Refrigeration cycle device

Abstract

Provided is a highly reliable refrigeration cycle device. The refrigeration cycle device (100) comprises a refrigerant circuit (Q1) obtained by sequentially connecting a compressor (1), a heat source-side heat exchanger (3), a receiver (5), an expansion valve (7), and a load-side heat exchanger (8) in an annular shape. The refrigerant sealed in the refrigerant circuit (Q1) is a non-azeotropic refrigerant mixture including a first refrigerant capable of causing a disproportionation reaction and a second refrigerant having a lower saturation pressure than the first refrigerant. The refrigeration cycle device (100) further comprises: a first pipe (K1) that sequentially guides the refrigerant from the receiver (5) to the compressor (1) via the expansion valve (7) and the load-side heat exchanger (8); and a second pipe (K2) of which one end is connected to the receiver (5) and the other end is connected to the first pipe (K1).

Description

Refrigeration cycle equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] A known technique for suppressing the disproportionation reaction of a refrigerant is described in, for example, Patent Document 1. Patent Document 1 describes that when the refrigerant pressure on the high-pressure side of a refrigerant circuit reaches a third value, power supply to an electric element of a compressor is stopped.

[0003] Japanese Patent Application Laid-Open No. 2018-112396

[0004] In the technology described in Patent Document 1, the disproportionation reaction of the refrigerant is suppressed by stopping the supply of power to the electric element of the compressor, but there is room for further improvement in the reliability of the refrigeration cycle device.

[0005] Therefore, an object of the present disclosure is to provide a highly reliable refrigeration cycle device.

[0006] In order to solve the above-mentioned problems, the refrigeration cycle device according to the present disclosure includes a refrigerant circuit in which a compressor, a heat source side heat exchanger, a receiver, an expansion mechanism, and a load side heat exchanger are connected in sequence in a ring, and the refrigerant sealed in the refrigerant circuit is a non-azeotropic refrigerant mixture containing a first refrigerant in which a disproportionation reaction can occur and a second refrigerant having a lower saturation pressure than the first refrigerant, and further includes a first pipe that guides the refrigerant from the receiver to the compressor via the expansion mechanism and the load side heat exchanger in sequence, and a second pipe having one end connected to the receiver and the other end connected to the first pipe.

[0007] According to the present disclosure, a highly reliable refrigeration cycle device can be provided.

[0008] Fig. 1 is a configuration diagram of a refrigeration cycle device according to a first embodiment. Fig. 2 is an explanatory diagram including a receiver, a first pipe, and a second pipe provided in the refrigeration cycle device according to the first embodiment. Fig. 3 is a characteristic diagram showing the relationship between the dryness fraction of a refrigerant and the concentration of disproportionated components in the gas phase in the refrigeration cycle device according to the first embodiment. Fig. 4 is an explanatory diagram including a receiver, a first pipe, and a second pipe provided in a refrigeration cycle device according to a first modified embodiment. Fig. 5 is an explanatory diagram including a receiver, a first pipe, and a second pipe provided in a refrigeration cycle device according to a second modified embodiment. Fig. 6 is a configuration diagram of a refrigeration cycle device according to a third embodiment.

[0009] First Embodiment Configuration of Refrigeration Cycle Apparatus Fig. 1 is a configuration diagram of a refrigeration cycle apparatus 100 according to a first embodiment. Note that arrows in Fig. 1 indicate the direction of refrigerant flow. The refrigeration cycle apparatus 100 shown in Fig. 1 is an apparatus that performs refrigeration and air conditioning by circulating a refrigerant in a refrigeration cycle (heat pump cycle) in a refrigerant circuit Q1. Note that the refrigerant sealed in the refrigerant circuit Q1 is a non-azeotropic refrigerant mixture (a mixture of refrigerants with different boiling points) that includes a first refrigerant in which a disproportionation reaction can occur and a second refrigerant having a lower saturation pressure than the first refrigerant.

[0010] As the first refrigerant, for example, the following can be used (refrigerant numbers are shown in parentheses). That is, trans-1,2-difluoroethylene (R1132(E)) and 1,1,2-trifluoroethylene (R1123) can be used as the first refrigerant. Other refrigerants that can be used include cis-1,2-difluoroethylene (R1132(Z)) and 1,1-difluoroethylene (R1132a). These first refrigerants have the advantage of having an extremely low global warming potential (GWP).

[0011] The first refrigerant is also called a high-pressure refrigerant because it has a relatively high saturation pressure (i.e., a low boiling point and therefore a high evaporation rate). The inclusion of the first refrigerant in the refrigerant circuit Q1 reduces pressure loss during refrigeration and ensures an enthalpy difference in the refrigeration cycle.

[0012] On the other hand, a disproportionation reaction may occur in the first refrigerant under certain conditions. Here, the "disproportionation reaction" refers to a phenomenon in which, when a certain amount of ignition energy is applied in a high-temperature, high-pressure environment, a certain reaction proceeds in a chain reaction, generating a large amount of reaction heat and a sudden increase in pressure.

[0013] The second refrigerant described above has a lower saturation pressure than the first refrigerant (i.e., it has a higher boiling point and is less likely to evaporate), and is therefore also referred to as a low-pressure refrigerant. Examples of such second refrigerants include the following (refrigerant numbers are shown in parentheses). Specifically, 2,3,3,3-tetrafluoropropene (R1234yf) is used as the second refrigerant. Other examples of second refrigerants that may be used include difluoromethane (R32), trans-1,3,3,3-tetrafluoropropene (R1234ze(E)), and cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)).

[0014] These second refrigerants also have the advantage of having extremely low global warming potential (GWP). In addition, by including the second refrigerant in the refrigerant circuit Q1, the occurrence of disproportionation reactions can be suppressed compared to when the first refrigerant is used alone.

[0015] 1 is used as, for example, a refrigerator, but is not limited to this. That is, the refrigeration cycle apparatus 100 can be applied to air conditioners such as multi-air conditioners for buildings, package air conditioners, and room air conditioners, as well as water heaters, air-conditioning water heaters, and chillers.

[0016] 1 , the refrigeration cycle apparatus 100 includes a compressor 1, a check valve 2, a heat source side heat exchanger 3, a first fan 4, a receiver 5, a shutoff valve 6, an expansion valve 7 (expansion mechanism), a load side heat exchanger 8, and a second fan 9. In addition to the above-described components, the refrigeration cycle apparatus 100 also includes a pipe K0, a first pipe K1, a second pipe K2, an on-off valve 11, a discharge pressure sensor 12, and a control unit 13.

[0017] The refrigerant circuit Q1 is configured by sequentially connecting a compressor 1, a heat source side heat exchanger 3, a receiver 5, an expansion valve 7 (expansion mechanism), and a load side heat exchanger 8 in a ring shape. The refrigerant circulates in the refrigeration cycle (heat pump cycle) in the refrigerant circuit Q1.

[0018] The compressor 1 is a device that compresses a low-temperature, low-pressure gas refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. For example, a scroll compressor or a rotary compressor is used as this compressor 1. Although not shown in Figure 1, an accumulator is connected to the suction side of the compressor 1 for separating the refrigerant into gas and liquid.

[0019] The check valve 2 is a valve for preventing backflow of the refrigerant and is provided on the discharge side of the compressor 1. The check valve 2 allows the refrigerant to flow from the compressor 1 toward the heat source-side heat exchanger 3, while prohibiting reverse flow. The heat source-side heat exchanger 3 is a heat exchanger (condenser) that exchanges heat between the high-temperature, high-pressure refrigerant discharged from the compressor 1 and outside air sent in by a first fan 4. The first fan 4 is a fan that sends outside air into the heat source-side heat exchanger 3 and is provided near the heat source-side heat exchanger 3.

[0020] The receiver 5 is a tank that stores excess refrigerant, and is connected via a pipe K0 to the downstream side of the heat source side heat exchanger 3. The shutoff valve 6 is a solenoid valve that is closed during the refrigerant recovery operation, and is provided in the first pipe K1 between the receiver 5 and the expansion valve 7 (expansion mechanism).

[0021] The refrigerant recovery operation is an operation in which, when normal refrigeration cycle operation is stopped, refrigerant from the load side, such as the load side heat exchanger 8, is moved to the heat source side heat exchanger 3 and the receiver 5 and recovered while driving the compressor 1. By performing such a refrigerant recovery operation, refrigerant is recovered in the heat source side heat exchanger 3 and the receiver 5, as shown in the dashed line area S1 in Fig. 1. As a result, it is possible to prevent a large amount of liquid refrigerant from being sucked into the compressor 1 at the start of the next operation. Incidentally, the shutoff valve 6 is maintained in a closed state during the refrigerant recovery operation, but is maintained in an open state during normal refrigeration cycle operation.

[0022] The expansion valve 7 shown in Fig. 1 is a valve that reduces the pressure of the refrigerant condensed in the heat source-side heat exchanger 3. The load-side heat exchanger 8 is a heat exchanger (evaporator) that exchanges heat between the refrigerant flowing through its heat transfer tubes (not shown) and the air (air in the space to be air-conditioned) sent from a second fan 9. The second fan 9 is a fan that sends air to the load-side heat exchanger 8 and is installed near the load-side heat exchanger 8. The air cooled by the heat exchange with the refrigerant in the load-side heat exchanger 8 is then blown out into the space to be air-conditioned.

[0023] 1 is a pipe that guides refrigerant from the receiver 5 to the compressor 1 via an expansion valve 7 (expansion mechanism) and a load-side heat exchanger 8. The upstream end of the first pipe K1 is connected to the bottom of the receiver 5. The downstream end of the first pipe K1 is connected to the suction side of the compressor 1.

[0024] The second pipe K2 shown in FIG. 1 is a pipe for preventing an excessive amount of liquid refrigerant from accumulating in the receiver 5. In the example of FIG. 1, the second pipe K2 includes a horizontal section extending horizontally from its upstream end and a vertical section extending vertically downward from the downstream end of the horizontal section. One end (upstream end) of the second pipe K2 is connected to a side surface of the receiver 5. More specifically, the one end of the second pipe K2 is connected to a position at a predetermined height relative to the bottom of the receiver 5. The other end (downstream end) of the second pipe K2 is connected to the first pipe K1. More specifically, the other end of the second pipe K2 is connected to the first pipe K1 between the receiver 5 and the shutoff valve 6.

[0025] The on-off valve 11 is a solenoid valve that is opened appropriately during refrigerant recovery operation and is provided in the second pipe K2. Note that the on-off valve 11 is maintained in a closed state during normal refrigeration cycle operation. The discharge pressure sensor 12 is a sensor that detects the discharge pressure of the compressor 1 and is provided on the discharge side of the compressor 1 (between the compressor 1 and the check valve 2 in the example of FIG. 1). The momentarily detected value of the discharge pressure sensor 12 is output to the control unit 13.

[0026] Although not shown in the figure, the control unit 13 has a hardware configuration including electronic circuits such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces. The CPU reads out programs stored in the ROM and loads them into the RAM, causing the CPU to execute various processes. The control unit 13 controls the compressor 1, the first fan 4, the shutoff valve 6, the expansion valve 7, the second fan 9, the on-off valve 11, and other components in a predetermined manner. The processing of the control unit 13 will be described later.

[0027] Fig. 2 is an explanatory diagram including the receiver 5, the first pipe K1, and the second pipe K2. In the example of Fig. 2, a pipe K0 is inserted into the top of the receiver 5. The pipe K0 is a pipe that guides the refrigerant condensed in the heat source side heat exchanger 3 (see Fig. 1) to the receiver 5. In addition, a first pipe K1 is inserted into the bottom of the receiver 5. The refrigerant is guided from the receiver 5 to the expansion valve 7 (see Fig. 1) via this first pipe K1.

[0028] Further, a second pipe K2 is inserted into a predetermined position on the side surface of the receiver 5. Specifically, the second pipe K2 is inserted horizontally at a position at a predetermined height h relative to the bottom of the receiver 5. The second pipe K2 has the function of preventing an excessive amount of liquid refrigerant from accumulating in the receiver 5.

[0029] <Regarding the Disproportionation Reaction> As described above, the refrigerant sealed in the refrigerant circuit Q1 (see FIG. 1) is a non-azeotropic refrigerant mixture containing a first refrigerant and a second refrigerant. The first refrigerant is a high-pressure refrigerant with a low boiling point that evaporates easily. On the other hand, the second refrigerant is a low-pressure refrigerant with a high boiling point that evaporates less easily. Note that the greater the amount of liquid refrigerant stored in the region from compressor 1 to shutoff valve 6, the higher the concentration of the gaseous first refrigerant due to the difference in boiling points described above. This makes it more likely that a disproportionation reaction will occur in the first refrigerant the next time compressor 1 is started.

[0030] In the refrigerant recovery operation, as shown in area S1 in Fig. 1, the refrigerant is recovered in the heat source side heat exchanger 3 and the receiver 5. In this case, if a large amount of refrigerant is recovered in a small area, the first refrigerant evaporates more easily than the second refrigerant, and therefore the concentration of the gaseous first refrigerant increases, making it more likely that a disproportionation reaction will occur in the first refrigerant.

[0031] Fig. 3 is a characteristic diagram showing the relationship between the quality fraction of a refrigerant and the concentration of disproportionated components in the gas phase (see also Fig. 1 as appropriate). The horizontal axis in Fig. 3 represents the quality fraction of the refrigerant inside the system. Here, the quality fraction of a refrigerant is the ratio of the mass of dry vapor refrigerant to the mass of vapor refrigerant. For example, if all the vapor refrigerant present inside the system is wet vapor, the quality fraction value is 0. On the other hand, if all the vapor refrigerant present inside the system is dry vapor, the quality fraction value is 1.

[0032] The vertical axis in Fig. 3 represents the concentration of disproportionation components in the gas phase present inside the system. In other words, the concentration of disproportionation components in the gas phase is the proportion (mass percent concentration) of the gaseous first refrigerant that can undergo a disproportionation reaction in the gas refrigerant present inside the system. Line L1 in Fig. 3 is a line that shows the relationship between the quality fraction and the concentration of disproportionation components in the gas phase.

[0033] For example, the greater the amount of liquid refrigerant stored in the system, the greater the amount of the first refrigerant that evaporates as wet vapor, resulting in a lower dryness fraction of the refrigerant within the system. Furthermore, as shown by line L1, the lower the dryness fraction of the refrigerant within the system, the higher the concentration of disproportionation components in the gas phase (the concentration of the gaseous first refrigerant). In other words, the greater the amount of liquid refrigerant stored in receiver 5, the higher the concentration of the gaseous first refrigerant within the system, making the disproportionation reaction more likely to occur in the first refrigerant.

[0034] Therefore, in the first embodiment, the control unit 13 (see Figure 1) opens the on-off valve 11 (see Figure 1) while the refrigerant recovery operation is being performed, and when the detection value of the discharge pressure sensor 12 (see Figure 1) reaches a predetermined value, the refrigerant recovery operation is stopped.

[0035] First, the refrigerant circuit operation will be described with reference to FIG. 1 . As described above, the refrigerant recovery operation is an operation for recovering refrigerant from the load side to the heat source side, and is performed when normal refrigeration cycle operation is stopped. Specifically, during the refrigerant recovery operation, the control unit 13 drives the compressor 1 while maintaining the shutoff valve 6 in a closed state. This allows refrigerant to be recovered from the load side (such as the load-side heat exchanger 8) of the refrigerant circuit Q1 to the heat source side (such as the heat-source-side heat exchanger 3 and receiver 5). Furthermore, because the shutoff valve 6 is closed (i.e., the downstream side of the receiver 5 is blocked), the liquid refrigerant level in the receiver 5 rises as the refrigerant recovery operation progresses.

[0036] Furthermore, the control unit 13 appropriately opens the on-off valve 11 while the refrigerant recovery operation is being performed. For example, the control unit 13 opens the on-off valve 11 when a predetermined time has elapsed since the start of the refrigerant recovery operation. Note that the on-off valve 11 may be opened from the start of the refrigerant recovery operation. When the on-off valve 11 is opened in this manner, it becomes possible to store an excess amount of liquid refrigerant by the volume of the second pipe K2 (at least the volume upstream of the on-off valve 11) compared to when the on-off valve 11 is closed.

[0037] For example, suppose that after the on-off valve 11 is opened, the liquid level of the liquid refrigerant rises to the height of the upstream end (opening) of the second pipe K2 in the receiver 5. If the liquid refrigerant continues to flow into the receiver 5 from this state, the liquid refrigerant flows into the second pipe K2 under its own weight and is stored inside the second pipe K2. Therefore, until the second pipe K2 is filled with liquid refrigerant, the liquid level of the liquid refrigerant in the receiver 5 is maintained at the height of the upstream end of the second pipe K2. In other words, the amount of liquid refrigerant stored in the receiver 5 is maintained at a predetermined volume determined by the height of the upstream end of the second pipe K2. This prevents the concentration of the gaseous first refrigerant from becoming too high inside the system, and ultimately prevents the occurrence of a disproportionation reaction.

[0038] After the on-off valve 11 opens, as the refrigerant recovery operation progresses further while the liquid level of the liquid refrigerant in the receiver 5 is maintained at the height position of the upstream end of the second pipe K2, the pressure of the refrigerant in the heat source side heat exchanger 3 increases, and accordingly, the detection value of the discharge pressure sensor 12 also increases.

[0039] Then, when the detection value of the discharge pressure sensor 12 reaches a predetermined value after the on-off valve 11 is opened, the control unit 13 stops the compressor 1 to stop the refrigerant recovery operation and closes the on-off valve 11. The "predetermined value" is a pressure threshold that serves as a criterion for determining whether to stop the refrigerant recovery operation and is set in advance. For example, the "predetermined value" is set so that the inside of the second pipe K2 is filled with liquid refrigerant and the liquid level of the liquid refrigerant in the receiver 5 does not greatly exceed the height position of the upstream end of the second pipe K2.

[0040] <Effects> According to the first embodiment, the control unit 13 opens the on-off valve 11 while the refrigerant recovery operation is being performed. This allows the second pipe K2 to store liquid refrigerant, thereby preventing an excessive amount of liquid refrigerant from being stored in the receiver 5. As a result, the concentration of the gaseous first refrigerant is less likely to increase inside the system, thereby preventing a disproportionation reaction from occurring in the first refrigerant at the next startup. Furthermore, when the detection value of the discharge pressure sensor 12 reaches a predetermined value, the control unit 13 stops the refrigerant recovery operation. This prevents the liquid level in the receiver 5 from further rising when the second pipe K2 is filled with liquid refrigerant. As such, according to the first embodiment, a highly reliable refrigeration cycle apparatus 100 can be provided.

[0041] In addition, in the first embodiment, the configuration of the refrigeration cycle apparatus 100 is relatively simple, which reduces the manufacturing cost of the refrigeration cycle apparatus 100. Furthermore, the processing of the control unit 13 when performing the refrigerant recovery operation is also simple, which reduces the processing load of the control unit 13.

[0042] <First Modification> Fig. 4 is an explanatory diagram including the receiver 5, the first pipe K1, and the second pipe K2a provided in a refrigeration cycle apparatus according to a first modification. As shown in Fig. 4, the second pipe K2a may be inserted vertically from the bottom of the receiver 5. The second pipe K2a is configured to allow liquid refrigerant whose liquid level relative to the bottom of the receiver 5 is equal to or higher than a predetermined height h to flow out of the receiver 5. Even with this configuration, the same effects as those of the first embodiment can be achieved.

[0043] <Second Modification> Fig. 5 is an explanatory diagram including the receiver 5, the first pipe K1, and the second pipe K2b provided in a refrigeration cycle apparatus according to a second modification. As shown in Fig. 5, the second pipe K2b may be inserted vertically from the top of the receiver 5. The second pipe K2b is configured to allow liquid refrigerant to flow out of the receiver 5 when the liquid level relative to the bottom of the receiver 5 is equal to or higher than a predetermined height h. This configuration also achieves the same effects as the first embodiment. Note that because the refrigerant rises due to a pressure difference through the vertical portion of the second pipe K2b, the configuration shown in Fig. 5 does not particularly pose a risk of refrigerant flow being impaired.

[0044] Second Embodiment The second embodiment differs from the first embodiment in that the downstream end of the second pipe K2c (see FIG. 6) is connected to the downstream side of the shutoff valve 6 (see FIG. 6) in the first pipe K1 (see FIG. 6). The second embodiment also differs from the first embodiment in that there is no particular need to use the detection value of the discharge pressure sensor 12 (see FIG. 6) when stopping the refrigerant recovery operation. The second embodiment is otherwise similar to the first embodiment. Therefore, only the differences from the first embodiment will be described, and a description of the overlapping parts will be omitted.

[0045] Fig. 6 is a configuration diagram of a refrigeration cycle apparatus 100A according to a second embodiment. As shown in Fig. 6, the refrigeration cycle apparatus 100A includes a second pipe K2c and an on-off valve 11. One end (upstream end) of the second pipe K2c is connected to a predetermined location on the side surface of the receiver 5. That is, the second pipe K2 is connected so that the height position of the upstream end (opening) of the second pipe K2c is at a predetermined height with respect to the bottom of the receiver 5.

[0046] The other end (downstream end) of the second pipe K2c is connected to the first pipe K1. More specifically, the other end (downstream end) of the second pipe K2 is connected to the first pipe K1 between the shutoff valve 6 and the expansion valve 7 (expansion mechanism). As shown in Fig. 6, the second pipe K2c is provided with an on-off valve 11. The on-off valve 11 is an electromagnetic valve that is opened as appropriate during the refrigerant recovery operation.

[0047] The control unit 13 opens the on-off valve 11 while keeping the shutoff valve 6 closed during the refrigerant recovery operation. For example, the control unit 13 opens the on-off valve 11 for a predetermined time after the start of the refrigerant recovery operation. The predetermined time is set in advance so that the liquid refrigerant level in the receiver 5 is maintained at or below the level of the upstream end of the second pipe K2c. Note that the on-off valve 11 may be kept open from the start to the end of the refrigerant recovery operation.

[0048] As described above, the downstream end of the second pipe K2c is connected downstream of the shutoff valve 6. Therefore, when the on-off valve 11 is opened during the refrigerant recovery operation, the liquid refrigerant flowing from the receiver 5 through the second pipe K2c is guided to the first pipe K1 downstream of the shutoff valve 6. This makes it possible to keep the liquid level of the liquid refrigerant in the receiver 5 below the height of the upstream end of the second pipe K2c.

[0049] During the refrigerant recovery operation, the expansion valve 7 may be maintained in either a closed state or an open state. Even when the expansion valve 7 is closed, liquid refrigerant can be stored in the first pipe K1 between the shutoff valve 6 in a closed state and the expansion valve 7 in a closed state, and liquid refrigerant can also be stored inside the second pipe K2c. Furthermore, when the expansion valve 7 is open at a predetermined opening, excess refrigerant that flows out via the second pipe K2c can be circulated appropriately in the refrigerant circuit Q1.

[0050] <Effects> According to the second embodiment, the downstream end of the second pipe K2c is connected between the shutoff valve 6 and the expansion valve 7. Therefore, by the control unit 13 opening the on-off valve 11 during the refrigerant recovery operation, the liquid level of the liquid refrigerant stored in the receiver 5 can be kept below the height of the upstream end of the second pipe K2c. This prevents the concentration of the gaseous first refrigerant from increasing inside the system, and ultimately prevents the occurrence of a disproportionation reaction.

[0051] Third Embodiment In the third embodiment, instead of the second pipe K2 (see FIG. 1) described in the first embodiment, a second pipe K2d (see FIG. 7) is provided to guide the refrigerant from the receiver 5 (see FIG. 7) to the suction side of the compressor 1 (see FIG. 7). In addition, in the third embodiment, an on-off valve 14 (see FIG. 7), a capillary tube 15 (see FIG. 7), and a temperature sensor 16 (see FIG. 7) are provided in the second pipe K2d (see FIG. 7). Note that the rest is the same as in the first embodiment. Therefore, only the parts that are different from the first embodiment will be described, and a description of the overlapping parts will be omitted.

[0052] Fig. 7 is a configuration diagram of a refrigeration cycle apparatus 100B according to a third embodiment. As shown in Fig. 7, the refrigeration cycle apparatus 100B includes a compressor 1, a check valve 2, a heat source-side heat exchanger 3, a first fan 4, a receiver 5, a shutoff valve 6, an expansion valve 7 (expansion mechanism), a load-side heat exchanger 8, and a second fan 9. In addition to the above-described components, the refrigeration cycle apparatus 100B also includes a first pipe K1, a second pipe K2d, a control unit 13, an on-off valve 14, a capillary tube 15, and a temperature sensor 16.

[0053] The second pipe K2d is a pipe for preventing an excessive amount of liquid refrigerant from being stored in the receiver 5. One end (upstream end) of the second pipe K2d is inserted into the side surface of the receiver 5 so that its height position relative to the bottom of the receiver 5 is a predetermined height. The other end (downstream end) of the second pipe K2d is connected to the suction side of the compressor 1 in the first pipe K1. Note that a configuration in which the downstream end of the second pipe K2d is connected to the suction side of an accumulator (not shown) is also included in the term "connected to the suction side of the compressor 1."

[0054] The on-off valve 14 shown in Fig. 7 is a solenoid valve for switching between flow and blocking of the refrigerant through the second pipe K2d and is provided in the second pipe K2d. The capillary tube 15 is a thin metal tube for reducing the pressure of the refrigerant flowing through the second pipe K2d. The capillary tube 15 is provided in the second pipe K2d downstream of the on-off valve 14. The temperature sensor 16 is a sensor for detecting the temperature of the refrigerant flowing from the receiver 5 through the second pipe K2d. The temperature sensor 16 is provided in the first pipe K1 downstream of the capillary tube 15. The temperature sensor 16 outputs the detected value from time to time to the control unit 13.

[0055] When the temperature sensor 16 detects a temperature below a predetermined value after the on-off valve 14 is opened during the refrigerant recovery operation, the control unit 13 stops the refrigerant recovery operation (i.e., stops the compressor 1). The "predetermined value" is a preset temperature threshold value that serves as a criterion for determining whether the refrigerant flowing through the second pipe K2d is in a liquid phase. Note that when the refrigerant flowing through the second pipe K2d changes from a gas phase to a liquid phase, the temperature sensor 16 detects a low value.

[0056] When the liquid level of the liquid refrigerant stored in the receiver 5 reaches the second pipe K2d (i.e., when the liquid refrigerant flows through the second pipe K2d), the refrigerant boils under reduced pressure and its temperature drops, causing the detection value of the temperature sensor 16 to fall below a predetermined value, and the control unit 13 stops the refrigerant recovery operation. This prevents a large amount of liquid refrigerant from accumulating in the receiver 5. When the refrigerant recovery operation is stopped, the control unit 13 closes the on-off valve 14. This allows the system to prepare for the next refrigeration cycle operation.

[0057] Incidentally, when the control unit 13 stops the refrigerant recovery operation, it is possible that the liquid level of the liquid refrigerant in the receiver 5 may slightly exceed the height position of the upstream end of the second pipe K2d, but this does not particularly pose a problem in suppressing the disproportionation reaction of the first refrigerant.

[0058] <Effects> According to the third embodiment, the control unit 13 opens the on-off valve 14 during the refrigerant recovery operation and stops the refrigerant recovery operation when the value detected by the temperature sensor 16 falls below a predetermined value. This makes it possible to keep the amount of liquid refrigerant stored in the receiver 5 below a volume determined by the height position of the upstream end of the second pipe K2d. This prevents the concentration of the gaseous first refrigerant from increasing in the system, and ultimately prevents the occurrence of a disproportionation reaction.

[0059] <<Modifications>> Although the refrigeration cycle apparatus 100 and the like according to the present disclosure have been described in the above embodiments, they are not limited to these descriptions and various modifications can be made. For example, in the first embodiment, the refrigeration cycle apparatus 100 (see FIG. 1 ) is described as having an expansion valve 7 (expansion mechanism), but this is not limiting. That is, an expansion mechanism such as a capillary tube may be provided instead of the expansion valve 7 (or together with the expansion valve 7). The same can be said for the second and third embodiments.

[0060] In the first embodiment, the refrigeration cycle apparatus 100 (see FIG. 1 ) is described as having the check valve 2 and the shutoff valve 6, but the present invention is not limited to this. For example, the check valve 2 and the shutoff valve 6 may be omitted as appropriate. In addition, in a configuration in which the shutoff valve 6 is omitted, the expansion valve 7 may be closed during the refrigerant recovery operation. The same applies to the second and third embodiments.

[0061] In addition, in each embodiment, the first refrigerant is any one of R1132(E), R1123, R1132(Z), and R1132a, but the present invention is not limited thereto. That is, any other predetermined refrigerant capable of causing a disproportionation reaction may be used as the first refrigerant.

[0062] In addition, in each embodiment, the second refrigerant is any one of R32, R1234yf, R1234ze(E), and R1234ze(Z), but this is not limiting. For example, one or more of R32, R1234yf, R1234ze(E), and R1234ze(Z) may be used as the second refrigerant. Furthermore, another specified refrigerant having a lower saturation pressure than the first refrigerant may be used as the second refrigerant.

[0063] In the first embodiment, the on-off valve 11 (see FIG. 1) is provided in the second pipe K2 (see FIG. 1), but this is not limiting. That is, the on-off valve 11 may be omitted as appropriate. The same applies to the second and third embodiments.

[0064] In the first embodiment, the downstream end (the other end) of the second pipe K2 is connected to the first pipe K1 (see FIG. 1 ) between the receiver 5 and the shutoff valve 6. However, this is not limiting. For example, the downstream end (the other end) of the second pipe K2 may be connected to another predetermined location in the first pipe K1. Even in this case, it is possible to prevent the amount of liquid refrigerant stored in the receiver 5 from becoming excessive, and thus to prevent the concentration of the gaseous first refrigerant from increasing inside the system.

[0065] Furthermore, for example, the control unit 13 may open the on-off valve 11 for a predetermined time while the compressor 1 is stopped (i.e., while the operation is stopped or while the thermostat is off). While the compressor 1 is stopped, the gas and liquid phase refrigerants in the system reach an equilibrium state, and the concentration of the gaseous first refrigerant tends to increase, but by performing the control described above, it is possible to suppress the increase in the concentration of the first refrigerant.

[0066] Furthermore, the respective embodiments and modifications can be combined as appropriate. For example, the second embodiment (see FIG. 6) may be combined with the first modification (see FIG. 4) so ​​that the pipe K2a is inserted into the bottom of the receiver 5. The second embodiment (see FIG. 6) may be combined with the second modification (see FIG. 5) so that the second pipe K2b is inserted into the top of the receiver 5. In addition, the third embodiment (see FIG. 7) may be combined with the first modification (see FIG. 4), or the third embodiment (see FIG. 7) may be combined with the second modification (see FIG. 5).

[0067] Furthermore, although each embodiment has been described with respect to a case where the receiver 5 is installed vertically, each embodiment can also be applied to a configuration where the receiver 5 is installed horizontally or obliquely. Furthermore, each embodiment has been described with respect to a case where the refrigeration cycle apparatus 100 is not particularly provided with a four-way valve, but this is not limited thereto. For example, when the refrigeration cycle apparatus 100 is used as an air conditioner, a four-way valve (not shown) for switching the refrigerant flow path between the cooling cycle and the heating cycle may be provided. Additionally, well-known components such as a supercooler may be added as appropriate.

[0068] Furthermore, each embodiment has been described in detail to clearly explain the present disclosure, and is not necessarily limited to having all of the described configurations. Furthermore, it is possible to appropriately add, delete, or replace part of the configuration of each embodiment with other configurations. Furthermore, the above-described mechanisms and configurations are those considered necessary for explanation, and do not necessarily represent all mechanisms and configurations of the product.

[0069] REFRIGERATION CYCLE DEVICE K1 FIRST PIPE K2, K2a, K2b, K2c, K2d SECOND PIPE Q1 REFRIGERATOR CIRCUIT ...2, K2a, K2b, K2c, K2d SECOND PIPE Q2, K2a, K2b, K2c, K2d SECOND PIPE Q3, K4, K5, K6, K7, K8, K9, K10, K11, K12, K13, K14, K15, K16, K17, K18, K19, K20, K210, K221, K230, K241, K252

Claims

1. A refrigeration cycle device comprising a refrigerant circuit in which a compressor, a heat source side heat exchanger, a receiver, an expansion mechanism, and a load side heat exchanger are connected in sequence in a ring, wherein the refrigerant sealed in the refrigerant circuit is a non-azeotropic refrigerant mixture containing a first refrigerant in which a disproportionation reaction can occur and a second refrigerant having a lower saturation pressure than the first refrigerant, and further comprising: a first pipe that guides the refrigerant from the receiver to the compressor via the expansion mechanism and the load side heat exchanger in sequence, and a second pipe having one end connected to the receiver and the other end connected to the first pipe.

2. The refrigeration cycle device according to claim 1, wherein the first refrigerant is R1132(E) or R1123, and the second refrigerant is R1234yf.

3. A refrigeration cycle device as described in claim 1, comprising: a discharge pressure sensor that detects the discharge pressure of the compressor; a shut-off valve provided in the first pipe between the receiver and the expansion mechanism; an on-off valve provided in the second pipe; and a control unit that controls the shut-off valve and the on-off valve, wherein the other end of the second pipe is connected in the first pipe between the receiver and the shut-off valve, and the control unit opens the on-off valve while maintaining the shut-off valve in a closed state during refrigerant recovery operation, and stops the refrigerant recovery operation when the detection value of the discharge pressure sensor reaches a predetermined value.

4. A refrigeration cycle device as described in claim 1, comprising: a shut-off valve provided in the first pipe between the receiver and the expansion mechanism; an on-off valve provided in the second pipe; and a control unit that controls the shut-off valve and the on-off valve, wherein the other end of the second pipe is connected in the first pipe between the shut-off valve and the expansion mechanism, and the control unit opens the on-off valve while maintaining the shut-off valve in a closed state during refrigerant recovery operation.

5. A refrigeration cycle device according to claim 1, comprising: an on-off valve provided in the second piping; a capillary tube for reducing the pressure of the refrigerant flowing through the second piping; a temperature sensor for detecting the temperature of the refrigerant flowing through the second piping; and a control unit for controlling the on-off valve, wherein the other end of the second piping is connected to the suction side of the compressor in the first piping, and wherein the control unit opens the on-off valve during execution of a refrigerant recovery operation and then stops the refrigerant recovery operation when the detected value of the temperature sensor falls below a predetermined value.

Images