Refrigeration cycle device

Abstract

The present invention makes it possible to suppress discharge and combustion of a flammable first refrigerant in an undesirable location when the pressure of the first refrigerant in a first circuit has become high due to an external factor or the like in a refrigeration cycle device that employs a highly flammable refrigerant. A refrigeration cycle device (1) comprises a first circuit (100) and a second circuit (200). The first circuit (100) circulates a first medium, which is a highly flammable refrigerant. The second circuit (200) circulates a second medium, which exchanges heat with the first medium. The first circuit (100) has a first heat exchanger, which exchanges heat with air. Among components that form the first circuit (100), a first heat exchanger (120) has a lower pressure capacity than the others.

Description

Refrigeration cycle equipment

[0001] This relates to a refrigeration cycle device.

[0002] From the perspective of preventing global warming, a shift to refrigerants with low global warming potential (GWP) is progressing on a global scale. Patent Document 1 (International Publication No. 2020-202560) introduces a refrigeration cycle device that uses R290 (propane) as a refrigerant. R290 is one of the refrigerants with a low GWP.

[0003] R290 has a higher flammability than hydrofluorocarbons. For example, in the international standard ISO 817, which defines the safety grades of refrigerants, R32 (difluoromethane), a type of hydrofluorocarbon, is registered as slightly flammable (Class 2L), while R290 is registered as highly flammable (Class 3). Therefore, in a refrigeration cycle device using a highly flammable refrigerant, it is desirable to suppress the release and combustion of the first refrigerant in undesirable locations when the pressure of the flammable first refrigerant in the first circuit increases due to external factors or the like.

[0004] A refrigeration cycle device according to a first aspect includes a first circuit and a second circuit. A first medium, which is a highly flammable refrigerant, circulates through the first circuit. A second medium, which exchanges heat with the first medium, circulates through the second circuit. The first circuit includes a first heat exchanger that exchanges heat with air. Of the components constituting the first circuit, the first heat exchanger has a lower pressure resistance than the other components.

[0005] Here, the refrigeration cycle device can suppress the release and combustion of the first refrigerant in undesirable locations when the pressure of the flammable first refrigerant in the first circuit becomes high due to external factors or the like.

[0006] A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the first heat exchanger has flat tubes 93. The pressure resistance strength of the flat tubes 93 is smaller than the pressure resistance strength of the other components.

[0007] A refrigeration cycle device according to a third aspect is the refrigeration cycle device according to the second aspect, wherein the thin-walled portion of the flat tubes 93 has a thickness of 0.1 to 0.9 mm.

[0008] A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to the second or third aspect, wherein the flat tubes 93 are made of aluminum or an aluminum alloy.

[0009] A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the fourth aspect, wherein the first heat exchanger has a header, and the pressure resistance strength of the header is lower than the pressure resistance strength of the other components.

[0010] A refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to any one of the first to fifth aspects, wherein the first circuit includes a second heat exchanger that exchanges heat between the first medium and the second medium, and a pipe connecting the first heat exchanger and the second heat exchanger is a copper pipe.

[0011] A refrigeration cycle apparatus according to a seventh aspect is the refrigeration cycle apparatus according to any one of the first aspect to the sixth aspect, wherein a main surface of the first heat exchanger that occupies 50% or more of the first heat exchanger faces a wall surface of a building.

[0012] A refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to any one of the first to seventh aspects, wherein a main surface occupying 50% or more of the first heat exchanger faces the fan.

[0013] A ninth aspect of the present invention is the refrigeration cycle apparatus of any one of the first to eighth aspects, wherein the highly flammable refrigerant is R290.

[0014] Fig. 1 is a schematic configuration diagram of a refrigeration cycle device according to one embodiment. Fig. 2 is a schematic perspective view of an outdoor unit of a refrigeration cycle device including a first heat exchanger. Fig. 3 is a schematic view of an outdoor unit of a refrigeration cycle device including a first heat exchanger. Fig. 4 is a schematic perspective view of the first heat exchanger. Fig. 5 is a partial enlarged view of a heat exchange section of the first heat exchanger cut in the vertical direction. Fig. 6 is a block diagram of a control unit.

[0015] Hereinafter, a refrigeration cycle device 1 according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the following embodiment is a specific example and does not limit the technical scope, and can be appropriately modified without departing from the gist of the present disclosure.

[0016] In the following description, expressions indicating directions such as "up," "down," "front," "rear," "left," and "right" are used as appropriate, and these indicate the directions in a state in which the refrigeration cycle apparatus 1 is installed and in normal use. In this embodiment, the up and down direction is the vertical direction.

[0017] 1 is a schematic diagram of a refrigeration cycle apparatus 1 according to one embodiment. The refrigeration cycle apparatus 1 includes a first circuit 100, an outdoor unit 400 (shown in FIG. 2), a second circuit 200, and a control unit 300 (shown in FIG. 6).

[0018] The refrigeration cycle apparatus 1 performs cooling and heating operations. More specifically, the refrigeration cycle apparatus 1 causes the refrigerant filled in the first circuit 100 to perform a refrigeration cycle, and heats or cools the water filled in the second circuit 200, thereby performing heating and cooling operations using the water in a space to be air-conditioned (not shown).

[0019] (2) Detailed Configuration (2-1) First Circuit 100 The first circuit 100 includes a compressor 110, a first heat exchanger 120, a second heat exchanger 130, a switching mechanism 140, and an expansion mechanism 150. The components of the first circuit 100 are connected by piping. A first medium, which is a highly flammable refrigerant, circulates through the first circuit 100. The first medium is a refrigerant that has high flammability and is classified as highly flammable (Class 3) in the international standard ISO 817. In this embodiment, the first medium is R290 (propane).

[0020] (2-1-1) Compressor 110 The compressor 110 compresses low-pressure refrigerant in the refrigeration cycle to high pressure using a compression mechanism (not shown). The compressor 110 has a suction section 110a and a discharge section 110b.

[0021] The suction section 110a draws low-pressure refrigerant from the first circuit 100 and supplies it to the compression mechanism. The discharge section 110b discharges the refrigerant compressed to high pressure by the compression mechanism to the first circuit 100. The compression capacity of the compressor 110 is controlled by the control section 300.

[0022] (2-1-2) First Heat Exchanger 120 The first heat exchanger 120 exchanges heat between the refrigerant filled in the first circuit 100 and the air in the location where the first heat exchanger 120 is installed. The first heat exchanger 120 is installed outside the space to be air-conditioned, such as outdoors. Although not limited thereto, the first heat exchanger 120 is a microchannel type heat exchanger.

[0023] The first heat exchanger 120 is made entirely of aluminum or an aluminum alloy. Therefore, the pressure resistance of the first heat exchanger 120 is lower than the pressure resistance of the other components. These other components are the compressor 110, the second heat exchanger 130, the switching mechanism 140, the expansion mechanism 150, the piping connecting these components to each other, and the piping connecting these components to the first heat exchanger 120. The other components are made of, for example, copper.

[0024] As shown in Figures 2 to 4, the first heat exchanger 120 extends leftward from near the end of the partition plate 415 along the rear side of the casing 41 of the outdoor unit 400 (described later), changes direction near the left rear corner of the casing 41, and extends forward along the left side plate 414.

[0025] The first heat exchanger 120 has a main surface A that occupies 50% or more of the first heat exchanger 120 and a surface B that occupies less than 50% of the first heat exchanger 120. The main surface A faces a wall surface of a building (not shown). The main surface A also faces the fan 42 of the outdoor unit 400 of the refrigeration cycle apparatus 1.

[0026] The first heat exchanger 120 has a first end 120a, a second end 120b, flat tubes 93, a heat exchange section 95, and headers 91 and 92. The heat exchange section 95 has a plurality of flat tubes 93 and a plurality of insert fins 94.

[0027] The first end 120a and the second end 120b function as an inlet and an outlet for the refrigerant to and from the first heat exchanger 120. The heat exchange section 95 has a plurality of flat tubes 93 and a plurality of insert fins 94.

[0028] The flat tubes 93 allow a refrigerant to flow therethrough. Figure 5 is a partial enlarged view of the heat exchanger 95 when the flat tubes 93 and the insert fins 94 are cut vertically. The flat tubes 93 function as heat transfer tubes, transferring heat transferred between the insert fins 94 and the outdoor air to the refrigerant flowing therethrough. The flat tubes 93 are formed with a plurality of through-holes aligned in a predetermined direction, through which the refrigerant passes to be heat exchanged with the outdoor air in the first heat exchanger 120. The through-holes of the flat tubes 93 extend in the direction in which the first heat exchanger 120 extends.

[0029] The flat tubes 93 are also made of aluminum or an aluminum alloy, and therefore the pressure resistance of the flat tubes 93 is smaller than the pressure resistance of the other components described above.

[0030] The flat tubes 93 have side surfaces 93b that serve as heat transfer surfaces and a plurality of internal flow paths 93a through which the refrigerant flows. The flat tubes 93 are arranged in a plurality of stages at intervals with the side surfaces 93b of adjacent flat tubes 93 facing each other vertically.

[0031] The side wall portion 93b of the flat tube 93 is a thin wall portion having a thickness of 0.1 to 0.9 mm.

[0032] The insertion fins 94 are a plurality of fins and are flat plate-shaped members. The insertion fins 94 are connected to the flat tubes 93. The insertion fins 94 have a plurality of horizontally elongated notches 94a formed therein so that the insertion fins 94 can be inserted into the multiple rows of flat tubes 93 arranged between the headers 91, 92. The shape of the notches 94a of the insertion fins 94 roughly matches the outer shape of the cross section of the flat tubes 93.

[0033] The multiple insertion fins 94 are stacked in a first direction in which the flat tubes 93 extend. The multiple insertion fins 94 also extend in the vertical direction so as to intersect with the flat tubes 93 (here, perpendicularly).

[0034] The insert fins 94 increase the heat transfer area between the flat tubes 93 and the outside air, thereby promoting heat exchange between the refrigerant and the outside air.

[0035] The headers 91, 92 are arranged one on each end of the heat exchange section 95. A plurality of flat tubes 93 are connected to the headers 91, 92. The headers 91, 92 are also made of aluminum or an aluminum alloy. Therefore, the pressure resistance strength of the headers 91, 92 is smaller than the pressure resistance strength of the other components described above.

[0036] The headers 91, 92 collect the refrigerant passing through the inside of the plurality of flat tubes 93. A partition plate may be formed inside the headers 91, 92 to separate the internal space.

[0037] (2-1-3) Second Heat Exchanger 130 The second heat exchanger 130 exchanges heat between the refrigerant filling the first circuit 100 and the water filling the second circuit 200. The second heat exchanger 130 has a refrigerant flow path 131 and a water flow path 132.

[0038] The refrigerant flowing through the first circuit 100 passes through the refrigerant flow path 131. The refrigerant flow path 131 has a first end 131a and a second end 131b. The first end 131a functions as an inlet for the refrigerant flowing out of the refrigerant flow path 131. The second end 131b functions as an outlet for the refrigerant flowing in from the refrigerant flow path 131.

[0039] The water flow path 132 is passed through by the water flowing through the second circuit 200. The water flow path 132 has a first end 132a and a second end 132b. The first end 132a functions as an outlet for water flowing out of the water flow path 132. The second end 132b functions as an outlet for water flowing into the water flow path 132.

[0040] The second heat exchanger 130 may be, but is not limited to, a plate-type heat exchanger.

[0041] The second heat exchanger 130 is made entirely of a non-aluminum material or a non-aluminum alloy, for example, copper.

[0042] The piping connecting the second heat exchanger 130 and the first heat exchanger 120 is all made of non-aluminum or a non-aluminum alloy. The piping connecting the second heat exchanger 130 and the first heat exchanger 120 is, for example, copper piping. Note that the piping connecting the second heat exchanger 130 and the first heat exchanger 120 refers to the piping arranged between the second heat exchanger 130 and the first heat exchanger 120.

[0043] (2-1-4) Switching Mechanism 140 As shown in Fig. 1, the switching mechanism 140 switches the direction of refrigerant flow in the first circuit 100 between two states. The switching mechanism 140 is a four-way switching valve. The switching mechanism 140 has a first port P1, a second port P2, a third port P3, and a fourth port P4.

[0044] The first port P1 is connected to the discharge portion 110b of the compressor 110. The second port P2 is connected to the second end 120b of the first heat exchanger 120. The third port P3 is connected to the suction portion 110a of the compressor 110. The fourth port P4 is connected to the second end 131b of the refrigerant flow path 131 of the second heat exchanger 130.

[0045] The switching mechanism 140 switches between a first state (a state indicated by a solid line in FIG. 1 ) and a second state (a state indicated by a dashed line in FIG. 1 ). In the first state, the switching mechanism 140 connects the first port P1 to the second port P2 and connects the third port P3 to the fourth port P4. In the second state, the switching mechanism 140 connects the first port P1 to the fourth port P4 and connects the second port P2 to the third port P3. The state of the switching mechanism 140 is controlled between the first state and the second state by the control unit 300.

[0046] (2-1-5) Expansion Mechanism 150 The expansion mechanism 150 reduces the pressure of the refrigerant flowing between the first end 120a of the first heat exchanger 120 and the first end 131a of the refrigerant flow path 131 of the second heat exchanger 130. One end of the expansion mechanism 150 is connected to the first end 120a of the first heat exchanger 120, and the other end is connected to the first end 131a of the refrigerant flow path 131 of the second heat exchanger 130.

[0047] Although not limited to this, the expansion mechanism 150 is an electric expansion valve. The opening degree of the expansion mechanism 150 is controlled by the control unit 300.

[0048] (2-2) Outdoor Unit 400 The outdoor unit 400 includes a fan 42 and a casing 41 .

[0049] (2-2-1) Fan 42 The fan 42 causes outside air to flow through the first heat exchanger 120. The fan 42 is driven by a fan motor.

[0050] (2-2-2) Casing 41 The casing 41 shown in FIGS. 2 and 3 houses the first heat exchanger 120 and the fan 42 .

[0051] The casing 41 has a substantially rectangular parallelepiped shape and includes a front panel 411 , a top panel 412 , a bottom panel 413 , and side panels 414 .

[0052] The front plate 411 is a plate-like member that forms the front surface of the casing 41. An air outlet (not shown) is formed in the front plate 411. The air outlet is an opening for blowing outside air taken in from the outside of the casing 41 to the inside of the casing 41 out of the casing 41.

[0053] The top plate 412 is a plate-like member disposed on the upper side of the casing 41. The bottom plate 413 is a plate-like member that forms the lower surface of the casing 41. The top plate 412 and the bottom plate 413 face each other.

[0054] The side plates 414 are plate-like members that form the side surfaces of the casing 41. The side plates have a left side plate and a right side plate. The lower portions of the side plates 414 are fixed to the bottom plate 413.

[0055] The casing 41 further includes a partition plate 415. The partition plate 415 is a plate-shaped member that extends in the vertical direction. A lower portion of the partition plate 415 is fixed to the bottom plate 413 of the casing 41.

[0056] The partition plate 415 divides the inside of the casing 41 into a fan chamber S1 and a machine chamber S2. The fan chamber S1 and the machine chamber S2 are each a space defined by the front plate 411, the top plate 412, the bottom plate 413, and the side plates 414 of the casing 41 and the partition plate 415.

[0057] (2-3) Second Circuit 200 As shown in FIG. 1, the second circuit 200 includes a pump 210 and a third heat exchanger 220. The second circuit 200 is filled with a second medium, which is a heat transfer medium. The second medium exchanges heat with the first medium. In this embodiment, the second medium is water. Each section of the second circuit 200 is connected by piping.

[0058] (2-3-1) Pump 210 The pump 210 circulates the water filled in the second circuit 200 through the second circuit 200. The pump 210 has a suction portion 210a and a discharge portion 210b.

[0059] The pump 210 applies a predetermined pressure to the water sucked into the second circuit 200 through the suction port 210a, and discharges the water from the discharge port 210b back into the second circuit 200.

[0060] The suction portion 210a is connected to a second end 220b (described later) of the third heat exchanger 220. The discharge portion 210b is connected to a second end 132b of the water flow path 132 of the second heat exchanger 130. The pump 210 is controlled by the control portion 300.

[0061] (2-3-2) Third Heat Exchanger 220 The third heat exchanger 220 exchanges heat between the water filled in the second circuit 200 and the air in the location where the third heat exchanger 220 is installed. The third heat exchanger 220 has a first end 220a and a second end 220b. The first end 220a functions as an inlet for water flowing into the third heat exchanger 220. The second end 220b functions as an outlet for water flowing out of the third heat exchanger 220. The first end 220a is connected to the first end 132a of the water flow path 132 of the second heat exchanger 130.

[0062] The third heat exchanger 220 is installed in the space to be air-conditioned.

[0063] (2-4) Control Unit 300 Fig. 6 is a block diagram of the control unit 300. The control unit 300 controls each device in the first circuit 100 to cause the first circuit 100 to perform a refrigeration cycle and realize cooling operation and heating operation in the space to be air-conditioned. The control unit 300 is electrically connected to the compressor 110, the switching mechanism 140, the expansion mechanism 150, and the pump 210 so as to be able to send and receive signals to and from them.

[0064] The control unit 300 is realized by a computer. The control unit 300 includes a control and arithmetic unit and a storage device (both not shown). The control and arithmetic unit can be a processor such as a CPU or a GPU. The control and arithmetic unit reads a program stored in the storage device and performs predetermined arithmetic processing in accordance with the program. Furthermore, the control and arithmetic unit can write the results of calculations to the storage device and read information stored in the storage device in accordance with the program.

[0065] (3) Overall Operation The control unit 300 controls each device during cooling operation and heating operation as described below.

[0066] (3-1) Cooling operation When the refrigeration cycle device 1 is instructed to perform cooling operation, the control unit 300 causes the compressor 110 and the pump 210 to start operating, sets the switching mechanism 20 to the first state, and controls the opening degree of the expansion mechanism 150.

[0067] (3-1-1) First Circuit 100 When the compressor 110 starts operating, low-pressure gas refrigerant in the refrigeration cycle is drawn in through the suction port 110a, compressed to the high-pressure state in the refrigeration cycle, and then discharged as gas refrigerant from the discharge port 110b.

[0068] The high-pressure gas refrigerant flowing out from the discharge port 110b passes through the switching mechanism 140, in this order, via the first port P1 and the second port P2, and flows into the first heat exchanger 120 from the second end 120b. The refrigerant that flows into the first heat exchanger 120 exchanges heat with the air in the location where the first heat exchanger 120 is installed, condensing and becoming a high-pressure liquid refrigerant, which flows out from the first end 120a. In other words, the first heat exchanger 120 functions as a radiator.

[0069] The high-pressure refrigerant flowing out of the first heat exchanger 120 passes through the expansion mechanism 150 and flows from the first end 131a into the refrigerant flow path 131 of the second heat exchanger 130. The refrigerant that has passed through the expansion mechanism 150 is decompressed to a low pressure and becomes a gas-liquid two-phase refrigerant.

[0070] The refrigerant that has flowed into the refrigerant flow path 131 exchanges heat with the water flowing through the water flow path 132 and evaporates, becoming a low-pressure gas refrigerant that flows out from the second end 131b. In other words, the refrigerant flow path 131 of the second heat exchanger 130 functions as an evaporator.

[0071] The low-pressure refrigerant flowing out of the second heat exchanger 130 passes through the switching mechanism 140 via the fourth port P4 and the third port P3 in this order, and is again drawn into the compressor 110 via the suction section 110a.

[0072] (3-1-2) Second Circuit 200 When the pump 210 starts operating, the refrigerant filled in the second circuit 200 is drawn in through the suction port 210a and then discharged from the discharge port 210b.

[0073] The water flowing out from the discharge port 210b flows into the water flow path 132 of the second heat exchanger 130 from the second end 132b. The water that has flowed into the water flow path 132 exchanges heat with the refrigerant flowing through the refrigerant flow path 131 (is cooled), and then flows out from the first end 132a.

[0074] The water flowing out of the second heat exchanger 130 flows into the third heat exchanger 220 from the first end 220a. The water flowing into the third heat exchanger 220 exchanges heat with the air in the location where the third heat exchanger 220 is installed. This cools the air in the space to be air-conditioned.

[0075] The water that has exchanged heat with the air in the location where the third heat exchanger 220 is installed flows out from the second end 220b and is then sucked into the pump 210 again from the suction port 210a.

[0076] (3-2) Heating Operation When the refrigeration cycle device 1 is instructed to perform heating operation, the control unit 300 causes the compressor 110 and the pump 210 to start operating, sets the switching mechanism 20 to the second state, and controls the opening degree of the expansion mechanism 150.

[0077] (3-2-1) First Circuit 100 When the compressor 110 starts operating, low-pressure gas refrigerant in the refrigeration cycle is drawn in through the suction port 110a, compressed to the high-pressure state in the refrigeration cycle, and then discharged as gas refrigerant from the discharge port 110b.

[0078] The high-pressure gas refrigerant flowing out from the discharge port 110b passes through the switching mechanism 140, in this order, via the first port P1 and the fourth port P4, and flows into the refrigerant flow path 131 of the second heat exchanger 130 from the second end 131b. The refrigerant that has flowed into the second heat exchanger 130 exchanges heat with water flowing through the water flow path 132, condenses, and becomes high-pressure liquid refrigerant, which flows out from the first end 131a. In other words, the refrigerant flow path 131 of the second heat exchanger 130 functions as a radiator.

[0079] The high-pressure refrigerant flowing out of the second heat exchanger 130 passes through the expansion mechanism 150 and flows into the first heat exchanger 120 from the first end 120a. The refrigerant that has passed through the expansion mechanism 150 is decompressed to a low pressure and becomes a gas-liquid two-phase refrigerant.

[0080] The refrigerant that flows into the first heat exchanger 120 exchanges heat with the air in the location where the first heat exchanger 120 is installed, evaporating, and becomes a low-pressure gas refrigerant that flows out from the second end 120b. In other words, the first heat exchanger 120 functions as an evaporator.

[0081] The low-pressure refrigerant that has flowed out into the first heat exchanger 120 passes through the switching mechanism 140, in this order, via the second port P2 and the third port P3, and is again drawn into the compressor 110 through the suction section 110a.

[0082] (3-2-2) Second Circuit 200 When the pump 210 starts operating, the refrigerant filled in the second circuit 200 is drawn in through the suction port 210a and then discharged from the discharge port 210b.

[0083] The water flowing out from the discharge port 210b flows into the water flow path 132 of the second heat exchanger 130 from the second end 132b. The water that flows into the water flow path 132 exchanges heat with the refrigerant flowing through the refrigerant flow path 131 (is heated), and then flows out from the first end 132a.

[0084] The water flowing out of the second heat exchanger 130 flows into the third heat exchanger 220 from the first end 220a. The water flowing into the third heat exchanger 220 exchanges heat with the air in the location where the third heat exchanger 220 is installed. This heats the air in the space to be air-conditioned.

[0085] The water that has exchanged heat with the air in the location where the third heat exchanger 220 is installed flows out from the second end 220b and is then sucked into the pump 210 again from the suction port 210a.

[0086] (4) Features (4-1) The refrigeration cycle device 1 of this embodiment includes a first circuit 100 and a second circuit 200. A first medium, which is a highly flammable refrigerant, circulates through the first circuit 100. A second medium, which exchanges heat with the first medium, circulates through the second circuit 200. The first circuit 100 includes a first heat exchanger 120 that exchanges heat with air. Of the components constituting the first circuit 100, the first heat exchanger 120 has a lower pressure resistance than the other components.

[0087] In the refrigeration cycle apparatus 1, the pressure of the flammable first refrigerant in the first circuit may sometimes increase due to an external factor (hereinafter referred to as an abnormal pressure state). An example of such an external factor is a fire. In such a case, it is undesirable for the first medium, which is a highly flammable refrigerant, to be released in any location. In this embodiment, the pressure resistance of the first heat exchanger 120 is lower than that of the other components. Therefore, in the event of an abnormal pressure state, the first heat exchanger 120 is the first to burst in the refrigeration cycle apparatus 1. Because the first heat exchanger 120 is located outdoors, it can release the first refrigerant into the air (atmosphere). As a result, the release and combustion of the first refrigerant in undesirable locations can be suppressed.

[0088] (4-2) Here, the first heat exchanger 120 has flat tubes 93. The pressure resistance of the flat tubes 93 is lower than the pressure resistance of the other components. In the event of an abnormal pressure state, the flat tubes 93 will burst first in the refrigeration cycle apparatus 1. As a result, it is possible to suppress the release and combustion of the first refrigerant in undesirable locations.

[0089] (4-3) Here, the thickness of the thin-walled portion of the flat tube 93 is 0.1 to 0.9 mm. The flat tube 93 maintains the necessary strength when there is no abnormal pressure, but becomes prone to bursting when there is an abnormal pressure.

[0090] (4-4) Here, the flat tubes 93 are made of aluminum or an aluminum alloy. The flat tubes 93 are made of a material that is weaker than the other components, and therefore are more likely to burst under abnormal pressure.

[0091] (4-5) Here, the first circuit 100 further includes a second heat exchanger 130 that exchanges heat between the first medium and the second medium. The piping connecting the first heat exchanger 120 and the second heat exchanger 130 is a copper pipe.

[0092] In an abnormal pressure state, the first heat exchanger 120 ruptures before the piping connecting the first heat exchanger 120 and the second heat exchanger 130 ruptures, thereby preventing the first refrigerant from being released and combusted in undesirable locations.

[0093] (4-6) Here, the main surface of the first heat exchanger 120, which occupies 50% or more of the first heat exchanger 120, faces the wall surface of the building.

[0094] Even if the first heat exchanger 120 bursts in an abnormal pressure state and the leaked first medium catches fire, the walls of the building can prevent the fire from spreading to the surrounding area.

[0095] (4-7) Here, the main surface of the first heat exchanger 120, which occupies 50% or more of the surface, faces the fan 42. In an abnormal pressure state, the first medium leaking due to the rupture of the first heat exchanger 120 can be unidirectionally circulated by the fan 42. This makes it possible to prevent the spread of fire.

[0096] (4-8) Here, the highly flammable refrigerant is R290.

[0097] (5) Modifications (5-1) Modification A In the above embodiment, the pressure resistance strength of the flat tubes 93 is set to be smaller than the pressure resistance strength of the other components, but this is not particularly limited. For example, the pressure resistance strength of the header may be set to be smaller than the pressure resistance strength of the other components. In this case, the header will rupture first in an abnormal pressure state. As a result, it is possible to suppress the release and combustion of the first refrigerant in undesirable locations.

[0098] (5-2) Modification B In the above embodiment, R290 is used as the first medium, but this is not a limitation. The first medium may also be a hydrocarbon having one to four carbon atoms, such as R1270 (propylene), R600 (butane), or R600a (isobutane).

[0099] (5-3) Modification C In the above embodiment, in the second heat exchanger 130, the refrigerant flowing through the first circuit 100 exchanges heat with the water flowing through the second circuit 200. However, this is not limited to this. As shown in Fig. 7 , in this modification, the refrigerant flowing through the first circuit 100 may exchange heat with the air in the target space. In this case, the second circuit 200 and the second heat exchanger 130 are omitted, and the third heat exchanger 220 is disposed in the target space.

[0100] In this modification, the third heat exchanger 220 is entirely made of non-aluminum or a non-aluminum alloy. The third heat exchanger 220 is made of, for example, copper. The third heat exchanger 220 is placed in the space to be air-conditioned. If the third heat exchanger 220 is made of non-aluminum, it has a higher pressure resistance than the first heat exchanger 120, which is made of aluminum. Therefore, it is possible to reduce the possibility of the third heat exchanger 220 placed in the space to be air-conditioned bursting in an abnormal pressure state.

[0101] In this modification, all of the piping connecting the first heat exchanger 120 and the third heat exchanger 220 is made of non-aluminum or a non-aluminum alloy. The piping connecting the first heat exchanger 120 and the third heat exchanger 220 is, for example, copper piping. Note that the piping connecting the first heat exchanger 120 and the third heat exchanger 220 refers to the piping disposed between the first heat exchanger 120 and the third heat exchanger 220.

[0102] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0103] REFRIGERATION CYCLE DEVICE 42 FAN 91, 92 Header 93 Flat tube 93b Thin-walled portion of flat tube 100 First circuit 110 Compressor 120 First heat exchanger 130 Second heat exchanger 140 Switching mechanism 200 Second circuit 210 Pump 220 Third heat exchanger 300 Control unit A Main surface of first heat exchanger

[0104] International Publication No. 2020-202560

Claims

1. A refrigeration cycle device (1), comprising: a first circuit (100) through which a first medium, which is a highly flammable refrigerant, circulates; and a second circuit (200) through which a second medium circulates and exchanges heat with the first medium, wherein the first circuit has a first heat exchanger (120) that exchanges heat with air, and among the components constituting the first circuit, the pressure resistance strength of the first heat exchanger is lower than the pressure resistance strength of the other components.

2. The refrigeration cycle apparatus according to claim 1, wherein the first heat exchanger has flat tubes (93), and the pressure resistance of the flat tubes is lower than the pressure resistance of other components.

3. The refrigeration cycle device according to claim 2, wherein the thickness of the thin-walled portion (93b) of the flat tube is 0.1 to 0.9 mm.

4. The refrigeration cycle device according to claim 2 or 3, wherein the flat tubes are made of aluminum or an aluminum alloy.

5. A refrigeration cycle device according to any one of claims 1 to 4, wherein the first heat exchanger has a header (91, 92), and the pressure resistance of the header is lower than the pressure resistance of other components.

6. A refrigeration cycle device according to any one of claims 1 to 5, wherein the first circuit has a second heat exchanger (130) that exchanges heat between the first medium and the second medium, and piping connecting the first heat exchanger and the second heat exchanger is a copper pipe.

7. A refrigeration cycle device according to any one of claims 1 to 6, wherein a main surface (A) that occupies 50% or more of the first heat exchanger faces a wall surface of a building.

8. A refrigeration cycle device according to any one of claims 1 to 7, wherein a main surface of the first heat exchanger, which occupies 50% or more of the main surface, faces a fan.

9. The refrigeration cycle device according to any one of claims 1 to 8, wherein the highly flammable refrigerant is R290.

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