that order.

During the cooling operation, the first control unit 20c and the second control unit 35 perform capacity control to control the capacity of the compressor 21 such that an evaporation temperature of the refrigerant in the refrigerant circuit 10 approaches a predetermined target evaporation temperature. The capacity control of the compressor 21 is performed by controlling the number of rotations (frequency) of the compressor motor. The evaporation temperature of the refrigerant is obtained by converting the suction pressure detected by the suction pressure sensor 63 into a saturation temperature of the refrigerant. The refrigerant evaporation temperature is a temperature obtained by converting the pressure (evaporation pressure of the refrigerant in the refrigerant circuit 10) representing the low-pressure refrigerant in the refrigeration cycle flowing from an exit of the second expansion valve 33 to the suction side of the compressor 21 via the second heat exchanger 31 into a saturation temperature of the refrigerant during the cooling operation, or a saturation temperature of the refrigerant in the second heat exchanger 31 functioning as an evaporator of the refrigerant. Thus, when the second heat exchanger 31 is provided with a temperature sensor, the temperature of the refrigerant detected by the temperature sensor may be the evaporation temperature of the refrigerant.

(5-2) Heating Operation

The heating operation is performed by the first control unit 20c and the second control unit 35 receiving a command of the heating operation via the remote controller 36. The first control unit 20c and the second control unit 35 control the operations of the compressor 21, the four-way switching valve 22, the first expansion valve 24, the first fan 25, the second fan 32, the second expansion valve 33, and the like as constituent devices of the heat source unit 20 and the utilization unit 30.

In the heating operation, the four-way switching valve 22 is switched to a state such that the first heat exchanger 23 functions as a refrigerant evaporator and the second heat exchanger 31 functions as a refrigerant condenser (as shown by the broken lines of the four-way switching valve 22 in FIG. 1).

In the refrigerant circuit 10 in such a state, the low-pressure refrigerant in the refrigeration cycle is sucked into the compressor 21, compressed to a high pressure in the refrigeration cycle, and then discharged. The high-pressure refrigerant discharged from the compressor 21 is sent to the second heat exchanger 31 through the four-way switching valve 22 and the gas-side connection pipe 5. The high-pressure refrigerant sent to the second heat exchanger 31 exchanges heat with the indoor air supplied by the second fan 32 and condenses in the second heat exchanger 31. As a result, the indoor air is heated and blown to indoor. The high-pressure refrigerant having condensed in the second heat exchanger 31 is decompressed by the second expansion valve 33 and flows out of the utilization unit 30. The refrigerant flowing out of the utilization unit 30 is sent to the first expansion valve 24 through the liquid-side connection pipe 6, and decompressed to a low pressure in the refrigeration cycle. The low-pressure refrigerant decompressed in the first expansion valve 24 is sent to the first heat exchanger 23. The low-pressure refrigerant sent to the first heat exchanger 23 exchanges heat with outdoor air supplied by the first fan 25 in the first heat exchanger 23 and evaporates. The low-pressure refrigerant having evaporated in the first heat exchanger 23 is sucked into the compressor 21 again through the four-way switching valve 22 and the receiver 26. In this manner, in the heating operation, the first control unit 20c and the second control unit 35 perform an operation of circulating the refrigerant sealed in the refrigerant circuit 10 through the compressor 21, the second heat exchanger 31, the second expansion valve 33, the first expansion valve 24 and the first heat exchanger 23 in that order.

In the heating operation, the first control unit 20c and the second control unit 35 perform capacity control to control the capacity of the compressor 21 such that a condensation temperature of the refrigerant in the refrigerant circuit 10 approaches a predetermined target condensation temperature. The capacity control of the compressor 21 is performed by controlling the number of rotations (frequency) of the compressor motor. The condensation temperature of the refrigerant is obtained by converting the discharge pressure detected by the discharge pressure sensor 61 into a saturation temperature of the refrigerant. The condensation temperature of the refrigerant is a temperature obtained by converting a pressure (a condensation pressure of the refrigerant in the refrigerant circuit 10) representing the high-pressure refrigerant flowing from the discharge side of the compressor 21 into the first expansion valve 24 via the second heat exchanger 31 into a saturation temperature of the refrigerant during the heating operation, or a saturation temperature of the refrigerant in the second heat exchanger 31 functioning as a condenser of the refrigerant. Thus, when the second heat exchanger 31 is provided with a temperature sensor, the temperature of the refrigerant detected by the temperature sensor may be the condensation temperature of the refrigerant.

(6) Refrigerant Leakage Determination Method

Next, a refrigerant leakage determination method according to the present embodiment will be described.

During construction of the refrigeration cycle apparatus 1, first, as shown in FIGS. 3 and 4, the refrigerant circuit 10 formed by connecting the heat source unit 20 and the utilization unit 30 by the connection pipes 5 and 6 is filled with the refrigerant of the first filling amount smaller than the target filling amount (step S1). This step (S1) is executed, for example, as follows.

Specifically, the heat source unit 20 filled with the refrigerant of the first filling amount or less is prepared as an initial filling amount. Here, the heat source unit 20 filled with the refrigerant of the initial filling amount which is smaller than the first filling amount, for example, 50% of the target filling amount is prepared. The heat source unit 20 is connected to the plurality of utilization units 30 by the liquid-side connection pipe 6 and the gas-side connection pipe 5. In this manner, the refrigerant circuit 10 filled with the refrigerant of the initial filling amount can be formed. Thereafter, the refrigerant circuit 10 is filled with the refrigerant so as to reach a first refrigerant amount. Here, by additionally filling the refrigerant circuit 10 with the refrigerant of 20% of the target filling amount, the refrigerant circuit 10 is filled with the refrigerant of 70% of the target filling amount as the first filling amount.

The method for additionally filling the refrigerant circuit 10 the refrigerant is not limited, but is performed manually as follows, for example. The container filled with the refrigerant to be added is connected to a charge port of the heat source unit 20. Here, the charge port is provided in the gas-side shutoff valve 28 or the liquid-side shutoff valve 29. Thereafter, the operator opens a refrigerant supply valve of the container and the charge port. The compressor 21 is driven to circulate the refrigerant in the heat source unit 20 in the same manner as in the cooling operation or the heating operation. Thus, the refrigerant in the container flows into the refrigerant circuit 10 via the charge port. Here, the refrigerant flowing into the refrigerant circuit 10 via the charge port is sucked into the compressor 21 through the receiver 26. When a total of the initial filling amount and an additional filling amount of the refrigerant filled in the refrigerant circuit 10 reaches the first filling amount, the operator closes the refrigerant supply valve of the container and the charge port. The additional filling amount is calculated in advance in consideration of the lengths of the connection pipes 5 and 6, the number of the utilization units 30, and the like, and the refrigerant circuit 10 is filled with the refrigerant while measuring the weight of the container.

Next, the first trial operation of circulating the refrigerant of the first filling amount in the refrigerant circuit 10 is performed, and first trial operation data is acquired (step S2). This step (S2) is executed, for example, as follows.

Specifically, when the first input unit 20b receives a command to execute the first trial operation, the first control unit 20c operates each part constituting the refrigeration cycle apparatus 1 in cooperation with the second control unit 35, and circulates the refrigerant of the first filling amount in the refrigerant circuit 10 such that all the utilization units 30 performs the cooling operation or the heating operation. When the first trial operation is the cooling operation, the first control unit 20c performs capacity control to control the capacity of the compressor 21 such that the evaporation temperature of the refrigerant in the refrigerant circuit approaches a predetermined target evaporation temperature. The target evaporation temperature in the first trial operation is the same as the target evaporation temperature at the time when the normal operation is the cooling operation. When the first trial operation is the heating operation, the first control unit 20c performs capacity control to control the capacity of the compressor 21 such that the condensation temperature of the refrigerant in the refrigerant circuit 10 approaches a predetermined target condensation temperature. The target condensation temperature in the first trial operation is the same as a target condensation temperature at the time when the normal operation is the heating operation. When the state of the refrigerant in the refrigerant circuit 10 is stabilized, the opening degree of the second expansion valve 33 of each of the utilization units 30 at the time when the refrigerant of the first filling amount is circulated is acquired as the first trial operation data. When the first trial operation data is acquired, the compressor 21 is stopped. The first control unit 20c stores the first trial operation data in the first storage 20d.

Next, the refrigerant circuit 10 is filled with the refrigerant until the target filling amount is reached (step S3). This step (S3) is executed, for example, as follows.

Specifically, the refrigerant circuit 10 having been filled with the refrigerant of the first filling amount is filled with the refrigerant of the difference between the target filling amount and the first filling amount. Here, by additionally filling the refrigerant circuit 10 with the refrigerant of 30% of the target filling amount, the refrigerant circuit 10 is filled with the refrigerant of the target filling amount (100%). The method of additionally filling the refrigerant circuit 10 with the refrigerant is similar to the step (S1) of filling the refrigerant circuit 10 with the refrigerant of the first filling amount.

Next, the final trial operation of circulating the refrigerant of the target filling amount in the refrigerant circuit 10 is performed, and the final trial operation data is acquired (step S4). This step (S4) is executed, for example, as follows.

Specifically, when the first input unit 20b receives a command to execute the final trial operation, the first control unit 20c operates each part constituting the refrigeration cycle apparatus 1 in cooperation with the second control unit 35, and circulates the refrigerant of the target filling amount in the refrigerant circuit 10 such that all the utilization units 30 performs the cooling operation or the heating operation. When the first trial operation is the cooling operation, the final trial operation is also the cooling operation, and when the first trial operation is the heating operation, the final trial operation is also the heating operation. When the final trial operation is the cooling operation, the first control unit 20c performs capacity control to control the capacity of the compressor 21 such that the evaporation temperature of the refrigerant in the refrigerant circuit 10 approaches the target evaporation temperature. The target evaporation temperature in the final trial operation is the same as the target evaporation temperature during the cooling operation as the normal operation. When the final trial operation is the heating operation, the first control unit 20c performs capacity control to control the capacity of the compressor 21 such that the condensation temperature of the refrigerant in the refrigerant circuit 10 approaches the target condensation temperature. The target condensation temperature in the final trial operation is the same as the target condensation temperature during the heating operation as the normal operation. When the state of the refrigerant in the refrigerant circuit 10 is stabilized, the opening degree of the second expansion valve 33 of each of the utilization units 30 at the time when the refrigerant of the target filling amount is circulated is acquired as the final trial operation data. When the final trial operation data is acquired, the compressor 21 is stopped. The first control unit 20c stores the final trial operation data in the first storage 20d.

Next, the normal operation data is acquired during the normal operation after filling the refrigerant circuit 10 with the target filling amount (step S5). As described above, the normal operation is the heating operation, the cooling operation, or the like selected by the user with the remote controller 36.

Next, the presence or absence of a refrigerant leakage from the refrigerant circuit 10 is determined on the basis of the normal operation data and the first trial operation data (step S6). The step (S6) of determining according to the present embodiment includes determining the presence or absence of a refrigerant leakage from the refrigerant circuit 10 on the basis of the normal operation data, the first trial operation data, and the final trial operation data. The step (S5) of acquiring the normal operation data and the step (S6) of determining are executed as follows, for example.

Specifically, the first control unit 20c constantly acquires data during the normal operation, and sets, as the normal operation data, data acquired when a condition similar to the condition of the first trial operation is satisfied. Here, the first control unit 20c sets, as the normal operation data, data acquired when all the utilization units 30 perform the same cooling operation or heating operation as in the first trial operation. As the normal operation data, the opening degree of the second expansion valve 33 of each utilization unit 30 during the normal operation is acquired. The first control unit 20c reads the first trial operation data from the first storage 20d, compares the normal operation data with the first trial operation data, and determines that the refrigerant has leaked from the refrigerant circuit 10 when the normal operation data is in a state similar to the first trial operation data. Here, the first control unit 20c reads the first trial operation data and the final trial operation data from the first storage 20d, compares the normal operation data, the first trial operation data, and the final trial operation data, and determines that the refrigerant has leaked from the refrigerant circuit 10 when the normal operation data is in a state closer to the first trial operation data from the final trial operation data. For example, the first control unit 20c determines that the refrigerant has leaked from the refrigerant circuit 10 when a temporal change in the opening degree of the second expansion valve 33 as the normal operation data has approached the opening degree of the second expansion valve 33 as the first trial operation data from the opening degree of the second expansion valve 33 as the final trial operation data.

Here, an example of a determination method of the first control unit 20c in the step (S6) of determining will be described. It is assumed that the first trial operation and the normal operation perform the cooling operation in which the target evaporation temperature is constant. In this case, in the first trial operation, since a refrigerant amount is smaller than the target filling amount, the opening degree of the second expansion valve 33 becomes larger than in a case where the refrigerant of the target filling amount circulates due to a low evaporation temperature. Therefore, when the opening degree of the second expansion valve 33 as the normal operation data increases so as to approach the opening degree of the second expansion valve 33 as the first trial operation data, the first control unit 20c determines that the refrigerant is leaking.

When determining that there is no refrigerant leakage in the step (S6) of determining, the first control unit 20c continues the normal operation in response to a request from the user, and appropriately executes the step (S5) of acquiring the normal operation data and the step (S6) of determining. On the other hand, when determining that there is a refrigerant leakage in the step (S6) of determining, the first control unit 20c transmits the determination to the server 40. Then, the server 40 notifies the information device 50 of the user (step S7) of the determination.

(7) Characteristics

(7-1)

The refrigerant leakage determination method according to the present embodiment includes the following steps. The refrigerant circuit 10 formed by connecting the heat source unit 20 and the utilization unit 30 by the connection pipes 5 and 6 is filled with the refrigerant of the first filling amount smaller than the target filling amount (step S1). The first trial operation of circulating the refrigerant of the first filling amount in the refrigerant circuit 10 is performed, and the first trial operation data is acquired (step S2). After the step (S2) of acquiring, the refrigerant circuit 10 is filled with the refrigerant until the target filling amount is reached (step S3). The normal operation data is acquired during the normal operation after filling the refrigerant circuit 10 with the target filling amount (step S5). Subsequently, the presence or absence of a refrigerant leakage from the refrigerant circuit 10 is determined on the basis of the normal operation data and the first trial operation data (step S6).

In the refrigerant leakage determination method according to the present embodiment, the first trial operation of circulating the refrigerant of the first filling amount smaller than the target filling amount is performed, and the first trial operation data is acquired. The first trial operation data is data indicating a behavior at the time when the refrigerant leaks. Thus, by comparing the normal operation data acquired during the normal operation after filling the refrigerant circuit 10 with the target filling amount with the first trial operation data, it is possible to determine the presence or absence of a refrigerant leakage from the refrigerant circuit 10 regardless of the construction location, the pipe length, and the like of the refrigeration cycle apparatus 1 including the heat source unit 20, the utilization unit 30, and the connection pipes 5 and 6. Therefore, in the refrigerant leakage determination method according to the present embodiment, it is not necessary to perform a special operation with a constant condition in order to determine a refrigerant leakage, and a refrigerant leak can be determined in the normal operation. In the refrigerant leakage determination method according to the present embodiment, the determination of the refrigerant leakage can be performed by comparing the normal operation data with the first trial operation data without considering the construction location, the pipe length, and the like, and the determination accuracy can be improved.

The refrigerant leakage determination method according to the present embodiment further includes the step (S4) of performing the final trial operation for circulating the target filling amount of the refrigerant in the refrigerant circuit 10 and acquiring the final trial operation data.

(7-2)

The refrigeration cycle apparatus 1 according to the present embodiment includes the heat source unit 20, the utilization unit 30, and the connection pipes 5 and 6 connecting the heat source unit 20 and the utilization unit 30. The refrigeration cycle apparatus 1 includes the refrigerant circuit 10 and the first control unit 20c. The refrigerant circuit 10 is constituted by connecting the heat source unit 20 and the utilization unit 30 to each other by the connection pipes 5 and 6. The first control unit 20c controls the operation of the refrigerant circuit 10. The first control unit 20c acquires the first trial operation data by performing the first trial operation of circulating the refrigerant of the first filling amount smaller than the target filling amount in the refrigerant circuit 10.

In the refrigeration cycle apparatus 1 according to the present embodiment, the first control unit 20c acquires the first trial operation data by performing the first trial operation of circulating the refrigerant of the first filling amount smaller than the target filling amount. The first trial operation data is data indicating a behavior at the time when the refrigerant leaks. Thus, the first control unit 20c compares the normal operation data acquired during the normal operation after filling the refrigerant circuit 10 with the target filling amount with the first trial operation data, and it is thus possible to determine the presence or absence of a refrigerant leakage from the refrigerant circuit 10 regardless of the construction location, the pipe length, and the like of the refrigeration cycle apparatus 1. Therefore, the refrigeration cycle apparatus 1 according to the present embodiment is not required to perform a special operation with a constant condition in order to determine a refrigerant leakage, and can determine a refrigerant leak in the normal operation. Since the first control unit 20c determines a refrigerant leakage by comparing the normal operation data with the first trial operation data without considering the construction location, the pipe length, and the like, the refrigeration cycle apparatus 1 according to the present embodiment can improve the determination accuracy.

The first control unit 20c of the refrigeration cycle apparatus 1 according to the present embodiment has modes of a plurality of trial operations (in the present embodiment, the first trial operation and the final trial operation), and acquires trial operation data of each of the plurality of trial operations.

(8) Modifications

(8-1) Modification 1

In the embodiment, an example has been described in which the trial operation of circulating the refrigerant of a filling amount smaller than the target filling amount is only the first trial operation, but the present disclosure is not limited to this example. The refrigerant leakage determination method and the refrigeration cycle apparatus 1 of the present disclosure may perform a plurality of trial operations of circulating the refrigerant of a filling amount smaller than the target filling amount. The refrigerant leakage determination method and the refrigeration cycle apparatus according to this modification perform a second trial operation of circulating the refrigerant of a filling amount smaller than the target filling amount, in addition to the first trial operation.

(8-1-1) Refrigeration Cycle Apparatus

The first control unit 20c according to this modification acquires second trial operation data by performing a second trial operation of circulating the refrigerant of a second filling amount larger than the first filling amount and smaller than the target filling amount in the refrigerant circuit 10. The second filling amount is, for example, 50% or more and less than 100% of the target filling amount, and is set to 90% of the target filling amount in this modification.

Specifically, the first control unit 20c according to this modification has three modes, namely, a first trial operation of circulating the refrigerant having the first filling amount smaller than the target filling amount, a second trial operation of circulating the refrigerant of the second filling amount larger than the first filling amount and smaller than the target filling amount, and a final trial operation of circulating the refrigerant of the target filling amount. The modes of the first trial operation and the final trial operation are similar to the modes in the embodiment. The added second trial operation will be described below.

When the first input unit 20b receives a command to execute the second trial operation, the first control unit 20c operates each unit constituting the heat source unit 20 to execute the second trial operation, and sends a command to the second control unit 35 of the utilization unit 30 to operate each part constituting the utilization unit 30. Then, the first control unit 20c acquires the second trial operation data during the second trial operation. The second trial operation data is, for example, an opening degree of the second expansion valve 33 of each utilization unit 30. Then, the first control unit 20c stores the acquired second trial operation data in the first storage 20d.

The first control unit 20c acquires the normal operation data during the normal operation, and determines the presence or absence of a refrigerant leakage from the refrigerant circuit 10 on the basis of the normal operation data, the first trial operation data, the second trial operation data, and the final trial operation data. Here, in the normal operation, the first control unit 20c compares the normal operation data at the time when a condition similar to the condition of the first trial operation is satisfied, the first trial operation data, the second trial operation data, and the final trial operation data, and when the normal operation data is similar to the first trial operation data or the second trial operation data form the final trial operation data, the first control unit 20c determines that the refrigerant has leaked from the refrigerant circuit 10.

The first trial operation data, the second trial operation data, and the final trial operation data acquired by the first control unit 20c are, for example, data on the opening degree of each second expansion valve 33 at the time when all of the plurality of utilization units 30 performs the cooling operation. The first control unit 20c acquires the opening degree of each of the second expansion valves 33 as the normal operation data when all the utilization units performs the cooling operation during the normal operation. The first control unit 20c compares the opening degree of each second expansion valve 33 as the first trial operation data, the opening degree of each second expansion valve 33 as the second trial operation data, the opening degree of each second expansion valve 33 as the final trial operation data, and the opening degree of each second expansion valve 33 as the normal operation data. Specifically, whether presence or absence of a refrigerant leakage is determined by calculating how close the opening degree of each second expansion valve 33 during the normal operation is to the opening degree of each second expansion valve 33 during the first trial operation and each second expansion valve 33 during the second trial operation from the opening degree of each second expansion valve 33 during the final trial operation. The first control unit 20c considers a change from the opening degree of each second expansion valve 33 in the first trial operation data to the opening degree of each second expansion valve 33 in the second trial operation data. The change in the opening degree of the second expansion valve is, for example, linear, quadratic curve, and the like. Note that target evaporation temperatures in the first trial operation, the final trial operation, and the normal operation are the same.

The first input unit 20b according to this modification further includes a button for receiving a command to execute the second trial operation.

(8-1-2) Refrigerant Leakage Determination Method

A refrigerant leakage determination method according to this modification, which is basically similar to the refrigerant leakage determination method according to the embodiment, is different in that the method further includes, as shown in FIG. 5, a step (S11) of filling the refrigerant circuit with the refrigerant of the second filling amount and a step (S12) of acquiring the second trial operation data.

Specifically, as in the embodiment, the step (S1) of filling the refrigerant circuit with the refrigerant of the first refrigerant amount and the step (S2) of acquiring the first trial operation data are performed. Next, the refrigerant circuit 10 is filled with the refrigerant of the second filling amount larger than the first filling amount and smaller than the target filling amount (step S11). This step (S11) is executed, for example, as follows.

The refrigerant circuit 10 having been filled with the refrigerant of the first filling amount is filled with the refrigerant of the difference between the second filling amount (90%) and the first filling amount (70%). Here, by additionally filling the refrigerant circuit 10 with the refrigerant of 20% of the target filling amount, the refrigerant circuit 10 is filled with the refrigerant of the second filling amount (90%). The method of additionally filling the refrigerant circuit 10 with the refrigerant is similar to the step (S1) of filling the refrigerant circuit 10 with the refrigerant of the first filling amount.

Next, the second trial operation of circulating the refrigerant of the second filling amount in the refrigerant circuit 10 is performed, and the second trial operation data is acquired (step S12). This step (S12) is executed, for example, as follows.

Specifically, when the first input unit 20b receives a command to execute the second trial operation, the first control unit 20c operates each part constituting the refrigeration cycle apparatus 1 in cooperation with the second control unit 35, and circulates the refrigerant of the second filling amount in the refrigerant circuit 10 such that all the utilization units 30 performs the cooling operation or the heating operation. When the first trial operation is the cooling operation, the second trial operation is also the cooling operation, and when the first trial operation is the heating operation, the second trial operation is also the heating operation. When the second trial operation is the cooling operation, the first control unit 20c performs capacity control to control the capacity of the compressor 21 such that the evaporation temperature of the refrigerant in the refrigerant circuit 10 approaches the target evaporation temperature. The target evaporation temperature in the second trial operation is the same as the target evaporation temperature during the cooling operation as the normal operation. When the second trial operation is the heating operation, the first control unit 20c performs capacity control to control the capacity of the compressor 21 such that the condensation temperature of the refrigerant in the refrigerant circuit 10 approaches the target condensation temperature. The target condensation temperature in the second trial operation is the same as the target condensation degree during the heating operation as the normal operation. When the state of the refrigerant in the refrigerant circuit 10 is stabilized, the opening degree of the second expansion valve 33 of each of the utilization units 30 at the time when the refrigerant of the second filling amount is circulated is acquired as the second trial operation data. When acquiring the second trial operation data, the first control unit 20c stops the compressor 21. The first control unit 20c stores the second trial operation data in the first storage 20d.

Next, the refrigerant circuit 10 is filled with the refrigerant until the target filling amount is reached (step S3). In this step (S3), the refrigerant circuit 10 having been filled with the refrigerant of the second filling amount is filled with the refrigerant of the difference between the target filling amount and the second filling amount. Here, by additionally filling the refrigerant circuit 10 with the refrigerant of 10% of the target filling amount as an additional amount of refrigerant estimated in advance, while measuring the weight of the container, the refrigerant circuit 10 is filled with the refrigerant of the target filling amount.

Next, as in the first embodiment, the step (S4) of acquiring the final trial operation data is executed.

Next, the normal operation data is acquired during the normal operation after filling the refrigerant circuit 10 with the target filling amount (step S5). Next, the presence or absence of a refrigerant leakage from the refrigerant circuit 10 is determined on the basis of the normal operation data, the first trial operation data, and the second trial operation data (step S6). The step (S5) of acquiring the normal operation data and the step (S6) of determining are executed as follows, for example.

Specifically, as in the embodiment, the first control unit 20c acquires the normal operation data. Then, the first control unit 20c reads the first trial operation data, the second trial operation data, and the final trial operation data from the first storage 20d, compares the normal operation data, the first trial operation data, the second trial operation data, and the final trial operation data, and determines that the refrigerant has leaked from the refrigerant circuit when the normal operation data is in a state similar to the first trial operation data or the second trial operation data. For example, the first control unit 20c determines that the refrigerant has leaked from the refrigerant circuit 10 when a temporal change in the opening degree of the second expansion valve 33 as the normal operation data has approached the opening degree of the second expansion valve 33 as the second trial operation data or the opening degree of the second expansion valve 33 as the first trial operation data from the opening degree of the second expansion valve 33 as the final trial operation data. Here, the first control unit 20c determines the presence or absence of a refrigerant leakage from the refrigerant circuit 10 from a state of change in the opening degree of the second expansion valve 33 on the basis of the first trial operation data, the second trial operation data, and the final trial operation data.

(8-1-3) Characteristics

The refrigerant leakage determination method according to this modification further includes the following steps. The refrigerant circuit 10 is filled with the refrigerant of the second filling amount larger than the first filling amount and smaller than the target filling amount (S11). The second trial operation of circulating the refrigerant of the second filling amount in the refrigerant circuit 10 is performed, and the second trial operation data is acquired (S12). The step (S6) of determining includes determining the presence or absence of a refrigerant leakage from the refrigerant circuit 10 on the basis of the normal operation data, the first trial operation data, and the second trial operation data.

Here, the second trial operation of circulating the refrigerant of the second filling amount between the first filling amount and the target filling amount is performed, and the second trial operation data is acquired. The second trial operation data indicates a behavior at the time when the refrigerant leaks and is different from the first trial operation data. Therefore, by comparing the normal operation data acquired during the normal operation after filling the refrigerant circuit with the target filling amount with the first trial operation data and the second trial operation data, the accuracy of the determination of the presence or absence of a refrigerant leakage can be improved.

In the refrigeration cycle apparatus 1 according to this modification, the first control unit 20c acquires second trial operation data by performing the second trial operation of circulating the refrigerant of the second filling amount larger than the first filling amount and smaller than the target filling amount in the refrigerant circuit 10.

Here, the first control unit 20c acquires the second trial operation data by performing the second trial operation of circulating the refrigerant of the second filling amount between the first filling amount and the target filling amount. The second trial operation data indicates a behavior at the time when the refrigerant leaks and is different from the first trial operation data. Therefore, by comparing the normal operation data acquired during the normal operation after filling the refrigerant circuit with the target filling amount with the first trial operation data and the second trial operation data, the accuracy of the determination of the presence or absence of a refrigerant leakage can be improved.

(8-2) Modification 2

In the embodiment, an example has been described in which the first trial operation of circulating the refrigerant of the first filling amount of 50% or more of the target filling amount is performed, but the present disclosure is not limited to this example. In this modification, a trial operation of circulating the refrigerant of less than 50% of the target filling amount is further performed.

Specifically, the first control unit 20c of the refrigeration cycle apparatus according to this modification acquires third trial operation data by performing a third trial operation of circulating the refrigerant of a third filling amount smaller than the first filling amount in the refrigerant circuit 10. The third filling amount is, for example, less than 50% of the target filling amount, and is set to 30% of the target filling amount in this modification.

The refrigerant leakage determination method according to this modification further includes, prior to the step (S1) of filling the refrigerant circuit 10 with the refrigerant of the first refrigerant amount, a step of filling the refrigerant circuit 10 with the refrigerant of the third refrigerant amount smaller than the first filling amount, and a step of acquiring the third trial operation data by performing the third trial operation of circulating the refrigerant of the third filling amount in the refrigerant circuit 10.

Specifically, in the step of filling the refrigerant circuit 10 with the refrigerant of the third filling amount, the heat source unit 20 filled with the refrigerant of the third filling amount or less is prepared as the initial filling amount. Then, the heat source unit 20 and the plurality of utilization units 30 are connected by the connection pipes 5 and 6. In this manner, the refrigerant circuit 10 filled with the refrigerant of the initial filling amount can be formed. When the initial filling amount is less than the third filling amount, the refrigerant circuit 10 is filled with the refrigerant so as to reach the third refrigerant amount.

In the step of acquiring the third trial operation data, similarly to the first trial operation and the final trial operation, the third trial operation is performed, and the third trial operation data is acquired.

The step (S6) of determining shown in FIG. 5 includes determining the presence or absence of a refrigerant leakage from the refrigerant circuit 10 on the basis of the normal operation data, the first to third trial operation data, and the final trial operation data.

As in this modification, the refrigerant leakage determination method and the refrigeration cycle apparatus 1 of the present disclosure may perform a trial operation of circulating the refrigerant of any filling amount smaller than the target filling amount.

(8-3) Modification 3

In the embodiment, after the first trial operation data is acquired, the compressor 21 is stopped (step S2), the refrigerant circuit 10 is additionally filled with the refrigerant (step S3), and the final trial operation is performed (step S4), but the present disclosure is not limited to this configuration. In this modification, after the first trial operation data is acquired, the compressor 21 is not stopped (step S2), the refrigerant circuit 10 is additionally filled with the refrigerant (step S3), and the final trial operation is performed (step S4).

Specifically, after the first trial operation of circulating the refrigerant of the first filling amount smaller than the target filling amount is performed, the compressor 21 is not stopped, the refrigerant circuit 10 is additionally filled with the refrigerant, and when the target filling amount is reached, the first input unit 20b executes the final trial operation, and the final trial operation data is acquired.

As in Modifications 1 and 2, this modification can also be applied to a case where trial operations with different filling amounts are performed three or more times. This modification can reduce time required for the entire plurality of trial operations.

(8-4) Modification 4

In the embodiment, an example in which the opening degree of the second expansion valve 33 is used has been described as a method of determining the presence or absence of a refrigerant leakage, but the present disclosure is not limited to this example. In the refrigerant leakage determination method and refrigeration cycle apparatus 1 of the present disclosure, as a method of determining the presence or absence of a refrigerant leakage, for example, the opening degree of the second expansion valve 33, a degree of superheating at an outlet the evaporator (the second heat exchanger 31 or the first heat exchanger 23), a degree of subcooling at an outlet of the condenser (the first heat exchanger 23 or the second heat exchanger 31), a liquid pipe temperature detected at a liquid pipe outlet of the utilization unit 30, and the like may be used alone or in combination. In other words, the first trial operation data, the final trial operation data, and the normal operation data are at least one piece of data of the opening degree of the second expansion valve 33, the degree of superheating at the outlet of the evaporator (the second heat exchanger 31 or the first heat exchanger 23), the degree of subcooling at the outlet of the condenser (the first heat exchanger 23 or the second heat exchanger 31), or the liquid pipe temperature detected at the liquid pipe outlet of the utilization unit 30. The first control unit 20c determines that the refrigerant is leaking when, for example, the degree of superheating at the outlet of the evaporator is large, the degree of subcooling at the outlet of the condenser is small, or the liquid pipe temperature detected at the liquid pipe outlet of the utilization unit 30 is low so that the normal operation data approaches the first trial operation data.

As the degree of subcooling, for example, a temperature difference obtained by converting the pressure of the refrigerant detected by the discharge pressure sensor 61 into a saturation temperature of the refrigerant and subtracting the saturation temperature from the temperature of the refrigerant detected by the liquid-side temperature sensor 65 can be used. As the degree of superheating, for example, a temperature difference obtained by converting the pressure of the refrigerant detected by the suction pressure sensor 63 into a saturation temperature of the refrigerant and subtracting the temperature of the refrigerant detected by the suction temperature sensor 64 from the saturation temperature can be used.

(8-5) Modification 5

In the embodiment, the refrigerant circuit is filled with the refrigerant manually, but the present disclosure is not limited to this configuration, and the refrigerant circuit may be filled with the refrigerant automatically.

(8-6) Modification 6

In the embodiment, the refrigeration cycle apparatus 1 in which the plurality of utilization units 30 can individually perform the cooling operation or the heating operation has been described as an example, but the present disclosure is not limited to this example. In the refrigeration cycle apparatus according to this modification, the plurality of utilization units 30 cannot perform the cooling operation or the heating operation individually. In this case, for example, the second expansion valve 33 common to the plurality of utilization units 30 is provided.

(8-7) Modification 7

In the embodiment, the refrigeration cycle apparatus 1 includes three utilization units 30, but the number of the utilization units 30 is not limited. The refrigeration cycle apparatus of the present disclosure may include two or more utilization units 30 or may include one utilization unit 30.

(8-8) Modification 8

In the embodiment, the refrigeration cycle apparatus 1 that performs the cooling operation and the heating operation has been described as an example, but the refrigeration cycle apparatus of the present disclosure is not limited to this example, and may further perform a dehumidifying operation and the like. The refrigeration cycle apparatus according to this modification is an air conditioner dedicated to cooling.

(8-9) Modification 9

In the embodiment, the air conditioner has been described as an example of the refrigeration cycle apparatus 1, but the present disclosure is not limited to this example. The refrigeration cycle apparatus of the present disclosure may be, for example, a hot water supply apparatus, a floor heating apparatus, a refrigerating apparatus, or the like.

While the embodiment of the present disclosure has been described above, it will be understood that various changes in forms and details can be made without departing from the gist and scope of the present disclosure recited in the claims. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated.

REFERENCE SIGNS LIST

• • 1: refrigeration cycle apparatus
  • 5, 6: connection pipe
  • 10: refrigerant circuit
  • 20: heat source unit
  • 20c: first control unit (control unit)
  • 30: utilization unit
  • 35: second control unit

CITATION LIST

Patent Literature

• Patent Literature 1: WO 2015/004747 A