Refrigeration cycle device

Abstract

In relation to refrigeration cycle devices that employ highly flammable refrigerants, the present invention makes it possible to suppress discharge and combustion of a flammable refrigerant in an undesirable location when the pressure of the refrigerant in a refrigerant circuit has become high due to an external factor or the like. A refrigeration cycle device (1) comprises a refrigerant circuit (100) and a protection unit (500). A highly flammable refrigerant circulates through the refrigerant circuit (100). The protection unit (500) is disposed in the refrigerant circuit (100). The protection unit (500) discharges the refrigerant to the outside of the refrigerant circuit either before the refrigerant pressure reaches a pressure corresponding to the spontaneous ignition temperature of the refrigerant or before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant.

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 ISO817, 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 R290, when the pressure of a flammable refrigerant in the refrigerant circuit becomes high due to an external factor or the like, it is desirable to suppress the release and combustion of the refrigerant in undesirable locations.

[0004] A refrigeration cycle apparatus according to a first aspect includes a refrigerant circuit and a protection unit. A highly flammable refrigerant circulates through the refrigerant circuit. The protection unit is disposed within the refrigerant circuit. The protection unit releases the refrigerant from the refrigerant circuit before the refrigerant pressure reaches a pressure corresponding to the spontaneous ignition temperature of the refrigerant or before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant.

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

[0006] A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the refrigerant circuit includes a heat exchanger that exchanges heat with air, and the protection unit is disposed near the heat exchanger or at the heat exchanger.

[0007] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, further comprising an outdoor unit. The outdoor unit has a machine chamber and a blower chamber. The protection section is disposed in the blower chamber.

[0008] A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to the second aspect, wherein the protection portion is disposed above the center of the height dimension of the heat exchanger.

[0009] A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to the second aspect, wherein the protection portion is disposed below the center of the height dimension of the heat exchanger.

[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 protection part is a safety valve having a rupture disc.

[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 the protective portion is a fusible plug.

[0012] A refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the seventh aspect, wherein the highly flammable refrigerant is R290.

[0013] A refrigeration cycle device of a ninth aspect is the refrigeration cycle device of any one of the first aspect to the eighth aspect, wherein "before the refrigerant pressure reaches a pressure equivalent to the spontaneous ignition temperature of the refrigerant" refers to when the refrigerant pressure reaches a pressure equivalent to a temperature of the spontaneous ignition temperature of the refrigerant × (0.5 to 0.9).

[0014] A refrigeration cycle device of a tenth aspect is the refrigeration cycle device of any one of the first aspect to the ninth aspect, wherein "before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant" means when the refrigerant temperature reaches a temperature of the spontaneous ignition temperature of the refrigerant × (0.5 to 0.9).

[0015] Fig. 1 is a schematic configuration diagram of a refrigeration cycle apparatus according to one embodiment. Fig. 2 is a schematic perspective view of an outdoor unit of a refrigeration cycle apparatus including a first heat exchanger. Fig. 3 is a schematic view of an outdoor unit of a refrigeration cycle apparatus including a first heat exchanger. Fig. 4 is a schematic perspective view of the first heat exchanger. Fig. 5 is a block diagram of a control unit. Fig. 6 is a schematic view of an outdoor unit of a refrigeration cycle apparatus including a first heat exchanger in a modified example.

[0016] 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.

[0017] 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.

[0018] 1 is a schematic diagram of a refrigeration cycle apparatus 1 according to one embodiment. The refrigeration cycle apparatus 1 includes a refrigerant circuit 100, an outdoor unit 400 (shown in FIG. 2), a protection unit 500, a water circuit 200, and a control unit 300 (shown in FIG. 5).

[0019] The refrigeration cycle apparatus 1 performs cooling operation and heating operation. More specifically, the refrigeration cycle apparatus 1 causes the refrigerant filled in the refrigerant circuit 100 to perform a refrigeration cycle, and heats or cools the water filled in the water circuit 200, thereby performing heating operation and cooling operation using the water in a space to be air-conditioned (not shown).

[0020] (2) Detailed Configuration (2-1) Refrigerant Circuit 100 The refrigerant circuit 100 includes a compressor 110, a first heat exchanger 120, a third heat exchanger 130, a switching mechanism 140, and an expansion mechanism 150. The components of the refrigerant circuit 100 are connected by pipes. A highly flammable refrigerant circulates through the refrigerant circuit 100. The refrigerant is a highly flammable refrigerant classified as highly flammable (Class 3) in the international standard ISO 817. Examples of highly flammable refrigerants include hydrocarbons such as R600 (butane) and R600a (isobutane). In this embodiment, the refrigerant is R290 (propane).

[0021] (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.

[0022] The suction section 110a draws low-pressure refrigerant from the refrigerant 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 refrigerant circuit 100. The compression capacity of the compressor 110 is controlled by the control section 300.

[0023] (2-1-2) First Heat Exchanger 120 The first heat exchanger 120 exchanges heat between the refrigerant filled in the refrigerant 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.

[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 inside. The flat tubes 93 function as heat transfer tubes, transferring heat transferred between the insertion fins 94 and the outdoor air to the refrigerant flowing inside. The flat tubes 93 have a plurality of through-holes aligned in a predetermined direction, through which the refrigerant passes to exchange heat 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 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 (not shown) 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 in the insertion fins 94 roughly matches the outer shape of the cross section of the flat tubes 93.

[0030] 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).

[0031] 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.

[0032] 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 refrigerant passing through the interiors of the plurality of flat tubes 93 collects in the headers 91, 92. A partition plate that separates the interior space may be formed inside the headers 91, 92.

[0033] (2-1-3) Third Heat Exchanger 130 The third heat exchanger 130 exchanges heat between the refrigerant filling the refrigerant circuit 100 and the water filling the water circuit 200. The third heat exchanger 130 has a refrigerant flow path 131 and a water flow path 132.

[0034] The refrigerant flowing through the refrigerant 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.

[0035] Water flowing through the water circuit 200 passes through the water flow path 132. 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.

[0036] The third heat exchanger 130 may be, but is not limited to, a plate-type heat exchanger.

[0037] 1, the switching mechanism 140 switches the direction of refrigerant flow in the refrigerant 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.

[0038] 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 third heat exchanger 130.

[0039] 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.

[0040] (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 third 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 third heat exchanger 130.

[0041] 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.

[0042] (2-2) Outdoor Unit 400 The outdoor unit 400 includes a fan 42 and a casing 41 .

[0043] (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.

[0044] (2-2-2) Casing 41 The casing 41 shown in FIGS. 2 and 3 houses the first heat exchanger 120 and the fan 42 .

[0045] 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 .

[0046] 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.

[0047] 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.

[0048] The side plates 414 are plate-like members that form the side surfaces of the casing 41. The side plates 414 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.

[0049] 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.

[0050] 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.

[0051] (2-3) Protective Unit 500 The protective unit 500 is disposed in a position within the refrigerant circuit such that, in the event of a refrigerant leak, the refrigerant will not reach undesirable locations, such as the air-conditioned space. Specifically, the protective unit 500 is disposed near the first heat exchanger 120. More specifically, the protective unit 500 is disposed near the first end 120a, the second end 120b, the flat tubes 93, the heat exchange unit 95, the header 91, or the header 92. In this specification, "nearby" means within 500 mm of the first heat exchanger 120. In this specification, "nearby" means, for example, within 500 mm of the first end 120a, which is the refrigerant inlet or outlet, or the second end 120b, which is the outlet, of the first heat exchanger 120. The protection unit 500 is arranged, for example, on the piping connecting the first heat exchanger 120 and the switching mechanism 140 or on the piping connecting the first heat exchanger 120 and the expansion mechanism 150 .

[0052] The protection unit 500 has a mechanism for detecting the refrigerant temperature or refrigerant pressure. A known mechanism for detecting the refrigerant temperature or refrigerant pressure may be employed. The mechanism for detecting the refrigerant temperature or refrigerant pressure may be included in the protection unit 500 or may be located remotely from the protection unit 500. If located remotely from the protection unit 500, the mechanism for detecting the refrigerant temperature or refrigerant pressure is preferably located at a location in the refrigerant circuit where the refrigerant pressure is highest. The mechanism for detecting the refrigerant temperature or refrigerant pressure is located, for example, near the first end 120a or the second end 120b, which is the refrigerant inlet or outlet of the first heat exchanger 120. In this specification, "nearby" means within 500 mm of the first end 120a or the second end 120b. The mechanism for detecting the refrigerant temperature or refrigerant pressure is located, for example, in the piping connecting the first heat exchanger 120 and the expansion mechanism 150 or the piping connecting the first heat exchanger 120 and the switching mechanism 140.

[0053] The protective part 500 is not particularly limited, but may be, for example, a safety valve having a rupture disc. A known rupture disc may be used, for example, one that buckles and reverses at the limit of the tensile strength or buckling strength of the material to burst open. The protective part 500 ruptures before the refrigerant pressure reaches a pressure corresponding to the spontaneous ignition temperature of the refrigerant, or before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant.

[0054] The protection unit 500 releases the refrigerant outside the refrigerant circuit before the refrigerant pressure reaches a pressure corresponding to the spontaneous ignition temperature of the refrigerant or before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant. "Outside the refrigerant circuit" refers to a space outside the refrigerant circuit 100, excluding the space to be air-conditioned. For example, "outside the refrigerant circuit" refers to the outdoor air (atmosphere).

[0055] "Before the refrigerant pressure reaches a pressure equivalent to the spontaneous ignition temperature of the refrigerant" refers to when the refrigerant pressure reaches a pressure equivalent to a temperature of the spontaneous ignition temperature of the refrigerant multiplied by (0.5 to 0.9). Note that the spontaneous ignition temperature is expressed in degrees Celsius. When the refrigerant is R290, the pressure equivalent to a temperature of the spontaneous ignition temperature of the refrigerant multiplied by (0.5 to 0.9) is, in detail, 6.5 to 9.0 MPa.

[0056] "Before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant" refers to when the refrigerant temperature reaches a temperature that is the spontaneous ignition temperature of the refrigerant multiplied by (0.5 to 0.9). Note that the spontaneous ignition temperature is expressed in degrees Celsius. When the refrigerant is R290, the refrigerant temperature that is the spontaneous ignition temperature of the refrigerant multiplied by (0.5 to 0.9) is specifically 200 to 300°C.

[0057] (2-4) Water Circuit 200 The water circuit 200 has a pump 210 and a second heat exchanger 220. The water circuit 200 is filled with water, which is a heat medium. The water exchanges heat with the refrigerant. Each part of the water circuit 200 is connected by piping.

[0058] (2-4-1) Pump 210 The pump 210 circulates the water filled in the water circuit 200 through the water 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 drawn into the water circuit 200 through the suction port 210a and discharges the water from the discharge port 210b back into the water circuit 200. The suction port 210a is connected to a second end 220b (described below) of the second heat exchanger 220. The discharge port 210b is connected to a second end 132b of the water flow path 132 of the third heat exchanger 130. The pump 210 is controlled by the control unit 300.

[0060] (2-4-2) Second Heat Exchanger 220 The second heat exchanger 220 exchanges heat between the water filled in the water circuit 200 and the air in the location where the second heat exchanger 220 is installed. The second 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 second heat exchanger 220. The second end 220b functions as an outlet for water flowing out of the second heat exchanger 220. The first end 220a is connected to a first end 132a of the water flow path 132 of the third heat exchanger 130.

[0061] The second heat exchanger 220 is installed in the space to be air-conditioned.

[0062] (2-5) Control Unit 300 Fig. 5 is a block diagram of the control unit 300. The control unit 300 controls each device in the refrigerant circuit 100 to cause the refrigerant 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.

[0063] 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.

[0064] (3) Overall Operation The control unit 300 controls each device during cooling operation and heating operation as described below.

[0065] (3-1) Cooling operation When the refrigeration cycle device 1 is instructed to perform cooling operation, the control unit 300 starts operation of the compressor 110 and the pump 210, sets the switching mechanism 140 to the first state, and controls the opening degree of the expansion mechanism 150.

[0066] (3-1-1) Refrigerant 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.

[0067] 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.

[0068] 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 third 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.

[0069] 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 third heat exchanger 130 functions as an evaporator.

[0070] The low-pressure refrigerant flowing out of the third 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 port 110a.

[0071] (3-1-2) Water Circuit 200 When the pump 210 starts operating, the refrigerant filled in the water circuit 200 is drawn in through the suction port 210a and then discharged from the discharge port 210b.

[0072] The water flowing out from the discharge port 210b flows into the water flow path 132 of the third 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.

[0073] The water flowing out of the third heat exchanger 130 flows into the second heat exchanger 220 from the first end 220a. The water flowing into the second heat exchanger 220 exchanges heat with the air in the location where the second heat exchanger 220 is installed, thereby cooling the air in the space to be air-conditioned.

[0074] The water that has exchanged heat with the air in the location where the second heat exchanger 220 is installed flows out from the second end 220b and is then sucked into the pump 210 again through the suction port 210a.

[0075] (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 140 to the second state, and controls the opening degree of the expansion mechanism 150.

[0076] (3-2-1) Refrigerant 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.

[0077] 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 third heat exchanger 130 from the second end 131b. The refrigerant that has flowed into the third 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 third heat exchanger 130 functions as a radiator.

[0078] The high-pressure refrigerant flowing out of the third 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.

[0079] 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.

[0080] 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.

[0081] (3-2-2) Water Circuit 200 When the pump 210 starts operating, the water filled in the water circuit 200 is sucked in through the suction port 210a and then discharged from the discharge port 210b.

[0082] The water flowing out from the discharge port 210b flows into the water flow path 132 of the third 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 heated), and then flows out from the first end 132a.

[0083] The water flowing out of the third heat exchanger 130 flows into the second heat exchanger 220 from the first end 220a. The water flowing into the second heat exchanger 220 exchanges heat with the air in the location where the second heat exchanger 220 is installed. This heats the air in the space to be air-conditioned.

[0084] The water that has exchanged heat with the air in the location where the second heat exchanger 220 is installed flows out from the second end 220b and is then sucked into the pump 210 again through the suction port 210a.

[0085] (4) Features (4-1) The refrigeration cycle apparatus 1 of this embodiment includes a protection unit 500. The protection unit 500 is disposed in the refrigerant circuit 100. The protection unit 500 releases the refrigerant out of the refrigerant circuit before the refrigerant pressure reaches a pressure corresponding to the spontaneous ignition temperature of the refrigerant, or before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant.

[0086] In the refrigeration cycle apparatus 1, the pressure of a flammable refrigerant in the refrigerant 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 highly flammable refrigerant to be released into the air-conditioned space. In this embodiment, the protection unit 500 releases the refrigerant out of the refrigerant circuit before the refrigerant pressure reaches a pressure corresponding to the refrigerant's autoignition temperature or before the refrigerant temperature reaches the refrigerant's autoignition temperature. Therefore, in the event of an abnormal pressure state, the protection unit 500 ruptures first. This allows the refrigerant to be released out of the refrigerant circuit, i.e., into the air (atmosphere). As a result, it is possible to suppress the release and combustion of the refrigerant in undesirable locations, such as the air-conditioned space.

[0087] (4-2) Here, the refrigerant circuit 100 includes a heat exchanger 120. The heat exchanger 120 is disposed outdoors. The protection unit 500 is disposed near the heat exchanger 120. Therefore, in an abnormal pressure state, the refrigerant can be reliably released into the air (atmosphere).

[0088] (4-3) Here, the protection part 500 is a safety valve having a rupture disc. In an abnormal pressure state, the protection part 500 itself can rupture, releasing the refrigerant into the air (atmosphere).

[0089] (4-4) Here, the highly flammable refrigerant is R290.

[0090] (4-5) Here, "before the refrigerant pressure reaches a pressure equivalent to the spontaneous ignition temperature of the refrigerant" refers to when the refrigerant pressure reaches a pressure equivalent to a temperature of the spontaneous ignition temperature of the refrigerant multiplied by (0.5 to 0.9). If the refrigerant pressure reaches a pressure equivalent to a temperature equal to or higher than 0.5 times the spontaneous ignition temperature of the refrigerant before reaching a pressure equivalent to the spontaneous ignition temperature of the refrigerant, the refrigeration cycle device 1 can be used without rupturing the protective unit 500 during normal use. If the refrigerant pressure reaches a pressure equivalent to a temperature equal to or lower than 0.9 times the spontaneous ignition temperature of the refrigerant, the protective unit 500 is more likely to rupture in an abnormal pressure state, thereby releasing the refrigerant out of the refrigerant circuit.

[0091] (4-6) Here, "before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant" refers to when the refrigerant temperature reaches a temperature of the spontaneous ignition temperature of the refrigerant × (0.5 to 0.9). If the refrigerant temperature reaches a temperature equal to or higher than 0.5 × the spontaneous ignition temperature of the refrigerant before reaching the spontaneous ignition temperature of the refrigerant, the refrigeration cycle apparatus 1 can be used without rupturing the protective unit 500 during normal use. If the refrigerant temperature reaches a temperature equal to or lower than 0.9 × the spontaneous ignition temperature of the refrigerant before reaching the spontaneous ignition temperature of the refrigerant, the protective unit 500 is likely to rupture in an abnormal pressure state, making it easier for the refrigerant to be released outside the refrigerant circuit.

[0092] (5) Modifications (5-1) Modification A In the above embodiment, the protection unit 500 is disposed near the first heat exchanger 120, but this is not particularly limited. The protection unit 500 may be disposed in another location as long as the refrigerant is not released into an undesirable location such as the air-conditioned space. The protection unit 500 may be disposed in the first heat exchanger 120, for example.

[0093] (5-2) Modification B When the protective part 500 is disposed in the first heat exchanger 120, the protective part 500 is disposed, for example, in the region R1 shown in Fig. 4 above the center of the height dimension of the first heat exchanger 120. In this case, R290, which has a higher specific gravity than air, can be easily dispersed without being retained near the ground.

[0094] (5-3) Modification C In the above embodiment, the machine chamber S2 is arranged next to the blower chamber S1 in the left-right direction, but this is not particularly limited. As shown in FIG. 6, the machine chamber S2 may be arranged above the blower chamber S1. In this case, the protection unit 500 may be arranged in the region R2 shown in FIG. 4, which is below the center of the height of the first heat exchanger 120. If the protection unit 500 is arranged below the center of the height of the first heat exchanger 120, it is easier to protect the machine chamber S2 even if the refrigerant is released and ignites.

[0095] (5-4) Modification D In the above modifications A to C, the protection unit 500 is disposed in the first heat exchanger 120, but this is not particularly limited. The protection unit 500 may be disposed in the blower chamber S1. In this case, even if the refrigerant is released, it is easier to disperse it.

[0096] (5-5) Modification E In the above embodiment, the protective part 500 is a safety valve having a rupture disc, but is not limited to this. The protective part 500 may be, for example, a fusible plug.

[0097] (5-6) Modification F In the above embodiment, in the third heat exchanger 130, the refrigerant flowing through the refrigerant circuit 100 exchanges heat with the water flowing through the water circuit 200, but this is not limited to this. In this modification, the refrigerant flowing through the refrigerant circuit 100 may exchange heat with the air in the target space. In this case, the water circuit 200 is omitted, and the third heat exchanger 130 is disposed in the target space.

[0098] 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.

[0099] REFRIGERATION CYCLE DEVICE 42 FAN 100 REFRIGERATOR CIRCUIT 110 COMPRESSOR 120 FIRST HEAT EXCHANGER 130 THIRD HEAT EXCHANGER 140 SWITCHING MECHANISM 200 WATER CIRCUIT 210 PUMP 220 SECOND HEAT EXCHANGER 300 CONTROL UNIT 400 OUTDOOR UNIT 500 PROTECTION UNIT S1 BLOWER ROOM S2 MACHINE ROOM

[0100] International Publication No. 2020-202560

Claims

1. A refrigeration cycle device (1), comprising: a refrigerant circuit (100) through which a highly flammable refrigerant circulates; and a protection unit (500) disposed within the refrigerant circuit, wherein the protection unit releases the refrigerant to the outside of the refrigerant circuit before the refrigerant pressure reaches a pressure equivalent to the spontaneous ignition temperature of the refrigerant, or before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant.

2. The refrigeration cycle device according to claim 1, wherein the refrigerant circuit includes a heat exchanger (120) that exchanges heat with air, and the protection unit is disposed near the heat exchanger or at the heat exchanger.

3. A refrigeration cycle apparatus as described in claim 1 or 2, further comprising an outdoor unit (400) having a machine chamber (S2) and a blower chamber (S1), wherein the protection part is disposed in the blower chamber.

4. The refrigeration cycle apparatus according to claim 2, wherein the protection portion is disposed above the center of the height dimension of the heat exchanger.

5. The refrigeration cycle apparatus according to claim 2, wherein the protection portion is disposed below the center of the height dimension of the heat exchanger.

6. The refrigeration cycle device according to any one of claims 1 to 5, wherein the protective part is a safety valve having a rupture disc.

7. The refrigeration cycle device according to any one of claims 1 to 6, wherein the protective part is a fusible plug.

8. The refrigeration cycle device according to any one of claims 1 to 7, wherein the highly flammable refrigerant is R290.

9. A refrigeration cycle device according to any one of claims 1 to 8, wherein "before the refrigerant pressure reaches a pressure equivalent to the spontaneous ignition temperature of the refrigerant" refers to the time when the refrigerant pressure reaches a pressure equivalent to a temperature of the spontaneous ignition temperature of the refrigerant x (0.5 to 0.9).

10. A refrigeration cycle device according to any one of claims 1 to 9, wherein "before the refrigerant temperature reaches the spontaneous ignition temperature of the refrigerant" refers to the time when the refrigerant temperature reaches a temperature of the spontaneous ignition temperature of the refrigerant x (0.5 to 0.9).

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