EP3246637B1 - Refrigeration cycle device - Google Patents
Refrigeration cycle device Download PDFInfo
- Publication number
- EP3246637B1 EP3246637B1 EP15877851.4A EP15877851A EP3246637B1 EP 3246637 B1 EP3246637 B1 EP 3246637B1 EP 15877851 A EP15877851 A EP 15877851A EP 3246637 B1 EP3246637 B1 EP 3246637B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- refrigerant
- compressor
- suction
- flow
- bypass
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000005057 refrigeration Methods 0.000 title claims description 112
- 239000003507 refrigerant Substances 0.000 claims description 332
- 230000002265 prevention Effects 0.000 claims description 98
- 230000001105 regulatory effect Effects 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 6
- 230000001276 controlling effect Effects 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 52
- 238000012986 modification Methods 0.000 description 36
- 230000004048 modification Effects 0.000 description 36
- 239000007788 liquid Substances 0.000 description 35
- 238000010586 diagram Methods 0.000 description 33
- FXRLMCRCYDHQFW-UHFFFAOYSA-N 2,3,3,3-tetrafluoropropene Chemical compound FC(=C)C(F)(F)F FXRLMCRCYDHQFW-UHFFFAOYSA-N 0.000 description 12
- 238000001704 evaporation Methods 0.000 description 11
- 238000012546 transfer Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 230000008020 evaporation Effects 0.000 description 10
- CDOOAUSHHFGWSA-OWOJBTEDSA-N (e)-1,3,3,3-tetrafluoroprop-1-ene Chemical compound F\C=C\C(F)(F)F CDOOAUSHHFGWSA-OWOJBTEDSA-N 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 238000013459 approach Methods 0.000 description 8
- 229920006395 saturated elastomer Polymers 0.000 description 6
- 238000010257 thawing Methods 0.000 description 6
- 230000007257 malfunction Effects 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 238000010792 warming Methods 0.000 description 2
- RBIIKVXVYVANCQ-CUWPLCDZSA-N (2s,4s,5s)-5-amino-n-(3-amino-2,2-dimethyl-3-oxopropyl)-6-[4-(2-chlorophenyl)-2,2-dimethyl-5-oxopiperazin-1-yl]-4-hydroxy-2-propan-2-ylhexanamide Chemical compound C1C(C)(C)N(C[C@H](N)[C@@H](O)C[C@@H](C(C)C)C(=O)NCC(C)(C)C(N)=O)CC(=O)N1C1=CC=CC=C1Cl RBIIKVXVYVANCQ-CUWPLCDZSA-N 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B13/00—Compression machines, plants or systems, with reversible cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
- F25B47/022—Defrosting cycles hot gas defrosting
- F25B47/025—Defrosting cycles hot gas defrosting by reversing the cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2339/00—Details of evaporators; Details of condensers
- F25B2339/04—Details of condensers
- F25B2339/047—Water-cooled condensers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2341/00—Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
- F25B2341/001—Ejectors not being used as compression device
- F25B2341/0011—Ejectors with the cooled primary flow at reduced or low pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/04—Refrigeration circuit bypassing means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/04—Refrigeration circuit bypassing means
- F25B2400/0403—Refrigeration circuit bypassing means for the condenser
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/04—Refrigeration circuit bypassing means
- F25B2400/0409—Refrigeration circuit bypassing means for the evaporator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/19—Calculation of parameters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2600/00—Control issues
- F25B2600/02—Compressor control
- F25B2600/027—Compressor control by controlling pressure
- F25B2600/0272—Compressor control by controlling pressure the suction pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2501—Bypass valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
- F25B2700/193—Pressures of the compressor
- F25B2700/1933—Suction pressures
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2115—Temperatures of a compressor or the drive means therefor
- F25B2700/21151—Temperatures of a compressor or the drive means therefor at the suction side of the compressor
Definitions
- the present invention relates to a refrigeration cycle apparatus for a heat pump water heater or other apparatuses.
- US 2011/132006 A1 describes a refrigeration cycle apparatus using a compressor discharge bypass and a suction bypass combining the flow of the compressor discharge bypass with a refrigerant flow downstream the condenser and routing the combined flow to the suction side of the compressor. Furthermore, a negative pressure prevention valve is controlled such that negative compressor suction pressure is avoided.
- Patent Literature 1 Japanese Unexamined Patent Application Publication No. 2011-252638
- HFO-1234yf used in the technique disclosed in Patent Literature 1 is refrigerant having a higher boiling point than refrigerant, such as R407C and R410A, having been used. For this reason, the refrigerant has the property that a compressor suction pressure decreases. Thus, when a heating operation is performed under low outdoor air temperature conditions in particular, the operation is performed in a negative pressure state in which a compressor suction pressure is lower than an atmospheric pressure, thereby causing the problem of the occurrence of a disadvantage, such as a malfunction due to suction of air.
- the present invention has been made to solve a problem like that described above and provides a refrigeration cycle apparatus that, even when refrigerant having a higher boiling point than R407C refrigerant is used, can prevent a compressor suction pressure from falling to or below an atmospheric pressure under low outdoor air temperature conditions and increase reliability.
- a refrigeration cycle apparatus can be obtained that, even when refrigerant having a higher boiling point than R407C refrigerant is used, can prevent a compressor suction pressure from falling to or below an atmospheric pressure under low outdoor air temperature conditions and increase reliability.
- Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention and illustrates a state provided while a heating operation (hot-water supply operation) of raising the temperature of water on a load side is being performed.
- a heating operation hot-water supply operation
- the refrigeration cycle apparatus includes a main circuit 30 in which a compressor 1, a four-way valve 2, a condenser 3, a main expansion valve 4, and an evaporator 5 are connected in a circle, and through which refrigerant circulates, a bypass 40, and a discharged gas bypass valve 7 serving as a negative pressure regulating valve that regulates a flow rate in the bypass 40.
- the compressor 1 is constituted by, for example, an inverter compressor capable of controlling capacity, sucks low-temperature low-pressure gas refrigerant, compresses the refrigerant to turn it into a high-temperature high-pressure gas refrigerant state, and discharges thereof.
- the four-way valve 2 switches a direction in which the high-temperature high-pressure gas refrigerant discharged from the compressor 1 flows to the direction of the condenser 3 or the evaporator 5.
- the condenser 3 is constituted by a plate-type heat exchanger and exchanges heat between refrigerant flowing through the main circuit 30 and a medium to be subjected to heat exchange supplied from a cooling load (not illustrated) to transfer heat.
- the main expansion valve 4 reduces the pressure of high-pressure refrigerant to turn the refrigerant into low-pressure two-phase refrigerant.
- the evaporator 5 is constituted by, for example, a plate-fin-type heat exchanger and exchanges heat between refrigerant and air to evaporate the refrigerant.
- the bypass 40 includes a discharged gas bypass 6 and a suction bypass 8, and is a circuit that combines a flow of part of refrigerant discharged from the compressor 1 and a flow of refrigerant having flowed out of the condenser 3 into a combined flow to allow the combined flow to flow into a suction side of the compressor 1.
- the discharged gas bypass 6 bypasses part of discharged refrigerant discharged from the compressor 1 to the suction side of the compressor 1.
- the discharged gas bypass valve 7 is provided in the discharged gas bypass 6 and regulates a bypass flow rate of discharged gas to be passed through the discharged gas bypass 6.
- An increase in the opening degree of the discharged gas bypass valve 7 increases a flow rate of refrigerant passing through the discharged gas bypass 6 and returning to the suction side of the compressor 1 and increases a compressor suction pressure.
- a reduction in the opening degree of the discharged gas bypass valve 7 reduces a flow rate of refrigerant passing through the discharged gas bypass 6 and returning to the suction side of the compressor 1 and reduces a compressor suction pressure.
- the suction bypass 8 combines a flow of high-pressure refrigerant at an outlet of the condenser 3 into a flow in the discharged gas bypass 6 to allow the flow to flow into the suction side of the compressor 1.
- a suction bypass valve 9 is provided in the suction bypass 8 and regulates a flow rate of refrigerant to be passed through the suction bypass 8.
- An increase in the opening degree of the suction bypass valve 9 increases a flow rate of high-pressure refrigerant passing through the suction bypass 8 and flowing into the suction side of the compressor 1 and thus reduces a compressor suction superheat degree.
- a reduction in the opening degree of the suction bypass valve 9 reduces a flow rate of high-pressure refrigerant flowing from the suction bypass 8 into the suction side of the compressor 1 and thus increases a compressor suction superheat degree.
- refrigerant containing HFO-1234yf refrigerant or HFO-1234ze refrigerant is used as refrigerant.
- Refrigerant may be a single refrigerant of HFO-1234yf, a single refrigerant of HFO-1234ze, or a refrigerant mixture containing HFO-1234yf or HFO-1234ze.
- R32 can be used, for example.
- a global warming potential (GWP) of the HFO-1234yf refrigerant or the HFO-1234ze refrigerant is "4", which is lower than "2090" of existing R410A refrigerant and "1770" of R407C refrigerant, and thus the HFO-1234yf refrigerant or the HFO-1234ze refrigerant is refrigerant that has less impact on the global environment.
- the discharged gas bypass valve 7 and the suction bypass valve 9 are fully closed, and refrigerant does not flow through the discharged gas bypass 6 and the suction bypass 8.
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure refrigerant discharged from the compressor 1 flows into the condenser 3 via the four-way valve 2.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- the high-pressure liquid refrigerant having flowed out of the condenser 3 flows into the main expansion valve 4 and is reduced in pressure and expanded to turn into low-temperature low-pressure two-phase gas-liquid refrigerant.
- the two-phase gas-liquid refrigerant having flowed out of the main expansion valve 4 flows into the evaporator 5, cools air serving as a medium to be subjected to heat exchange, and evaporates to turn into low-temperature low-pressure gas refrigerant.
- the low-temperature low-pressure gas refrigerant having flowed out of the evaporator 5 passes through the four-way valve 2 again and then is sucked into the compressor 1 again.
- Fig. 2 is a graph illustrating comparisons of relationships between saturation temperatures and saturated vapor pressures of various types of refrigerant.
- refrigerant R410A refrigerant, R407C refrigerant, HFO-1234yf refrigerant, and HFO-1234ze are illustrated.
- the horizontal axis represents saturation temperature [DEGREES C]
- the vertical axis represents saturated vapor pressure [MPa (abs)].
- the HFO-1234yf refrigerant used in Embodiment 1 is lower than the R410A refrigerant and R407C refrigerant that have been used.
- an evaporating temperature may fall below a saturated vapor temperature of -29.5 degrees C at an atmospheric pressure, resulting in a negative pressure operation in which a compressor suction pressure is equal to or less than the atmospheric pressure.
- the compressor suction pressure becomes negative, air is sucked into the refrigeration cycle, resulting in the occurrence of a disadvantage, such as a malfunction of the refrigeration cycle.
- the refrigeration cycle apparatus performs a negative pressure prevention operation of continuing a hot-water supply operation with a compressor suction pressure being equal to or greater than a negative pressure even under low outdoor air temperature conditions.
- Fig. 3 is a P-h diagram illustrating an action state in a negative pressure prevention operation in the refrigeration cycle apparatus according to Embodiment 1 of the present invention.
- [1] to [5] respectively indicate refrigerant states at positions of [1] to [5] in Fig. 1 .
- the opening degree of the main expansion valve 4 is in a substantially-closed state.
- An opening degree being in the "substantially-closed" state refers to not only an opening degree being in a fully-closed state but also such an exceedingly small opening degree that has no adverse effect in preventing negative pressure.
- an opening degree being in the "substantially-closed” state corresponds to an opening degree being in a fully-closed state or in a state close to the fully-closed state.
- refrigerant ([1]) being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure refrigerant ([2]) discharged from the compressor 1 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the discharged gas bypass 6 and is reduced in pressure by the discharged gas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant ([3]), and it is bypassed to the suction side of the compressor 1.
- the high-pressure liquid refrigerant having flowed out of the condenser 3 flows into the suction bypass 8 and is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant ([5]).
- a flow of the high-temperature low-pressure gas ([3]) that has been reduced in pressure by the discharged gas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant ([5]) that has been reduced in pressure and expanded by the suction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant ([1]), and the flow is sucked into the compressor 1 again.
- the main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into the evaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur.
- the negative pressure prevention operation is started when an operation state in which a compressor suction pressure is close to a negative pressure is entered, and is an operation that causes little refrigerant to flow into the evaporator 5 and causes most of high-pressure refrigerant having flowed out of the condenser 3 to flow into the suction bypass 8. Then, the discharged gas bypass valve 7 is controlled so that a compressor suction pressure becomes higher than the negative pressure, thereby preventing negative pressure. In Embodiment 1, in addition to control of the discharged gas bypass valve 7, the suction bypass valve 9 is also controlled so that a compressor suction superheat degree is put into an appropriate state.
- Fig. 4 is a system configuration diagram of the refrigeration cycle apparatus according to Embodiment 1 of the present invention.
- Fig. 5 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according to Embodiment 1 of the present invention.
- the refrigeration cycle apparatus includes a controller 20, a compressor suction pressure sensor 21, and a compressor suction temperature sensor 22. Note that the other components are the same as those in Fig. 1 .
- the controller 20 controls the entire refrigeration cycle apparatus.
- the controller 20 is constituted by a microcomputer, for example, and includes a CPU, a RAM, a ROM, and other components.
- a control program and a program corresponding to the flowchart of Fig. 5 are stored.
- the compressor suction pressure sensor 21 and the compressor suction temperature sensor 22 are connected to the controller 20 so that detection signals from the respective sensors can be received. Based on, for example, these detection signals, the controller 20 controls the opening degree of the main expansion valve 4, the opening degree of the discharged gas bypass valve 7, and the opening degree of the suction bypass valve 9, for example. The controller 20 also controls, based on, for example, detection signals from the respective sensors 21 and 22, various operations including a negative pressure prevention operation.
- the controller 20 includes a negative pressure prevention control unit 20a and a superheat degree control unit 20b.
- the negative pressure prevention control unit 20a performs a negative pressure prevention operation of controlling the discharged gas bypass valve 7 to prevent a suction pressure of the compressor 1 from becoming negative.
- the superheat degree control unit 20b regulates the opening degree of the suction bypass valve 9 so that a degree of superheat of gas to be sucked into the compressor 1 becomes a setting value set in advance.
- the negative pressure prevention control unit 20a and the superheat degree control unit 20b are functionally configured by the CPU and the control program.
- the controller 20 acquires a compressor suction pressure Ps detected by the compressor suction pressure sensor 21 (S1). Then, the controller 20 compares the compressor suction pressure Ps with a setting value 1 (It is, for example, 0.01 MPa (G), which is a setting value representing at least a positive pressure.) that has been set in advance and is an upper limit pressure at which a negative pressure prevention operation is started (S2). While the compressor suction pressure Ps is equal to or greater than the setting value 1, the controller 20 returns to step S1, and a normal hot-water supply operation is continued.
- a setting value 1 It is, for example, 0.01 MPa (G), which is a setting value representing at least a positive pressure.
- the controller 20 determines that the refrigeration cycle apparatus is in an operation state in which an outdoor air temperature is low and the compressor suction pressure is close to a negative pressure, and starts the negative pressure prevention operation (S3).
- the controller 20 substantially closes the main expansion valve 4 (its opening degree is reduced to an opening degree being in a fully-closed state or in a state close to the fully-closed state) (S4).
- the controller 20 compares a setting value 2 (It is, for example, 0.02 MPa (G), which is a setting value representing at least a positive pressure.) that has been set in advance as a target value of a compressor suction pressure with the compressor suction pressure Ps (S5).
- the controller 20 increases the opening degree of the discharged gas bypass valve 7 (S6).
- the compressor suction pressure Ps rises and approaches the setting value 2.
- the opening degree of the discharged gas bypass valve 7 is reduced (S7).
- the compressor suction pressure Ps falls and approaches the setting value 2. Note that, although not illustrated in Fig. 5 , when the compressor suction pressure Ps is equal to the setting value 2, the opening degree of the discharged gas bypass valve 7 may remain unchanged.
- the controller 20 acquires a compressor suction temperature Ts detected by the compressor suction temperature sensor 22. Then, the controller 20 calculates a compressor suction superheat degree SHs by using the acquired compressor suction temperature Ts (S9). That is, the controller 20 calculates a saturation temperature f(Ps) of the compressor suction pressure Ps and subtracts the saturation temperature f(Ps) of the compressor suction pressure Ps from the compressor suction temperature Ts to get a compressor suction superheat degree SHs.
- the controller 20 compares the calculated compressor suction superheat degree SHs with a setting value 3 (for example, 5 K) that has been set in advance as a target value of a compressor suction superheat degree (S10). Then, when the compressor suction superheat degree SHs is lower than the setting value 3, the controller 20 reduces the opening degree of the suction bypass valve 9 (S11). Thus, the compressor suction superheat degree SHs rises and approaches the setting value 3. On the other hand, when the compressor suction superheat degree SHs is higher than the setting value 3, the opening degree of the suction bypass valve 9 is increased (S12). Thus, the compressor suction superheat degree SHs falls and approaches the setting value 3. Note that, although not illustrated in Fig.
- the opening degree of the suction bypass valve 9 may remain unchanged. Then, after the process of S11 or S12, the controller 20 returns to S5 and repeatedly performs control so that the compressor suction pressure Ps and the compressor suction superheat degree SHs respectively become equal to the corresponding setting value 2 and setting value 3.
- the refrigeration cycle apparatus when the refrigeration cycle apparatus according to Embodiment 1 enters an operation state in which an outdoor air temperature is low and a compressor suction pressure is close to a negative pressure, the refrigeration cycle apparatus continues a hot-water supply operation with the main expansion valve 4 being fully closed without evaporation of refrigerant in the evaporator 5. Then, the compressor suction pressure is controlled by using the opening degree of the discharged gas bypass valve 7, and a compressor suction superheat degree is also controlled by using the opening degree of the suction bypass valve 9. This prevents the compressor suction pressure from becoming negative and also enables the hot-water supply operation to continue with the compressor suction superheat degree being appropriate.
- Embodiment 2 a two-way valve is further included in the structure in Embodiment 1 illustrated in Fig. 1 . Note that the other components are the same as those in Fig. 1 . A description will be given below with emphasis on a respect in which Embodiment 2 differs from Embodiment 1.
- Fig. 6 is a system configuration diagram of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.
- Fig. 7 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according to Embodiment 2 of the present invention.
- the refrigeration cycle apparatus according to Embodiment 2 further includes a two-way valve 10 in addition to the structure in Embodiment 1.
- the two-way valve 10 is disposed between the four-way valve 2 and the evaporator 5 and interrupts the flow of refrigerant between the four-way valve 2 and the evaporator 5 by closing the two-way valve 10.
- a negative pressure prevention operation in the refrigeration cycle apparatus according to Embodiment 2 differs from that in Embodiment 1 in that a step of closing the two-way valve 10 (S21) is further included in the flowchart in Embodiment 1 illustrated in Fig. 5 , and the other steps are the same as those in Embodiment 1. It is only necessary that the step of closing the two-way valve 10 be provided between step S3 and step S5.
- the refrigeration cycle apparatus produces the same effect as that in Embodiment 1 and also produces the following effect. That is, closing the two-way valve 10 during a negative pressure prevention operation can prevent low-pressure high-temperature refrigerant (refrigerant indicated by a dotted arrow in Fig. 6 ) having flowed out of the discharged gas bypass valve 7 from flowing into the cold evaporator 5 via the four-way valve 2, condensing, and accumulating. This does not result in any lack of refrigerant circulating through the discharged gas bypass 6 and the suction bypass 8 and enables the negative pressure prevention operation to continue.
- low-pressure high-temperature refrigerant refrigerant indicated by a dotted arrow in Fig. 6
- Embodiment 3 an ejector and a suction pipe are further included in the structure in Embodiment 1 illustrated in Fig. 1 . Note that the other components are the same as those in Fig. 1 . A description will be given below with emphasis on a respect in which Embodiment 3 differs from Embodiment 1.
- Fig. 8 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 3 of the present invention.
- An ejector 11 is disposed on a downstream side of the discharged gas bypass valve 7 of the discharged gas bypass 6 and sucks refrigerant on an evaporator 5 side via a suction pipe 12.
- Fig. 9 is a schematic view of the ejector of Fig. 8 .
- the ejector 11 is constituted by three sections: a nozzle 11a, an expansion section 11b, and a diffuser 11c.
- a main flow flowing in from an inlet is throttled by the nozzle 11a and put into a state in which its flow velocity at the expansion section 11b is higher than that at the inlet.
- the pressure, flow velocity, and density of refrigerant at the inlet are respectively P1, v1, and p1
- the pressure, flow velocity, and density of refrigerant at the expansion section 11b are respectively P2, v2, and p2
- P 1 + 1 2 ⁇ 1 ⁇ 1 2 P 2 + 1 2 ⁇ 2 ⁇ 2 2 2
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure refrigerant discharged from the compressor 1 is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the discharged gas bypass 6 and is reduced in pressure by the discharged gas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it flows into the ejector 11.
- a refrigerant pressure decreases as a refrigerant flow velocity increases, and refrigerant on the evaporator 5 side is sucked via the suction pipe 12 connected to the refrigerant suction section 11d.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3 via the four-way valve 2.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- the high-pressure liquid refrigerant having flowed out of the condenser 3 flows into the suction bypass 8 and is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant.
- a flow of the high-temperature low-pressure gas that has been reduced in pressure by the discharged gas bypass valve 7 and passed through the ejector 11 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by the suction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant, and the flow is sucked into the compressor 1 again.
- the refrigeration cycle apparatus produces the same effect as that in Embodiment 1 and also produces the following effect. That is, even when low-pressure high-temperature refrigerant having flowed out of the discharged gas bypass valve 7 flows into the cold evaporator 5 via the four-way valve 2 during a negative pressure prevention operation, the refrigerant having flowed to the evaporator 5 side is sucked by the ejector 11 to enable the refrigerant to be drawn back to the discharged gas bypass 6.
- refrigerant having flowed out of the discharged gas bypass valve 7 and flowed into the evaporator 5 can be prevented from condensing and accumulating in the evaporator 5. This does not result in any lack of refrigerant circulating through the discharged gas bypass 6 and the suction bypass 8 and enables the negative pressure prevention operation to continue.
- Embodiment 4 a receiver is further included in the structure in Embodiment 1 illustrated in Fig. 1 . Note that the other components are the same as those in Fig. 1 . A description will be given below with emphasis on a respect in which Embodiment 4 differs from Embodiment 1.
- Fig. 10 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 4 of the present invention.
- a receiver 13 is disposed on a pipe connecting the condenser 3 and the suction bypass valve 9 and stores excess refrigerant caused during an operation.
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure refrigerant discharged from the compressor 1 is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the discharged gas bypass 6 and is reduced in pressure by the discharged gas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it is bypassed to the suction side of the compressor 1.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3 via the four-way valve 2.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- the high-pressure liquid refrigerant having flowed out of the condenser 3 flows into the suction bypass 8 via the receiver 13 and is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant.
- a flow of the high-temperature low-pressure gas that has been reduced in pressure by the discharged gas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by the suction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant, and the flow is sucked into the compressor 1 again.
- the refrigeration cycle apparatus produces the same effect as that in Embodiment 1 and also produces the following effect. That is, excess refrigerant can be stored in the receiver 13 during a negative pressure prevention operation, thereby preventing an operation in which liquid flows back to the suction side of the compressor 1 and enabling a highly reliable negative pressure prevention operation to continue.
- Embodiment 4 presents the structure including a refrigerant storage container (the receiver 13 herein), the disposition of the refrigerant storage container is not limited to the disposition illustrated in Fig. 10 , and modifications can be made as described in the following Modifications 1 and 2.
- Fig. 11 is a refrigerant circuit diagram of a refrigeration cycle apparatus illustrating Modification 1 of the refrigeration cycle apparatus according to Embodiment 4 of the present invention.
- a refrigerant circuit of Modification 1 of the refrigeration cycle apparatus according to Embodiment 4 includes a receiver 13a and a check valve 14 in place of the receiver 13 of Fig. 10 . Note that the other components are the same as those in Fig. 10 .
- the receiver 13a is a refrigerant storage container that stores excess refrigerant caused during an operation.
- the receiver 13a is provided in parallel with the main circuit 30 on an outlet side of the condenser 3. In other words, the receiver 13a is provided in parallel with a pipe between a portion where an upstream end of the suction bypass 8 meets the main circuit 30 and the outlet of the condenser 3.
- the check valve 14 prevents refrigerant from flowing from a main expansion valve 4 side into the receiver 13a.
- frost forms on the evaporator 5 during a hot-water supply operation.
- a reverse defrosting operation is performed.
- the reverse defrosting operation is an operation of removing frost forming on the evaporator 5 by switching the four-way valve 2 in directions indicated by dotted lines in Fig. 11 to supply high-temperature high-pressure gas refrigerant discharged from the compressor 1 to the evaporator 5.
- the check valve 14 prevents refrigerant from flowing into the receiver 13a during the reverse defrosting operation.
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure refrigerant discharged from the compressor 1 is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the discharged gas bypass 6 and is reduced in pressure by the discharged gas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it is bypassed to the suction side of the compressor 1.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3 via the four-way valve 2.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- the high-pressure refrigerant having flowed out of the condenser 3 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the suction bypass 8 via the main circuit 30, and refrigerant that is to flow through the other flow path is condensed and stored in the receiver 13a.
- the high-pressure refrigerant having flowed into the suction bypass 8 is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant.
- a flow of the high-temperature low-pressure gas that has been reduced in pressure by the discharged gas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by the suction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant, and the flow is sucked into the compressor 1 again.
- the receiver 13a is provided in parallel with the main circuit 30 on the outlet side of the condenser 3. This enables excess refrigerant to be stored in the receiver 13a even when refrigerant at the outlet of the condenser 3 is in a two-phase state.
- an operation in which liquid flows back to the suction side of the compressor 1 is prevented, thereby enabling a highly reliable negative pressure prevention operation to continue.
- Fig. 12 is a refrigerant circuit diagram of a refrigeration cycle apparatus illustrating Modification 2 of the refrigeration cycle apparatus according to Embodiment 4 of the present invention.
- a refrigerant circuit of Modification 2 of the refrigeration cycle apparatus according to Embodiment 4 includes an accumulator 15 in place of the receiver 13 of Fig. 10 . Note that the other components are the same as those in Fig. 10 .
- the accumulator 15 is provided on the suction side of the compressor 1 and is a refrigerant storage container that stores excess refrigerant caused during an operation.
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure refrigerant discharged from the compressor 1 is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the discharged gas bypass 6 and is reduced in pressure by the discharged gas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it is bypassed to the suction side of the compressor 1.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3 via the four-way valve 2.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- the high-pressure refrigerant having flowed out of the condenser 3 flows into the suction bypass 8, and the high-pressure refrigerant having flowed into the suction bypass 8 is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant.
- a flow of the high-temperature low-pressure gas that has been reduced in pressure by the discharged gas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by the suction bypass valve 9 combine to form a flow of low-temperature low-pressure refrigerant, and the flow is sucked into the compressor 1 again via the accumulator 15.
- the accumulator 15 is provided on the suction side of the compressor 1, thereby enabling excess refrigerant to be stored in the accumulator 15 during a negative pressure prevention operation in which excess refrigerant is caused. This prevents an operation in which liquid flows back to the suction side of the compressor 1, thereby enabling a highly reliable negative pressure prevention operation to continue.
- Embodiments 1 to 4 described above part of refrigerant discharged from the compressor 1 toward the condenser 3 is caused to flow into the discharged gas bypass 6 so that it is diverted from the main circuit 30, and the diverted refrigerant is caused to flow back to the suction side of the compressor 1. Then, in causing the diverted refrigerant to flow back to the suction side of the compressor 1, a flow of the diverted refrigerant is combined with a flow of refrigerant flowing through the suction bypass 8 on a downstream side of the suction bypass valve 9 and then caused to flow back.
- Embodiment 5 in causing diverted refrigerant that has been diverted from the main circuit 30 to flow back to the suction side of the compressor 1, a flow of the diverted refrigerant is combined with a flow of refrigerant that is to flow through the suction bypass 8 on an upstream side of the suction bypass valve 9 and then caused to flow back.
- Fig. 13 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 5 of the present invention and illustrates a state provided while a hot-water supply operation of raising the temperature of water on a load side is being performed. Furthermore, Fig. 14 is a P-h diagram illustrating an action state in an operation in Fig. 13 .
- Embodiment 5 the discharged gas bypass 6 and the discharged gas bypass valve 7 are removed from the structure in Embodiment 1 illustrated in Fig. 1 , whereas a condenser bypass 16 that bypasses the condenser 3 and a condenser bypass valve 17 that regulates a flow rate in the condenser bypass 16 are included.
- a bypass 41 in Embodiment 5 includes the condenser bypass 16 and the suction bypass 8, and is a circuit that combines a flow of refrigerant having flowed out of the condenser bypass 16 (part of refrigerant discharged from the compressor 1) and a flow of refrigerant having flowed out of the condenser 3 into a combined flow to allow the combined flow to flow into the suction side of the compressor 1 via the suction bypass 8.
- the suction bypass valve 9 constitutes the negative pressure regulating valve according to the present invention.
- the condenser bypass 16 bypasses part of discharged refrigerant discharged from the compressor 1 to the outlet side of the condenser 3.
- the condenser bypass valve 17 regulates a bypass flow rate of discharged gas to be passed through the condenser bypass 16.
- refrigerant ([1]) being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas ([2]), and discharged.
- the high-temperature high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the condenser bypass 16 and is reduced in pressure ([3]) by the condenser bypass valve 17, and then it flows out of the condenser bypass 16.
- a flow of the high-temperature high-pressure gas refrigerant having flowed out of the condenser bypass 16 and a flow of the high-pressure liquid refrigerant having flowed out of the condenser 3 combine to form a flow of high-pressure high-quality two-phase refrigerant ([5]).
- the two-phase refrigerant flows into the suction bypass 8 and is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure gas refrigerant ([1]), and the low-temperature low-pressure gas refrigerant is sucked into the compressor 1 again.
- the main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into the evaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur.
- a compressor suction pressure is controlled by the discharged gas bypass valve 7.
- a flow of refrigerant ([3]) having flowed out of the condenser bypass 16 and a flow of refrigerant ([4]) having flowed out of the condenser 3 combine to form a combined flow, and refrigerant in the combined flow is reduced in pressure by the suction bypass valve 9 and sucked into the compressor 1.
- a compressor suction pressure is controlled by the suction bypass valve 9.
- Fig. 15 is a system configuration diagram of the refrigeration cycle apparatus according to Embodiment 5 of the present invention.
- the refrigeration cycle apparatus differs from that illustrated in Fig. 4 in that the controller 20 is connected in such a manner as to be able to control the condenser bypass valve 17 in place of the discharged gas bypass valve 7 in the system configuration in Embodiment 1 illustrated in Fig. 4 .
- the controller 20 includes a negative pressure prevention control unit 20A and a superheat degree control unit 20B.
- the negative pressure prevention control unit 20A performs a negative pressure prevention operation of controlling the opening degree of the suction bypass valve 9 to prevent a suction pressure of the compressor 1 from becoming negative.
- the superheat degree control unit 20B regulates the opening degree of the condenser bypass valve 17 so that a degree of superheat of gas to be sucked into the compressor 1 becomes a setting value set in advance.
- the negative pressure prevention control unit 20A and the superheat degree control unit 20B are functionally configured by the CPU and the control program. Configurations other than these are the same as those illustrated in Fig. 4 .
- Fig. 16 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according to Embodiment 5 of the present invention.
- the flowchart in Embodiment 5 illustrated in Fig. 16 differs from that in Embodiment 1 in the following respects. That is, control of the opening degree of the discharged gas bypass valve 7 in steps S6 and S7 in Fig. 5 is replaced with control of the opening degree of the suction bypass valve 9 in steps S6a and S7a in Fig. 16 . Furthermore, control of the opening degree of the suction bypass valve 9 in steps S11 and S12 in Fig.
- Embodiment 5 is replaced with control of the opening degree of the condenser bypass valve 17 in Fig. 16 .
- the other steps are the same as those in the control flowchart of Fig. 5 .
- a description will be given below with emphasis on a respect in which control of the negative pressure prevention operation in Embodiment 5 differs from that in Embodiment 1.
- Embodiment 5 as a result of a comparison of a compressor suction pressure Ps and a setting value 2 set in advance in step S5, when the compressor suction pressure Ps is lower than the setting value 2, the opening degree of the suction bypass valve 9 is increased (S6a). Thus, the compressor suction pressure Ps rises and approaches the setting value 2. On the other hand, when the compressor suction pressure Ps is higher than the setting value 2, the opening degree of the suction bypass valve 9 is reduced (S7a). Thus, the compressor suction pressure Ps falls and approaches the setting value 2.
- Embodiment 5 as a result of a comparison of a compressor suction superheat degree SHs and a setting value 3 that has been set in advance as a target value of a compressor suction superheat degree in step S10, when the compressor suction superheat degree SHs is lower than the setting value 3, the controller 20 increases the opening degree of the condenser bypass valve 17 (S11a). Thus, the compressor suction superheat degree SHs rises and approaches the setting value 3. On the other hand, when the compressor suction superheat degree SHs is higher than the setting value 3, the opening degree of the condenser bypass valve 17 is reduced (S12a). Thus, the compressor suction superheat degree SHs falls and approaches the setting value 3. Then, after the process of S11a or S12a, the controller 20 returns to S5 and repeatedly performs control so that the compressor suction pressure Ps and the compressor suction superheat degree SHs respectively become equal to the corresponding setting value 2 and setting value 3.
- the refrigeration cycle apparatus differs from that in Embodiment 1 in bypass valves to be controlled, but can produce the same effect as that in Embodiment 1. That is, when an operation state in which an outdoor air temperature is low and a compressor suction pressure is close to a negative pressure is entered, a hot-water supply operation is continued with the main expansion valve 4 being fully closed without evaporation of refrigerant in the evaporator 5. Then, the compressor suction pressure is controlled by using the opening degree of the suction bypass valve 9, and a suction superheat degree of the compressor 1 is also controlled by using the opening degree of the condenser bypass valve 17.
- Embodiment 6 corresponds to, so to speak, a combination of Embodiment 5 and Embodiment 4 in which the receiver 13 is included. A description will be given below with emphasis on a respect in which Embodiment 6 differs from Embodiment 5.
- Fig. 17 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 6 of the present invention.
- a system configuration diagram of the refrigeration cycle apparatus according to Embodiment 6 includes the receiver 13. Note that the other components are the same as those in Embodiment 5 illustrated in Fig. 13 .
- the receiver 13 is disposed on a pipe connecting the condenser 3 and the suction bypass valve 9 and stores excess refrigerant caused during an operation.
- Refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the condenser bypass 16 and is reduced in pressure by the condenser bypass valve 17, and then it flows out of the condenser bypass 16.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant and flows into the receiver 13.
- a flow of the high-temperature high-pressure gas refrigerant having flowed out of the condenser bypass 16 and a flow of the high-pressure liquid refrigerant having flowed out of the receiver 13 combine to form a flow of high-pressure high-quality two-phase refrigerant, and the flow flows into the suction bypass 8.
- the two-phase refrigerant having flowed into the suction bypass 8 is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure gas refrigerant, and the low-temperature low-pressure gas refrigerant is sucked into the compressor 1 again.
- the refrigeration cycle apparatus produces the same effect as that in Embodiment 5 and also produces the following effect. That is, excess refrigerant can be stored in the receiver 13 during a negative pressure prevention operation, thereby preventing an operation in which liquid flows back to the suction side of the compressor 1 and enabling a highly reliable negative pressure prevention operation to continue.
- Embodiment 6 presents the structure including a refrigerant storage container (the receiver 13 herein), the disposition of the refrigerant storage container is not limited to the disposition illustrated in Fig. 17 , and modifications can be made as described in the following Modifications 1 and 2.
- Fig. 18 is a refrigerant circuit diagram of Modification 1 of the refrigeration cycle apparatus according to Embodiment 6 of the present invention.
- a refrigerant circuit of Modification 1 of the refrigeration cycle apparatus according to Embodiment 6 includes the receiver 13a and the check valve 14 in place of the receiver 13 of Fig. 17 .
- the other components are the same as those in Fig. 17 .
- the receiver 13a is a refrigerant storage container that stores excess refrigerant caused during an operation.
- the receiver 13a is provided in parallel with the main circuit 30 on the outlet side of the condenser 3. In other words, the receiver 13a is provided in parallel with a pipe between a portion where a downstream end of the condenser bypass 16 meets the main circuit 30 and the outlet of the condenser 3.
- the check valve 14 prevents refrigerant from flowing from the main expansion valve 4 side into the receiver 13a.
- frost forms on the evaporator 5 during a hot-water supply operation.
- a reverse defrosting operation is performed.
- the reverse defrosting operation is an operation of removing frost forming on the evaporator 5 by switching the four-way valve 2 in directions indicated by dotted lines in Fig. 18 to supply high-temperature high-pressure gas refrigerant discharged from the compressor 1 to the evaporator 5.
- the check valve 14 prevents the inflow of refrigerant during the reverse defrosting operation.
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the condenser bypass 16 and is reduced in pressure by the condenser bypass valve 17, and then it flows out of the condenser bypass 16.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- the high-pressure refrigerant having flowed out of the condenser 3 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the main circuit 30, and refrigerant that is to flow through the other flow path is condensed and stored in the receiver 13a. A flow of the high-pressure refrigerant having flowed into the main circuit 30 combines with a flow of the high-temperature high-pressure gas refrigerant having flowed out of the condenser bypass 16 to form a flow of high-pressure high-quality two-phase refrigerant.
- the two-phase refrigerant flows into the suction bypass 8 and is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure gas refrigerant, and the low-temperature low-pressure gas refrigerant is sucked into the compressor 1 again.
- the receiver 13a is provided in parallel with the main circuit 30 on the outlet side of the condenser 3. This enables excess refrigerant to be stored in the receiver 13a even when refrigerant at the outlet of the condenser 3 is in a two-phase state.
- an operation in which liquid flows back to the suction side of the compressor 1 is prevented, thereby enabling a highly reliable negative pressure prevention operation to continue.
- Fig. 19 is a refrigerant circuit diagram of Modification 2 of the refrigeration cycle apparatus according to Embodiment 6 of the present invention.
- a refrigerant circuit of Modification 2 of the refrigeration cycle apparatus according to Embodiment 6 includes the accumulator 15 in place of the receiver 13 of Fig. 17 . Note that the other components are the same as those in Fig. 17 .
- the accumulator 15 is provided on the suction side of the compressor 1 and stores excess refrigerant caused during an operation.
- refrigerant being in a low-temperature low-pressure gas state is sucked into the compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged.
- the high-temperature high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths.
- Refrigerant that is to flow through one flow path flows into the condenser bypass 16 and is reduced in pressure by the condenser bypass valve 17, and then it flows out of the condenser bypass 16.
- Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the condenser 3.
- the high-temperature high-pressure gas refrigerant having flowed into the condenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant.
- a flow of the high-temperature high-pressure gas refrigerant having flowed out of the condenser bypass 16 and a flow of the high-pressure liquid refrigerant having flowed out of the condenser 3 combine to form a flow of high-pressure high-quality two-phase refrigerant, and the flow flows into the suction bypass 8.
- the two-phase refrigerant having flowed into the suction bypass 8 is reduced in pressure and expanded by the suction bypass valve 9 to turn into low-temperature low-pressure refrigerant, and the low-temperature low-pressure refrigerant is sucked into the compressor 1 again via the accumulator 15.
- the accumulator 15 is provided on the suction side of the compressor 1, thereby enabling excess refrigerant to be stored in the accumulator 15 during a negative pressure prevention operation in which excess refrigerant is caused. This prevents an operation in which liquid flows back to the suction side of the compressor 1, thereby enabling a highly reliable negative pressure prevention operation to continue.
- refrigerant a single refrigerant of HFO-1234yf, a single refrigerant of HFO-1234ze, or a refrigerant mixture of HFO-1234yf or HFO-1234ze and R32 is used.
- refrigerant may be any refrigerant that has a higher boiling point than R407C.
- refrigerant it is desirable that refrigerant be refrigerant whose global warming potential is lower than that of R407C.
- the refrigeration cycle apparatus is used for a heat pump water heater
- the refrigeration cycle apparatus can also be used for an air-conditioning apparatus, for example.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
Description
- The present invention relates to a refrigeration cycle apparatus for a heat pump water heater or other apparatuses.
- As an existing refrigeration cycle apparatus, for example, an apparatus has been proposed in which "HFO-1234yf is used as refrigerant, at least a compressor, a condenser, an expansion device, and an evaporator are sequentially connected to form a circular refrigerant circuit, a four-way valve is provided to switch between directions in which the refrigerant flows, an indoor heat exchanger and an outdoor heat exchanger are respectively caused to work as an evaporator and a condenser in a cooling operation, and the indoor heat exchanger and the outdoor heat exchanger are respectively caused to work as a condenser and an evaporator in a heating operation" (see
Patent Literature 1, orWO 2013/160967 A1 , for example).US 2011/132006 A1 describes a refrigeration cycle apparatus using a compressor discharge bypass and a suction bypass combining the flow of the compressor discharge bypass with a refrigerant flow downstream the condenser and routing the combined flow to the suction side of the compressor. Furthermore, a negative pressure prevention valve is controlled such that negative compressor suction pressure is avoided. - Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2011-252638 - HFO-1234yf used in the technique disclosed in
Patent Literature 1 is refrigerant having a higher boiling point than refrigerant, such as R407C and R410A, having been used. For this reason, the refrigerant has the property that a compressor suction pressure decreases. Thus, when a heating operation is performed under low outdoor air temperature conditions in particular, the operation is performed in a negative pressure state in which a compressor suction pressure is lower than an atmospheric pressure, thereby causing the problem of the occurrence of a disadvantage, such as a malfunction due to suction of air. - The present invention has been made to solve a problem like that described above and provides a refrigeration cycle apparatus that, even when refrigerant having a higher boiling point than R407C refrigerant is used, can prevent a compressor suction pressure from falling to or below an atmospheric pressure under low outdoor air temperature conditions and increase reliability.
- The above problem is solved by the present invention providing a refrigeration cycle apparatus with the features of
claim 1 and a refrigeration cycle apparatus with the features ofclaim 6. - According to the present invention, a refrigeration cycle apparatus can be obtained that, even when refrigerant having a higher boiling point than R407C refrigerant is used, can prevent a compressor suction pressure from falling to or below an atmospheric pressure under low outdoor air temperature conditions and increase reliability.
-
- [
Fig. 1] Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus according toEmbodiment 1 of the present invention. - [
Fig. 2] Fig. 2 is a graph illustrating comparisons of relationships between saturation temperatures and saturated vapor pressures of various types of refrigerant. - [
Fig. 3] Fig. 3 is a P-h diagram illustrating an action state in a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 1 of the present invention. - [
Fig. 4] Fig. 4 is a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 1 of the present invention. - [
Fig. 5] Fig. 5 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 1 of the present invention. - [
Fig. 6] Fig. 6 is a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 2 of the present invention. - [
Fig. 7] Fig. 7 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 2 of the present invention. - [
Fig. 8] Fig. 8 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 3 of the present invention. - [
Fig. 9] Fig. 9 is a schematic view of an ejector ofFig. 8 . - [
Fig. 10] Fig. 10 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 4 of the present invention. - [
Fig. 11] Fig. 11 is a refrigerant circuit diagram of a refrigeration cycleapparatus illustrating Modification 1 of the refrigeration cycle apparatus according toEmbodiment 4 of the present invention. - [
Fig. 12] Fig. 12 is a refrigerant circuit diagram of a refrigeration cycleapparatus illustrating Modification 2 of the refrigeration cycle apparatus according toEmbodiment 4 of the present invention. - [
Fig. 13] Fig. 13 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 5 of the present invention. - [
Fig. 14] Fig. 14 is a P-h diagram illustrating an action state in an operation inFig. 13 . - [
Fig. 15] Fig. 15 is a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 5 of the present invention. - [
Fig. 16] Fig. 16 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 5 of the present invention. - [
Fig. 17] Fig. 17 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 6 of the present invention. - [
Fig. 18] Fig. 18 is a refrigerant circuit diagram ofModification 1 of the refrigeration cycle apparatus according toEmbodiment 6 of the present invention. - [
Fig. 19] Fig. 19 is a refrigerant circuit diagram ofModification 2 of the refrigeration cycle apparatus according toEmbodiment 6 of the present invention. - A refrigeration cycle apparatus according to Embodiments of the present invention will be described below with reference to the drawings, for example. Here, in the following drawings including
Fig. 1 , components denoted by the same reference numerals are the same or corresponding components, and this is common throughout Embodiments to be described below. Then, the forms of components described throughout the specification are merely illustrative, and forms are not limited to the forms described in the specification. In particular, combinations of components are not limited to only those in each Embodiment, and a component described in one Embodiment can be used in another Embodiment. In addition, high and low levels of temperature, pressure, or other measurements are not determined in relation to an absolute value in particular, but are relatively determined in accordance with the state or action of a system or an apparatus, for example. - Furthermore, the case where the refrigeration cycle apparatus is used for a heat pump water heater is taken as an example below to describe Embodiments.
-
Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus according toEmbodiment 1 of the present invention and illustrates a state provided while a heating operation (hot-water supply operation) of raising the temperature of water on a load side is being performed. - The refrigeration cycle apparatus according to
Embodiment 1 includes amain circuit 30 in which acompressor 1, a four-way valve 2, acondenser 3, amain expansion valve 4, and anevaporator 5 are connected in a circle, and through which refrigerant circulates, abypass 40, and a dischargedgas bypass valve 7 serving as a negative pressure regulating valve that regulates a flow rate in thebypass 40. - The
compressor 1 is constituted by, for example, an inverter compressor capable of controlling capacity, sucks low-temperature low-pressure gas refrigerant, compresses the refrigerant to turn it into a high-temperature high-pressure gas refrigerant state, and discharges thereof. - The four-
way valve 2 switches a direction in which the high-temperature high-pressure gas refrigerant discharged from thecompressor 1 flows to the direction of thecondenser 3 or theevaporator 5. - The
condenser 3 is constituted by a plate-type heat exchanger and exchanges heat between refrigerant flowing through themain circuit 30 and a medium to be subjected to heat exchange supplied from a cooling load (not illustrated) to transfer heat. - The
main expansion valve 4 reduces the pressure of high-pressure refrigerant to turn the refrigerant into low-pressure two-phase refrigerant. - The
evaporator 5 is constituted by, for example, a plate-fin-type heat exchanger and exchanges heat between refrigerant and air to evaporate the refrigerant. - The
bypass 40 includes a dischargedgas bypass 6 and asuction bypass 8, and is a circuit that combines a flow of part of refrigerant discharged from thecompressor 1 and a flow of refrigerant having flowed out of thecondenser 3 into a combined flow to allow the combined flow to flow into a suction side of thecompressor 1. - The discharged
gas bypass 6 bypasses part of discharged refrigerant discharged from thecompressor 1 to the suction side of thecompressor 1. The dischargedgas bypass valve 7 is provided in the dischargedgas bypass 6 and regulates a bypass flow rate of discharged gas to be passed through the dischargedgas bypass 6. An increase in the opening degree of the dischargedgas bypass valve 7 increases a flow rate of refrigerant passing through the dischargedgas bypass 6 and returning to the suction side of thecompressor 1 and increases a compressor suction pressure. On the other hand, a reduction in the opening degree of the dischargedgas bypass valve 7 reduces a flow rate of refrigerant passing through the dischargedgas bypass 6 and returning to the suction side of thecompressor 1 and reduces a compressor suction pressure. - The
suction bypass 8 combines a flow of high-pressure refrigerant at an outlet of thecondenser 3 into a flow in the dischargedgas bypass 6 to allow the flow to flow into the suction side of thecompressor 1. Asuction bypass valve 9 is provided in thesuction bypass 8 and regulates a flow rate of refrigerant to be passed through thesuction bypass 8. An increase in the opening degree of thesuction bypass valve 9 increases a flow rate of high-pressure refrigerant passing through thesuction bypass 8 and flowing into the suction side of thecompressor 1 and thus reduces a compressor suction superheat degree. On the other hand, a reduction in the opening degree of thesuction bypass valve 9 reduces a flow rate of high-pressure refrigerant flowing from thesuction bypass 8 into the suction side of thecompressor 1 and thus increases a compressor suction superheat degree. - Here, in
Embodiment 1, refrigerant containing HFO-1234yf refrigerant or HFO-1234ze refrigerant is used as refrigerant. Refrigerant may be a single refrigerant of HFO-1234yf, a single refrigerant of HFO-1234ze, or a refrigerant mixture containing HFO-1234yf or HFO-1234ze. In the case of a refrigerant mixture, R32 can be used, for example. A global warming potential (GWP) of the HFO-1234yf refrigerant or the HFO-1234ze refrigerant is "4", which is lower than "2090" of existing R410A refrigerant and "1770" of R407C refrigerant, and thus the HFO-1234yf refrigerant or the HFO-1234ze refrigerant is refrigerant that has less impact on the global environment. - Next, the action of a refrigeration cycle of the refrigeration cycle apparatus according to
Embodiment 1 will be described with reference toFig. 1 . - First, a normal hot-water supply operation will be described.
- During a normal hot-water supply operation, the discharged
gas bypass valve 7 and thesuction bypass valve 9 are fully closed, and refrigerant does not flow through the dischargedgas bypass 6 and thesuction bypass 8. In the normal hot-water supply operation, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure refrigerant discharged from thecompressor 1 flows into thecondenser 3 via the four-way valve 2. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. The high-pressure liquid refrigerant having flowed out of thecondenser 3 flows into themain expansion valve 4 and is reduced in pressure and expanded to turn into low-temperature low-pressure two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant having flowed out of themain expansion valve 4 flows into theevaporator 5, cools air serving as a medium to be subjected to heat exchange, and evaporates to turn into low-temperature low-pressure gas refrigerant. The low-temperature low-pressure gas refrigerant having flowed out of theevaporator 5 passes through the four-way valve 2 again and then is sucked into thecompressor 1 again. - Here, for R410A refrigerant and R407C refrigerant that have been used, and for HFO-1234yf refrigerant and HFO-1234ze that are used in
Embodiment 1, relationships between saturation temperatures and saturated vapor pressures will be described. -
Fig. 2 is a graph illustrating comparisons of relationships between saturation temperatures and saturated vapor pressures of various types of refrigerant. Here, as various types of refrigerant, R410A refrigerant, R407C refrigerant, HFO-1234yf refrigerant, and HFO-1234ze are illustrated. InFig. 2 , the horizontal axis represents saturation temperature [DEGREES C], and the vertical axis represents saturated vapor pressure [MPa (abs)]. - According to
Fig. 2 , in terms of saturated vapor pressure, the HFO-1234yf refrigerant used inEmbodiment 1 is lower than the R410A refrigerant and R407C refrigerant that have been used. Thus, when a hot-water supply operation is performed in a very cold area where an outdoor air temperature is equal to or less than -25 degrees C, for example, it is conceivable that an evaporating temperature may fall below a saturated vapor temperature of -29.5 degrees C at an atmospheric pressure, resulting in a negative pressure operation in which a compressor suction pressure is equal to or less than the atmospheric pressure. When the compressor suction pressure becomes negative, air is sucked into the refrigeration cycle, resulting in the occurrence of a disadvantage, such as a malfunction of the refrigeration cycle. - Thus, the refrigeration cycle apparatus according to
Embodiment 1 performs a negative pressure prevention operation of continuing a hot-water supply operation with a compressor suction pressure being equal to or greater than a negative pressure even under low outdoor air temperature conditions. - Next, the action of a refrigeration cycle in a negative pressure prevention operation will be described with reference to the refrigerant circuit diagram of
Fig. 1 and the following P-h diagram ofFig. 3 . -
Fig. 3 is a P-h diagram illustrating an action state in a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 1 of the present invention. InFig. 3 , [1] to [5] respectively indicate refrigerant states at positions of [1] to [5] inFig. 1 . Note that, during the negative pressure prevention operation, the opening degree of themain expansion valve 4 is in a substantially-closed state. An opening degree being in the "substantially-closed" state refers to not only an opening degree being in a fully-closed state but also such an exceedingly small opening degree that has no adverse effect in preventing negative pressure. That is, an opening degree being in the "substantially-closed" state corresponds to an opening degree being in a fully-closed state or in a state close to the fully-closed state. When themain expansion valve 4 is open during a heating operation under low outdoor air temperature conditions, refrigerant flows into theevaporator 5, resulting in a reduction in compressor suction pressure. Thus, in the negative pressure prevention operation, themain expansion valve 4 is closed so that refrigerant does not flow into theevaporator 5. - In a negative pressure prevention operation in the refrigeration cycle apparatus according to
Embodiment 1, refrigerant ([1]) being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure refrigerant ([2]) discharged from thecompressor 1 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the dischargedgas bypass 6 and is reduced in pressure by the dischargedgas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant ([3]), and it is bypassed to the suction side of thecompressor 1. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3 via the four-way valve 2. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant ([4]). - The high-pressure liquid refrigerant having flowed out of the
condenser 3 flows into thesuction bypass 8 and is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant ([5]). A flow of the high-temperature low-pressure gas ([3]) that has been reduced in pressure by the dischargedgas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant ([5]) that has been reduced in pressure and expanded by thesuction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant ([1]), and the flow is sucked into thecompressor 1 again. Note that, since themain expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. - Here, a general description of a negative pressure prevention operation will be given.
- The negative pressure prevention operation is started when an operation state in which a compressor suction pressure is close to a negative pressure is entered, and is an operation that causes little refrigerant to flow into the
evaporator 5 and causes most of high-pressure refrigerant having flowed out of thecondenser 3 to flow into thesuction bypass 8. Then, the dischargedgas bypass valve 7 is controlled so that a compressor suction pressure becomes higher than the negative pressure, thereby preventing negative pressure. InEmbodiment 1, in addition to control of the dischargedgas bypass valve 7, thesuction bypass valve 9 is also controlled so that a compressor suction superheat degree is put into an appropriate state. -
Fig. 4 is a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 1 of the present invention.Fig. 5 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 1 of the present invention. - As illustrated in
Fig. 4 , the refrigeration cycle apparatus according toEmbodiment 1 includes acontroller 20, a compressorsuction pressure sensor 21, and a compressorsuction temperature sensor 22. Note that the other components are the same as those inFig. 1 . - The
controller 20 controls the entire refrigeration cycle apparatus. Thecontroller 20 is constituted by a microcomputer, for example, and includes a CPU, a RAM, a ROM, and other components. In the ROM, a control program and a program corresponding to the flowchart ofFig. 5 are stored. - The compressor
suction pressure sensor 21 and the compressorsuction temperature sensor 22 are connected to thecontroller 20 so that detection signals from the respective sensors can be received. Based on, for example, these detection signals, thecontroller 20 controls the opening degree of themain expansion valve 4, the opening degree of the dischargedgas bypass valve 7, and the opening degree of thesuction bypass valve 9, for example. Thecontroller 20 also controls, based on, for example, detection signals from therespective sensors - Next, functional components of the
controller 20 will be described. Thecontroller 20 includes a negative pressureprevention control unit 20a and a superheatdegree control unit 20b. The negative pressureprevention control unit 20a performs a negative pressure prevention operation of controlling the dischargedgas bypass valve 7 to prevent a suction pressure of thecompressor 1 from becoming negative. The superheatdegree control unit 20b regulates the opening degree of thesuction bypass valve 9 so that a degree of superheat of gas to be sucked into thecompressor 1 becomes a setting value set in advance. The negative pressureprevention control unit 20a and the superheatdegree control unit 20b are functionally configured by the CPU and the control program. - Next, a control action in a negative pressure prevention operation in the refrigeration cycle apparatus according to
Embodiment 1 will be described with reference toFigs. 4 and5 . - The
controller 20 acquires a compressor suction pressure Ps detected by the compressor suction pressure sensor 21 (S1). Then, thecontroller 20 compares the compressor suction pressure Ps with a setting value 1 (It is, for example, 0.01 MPa (G), which is a setting value representing at least a positive pressure.) that has been set in advance and is an upper limit pressure at which a negative pressure prevention operation is started (S2). While the compressor suction pressure Ps is equal to or greater than the settingvalue 1, thecontroller 20 returns to step S1, and a normal hot-water supply operation is continued. On the other hand, when the compressor suction pressure Ps falls below the settingvalue 1, thecontroller 20 determines that the refrigeration cycle apparatus is in an operation state in which an outdoor air temperature is low and the compressor suction pressure is close to a negative pressure, and starts the negative pressure prevention operation (S3). - In the negative pressure operation, first, the
controller 20 substantially closes the main expansion valve 4 (its opening degree is reduced to an opening degree being in a fully-closed state or in a state close to the fully-closed state) (S4). Subsequently, thecontroller 20 compares a setting value 2 (It is, for example, 0.02 MPa (G), which is a setting value representing at least a positive pressure.) that has been set in advance as a target value of a compressor suction pressure with the compressor suction pressure Ps (S5). Then, when the compressor suction pressure Ps is lower than the setting value 2 (> the setting value 1), thecontroller 20 increases the opening degree of the discharged gas bypass valve 7 (S6). Thus, the compressor suction pressure Ps rises and approaches the settingvalue 2. On the other hand, when the compressor suction pressure Ps is higher than the settingvalue 2, the opening degree of the dischargedgas bypass valve 7 is reduced (S7). Thus, the compressor suction pressure Ps falls and approaches the settingvalue 2. Note that, although not illustrated inFig. 5 , when the compressor suction pressure Ps is equal to the settingvalue 2, the opening degree of the dischargedgas bypass valve 7 may remain unchanged. - Subsequently, the
controller 20 acquires a compressor suction temperature Ts detected by the compressorsuction temperature sensor 22. Then, thecontroller 20 calculates a compressor suction superheat degree SHs by using the acquired compressor suction temperature Ts (S9). That is, thecontroller 20 calculates a saturation temperature f(Ps) of the compressor suction pressure Ps and subtracts the saturation temperature f(Ps) of the compressor suction pressure Ps from the compressor suction temperature Ts to get a compressor suction superheat degree SHs. - Subsequently, the
controller 20 compares the calculated compressor suction superheat degree SHs with a setting value 3 (for example, 5 K) that has been set in advance as a target value of a compressor suction superheat degree (S10). Then, when the compressor suction superheat degree SHs is lower than the settingvalue 3, thecontroller 20 reduces the opening degree of the suction bypass valve 9 (S11). Thus, the compressor suction superheat degree SHs rises and approaches the settingvalue 3. On the other hand, when the compressor suction superheat degree SHs is higher than the settingvalue 3, the opening degree of thesuction bypass valve 9 is increased (S12). Thus, the compressor suction superheat degree SHs falls and approaches the settingvalue 3. Note that, although not illustrated inFig. 5 , when the compressor suction superheat degree SHs is equal to the settingvalue 3, the opening degree of thesuction bypass valve 9 may remain unchanged. Then, after the process of S11 or S12, thecontroller 20 returns to S5 and repeatedly performs control so that the compressor suction pressure Ps and the compressor suction superheat degree SHs respectively become equal to thecorresponding setting value 2 and settingvalue 3. - As described above, when the refrigeration cycle apparatus according to
Embodiment 1 enters an operation state in which an outdoor air temperature is low and a compressor suction pressure is close to a negative pressure, the refrigeration cycle apparatus continues a hot-water supply operation with themain expansion valve 4 being fully closed without evaporation of refrigerant in theevaporator 5. Then, the compressor suction pressure is controlled by using the opening degree of the dischargedgas bypass valve 7, and a compressor suction superheat degree is also controlled by using the opening degree of thesuction bypass valve 9. This prevents the compressor suction pressure from becoming negative and also enables the hot-water supply operation to continue with the compressor suction superheat degree being appropriate. Thus, even when an outdoor air temperature falls, a disadvantage, such as a malfunction due to suction of air, can be avoided. Furthermore, in a water heater, a hot-water supply operation of raising the temperature of water does not have to be stopped even under low outdoor air temperature conditions, thus making it possible to prevent water pipes from freezing, for example. - In
Embodiment 2, a two-way valve is further included in the structure inEmbodiment 1 illustrated inFig. 1 . Note that the other components are the same as those inFig. 1 . A description will be given below with emphasis on a respect in whichEmbodiment 2 differs fromEmbodiment 1. -
Fig. 6 is a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 2 of the present invention.Fig. 7 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 2 of the present invention. - As illustrated in
Fig. 6 , the refrigeration cycle apparatus according toEmbodiment 2 further includes a two-way valve 10 in addition to the structure inEmbodiment 1. - The two-
way valve 10 is disposed between the four-way valve 2 and theevaporator 5 and interrupts the flow of refrigerant between the four-way valve 2 and theevaporator 5 by closing the two-way valve 10. - Next, the control action of the refrigeration cycle apparatus according to
Embodiment 2 will be described with reference toFigs. 6 and7 . Note that a normal hot-water supply operation is the same as that inEmbodiment 1, and thus a description thereof is omitted. Only a negative pressure prevention operation will be described. - A negative pressure prevention operation in the refrigeration cycle apparatus according to
Embodiment 2 differs from that inEmbodiment 1 in that a step of closing the two-way valve 10 (S21) is further included in the flowchart inEmbodiment 1 illustrated inFig. 5 , and the other steps are the same as those inEmbodiment 1. It is only necessary that the step of closing the two-way valve 10 be provided between step S3 and step S5. - As described above, the refrigeration cycle apparatus according to
Embodiment 2 produces the same effect as that inEmbodiment 1 and also produces the following effect. That is, closing the two-way valve 10 during a negative pressure prevention operation can prevent low-pressure high-temperature refrigerant (refrigerant indicated by a dotted arrow inFig. 6 ) having flowed out of the dischargedgas bypass valve 7 from flowing into thecold evaporator 5 via the four-way valve 2, condensing, and accumulating. This does not result in any lack of refrigerant circulating through the dischargedgas bypass 6 and thesuction bypass 8 and enables the negative pressure prevention operation to continue. - In
Embodiment 3, an ejector and a suction pipe are further included in the structure inEmbodiment 1 illustrated inFig. 1 . Note that the other components are the same as those inFig. 1 . A description will be given below with emphasis on a respect in whichEmbodiment 3 differs fromEmbodiment 1. -
Fig. 8 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 3 of the present invention. - An
ejector 11 is disposed on a downstream side of the dischargedgas bypass valve 7 of the dischargedgas bypass 6 and sucks refrigerant on anevaporator 5 side via asuction pipe 12. -
Fig. 9 is a schematic view of the ejector ofFig. 8 . - The
ejector 11 is constituted by three sections: anozzle 11a, anexpansion section 11b, and adiffuser 11c. A main flow flowing in from an inlet is throttled by thenozzle 11a and put into a state in which its flow velocity at theexpansion section 11b is higher than that at the inlet. Assuming that the pressure, flow velocity, and density of refrigerant at the inlet are respectively P1, v1, and p1, and that the pressure, flow velocity, and density of refrigerant at theexpansion section 11b are respectively P2, v2, and p2, the following relationship holds based on Bernoulli's equation. - Here, because the relationship between the flow velocity v2 at the
expansion section 11b and the flow velocity v1 at the inlet is v2 > v1, the relationship between the respective pressures is P2 < P1, a pressure differential of P1 - P2 is created in arefrigerant suction section 11d, and refrigerant is sucked. - Next, the action of a refrigeration cycle of the refrigeration cycle apparatus according to
Embodiment 3 will be described with reference toFig. 8 . Note that the action of a refrigeration cycle in a normal hot-water supply operation is the same as that inEmbodiment 1, and thus a description thereof is omitted. Only a negative pressure prevention operation will be described. In the negative pressure prevention operation, the fact that themain expansion valve 4 is substantially closed is the same as that inEmbodiment 1. - In a negative pressure prevention operation in the refrigeration cycle apparatus according to
Embodiment 3, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure refrigerant discharged from thecompressor 1 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the dischargedgas bypass 6 and is reduced in pressure by the dischargedgas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it flows into theejector 11. In theejector 11, a refrigerant pressure decreases as a refrigerant flow velocity increases, and refrigerant on theevaporator 5 side is sucked via thesuction pipe 12 connected to therefrigerant suction section 11d. - Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into the
condenser 3 via the four-way valve 2. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. The high-pressure liquid refrigerant having flowed out of thecondenser 3 flows into thesuction bypass 8 and is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant. A flow of the high-temperature low-pressure gas that has been reduced in pressure by the dischargedgas bypass valve 7 and passed through theejector 11 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by thesuction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant, and the flow is sucked into thecompressor 1 again. - As described above, the refrigeration cycle apparatus according to
Embodiment 3 produces the same effect as that inEmbodiment 1 and also produces the following effect. That is, even when low-pressure high-temperature refrigerant having flowed out of the dischargedgas bypass valve 7 flows into thecold evaporator 5 via the four-way valve 2 during a negative pressure prevention operation, the refrigerant having flowed to theevaporator 5 side is sucked by theejector 11 to enable the refrigerant to be drawn back to the dischargedgas bypass 6. Thus, refrigerant having flowed out of the dischargedgas bypass valve 7 and flowed into theevaporator 5 can be prevented from condensing and accumulating in theevaporator 5. This does not result in any lack of refrigerant circulating through the dischargedgas bypass 6 and thesuction bypass 8 and enables the negative pressure prevention operation to continue. - In
Embodiment 4, a receiver is further included in the structure inEmbodiment 1 illustrated inFig. 1 . Note that the other components are the same as those inFig. 1 . A description will be given below with emphasis on a respect in whichEmbodiment 4 differs fromEmbodiment 1. -
Fig. 10 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 4 of the present invention. - A
receiver 13 is disposed on a pipe connecting thecondenser 3 and thesuction bypass valve 9 and stores excess refrigerant caused during an operation. - Next, the action of a refrigeration cycle according to
Embodiment 4 will be described with reference toFig. 10 . Note that a normal hot-water supply operation is the same as that inEmbodiment 1, and thus a description thereof is omitted. Only a negative pressure prevention operation will be described. In the negative pressure prevention operation, the fact that themain expansion valve 4 is substantially closed is the same as that inEmbodiment 1. - In a negative pressure prevention operation in the refrigeration cycle apparatus according to
Embodiment 4, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure refrigerant discharged from thecompressor 1 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the dischargedgas bypass 6 and is reduced in pressure by the dischargedgas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it is bypassed to the suction side of thecompressor 1. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3 via the four-way valve 2. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. The high-pressure liquid refrigerant having flowed out of thecondenser 3 flows into thesuction bypass 8 via thereceiver 13 and is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant. A flow of the high-temperature low-pressure gas that has been reduced in pressure by the dischargedgas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by thesuction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant, and the flow is sucked into thecompressor 1 again. - Note that, since the
main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. Thus, theevaporator 5 is not used in the negative pressure prevention operation, and the necessary amount of refrigerant is smaller than that in a normal hot-water supply operation. This causes excess refrigerant in the negative pressure prevention operation. InEmbodiment 4, however, excess refrigerant can be stored in thereceiver 13. - As described above, the refrigeration cycle apparatus according to
Embodiment 4 produces the same effect as that inEmbodiment 1 and also produces the following effect. That is, excess refrigerant can be stored in thereceiver 13 during a negative pressure prevention operation, thereby preventing an operation in which liquid flows back to the suction side of thecompressor 1 and enabling a highly reliable negative pressure prevention operation to continue. - Although
Embodiment 4 presents the structure including a refrigerant storage container (thereceiver 13 herein), the disposition of the refrigerant storage container is not limited to the disposition illustrated inFig. 10 , and modifications can be made as described in the followingModifications -
Fig. 11 is a refrigerant circuit diagram of a refrigeration cycleapparatus illustrating Modification 1 of the refrigeration cycle apparatus according toEmbodiment 4 of the present invention. - As illustrated in
Fig. 11 , a refrigerant circuit ofModification 1 of the refrigeration cycle apparatus according toEmbodiment 4 includes areceiver 13a and acheck valve 14 in place of thereceiver 13 ofFig. 10 . Note that the other components are the same as those inFig. 10 . - The
receiver 13a is a refrigerant storage container that stores excess refrigerant caused during an operation. Thereceiver 13a is provided in parallel with themain circuit 30 on an outlet side of thecondenser 3. In other words, thereceiver 13a is provided in parallel with a pipe between a portion where an upstream end of thesuction bypass 8 meets themain circuit 30 and the outlet of thecondenser 3. - The
check valve 14 prevents refrigerant from flowing from amain expansion valve 4 side into thereceiver 13a. In some cases, frost forms on theevaporator 5 during a hot-water supply operation. In such a case, a reverse defrosting operation is performed. The reverse defrosting operation is an operation of removing frost forming on theevaporator 5 by switching the four-way valve 2 in directions indicated by dotted lines inFig. 11 to supply high-temperature high-pressure gas refrigerant discharged from thecompressor 1 to theevaporator 5. Thecheck valve 14 prevents refrigerant from flowing into thereceiver 13a during the reverse defrosting operation. - Next, the action of a refrigeration cycle of
Modification 1 of the refrigeration cycle apparatus according toEmbodiment 4 will be described with reference toFig. 11 . Note that a normal hot-water supply operation is the same as that inEmbodiment 1, and only a negative pressure prevention operation will be described. During the negative pressure prevention operation, the fact that themain expansion valve 4 is substantially closed is the same as that inEmbodiment 1. - In a negative pressure prevention operation in
Modification 1, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure refrigerant discharged from thecompressor 1 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the dischargedgas bypass 6 and is reduced in pressure by the dischargedgas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it is bypassed to the suction side of thecompressor 1. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3 via the four-way valve 2. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. - The high-pressure refrigerant having flowed out of the
condenser 3 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into thesuction bypass 8 via themain circuit 30, and refrigerant that is to flow through the other flow path is condensed and stored in thereceiver 13a. The high-pressure refrigerant having flowed into thesuction bypass 8 is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant. A flow of the high-temperature low-pressure gas that has been reduced in pressure by the dischargedgas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by thesuction bypass valve 9 combine to form a flow of low-temperature low-pressure gas refrigerant, and the flow is sucked into thecompressor 1 again. - Note that, since the
main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. In the negative pressure prevention operation, theevaporator 5 is not used, and the necessary amount of refrigerant is thus smaller than that in a normal hot-water supply operation, thereby causing excess refrigerant. InModification 1, however, excess refrigerant can be stored in thereceiver 13a. - As described above, in
Modification 1 of the refrigeration cycle apparatus according toEmbodiment 4, thereceiver 13a is provided in parallel with themain circuit 30 on the outlet side of thecondenser 3. This enables excess refrigerant to be stored in thereceiver 13a even when refrigerant at the outlet of thecondenser 3 is in a two-phase state. Thus, during a negative pressure prevention operation in which excess refrigerant is caused, an operation in which liquid flows back to the suction side of thecompressor 1 is prevented, thereby enabling a highly reliable negative pressure prevention operation to continue. -
Fig. 12 is a refrigerant circuit diagram of a refrigeration cycleapparatus illustrating Modification 2 of the refrigeration cycle apparatus according toEmbodiment 4 of the present invention. - As illustrated in
Fig. 12 , a refrigerant circuit ofModification 2 of the refrigeration cycle apparatus according toEmbodiment 4 includes anaccumulator 15 in place of thereceiver 13 ofFig. 10 . Note that the other components are the same as those inFig. 10 . - The
accumulator 15 is provided on the suction side of thecompressor 1 and is a refrigerant storage container that stores excess refrigerant caused during an operation. - Next, the action of a refrigeration cycle of
Modification 2 of the refrigeration cycle apparatus according toEmbodiment 4 will be described with reference toFig. 12 . Note that a normal hot-water supply operation is the same as that inEmbodiment 1, and only a negative pressure prevention operation will be described. - In a negative pressure prevention operation in
Modification 2, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure refrigerant discharged from thecompressor 1 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into the dischargedgas bypass 6 and is reduced in pressure by the dischargedgas bypass valve 7 to turn into high-temperature low-pressure gas refrigerant, and it is bypassed to the suction side of thecompressor 1. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3 via the four-way valve 2. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. - The high-pressure refrigerant having flowed out of the
condenser 3 flows into thesuction bypass 8, and the high-pressure refrigerant having flowed into thesuction bypass 8 is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure two-phase gas-liquid refrigerant. A flow of the high-temperature low-pressure gas that has been reduced in pressure by the dischargedgas bypass valve 7 and a flow of the low-temperature low-pressure two-phase gas-liquid refrigerant that has been reduced in pressure and expanded by thesuction bypass valve 9 combine to form a flow of low-temperature low-pressure refrigerant, and the flow is sucked into thecompressor 1 again via theaccumulator 15. - Note that, since the
main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. In the negative pressure prevention operation, theevaporator 5 is not used, and the necessary amount of refrigerant is thus smaller than that in a normal hot-water supply operation, thereby causing excess refrigerant. InModification 2, however, excess refrigerant can be stored in theaccumulator 15. - As described above, in
Modification 2 of the refrigeration cycle apparatus according toEmbodiment 4, theaccumulator 15 is provided on the suction side of thecompressor 1, thereby enabling excess refrigerant to be stored in theaccumulator 15 during a negative pressure prevention operation in which excess refrigerant is caused. This prevents an operation in which liquid flows back to the suction side of thecompressor 1, thereby enabling a highly reliable negative pressure prevention operation to continue. - In
Embodiments 1 to 4 described above, part of refrigerant discharged from thecompressor 1 toward thecondenser 3 is caused to flow into the dischargedgas bypass 6 so that it is diverted from themain circuit 30, and the diverted refrigerant is caused to flow back to the suction side of thecompressor 1. Then, in causing the diverted refrigerant to flow back to the suction side of thecompressor 1, a flow of the diverted refrigerant is combined with a flow of refrigerant flowing through thesuction bypass 8 on a downstream side of thesuction bypass valve 9 and then caused to flow back. In contrast to this, inEmbodiment 5, in causing diverted refrigerant that has been diverted from themain circuit 30 to flow back to the suction side of thecompressor 1, a flow of the diverted refrigerant is combined with a flow of refrigerant that is to flow through thesuction bypass 8 on an upstream side of thesuction bypass valve 9 and then caused to flow back. -
Fig. 13 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 5 of the present invention and illustrates a state provided while a hot-water supply operation of raising the temperature of water on a load side is being performed. Furthermore,Fig. 14 is a P-h diagram illustrating an action state in an operation inFig. 13 . - In
Embodiment 5, the dischargedgas bypass 6 and the dischargedgas bypass valve 7 are removed from the structure inEmbodiment 1 illustrated inFig. 1 , whereas acondenser bypass 16 that bypasses thecondenser 3 and acondenser bypass valve 17 that regulates a flow rate in thecondenser bypass 16 are included. Abypass 41 inEmbodiment 5 includes thecondenser bypass 16 and thesuction bypass 8, and is a circuit that combines a flow of refrigerant having flowed out of the condenser bypass 16 (part of refrigerant discharged from the compressor 1) and a flow of refrigerant having flowed out of thecondenser 3 into a combined flow to allow the combined flow to flow into the suction side of thecompressor 1 via thesuction bypass 8. In thebypass 41, thesuction bypass valve 9 constitutes the negative pressure regulating valve according to the present invention. - The
condenser bypass 16 bypasses part of discharged refrigerant discharged from thecompressor 1 to the outlet side of thecondenser 3. - The
condenser bypass valve 17 regulates a bypass flow rate of discharged gas to be passed through thecondenser bypass 16. - Next, the action of a refrigeration cycle of the refrigeration cycle apparatus according to
Embodiment 5 will be described with reference toFig. 13 . Note that, during a normal hot-water supply operation, thecondenser bypass valve 17 and thesuction bypass valve 9 are fully closed, and refrigerant does not flow through thecondenser bypass 16 and thesuction bypass 8. Hence, the action of a refrigeration cycle during a normal hot-water supply operation inEmbodiment 5 is the same as that inEmbodiment 1. Thus, only a negative pressure prevention operation will be described. During the negative pressure prevention operation, the fact that themain expansion valve 4 is substantially closed is the same as that inEmbodiment 1. - Next, an action in a negative pressure prevention operation will be described with reference to the refrigerant circuit diagram of
Fig. 13 and the P-h diagram ofFig. 14 . InFig. 14 , [1] to [5] respectively indicate refrigerant states at positions of [1] to [5] inFig. 13 . - In a negative pressure prevention operation in the refrigeration cycle apparatus according to
Embodiment 5, refrigerant ([1]) being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas ([2]), and discharged. The high-temperature high-pressure gas refrigerant discharged from thecompressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into thecondenser bypass 16 and is reduced in pressure ([3]) by thecondenser bypass valve 17, and then it flows out of thecondenser bypass 16. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant ([4]). - A flow of the high-temperature high-pressure gas refrigerant having flowed out of the
condenser bypass 16 and a flow of the high-pressure liquid refrigerant having flowed out of thecondenser 3 combine to form a flow of high-pressure high-quality two-phase refrigerant ([5]). The two-phase refrigerant flows into thesuction bypass 8 and is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure gas refrigerant ([1]), and the low-temperature low-pressure gas refrigerant is sucked into thecompressor 1 again. Note that, since themain expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. - In
Embodiments 1 to 4 described above, a compressor suction pressure is controlled by the dischargedgas bypass valve 7. In contrast to this, with respect to the flow of refrigerant inEmbodiment 5, as illustrated inFig. 14 , a flow of refrigerant ([3]) having flowed out of thecondenser bypass 16 and a flow of refrigerant ([4]) having flowed out of thecondenser 3 combine to form a combined flow, and refrigerant in the combined flow is reduced in pressure by thesuction bypass valve 9 and sucked into thecompressor 1. Thus, inEmbodiment 5, a compressor suction pressure is controlled by thesuction bypass valve 9. -
Fig. 15 is a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 5 of the present invention. - As illustrated in
Fig. 15 , the refrigeration cycle apparatus according toEmbodiment 5 differs from that illustrated inFig. 4 in that thecontroller 20 is connected in such a manner as to be able to control thecondenser bypass valve 17 in place of the dischargedgas bypass valve 7 in the system configuration inEmbodiment 1 illustrated inFig. 4 . Furthermore, as functional components of thecontroller 20, thecontroller 20 includes a negative pressureprevention control unit 20A and a superheatdegree control unit 20B. The negative pressureprevention control unit 20A performs a negative pressure prevention operation of controlling the opening degree of thesuction bypass valve 9 to prevent a suction pressure of thecompressor 1 from becoming negative. The superheatdegree control unit 20B regulates the opening degree of thecondenser bypass valve 17 so that a degree of superheat of gas to be sucked into thecompressor 1 becomes a setting value set in advance. The negative pressureprevention control unit 20A and the superheatdegree control unit 20B are functionally configured by the CPU and the control program. Configurations other than these are the same as those illustrated inFig. 4 . -
Fig. 16 is a flowchart illustrating a control procedure of a negative pressure prevention operation in the refrigeration cycle apparatus according toEmbodiment 5 of the present invention. In comparison with the flowchart inEmbodiment 1 illustrated inFig. 5 described above, the flowchart inEmbodiment 5 illustrated inFig. 16 differs from that inEmbodiment 1 in the following respects. That is, control of the opening degree of the dischargedgas bypass valve 7 in steps S6 and S7 inFig. 5 is replaced with control of the opening degree of thesuction bypass valve 9 in steps S6a and S7a inFig. 16 . Furthermore, control of the opening degree of thesuction bypass valve 9 in steps S11 and S12 inFig. 5 is replaced with control of the opening degree of thecondenser bypass valve 17 inFig. 16 . The other steps are the same as those in the control flowchart ofFig. 5 . A description will be given below with emphasis on a respect in which control of the negative pressure prevention operation inEmbodiment 5 differs from that inEmbodiment 1. - In
Embodiment 5, as a result of a comparison of a compressor suction pressure Ps and a settingvalue 2 set in advance in step S5, when the compressor suction pressure Ps is lower than the settingvalue 2, the opening degree of thesuction bypass valve 9 is increased (S6a). Thus, the compressor suction pressure Ps rises and approaches the settingvalue 2. On the other hand, when the compressor suction pressure Ps is higher than the settingvalue 2, the opening degree of thesuction bypass valve 9 is reduced (S7a). Thus, the compressor suction pressure Ps falls and approaches the settingvalue 2. - Furthermore, in
Embodiment 5, as a result of a comparison of a compressor suction superheat degree SHs and a settingvalue 3 that has been set in advance as a target value of a compressor suction superheat degree in step S10, when the compressor suction superheat degree SHs is lower than the settingvalue 3, thecontroller 20 increases the opening degree of the condenser bypass valve 17 (S11a). Thus, the compressor suction superheat degree SHs rises and approaches the settingvalue 3. On the other hand, when the compressor suction superheat degree SHs is higher than the settingvalue 3, the opening degree of thecondenser bypass valve 17 is reduced (S12a). Thus, the compressor suction superheat degree SHs falls and approaches the settingvalue 3. Then, after the process of S11a or S12a, thecontroller 20 returns to S5 and repeatedly performs control so that the compressor suction pressure Ps and the compressor suction superheat degree SHs respectively become equal to thecorresponding setting value 2 and settingvalue 3. - As described above, in controlling a compressor suction pressure and a compressor suction superheat degree, the refrigeration cycle apparatus according to
Embodiment 5 differs from that inEmbodiment 1 in bypass valves to be controlled, but can produce the same effect as that inEmbodiment 1. That is, when an operation state in which an outdoor air temperature is low and a compressor suction pressure is close to a negative pressure is entered, a hot-water supply operation is continued with themain expansion valve 4 being fully closed without evaporation of refrigerant in theevaporator 5. Then, the compressor suction pressure is controlled by using the opening degree of thesuction bypass valve 9, and a suction superheat degree of thecompressor 1 is also controlled by using the opening degree of thecondenser bypass valve 17. This prevents the compressor suction pressure from becoming negative and also enables the hot-water supply operation to continue with the compressor suction superheat degree being appropriate. Thus, even when an outdoor air temperature falls, a disadvantage, such as a malfunction due to suction of air, can be avoided. Furthermore, in a water heater, a hot-water supply operation of raising the temperature of water does not have to be stopped even under low outdoor air temperature conditions, thus making it possible to prevent water pipes from freezing, for example. -
Embodiment 6 corresponds to, so to speak, a combination ofEmbodiment 5 andEmbodiment 4 in which thereceiver 13 is included. A description will be given below with emphasis on a respect in whichEmbodiment 6 differs fromEmbodiment 5. -
Fig. 17 is a refrigerant circuit diagram of the refrigeration cycle apparatus according toEmbodiment 6 of the present invention. - As illustrated in
Fig. 17 , a system configuration diagram of the refrigeration cycle apparatus according toEmbodiment 6 includes thereceiver 13. Note that the other components are the same as those inEmbodiment 5 illustrated inFig. 13 . - The
receiver 13 is disposed on a pipe connecting thecondenser 3 and thesuction bypass valve 9 and stores excess refrigerant caused during an operation. - Next, the action of a refrigeration cycle according to
Embodiment 6 will be described with reference toFig. 17 . Note that a normal hot-water supply operation is the same as that inEmbodiment 1, and thus a description thereof is omitted. Only a negative pressure prevention operation will be described. - Refrigerant being in a low-temperature low-pressure gas state is sucked into the
compressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure gas refrigerant discharged from thecompressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into thecondenser bypass 16 and is reduced in pressure by thecondenser bypass valve 17, and then it flows out of thecondenser bypass 16. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant and flows into thereceiver 13. A flow of the high-temperature high-pressure gas refrigerant having flowed out of thecondenser bypass 16 and a flow of the high-pressure liquid refrigerant having flowed out of thereceiver 13 combine to form a flow of high-pressure high-quality two-phase refrigerant, and the flow flows into thesuction bypass 8. The two-phase refrigerant having flowed into thesuction bypass 8 is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure gas refrigerant, and the low-temperature low-pressure gas refrigerant is sucked into thecompressor 1 again. - Note that, since the
main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. In the negative pressure prevention operation, theevaporator 5 is not used, and the necessary amount of refrigerant is thus smaller than that in a normal hot-water supply operation, thereby causing excess refrigerant. InEmbodiment 6, however, excess refrigerant is stored in thereceiver 13. - As described above, the refrigeration cycle apparatus according to
Embodiment 6 produces the same effect as that inEmbodiment 5 and also produces the following effect. That is, excess refrigerant can be stored in thereceiver 13 during a negative pressure prevention operation, thereby preventing an operation in which liquid flows back to the suction side of thecompressor 1 and enabling a highly reliable negative pressure prevention operation to continue. - Although
Embodiment 6 presents the structure including a refrigerant storage container (thereceiver 13 herein), the disposition of the refrigerant storage container is not limited to the disposition illustrated inFig. 17 , and modifications can be made as described in the followingModifications -
Fig. 18 is a refrigerant circuit diagram ofModification 1 of the refrigeration cycle apparatus according toEmbodiment 6 of the present invention. - As illustrated in
Fig. 18 , a refrigerant circuit ofModification 1 of the refrigeration cycle apparatus according toEmbodiment 6 includes thereceiver 13a and thecheck valve 14 in place of thereceiver 13 ofFig. 17 . The other components are the same as those inFig. 17 . - The
receiver 13a is a refrigerant storage container that stores excess refrigerant caused during an operation. Thereceiver 13a is provided in parallel with themain circuit 30 on the outlet side of thecondenser 3. In other words, thereceiver 13a is provided in parallel with a pipe between a portion where a downstream end of thecondenser bypass 16 meets themain circuit 30 and the outlet of thecondenser 3. - The
check valve 14 prevents refrigerant from flowing from themain expansion valve 4 side into thereceiver 13a. In some cases, frost forms on theevaporator 5 during a hot-water supply operation. In such a case, a reverse defrosting operation is performed. The reverse defrosting operation is an operation of removing frost forming on theevaporator 5 by switching the four-way valve 2 in directions indicated by dotted lines inFig. 18 to supply high-temperature high-pressure gas refrigerant discharged from thecompressor 1 to theevaporator 5. Thecheck valve 14 prevents the inflow of refrigerant during the reverse defrosting operation. - Next, the action of a refrigeration cycle of
Modification 1 of the refrigeration cycle apparatus according toEmbodiment 6 will be described with reference toFig. 18 . Note that a normal hot-water supply operation is the same as that inEmbodiment 5, and thus a description thereof is omitted. Only a negative pressure prevention operation will be described. During the negative pressure prevention operation, the fact that themain expansion valve 4 is substantially closed is the same as that inEmbodiment 5. - In a negative pressure prevention operation in
Modification 1, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure gas refrigerant discharged from thecompressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into thecondenser bypass 16 and is reduced in pressure by thecondenser bypass valve 17, and then it flows out of thecondenser bypass 16. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. - The high-pressure refrigerant having flowed out of the
condenser 3 is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into themain circuit 30, and refrigerant that is to flow through the other flow path is condensed and stored in thereceiver 13a. A flow of the high-pressure refrigerant having flowed into themain circuit 30 combines with a flow of the high-temperature high-pressure gas refrigerant having flowed out of thecondenser bypass 16 to form a flow of high-pressure high-quality two-phase refrigerant. The two-phase refrigerant flows into thesuction bypass 8 and is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure gas refrigerant, and the low-temperature low-pressure gas refrigerant is sucked into thecompressor 1 again. - Note that, since the
main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. In the negative pressure prevention operation, theevaporator 5 is not used, and the necessary amount of refrigerant is thus smaller than that in a normal hot-water supply operation, thereby causing excess refrigerant. InModification 1, however, excess refrigerant is stored in thereceiver 13a. - As described above, in
Modification 1 of the refrigeration cycle apparatus according toEmbodiment 6, thereceiver 13a is provided in parallel with themain circuit 30 on the outlet side of thecondenser 3. This enables excess refrigerant to be stored in thereceiver 13a even when refrigerant at the outlet of thecondenser 3 is in a two-phase state. Thus, during a negative pressure prevention operation in which excess refrigerant is caused, an operation in which liquid flows back to the suction side of thecompressor 1 is prevented, thereby enabling a highly reliable negative pressure prevention operation to continue. -
Fig. 19 is a refrigerant circuit diagram ofModification 2 of the refrigeration cycle apparatus according toEmbodiment 6 of the present invention. - As illustrated in
Fig. 19 , a refrigerant circuit ofModification 2 of the refrigeration cycle apparatus according toEmbodiment 6 includes theaccumulator 15 in place of thereceiver 13 ofFig. 17 . Note that the other components are the same as those inFig. 17 . - The
accumulator 15 is provided on the suction side of thecompressor 1 and stores excess refrigerant caused during an operation. - Next, the action of
Modification 2 of the refrigeration cycle apparatus according toEmbodiment 6 will be described with reference toFig. 19 . Note that a normal hot-water supply operation is the same as that inEmbodiment 1, and thus a description thereof is omitted. Only a negative pressure prevention operation will be described. - In a negative pressure prevention operation in
Modification 2, refrigerant being in a low-temperature low-pressure gas state is sucked into thecompressor 1, compressed to turn into high-temperature high-pressure gas, and discharged. The high-temperature high-pressure gas refrigerant discharged from thecompressor 1 passes through the four-way valve 2 and then is divided to flow through two flow paths. Refrigerant that is to flow through one flow path flows into thecondenser bypass 16 and is reduced in pressure by thecondenser bypass valve 17, and then it flows out of thecondenser bypass 16. Divided high-temperature high-pressure gas refrigerant that is to flow through the other flow path flows into thecondenser 3. The high-temperature high-pressure gas refrigerant having flowed into thecondenser 3 transfers heat to water serving as a medium to be subjected to heat exchange to turn into high-pressure liquid refrigerant. A flow of the high-temperature high-pressure gas refrigerant having flowed out of thecondenser bypass 16 and a flow of the high-pressure liquid refrigerant having flowed out of thecondenser 3 combine to form a flow of high-pressure high-quality two-phase refrigerant, and the flow flows into thesuction bypass 8. The two-phase refrigerant having flowed into thesuction bypass 8 is reduced in pressure and expanded by thesuction bypass valve 9 to turn into low-temperature low-pressure refrigerant, and the low-temperature low-pressure refrigerant is sucked into thecompressor 1 again via theaccumulator 15. - Note that, since the
main expansion valve 4 is substantially closed during the negative pressure prevention operation, little low-pressure two-phase refrigerant flows into theevaporator 5, and evaporation of refrigerant caused by heat exchange with outdoor air does not occur. - As described above, in
Modification 2 of the refrigeration cycle apparatus according toEmbodiment 6, theaccumulator 15 is provided on the suction side of thecompressor 1, thereby enabling excess refrigerant to be stored in theaccumulator 15 during a negative pressure prevention operation in which excess refrigerant is caused. This prevents an operation in which liquid flows back to the suction side of thecompressor 1, thereby enabling a highly reliable negative pressure prevention operation to continue. - In Embodiments and Modifications described above, as refrigerant, a single refrigerant of HFO-1234yf, a single refrigerant of HFO-1234ze, or a refrigerant mixture of HFO-1234yf or HFO-1234ze and R32 is used. Note that refrigerant may be any refrigerant that has a higher boiling point than R407C. Furthermore, it is desirable that refrigerant be refrigerant whose global warming potential is lower than that of R407C.
- In each Embodiment described above, the case where the refrigeration cycle apparatus is used for a heat pump water heater is described, whereas the refrigeration cycle apparatus can also be used for an air-conditioning apparatus, for example.
- 1
compressor 2 four-way valve 3condenser 4main expansion valve 5evaporator 6 dischargedgas bypass 7 dischargedgas bypass valve 8suction bypass 9suction bypass valve 10 two-way valve 11ejector 11a nozzle11b expansion 11dsection 11c diffuserrefrigerant suction section 12suction pipe 13receiver 13a receivercheck valve 15accumulator 16condenser bypass 17condenser bypass valve 20controller 20A negative pressureprevention control unit 20B superheatdegree control unit 20a negative pressureprevention control unit 20b superheatdegree control unit 21 compressorsuction pressure sensor 22 compressorsuction temperature sensor 30main circuit 40bypass 41 bypass
Claims (14)
- A refrigeration cycle apparatus comprising:a main circuit (30) in which a compressor (1), a condenser (3), a main expansion valve (4), and an evaporator (5) are connected in a circle, the main circuit (30) being configured to circulate refrigerant having a higher boiling point than R407C therethrough;a bypass (40, 41) configured to combine a flow of part of refrigerant discharged from the compressor (1) and a flow of refrigerant flowing out of the condenser (3) into a combined flow, and allowing the combined flow to flow into a suction side of the compressor (1);a negative pressure regulating valve (7, 9) configured to regulate a flow rate in the bypass (40, 41); a compressor suction pressure
sensor (21) at a suction side of the compressor; anda negative pressure prevention control unit (20a, 20A) configured to perform a negative pressure prevention operation of controlling the negative pressure regulating valve (7, 9) to prevent the suction pressure of the compressor (1) from becoming smaller than atmospheric pressure, wherein the bypass includes a discharged gas bypass (6) configured to bypass part of refrigerant discharged from the compressor (1) to a suction side, and a suction bypass (8) configured to combine a flow of refrigerant flowing out of the condenser (3) into a flow in the discharged gas bypass (6), and allowing the flow to flow into the suction side of the compressor (1),whereinthe negative pressure regulating valve (7) is a discharged gas bypass valve (7) configured to regulate a flow rate in the discharged gas bypass (6), and whereinduring the negative pressure prevention operation, the negative pressure prevention control unit (20a, 20A) is configured to close the main expansion valve (4) and also regulate an opening degree of the discharged gas bypass valve (7) so that the suction pressure becomes a second setting value set in advance. - The refrigeration cycle apparatus of claim 1, wherein the main circuit (30) further includes a four-way valve (2) configured to switch between directions in which refrigerant discharged from the compressor (1) flows.
- The refrigeration cycle apparatus of claim 2, further comprising a two-way valve (10) provided between the four-way valve (2) and the evaporator (5).
- The refrigeration cycle apparatus of claim 3, wherein the negative pressure prevention control unit (20a, 20A) is configured to close the two-way valve (10) during the negative pressure prevention operation.
- The refrigeration cycle apparatus of claim 2, further comprising:in the bypass (40, 41), an ejector (11) provided in a discharged gas bypass (6) configured to bypass part of refrigerant discharged from the compressor (1) to the suction side; anda suction circuit configured to allow a suction section of the ejector (11) to suck refrigerant between the evaporator (5) and the four-way valve (2).
- A refrigeration cycle apparatus comprising:A main circuit (30) in which a compressor (1), a condenser (3), a main expansion valve (4), an evaporator (5), a four-way valve (2) being configured to switch between directions in which refrigerant discharged from the compressor (1) flows, and a two-way valve (10) being provided between the four-way valve (2) and the evaporator (5), are connected in a circle, and through which refrigerant having a higher boiling point than R407C circulates;a bypass (40, 41) configured to combine a flow of part of refrigerant discharged from the compressor (1) and a flow of refrigerant flowing out of the condenser (3, 16) into a combined flow, and allowing the combined flow to flow into a suction side of the compressor (1);a negative pressure regulating valve (7, 9) configured to regulate a flow rate in the bypass (40, 41); a compressor suction pressure sensor (21) at a suction side of the compressor; anda negative pressure prevention control unit (20a, 20A);wherein, during heating operation, the four-way valve (2) is configured to route the refrigerant discharged from the compressor (1) to the condenser (3) and the negative pressure prevention control unit (20a, 20A) is configured to perform a negative pressure prevention operation of controlling the negative pressure regulating valve (7, 9) to prevent the suction pressure of the compressor (1) from becoming smaller than atmospheric pressure, and to close the two-way valve (10) during the negative pressure prevention operation.
- The refrigeration cycle apparatus of claim 6, wherein the bypass (40) includes
a discharged gas bypass (6) configured to bypass part of refrigerant discharged from the compressor (1) to a suction side, and a suction bypass (8) configured to combine a flow of refrigerant flowing out of the condenser (3) into a flow in the discharged gas bypass (6), and allowing the flow to flow into the suction side of the compressor (1), and wherein the negative pressure regulating valve (7) is a discharged gas bypass valve (7) configured to regulate a flow rate in the discharged gas bypass (6). - The refrigeration cycle apparatus of claim 7,
wherein, when the suction pressure detected by the pressure sensor (21) is below a first setting value set in advance, the negative pressure prevention control unit (20a) is configured to start the negative pressure prevention operation to control the discharged gas bypass valve (7). - The refrigeration cycle apparatus of claim 7 or 8, wherein, during the negative pressure prevention operation, the negative pressure prevention control unit (20a) is configured to regulate an opening degree of the discharged gas bypass valve (7) so that the suction pressure becomes a second setting value set in advance.
- The refrigeration cycle apparatus of claim 8 or 9, further comprising a suction bypass valve (9) configured to regulate a flow rate in the suction bypass (8) to control a degree of superheat of gas to be sucked into the compressor (1).
- The refrigeration cycle apparatus of claim 10, further comprising a superheat degree control unit (20b) configured to regulate an opening degree of the suction bypass valve (9) so that a degree of superheat of gas to be sucked into the compressor (1) becomes a third setting value set in advance.
- The refrigeration cycle apparatus of any one of claims 1 to 10, further comprising a receiver (13) provided on an outlet side of the condenser (3).
- The refrigeration cycle apparatus of any one of claims 1 to 10, further comprising a receiver (13) provided in parallel with the main circuit (30) on an outlet side of the condenser (3).
- The refrigeration cycle apparatus of any one of claims 1 to 10, further comprising an accumulator (15) provided on the suction side of the compressor (1).
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2015/051068 WO2016113899A1 (en) | 2015-01-16 | 2015-01-16 | Refrigeration cycle device |
Publications (3)
Publication Number | Publication Date |
---|---|
EP3246637A1 EP3246637A1 (en) | 2017-11-22 |
EP3246637A4 EP3246637A4 (en) | 2018-12-26 |
EP3246637B1 true EP3246637B1 (en) | 2021-06-16 |
Family
ID=56405460
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP15877851.4A Active EP3246637B1 (en) | 2015-01-16 | 2015-01-16 | Refrigeration cycle device |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP3246637B1 (en) |
JP (1) | JP6275283B2 (en) |
WO (1) | WO2016113899A1 (en) |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3524904A1 (en) * | 2018-02-06 | 2019-08-14 | Carrier Corporation | Hot gas bypass energy recovery |
JP7303413B2 (en) * | 2018-09-28 | 2023-07-05 | ダイキン工業株式会社 | heat pump equipment |
CN109140840A (en) * | 2018-11-02 | 2019-01-04 | 西安交通大学 | A kind of air conditioner and control method using suction and discharge bypass line |
CN109373636B (en) * | 2018-11-09 | 2023-07-04 | 珠海格力电器股份有限公司 | System and method for preventing liquid impact |
KR20200097127A (en) | 2019-02-07 | 2020-08-18 | 삼성전자주식회사 | Air conditioner system comprising refrigerant cycle circuitry for oil flow blocking |
US20220205662A1 (en) * | 2019-07-25 | 2022-06-30 | Mitsubishi Electric Corporation | Air-conditioning apparatus |
CN110736204B (en) * | 2019-09-25 | 2021-11-23 | 青岛海尔空调器有限总公司 | Control method and control device for defrosting of air conditioner and air conditioner |
JP7298580B2 (en) * | 2019-11-22 | 2023-06-27 | 株式会社デンソー | refrigeration cycle equipment |
WO2021100409A1 (en) * | 2019-11-22 | 2021-05-27 | 株式会社デンソー | Refrigeration cycle device |
WO2021166494A1 (en) * | 2020-02-20 | 2021-08-26 | 株式会社デンソー | Refrigeration cycle device |
CN111536722A (en) * | 2020-05-26 | 2020-08-14 | 广东省现代农业装备研究所 | Defrosting method and device for supercooling refrigerant of main path of refrigeration cycle |
CN113639415B (en) * | 2021-07-23 | 2023-05-26 | 青岛海尔空调电子有限公司 | Method and device for defrosting air conditioner and air conditioner |
JP2023075844A (en) * | 2021-11-19 | 2023-05-31 | サンデン株式会社 | vehicle air conditioner |
Family Cites Families (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2517071B2 (en) * | 1988-08-17 | 1996-07-24 | 日本電信電話株式会社 | Cooling device and its control method |
DE4433712A1 (en) * | 1994-09-21 | 1996-03-28 | Bosch Siemens Hausgeraete | Refrigerated cabinets with at least two compartments of different temperatures |
JPH1114165A (en) * | 1997-06-25 | 1999-01-22 | Mitsubishi Heavy Ind Ltd | Air-conditioner |
JP2001280669A (en) * | 2000-03-30 | 2001-10-10 | Mitsubishi Electric Corp | Refrigerating cycle device |
US6711906B2 (en) * | 2001-04-20 | 2004-03-30 | Hankison International | Variable evaporator control for a gas dryer |
KR100471723B1 (en) * | 2002-05-17 | 2005-03-08 | 삼성전자주식회사 | Air conditioner and control method thereof |
US7331189B2 (en) * | 2004-11-24 | 2008-02-19 | Hoshizaki Denki Kabushiki Kaisha | Cooling device |
JP2009041845A (en) * | 2007-08-09 | 2009-02-26 | Panasonic Corp | Operation control method of multi-room type air conditioner |
JP4597180B2 (en) * | 2007-11-06 | 2010-12-15 | 本田技研工業株式会社 | Vehicle air conditioning system |
CN101910750A (en) * | 2008-01-17 | 2010-12-08 | 开利公司 | Capacity modulation of refrigerant vapor compression system |
JP5014271B2 (en) * | 2008-06-24 | 2012-08-29 | 三菱電機株式会社 | Refrigeration cycle equipment |
US9453669B2 (en) * | 2009-12-08 | 2016-09-27 | Thermo King Corporation | Method of controlling inlet pressure of a refrigerant compressor |
JP5605191B2 (en) * | 2010-12-01 | 2014-10-15 | 東京電力株式会社 | heat pump |
WO2012127834A1 (en) * | 2011-03-18 | 2012-09-27 | パナソニック株式会社 | Refrigeration cycle device |
JP5754627B2 (en) * | 2011-04-25 | 2015-07-29 | 株式会社大気社 | Fluid cooling method and fluid cooling device |
JP2013184592A (en) * | 2012-03-08 | 2013-09-19 | Denso Corp | Refrigerating cycle device for air-conditioning vehicle and for temperature-conditioning parts constituting vehicle |
JP5972024B2 (en) * | 2012-04-25 | 2016-08-17 | 三菱電機株式会社 | Refrigeration equipment |
CN104254743B (en) * | 2012-04-27 | 2016-04-27 | 三菱电机株式会社 | Conditioner |
CN104937352B (en) * | 2013-01-21 | 2017-08-08 | 东芝开利株式会社 | Binary refrigeration cycle device |
JP5962596B2 (en) * | 2013-06-18 | 2016-08-03 | 株式会社デンソー | Ejector refrigeration cycle |
-
2015
- 2015-01-16 EP EP15877851.4A patent/EP3246637B1/en active Active
- 2015-01-16 JP JP2016569194A patent/JP6275283B2/en active Active
- 2015-01-16 WO PCT/JP2015/051068 patent/WO2016113899A1/en active Application Filing
Non-Patent Citations (1)
Title |
---|
None * |
Also Published As
Publication number | Publication date |
---|---|
EP3246637A1 (en) | 2017-11-22 |
JPWO2016113899A1 (en) | 2017-07-13 |
WO2016113899A1 (en) | 2016-07-21 |
JP6275283B2 (en) | 2018-02-07 |
EP3246637A4 (en) | 2018-12-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3246637B1 (en) | Refrigeration cycle device | |
US10247454B2 (en) | Refrigerating apparatus | |
US10208987B2 (en) | Heat pump with an auxiliary heat exchanger for compressor discharge temperature control | |
US9068766B2 (en) | Air-conditioning and hot water supply combination system | |
EP2068096B1 (en) | Refrigeration device | |
US11268743B2 (en) | Air-conditioning apparatus having heating-defrosting operation mode | |
US10845095B2 (en) | Air-conditioning apparatus | |
EP3205954B1 (en) | Refrigeration cycle device | |
EP3109566B1 (en) | Air conditioning device | |
US10161647B2 (en) | Air-conditioning apparatus | |
US11022354B2 (en) | Air conditioner | |
EP2770276B1 (en) | Heat pump | |
EP3859245A1 (en) | Heat pump device | |
EP3093586A1 (en) | Air conditioning device | |
EP3211350A1 (en) | Refrigeration cycle device, and hot water heating device provided with the same | |
JP6463464B2 (en) | Refrigeration cycle equipment | |
EP3236168A1 (en) | Air conditioning device | |
EP3351870B1 (en) | Refrigerant circuit system and control method | |
EP3220078A1 (en) | Refrigeration cycle device and hot water heating device provided with the same | |
US11015851B2 (en) | Refrigeration cycle device | |
JP6588645B2 (en) | Refrigeration cycle equipment | |
WO2020202519A1 (en) | Refrigeration cycle device | |
EP3217118A1 (en) | Heat pump apparatus |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE |
|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE |
|
17P | Request for examination filed |
Effective date: 20170608 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
AX | Request for extension of the european patent |
Extension state: BA ME |
|
DAX | Request for extension of the european patent (deleted) | ||
RIC1 | Information provided on ipc code assigned before grant |
Ipc: F25B 47/02 20060101ALI20180814BHEP Ipc: F25B 41/06 20060101ALI20180814BHEP Ipc: F25B 29/00 20060101ALI20180814BHEP Ipc: F25B 1/00 20060101AFI20180814BHEP Ipc: F25B 41/04 20060101ALI20180814BHEP Ipc: F25B 13/00 20060101ALI20180814BHEP Ipc: F25B 49/02 20060101ALI20180814BHEP |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 20181122 |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: F25B 1/00 20060101AFI20181116BHEP Ipc: F25B 41/04 20060101ALI20181116BHEP Ipc: F25B 13/00 20060101ALI20181116BHEP Ipc: F25B 29/00 20060101ALI20181116BHEP Ipc: F25B 49/02 20060101ALI20181116BHEP Ipc: F25B 41/06 20060101ALI20181116BHEP Ipc: F25B 47/02 20060101ALI20181116BHEP |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: EXAMINATION IS IN PROGRESS |
|
17Q | First examination report despatched |
Effective date: 20200402 |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: GRANT OF PATENT IS INTENDED |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: F25B 1/00 20060101AFI20210107BHEP Ipc: F25B 47/02 20060101ALI20210107BHEP Ipc: F25B 29/00 20060101ALI20210107BHEP Ipc: F25B 13/00 20060101ALI20210107BHEP Ipc: F25B 49/02 20060101ALI20210107BHEP |
|
INTG | Intention to grant announced |
Effective date: 20210126 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE PATENT HAS BEEN GRANTED |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602015070547 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: REF Ref document number: 1402659 Country of ref document: AT Kind code of ref document: T Effective date: 20210715 |
|
REG | Reference to a national code |
Ref country code: IE Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: LT Ref legal event code: MG9D |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: HR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: BG Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210916 Ref country code: LT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: FI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: MK05 Ref document number: 1402659 Country of ref document: AT Kind code of ref document: T Effective date: 20210616 |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: MP Effective date: 20210616 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LV Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210917 Ref country code: RS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: SE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: NO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210916 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: ES Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: PT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20211018 Ref country code: NL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: RO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: CZ Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: EE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: SK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: SM Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: PL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R097 Ref document number: 602015070547 Country of ref document: DE |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
26N | No opposition filed |
Effective date: 20220317 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MC Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
REG | Reference to a national code |
Ref country code: BE Ref legal event code: MM Effective date: 20220131 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220116 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220131 Ref country code: BE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220131 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220131 Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220131 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220116 |
|
P01 | Opt-out of the competence of the unified patent court (upc) registered |
Effective date: 20230512 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20231130 Year of fee payment: 10 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R084 Ref document number: 602015070547 Country of ref document: DE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: HU Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT; INVALID AB INITIO Effective date: 20150116 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 Ref country code: CY Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20210616 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20231128 Year of fee payment: 10 |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: 746 Effective date: 20240605 |