Refrigerant loading method and refrigeration cycle device

Abstract

In a refrigeration cycle device using a non-azeotropic refrigerant mixture in which two or more types of refrigerants having different boiling points are mixed, this refrigerant loading method executes, when the non-azeotropic refrigerant mixture has leaked, either a first method in which the non-azeotropic refrigerant mixture is reloaded after all the non-azeotropic refrigerant mixture is recovered, or a second method in which the non-azeotropic refrigerant mixture is replenished without recovering the non-azeotropic refrigerant mixture, on the basis of the leaked amount of the non-azeotropic refrigerant mixture.

Description

Refrigerant filling method and refrigeration cycle device

[0001] The present disclosure relates to a refrigerant filling method and a refrigeration cycle device, and particularly to a refrigerant filling method for a zeotropic mixture refrigerant and a refrigeration cycle device using a zeotropic mixture refrigerant.

[0002] Conventional refrigeration cycle devices have a heat exchanger, and the heat exchanger functions as, for example, a condenser mounted in an indoor unit. In a refrigeration cycle device, the liquid refrigerant condensed by the heat exchanger is depressurized by an expansion device and becomes a gas-liquid two-phase state in which a gas refrigerant and a liquid refrigerant are mixed. Then, in the heat exchanger that functions as an evaporator mounted in an outdoor unit, the liquid refrigerant among the gas-liquid two-phase state refrigerant evaporates to become a low-pressure gas refrigerant. After that, the low-pressure gas refrigerant flows into a compressor, is compressed by the compressor to become a high-temperature and high-pressure gas refrigerant, and is discharged again from the compressor. In the refrigeration cycle device, this cycle is repeated.

[0003] By the way, in such a refrigeration cycle device, if the refrigerant is installed in a state where it leaks slightly due to poor connection work of refrigerant pipes or the like, the amount of refrigerant filled in the refrigeration cycle device decreases over time compared to the amount of refrigerant required for operation. When the amount of refrigerant decreases compared to the required amount of refrigerant, the operating capacity decreases, or the refrigerant noise in the pipes increases. Therefore, means for replenishing the refrigerant at the installation location to ensure the filling amount required for operation have been proposed.

[0004] Here, when a zeotropic mixture refrigerant in which refrigerants having different boiling points are mixed is used as the refrigerant, if the refrigerant leaks in a region where gas and liquid are mixed, the refrigerant with a lower boiling point leaks preferentially, and the composition of the filled refrigerant changes. When the composition of the filled refrigerant changes, the physical properties of the refrigerant change, the safety such as flammability or toxicity of the refrigerant decreases, and a decrease in functions such as control failure or performance failure may occur.

[0005] Therefore, for example, in Patent Document 1, a refrigerant filling method for replenishing a refrigerant having a predetermined composition in a liquid state has been proposed. According to the filling method of Patent Document 1, it can be replenished with a refrigerant having a predetermined composition supplied from a refrigerant cylinder.

[0006] Japanese Patent Application Publication No. 11-270933

[0007] After a leak, the refrigerant composition in the system changes from its initial composition. Therefore, the refrigerant charging method described in Patent Document 1 has the problem that even when a refrigerant of a predetermined charging composition is supplied, the refrigerant composition changes from its initial composition.

[0008] This disclosure aims to provide a refrigerant charging method and a refrigeration cycle device that can achieve both improved quality and improved performance.

[0009] The refrigerant charging method according to this disclosure is used in a refrigeration cycle device that uses a non-azeotropic mixed refrigerant, which is a mixture of two or more refrigerants with different boiling points. In the event of leakage of the non-azeotropic mixed refrigerant, the method includes either a first method in which the non-azeotropic mixed refrigerant is fully recovered and then refilled based on the amount of leakage, or a second method in which the non-azeotropic mixed refrigerant is replenished without any recovery.

[0010] Furthermore, the refrigeration cycle device according to this disclosure comprises a refrigerant circuit in which a non-azeotropic mixed refrigerant, which is a mixture of two or more refrigerants with different boiling points, is circulated, and a control device that controls the refrigerant circuit, wherein the control device determines whether the amount of leakage of the non-azeotropic mixed refrigerant is equal to or greater than a specified value, and if the amount of leakage is equal to or greater than the specified value, it determines and notifies a first method of recovering all of the non-azeotropic mixed refrigerant and then refilling it, and if the amount of leakage is less than the specified value, it determines and notifies a second method of supplementing the non-azeotropic mixed refrigerant without recovering it.

[0011] According to this disclosure, since the first method or the second method is selected depending on the amount of refrigerant leakage, changes in the composition of the refrigerant can be suppressed, and both the quality and performance of the refrigeration cycle equipment can be improved.

[0012] This is a refrigerant circuit diagram of a refrigeration cycle device according to Embodiment 1. This is a refrigerant circuit diagram of a refrigeration cycle device according to Embodiment 1 during refrigerant charging operation. This is a graph showing the low-boiling point refrigerant composition in relation to the amount of refrigerant leakage in a refrigeration cycle device according to Embodiment 1. This is a graph showing the low-boiling point refrigerant composition in relation to the number of recharging cycles in a refrigerant charging method according to Embodiment 1. This is a graph showing the low-boiling point refrigerant composition in relation to the number of recharging cycles in a refrigerant charging method according to Embodiment 1. This is a flowchart explaining the process for determining the refrigerant charging method according to Embodiment 1. This is a flowchart explaining the process for determining the refrigerant charging method according to Embodiment 2. This is a graph showing the cooling capacity ratio in relation to the amount of refrigerant leakage in a refrigeration cycle device according to Embodiment 2. This is a graph showing the heating capacity ratio in relation to the amount of refrigerant leakage in a refrigeration cycle device according to Embodiment 2. This is a flowchart explaining the process for determining the refrigerant charging method according to Embodiment 3. This is a graph showing the degree of subcooling at the outlet of the indoor heat exchanger during cooling operation in relation to the amount of refrigerant leakage in a refrigeration cycle device according to Embodiment 3. This is a flowchart explaining the process for determining the refrigerant charging method according to Embodiment 4. This is a refrigerant circuit diagram of a refrigeration cycle device according to Embodiment 4. This is a refrigerant circuit diagram explaining the case where refrigerant leaks in a refrigeration cycle device according to Embodiment 4. This is a refrigerant circuit diagram of a refrigeration cycle device according to Embodiment 5. This is a graph showing the degree of subcooling at the outlet of the indoor heat exchanger during heating operation in relation to the amount of refrigerant leakage in the refrigeration cycle device according to Embodiment 5. This is a refrigerant circuit diagram of a modified example of a refrigeration cycle device according to Embodiment 5.

[0013] The embodiments for implementing this disclosure will be described with reference to the attached drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are simplified or omitted as appropriate. In the following description, for convenience, the positional relationships of each structure may be expressed based on the illustrated state. This disclosure is not limited to the following embodiments, and any combination of embodiments, any modification of any component of each embodiment, or any omission of any component of each embodiment is possible without departing from the spirit of this disclosure. In addition, the dimensional relationships or shapes of each component in each drawing may differ from those of the actual components. Furthermore, the positional relationships between each component, such as the top-down relationship, are, in principle, as they are when installed in a usable state. However, in order to facilitate understanding, terms indicating direction, such as "up," "down," "right," "left," "front," and "back," will be used as appropriate, but these notations are merely for the convenience of explanation and do not limit the arrangement and orientation of the device or parts.

[0014] Embodiment 1. <Configuration of Refrigeration Cycle Device 200> Figure 1 is a refrigerant circuit diagram of a refrigeration cycle device 200 according to Embodiment 1. The refrigeration cycle device 200 is used for refrigeration or air conditioning purposes in, for example, refrigerators, freezers, vending machines, air conditioning systems, refrigeration systems, and water heaters. As shown in Figure 1, the refrigeration cycle device 200 comprises an outdoor unit 201 and an indoor unit 202. In Figure 1, the solid line shows the flow of refrigerant during heating operation, and the dashed line shows the flow of refrigerant during cooling operation.

[0015] The refrigerant is, for example, a non-azeotropic mixed refrigerant. Examples of refrigerants include olefin-based refrigerants such as tetrafluoropropene, ethylene-based refrigerants such as difluoroethylene, ethane-based refrigerants such as tetrafluoroethane, propane, and CO2. ２ It is a mixed refrigerant containing one or more of the following: , or DME (dimethyl ether). Examples of olefin-based refrigerants include HFO1234yf or HFO1234ze(E).

[0016] The refrigeration cycle system 200 is, for example, a multi-connection system in which two or more indoor unit units 202 are connected. The multiple indoor unit units 202 are connected in parallel to, for example, an outdoor unit unit 201. The outdoor unit unit 201 includes a compressor 14, an accumulator 13, a flow path switching device 41, an outdoor heat exchanger 4, an outdoor fan 5, and an indoor expansion valve 21. The indoor unit unit 202 includes an indoor heat exchanger 1, an indoor fan 18, and an indoor expansion valve 21. The compressor 14, the flow path switching device 41, the outdoor heat exchanger 4, the indoor expansion valve 21, and the indoor heat exchanger 1 are connected in a ring by piping that constitutes a refrigerant flow path 7. Refrigerant flows through the refrigerant flow path 7 as the working fluid. The indoor heat exchanger 1 is an example of a heat exchanger on the user side. The outdoor heat exchanger 4 is an example of a heat exchanger on the heat source side. Outdoor unit 201 is an example of an outdoor unit, and indoor unit 202 is an example of an indoor unit.

[0017] The compressor 14 draws in refrigerant, compresses it to a high temperature and high pressure state, and discharges it. The refrigerant compressed by the compressor 14 is discharged and sent to the flow path switching device 41. The compressor 14 can be composed of, for example, a rotary compressor, a scroll compressor, a screw compressor, or a reciprocating compressor. The compressor 14 is effective whether it is a high-pressure shell type or a low-pressure shell type, but the effect of suppressing oil leakage is particularly increased in the high-pressure shell type. The accumulator 13 separates the refrigerant into gas and liquid, and allows only the gaseous refrigerant to flow into the compressor 14, and is located on the suction side of the compressor 14.

[0018] The flow path switching device 41 is, for example, a four-way valve. The flow path switching device 41 switches the direction of refrigerant flow in the refrigerant flow path 7. The flow path switching device 41 switches the direction of refrigerant flow in the refrigeration cycle device 200 between heating operation and cooling operation.

[0019] During heating operation, the outdoor heat exchanger 4 acts as an evaporator, exchanging heat between the refrigerant flowing into it and the outdoor air, causing the refrigerant to evaporate and vaporize. During cooling operation, the outdoor heat exchanger 4 acts as a condenser, exchanging heat between the refrigerant flowing into it and the outdoor air, causing the refrigerant to condense and liquefy.

[0020] The outdoor heat exchanger 4 functions as a heat exchanger that exchanges heat between the refrigerant flowing through the refrigerant channel 7 and a heat transport medium such as air flowing outside the pipe. The outdoor heat exchanger 4 is composed of, for example, a fin-and-tube type heat exchanger, a microchannel heat exchanger, a shell-and-tube type heat exchanger, a heat pipe type heat exchanger, a double-tube type heat exchanger, or a plate type heat exchanger.

[0021] The outdoor fan 5 supplies a heat exchange fluid, such as air, to the outdoor heat exchanger 4. The outdoor fan 5 is positioned adjacent to the outdoor heat exchanger 4 to improve the efficiency of heat exchange between the refrigerant and the outdoor air in the outdoor heat exchanger 4. Depending on the working fluid and operating conditions such as flow rate or static pressure, the outdoor fan 5 is composed of a propeller fan, a line flow fan (registered trademark), a multi-blade centrifugal fan, or a water pump.

[0022] During heating operation, the indoor heat exchanger 1 functions as a condenser, exchanging heat between the refrigerant flowing into it and the indoor air, condensing and liquefying the refrigerant. During cooling operation, the indoor heat exchanger 1 functions as an evaporator, exchanging heat between the refrigerant flowing into it and the indoor air, evaporating and vaporizing the refrigerant.

[0023] The indoor heat exchanger 1 functions like the outdoor heat exchanger 4, exchanging heat between the refrigerant flowing through the refrigerant channel 7 and a heat transport medium such as air flowing outside the pipe. The indoor heat exchanger 1 can be composed of, for example, a fin-and-tube heat exchanger, a microchannel heat exchanger, a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-tube heat exchanger, or a plate heat exchanger. The indoor heat exchanger 1 may also function as a heat exchanger that exchanges heat with water or the like instead of air to supply hot water or chilled water.

[0024] The indoor blower 18 supplies a heat exchange fluid, such as air, to the indoor heat exchanger 1. The indoor blower 18 is positioned adjacent to the indoor heat exchanger 1 to improve the efficiency of heat exchange between the refrigerant and indoor air in the indoor heat exchanger 1. Similar to the outdoor blower 5, the indoor blower 18 is composed of a propeller fan, a line flow fan (registered trademark), a multi-blade centrifugal fan, or a water pump, depending on the working fluid and operating conditions such as flow rate or static pressure.

[0025] The indoor expansion valve 21 functions as a pressure reducing valve or an expansion valve, and reduces pressure by expanding the refrigerant. The indoor expansion valve 21 is, for example, an electrically operated expansion valve capable of adjusting the flow rate of the refrigerant. However, the indoor expansion valve 21 is not limited to an electrically operated expansion valve, and may be a mechanical expansion valve employing a diaphragm in the pressure-receiving part, or part of it may be composed of a capillary tube or the like.

[0026] The control device 210 controls the overall operating state of the refrigeration cycle system 200, such as cooling operation or heating operation. The control device 210 may also control the flow path switching device 41 to switch the direction of refrigerant flow in the refrigerant flow path 7. The control device 210 may also control the compressor 14, for example, by controlling the discharge amount of compressed refrigerant by the rotation speed of the compressor 14. The control device 210 may also control the rotation amount of the outdoor blower 5. The control device 210 may also adjust the opening degree of the indoor expansion valve 21.

[0027] The control device 210 is composed of, for example, a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, also called a DSP (Digital Signal Processor)). The control device 210 has memory composed of, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs (Digital Versatile Disks), etc. The control device 210 performs processing using programs stored in memory. However, the control device 210 is not limited to this, and each part may be composed of separate, dedicated devices.

[0028] <Operation of the Refrigeration Cycle Unit 200> Next, the operation of the refrigeration cycle unit 200 will be explained, along with the flow of the refrigerant, using the case where the heat exchange fluid is air and the fluid being heat exchanged is a refrigerant as an example. First, the cooling operation performed by the refrigeration cycle unit 200 will be explained.

[0029] In the refrigeration cycle device 200, when the compressor 14 is driven, high-temperature and high-pressure gaseous refrigerant is discharged from the compressor 14. During cooling operation, the refrigerant flows through the refrigerant flow path 7 according to the arrows shown by the dashed lines. The high-temperature and high-pressure single-phase gaseous refrigerant discharged from the compressor 14 flows into the outdoor heat exchanger 4, which functions as a condenser, via the flow path switching device 41.

[0030] In the outdoor heat exchanger 4, heat exchange takes place between the high-temperature, high-pressure gaseous refrigerant that flows into the outdoor heat exchanger 4 and the air supplied by the outdoor blower 5. The refrigerant that has undergone heat exchange in the outdoor heat exchanger 4 condenses into a high-pressure single-phase liquid refrigerant or a gas-liquid two-phase refrigerant.

[0031] The high-pressure liquid refrigerant sent from the outdoor heat exchanger 4, which acts as a condenser, flows into the indoor expansion valve 21, where it is depressurized to a two-phase state consisting of low-pressure gaseous refrigerant and liquid refrigerant. The two-phase refrigerant then flows into the indoor heat exchanger 1, which functions as an evaporator, where heat exchange takes place between the two-phase refrigerant and the air supplied by the indoor blower 18. In the indoor heat exchanger 1, the liquid refrigerant from the two-phase refrigerant that has undergone heat exchange evaporates to become a low-pressure, single-phase gaseous refrigerant. The air that has undergone heat exchange with the refrigerant in the indoor heat exchanger 1 is supplied to the room, thereby cooling the room.

[0032] Low-pressure gaseous refrigerant flows out of the indoor heat exchanger 1, enters the compressor 14 via the flow path switching device 41, and is compressed again by the compressor 14 before being discharged. This cycle is repeated in the refrigeration cycle device 200 to perform cooling operation.

[0033] Next, the heating operation performed by the refrigeration cycle device 200 will be described. The high-temperature and high-pressure gaseous refrigerant compressed by the compressor 14 flows through the flow path switching device 41 into the indoor heat exchanger 1, which functions as a condenser, and is cooled while supplying heat to the indoor air, becoming a low-temperature liquid refrigerant and flowing out from the indoor heat exchanger 1.

[0034] The liquid refrigerant flowing out of the indoor heat exchanger 1 is depressurized by the indoor expansion valve 21 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, which then flows into the outdoor heat exchanger 4, which functions as an evaporator. The low-temperature, low-pressure gas-liquid two-phase refrigerant that flows into the outdoor heat exchanger 4 exchanges heat with the air supplied by the outdoor blower 5, absorbing heat from the outside air, causing the liquid refrigerant in the two-phase state to evaporate and become a low-pressure, single-phase gaseous refrigerant.

[0035] The low-pressure gaseous refrigerant flowing out from the outdoor heat exchanger 4 flows into the compressor 14 via the flow path switching device 41, where it is compressed again into high-temperature and high-pressure gaseous refrigerant. This cycle is repeated in the refrigeration cycle device 200 to perform heating operation.

[0036] <Refrigerant Charging Operation> Next, we will explain the operation of charging refrigerant in the event of a refrigeration cycle device 200 leak. When the refrigeration cycle device 200 is installed, it is filled with an amount of refrigerant appropriate to the installation location in order to ensure proper operation. If the refrigeration cycle device 200 is installed in a state where a small amount of refrigerant is leaking due to, for example, faulty connection of the refrigerant piping, the amount of refrigerant in the refrigeration cycle device 200 will decrease compared to the amount at the time of installation. If the amount of refrigerant continues to decrease, it may cause problems in the operation of the refrigeration cycle device 200. Therefore, during maintenance, the refrigeration cycle device 200 is charged with refrigerant to replenish the amount that has decreased, so that it returns to the initial amount at the time of installation.

[0037] Figure 2 is a refrigerant circuit diagram during refrigerant charging operation in the refrigeration cycle device 200 according to Embodiment 1. As shown in Figure 2, during refrigerant charging operation, for example, a maintenance worker connects a cylinder 32 to the refrigerant flow path 7. The cylinder 32 is a pressure vessel containing refrigerant. The cylinder 32 is connected to a three-way valve 34 provided in the refrigerant flow path 7 via a pressure-resistant hose (not shown).

[0038] In the control device 210, the operating mode is set to refrigerant charging mode, the compressor 14 is started, the flow path switching device 41 is switched to the cooling side, and the opening of the indoor expansion valve 21 is set to an opening close to fully closed. As a result, superheat control operation is performed in which the refrigerant in a superheated gas state flows from the indoor heat exchanger 1 to the compressor 14.

[0039] When the control device 210 opens the on / off valve 40, the refrigerant from the cylinder 32 flows through the three-way valve 34 into the refrigerant flow path 7 connecting the indoor heat exchanger 1 and the compressor 14, and the refrigerant is charged.

[0040] Once the refrigerant charging is complete, the control device 210 closes the on / off valve 40, and the refrigerant charging operation ends.

[0041] For the refrigeration cycle device 200, the determination of whether the leaked refrigerant has been replenished can be made, for example, by monitoring the temperature or pressure of the discharged refrigerant or the suction refrigerant of the compressor 14 during filling, that is, during additional charging. Specifically, the refrigerant filling amount can be determined by whether the temperature or pressure of the discharged refrigerant or the suction refrigerant of the compressor 14 reaches the designed temperature or pressure of the refrigerant during additional charging.

[0042] The refrigerant replenishment amount may be determined, for example, by operating to store the refrigerant circulating in the refrigerant flow path 7 in a certain section and measuring the change in the liquid level height at the time of leakage with respect to the liquid level height at the time of installation. The liquid level height can be measured, for example, by visual recognition from a glass window, attaching a level sensor, or calculating from the measurement results of refrigerant thermometers provided at multiple points.

[0043] The refrigerant filling amount may also be determined based on the operation characteristic data stored in advance in a state where the refrigerant filling amount has decreased and the operation characteristic data and the operation data at the time of leakage. Specifically, by comparing the operation data at the time of leakage with the operation characteristic data, the filling amount of the refrigerant remaining in the refrigerant flow path 7 can be estimated.

[0044] The refrigerant filling amount may also be determined by directly measuring the composition of the refrigerant with an optical measurement device. By measuring the composition of the refrigerant, the amount of leaked refrigerant can be estimated.

[0045] <Change in composition of azeotropic refrigerant mixture> Figure 3 is a graph showing the low-boiling refrigerant composition with respect to the refrigerant leakage amount in the refrigeration cycle device 200 according to Embodiment 1. In Figure 3, the low-boiling refrigerant composition indicates the ratio with respect to the low-boiling refrigerant composition at the time of design. As shown in Figure 3, in the refrigeration cycle device 200, as the refrigerant leakage amount increases, the composition of the low-boiling refrigerant in the azeotropic refrigerant mixture decreases accordingly. The designed composition of the refrigerant is determined by the combination of the refrigerants filled in the refrigeration cycle device 200 and its composition, and is selected according to the regulatory trends and economic efficiency in each country where the refrigeration cycle device 200 is used.

[0046] Since the refrigerant of the refrigeration cycle device 200 is azeotropic refrigerant mixture in which two or more refrigerants with different boiling points are mixed, the composition of the refrigerant leaking from the refrigeration cycle device 200 is not uniform, and the low-boiling refrigerant leaks preferentially. As a result, the composition of the refrigerant remaining inside the refrigeration cycle device 200 changes with respect to the composition at the time of design, and as the leakage amount increases, the composition of the low-boiling refrigerant decreases. In particular, focusing on gas leakage, the gas contains a larger amount of the low-boiling component than in the case of liquid. When the gas containing a larger amount of the low-boiling component than in the case of liquid mainly leaks, the composition of the low-boiling refrigerant decreases with respect to the composition of the high-boiling refrigerant. However, the rate at which the composition of the low-boiling refrigerant decreases depends on the designed composition of the refrigerant used in the refrigeration cycle device 200.

[0047] FIG. 4 is a graph showing the low-boiling refrigerant composition with respect to the number of refills in the refrigerant filling method according to the first embodiment. FIG. 5 is a graph showing the low-boiling refrigerant composition with respect to the number of refills in the refrigerant filling method according to the first embodiment, and shows the low-boiling refrigerant composition when the leakage amount increases. In FIGS. 4 and 5, the low-boiling refrigerant composition indicates the ratio with respect to the low-boiling refrigerant composition at the time of design.

[0048] As shown in FIGS. 4 and 5, as the number of refills increases, the composition of the refrigerant at the time of refrigerant leakage in the low-boiling refrigerant changes and decreases with respect to the composition at the time of design. The number of refills is counted such that the first time the refrigerant is replenished after the initial amount of refrigerant is filled is the first time, and it increases each time the refrigerant is replenished. By replenishing the refrigerant, the composition of the refrigerant at the time of leakage in the low-boiling refrigerant can be changed in a direction closer to the composition at the time of design.

[0049] On the other hand, if the composition of the refrigerant at the time of leakage has changed from the design composition, then when refrigerant of the design composition is replenished, the composition of the refrigerant after replenishment will still be different from the design composition. If the refrigerant charging operation is repeated in this state, even after charging, the composition of the low-boiling point refrigerant will decrease below the design composition, and the discrepancy between the composition of the low-boiling point refrigerant at the time of leakage and the design composition will increase. In particular, if the composition of the low-boiling point refrigerant increases in the design composition, the discrepancy between the composition of the low-boiling point refrigerant at the time of leakage and the design composition will increase accordingly.

[0050] <Refrigerant Charging Method> Figure 6 is a flowchart illustrating the process for determining the refrigerant charging method according to Embodiment 1. As shown in Figure 6, in the refrigeration cycle device 200, the refrigerant charging method is determined based on a comparison of the amount of refrigerant leakage and a specified value X. The amount of refrigerant leakage is the amount of refrigerant that has leaked from the refrigeration cycle device 200, and is the amount of refrigerant to be added to the refrigeration cycle device 200. The specified value X will be described later.

[0051] The process for determining the refrigerant charging method is performed prior to the refrigerant charging operation. The process for determining the refrigerant charging method may be configured to be started, for example, by instruction from a maintenance worker during maintenance. The process for determining the refrigerant charging method may also be configured to be started, for example, when the control device 210 periodically monitors the amount of refrigerant leakage and the amount of refrigerant leakage exceeds, for example, a threshold value. The threshold value is a value smaller than the specified value X.

[0052] The process of determining the refrigerant charging method is performed, for example, by the control device 210. When the process starts, the control device 210 first compares the amount of refrigerant leakage with a specified value X in step S01. If the control device 210 determines in step S01 that the amount of refrigerant leakage is greater than or equal to the specified value X (Yes in step S01), it proceeds to step S02. If it determines that the amount of refrigerant leakage is less than the specified value X (No in step S01), it proceeds to step S03.

[0053] Next, in step S02, the control device 210 determines the refrigerant charging method to be the first method, and in step S03, it determines the refrigerant charging method to be the second method and terminates the process. The control device 210 may also be configured to notify the external system of the refrigerant charging method determined in step S02 or step S03.

[0054] The first method of refrigerant charging involves recharging the refrigerant after all of the refrigerant sealed in the refrigeration cycle unit 200 has been recovered. After all of the refrigerant has been recovered and before the refrigerant is recharged, repairs such as fixing leaks are carried out in the refrigeration cycle unit 200. In the first method, refrigerant equivalent to the total amount sealed in the refrigeration cycle unit 200 is transported to the site where the charging work is performed, and the work is carried out there. According to the first method, since the refrigerant is recharged after all of it has been recovered, the refrigeration cycle unit 200 will be filled with the initial amount of refrigerant after recharging, and the composition of the refrigerant at the time of installation can be maintained.

[0055] The second method involves not recovering the refrigerant sealed in the refrigeration cycle unit 200, and instead replenishing the leaked refrigerant with it. In the second method, it is sufficient to transport refrigerant equivalent to the leaked amount to the site where the refilling work is performed and replenish it there. Since the entire amount of refrigerant is not recovered, the amount of refrigerant required is less than in the case of complete recovery, transportation of components such as cylinders becomes easier, and the preparation time can be shortened.

[0056] In this way, the refrigerant charging operation is carried out based on the judgment of the first method and the second method, so that the appropriate amount and composition ratio of refrigerant can be maintained, improving the reliability of the refrigeration cycle device 200 and enabling efficient operation.

[0057] Refrigerant leakage in the refrigeration cycle unit 200 is undesirable for both the refrigeration cycle unit 200 and the environment surrounding it. Therefore, after the second method is implemented, consideration is given to whether the refrigeration cycle unit 200 is in an undesirable state and whether it is within legally permissible limits, and a decision is made on whether or not to carry out repairs. If repairs are carried out, after the refrigerant is replenished in the refrigeration cycle unit 200 by the second method, for example, all the refrigerant is recovered, the leak is repaired, and then the refrigerant is refilled.

[0058] Thus, if the second method is selected, temporary measures can be taken during maintenance. Furthermore, if refrigerant is replenished using the second method, the refrigerant may not be recovered afterward. Instead, it may be collected in one location away from the leak, the leak may be repaired, and then the refrigerant circulation may be restarted. Additionally, by recovering and refilling the entire refrigerant after it has been replenished using the second method, a preparation period for refrigerant replenishment can be established. This helps to prevent the on-site environment from becoming excessively hot, cold, or humid during the repair period, thus reducing user comfort.

[0059] <Specified Value X> The specified value X is the ratio of the amount of refrigerant that has leaked to the amount of refrigerant initially filled into the device, and is a value designed based on the mixing rule and refrigerant mixing ratio determined by the combination of mixed refrigerants. The specified value X is a value calculated from the chemical potential of the refrigerant, i.e., fugacity, and can be calculated based on the following equations (1) to (3).

[0060]

[0061]

[0062]

[0063] Here, in equations 1 to 3 above, i: type of refrigerant, f: Fugacity Pa, f0: Standard state fugacity Pa, P: Pressure MPaA, Z: Vaporized composition wt%, y: Condensed composition wt%, φ: Fugacity coefficient, γ: Activity coefficient.

[0064] For example, R454B refrigerant and R454C refrigerant are non-azeotropic mixed refrigerants that are a mixture of R32 refrigerant, which is widely used in stationary air conditioners, and R1234yf refrigerant, which is used in small air conditioners installed in automobiles, etc. If the refrigerant composition of R454B is R32:R1234yf = 68.9:31.3 wt%, the specified value X can be calculated to be 25 to 35 wt%. If the refrigerant composition of R454B is R32:R1234yf = 21.5:78.5 wt%, the specified value X can be calculated to be 2 to 15 wt%.

[0065] The reason there is a range in the specified value X, which serves as an indicator of acceptable leakage, is that the relationship between the amount of refrigerant charged and the volume of the area in which the refrigerant can exist in the device differs depending on the system. Different systems result in a range in the amount of refrigerant charged relative to the total piping volume of the circuit. Furthermore, even within the same system, the amount of refrigerant charged relative to the volume differs depending on the design values, such as the target degree of subcooling. As a result, there is a range in the specified value X, which serves as an indicator of acceptable leakage.

[0066] By setting the amount of refrigerant leakage when the second method is implemented to less than the specified value X, the change in composition relative to the initial composition of the non-azeotropic mixed refrigerant can be reduced to, for example, 2 wt% or less, thus remaining within the error range for compositional change. The 2 wt% value for the error in compositional change is based on the permissible tolerance for mixed refrigerants indicated by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). The error in compositional change may vary depending on regional regulatory trends.

[0067] The refrigeration cycle device 200 is configured such that, if the amount of refrigerant leakage is less than a specified value X, at least for the first time, a second method is determined as the refrigerant charging method, and the refrigerant is replenished without being fully recovered. The specified value X can be calculated by characteristic calculation once the refrigerant to be charged is selected. After the first time the refrigerant is replenished using the second method, it may be replenished using the second method again, even for the second time and beyond, as long as it is within the allowable error range. Furthermore, even after the refrigerant has been replenished due to leakage in the second time and beyond, if it is judged that there is no problem from the standpoint of regulations or economic rationality, etc., a response of replenishment without full recovery may be chosen. For example, the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) currently allows for a variation of within 2 wt% from the nominal composition under current regulations. Therefore, even in the second time and beyond, if the error in composition change is satisfied as to keep it within 2 wt%, it is judged that it is more rational to replenish only the amount of leakage rather than fully recovering and recharging.

[0068] In the refrigeration cycle system 200, if the composition of the refrigerant changes from the composition at the time of design, a decrease in performance occurs in the refrigerant characteristics and the control of the refrigeration cycle system 200. In the refrigeration cycle system 200, each component is designed according to its refrigerant characteristics, i.e., latent heat and density, so if it deviates from the designed characteristics, a decrease in performance occurs. Specifically, the heat exchanger constituting the refrigeration cycle system 200 has a number of branches in the refrigerant flow path 7 determined according to the flow velocity and pressure loss corresponding to the latent heat of the refrigerant. If the refrigerant leaks and the composition of low-boiling-point refrigerant decreases and the composition of high-boiling-point refrigerant increases, the refrigerant density decreases, and when operated at a specific air conditioning capacity, the refrigerant flow velocity increases, the pressure loss increases, and the performance of the refrigeration cycle system 200 deteriorates.

[0069] Performance and quality can also deteriorate if the characteristics of the refrigerant assumed in the control of the refrigeration cycle device 200 deviate from the assumed range. Specifically, consider a case where the evaporator outlet is designed to be in a superheated state close to the saturation temperature, such as 3K, so that excessive liquid refrigerant does not flow into the compressor 14. In this case, even if the pressure and temperature conditions would result in superheated steam before the composition change, after the composition change, the superheat may increase to, for example, 5K or more due to the change in the characteristics of the refrigerant. When the superheat at the evaporator outlet increases, the two-phase region in the evaporator decreases, and energy efficiency decreases.

[0070] By implementing either the first method or the second method as the refrigerant charging method, the discrepancy between the composition of the low-boiling-point refrigerant at the time of leakage and the composition at the time of design can be suppressed, thereby suppressing a decrease in the performance or energy efficiency of the refrigeration cycle device 200.

[0071] Furthermore, the refrigerant that is fully recovered and refilled in the first method, or the refrigerant that is replenished in the second method, i.e., the refilled refrigerant, can have a composition that is higher in low-boiling-point refrigerant and lower in high-boiling-point refrigerant compared to the composition of the refrigerant initially sealed into the refrigeration cycle device 200. This makes it possible to return the composition of the refrigerant in the refrigeration cycle device 200, which has a reduced proportion of low-boiling-point refrigerant and a higher proportion of high-boiling-point refrigerant, back to the composition at the time of design.

[0072] The refrigerant charging method according to Embodiment 1 described above is configured such that either the first method or the second method is executed based on the amount of refrigerant leakage. The first method is a method in which the refrigerant is completely recovered and then recharged, while the second method is a method in which the refrigerant is not recovered but replenished. The first method allows the refrigerant composition to be returned to the design composition, thus enabling continued proper operation. The second method allows operation to be resumed early, thereby suppressing significant damage to user comfort and ensuring sufficient time for preparations such as repairs, or for preparing the refrigerant in cases where it is completely recovered and recharged after replenishment. By configuring the refrigerant charging method to be either the first method or the second method, changes in the refrigerant composition are reduced when a non-azeotropic mixed refrigerant is used, thereby achieving both improved quality and performance of the refrigeration cycle device 200.

[0073] Furthermore, the first method is performed when the amount of refrigerant leakage is equal to or greater than the specified value X, and the second method is performed when the amount of refrigerant leakage is less than the specified value X. Therefore, if the composition of the refrigerant at the time of leakage is within the margin of error for compositional change compared to the composition of the refrigerant at the time of design or installation, it is possible to deal with the situation by simply replenishing the refrigerant without complete recovery, which is economical and reduces the burden on the user.

[0074] Furthermore, if the amount is less than the specified value X, the second method will be executed at least once. Therefore, if the composition of the refrigerant at the time of leakage is within the margin of error for compositional change relative to the refrigerant composition after the first replenishment, it is possible to address the issue by simply refilling without complete recovery, even from the second time onward.

[0075] Furthermore, the specified value X is a value designed based on the mixing rule determined by the combination of mixed refrigerants and the mixing ratio of the refrigerants, and it is possible to determine whether to perform the first method or the second method based on the specified value X that is appropriate for the composition of the refrigerants.

[0076] Furthermore, if the refrigeration cycle device 200 is a multi-connection system, the amount of refrigerant charged increases, and the compositional changes due to leakage are amplified. Therefore, by implementing either the first method or the second method, it is possible to achieve both improved quality and improved performance.

[0077] The refrigerant is a non-azeotropic mixed refrigerant. Examples of non-azeotropic mixed refrigerants include olefin-based refrigerants containing tetrafluoropropene, ethylene-based refrigerants containing difluoroethylene, ethane-based refrigerants containing tetrafluoroethane, propane, and CO2. ２ It contains one or more of the following: , or dimethyl ether. Furthermore, the olefin-based refrigerant contains HFO1234yf or HFO1234ze(E).

[0078] Furthermore, since the composition of the refilled refrigerant has an increased proportion of low-boiling-point refrigerant that preferentially leaks compared to the non-azeotropic mixed refrigerant composition at the time of design, it is possible to return the composition of the refrigerant in the refrigeration cycle device 200, which has an increased proportion of high-boiling-point refrigerant, to the composition at the time of design.

[0079] Furthermore, in the refrigeration cycle device 200 according to Embodiment 1, the control device 210 is configured to determine whether the first method or the second method is executed based on the amount of refrigerant leakage and a specified value X. As a result, changes in the composition of the non-azeotropic mixed refrigerant in the refrigeration cycle device 200 are reduced, making it possible to achieve both improved quality and improved energy efficiency.

[0080] Embodiment 2. Figure 7 is a flowchart illustrating the process for determining the refrigerant charging method according to Embodiment 2. Embodiment 2 differs from Embodiment 1 in that the specified value X is determined by failure mode A. In Embodiment 2, parts common to Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiment 1. Failure mode A is an example of a failure mode.

[0081] As shown in Figure 7, in Embodiment 2, the refrigerant charging method is determined by the amount of refrigerant leakage, and either the first method or the second method is executed. Failure mode A is a mode in which the maximum operating capacity decreases and the refrigeration cycle device 200 fails to cool or heat properly. In the first method, when failure mode A occurs, i.e., when the maximum operating capacity decreases, all of the refrigerant in the refrigeration cycle device 200 is recovered and then recharged. In the second method, even if failure mode A does not occur, if a problem other than a decrease in capacity due to refrigerant leakage occurs and refrigerant replenishment is necessary, the required amount of refrigerant is replenished. By determining whether to use the first method or the second method based on failure mode A, changes in the refrigerant composition within the system can be suppressed, improving the quality and function of the refrigeration cycle device 200.

[0082] The process for determining the refrigerant charging method is performed by, for example, the control device 210, as in Embodiment 1. In step S11, the control device 210 determines whether or not failure mode A has occurred. If it determines that failure mode A has occurred (Yes in step S11), it proceeds to step S02, as in Figure 6, and determines the refrigerant charging method to be the first method. In step S11, if the control device 210 determines that failure mode A has not occurred (No in step S11), it proceeds to step S03, as in Figure 6, and determines the refrigerant charging method to be the second method.

[0083] In Embodiment 2, if it is determined that failure mode A has not occurred, the refrigeration cycle device 200 is configured to select the second method as the refrigerant charging method at least once, so that the refrigerant is replenished without being fully recovered. After the refrigerant has been replenished by the second method the first time, even for the second time and beyond, the refrigerant may be replenished by the second method if, for example, the reduction in maximum operating capacity is within an acceptable margin of error. Furthermore, even after the refrigerant has been replenished due to leakage in the second time and beyond, if it is determined that there is no problem from the standpoint of regulations or economic rationality, etc., a response of replenishment without full recovery may be selected.

[0084] Figure 8 is a graph showing the cooling capacity ratio to refrigerant leakage rate in the refrigeration cycle device 200 according to Embodiment 2. Figure 9 is a graph showing the heating capacity ratio to refrigerant leakage rate in the refrigeration cycle device 200 according to Embodiment 2.

[0085] As shown in Figures 8 and 9, in the refrigeration cycle device 200, if refrigerant leaks, the operating capacity gradually decreases, and the ratio of cooling capacity or heating capacity to the initial operating capacity decreases.

[0086] The decrease in operating capacity due to refrigerant leakage is not always linear. For example, in operation with excess refrigerant, the operating capacity will not decrease until the amount of refrigerant leakage equals the amount of excess refrigerant. Operation with excess refrigerant is a design consideration through control mechanisms.

[0087] If the amount of refrigerant leakage exceeds the amount of excess refrigerant, the amount of refrigerant required for operation will be insufficient, and the operating capacity will decrease. When the capacity decreases, even if the refrigeration cycle unit 200 is operating, the time it takes to reach the room air temperature required by the user will be extended, or the room air temperature may not reach the room air temperature required by the user due to heat load from outside, which may result in insufficient cooling or heating.

[0088] Therefore, if the maximum operating capacity of the refrigeration cycle unit 200 decreases and enough refrigerant leaks to cause insufficient cooling or heating in the refrigeration cycle unit 200, the compositional changes of the refrigerant will increase, potentially leading to a deterioration in the quality and function of the refrigeration cycle unit 200.

[0089] In Embodiment 2, the amount of refrigerant leakage is determined by failure mode A when deciding on the refrigerant charging method. Failure mode A is a failure mode in which the maximum operating capacity decreases and the refrigeration cycle device 200 fails to cool or heat properly. If failure mode A occurs, that is, if the maximum operating capacity decreases and failure to cool or heat properly occurs, the first method is selected, all of the refrigerant in the refrigeration cycle device 200 is recovered, and then it is recharged.

[0090] On the other hand, if the failure mode is not A, that is, if the maximum operating capacity is not reduced, or if there is no failure to cool or heat, and a problem other than a reduction in capacity due to refrigerant leakage occurs, the second method is selected and the necessary amount of refrigerant is replenished. By determining the amount of refrigerant leakage based on failure mode A and deciding on the first or second method, it is possible to suppress changes in the refrigerant composition within the system, thereby improving the quality and function of the refrigeration cycle device 200.

[0091] Furthermore, if the maximum operating capacity decreases, this can be defined as the maximum operating capacity falling to, for example, less than 10% of the initial maximum operating capacity. Also, if non-cooling or non-heating occurs, this can be defined as, for example, the time it takes to reach the user-set temperature being extended by 10% compared to the standard time.

[0092] According to the refrigerant charging method of Embodiment 2 described above, the amount of refrigerant leakage is determined by failure mode A, and either the first method or the second method is executed. Therefore, even in situations where it is difficult to determine the amount of refrigerant leakage, for example, if failure mode A occurs, it can be assumed that a specified value X or more of refrigerant has leaked, and refrigerant charging can be performed using the first method.

[0093] Furthermore, in failure mode A, if the maximum operating capacity of the refrigeration cycle unit 200 decreases and non-cooling or non-heating occurs, the first method is selected, allowing the refrigerant to be fully recovered and then refilled, restoring the refrigerant composition to the design composition.

[0094] Furthermore, if failure mode A does not occur, and at least the maximum operating capacity of the refrigeration cycle unit 200 does not decrease, or if there is no failure to cool or heat, the second method is selected, allowing the system to respond by simply replenishing the refrigerant without completely recovering it. This is economical and reduces the burden on the user.

[0095] Embodiment 3. Figure 10 is a flowchart illustrating the process for determining the refrigerant charging method according to Embodiment 3. Embodiment 3 differs from Embodiments 1 or 2 in that the specified value X is determined by failure mode B. In Embodiment 3, parts common to Embodiment 1 are denoted by the same reference numerals and their explanation is omitted, and the explanation will focus on the differences from Embodiments 1 or 2. Failure mode B is an example of a failure mode.

[0096] As shown in Figure 10, in Embodiment 3, the amount of refrigerant leakage is determined by failure mode B when determining the refrigerant charging method, and either the first method or the second method is executed. Failure mode B is, for example, the mode in which the refrigerant noise increases in the indoor expansion valve 21 of the indoor unit 202 during heating operation.

[0097] In the first method, if failure mode B occurs, that is, if the refrigerant noise increases in the indoor expansion valve 21 during heating operation, all of the refrigerant in the refrigeration cycle device 200 is recovered and then refilled. In the second method, if a problem other than a decrease in capacity due to refrigerant leakage occurs, but it is not failure mode A, the necessary amount of refrigerant is replenished when refrigerant replenishment is required. By determining whether to use the first or second method based on failure mode A, changes in the refrigerant composition within the system can be suppressed, improving the quality and function of the refrigeration cycle device 200.

[0098] The refrigerant charging method is performed by, for example, the control device 210, as in Embodiment 1 or 2. In step S21, the control device 210 determines whether or not failure mode B has occurred. If it determines that failure mode B has occurred (Yes in step S21), it proceeds to step S02, as in Figure 6, and determines the refrigerant charging method to be the first method. In step S21, if the control device 210 determines that failure mode B has not occurred (No in step S21), it proceeds to step S03, as in Figure 6, and determines the refrigerant charging method to be the second method.

[0099] Figure 11 is a graph showing the degree of subcooling at the outlet of the indoor heat exchanger 1 during cooling operation in a refrigeration cycle device 200 according to Embodiment 3, in relation to the amount of refrigerant leakage. As shown in Figure 11, in the refrigeration cycle device 200, if refrigerant leaks and the amount of refrigerant becomes insufficient, the degree of subcooling at the outlet of the indoor heat exchanger 1 decreases.

[0100] When the degree of supercooling at the outlet of the indoor heat exchanger 1 decreases, the refrigerant flowing into the indoor expansion valve 21 changes from a supercooled liquid refrigerant to a two-phase refrigerant, and the fluid noise in the indoor expansion valve 21 increases. During heating operation, the expansion of the refrigerant by the indoor expansion valve 21 generates fluid noise in the room, which degrades the quality of the refrigeration cycle device 200.

[0101] In Embodiment 3, the amount of refrigerant leakage is determined by failure mode B when determining the refrigerant charging method. Failure mode B is a failure mode that occurs when the refrigerant noise increases in the indoor expansion valve 21 during heating operation. If failure mode B occurs, that is, if the refrigerant noise increases in the indoor expansion valve 21 during heating operation, the first method is selected, all the refrigerant in the refrigeration cycle device 200 is recovered, and then recharged. If failure mode B does not occur, that is, if the refrigerant noise does not increase in the indoor throttling device during heating operation, the second method is selected, and the necessary amount of refrigerant is replenished. By determining the amount of refrigerant leakage by failure mode B, either the first or second method can be selected, which suppresses changes in the refrigerant composition within the system and improves the quality and function of the refrigeration cycle device 200.

[0102] Furthermore, a determination of whether the refrigerant noise has increased can be made, for example, if the refrigerant noise has increased by 10% or more compared to the initial refrigerant noise.

[0103] In the refrigerant charging method according to Embodiment 3 described above, the second method is executed when the refrigerant noise increases in the indoor expansion valve 21 during cooling operation. In other words, the increase in refrigerant noise is considered to indicate that the leakage amount is less than the specified value X, and the second method is executed at least once in which the refrigerant is refilled and replenished without being fully recovered. As a result, it becomes possible to control the change in refrigerant composition due to refrigerant leakage, thereby achieving both improved quality and energy efficiency of the refrigeration cycle device 200.

[0104] Embodiment 4. Figure 12 is a flowchart illustrating the process for determining the refrigerant charging method according to Embodiment 4. Embodiment 4 differs from Embodiments 1 to 3 in that the specified value X is determined by the failure mode C. In Embodiment 4, parts common to Embodiments 1 to 3 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiments 1 to 3.

[0105] As shown in Figure 12, in Embodiment 4, the refrigerant charging method determines whether the amount of refrigerant leakage is equal to the specified value X by failure mode C. Failure mode C is an example of a failure mode. Failure mode C is a failure mode that occurs when the current operating capacity of at least one of the multiple indoor unit 202 falls below the specified operating capacity. When failure mode C occurs, the amount of refrigerant leakage can be considered to be equal to or greater than the specified value X.

[0106] The refrigerant charging method is performed by, for example, the control device 210, as in Embodiments 1 to 3. In step S31, the control device 210 determines whether or not failure mode C has occurred. If it determines that failure mode C has occurred (Yes in step S31), it proceeds to step S02, as in Figure 6, and determines the refrigerant charging method to be the first method. In step S31, if the control device 210 determines that failure mode C has not occurred (No in step S31), it proceeds to step S03, as in Figure 6, and determines the refrigerant charging method to be the second method.

[0107] Figure 13 is a refrigerant circuit diagram of a refrigeration cycle device 200 according to Embodiment 4. As shown in Figure 13, the refrigeration cycle device 200 has a multi-type configuration in which a plurality of indoor unit units 202 are connected to an outdoor unit unit 201, and each of the plurality of indoor unit units 202 is provided with an indoor expansion valve 21.

[0108] Multiple indoor unit 202 are connected in parallel to each other by branch piping 70. The opening degree of the indoor expansion valve 21 is controlled by, for example, a control device 210 so that the refrigerant is divided in the branch piping 70 at a set flow rate.

[0109] During cooling operation, the refrigerant flowing out from the outdoor unit 201 expands in the indoor expansion valves 21 provided in each of the multiple indoor unit 202 and flows into the heat exchanger on the user side. The refrigerant flowing out from the high-pressure refrigerant outlet of the outdoor unit 201 is divided and distributed to each of the multiple indoor unit 202 by the branch pipe 70.

[0110] The refrigeration cycle device 200 is designed so that, during cooling operation, the refrigerant is subcooled and in a liquid state, and then diverted through the branch pipes 70. When the refrigerant is filled to the design level, it divertes in a liquid state through the branch pipes 70. Therefore, by adjusting the opening degree of the indoor expansion valve 21 in each of the multiple indoor unit units 202, the flow rate of the refrigerant diverted to each branch pipe 70 can be linearly controlled.

[0111] Figure 14 is a refrigerant circuit diagram illustrating the case of refrigerant leakage in the refrigeration cycle device 200 according to Embodiment 4. As shown in Figure 14, when the amount of refrigerant decreases due to refrigerant leakage, the refrigerant flowing through the branch pipe 70 becomes a gas-liquid two-phase state, and the cooling capacity of a specific indoor unit 202a among the multiple indoor unit units 202 decreases.

[0112] If the amount of refrigerant is lower than the amount charged at the time of design, gaseous and liquid two-phase refrigerant will flow into the branch pipe 70. The refrigerant separated in the two-phase region is separated mainly based on complex phenomena such as the inertia of the gaseous refrigerant, gravity of the liquid refrigerant, and the flow characteristics of the gas and liquid, so the relationship between the opening of the indoor expansion valve 21 and the amount of liquid refrigerant distributed becomes nonlinear. As a result, when gaseous and liquid two-phase refrigerant flows into the branch pipe 70, the flow rate of the separated refrigerant will fluctuate due to various factors, including the opening of the indoor expansion valve 21, the installation configuration of the branch pipe 70, or the length of the branch pipe 70.

[0113] Therefore, it becomes difficult to control the flow rate of the liquid refrigerant that should be diverted to the branch pipe 70, and for example, a large amount of gaseous refrigerant may be diverted to a particular indoor unit 202a, resulting in a decrease in cooling capacity. Consequently, if the cooling capacity decreases in at least one of the multiple indoor unit 202 during cooling operation, it can be considered that refrigerant is leaking.

[0114] Therefore, if the current operating capacity of a specific indoor unit 202a among the multiple indoor unit units 202 is lower than the specified operating capacity, it is assumed that the amount of refrigerant leakage is greater than or equal to the specified value X, and it is determined that failure mode C has occurred. In this case, the first method is selected as the refrigerant charging method, and all of the refrigerant in the refrigeration cycle device 200 is recovered by the first method and then recharged.

[0115] If the operating capacity of any of the multiple indoor unit 202 has not decreased compared to the specified operating capacity, the amount of refrigerant leakage is considered to be less than the specified value X, and it is determined that failure mode C has not occurred. In this case, the second method is selected as the refrigerant charging method, and the required amount of refrigerant is replenished. The required amount is the amount of refrigerant leakage, which is the amount of refrigerant needed to return to the refrigerant amount at the time of design. The second method is performed at least once when failure mode C has not occurred.

[0116] Thus, if at least one of the multiple indoor unit 202s becomes underperforming, the refrigerant is fully recovered and refilled by the first method. Furthermore, if none of the multiple indoor unit 202s have decreased in capacity relative to their specified operating capacity, the refrigerant is not fully recovered but replenished by the second method, at least for the first time. This makes it possible to suppress changes in the composition of the refrigerant in the refrigeration cycle device 200, improving the quality and function of the refrigeration cycle device 200 and maintaining user comfort.

[0117] According to the refrigerant charging method of Embodiment 4 described above, if the current operating capacity of at least one of the multiple indoor unit 202 is lower than the specified operating capacity, the first method is selected. If the current operating capacity of any of the multiple indoor unit 202 is not lower than the specified operating capacity, the second method is selected. In other words, if the current operating capacity of any of the multiple indoor unit 202 is equal to or greater than the specified operating capacity, the leakage amount is considered to be less than the specified value X, and the second method is executed at least once, in which the refrigerant is replenished without being fully recovered. As a result, it becomes possible to control the change in refrigerant composition due to refrigerant leakage, and even in a multi-type refrigeration cycle system 200, it is possible to achieve both improved quality and improved energy efficiency.

[0118] Embodiment 5. Figure 15 is a refrigerant circuit diagram of a refrigeration cycle device 200 according to Embodiment 5. Embodiment 5 differs from Embodiments 1 to 4 in that it has an outdoor expansion valve 22. In Embodiment 5, parts common to Embodiments 1 to 4 are denoted by the same reference numerals and their descriptions are omitted, and the explanation will focus on the differences from Embodiments 1 to 4.

[0119] As shown in Figure 15, the outdoor unit 201 of the refrigeration cycle device 200 is equipped with an outdoor expansion valve 22 for expanding the refrigerant. The outdoor expansion valve 22 is located upstream of the heat source side heat exchanger during heating operation, and its opening degree is controlled, for example, by a control device 210 during heating operation. By providing the outdoor expansion valve 22, the refrigerant, which has been reduced to a low temperature and low pressure by the outdoor expansion valve 22, can be allowed to flow into the heat source side heat exchanger while remaining in that low temperature and low pressure state, thereby improving air conditioning efficiency.

[0120] In the refrigeration cycle device 200 according to Embodiment 5, the refrigerant charging method is determined based on a comparison of the amount of refrigerant leakage with a specified value X, and the first or second fluid is replenished or refilled. The refrigerant charging method may be determined based on the operating capacity according to failure mode A or failure mode C. This makes it possible to suppress changes in the refrigerant composition within the refrigeration cycle device 200, thereby improving the quality and function of the refrigeration cycle device 200.

[0121] Figure 16 is a graph showing the degree of subcooling at the outlet of the indoor heat exchanger 1 during heating operation in relation to the amount of refrigerant leakage in the refrigeration cycle device 200 according to Embodiment 5. As shown in Figure 16, when the amount of refrigerant leakage increases and the amount of refrigerant decreases in the refrigeration cycle device 200, two-phase refrigerant flows into the outdoor expansion valve 22, similar to the indoor expansion valve 21, and noise is generated.

[0122] Therefore, in the refrigeration cycle device 200 according to Embodiment 5, the refrigerant charging method can be selected and determined based on failure mode B. In this case, failure mode B is the mode in which the refrigerant noise increases in the outdoor expansion valve 22 of the outdoor unit 201 during cooling operation. This makes it possible to suppress changes in the refrigerant composition within the refrigeration cycle device 200, thereby improving the quality and function of the refrigeration cycle device 200.

[0123] In Embodiment 5, a multi-type configuration having multiple indoor unit 202s is shown as the refrigeration cycle device 200. However, the refrigeration cycle device 200 may also have a configuration having a single indoor unit 202. In this case as well, the outdoor unit 201 is provided with an outdoor expansion valve 22, and the refrigerant charging method can be determined based on any of the failure modes A to C.

[0124] <Modification> Figure 17 is a refrigerant circuit diagram of a refrigeration cycle device 200 according to a modification of Embodiment 5. In Figure 17, the white arrows indicate the flow direction of the second fluid. As shown in Figure 17, the refrigeration cycle device 200 includes an outdoor unit 201, a plurality of indoor unit units 202, and a relay unit 203. The relay unit 203 is provided between the outdoor unit 201 and the plurality of indoor unit units 202. The outdoor unit 201 and the relay unit 203 are connected by a first connecting pipe 91 through which the first fluid flows. The first fluid is, for example, a non-azeotropic mixed refrigerant. The relay unit 203 and the plurality of indoor unit units 202 are connected by a second connecting pipe 92 through which the second fluid flows. The second fluid may be, for example, water or an antifreeze such as brine, or a different fluorocarbon refrigerant or natural refrigerant than the first fluid.

[0125] The relay unit 203 is equipped with a relay expansion valve 23, a relay heat exchanger 6, a pump 15, and multiple on-off valves 60 that switch the direction of refrigerant flow and the flow rate of refrigerant flowing through multiple indoor unit 202. The relay heat exchanger 6 is an example of a user-side heat exchanger. The relay expansion valve 23, the relay heat exchanger 6, the pump 15, and the flow path switching device 41 provided on the outdoor unit 201 are each shown in two, but they may also be provided one of each, or three or more, and are not particularly limited.

[0126] In the relay heat exchanger 6, the first fluid and the second fluid exchange heat, and the pump 15 transports the second fluid to each of the multiple indoor unit 202. The second fluid provides heating or cooling to the space where the multiple indoor unit 202 are located.

[0127] In the modified refrigeration cycle device 200, either the first method or the second method is determined as the refrigerant charging method based on a comparison of the amount of refrigerant leakage with a specified value X, and the first fluid or the second fluid is replenished or refilled. The determination of the refrigerant charging method may be made based on any of failure modes A to C. This makes it possible to suppress changes in the refrigerant composition of the first fluid or the second fluid, thereby improving the quality and function of the refrigeration cycle device 200.

[0128] Furthermore, at least one of the first and second fluids should be a non-azeotropic refrigerant mixture.

[0129] According to the refrigeration cycle device 200 of Embodiment 5 described above, the outdoor unit 201 is equipped with an outdoor expansion valve 22, and during heating operation, if the refrigerant noise increases in the outdoor expansion valve 22, a second method is performed in which the refrigerant is refilled without being fully recovered at least once. This makes it possible to control changes in the refrigerant composition due to refrigerant leakage, thereby improving both the quality and energy efficiency of the refrigeration cycle device 200.

[0130] Embodiments 1 to 5 can be combined as appropriate. That is, for example, the configuration may be such that the refrigerant is fully recovered and refilled when any of failure modes A to C are met, or when any two of them are met, and the combination is not particularly limited. Furthermore, Embodiments 1 to 5 do not limit the circuit configuration as long as a non-azeotropic mixed refrigerant is used. The circuit configuration may also be such that it has multiple indoor unit units 202, or multiple outdoor unit units 201, and is not particularly limited. Moreover, when the system contains a first fluid and a second fluid different from the first fluid, the refrigerant charging method of this disclosure is applicable as long as at least one of them is a non-azeotropic mixed refrigerant.

[0131] 1 Indoor heat exchanger, 4 Outdoor heat exchanger, 5 Outdoor fan, 6 Repeater heat exchanger, 7 Refrigerant flow path, 13 Accumulator, 14 Compressor, 15 Pump, 18 Indoor fan, 21 Indoor expansion valve, 22 Outdoor expansion valve, 23 Repeater expansion valve, 32 Cylinder, 34 Three-way valve, 40 On / off valve, 41 Flow path switching device, 60 On / off valve, 70 Branch piping, 91 First connecting piping, 92 Second connecting piping, 200 Refrigeration cycle device, 201 Outdoor unit, 202 Indoor unit, 202a Specific indoor unit, 203 Repeater unit, 210 Control device.

Claims

1. In a refrigeration cycle device that uses a non-azeotropic mixed refrigerant, which is a mixture of two or more refrigerants with different boiling points, if the non-azeotropic mixed refrigerant leaks, a refrigerant charging method is performed by either a first method in which the non-azeotropic mixed refrigerant is fully recovered and then refilled based on the amount of leakage of the non-azeotropic mixed refrigerant, or a second method in which the non-azeotropic mixed refrigerant is replenished without being recovered.

2. The refrigerant charging method according to claim 1, wherein the first method is performed when the amount of leakage is equal to or greater than a specified value, and the second method is performed when the amount of leakage is less than the specified value.

3. The refrigerant charging method according to claim 2, wherein if the amount of leakage is less than the specified value, the second method is performed at least once.

4. The refrigerant charging method according to claim 2 or 3, wherein the specified value is a value designed based on a mixing rule determined by the combination of mixed refrigerants and the mixing ratio of the refrigerants.

5. The refrigerant charging method according to any one of claims 1 to 4, wherein the amount of leakage of the non-azeotropic mixed refrigerant is determined by the failure mode of the refrigeration cycle device, and either the first method or the second method is performed.

6. The refrigerant charging method according to claim 5, wherein, in the determination based on the failure mode, the first method is selected when the maximum operating capacity of the refrigeration cycle device decreases and non-cooling or non-heating occurs.

7. The refrigerant charging method according to claim 5 or 6, wherein, in the determination based on the failure mode, the second method is selected if, at least, the maximum operating capacity of the refrigeration cycle device does not decrease, or if no cooling or heating occurs.

8. The refrigerant charging method according to any one of claims 1 to 7, wherein the refrigeration cycle device is equipped with an indoor expansion valve, and the second method is selected when the refrigerant noise from the indoor expansion valve increases at least once during heating operation of the refrigeration cycle device.

9. The refrigerant charging method according to any one of claims 1 to 8, wherein the refrigeration cycle device is equipped with an outdoor expansion valve, and the second method is selected when the refrigerant noise from the outdoor expansion valve increases at least once during cooling operation of the refrigeration cycle device.

10. The refrigerant charging method according to any one of claims 1 to 9, wherein the refrigeration cycle device is a multi-connection system in which two or more indoor units are connected.

11. The refrigerant charging method according to any one of claims 1 to 9, wherein the refrigeration cycle device is configured such that at least two indoor units are connected to an outdoor unit, and when cooling operation is being performed in the refrigeration cycle device, the second method is selected in which the non-azeotropic mixed refrigerant is not fully recovered but refilled when the operating capacity of at least one of the indoor units is less than the specified operating capacity.

12. The non-azeotropic mixed refrigerant includes olefin-based refrigerants containing tetrafluoropropene, ethylene-based refrigerants containing difluoroethylene, ethane-based refrigerants containing tetrafluoroethane, propane, CO2 ２ A refrigerant charging method according to any one of claims 1 to 11, comprising one or more of the following: , or dimethyl ether, wherein the olefin-based refrigerant comprises HFO1234yf or HFO1234ze(E).

13. The refrigerant charging method according to any one of claims 1 to 12, wherein the non-azeotropic mixed refrigerant comprises a low-boiling point refrigerant and a high-boiling point refrigerant with a higher boiling point than the low-boiling point refrigerant, and the composition of the non-azeotropic mixed refrigerant to be refilled is such that the proportion of the low-boiling point refrigerant is increased compared to the composition of the non-azeotropic mixed refrigerant at the time of design of the refrigeration cycle device.

14. A refrigeration cycle device comprising: a heat source side heat exchanger and a utilization side heat exchanger connected in a ring by refrigerant piping, a refrigerant circuit through which a non-azeotropic mixed refrigerant, which is a mixture of two or more refrigerants with different boiling points, circulates; and a control device for controlling the refrigerant circuit, wherein the control device determines whether the leakage amount of the non-azeotropic mixed refrigerant is greater than or equal to a specified value; if the leakage amount is greater than or equal to the specified value, it determines and notifies a first method of recovering all of the non-azeotropic mixed refrigerant and then refilling the non-azeotropic mixed refrigerant; and if the leakage amount is less than the specified value, it determines and notifies a second method of supplementing the non-azeotropic mixed refrigerant without recovering it.

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