Refrigeration cycle device

Abstract

A refrigeration cycle device (1) is provided with a refrigerant circuit (10) and a control unit (4). The refrigerant circuit (10) has a first heat exchanger (13). The first heat exchanger (13) exchanges heat between outdoor air and a refrigerant. The refrigerant circuit (10) circulates a refrigerant. The control unit (4) performs a defrosting operation for melting frost adhering to the first heat exchanger and a capability reduction operation for reducing the capability. The control unit (4) performs a capacity reduction operation when the index related to frosting satisfies a second condition, and performs a defrosting operation when the index related to frosting satisfies a first condition during the capacity reduction operation.

Description

Technical Field

[0001] This disclosure relates to a refrigeration cycle apparatus. Background Technology

[0002] Patent document 1 (Japanese Patent Application Publication No. 2018-91579) discloses that during heating operation, when there are specified conditions that require reducing frost formation, the air heated by the humidification heater of the humidification unit flows to the air outlet located near the outdoor heat exchanger. Summary of the Invention

[0003] The technical problem that the invention aims to solve

[0004] However, Patent Document 1 does not disclose how to suppress frost formation on the outdoor heat exchanger in a refrigeration cycle device that does not include a humidification unit.

[0005] Technical solutions adopted to solve technical problems

[0006] The first-view refrigeration cycle device includes a refrigerant circuit and a control unit. The refrigerant circuit has a first heat exchanger. The first heat exchanger performs heat exchange between outdoor air and refrigerant. The refrigerant circuit circulates refrigerant. The control unit performs defrost operation and capacity reduction operation. Defrost operation melts the frost adhering to the first heat exchanger. Capacity reduction operation reduces the capacity. The control unit performs capacity reduction operation when a second condition is met for frost-related indicators, and during capacity reduction operation, performs defrost operation when a first condition is met for frost-related indicators.

[0007] According to the first viewpoint of the refrigeration cycle device, before the defrosting operation to melt the frost adhering to the first heat exchanger that exchanges heat with the outside air, a capacity reduction operation is performed to reduce the capacity of the refrigeration cycle device if a second condition related to frost formation is met. By performing this capacity reduction operation, frost formation on the first heat exchanger can be suppressed.

[0008] The second viewpoint's refrigeration cycle device is based on the first viewpoint's refrigeration cycle device, and the refrigerant includes R290.

[0009] Because R290 is a low-pressure refrigerant, the size of the first heat exchanger is increased, resulting in longer defrosting operation time. However, in the second viewpoint refrigeration cycle unit, even when using a refrigerant containing R290, frosting on the first heat exchanger can be suppressed by operating with reduced capacity. Therefore, even when using a refrigerant containing R290, frosting on the first heat exchanger can be suppressed by operating with reduced capacity, thus reducing the frequency of defrosting operation.

[0010] The third viewpoint's refrigeration cycle device is based on the first or second viewpoint's refrigeration cycle device, with the first heat exchanger being a microchannel heat exchanger.

[0011] Microchannel heat exchangers are prone to frost formation. However, in the refrigeration cycle unit of the third viewpoint, even if such a microchannel heat exchanger is used in the first heat exchanger that exchanges heat with the outside air, frost formation in the first heat exchanger can be suppressed by operating it with reduced capacity.

[0012] The fourth viewpoint's refrigeration cycle device is based on any of the first to third viewpoints, with the refrigerant circuit also including a second heat exchanger. The second heat exchanger facilitates heat exchange between the refrigerant and water. The refrigeration cycle device also includes a water circuit and a heat source. The water circuit supplies water flowing through the second heat exchanger. The heat source heats the water.

[0013] In the fourth viewpoint's refrigeration cycle device, when operating with reduced capacity, if the water temperature in the water circuit is lower than the target outlet water temperature, a heat source can heat the water. Therefore, it is possible to suppress frost formation while also preventing the water temperature from dropping.

[0014] The fifth viewpoint's refrigeration cycle unit is based on the fourth viewpoint's refrigeration cycle unit, and the refrigerant circuit also includes a compressor. The control unit reduces capacity by decreasing the compressor's capacity or lowering the target outlet water temperature.

[0015] In the fifth viewpoint's refrigeration cycle unit, the capacity of the refrigeration cycle unit is reduced by decreasing the compressor's capacity or lowering the target outlet water temperature. Therefore, a refrigeration cycle unit that suppresses frost formation can be easily implemented.

[0016] The sixth viewpoint's refrigeration cycle device is based on the fourth or fifth viewpoint's refrigeration cycle device, with the control unit activating the heat source when the capacity is reduced.

[0017] In the sixth viewpoint of the refrigeration cycle device, even when the capacity reduction of the refrigeration cycle device causes the temperature of the water heated by the refrigerant in the second heat exchanger to be lower than the target outlet water temperature, the heat source can still heat the water. Thus, the insufficient capacity during reduced-capacity operation is compensated by the heat source. Therefore, a refrigeration cycle device that suppresses both frost formation and water temperature drop can be easily realized.

[0018] The seventh viewpoint's refrigeration cycle device is based on the sixth viewpoint's refrigeration cycle device. When operating with reduced capacity, the amount of water heated by the refrigeration cycle device is greater than the amount of water heated by the heat source.

[0019] In the seventh viewpoint of the refrigeration cycle device, when the capacity is reduced during operation, the amount of water heated by the heat source will not exceed the amount of water heated by the refrigeration cycle device, thus suppressing the reduction in the efficiency of the refrigeration cycle device.

[0020] The refrigeration cycle device of the eighth viewpoint is based on the refrigeration cycle device of any of the fourth to seventh viewpoints, and the control unit activates the heat source during defrosting operation.

[0021] In the refrigeration circulation system of the eighth viewpoint, even when the water temperature drops during defrosting operation, the water can be heated by a heat source to suppress the decrease in comfort.

[0022] The refrigeration cycle device of the ninth viewpoint is based on the refrigeration cycle device of any of the first to eighth viewpoints, with the second condition being that the outside air temperature is above -10°C and below 7°C.

[0023] In the refrigeration cycle unit of the ninth viewpoint, the temperature of the outdoor air is used as a secondary condition for control, thus making it easy to control the operation with reduced capacity.

[0024] The refrigeration cycle device of the tenth point is based on the refrigeration cycle device of any of the first to eighth points, and the second condition is a state in which the capacity required for the outside air temperature exceeds the capacity to operate without frost forming on the first heat exchanger.

[0025] The condition where the required capacity to prevent frost formation exceeds the capacity required to prevent frost formation is due to a low external air temperature and a high capacity of the refrigeration cycle unit. In this case, the first heat exchanger is cooled and therefore becomes prone to frost formation. Therefore, in the refrigeration cycle unit of the tenth viewpoint, this condition is set to satisfy the second condition, thus enabling frost formation to be suppressed by operating with reduced capacity.

[0026] The refrigeration cycle device of the eleventh point is based on the refrigeration cycle device of any of the first to eighth points, with the second condition being that the evaporation temperature of the refrigerant in the first heat exchanger is more than a specified temperature lower than the dew point temperature, and the outside air temperature is below 2°C.

[0027] When the evaporation temperature is more than a specified temperature below the dew point temperature and the outside air temperature is 2°C or less, the first heat exchanger is cooled, and therefore, frost easily forms. Therefore, in the refrigeration cycle unit of the eleventh viewpoint, this state is set to satisfy the second condition, thereby suppressing frost formation by operating with reduced capacity.

[0028] The refrigeration cycle unit of the twelfth viewpoint is based on the refrigeration cycle unit of any of the first to eleventh viewpoints, but the maximum duration of defrosting operation is shorter than the maximum duration of capacity reduction operation.

[0029] In the refrigeration cycle unit of the twelfth viewpoint, by continuously operating at reduced capacity, the frequency of defrosting operation can be reduced, and even when defrosting operation is performed, its maximum duration can be shortened. Therefore, the time of reduced comfort caused by defrosting operation can be reduced.

[0030] The refrigeration cycle device of the thirteenth viewpoint is based on the refrigeration cycle device of any of the first to twelfth viewpoints. When the first condition is met during reduced capacity operation, the control unit switches to defrost operation.

[0031] In the refrigeration cycle unit of the thirteenth viewpoint, even when operating with reduced capacity, the control unit performs defrosting operation when the first condition is met. This helps to suppress the reduction in efficiency of the refrigeration cycle unit. Attached Figure Description

[0032] Figure 1 This is a schematic structural diagram of a refrigeration cycle apparatus according to one embodiment of the present disclosure.

[0033] Figure 2 This is a control block diagram of a refrigeration cycle unit.

[0034] Figure 3 It is a diagram showing the operation (refrigerant flow) of a refrigeration cycle unit during refrigeration.

[0035] Figure 4 This is a diagram showing the operation (refrigerant flow) of a refrigeration cycle unit during heating.

[0036] Figure 5 This is a diagram showing the control flow during the defrosting and refrigeration operation of a refrigeration cycle unit.

[0037] Figure 6 This is a diagram illustrating the control flow during the operation of a refrigeration cycle unit with reduced capacity.

[0038] Figure 7 This diagram illustrates the second condition of variation example four.

[0039] Figure 8 This diagram illustrates the second condition of variation example five. Detailed Implementation

[0040] (1) Overall structure

[0041] Figure 1The refrigeration cycle apparatus 1 shown in one embodiment of the present disclosure is an apparatus that performs a vapor compression refrigeration cycle in the refrigerant circuit 10 to cool or heat water circulating in the water circuit 30, and uses the water to refrigerate or heat the target space.

[0042] The refrigeration cycle unit 1 includes a heat source unit 2 and a utilization unit 3. The heat source unit 2 and the utilization unit 3 are connected. In this embodiment, there is one heat source unit 2 and one utilization unit 3.

[0043] Furthermore, the refrigeration cycle unit 1 includes a refrigerant circuit 10, a water circuit 30, and a control unit 4. The refrigerant circuit 10 supplies refrigerant circulation. The water circuit 30 supplies water circulation. The refrigerant circuit 10 is connected to the water circuit 30. The control unit 4 performs heating operation, cooling operation, defrosting operation, and capacity reduction operation.

[0044] (2) Detailed structure

[0045] (2-1) Refrigerant circuit

[0046] The refrigerant circuit 10 is a circuit that supplies refrigerant circulation during normal operation such as heating operation and cooling operation, as well as during operation such as defrosting operation and capacity reduction operation to cope with frost formation on the first heat exchanger 13 (described later).

[0047] A refrigerant is sealed in the refrigerant circuit 10. The refrigerant is not particularly limited, but here it is a flammable refrigerant. A flammable refrigerant is one that is capable of combustion. Examples of flammable refrigerants include hydrocarbon refrigerants, R1234yf, R1234ze, R32, etc., which are classified as highly flammable (A3) in ISO 817. In this embodiment, R290 (propane) is included. The refrigerant can be a single refrigerant of R290 or a mixture of R290 and other refrigerants. Furthermore, the refrigerant includes refrigeration oil. Examples of refrigeration oil include PAG (polyalkylene glycol).

[0048] The refrigerant circuit 10 mainly includes a compressor 11, a switching mechanism 12, a first heat exchanger 13, a first expansion mechanism 14, a second heat exchanger 15, a liquid pipe 16, a gas-liquid heat exchanger 17, a branch pipe 18, an injection pipe 19, a second expansion mechanism 20, an energy-saving heat exchanger 21, a first valve 22, a second valve 23, a third valve 24, a fourth valve 25, and a storage tank 26.

[0049] (2-1-1) Compressor

[0050] Compressor 11 compresses the low-pressure refrigerant in the refrigeration cycle to high pressure. Here, compressor 11 is a two-stage compressor that draws in the low-pressure refrigerant in the refrigeration cycle and compresses it to the intermediate pressure in the refrigeration cycle, and then further compresses the intermediate-pressure refrigerant to high pressure and discharges it.

[0051] The compressor 11 includes a housing 11a, a first compression element 11b, a second compression element 11c, a drive motor 11d, a first suction section 11e, a second suction section 11f, and a discharge section 11g.

[0052] The housing 11a houses the first compression element 11b and the second compression element 11c. The first compression element 11b and the second compression element 11c are connected to a single drive shaft (not shown). During operation of the compressor 11, the drive motor 11d drives the first compression element 11b and the second compression element 11c to rotate via the drive shaft. In other words, the compressor 11 has a single-shaft, two-stage compression structure.

[0053] The first suction section 11e draws in low-pressure refrigerant from the refrigerant circuit 10. The second suction section 11f draws in intermediate-pressure refrigerant from the refrigerant circuit 10. The discharge section 11g discharges high-pressure refrigerant into the refrigerant circuit 10. The second suction section 11f is an example of a suction section.

[0054] The second suction section 11f has a check valve (not shown) that allows refrigerant to flow from the outside of the housing 11a into the inside and restricts refrigerant from flowing from the inside of the housing 11a outward.

[0055] The first compression element 11b compresses the refrigerant drawn in by the first suction section 11e to an intermediate pressure and discharges it to the second compression element 11c. The second compression element 11c compresses the intermediate-pressure refrigerant discharged by the first compression element 11b together with the intermediate-pressure refrigerant drawn in by the second suction section 11f to a high pressure and discharges it to the discharge section 11g.

[0056] Furthermore, the structure of compressor 11 is not limited to a single-shaft two-stage compression structure. For example, compressor 11 can also be constructed using a compression element driven by another drive motor.

[0057] (2-1-2) Switching mechanism

[0058] The switching mechanism 12 switches the direction of refrigerant flow in the refrigerant circuit 10 between two states. The switching mechanism 12 is a four-way reversing valve. The switching mechanism 12 has a first port P1, a second port P2, a third port P3, and a fourth port P4.

[0059] Switching mechanism 12 in the first state ( Figure 1 The state shown by the solid line) and the second state ( Figure 1The switching mechanism 12 switches between the states shown by the dashed lines. In the first state, the switching mechanism 12 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 12 connects the first port P1 to the fourth port P4 and connects the second port P2 to the third port P3.

[0060] The switching mechanism 12 is not limited to a four-way reversing valve; for example, it can also be composed of multiple solenoid valves and a refrigerant flow path combination.

[0061] (2-1-3) First heat exchanger

[0062] The first heat exchanger 13 is an air heat exchanger. The first heat exchanger 13 exchanges heat between the refrigerant flowing inside it and the outside air (outdoor air) supplied from the first fan 13a. The first heat exchanger 13 functions as a refrigerant radiator during cooling operation and as a refrigerant evaporator during heating operation. The first heat exchanger 13 employs a heat exchanger suitable for its application, such as a cross-fin heat exchanger or a microchannel heat exchanger. In this embodiment, the first heat exchanger 13 is a microchannel heat exchanger.

[0063] The first heat exchanger 13 has a refrigerant flow path (not shown). The refrigerant flow path of the first heat exchanger 13 is located in the refrigerant circuit 10.

[0064] For ease of explanation, in heating operation, the end of the refrigerant flow path of the first heat exchanger 13 into which the refrigerant flows in is referred to as the first end 13aa, and the end of the refrigerant flow path into which the refrigerant flows out is referred to as the second end 13ab.

[0065] (2-1-4) First expansion mechanism

[0066] The first expansion mechanism 14 reduces the pressure of the passing refrigerant to a low pressure. The first expansion mechanism 14 is located on the liquid line 16. The first expansion mechanism 14 is, for example, an electrically operated expansion valve.

[0067] (2-1-5) Second heat exchanger

[0068] The second heat exchanger 15 is a water heat exchanger. In this embodiment, the second heat exchanger 15 performs heat exchange between the refrigerant flowing in the refrigerant circuit 10 and the water flowing in the water circuit 30. The second heat exchanger 15 functions as an evaporator for the refrigerant during cooling operation and as a radiator for the refrigerant during heating operation. The second heat exchanger 15 can be a heat exchanger suitable for the application, such as a plate heat exchanger.

[0069] The second heat exchanger 15 has a refrigerant flow path 15a and a water flow path 15b. The refrigerant flow path 15a is provided in the refrigerant circuit 10. The water flow path 15b is provided in the water circuit 30. The refrigerant flowing in the refrigerant flow path 15a and the water flowing in the water flow path 15b exchange heat with each other. The water that has exchanged heat with the refrigerant circulates in the water circuit 30 to heat or cool the air in the target space.

[0070] For ease of explanation, in heating operation, the end of the refrigerant flow path 15a into which the refrigerant flows in is referred to as the first end 15aa, and the end of the refrigerant flow path 15a into which the refrigerant flows out is referred to as the second end 15ab.

[0071] (2-1-6) Liquid tube

[0072] Liquid pipe 16 connects the radiator (first heat exchanger 13 during cooling operation and second heat exchanger 15 during heating operation) to the evaporator (second heat exchanger 15 during cooling operation and first heat exchanger 13 during heating operation). Here, liquid pipe 16 connects the first end 13aa of the refrigerant flow path of the first heat exchanger 13 to the second end 15ab of the refrigerant flow path 15a of the second heat exchanger 15.

[0073] (2-1-7) Gas-liquid heat exchanger

[0074] The gas-liquid heat exchanger 17 exchanges heat between the refrigerant flowing from the radiator (second heat exchanger 15 during heating operation) to the evaporator (first heat exchanger 13 during heating operation) and the refrigerant flowing from the evaporator to the compressor 11. The gas-liquid heat exchanger 17 is a pre-cooling heat exchanger that cools the refrigerant flowing from the radiator to the evaporator. The gas-liquid heat exchanger 17 has a first heat transfer tube 17a and a second heat transfer tube 17b.

[0075] The first heat transfer pipe 17a is through which refrigerant flows from the evaporator to the first suction section 11e of the compressor 11. One end of the first heat transfer pipe 17a is connected to the third port P3 of the switching mechanism 12. The other end of the first heat transfer pipe 17a is connected to the first suction section 11e of the compressor 11 via the storage tank 26.

[0076] The second heat transfer tube 17b is through which the refrigerant flows from the radiator to the evaporator. Both ends of the second heat transfer tube 17b are connected to the branch tube 18.

[0077] In this embodiment, during heating operation, the gas-liquid heat exchanger 17 exchanges heat between the refrigerant passing through the first heat transfer tube 17a and the refrigerant passing through the second heat transfer tube 17b. Conversely, during cooling operation, the gas-liquid heat exchanger 17 does not exchange heat between the refrigerant passing through the first heat transfer tube 17a and the refrigerant passing through the second heat transfer tube 17b. Specifically, the refrigerant flows through both the first heat transfer tube 17a and the second heat transfer tube 17b during heating operation, but does not flow through the second heat transfer tube 17b during cooling operation.

[0078] (2-1-8) Branch pipe

[0079] The branch pipe 18 is a refrigerant flow path that branches off from the second heat exchanger 15 and the first expansion mechanism 14 in the liquid pipe 16 and connects to the second heat transfer pipe 17b of the gas-liquid heat exchanger 17. In other words, the branch pipe 18 has a second heat transfer pipe 17b in the middle.

[0080] One end of the second heat transfer tube 17b is connected to a branch pipe 18 that branches off from the side of the second heat exchanger 15. The other end of the second heat transfer tube 17b is connected to a branch pipe 18 that branches off from the side of the first expansion mechanism 14.

[0081] For ease of explanation, the part of the branch pipe 18 that branches off from the second heat exchanger 15 side of the liquid pipe 16 is sometimes referred to as the first branch section 18a, and the part of the branch pipe 18 that branches off from the first expansion mechanism 14 side of the liquid pipe 16 is sometimes referred to as the second branch section 18b.

[0082] (2-1-9) Injection pipe

[0083] The jet pipe 19 will be drawn from the radiator ( Figure 1 The middle section is the second heat exchanger 15) flowing to the evaporator ( Figure 1 A portion of the refrigerant in the first heat exchanger 13 is branched off and delivered to the compressor 11. Here, the injection pipe 19 branches off from the liquid pipe 16 and connects to the first suction section 11e and the second suction section 11f of the compressor 11. Therefore, the injection pipe 19 enables the refrigerant to merge with the low-pressure refrigerant of the compressor 11, and also enables the refrigerant to merge with the intermediate-pressure refrigerant between the high and low pressure of the compressor 11.

[0084] Injector 19 from radiator ( Figure 1 The jet pipe 19 branches off between the second heat exchanger 15 and the energy-saving heat exchanger 21 during refrigerant flow in heating operation. In other words, the jet pipe 19 branches off from a position downstream of the radiator and upstream of the energy-saving heat exchanger 21 during heating operation.

[0085] exist Figure 1In the middle, the injection tube 19 has a first part 19a, a second part 19b, a third part 19c and a fourth part 19d.

[0086] The first part 19a branches off from the liquid pipe 16 and shares a branch pipe 18. Here, the first part 19a branches off from the first branch portion 18a in the liquid pipe 16.

[0087] The second section 19b allows the refrigerant flowing through the first section 19a to flow into the first heat transfer tube 21a of the energy-saving heat exchanger 21 (described later). The second section 19b is connected to the end of the first section 19a opposite to the branch point from the liquid pipe 16 (here, the first branch point 18a). The second section 19b has the first heat transfer tube 21a of the energy-saving heat exchanger 21 located in the middle.

[0088] The third part 19c allows the refrigerant flowing through the first heat transfer tube 21a of the energy-saving heat exchanger 21 to flow into the first suction section 11e of the compressor 11. The third part 19c connects the end of the second part 19b on the opposite side to the first part 19a to the first suction section 11e of the compressor 11.

[0089] The fourth part 19d allows the refrigerant flowing through the first heat transfer tube 21a of the energy-saving heat exchanger 21 to flow into the second suction section 11f of the compressor 11. The fourth part 19d connects the end of the second part 19b opposite to the first part 19a to the second suction section 11f of the compressor 11.

[0090] (2-1-10) Second expansion mechanism

[0091] The second expansion mechanism 20 reduces the pressure of the refrigerant passing through the injection pipe 19 to an intermediate pressure. The second expansion mechanism 20 is disposed in the second part 19b of the injection pipe 19 between the connection portion connected to the first part 19a and the energy-saving heat exchanger 21.

[0092] The second expansion mechanism 20 is, for example, an on / off valve such as a solenoid valve, or a flow control valve such as an electric expansion valve. In this embodiment, the second expansion mechanism 20 is an electric expansion valve.

[0093] (2-1-11) Energy-saving heat exchanger

[0094] The energy-saving heat exchanger 21 exchanges heat between the refrigerant, after it has passed through the injection pipe 19 and been depressurized by the second expansion mechanism 20, and the refrigerant flowing from the radiator to the evaporator. The energy-saving heat exchanger 21 has a first heat transfer pipe 21a and a second heat transfer pipe 21b. The energy-saving heat exchanger 21 exchanges heat between the refrigerant passing through the first heat transfer pipe 21a and the refrigerant passing through the second heat transfer pipe 21b.

[0095] The first heat transfer tube 21a supplies refrigerant flowing through the injection tube 19. The first heat transfer tube 21a is disposed in the injection tube 19. One end of the first heat transfer tube 21a is connected to the second expansion mechanism 20 via the injection tube 19. The other end of the first heat transfer tube 21a is connected to the first suction section 11e and the second suction section 11f of the compressor 11 via the injection tube 19.

[0096] The second heat transfer tube 21b supplies refrigerant that flows through the branch pipe 18. The second heat transfer tube 21b is located on the branch pipe 18. One end of the second heat transfer tube 21b is connected to the first valve 22 via the branch pipe 18. The other end of the second heat transfer tube 21b is connected to the second heat transfer tube 17b of the gas-liquid heat exchanger 17 via the branch pipe 18.

[0097] In this embodiment, during heating operation, the energy-saving heat exchanger 21 exchanges heat between the refrigerant passing through the first heat transfer tube 21a and the refrigerant passing through the second heat transfer tube 21b. Conversely, during cooling operation, the energy-saving heat exchanger 21 does not exchange heat between the refrigerant passing through the first heat transfer tube 21a and the refrigerant passing through the second heat transfer tube 21b. Specifically, the refrigerant flows through both the first heat transfer tube 21a and the second heat transfer tube 21b during heating operation, but does not flow through either the first heat transfer tube 21a or the second heat transfer tube 21b during cooling operation.

[0098] (2-1-12) First valve

[0099] The first valve 22, located in the first portion 19a of the injection pipe 19, restricts the flow of refrigerant from the liquid pipe 16 to the energy-saving heat exchanger 21. The first valve 22 is an on-off valve that switches between an open state and a closed state.

[0100] The first valve 22 is opened during heating operation and closed during cooling operation.

[0101] (2-1-13) Second valve

[0102] The second valve 23, located in the third section 19c of the injection pipe 19, restricts the inflow of refrigerant through the injection pipe 19 into the first suction section 11e of the compressor 11. The second valve 23 is an on-off valve that switches between an open state and a closed state.

[0103] The second valve 23 is closed during heating operation and open during cooling operation.

[0104] (2-1-14) Third valve

[0105] The third valve 24 is located in the branch pipe 18 and restricts the flow of refrigerant from the second branch 18b to the second heat transfer pipe 17b. The third valve 24 is provided in the branch pipe 18. The third valve 24 is a check valve that restricts the flow of refrigerant from the second branch 18b to the second heat transfer pipe 17b and allows the flow of refrigerant from the second heat transfer pipe 17b to the second branch 18b.

[0106] (2-1-15) Fourth valve

[0107] A fourth valve 25 is located in the liquid pipe 16 to restrict the flow of refrigerant from the first branch 18a to the second branch 18b. The fourth valve 25 is disposed in the liquid pipe 16 between the first branch 18a and the second branch 18b. The fourth valve 25 is a check valve that restricts the flow of refrigerant from the first branch 18a to the second branch 18b and allows the flow of refrigerant from the second branch 18b to the first branch 18a.

[0108] (2-1-16) Storage tank

[0109] The storage tank 26 is connected between the switching mechanism 12 and the first suction section 11e of the compressor 11. Here, the storage tank 26 is located in the refrigerant flow path that connects the other end of the first heat transfer tube 17a of the gas-liquid heat exchanger 17 to the first suction section 11e of the compressor 11. The storage tank 26 separates the refrigerant flowing out of the first heat transfer tube 17a of the gas-liquid heat exchanger 17 and flowing into the first suction section 11e of the compressor 11 into gaseous refrigerant and liquid refrigerant.

[0110] (2-2) Water circuit

[0111] Water circuit 30 is a circuit for supplying water during normal operation such as heating operation and cooling operation, as well as during operation such as defrosting operation and capacity reduction operation to cope with frost formation on the first heat exchanger 13.

[0112] The water circuit 30 includes a second heat exchanger 15, a pump 31, a gas-liquid separator 32, a third heat exchanger 33, and a heat source 34.

[0113] (2-2-1) Second heat exchanger

[0114] The water flow path 15b of the second heat exchanger 15 constitutes the water circuit 30.

[0115] (2-2-2) Pump

[0116] Pump 31 applies a specified pressure to the water it draws in and discharges it. Pump 31 causes the water filling the water circuit 30 to circulate in a certain direction within the water circuit 30.

[0117] (2-2-3) Gas-liquid separator

[0118] The gas-liquid separator 32 separates the refrigerant mixed in with the water piping connected to the second heat exchanger 15. The gas-liquid separator 32 is located downstream of the second heat exchanger 15. Here, the gas-liquid separator 32 is positioned between the outlet of the water flow path 15b of the second heat exchanger 15 and the inlet of the third heat exchanger 33.

[0119] (2-2-4) Third heat exchanger

[0120] The third heat exchanger 33 exchanges heat between the water flowing inside it and the indoor air supplied from the second fan 33a. The third heat exchanger 33 may be a heat exchanger suitable for the application, such as a radiator.

[0121] The third heat exchanger 33 has a water flow path (not shown). The water flow path of the third heat exchanger 33 is located in the water circuit 30.

[0122] (2-2-5) Heat source

[0123] Heat source 34 heats the water filling water circuit 30. Heat source 34 is a standby heater that heats the water flowing through water circuit 30 when the temperature is low. Here, the capacity of heat source 34 is less than half the capacity of refrigeration circulation unit 1.

[0124] Heat source 34 is located between the third heat exchanger 33 and the second heat exchanger 15. Here, heat source 34 is located between the third heat exchanger 33 and the gas-liquid separator 32. Heat source 34 can be a gas-fired boiler, electric heater, or other suitable heater for the application.

[0125] (2-3) Heat source machine

[0126] The heat source unit 2 is located in a space different from the space where heating or cooling is performed. Here, the heat source unit 2 is located outdoors (near the roof of a building or the exterior wall of a building, etc.). The heat source unit 2 includes the aforementioned refrigerant circuit 10, the first fan 13a, a portion of the aforementioned water circuit 30, and various sensors. Here, the heat source unit 2 includes a pump 31 as part of the water circuit 30 and a gas-liquid separator 32.

[0127] (2-3-1) First fan

[0128] The first fan 13a supplies outdoor air to the first heat exchanger 13. The first fan 13a is driven by a fan motor.

[0129] (2-3-2) Sensor

[0130] The heat source unit 2 is equipped with an outdoor temperature sensor 41 and an outlet water temperature sensor 42. The outdoor temperature sensor 41 detects the temperature of the outdoor air before it passes through the first heat exchanger 13. The outlet water temperature sensor 42 detects the temperature of the water after it passes through the second heat exchanger 15.

[0131] (2-4) Utilizing the machine

[0132] The heat source unit 3 is installed inside the building. The heat source unit 2 and the heat source unit 3 are thermally connected via a second heat exchanger 15. Here, the water circuit 30 of the heat source unit 3 is connected to the water flow path 15b of the second heat exchanger 15. The heat source unit 3 includes a portion of the aforementioned water circuit 30, a second fan 33a, and various sensors. Here, the heat source unit 3 includes a heat source 34 as part of the water circuit 30 and a third heat exchanger 33.

[0133] (2-4-1) Second fan

[0134] The second fan 33a supplies indoor air to the third heat exchanger 33. The second fan 33a is driven by a fan motor.

[0135] (2-4-2) Sensor

[0136] The machine 3 is equipped with an indoor temperature sensor 43, which detects the temperature of the air drawn in from the room and before passing through the third heat exchanger 33, i.e., the indoor temperature.

[0137] (2-5) Control Department

[0138] (2-5-1) Summary

[0139] The control unit 4 controls the components of the refrigeration cycle unit 1. For example... Figure 2 As shown, the control unit 4 is electrically connected to the compressor 11, switching mechanism 12, first expansion mechanism 14, second expansion mechanism 20, first fan 13a, second fan 33a, first valve 22, second valve 23, pump 31, heat source 34, outdoor temperature sensor 41, outlet water temperature sensor 42, and indoor temperature sensor 43 to send and receive signals. The control unit 4 acquires information such as the operating status of each device and the measured values ​​of each sensor. Based on the acquired information, the control unit 4 controls each device of the refrigeration cycle unit 1 to realize refrigeration operation, heating operation, defrosting operation, and capacity reduction operation.

[0140] The control unit 4 is implemented using a computer. The control unit 4 includes a control processing unit and a storage unit (both omitted from the diagram). A processor such as a CPU or GPU can be used in the control processing unit. The control processing unit reads a program stored in the storage unit and performs prescribed calculations according to the program. Furthermore, the control processing unit can write the calculation results to the storage unit or read information stored in the storage unit according to the program.

[0141] (2-5-2) Control during defrosting operation and capacity reduction operation

[0142] The following describes the control performed by the control unit 4 on the refrigeration cycle unit 1 during defrosting operation and capacity reduction operation.

[0143] Defrosting operation is an operation that melts the frost adhering to the first heat exchanger 13. During defrosting operation, the first heat exchanger 13 functions as a radiator. In this embodiment, the flow of refrigerant in the refrigerant circuit 10 during defrosting operation is the same as during refrigeration operation.

[0144] Capacity reduction operation is an operation used to prevent the system from switching to defrost operation during heating operation. In other words, capacity reduction operation is a heating operation to prevent frost formation. Capacity reduction operation reduces capacity during heating operation. Specifically, capacity reduction operation operates the refrigeration cycle unit 1 at a capacity lower than that required by the user unit 3. Therefore, in capacity reduction operation, the capacity to heat water flowing in water flow path 15b by the refrigerant flowing in refrigerant flow path 15a in the second heat exchanger 15 is reduced. The flow of refrigerant in the refrigerant circuit 10 during capacity reduction operation is the same as during heating operation.

[0145] The control unit 4 has a first condition and a second condition regarding the indicators related to frosting on the first heat exchanger 13. When the indicators related to frosting meet the first condition, the control unit 4 performs defrosting operation. When the indicators related to frosting meet the second condition, the control unit 4 performs capacity reduction operation. When the indicators related to frosting meet the first condition during capacity reduction operation, the control unit 4 switches to defrosting operation.

[0146] The first condition is that defrosting operation is required. The second condition is that defrosting operation is not required. The second condition is also the condition where the likelihood of frosting is lower compared to the first condition. Therefore, the second condition is true before the first condition is met.

[0147] The first condition differs from the second condition. However, the second condition is similar to the first condition. An indicator related to frost formation is, for example, the outside air temperature. The outside air temperature in the second condition is higher than that in the first condition, and preferably more than 2°C higher.

[0148] The second condition of this embodiment is that the outside air temperature is above -10°C and below 7°C. Furthermore, the first condition is that the outside air temperature is below -10°C.

[0149] Furthermore, the first condition is not limited to the outside air temperature being below a specified value; it can also include conditions such as a specified time elapsed since the last defrosting operation, the temperature of the first heat exchanger 13 being below a specified value, and the evaporation pressure or evaporation temperature of the refrigerant in the refrigerant circuit 10 being below a specified value. Similarly, the second condition is not limited to the outside air temperature being below a specified value; it can also include conditions such as the temperature of the first heat exchanger 13 being below a specified value lower than the temperature of the first condition, and the evaporation pressure or evaporation temperature of the refrigerant in the refrigerant circuit 10 being below a specified value lower than the temperature of the first condition. Moreover, the parameters (indicators) of the first condition and the parameters (indicators) of the second condition can also be different.

[0150] Here, when the refrigeration cycle unit 1 is started, the control unit 4 performs a capacity reduction operation if the second condition is met but the first condition is not. Furthermore, when the refrigeration cycle unit 1 is started, the control unit 4 performs a defrost operation if the first condition is met but the second condition is not met. For example, at very low temperatures such as -20°C, defrost operation is performed without capacity reduction. For example, at low temperatures such as 2°C but no frost adheres to the first heat exchanger 13, capacity reduction operation is performed, and then defrost operation is performed when frost adheres to the first heat exchanger 13.

[0151] During capacity reduction operation, control unit 4 performs capacity reduction control to reduce the heat pump capacity. In this embodiment, control unit 4 performs capacity reduction operation by reducing the capacity of compressor 11 or reducing the target outlet water temperature. Specifically, during capacity reduction operation, control unit 4 sets the capacity of compressor 11 to be lower than the capacity of compressor 11 set based on the indoor air temperature required by the user unit 3 during heating operation. More specifically, control unit 4 sets the motor speed of compressor 11 during capacity reduction operation to be lower than the speed during heating operation. Furthermore, during capacity reduction operation, control unit 4 sets the target outlet water temperature of the water flowing from the water flow path 15b of the second heat exchanger 15 to a temperature lower than the target outlet water temperature set based on the indoor air temperature required by the user unit 3 during heating operation. More specifically, control unit 4 sets the target outlet water temperature during capacity reduction operation to be a few degrees lower than that during heating operation.

[0152] During reduced capacity operation, the reduced capacity of the refrigeration cycle unit 1 causes the temperature of the water heated by the refrigerant in the second heat exchanger 15 to fall below the target outlet water temperature. Therefore, during reduced capacity operation, the control unit 4 activates the heat source 34 to heat the water flowing into the third heat exchanger 33 in order to compensate for the target outlet water temperature. The control unit 4 can activate the heat source 34 when switching from heating operation to reduced capacity operation, or it can activate the heat source 34 after a predetermined time has elapsed since switching from heating operation to reduced capacity operation.

[0153] During reduced capacity operation, the amount of water heated by the refrigeration cycle unit 1 is greater than the amount of water heated by the heat source 34. Specifically, the control unit 4 controls the heat source 34 during reduced capacity operation to ensure that the amount of water heated by the refrigerant in the second heat exchanger 15 is greater than the amount of water heated by the heat source 34. When the amount of water heated by the heat source 34 exceeds the amount heated by the refrigeration cycle unit 1, the coefficient of performance (COP) decreases. Therefore, when the amount of water heated by the heat source 34 is greater than the amount heated by the refrigeration cycle unit 1, the control unit 4 can switch from reduced capacity operation to defrost operation regardless of the first condition.

[0154] Control unit 4 controls the maximum duration of defrosting operation and the maximum duration of capacity reduction operation. In this embodiment, the maximum duration of defrosting operation is shorter than the maximum duration of capacity reduction operation. The maximum duration of defrosting operation is, for example, 20 minutes. There is no upper limit to the maximum duration of capacity reduction operation. In other words, the maximum duration of capacity reduction operation is set to indefinite.

[0155] (3) Actions

[0156] Reference Figures 1-6 The operation of the refrigeration cycle unit 1 will be explained. The refrigeration cycle unit 1 performs refrigeration operation, heating operation, defrosting operation, and capacity reduction operation. The operation of the refrigeration cycle unit 1, including the above operations, is performed by the control unit 4.

[0157] (3-1) Refrigeration operation

[0158] The following is for reference Figure 3 The operation of the refrigeration cycle unit 1 during refrigeration is explained. Figure 3 The refrigeration operation shown is carried out by the control unit 4, which receives the refrigeration operation command, and controls the operation of the compressor 11, switching mechanism 12, first expansion mechanism 14, second expansion mechanism 20, first fan 13a, first valve 22, second valve 23, pump 31, second fan 33a, heat source 34, etc.

[0159] Specifically, the control unit 4 starts the compressor 11 and controls the speed of the drive motor 11d of the compressor 11. The switching mechanism 12 is controlled to a second state. The opening degree of the first expansion mechanism 14 is controlled. The control unit 4 sets the target superheat of the refrigerant flowing out of the first end 15aa of the second heat exchanger 15, for example, based on the target outlet temperature of the water flowing out of the water flow path 15b of the second heat exchanger 15. Then, the control unit 4 controls the opening degree of the first expansion mechanism 14 so that the superheat of the refrigerant flowing out of the second heat exchanger 15 is close to the target superheat. The second expansion mechanism 20 is controlled to be fully open or nearly fully open (hereinafter simply referred to as fully open). The first valve 22 is controlled to be closed. The second valve 23 is controlled to be open.

[0160] In addition, control unit 4 starts pump 31. Heat source 34 is controlled to be inactive.

[0161] (3-1-1) Refrigerant circuit

[0162] When compressor 11 starts operating, low-pressure gaseous refrigerant in the refrigeration cycle is drawn in from the first suction section 11e. The first compression element 11b compresses the low-pressure refrigerant drawn in from the first suction section 11e to an intermediate pressure and discharges it to the second compression element 11c. The second compression element 11c compresses the intermediate-pressure refrigerant discharged from the first compression element 11b to a high pressure in the refrigeration cycle and discharges it as gaseous refrigerant to the discharge section 11g.

[0163] Furthermore, as will be described in detail later, during refrigeration operation, a portion of the injection pipe 19 becomes low pressure. Therefore, the check valve of the second suction section 11f restricts the flow of intermediate-pressure refrigerant from the inside of the housing 11a to the outside.

[0164] The high-pressure gaseous refrigerant flowing out from the discharge section 11g passes through the switching mechanism 12 in the order of the first port P1 and the fourth port P4, and flows into the refrigerant flow path of the first heat exchanger 13 from the second end 13ab. The refrigerant flowing into the first heat exchanger 13 exchanges heat with the outdoor air at the installation location of the first heat exchanger 13, dissipating heat and becoming a high-pressure liquid refrigerant, which flows out from the first end 13aa. In this way, the first heat exchanger 13 functions as a radiator.

[0165] The high-pressure refrigerant flowing from the first heat exchanger 13 flows through the liquid pipe 16 and is depressurized to a low pressure when passing through the first expansion mechanism 14, thus becoming a gas-liquid two-phase state. Since the branch pipe 18 is equipped with a third valve 24, the refrigerant flowing through the liquid pipe 16 does not flow into the branch pipe 18, but instead passes through the fourth valve 25.

[0166] Since the first valve 22 is closed, the refrigerant passing through the fourth valve 25 does not flow into the branch pipe 18 and the injection pipe 19, but instead flows from the second end 15ab into the refrigerant flow path of the second heat exchanger 15. The refrigerant flowing into the second heat exchanger 15 exchanges heat with the water flowing in the water flow path 15b and evaporates, becoming a low-pressure gaseous refrigerant that flows out from the first end 15aa. Thus, the second heat exchanger 15 functions as an evaporator.

[0167] The low-pressure refrigerant flowing from the second heat exchanger 15 passes through the switching mechanism 12 in the order of the second port P2 and the third port P3, and flows into the first heat transfer tube 17a of the gas-liquid heat exchanger 17. As described later, during refrigeration operation, the refrigerant in the second heat transfer tube 17b is recovered to the compressor 11. Therefore, the refrigerant flowing into the first heat transfer tube 17a flows out of the first heat transfer tube 17a without heat exchange. The refrigerant flowing out of the first heat transfer tube 17a passes through the storage tank 26 and is drawn back into the compressor 11 from the first suction section 11e.

[0168] During refrigeration operation, since the first valve 22 is closed, the refrigerant flowing through the liquid pipe 16 does not flow into the injection pipe 19. Furthermore, during refrigeration operation, since the first valve 22 is closed, the second valve 23 is open, and the second expansion mechanism 20 is fully open, a portion of the injection pipe 19, the first heat transfer pipe 21a and the second heat transfer pipe 21b of the energy-saving heat exchanger 21, the second heat transfer pipe 17b of the gas-liquid heat exchanger 17, and a portion of the branch pipe 18 become low-pressure areas due to the operation of the compressor 11. Specifically, the portion of the injection pipe 19 is the section between the first valve 22 and the first suction section 11e of the compressor 11. Additionally, a portion of the branch pipe 18 is the section between the first valve 22 and the third valve 24.

[0169] As a result, when switching from heating operation to cooling operation, the refrigerant remaining in a portion of the injection pipe 19, the first heat transfer pipe 21a and the second heat transfer pipe 21b of the energy-saving heat exchanger 21, the second heat transfer pipe 17b of the gas-liquid heat exchanger 17, and a portion of the branch pipe 18 flows into the compressor 11 via the first suction section 11e and is recovered.

[0170] Thus, the gas-liquid heat exchanger 17 is configured such that refrigerant does not flow through the second heat transfer tube 17b during refrigeration operation. Furthermore, the energy-saving heat exchanger 21 is configured such that refrigerant does not flow through it during refrigeration operation.

[0171] (3-1-2) Water circuit

[0172] When pump 31 starts to operate, water filling water circuit 30 is drawn in from the suction part of pump 31 and then discharged from the discharge part of pump 31.

[0173] Water flowing out of pump 31 flows into water flow path 15b of the second heat exchanger 15. The water flowing into water flow path 15b exchanges heat with the low-pressure refrigerant flowing in refrigerant flow path 15a (is cooled) and then flows out.

[0174] Water flowing out of the second heat exchanger 15 flows into the gas-liquid separator 32. In the gas-liquid separator 32, refrigerant is recovered when it leaks into the water side in the second heat exchanger 15.

[0175] The water flowing out of the gas-liquid separator 32 is not heated by the heat source 34 and flows into the third heat exchanger 33. The water flowing into the third heat exchanger 33 exchanges heat with the indoor air in the area where the third heat exchanger 33 is located. As a result, the air in the air-conditioned space is cooled.

[0176] The water that has exchanged heat with the air at the location of the third heat exchanger 33 is drawn back into the pump 31.

[0177] (3-2) Heating Operation

[0178] The following is for reference Figure 4 The operation of the refrigeration circulation unit 1 during heating is explained. Figure 4 The heating operation shown is carried out by the control unit 4, which receives the heating operation command, to control the operation of the compressor 11, switching mechanism 12, first expansion mechanism 14, second expansion mechanism 20, first fan 13a, first valve 22, second valve 23, pump 31, second fan 33a, heat source 34, etc.

[0179] Specifically, the control unit 4 starts the compressor 11 and controls the speed of the drive motor 11d of the compressor 11. The switching mechanism 12 is controlled to a first state. The opening degree of the first expansion mechanism 14 is controlled. The control unit 4 sets the target subcooling degree of the refrigerant flowing out of the second end 15ab of the second heat exchanger 15, for example, based on the target outlet temperature of the water flowing out of the water flow path 15b of the second heat exchanger 15. Then, the control unit 4 controls the opening degree of the first expansion mechanism 14 so that the subcooling degree of the refrigerant flowing out of the second heat exchanger 15 is close to the target subcooling degree. The control unit 4 controls the opening degree of the second expansion mechanism 20, for example, so that the superheating degree of the refrigerant flowing out of the second expansion mechanism 20 is close to the predetermined target superheating degree. The first valve 22 is controlled to be in the open state. The second valve 23 is controlled to be in the closed state.

[0180] In addition, control unit 4 starts pump 31. Heat source 34 is controlled to be inactive.

[0181] (3-2-1) Refrigerant circuit

[0182] When compressor 11 starts operating, low-pressure gaseous refrigerant in the refrigeration cycle is drawn in from the first suction section 11e, and intermediate-pressure gaseous refrigerant in the refrigeration cycle is drawn in from the second suction section 11f. First compression element 11b compresses the low-pressure refrigerant drawn in from the first suction section 11e to an intermediate pressure and discharges it to the second compression element 11c. Second compression element 11c compresses the intermediate-pressure refrigerant discharged from the first compression element 11b and the intermediate-pressure refrigerant drawn in from the second suction section 11f together to a high pressure in the refrigeration cycle, and discharges it as gaseous refrigerant to the discharge section 11g.

[0183] The high-pressure gaseous refrigerant flowing out from the discharge section 11g passes through the switching mechanism 12 in the order of the first port P1 and the second port P2, and flows into the refrigerant flow path 15a of the second heat exchanger 15 from the first end 15aa. The refrigerant flowing into the second heat exchanger 15 exchanges heat with the water flowing in the water flow path 15b, dissipating heat and becoming a high-pressure liquid refrigerant, which flows out from the second end 15ab. In other words, the second heat exchanger 15 functions as a radiator.

[0184] The high-pressure refrigerant flowing from the second heat exchanger 15 flows through the liquid pipe 16. Since the first valve 22 is open and a fourth valve 25 is located downstream of the first branch 18a, the refrigerant flowing through the liquid pipe 16 does not flow through the fourth valve 25, but instead flows into the injection pipe 19 at the first branch 18a. The refrigerant flowing into the injection pipe 19, after passing through the first valve 22 in the first part 19a, is then diverted to the second part 19b of the injection pipe 19 and the branch pipe 18.

[0185] The refrigerant flowing into the second part 19b of the injection pipe 19 is depressurized to intermediate pressure as it flows through the second expansion mechanism 20. The intermediate-pressure refrigerant flows into the first heat transfer tube 21a of the energy-saving heat exchanger 21, where it exchanges heat with the refrigerant passing through the second heat transfer tube 21b of the energy-saving heat exchanger 21 and flows out from the first heat transfer tube 21a.

[0186] Because the second valve 23 is closed, the refrigerant flowing out of the first heat transfer pipe 21a does not flow into the third section 19c of the injection pipe 19, but flows into the fourth section 19d of the injection pipe 19. The refrigerant flowing into the fourth section 19d is then drawn into the compressor 11 again from the second suction section 11f.

[0187] The refrigerant flowing into the branch pipe 18 flows into the second heat transfer pipe 21b of the energy-saving heat exchanger 21, where it exchanges heat with the refrigerant that has passed through the first heat transfer pipe 21a of the energy-saving heat exchanger 21 and flows out from the second heat transfer pipe 21b.

[0188] The refrigerant flowing out of the second heat transfer tube 21b passes through the branch pipe 18 and flows into the second heat transfer tube 17b of the gas-liquid heat exchanger 17. The refrigerant flowing into the second heat transfer tube 17b exchanges heat with the refrigerant passing through the first heat transfer tube 17a of the gas-liquid heat exchanger 17, and flows into the liquid tube 16 from the second branch 18b through the third valve 24.

[0189] The refrigerant flowing into the liquid pipe 16 is depressurized to a low pressure when passing through the first expansion mechanism 14, becoming a gas-liquid two-phase refrigerant and flowing into the first heat exchanger 13 from the first end 13aa. The refrigerant flowing into the first heat exchanger 13 exchanges heat with the outdoor air where the first heat exchanger 13 is located and evaporates, becoming a low-pressure gaseous refrigerant and flowing out from the second end 13ab. In other words, the first heat exchanger 13 functions as an evaporator.

[0190] The low-pressure refrigerant flowing from the first heat exchanger 13 passes through the switching mechanism 12 in the order of the fourth port P4 and the third port P3, and flows into the first heat transfer tube 17a of the gas-liquid heat exchanger 17. The refrigerant flowing into the first heat transfer tube 17a exchanges heat with the refrigerant passing through the second heat transfer tube 17b of the gas-liquid heat exchanger 17 and then flows out of the first heat transfer tube 17a. The refrigerant flowing out of the first heat transfer tube 17a passes through the storage tank 26 and is drawn back into the compressor 11 from the first suction section 11e.

[0191] Thus, the gas-liquid heat exchanger 17 and the energy-saving heat exchanger 21 are configured to supply refrigerant flow during heating operation.

[0192] (3-2-2) Water circuit

[0193] When pump 31 starts to operate, water filling water circuit 30 is drawn in from the suction part of pump 31 and then discharged from the discharge part of pump 31.

[0194] Water flowing out of pump 31 flows into water flow path 15b of the second heat exchanger 15. The water flowing into water flow path 15b exchanges heat with the low-pressure refrigerant flowing in refrigerant flow path 15a (is heated) and then flows out.

[0195] Water flowing out of the second heat exchanger 15 flows into the gas-liquid separator 32. In the gas-liquid separator 32, refrigerant is recovered when it leaks into the water side in the second heat exchanger 15.

[0196] The water flowing out of the gas-liquid separator 32 is not heated by the heat source 34 and flows into the third heat exchanger 33. The water flowing into the third heat exchanger 33 exchanges heat with the indoor air in the area where the third heat exchanger 33 is located. As a result, the air in the air-conditioned space is heated.

[0197] The water that has exchanged heat with the air at the location of the third heat exchanger 33 is drawn back into the pump 31.

[0198] (3-3) Defrosting operation

[0199] In the refrigeration cycle unit 1, during heating operation, defrosting operation is performed when the indicators related to frosting meet the first condition. The following refers to... Figure 2 as well as Figure 5 The operation of the refrigeration circulation unit 1 during defrosting is explained.

[0200] like Figure 5 As shown, the control unit 4 determines whether the indicators related to the frosting of the first heat exchanger 13 meet the first condition (step S1). Here, the control unit 4 acquires the outside air temperature detected by the outdoor temperature sensor 41 and compares the acquired outside air temperature with the first condition.

[0201] In step S1, when the control unit 4 determines that the first condition is not met, the heating operation continues (step S2). On the other hand, in step S1, when the control unit 4 determines that the first condition is met, it determines that the first heat exchanger 13 is frosted and starts defrosting operation (step S3).

[0202] In step S3, the control unit 4 switches the switching mechanism 12 to the second state, so that the flow of refrigerant in the refrigerant circuit 10 is synchronized with the flow of refrigerant in the refrigerant circuit 10. Figure 3 The refrigerant flow is the same during the refrigeration operation shown. Furthermore, the control unit 4 stops the first fan 13a.

[0203] Specifically, in the refrigerant circuit 10, the low-pressure gaseous refrigerant in the refrigeration cycle is compressed to high pressure by the compressor 11, and then flows into the first heat exchanger 13 after passing through the switching mechanism 12. The high-pressure refrigerant flowing into the first heat exchanger 13 supplies heat to the first heat exchanger 13. As a result, the frost adhering to the first heat exchanger 13 melts, and the first heat exchanger 13 is defrosted.

[0204] The high-pressure refrigerant flowing out of the first heat exchanger 13 passes through the first expansion mechanism 14 and becomes a low-pressure gas-liquid two-phase refrigerant, which then flows into the refrigerant flow path 15a of the second heat exchanger 15. The low-pressure refrigerant flowing into the refrigerant flow path 15a exchanges heat with the water flowing in the water flow path 15b, becoming a low-pressure gaseous refrigerant, which then flows out of the second heat exchanger 15. The low-pressure gaseous refrigerant flowing out of the second heat exchanger 15 passes through the switching mechanism 12 and is drawn back into the compressor 11.

[0205] In the water circuit 30, the water flowing into the water flow path 15b of the second heat exchanger 15 exchanges heat with the low-pressure refrigerant flowing in the refrigerant flow path 15a and then flows out. Thus, the water in the water flow path 15b is cooled. Therefore, a maximum duration is set as an upper limit for the defrosting operation. For this purpose, the control unit 4 determines whether the defrosting operation has reached the maximum duration (step S4).

[0206] In step S4, when the control unit 4 determines that the predetermined time has elapsed, it ends the defrosting operation (step S5) and restarts the heating operation (step S2). In this case, the control unit 4 switches the switching mechanism 12 to the first state.

[0207] On the other hand, in step S4, if the control unit 4 determines that the maximum duration has not been reached, the defrosting operation continues. Alternatively, if the control unit 4 determines that the frost on the first heat exchanger 13 has melted before the maximum duration is reached, it can also end the defrosting operation and restart the heating operation (step S2).

[0208] (3-4) Reduced operational capacity

[0209] In the refrigeration cycle unit 1, during heating operation, if the indicators related to frosting meet the second condition, a capacity reduction operation is performed. The following refers to... Figure 6 The operation of the refrigeration cycle unit 1 when its capacity is reduced will be explained.

[0210] First, such as Figure 6 As shown, similar to the operation of the defrosting cycle, the control unit 4 determines whether the indicators related to defrosting meet the first condition (step S1). If the first condition is met, the defrosting operation begins (step S3).

[0211] Next, the control unit 4 determines whether the indicators related to frost formation meet the second condition (step S11). Here, the control unit 4 acquires the outside air temperature detected by the outdoor temperature sensor 41 and compares the acquired outside air temperature with the second condition.

[0212] In step S11, when the control unit 4 determines that the second condition is not met, the heating operation continues (step S2).

[0213] On the other hand, in step S11, when the control unit 4 determines that the second condition is met, since the first heat exchanger 13 is about to frost, it starts the capacity reduction operation (step S12). In this step S3, the flow of refrigerant in the refrigerant circuit 10 is maintained to be the same as the flow of refrigerant during heating operation.

[0214] In step S12, the capacity of the refrigeration cycle unit 1 is reduced. Here, the control unit 4 reduces the capacity of the compressor 11 or lowers the target outlet water temperature. This suppresses the temperature drop of the first heat exchanger 13.

[0215] Furthermore, in step S12, the control unit 4 activates the heat source 34 to heat the water in the water circuit 30. In this state, the control unit 4 determines whether the amount of water heated by the refrigeration circulation device 1 is greater than the amount of water heated by the heat source 34 (step S13).

[0216] In step S13, when the control unit 4 determines that the amount of water heated by the refrigeration cycle device 1 is less than the amount of water heated by the heat source 34, it switches to defrosting operation (step S3). On the other hand, in step S13, when the control unit 4 determines that the amount of water heated by the refrigeration cycle device 1 is greater than the amount of water heated by the heat source 34, it continues to perform capacity reduction operation (step S14).

[0217] Then, during reduced capacity operation, the system returns to step S1 at a predetermined time to determine whether the first condition described above is met. Therefore, when the first condition is met during reduced capacity operation (step S1), the control unit 4 switches to defrost operation. Furthermore, when the first and second conditions are no longer met during reduced capacity operation, the control unit 4 restarts heating operation (step S2).

[0218] Thus, in the refrigeration cycle device 1 of this embodiment, there are cases where the capacity reduction operation is followed by a switch to defrost operation, and cases where defrost operation is performed without capacity reduction operation.

[0219] (4) Characteristics

[0220] (4-1)

[0221] The refrigeration cycle device 1 of this embodiment includes a refrigerant circuit 10 and a control unit 4. The refrigerant circuit 10 has a first heat exchanger 13. The first heat exchanger 13 performs heat exchange between outdoor air and refrigerant. The refrigerant circuit 10 circulates refrigerant. The control unit 4 performs defrosting operation and capacity reduction operation. The defrosting operation is an operation that melts the frost adhering to the first heat exchanger 13. The capacity reduction operation is an operation that reduces capacity. The control unit performs capacity reduction operation when a second condition related to frost formation is met, and during capacity reduction operation, it performs defrosting operation when a first condition related to frost formation is met.

[0222] According to the refrigeration circulation device 1 of this embodiment, before the defrosting operation to melt the frost adhering to the first heat exchanger 13 that exchanges heat with the outside air, a capacity reduction operation is performed to reduce the capacity of the refrigeration circulation device 1 if a second condition related to frost formation is met. In other words, capacity reduction operation is performed when the second condition that the first heat exchanger 13 is about to frost is met. By performing this capacity reduction operation, frost formation on the first heat exchanger 13 can be suppressed. Therefore, the refrigeration circulation device 1 can reduce the frequency of defrosting operation, thereby improving comfort.

[0223] (4-2)

[0224] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the refrigerant includes R290.

[0225] Because R290 is a low-pressure refrigerant, the size of the first heat exchanger 13 is increased, resulting in longer defrosting operation time. However, in the refrigeration cycle apparatus 1 of this embodiment, even when using a refrigerant containing R290, frosting of the first heat exchanger 13 can be suppressed by performing reduced-capacity operation. Therefore, even when using a refrigerant containing R290, frosting of the first heat exchanger 13 can be suppressed by performing reduced-capacity operation, thus reducing the frequency of defrosting operation. Therefore, the efficiency of the refrigeration cycle apparatus 1 using a refrigerant containing R290 can be improved.

[0226] (4-3)

[0227] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the first heat exchanger 13 is a microchannel heat exchanger.

[0228] Microchannel heat exchangers are more prone to frosting compared to plate heat exchangers. However, in the refrigeration cycle apparatus 1 of this embodiment, even when such a microchannel heat exchanger is used in the first heat exchanger 13 that exchanges heat with the outside air, frosting of the first heat exchanger 13 can be suppressed by operating it with reduced capacity. Therefore, the refrigeration cycle apparatus 1 of this embodiment can suitably use a microchannel heat exchanger as the first heat exchanger 13.

[0229] (4-4)

[0230] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the refrigerant circuit 10 further includes a second heat exchanger 15. The second heat exchanger 15 performs heat exchange between the refrigerant and water. The refrigeration cycle apparatus 1 also includes a water circuit 30 and a heat source 34. The water circuit 30 supplies water flowing through the second heat exchanger 15 for circulation. The heat source 34 heats the water.

[0231] Here, when the water temperature in the water circuit 30 is lower than the target outlet temperature due to reduced heating of water by the refrigerant during reduced operation, the heat source 34 can heat the water. Therefore, it is possible to suppress the drop in water temperature while suppressing frost formation.

[0232] (4-5)

[0233] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the refrigerant circuit 10 also includes a compressor 11. The control unit 4 performs capacity reduction operation by reducing the capacity of the compressor 11 or reducing the target outlet water temperature.

[0234] Here, the capacity of the refrigeration cycle unit 1 is reduced by decreasing the capacity of the compressor 11 or by lowering the target outlet water temperature. Therefore, it is easy to achieve a refrigeration cycle unit 1 that suppresses frost formation.

[0235] (4-6)

[0236] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the control unit 4 activates the heat source 34 when the capacity is reduced.

[0237] Here, even when operating with reduced capacity, if the temperature of the water heated by the refrigerant in the second heat exchanger 15 is lower than the target outlet water temperature due to the reduced capacity of the refrigeration cycle unit 1, the heat source 34 will still heat the water. Thus, the insufficient capacity during reduced capacity operation is compensated for by the heat source 34. Therefore, the refrigeration cycle unit 1 can be easily implemented to suppress both frost formation and water temperature drop.

[0238] (4-7)

[0239] In the refrigeration cycle device 1 of this embodiment, it is preferable that when the capacity is reduced during operation, the amount of water heated by the refrigeration cycle device 1 is greater than the amount of water heated by the heat source.

[0240] Here, when the capacity is reduced during operation, the amount of water heated by the heat source 34 will not exceed the amount of water heated by the refrigeration cycle device 1, thus suppressing the reduction in the efficiency of the refrigeration cycle device 1.

[0241] (4-8)

[0242] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the second condition is that the outside air temperature is above -10°C and below 7°C.

[0243] Here, the outdoor air temperature is used as a secondary condition for control, thus making it easy to control the reduced capacity operation.

[0244] (4-9)

[0245] In the refrigeration cycle apparatus 1 of this embodiment, it is preferable that the maximum duration of defrosting operation is shorter than the maximum duration of capacity reduction operation.

[0246] Here, by continuously reducing capacity, the frequency of defrosting operation is reduced, and even when defrosting operation occurs, its maximum duration is shortened. Therefore, the time of reduced comfort due to defrosting operation can be reduced.

[0247] (4-10)

[0248] In the refrigeration cycle device 1 of this embodiment, it is preferable that when the first condition is met during reduced capacity operation, the control unit 4 switches to defrost operation.

[0249] Here, even when operating at reduced capacity, the control unit 4 will still perform defrosting operation if the first condition is met. As a result, the efficiency reduction of the refrigeration cycle unit 1 can be suppressed.

[0250] (5) Variations

[0251] (5-1) Variation Example 1

[0252] (5-1-1) Summary

[0253] In the above embodiment, the control unit 4 activates the heat source only during capacity reduction operation, but is not limited to this. In this modified example, the control unit 4 activates the heat source 34 during defrosting operation and during capacity reduction operation. Specifically, the control unit 4 may activate the heat source 34 at the start of defrosting operation or after a predetermined time has elapsed since the start of defrosting operation.

[0254] (5-1-2) Features

[0255] Thus, in the refrigeration cycle device 1 of this modified example, the control unit 4 activates the heat source 34 during defrosting operation. Here, even if the water temperature decreases during defrosting operation, the heat source 34 can heat the water to suppress the decrease in comfort.

[0256] (5-2) Variation Example 2

[0257] In the above embodiment, the heat source 34 is a heater that can be selectively started and stopped, but it is not limited to this. In this variation, the output of the heat source 34 is variable. Specifically, the heat source 34 is a heater capable of providing two or more levels of output.

[0258] Furthermore, the control unit 4 controls the output of the heat source 34 during capacity reduction operation to be greater than that during defrost operation. Moreover, when the amount of water heated by the heat source 34 exceeds the amount of water heated by the refrigeration cycle unit 1, the control unit 4 can switch from capacity reduction operation to defrost operation regardless of the first condition.

[0259] (5-3) Variation Example 3

[0260] In the above embodiment, the water circuit 30 has a heat source 34, but the heat source 34 may not constitute the water circuit 30. In this case, the heat source 34 may be provided in the utilization unit 3 or in the heat source unit 2.

[0261] Furthermore, the heat source 34 included in the refrigeration cycle unit 1 is not limited to one, but can also be multiple. In this case, multiple heat sources 34 can be respectively configured in the utilization unit 3 and the heat source unit 2, or they can be configured in only one of them.

[0262] (5-4) Variation Example 4

[0263] (5-4-1) Summary

[0264] In the above embodiment, the second condition is described as a predetermined external air temperature, but it is not limited to this. In this variation, the second condition is a state where the required external air temperature exceeds the ability of the first heat exchanger 13 to operate without frost. Furthermore, "the ability of the first heat exchanger 13 to operate without frost" refers to the maximum capacity of the first heat exchanger 13 to perform heating operation without frost. Hereinafter, refer to... Figure 7 Please provide an explanation.

[0265] Figure 7 An example of the relationship between the external air temperature and the capacity of the refrigeration cycle unit 1 is shown. Figure 7 In this context, line L1 represents the capacity of the refrigeration cycle unit 1 based on the required external air temperature, and line L2 represents the capacity of the refrigeration cycle unit 1 such that the first heat exchanger 13 can operate without frost formation. For example... Figure 7 As shown, the slope of line L1, which represents the capability required based on the outside air temperature, is different from the slope of line L2, which represents the capability of the first heat exchanger 13 to operate without frost.

[0266] The second condition in this variation is that the capacity of line L1 is higher than that of line L2. This condition occurs when, despite a lower external air temperature, the refrigeration cycle unit 1 is still outputting capacity, causing the first heat exchanger 13 to cool and potentially frost over. Here, the second condition is that the temperature is within a specified external air temperature range (…). Figure 7Below -3℃, and with a capacity exceeding a certain level ( Figure 7 When the power is 7kW.

[0267] Furthermore, in this modified example, the control unit 4 activates the heat source 34 to control... Figure 7 The capacity of the middle region R1 is compensated. Specifically, the control unit 4 controls the heat source 34 so that the heat source 34 can handle the difference between the capacity of line L1 and the capacity of line L2 for a specified external air temperature.

[0268] (5-4-2) Features

[0269] In the refrigeration cycle device 1 of this modified example, the second condition is based on the state where the required external air temperature exceeds the ability of the first heat exchanger 13 to operate without frost.

[0270] The condition where the required capacity for the outside air temperature exceeds the capacity to prevent frost formation is due to a condition where the outside air temperature is low and the capacity of the refrigeration cycle unit 1 is high. In this case, the first heat exchanger 13 is cooled and therefore becomes prone to frost formation. Therefore, this condition is considered to satisfy the second condition, thereby enabling effective suppression of frost formation by operating with reduced capacity.

[0271] (5-5) Variation Example 5

[0272] (5-5-1) Summary

[0273] In the above embodiment, the second condition of a predetermined external air temperature was used as an example for explanation, but it is not limited to this. In this modified example, the second condition is that the evaporation temperature of the refrigerant in the first heat exchanger 13 is at least a predetermined temperature lower than the dew point temperature, and the external air temperature is 2°C or lower. Hereinafter, refer to... Figure 8 Please provide an explanation.

[0274] Figure 8 An example is shown illustrating the relationship between the external air temperature, dew point temperature, and evaporation temperature of the refrigeration cycle unit 1. Figure 8 In the diagram, line L3 represents the dew point temperature relative to the outside air temperature under standard temperature conditions, and line L4 represents the lower limit of the evaporation temperature at which the first heat exchanger 13 can operate in heating mode without frosting. The evaporation temperature is the evaporation temperature of the refrigerant flowing out from the second end 13ab of the first heat exchanger 13. Standard temperature conditions are defined as a wet-bulb temperature that is 1°C lower than the dry-bulb temperature.

[0275] The second condition in this variation is that when the outside air temperature is below 2°C, the evaporation temperature of line L4 is more than a specified temperature lower than the dew point temperature of line L3. This state occurs because the outside air temperature is low and the evaporation temperature of the first heat exchanger 13 is low, causing the first heat exchanger 13 to cool down and thus be about to frost over. Here, the second condition is that the outside air temperature is below 2°C and the evaporation temperature is lower than the dew point temperature by a specified temperature (…). Figure 8 When the temperature is above 2℃.

[0276] Furthermore, in this modified example, the control unit 4 activates the heat source 34 to control... Figure 8 The evaporation temperature in the middle region R2 is compensated. Specifically, the control unit 4 controls the heat source 34 so that the heat source 34 bears the evaporation temperature of line L3 for the specified external air temperature. Figure 8 (The temperature is 2°C below the dew point). In other words, the control unit 4 controls the heat source 34 to keep the evaporation temperature of the first heat exchanger 13 within 2°C of the dew point.

[0277] (5-5-2) Features

[0278] Thus, in the refrigeration cycle apparatus 1 of this modified example, the second condition is that the evaporation temperature of the refrigerant in the first heat exchanger 13 is more than a specified temperature lower than the dew point temperature, and the outside air temperature is 2°C or less.

[0279] When the evaporation temperature is more than a specified temperature below the dew point temperature and the outside air temperature is as low as 2°C or less, the first heat exchanger 13 is cooled and therefore prone to frost formation. Therefore, this condition is considered to satisfy the second condition, thereby effectively suppressing frost formation by operating with reduced capacity.

[0280] (5-6) Variation Example Six

[0281] In the above embodiments, capacity reduction operation is performed by reducing the compressor capacity or lowering the target outlet water temperature, but it is not limited to this. Capacity reduction operation can also be performed during heating operation by reducing capacity through other controls or multiple controls. In this modified example, capacity reduction operation is performed by controlling the reduction of the evaporation temperature of the first heat exchanger 13.

[0282] (5-7) Variation Example 7

[0283] In the above embodiments, the refrigerant circulation in the refrigerant circuit 10 during defrosting operation is the same as that during refrigeration operation. However, it is not limited to this as long as the refrigerant flows from the compressor 11 to the first heat exchanger 13 during defrosting operation, and the first heat exchanger 13 functions as a radiator. The flow of refrigerant in the refrigerant circuit 10 during defrosting operation may also be different from that during refrigeration operation.

[0284] (5-8) Variation Example 8

[0285] In the above embodiment, a refrigeration cycle device 1 including a third heat exchanger 33 has been described as an example, but it is not limited thereto. The refrigeration cycle device 1 may also include multiple third heat exchangers 33.

[0286] In this modified example, multiple third heat exchangers 33 are connected in parallel to the second heat exchanger 15. Furthermore, there are multiple utilization units 3, including the third heat exchangers 33. These multiple utilization units 3 may or may not be able to operate independently in either cooling or heating mode.

[0287] (5-9) Variation Example Nine

[0288] In the above embodiment, in the second heat exchanger 15, the refrigerant flowing in the refrigerant circuit 10 exchanges heat with the water flowing in the water circuit 30, but this is not a limitation. In this variation, the refrigerant flowing in the refrigerant circuit 10 may also exchange heat with the air in the target space. In this case, the water circuit 30 is omitted, and the second heat exchanger 15 is disposed in the target space.

[0289] (5-10) Variation Example 10

[0290] In the above embodiment, the refrigeration cycle device 1 includes a refrigerant circuit 10 and a water circuit 30, but is not limited thereto. In this variation, the refrigeration cycle device includes a medium circuit for supplying a medium to replace the water circuit for supplying a water circuit. The medium includes a refrigerant and a heat medium. Here, carbon dioxide circulates in the medium circuit. Therefore, the carbon dioxide that has exchanged heat with the refrigerant in the second heat exchanger 15 heats or cools the air in the target space in the third heat exchanger 33.

[0291] (5-11) Variation Example Eleven

[0292] In the above embodiments, a flammable refrigerant is used as the refrigerant, but the method is not limited to this. In this modified example, a low-pressure refrigerant with a pressure exceeding 0.08 MPa and below 0.8 MPa at a condensation temperature of 25°C is used as the refrigerant.

[0293] The embodiments of this disclosure have been described above. However, it should be understood that various changes in form and detail can be made without departing from the spirit and scope of this disclosure as set forth in the claims.

[0294] Symbol Explanation

[0295] 1. Refrigeration circulation unit; 4. Control Unit; 10. Refrigerant circuit; 11. Compressor; 13. First heat exchanger; 15. Second heat exchanger; 30. Water circuit; 31. Pump; 32. Gas-liquid separator; 33. Third heat exchanger; 33a Second fan; 34. Heat source.

[0296] Existing technical documents

[0297] Patent documents

[0298] Patent Document 1: Japanese Patent Application Publication No. 2018-91579

Claims

1. A refrigeration circulation device (1), characterized in that, include: A refrigerant circuit (10) having a first heat exchanger (13) for heat exchange between outdoor air and refrigerant, and for circulating the refrigerant; as well as The control unit (4) performs defrosting operation to melt the frost adhering to the first heat exchanger and capacity reduction operation. The control unit performs the capacity reduction operation when the frost-related indicators meet the second condition, and performs the defrosting operation when the frost-related indicators meet the first condition during the capacity reduction operation.

2. The refrigeration cycle apparatus according to claim 1, characterized in that, The refrigerant contains R290.

3. The refrigeration cycle apparatus according to claim 1 or 2, characterized in that, The first heat exchanger is a microchannel heat exchanger.

4. The refrigeration cycle apparatus according to any one of claims 1 to 3, characterized in that, The refrigerant circuit also has a second heat exchanger (15) for heat exchange between the refrigerant and water. The refrigeration cycle device also includes: Water circuit (30), the water circuit supplying the water circulation flowing in the second heat exchanger; and A heat source (34) heats the water.

5. The refrigeration cycle apparatus according to claim 4, characterized in that, The refrigerant circuit also includes a compressor (11). The control unit reduces the capacity by decreasing the capacity of the compressor or by lowering the target outlet temperature of the water.

6. The refrigeration cycle apparatus according to claim 4 or 5, characterized in that, The control unit activates the heat source when the capacity is reduced.

7. The refrigeration cycle apparatus according to claim 6, characterized in that, When the capacity is reduced, the amount of water heated by the refrigeration circulation device is greater than the amount of water heated by the heat source.

8. The refrigeration cycle apparatus according to any one of claims 4 to 7, characterized in that, The control unit activates the heat source during the defrosting operation.

9. The refrigeration cycle apparatus according to any one of claims 1 to 8, characterized in that, The second condition is that the outside air temperature is above -10°C and below 7°C.

10. The refrigeration cycle apparatus according to any one of claims 1 to 8, characterized in that, The second condition is based on the condition that the required external air temperature exceeds the ability to operate the first heat exchanger without frost formation.

11. The refrigeration cycle apparatus according to any one of claims 1 to 8, characterized in that, The second condition is that the evaporation temperature of the refrigerant in the first heat exchanger is more than a specified temperature lower than the dew point temperature, and the outside air temperature is below 2°C.

12. The refrigeration cycle apparatus according to any one of claims 1 to 11, characterized in that, The maximum duration of the defrosting operation is shorter than the maximum duration of the capacity reduction operation.

13. The refrigeration cycle apparatus according to any one of claims 1 to 12, characterized in that, When the first condition is met during reduced capacity operation, the control unit switches to defrosting operation.

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