WO2009107626A1 - 冷凍装置 - Google Patents

冷凍装置 Download PDF

Info

Publication number
WO2009107626A1
WO2009107626A1 PCT/JP2009/053347 JP2009053347W WO2009107626A1 WO 2009107626 A1 WO2009107626 A1 WO 2009107626A1 JP 2009053347 W JP2009053347 W JP 2009053347W WO 2009107626 A1 WO2009107626 A1 WO 2009107626A1
Authority
WO
WIPO (PCT)
Prior art keywords
heat exchanger
refrigerant
pipe
compression
pressure
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.)
Ceased
Application number
PCT/JP2009/053347
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
吉見　敦史
修二 藤本
岡本　昌和
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daikin Industries Ltd
Original Assignee
Daikin Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Daikin Industries Ltd filed Critical Daikin Industries Ltd
Priority to US12/919,047 priority Critical patent/US20110005270A1/en
Priority to EP09714344.0A priority patent/EP2264380B1/de
Priority to AU2009218270A priority patent/AU2009218270B2/en
Priority to CN2009801070403A priority patent/CN101960235B/zh
Publication of WO2009107626A1 publication Critical patent/WO2009107626A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
    • 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
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
    • 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
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
    • F25B2309/061—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical 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
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/021—Indoor unit or outdoor unit with auxiliary heat exchanger not forming part of the indoor or outdoor unit
    • 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
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
    • F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
    • 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—Component parts or details not otherwise provided for in this subclass
    • 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—Component parts or details not otherwise provided for in this subclass
    • F25B2400/07—Details of compressors or related parts
    • F25B2400/072—Intercoolers therefor
    • 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—Component parts or details not otherwise provided for in this subclass
    • F25B2400/13—Economisers
    • 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
    • F25B2600/17—Control issues by controlling the pressure of the condenser

Definitions

  • the present invention relates to a refrigeration apparatus, and more particularly, to a refrigeration apparatus having a refrigerant circuit configured to be capable of switching between a cooling operation and a heating operation and performing a multistage compression refrigeration cycle.
  • the refrigeration apparatus includes a compression mechanism, a heat source side heat exchanger that functions as a refrigerant radiator or evaporator, a use side heat exchanger that functions as a refrigerant evaporator or radiator, and a switching mechanism. And an intermediate heat exchanger.
  • the compression mechanism has a plurality of compression elements, and is configured to sequentially compress the refrigerant discharged from the compression element on the front stage side among the plurality of compression elements by the compression element on the rear stage side.
  • the “compression mechanism” refers to a compressor in which a plurality of compression elements are integrally incorporated, a compressor in which a single compression element is incorporated, and / or a compressor in which a plurality of compression elements are incorporated.
  • compression element on the front stage and “compression element on the rear stage” It is not only meant to include two compression elements connected in series, but a plurality of compression elements are connected in series, and the relationship between the compression elements is the above-mentioned “previous-side compression element” ”And“ compression element on the rear stage side ”.
  • the switching mechanism includes a cooling operation state in which the refrigerant is circulated in the order of the compression mechanism, the heat source side heat exchanger that functions as a refrigerant radiator, and the use side heat exchanger that functions as an evaporator of the refrigerant, and the compression mechanism, the refrigerant radiator
  • This is a mechanism for switching between a heating operation state in which the refrigerant is circulated in the order of the use side heat exchanger that functions as a refrigerant and the heat source side heat exchanger that functions as a refrigerant evaporator.
  • the intermediate heat exchanger causes the switching mechanism to function as a refrigerant cooler that is discharged from the front-stage compression element and sucked into the rear-stage compression element. It is a heat exchanger that can function as an evaporator for the refrigerant that has dissipated heat in the use side heat exchanger.
  • the refrigerant discharged from the compression element on the lower stage side of the compressor is sucked into the compression element on the rear stage side of the compressor and further compressed, the refrigerant from the compression element on the rear stage side of the compressor
  • the temperature of the discharged refrigerant becomes high.
  • the temperature difference between air or water as a heat source and the refrigerant becomes large. Since the heat dissipation loss increases, there is a problem that it is difficult to obtain high operating efficiency.
  • an intermediate heat exchanger that functions as a refrigerant cooler that is discharged from the preceding compression element and sucked into the latter compression element. Since the temperature of the refrigerant sucked into the compression element at the rear stage is lowered, the temperature of the refrigerant finally discharged from the compression mechanism can be kept low compared to the case where no intermediate heat exchanger is provided. Thereby, in the cooling operation, since the heat radiation loss in the heat source side heat exchanger functioning as a refrigerant radiator is reduced, the operation efficiency during the cooling operation can be improved.
  • the intermediate heat exchanger By bypassing the refrigerant sucked into the compression element so that it is not cooled in the intermediate heat exchanger, the intermediate heat exchanger is not used, so that the heating capacity in the use side heat exchanger can be increased during the heating operation. It can suppress that it becomes low and it can prevent the operating efficiency at the time of a heating operation falling.
  • the intermediate heat exchanger is not used during the heating operation, the intermediate heat exchanger is provided as a heat exchanger that is used only during the cooling operation. Therefore, the intermediate heat exchanger is used during the heating operation. It becomes a device that is not. Therefore, in this refrigeration apparatus, the refrigerant that has radiated heat in the use-side heat exchanger when the switching mechanism is in the cooling operation state, the intermediate heat exchanger functions as a cooler, and the switching mechanism is in the heating operation state. To function as an evaporator. For this reason, in this refrigeration apparatus, the temperature of the refrigerant discharged from the compression mechanism can be kept low during the cooling operation, and during the heating operation, the evaporation capacity of the refrigerant can be increased and intermediate heat exchange can be performed.
  • Heat dissipation from the vessel to the outside can be suppressed.
  • the heat dissipation loss in the heat source side heat exchanger that functions as a refrigerant radiator can be reduced, and the operating efficiency during the cooling operation can be improved.
  • the effective use of the intermediate heat exchanger can be achieved, and the heating capacity in the use side heat exchanger can be suppressed from being lowered, so that the operation efficiency during the heating operation is not lowered.
  • the refrigeration apparatus is the refrigeration apparatus according to the first aspect of the invention, wherein the intermediate heat exchanger has an intermediate refrigerant pipe for sucking the refrigerant discharged from the front-stage compression element into the rear-stage compression element.
  • An intermediate heat exchanger bypass pipe is connected to the intermediate refrigerant pipe so as to bypass the intermediate heat exchanger, and one end of the intermediate heat exchanger is connected to the suction side of the compression mechanism.
  • an intermediate heat exchanger return pipe for connecting between the use side heat exchanger and the heat source side heat exchanger and the other end of the intermediate heat exchanger.
  • the intermediate pressure refrigerant flowing through the intermediate refrigerant pipe can be cooled by the intermediate heat exchanger, and during the heating operation, the intermediate pressure refrigerant flowing through the intermediate refrigerant pipe is transferred to the intermediate heat exchanger bypass pipe.
  • the intermediate heat exchanger is bypassed and a part of the refrigerant cooled in the use side heat exchanger is led to the intermediate heat exchanger by the suction return pipe and the intermediate heat exchanger return pipe to evaporate, and the compression mechanism Can be returned to the inhalation side.
  • the refrigeration apparatus is the refrigeration apparatus according to the second aspect of the invention, wherein the refrigerant discharged from the compression element on the front stage side through the intermediate heat exchanger bypass pipe at the start of operation with the switching mechanism in the cooling operation state. Is sucked into the compression element on the rear stage side, and the intermediate heat exchanger is connected to the suction side of the compression mechanism through the suction return pipe.
  • a refrigeration apparatus is the refrigeration apparatus according to the second or third aspect, wherein the intermediate heat exchanger return pipe is provided with a flow rate adjusting valve.
  • this refrigeration apparatus it is possible to prevent the refrigerant from flowing into the intermediate heat exchanger return pipe during the cooling operation, and the flow rate of the refrigerant flowing through the heat source side heat exchanger and the flow rate of the refrigerant flowing through the intermediate heat exchanger during the heating operation. Can be reliably distributed.
  • a refrigeration apparatus is the refrigeration apparatus according to any of the first to fourth aspects of the present invention, wherein the heat source side heat exchanger and the utilization side heat exchanger are used between the heat source side heat exchanger and the utilization side heat exchanger.
  • the expansion device that expands the refrigerant flowing between the heat exchanger and the side heat exchanger in an isentropic manner when the refrigerant flows from the heat source side heat exchanger toward the user side heat exchanger, and from the user side heat exchanger to the heat source side
  • the refrigerant is connected via a rectifying circuit that rectifies the refrigerant so that the refrigerant flows in from the inlet of the expansion device.
  • the coefficient of performance can be increased and the energy can be recovered by the expansion device, so that the operation efficiency during the cooling operation and the heating operation can be further improved. it can.
  • a refrigeration apparatus is the refrigeration apparatus according to the fifth aspect of the invention, wherein a gas-liquid separator that performs gas-liquid separation of the refrigerant is connected to the outlet of the expansion device, A rear-stage injection pipe for returning the gas refrigerant separated in the gas-liquid separator to the rear-stage compression element is connected.
  • a gas-liquid separator that performs gas-liquid separation of the refrigerant
  • a rear-stage injection pipe for returning the gas refrigerant separated in the gas-liquid separator to the rear-stage compression element is connected.
  • FIG. 3 is a pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation.
  • FIG. 3 is a temperature-entropy diagram illustrating a refrigeration cycle during cooling operation.
  • FIG. 3 is a pressure-enthalpy diagram illustrating a refrigeration cycle during heating operation.
  • FIG. 3 is a temperature-entropy diagram illustrating a refrigeration cycle during heating operation.
  • FIG. 1 It is a flowchart of the cooling start control. It is a figure which shows the flow of the refrigerant
  • FIG. It is a schematic block diagram of the air conditioning apparatus concerning the modification 3.
  • FIG. 1 It is a schematic block diagram of the air conditioning apparatus concerning the modification 3.
  • FIG. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation in an air conditioner according to Modification 3.
  • FIG. 10 is a temperature-entropy diagram illustrating a refrigeration cycle during cooling operation in an air conditioner according to Modification 3.
  • FIG. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during heating operation in an air conditioner according to Modification 3.
  • FIG. 10 is a temperature-entropy diagram illustrating a refrigeration cycle during heating operation in an air conditioner according to Modification 3. It is a schematic block diagram of the air conditioning apparatus concerning the modification 4.
  • FIG. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during heating operation in an air conditioner according to Modification 4.
  • FIG. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during heating operation in an air conditioner according to Modification 4.
  • FIG. 10 is a temperature-entropy diagram illustrating a refrigeration cycle during heating operation in an air conditioner according to Modification 4. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5.
  • FIG. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation in an air conditioner according to Modification 5;
  • FIG. 10 is a temperature-entropy diagram illustrating a refrigeration cycle during cooling operation in an air conditioner according to Modification 5;
  • It is a schematic block diagram of the air conditioning apparatus concerning the modification 7.
  • Air conditioning equipment (refrigeration equipment) 2, 102, 202, 302 Compression mechanism 3 Switching mechanism 4 Heat source side heat exchanger 6 User side heat exchanger 7,307 Intermediate heat exchanger 8, 308 Intermediate refrigerant pipe 9, 309 Intermediate heat exchanger bypass pipe 92, 392 First 2 Suction return pipe 94, 394 Intermediate heat exchanger return pipe 94b, 394b Intermediate heat exchanger return valve (flow control valve) 97 Expansion device 17 Rectifier circuit (bridge circuit) 18 Receiver (gas-liquid separator) 18c Second rear injection pipe
  • FIG. 1 is a schematic configuration diagram of an air conditioner 1 as an embodiment of a refrigeration apparatus according to the present invention.
  • the air conditioner 1 has a refrigerant circuit 10 configured to be capable of switching between a cooling operation and a heating operation, and uses a refrigerant (here, carbon dioxide) that operates in a supercritical region, and is a two-stage compression refrigeration cycle. It is a device that performs.
  • the refrigerant circuit 10 of the air conditioner 1 mainly includes a compression mechanism 2, a switching mechanism 3, a heat source side heat exchanger 4, a bridge circuit 17, a receiver 18, a first expansion mechanism 5a, and a second expansion mechanism.
  • the compression mechanism 2 includes a compressor 21 that compresses a refrigerant in two stages with two compression elements.
  • the compressor 21 has a sealed structure in which a compressor drive motor 21b, a drive shaft 21c, and compression elements 2c and 2d are accommodated in a casing 21a.
  • the compressor drive motor 21b is connected to the drive shaft 21c.
  • the drive shaft 21c is connected to the two compression elements 2c and 2d. That is, in the compressor 21, two compression elements 2c and 2d are connected to a single drive shaft 21c, and the two compression elements 2c and 2d are both rotationally driven by the compressor drive motor 21b. It has a stage compression structure.
  • the compression elements 2c and 2d are positive displacement compression elements such as a rotary type and a scroll type in the present embodiment.
  • the compressor 21 sucks the refrigerant from the suction pipe 2a, compresses the sucked refrigerant by the compression element 2c, discharges the refrigerant to the intermediate refrigerant pipe 8, and discharges the refrigerant discharged to the intermediate refrigerant pipe 8 to the compression element 2d. And the refrigerant is further compressed and then discharged to the discharge pipe 2b.
  • the intermediate refrigerant pipe 8 sucks the intermediate-pressure refrigerant in the refrigeration cycle discharged from the compression element 2c connected to the front stage side of the compression element 2d into the compression element 2d connected to the rear stage side of the compression element 2c. It is a refrigerant pipe for making it.
  • the discharge pipe 2b is a refrigerant pipe for sending the refrigerant discharged from the compression mechanism 2 to the switching mechanism 3.
  • the discharge pipe 2b is provided with an oil separation mechanism 41 and a check mechanism 42.
  • the oil separation mechanism 41 is a mechanism that separates the refrigeration oil accompanying the refrigerant discharged from the compression mechanism 2 from the refrigerant and returns it to the suction side of the compression mechanism 2, and is mainly accompanied by the refrigerant discharged from the compression mechanism 2.
  • An oil separator 41 a that separates the refrigeration oil from the refrigerant
  • an oil return pipe 41 b that is connected to the oil separator 41 a and returns the refrigeration oil separated from the refrigerant to the suction pipe 2 a of the compression mechanism 2.
  • the oil return pipe 41b is provided with a pressure reducing mechanism 41c for reducing the pressure of the refrigerating machine oil flowing through the oil return pipe 41b.
  • a capillary tube is used as the decompression mechanism 41c.
  • the check mechanism 42 allows the refrigerant to flow from the discharge side of the compression mechanism 2 to the heat source side heat exchanger 4 as a radiator, and discharges the compression mechanism 2 from the heat source side heat exchanger 4 as a radiator.
  • This is a mechanism for blocking the flow of refrigerant to the side, and a check valve is used in this embodiment.
  • the compression mechanism 2 has the two compression elements 2c and 2d, and the refrigerant discharged from the compression element on the front stage of these compression elements 2c and 2d is returned to the rear stage side.
  • the compression elements are sequentially compressed by the compression elements.
  • the switching mechanism 3 is a mechanism for switching the flow direction of the refrigerant in the refrigerant circuit 10, and is used as a radiator for the refrigerant compressed by the compression mechanism 2 and used in the cooling operation during the cooling operation.
  • the discharge side of the compression mechanism 2 and one end of the heat source side heat exchanger 4 are connected and the compressor 21
  • the suction side and the use side heat exchanger 6 are connected (refer to the solid line of the switching mechanism 3 in FIG. 1, hereinafter, the state of the switching mechanism 3 is referred to as “cooling operation state”).
  • the switching mechanism 3 is a four-way switching valve connected to the suction side of the compression mechanism 2, the discharge side of the compression mechanism 2, the heat source side heat exchanger 4, and the use side heat exchanger 6.
  • the switching mechanism 3 is not limited to a four-way switching valve, and is configured to have a function of switching the refrigerant flow direction as described above, for example, by combining a plurality of electromagnetic valves. There may be.
  • the compression mechanism 2 the heat source side heat exchanger 4 and the use side heat exchanger 6 constituting the refrigerant circuit 10
  • the compression mechanism 2 the heat source side that functions as a refrigerant radiator.
  • the heat source side heat exchanger 4 is a heat exchanger that functions as a refrigerant radiator or an evaporator. One end of the heat source side heat exchanger 4 is connected to the switching mechanism 3, and the other end is connected to the first expansion mechanism 5 a via the bridge circuit 17. Although not shown here, the heat source side heat exchanger 4 is supplied with water and air as a cooling source for exchanging heat with the refrigerant flowing through the heat source side heat exchanger 4.
  • the bridge circuit 17 is provided between the heat source side heat exchanger 4 and the use side heat exchanger 6, and is connected to a receiver inlet pipe 18 a connected to the inlet of the receiver 18 and an outlet of the receiver 18. It is connected to the receiver outlet pipe 18b.
  • the bridge circuit 17 has four check valves 17a, 17b, 17c, and 17d.
  • the inlet check valve 17a is a check valve that only allows the refrigerant to flow from the heat source side heat exchanger 4 to the receiver inlet pipe 18a.
  • the inlet check valve 17b is a check valve that allows only the refrigerant to flow from the use side heat exchanger 6 to the receiver inlet pipe 18a.
  • the inlet check valves 17a and 17b have a function of circulating the refrigerant from one of the heat source side heat exchanger 4 and the use side heat exchanger 6 to the receiver inlet pipe 18a.
  • the outlet check valve 17 c is a check valve that allows only the refrigerant to flow from the receiver outlet pipe 18 b to the use side heat exchanger 6.
  • the outlet check valve 17d is a check valve that allows only the refrigerant to flow from the receiver outlet pipe 18b to the heat source side heat exchanger 4. That is, the outlet check valves 17c and 17d have a function of circulating the refrigerant from the receiver outlet pipe 18b to the other of the heat source side heat exchanger 4 and the use side heat exchanger 6.
  • the first expansion mechanism 5a is a mechanism that depressurizes the refrigerant provided in the receiver inlet pipe 18a, and an electric expansion valve is used in the present embodiment.
  • the first expansion mechanism 5a saturates the refrigerant before sending the high-pressure refrigerant cooled in the heat source side heat exchanger 4 to the use side heat exchanger 6 via the receiver 18.
  • the pressure is reduced to near the pressure, and during the heating operation, the high-pressure refrigerant cooled in the use side heat exchanger 6 is reduced to near the saturation pressure of the refrigerant before being sent to the heat source side heat exchanger 4 via the receiver 18.
  • the receiver 18 is depressurized by the first expansion mechanism 5a so as to be able to store surplus refrigerant generated according to the operating state such as the refrigerant circulation amount in the refrigerant circuit 10 is different between the cooling operation and the heating operation.
  • the inlet is connected to the receiver inlet pipe 18a, and the outlet thereof is connected to the receiver outlet pipe 18b.
  • the receiver 18 also has a first suction return pipe that can extract the refrigerant from the receiver 18 and return it to the suction pipe 2a of the compression mechanism 2 (that is, the suction side of the compression element 2c on the front stage side of the compression mechanism 2).
  • 18f is connected.
  • the first suction return pipe 18f is provided with a first suction return on / off valve 18g.
  • the first suction return on / off valve 18g is an electromagnetic valve in the present embodiment.
  • the second expansion mechanism 5b is a mechanism that depressurizes the refrigerant provided in the receiver outlet pipe 18b, and an electric expansion valve is used in the present embodiment.
  • the second expansion mechanism 5b is at a low pressure in the refrigeration cycle before the refrigerant decompressed by the first expansion mechanism 5a is sent to the use-side heat exchanger 6 via the receiver 18 during the cooling operation.
  • the refrigerant decompressed by the first expansion mechanism 5a is further depressurized until it reaches a low pressure in the refrigeration cycle before being sent to the heat source side heat exchanger 4 via the receiver 18.
  • the use side heat exchanger 6 is a heat exchanger that functions as a refrigerant evaporator or a radiator.
  • One end of the use side heat exchanger 6 is connected to the first expansion mechanism 5 a via a bridge circuit, and the other end is connected to the switching mechanism 3.
  • the use side heat exchanger 6 is supplied with water and air as a heat source for exchanging heat with the refrigerant flowing through the use side heat exchanger 6.
  • the heat source side heat exchanger 4 when the switching mechanism 3 is in the cooling operation state by the bridge circuit 17, the receiver 18, the receiver inlet pipe 18a, and the receiver outlet pipe 18b, the heat source side heat exchanger 4 is cooled.
  • the high-pressure refrigerant is supplied to the inlet check valve 17a of the bridge circuit 17, the first expansion mechanism 5a of the receiver inlet pipe 18a, the second expansion mechanism 5b of the receiver 18, the receiver outlet pipe 18b, and the outlet check valve 17c of the bridge circuit 17. It can be sent to the use side heat exchanger 6 through.
  • the switching mechanism 3 when the switching mechanism 3 is in the heating operation state, the high-pressure refrigerant cooled in the use-side heat exchanger 6 is converted into the first expansion mechanism of the inlet check valve 17b of the bridge circuit 17 and the receiver inlet pipe 18a. 5a, the receiver 18, the second expansion mechanism 5b of the receiver outlet pipe 18b, and the outlet check valve 17d of the bridge circuit 17 can be sent to the heat source side heat exchanger 4.
  • the intermediate heat exchanger 7 is provided in the intermediate refrigerant pipe 8 and dissipates heat in the refrigerant cooler that is discharged from the preceding compression element 2c and sucked into the compression element 2d or in the use-side heat exchanger 6. It is a heat exchanger capable of functioning as a refrigerant evaporator. Although not shown here, the intermediate heat exchanger 7 is supplied with water and air as a cooling source for exchanging heat with the refrigerant flowing through the intermediate heat exchanger 7. Thus, the intermediate heat exchanger 7 can be said to be a cooler using an external heat source in the sense that it does not use the refrigerant circulating in the refrigerant circuit 10.
  • An intermediate heat exchanger bypass pipe 9 is connected to the intermediate refrigerant pipe 8 so as to bypass the intermediate heat exchanger 7.
  • the intermediate heat exchanger bypass pipe 9 is a refrigerant pipe that limits the flow rate of the refrigerant flowing through the intermediate heat exchanger 7.
  • the intermediate heat exchanger bypass pipe 9 is provided with an intermediate heat exchanger bypass opening / closing valve 11.
  • the intermediate heat exchanger bypass on-off valve 11 is a solenoid valve in the present embodiment.
  • the intermediate heat exchanger bypass on-off valve 11 basically sets the switching mechanism 3 in the cooling operation state except for a case where a temporary operation such as cooling start control described later is performed. It closes at the time and is controlled to open when the switching mechanism 3 is in the heating operation state. That is, the intermediate heat exchanger bypass on-off valve 11 is controlled to be closed when performing the cooling operation and to be opened when performing the heating operation.
  • the intermediate refrigerant pipe 8 has an intermediate portion between the connecting portion of the intermediate heat exchanger bypass pipe 9 and the compression element 2c side end on the front stage side to the compression element 2c side end on the front stage side of the intermediate heat exchanger 7.
  • a heat exchanger on / off valve 12 is provided.
  • the intermediate heat exchanger on / off valve 12 is a mechanism that limits the flow rate of the refrigerant flowing through the intermediate heat exchanger 7.
  • the intermediate heat exchanger on / off valve 12 is an electromagnetic valve in the present embodiment.
  • the intermediate heat exchanger on / off valve 12 is basically in a state where the switching mechanism 3 is in a cooling operation state except for a case where a temporary operation such as cooling start control described later is performed.
  • the intermediate refrigerant pipe 8 allows the refrigerant to flow from the discharge side of the upstream compression element 2c to the suction side of the downstream compression element 2d, and from the suction side of the downstream compression element 2d to the upstream side.
  • a check mechanism 15 is provided for blocking the flow of the refrigerant to the discharge side of the compression element 2c on the side.
  • the check mechanism 15 is a check valve in the present embodiment. In the present embodiment, the check mechanism 15 is connected to the compression element 2d side end of the intermediate heat exchanger bypass pipe 9 from the compression element 2d side end of the intermediate heat exchanger 7 on the rear stage side. It is provided in the part to the connection part.
  • a second suction return pipe 92 is connected to one end of the intermediate heat exchanger 7 (here, the end on the compression element 2 c side on the front stage side), and the other end (here, the rear stage) of the intermediate heat exchanger 7.
  • the intermediate heat exchanger return pipe 94 is connected to the side compression element 2d side end).
  • the second suction return pipe 92 is in a state where the refrigerant discharged from the front-stage compression element 2c through the intermediate heat exchanger bypass pipe 9 is sucked into the rear-stage compression element 2d.
  • the intermediate heat exchanger return pipe 94 allows the refrigerant discharged from the front-stage compression element 2c through the intermediate heat exchanger bypass pipe 9 to be sucked into the rear-stage compression element 2d, and the switching mechanism 3 is During the heating operation state, between the use side heat exchanger 6 and the heat source side heat exchanger 4 (here, the second expansion mechanism 5b for depressurizing the refrigerant until the pressure becomes low in the refrigeration cycle and the evaporator) This is a refrigerant pipe for connecting the heat source side heat exchanger 4) and the other end of the intermediate heat exchanger 7.
  • one end of the second suction return pipe 92 is connected to the front end of the intermediate heat exchanger bypass pipe 9 of the intermediate refrigerant pipe 8 from the end of the compression element 2c side of the intermediate heat exchanger 7.
  • the other end is connected to the suction side of the compression mechanism 2 (here, the suction pipe 2a).
  • the intermediate heat exchanger return pipe 94 has one end connected to a portion from the second expansion mechanism 5 b to the heat source side heat exchanger 4, and the other end connected to the intermediate heat exchanger 7 of the intermediate refrigerant pipe 8. Is connected to the portion from the compression element 2c side end of the previous stage side to the check mechanism 15.
  • the second suction return pipe 92 is provided with a second suction return on / off valve 92a
  • the intermediate heat exchanger return pipe 94 is provided with an intermediate heat exchanger return on / off valve 94a.
  • the second suction return on / off valve 92a and the intermediate heat exchanger return on / off valve 94a are electromagnetic valves in the present embodiment.
  • the second suction return on / off valve 92a is basically in a state where the switching mechanism 3 is in the cooling operation state except for a case where a temporary operation such as cooling start control described later is performed. The control is performed so that the switching mechanism 3 is opened when the switching mechanism 3 is in the heating operation state.
  • the intermediate heat exchanger return on / off valve 94a is closed when the switching mechanism 3 is in the cooling operation state, including the case where temporary operation such as cooling start control described later is performed, and the switching mechanism 3 is heated. Control to open when in the state.
  • the intermediate-pressure refrigerant flowing through the intermediate refrigerant pipe 8 is mainly supplied by the intermediate heat exchanger bypass pipe 9, the second suction return pipe 92, and the intermediate heat exchanger return pipe 94 during the cooling operation.
  • the refrigerant can be cooled by the intermediate heat exchanger 7, and during the heating operation, the intermediate pressure refrigerant flowing through the intermediate refrigerant pipe 8 is bypassed by the intermediate heat exchanger bypass pipe 9 and the second suction return is performed.
  • the pipe 92 and the intermediate heat exchanger return pipe 94 a part of the refrigerant cooled in the use side heat exchanger 6 can be led to the intermediate heat exchanger 7 to be evaporated and returned to the suction side of the compression mechanism 2. It has become.
  • the air conditioner 1 includes a compression mechanism 2, a switching mechanism 3, expansion mechanisms 5a and 5b, an intermediate heat exchanger bypass opening / closing valve 11, an intermediate heat exchanger opening / closing valve 12, a first suction return opening / closing valve. It has a control part which controls operation of each part which constitutes air harmony device 1, such as valve 18g, the 2nd suction return on-off valve 92a, and intermediate heat exchanger return on-off valve 94a.
  • FIG. 2 is a diagram showing the flow of the refrigerant in the air conditioner 1 during the cooling operation
  • FIG. 3 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation
  • FIG. 5 is a temperature-entropy diagram illustrating a refrigeration cycle during cooling operation
  • FIG. 5 is a diagram illustrating a flow of refrigerant in the air conditioner 1 during heating operation
  • FIG. 6 is a diagram during heating operation
  • 7 is a pressure-enthalpy diagram illustrating the refrigeration cycle
  • FIG. 7 is a temperature-entropy diagram illustrating the refrigeration cycle during heating operation
  • FIGS. 8 is a flowchart of the cooling start control.
  • 9 is a diagram illustrating the flow of the refrigerant in the air conditioner 1 during the cooling start control.
  • high pressure means high pressure in the refrigeration cycle (that is, pressure at points D, D ′, and E in FIGS. 3 and 4 and pressure at points D, D ′, and F in FIGS. 6 and 7).
  • Low pressure means the low pressure in the refrigeration cycle (that is, the pressure at points A and F in FIGS. 3 and 4 and the pressure at points A, E and V in FIGS. 6 and 7).
  • “Means an intermediate pressure in the refrigeration cycle that is, pressure at points B1 and C1 in FIGS. 3 and 4 and pressure at points B1, C1 and C1 'in FIGS. 6 and 7).
  • the switching mechanism 3 is in the cooling operation state indicated by the solid lines in FIGS.
  • the opening degree of the first expansion mechanism 5a and the second expansion mechanism 5b is adjusted. Since the switching mechanism 3 is in the cooling operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is opened, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is closed. Thus, the intermediate heat exchanger 7 is brought into a state of functioning as a cooler, and the second suction return on / off valve 92a of the second suction return pipe 92 is closed, whereby the intermediate heat exchanger 7 and the compression mechanism 2 are closed.
  • the suction side is not connected (except during the cooling start control described later), and the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94 is closed, so that the user side The heat exchanger 6 and the heat source side heat exchanger 4 are not connected to the intermediate heat exchanger 7.
  • a low-pressure refrigerant (see point A in FIGS. 1 to 4) is sucked into the compression mechanism 2 from the suction pipe 2a, and is first compressed to an intermediate pressure by the compression element 2c.
  • the refrigerant is discharged into the refrigerant pipe 8 (see point B1 in FIGS. 1 to 4).
  • the intermediate-pressure refrigerant discharged from the upstream-side compression element 2c is cooled by exchanging heat with water or air as a cooling source in the intermediate heat exchanger 7 (point C1 in FIGS. 1 to 4). reference).
  • the refrigerant cooled in the intermediate heat exchanger 7 is then sucked into the compression element 2d connected to the rear stage side of the compression element 2c, further compressed, and discharged from the compression mechanism 2 to the discharge pipe 2b ( (See point D in FIGS. 1-4).
  • the high-pressure refrigerant discharged from the compression mechanism 2 is compressed to a pressure exceeding the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 3) by the two-stage compression operation by the compression elements 2c and 2d.
  • the high-pressure refrigerant discharged from the compression mechanism 2 flows into the oil separator 41a constituting the oil separation mechanism 41, and the accompanying refrigeration oil is separated.
  • the refrigerating machine oil separated from the high-pressure refrigerant in the oil separator 41a flows into the oil return pipe 41b constituting the oil separation mechanism 41, and is compressed after being reduced in pressure by the pressure reduction mechanism 41c provided in the oil return pipe 41b. It is returned to the suction pipe 2a of the mechanism 2 and again sucked into the compression mechanism 2.
  • the high-pressure refrigerant after the refrigerating machine oil is separated in the oil separation mechanism 41 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator through the check mechanism 42 and the switching mechanism 3.
  • the high-pressure refrigerant sent to the heat source side heat exchanger 4 is cooled by exchanging heat with water or air as a cooling source in the heat source side heat exchanger 4 (point E in FIGS. 2 to 4). reference). Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 flows into the receiver inlet pipe 18a through the inlet check valve 17a of the bridge circuit 17 and is reduced to near the saturation pressure by the first expansion mechanism 5a. (See point I in FIGS. 1 and 2).
  • the refrigerant stored in the receiver 18 is sent to the receiver outlet pipe 18b and is reduced in pressure by the second expansion mechanism 5b to become a low-pressure gas-liquid two-phase refrigerant, and the outlet check valve 17c of the bridge circuit 17 is used. And is sent to the use side heat exchanger 6 functioning as a refrigerant evaporator (see point F in FIGS. 1 to 4). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 is heated by exchanging heat with water or air as a heating source to evaporate (FIG. 1 to FIG. 1). (See point A in 4). Then, the low-pressure refrigerant heated in the use side heat exchanger 6 is again sucked into the compression mechanism 2 via the switching mechanism 3. In this way, the cooling operation is performed.
  • the intermediate heat exchanger 7 is provided in the intermediate refrigerant pipe 8 for allowing the refrigerant discharged from the compression element 2c to be sucked into the compression element 2d, and in the cooling operation, Since the heat exchanger on / off valve 12 is opened and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is closed, the intermediate heat exchanger 7 is in a state of functioning as a cooler. Compared to the case where the heat exchanger 7 is not provided (in this case, the refrigeration cycle is performed in the order of point A ⁇ point B1 ⁇ point D ′ ⁇ point E ⁇ point F in FIGS.
  • the switching mechanism 3 is in the heating operation state indicated by the broken lines in FIGS.
  • the opening degree of the first expansion mechanism 5a and the second expansion mechanism 5b is adjusted. Since the switching mechanism 3 is in a heating operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is closed, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is opened. As a result, the intermediate heat exchanger 7 does not function as a cooler. Further, since the switching mechanism 3 is in the heating operation state, the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected by opening the second suction return on / off valve 92a of the second suction return pipe 92. The intermediate heat exchanger return pipe 94 is opened, and the intermediate heat exchanger return opening / closing valve 94a is opened, whereby the intermediate heat exchanger is connected between the use side heat exchanger 6 and the heat source side heat exchanger 4. 7 is connected.
  • low-pressure refrigerant (see point A in FIGS. 1 and 5 to 7) is sucked into the compression mechanism 2 from the suction pipe 2a and first compressed to an intermediate pressure by the compression element 2c. Thereafter, the refrigerant is discharged into the intermediate refrigerant pipe 8 (see point B1 in FIGS. 1 and 5 to 7). Unlike the cooling operation, the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c does not pass through the intermediate heat exchanger 7 (that is, is not cooled), and the intermediate heat exchanger bypass pipe. 9 (refer to point C1 in FIGS.
  • the high-pressure refrigerant discharged from the compression mechanism 2 is subjected to the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 6) by the two-stage compression operation by the compression elements 2c and 2d as in the cooling operation. ) Compressed to a pressure exceeding The high-pressure refrigerant discharged from the compression mechanism 2 flows into the oil separator 41a constituting the oil separation mechanism 41, and the accompanying refrigeration oil is separated.
  • the refrigerating machine oil separated from the high-pressure refrigerant in the oil separator 41a flows into the oil return pipe 41b constituting the oil separation mechanism 41, and is compressed after being reduced in pressure by the pressure reduction mechanism 41c provided in the oil return pipe 41b. It is returned to the suction pipe 2a of the mechanism 2 and again sucked into the compression mechanism 2.
  • the high-pressure refrigerant after the refrigerating machine oil is separated in the oil separation mechanism 41 is sent to the use side heat exchanger 6 functioning as a refrigerant radiator through the check mechanism 42 and the switching mechanism 3 to be cooled. It is cooled by exchanging heat with water or air as a source (see point F in FIGS. 1 and 5 to 7).
  • the high-pressure refrigerant cooled in the use-side heat exchanger 6 flows into the receiver inlet pipe 18a through the inlet check valve 17b of the bridge circuit 17, and is reduced to near the saturation pressure by the first expansion mechanism 5a. (See point I in FIGS. 1 and 5). Then, the refrigerant stored in the receiver 18 is sent to the receiver outlet pipe 18b and is reduced in pressure by the second expansion mechanism 5b to become a low-pressure gas-liquid two-phase refrigerant, and the outlet check valve 17d of the bridge circuit 17 is supplied.
  • the intermediate heat exchanger return pipe 94 and also to the intermediate heat exchanger 7 functioning as the refrigerant evaporator (FIG. 1, FIG. 1). 5 to point E in FIG. 7).
  • the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 is heated by exchanging heat with water or air as a heating source to evaporate (FIG. 1, FIG. 1). 5 to point A in FIG. 7). Further, the low-pressure gas-liquid two-phase refrigerant sent to the intermediate heat exchanger 7 is also heated by exchanging heat with water or air as a heating source (FIGS. 1 and 5). (See point V in FIG. 7).
  • the low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 is again sucked into the compression mechanism 2 via the switching mechanism 3.
  • the low-pressure refrigerant heated and evaporated in the intermediate heat exchanger 7 is again sucked into the compression mechanism 2 through the second suction return pipe 92. In this way, the heating operation is performed.
  • the intermediate heat exchanger on / off valve 12 in the heating operation in which the switching mechanism 3 is in the heating operation state, the intermediate heat exchanger on / off valve 12 is closed and the intermediate heat exchanger bypass on / off valve 11 is opened. Therefore, the intermediate heat exchanger 7 is not functioning as a cooler. Therefore, when only the intermediate heat exchanger 7 is provided or when the intermediate heat exchanger 7 is functioned as a cooler as in the above cooling operation. (In this case, the refrigeration cycle is performed in the order of point A ⁇ point B1 ⁇ point C1 ′ ⁇ point D ′ ⁇ point F ⁇ point E in FIGS. 6 and 7). The decrease in the temperature of the refrigerant to be performed is suppressed (see points D and D ′ in FIG. 7).
  • this air conditioning apparatus 1 compared with the case where only the intermediate heat exchanger 7 is provided or the case where the intermediate heat exchanger 7 functions as a cooler as in the above-described cooling operation, the heat radiation to the outside is reduced. It is possible to suppress the temperature drop of the refrigerant supplied to the use-side heat exchanger 6 that functions as a refrigerant radiator, and the enthalpy difference between point D and point F in FIG. It is possible to prevent a decrease in operating efficiency by suppressing a decrease in heating capacity corresponding to the difference from the enthalpy difference from F.
  • the intermediate heat exchanger 7 in the heating operation in which the switching mechanism 3 is in the heating operation state, is not simply used so that it does not function as a cooler. Together with the heat source side heat exchanger 4, the intermediate heat exchanger 7 is made to function as an evaporator for the refrigerant that has radiated heat in the use side heat exchanger 7, and is also used during heating operation.
  • the heating capacity of the use-side heat exchanger 4 is reduced by increasing the evaporation capacity of the refrigerant during heating operation and increasing the flow rate of the refrigerant circulating in the refrigerant circuit 10 while suppressing heat radiation to the outside. I try to suppress it.
  • the heat dissipation loss in the heat source side heat exchanger 4 that functions as a refrigerant radiator is reduced during the cooling operation, and the operation efficiency during the cooling operation can be improved.
  • the intermediate heat exchanger 7 is effectively used, and the heating capacity in the use-side heat exchanger 4 is suppressed from being lowered so that the operation efficiency during the heating operation is not lowered. be able to.
  • the refrigerant discharged from the compression element 2c on the front stage side through the intermediate heat exchanger bypass pipe 9 is brought into a state of being sucked into the compression element 2d on the rear stage side.
  • the cooling start control for connecting the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 is performed by the two suction return pipe 92.
  • step S1 when a cooling operation start command is issued, the process proceeds to a process of operating various valves in step S2.
  • step S2 the on-off state of the on-off valves 11, 12, 92a is set such that the refrigerant discharged from the front-stage compression element 2c through the intermediate heat exchanger bypass pipe 9 is sucked into the rear-stage compression element 2d, The state is switched to the refrigerant return state in which the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected through the second suction return pipe 92.
  • the intermediate heat exchanger bypass opening / closing valve 11 is opened, and the intermediate heat exchanger opening / closing valve 12 is closed.
  • the intermediate heat exchanger bypass pipe 9 causes a flow in which the refrigerant discharged from the front-stage compression element 2 c is sucked into the rear-stage compression element 2 d without passing through the intermediate heat exchanger 7. That is, the intermediate heat exchanger 7 is not functioned as a cooler, and the refrigerant discharged from the upstream compression element 2c through the intermediate heat exchanger bypass pipe 9 is sucked into the downstream compression element 2d. (See FIG. 9). In such a state, the second suction return on / off valve 92a is opened.
  • the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected by the second suction return pipe 92, and the intermediate heat exchanger 7 (more specifically, the intermediate heat exchange including the intermediate heat exchanger 7 is performed).
  • the pressure of the refrigerant in the portion between the heater on / off valve 12 and the check mechanism 15) is reduced to near the low pressure in the refrigeration cycle, and the refrigerant in the intermediate heat exchanger 7 can be drawn to the suction side of the compression mechanism 2 (See FIG. 9).
  • step S3 the open / close state of the on-off valves 11, 12, 92a in step S2 (that is, the refrigerant return state) is maintained for a predetermined time.
  • the liquid refrigerant accumulated in the intermediate heat exchanger 7 is evaporated under reduced pressure, Without being sucked into the compression element 2d on the side, it is pulled out of the intermediate heat exchanger 7 (more specifically, on the suction side of the compression mechanism 2), and the compression mechanism 2 (here, the compression element 2c on the front stage side) Will be inhaled.
  • the predetermined time is set to a time during which the liquid refrigerant accumulated in the intermediate heat exchanger 7 can be extracted out of the intermediate heat exchanger 7.
  • step S4 the open / close state of the on-off valves 11, 12, 92a is changed so that the refrigerant discharged from the front-stage compression element 2c through the intermediate heat exchanger 7 is sucked into the rear-stage compression element 2d and the second suction is performed. Switching to the refrigerant non-return state in which the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are not connected through the return pipe 92 is performed.
  • the control is shifted to the open / closed state of the valves 11, 12, 92a during the cooling operation described above, and the cooling start control is terminated. Specifically, the second suction return on / off valve 92a is closed. Then, the refrigerant in the intermediate heat exchanger 7 does not flow out to the suction side of the compression mechanism 2. In such a state, the intermediate heat exchanger on / off valve 12 is opened, and the intermediate heat exchanger bypass on / off valve 11 is closed. If it does so, it will be in the state in which the intermediate heat exchanger 7 functions as a cooler.
  • a refrigerant circuit provided with an intermediate heat exchanger switching valve 93 capable of switching between a refrigerant non-return state and a refrigerant return state. It may be 110.
  • the intermediate heat exchanger switching valve 93 is a valve that can be switched between a refrigerant non-return state and a refrigerant return state.
  • the intermediate heat exchanger switching valve 93 is connected to the discharge side of the compression element 2c on the upstream side of the intermediate refrigerant pipe 8.
  • the intermediate refrigerant pipe 8 is connected to the inlet side of the intermediate heat exchanger 7, the intermediate heat exchanger bypass pipe 9 is connected to the front end side of the compression element 2 c, and the second suction return pipe 92 is connected to the intermediate heat exchanger 7 side end.
  • This is a four-way switching valve.
  • the intermediate heat exchanger bypass pipe 9 allows the refrigerant to flow from the discharge side of the front-stage compression element 2c to the suction side of the rear-stage compression element 2d, and sucks the rear-stage compression element 2d.
  • the check mechanism 9a is a check valve in this modification.
  • the refrigerant discharged from the compression element 2c on the upstream side through the intermediate heat exchanger 7 is supplied to the compression element 2d on the downstream side through the intermediate heat exchanger 7.
  • the intermediate heat exchanger switching valve 93 can be used to switch between the refrigerant non-return state and the refrigerant return state. Therefore, the plurality of valves 11, 12, and 92 a as in the above-described embodiment allow The number of valves can be reduced compared to a case where a configuration for switching between the non-return state and the refrigerant return state is employed. Further, since the pressure loss is reduced as compared with the case where a solenoid valve is used, it is possible to suppress a decrease in the intermediate pressure in the refrigeration cycle and to suppress a decrease in operating efficiency.
  • the intermediate heat exchanger 7 and the heat source side heat exchanger 4 are heat exchangers using air as a heat source (that is, a cooling source or a heating source), and both the heat exchangers 4 and 7 are used. It is conceivable to employ a configuration in which air as a heat source is supplied by a common heat source side fan 40 (described later).
  • the air conditioner 1 includes a heat source unit 1a mainly provided with a heat source side fan 40, a heat source side heat exchanger 4 and an intermediate heat exchanger 7, and a use unit mainly provided with a use side heat exchanger 6 (FIG.
  • a heat source unit 1a mainly provided with a heat source side fan 40, a heat source side heat exchanger 4 and an intermediate heat exchanger 7, and a use unit mainly provided with a use side heat exchanger 6
  • FIG. 11 is an external perspective view of the heat source unit 1a (with the fan grill removed)
  • FIG. 12 is a side view of the heat source unit 1a with the right plate of the heat source unit 1a removed.
  • “left” and “right” are based on the case where the heat source unit 1a is viewed from the front plate 24 side.
  • the heat source unit 1a constituting the air conditioner 1 of the present modification is a so-called top-blowing type that sucks air from the side and blows air upward. It has refrigerant circuit components such as the heat source side heat exchanger 4 and the intermediate heat exchanger 7 arranged inside, and devices such as the heat source side fan 40.
  • the casing 71 is a substantially rectangular parallelepiped box, and mainly includes a top plate 72 constituting the top surface of the casing 71, a left plate 73, a right plate 74 constituting the outer peripheral surface of the casing 71, and the front.
  • the plate 75 and the rear plate 76 and the bottom plate 77 are constituted.
  • the top plate 72 is a member that mainly constitutes the top surface of the casing 71.
  • the top plate 72 is a plate-like member having a substantially rectangular shape in a plan view in which the blowing opening 71a is formed at a substantially center.
  • the top plate 72 is provided with a fan grill 78 so as to cover the blowout opening 71a from above.
  • the left plate 73 is a member that mainly constitutes the left surface of the casing 71.
  • the left plate 73 is a plate-like member that is substantially rectangular in a side view extending downward from the left edge of the top plate 72.
  • the left plate 73 is formed with a suction opening 73a almost entirely except for the upper part.
  • the right plate 74 is a member that mainly constitutes the right surface of the casing 71.
  • the right plate 74 is a plate-like member that is substantially rectangular in a side view extending downward from the right edge of the top plate 72.
  • the right plate 74 is formed with a suction opening 74a almost entirely except for the upper part.
  • the front plate 75 is a member that mainly constitutes the front surface of the casing 71.
  • the front plate 75 is formed of a plate-like member that is disposed in order downward from the front edge of the top plate 72 in a substantially rectangular shape.
  • the rear plate 76 is a member that mainly constitutes the rear surface of the casing 71.
  • the rear plate 76 is formed of a plate-like member that is disposed in order downward from the rear edge of the top plate 72 in a substantially rectangular shape.
  • the rear plate 76 is formed with a suction opening 76a in substantially the whole except the upper part.
  • the bottom plate 77 is a member that mainly constitutes the bottom surface of the casing 71.
  • the bottom plate 77 is a plate-like member having a substantially rectangular shape in plan view.
  • the intermediate heat exchanger 7 is integrated with the heat source side heat exchanger 4 while being disposed above the heat source side heat exchanger 4, and is disposed on the bottom plate 77. More specifically, the intermediate heat exchanger 7 is integrated with the heat source side heat exchanger 4 by sharing heat transfer fins. Further, in the present modification, the heat source side heat exchanger 4 and the intermediate heat exchanger 7 are integrated to form a heat exchanger panel having a substantially U shape in plan view, and the suction openings 73a and 74a. , 76a. Further, the heat source side fan 40 is opposed to the blowout opening 71a of the top plate 72, and above the one in which the heat source side heat exchanger 4 and the intermediate heat exchanger 7 are integrated (that is, the heat exchanger panel).
  • the heat source side fan 40 is an axial fan, and is driven to rotate by the fan drive motor 40a so that air as a heat source is sucked into the casing 71 from the suction openings 73a, 74a, 76a, and the heat source side After passing through the heat exchanger 4 and the intermediate heat exchanger 7, the air can be blown upward from the blowout opening 71a (see the arrows indicating the air flow in FIG. 12). That is, the heat source side fan 40 supplies air as a heat source to both the heat source side heat exchanger 4 and the intermediate heat exchanger 7.
  • the external shape of the heat source unit 1a and the shape of the heat source side heat exchanger 4 and the intermediate heat exchanger 7 integrated are not limited to those described above.
  • the intermediate heat exchanger 7 constitutes a heat exchanger panel integrated with the heat source side heat exchanger 4, and is disposed on the upper part of the heat exchanger panel.
  • the intermediate heat exchanger 7 is integrated with the heat source side heat exchanger 4, and the intermediate heat exchanger 7 is arranged on the upper part of the heat exchanger panel in which both are integrated.
  • a refrigeration cycle such as a cooling operation in which a high-pressure refrigerant exceeding the critical pressure Pcp flows may be performed in the heat source side heat exchanger 4 functioning as a radiator (see FIG. 3).
  • the heat transfer coefficient on the refrigerant side of the heat exchanger 7 tends to be lower than the heat transfer coefficient on the refrigerant side of the heat source side heat exchanger 4 that functions as a refrigerant radiator.
  • FIG. 13 shows the value of the heat transfer coefficient in the case where 6.5 MPa carbon dioxide flows at a predetermined mass flow rate in a heat transfer channel having a predetermined channel cross-sectional area (intermediate cold heat exchanger 7 as a cooler).
  • the heat transfer coefficient value of 10 MPa carbon dioxide under the same heat transfer flow path and mass flow rate condition as 6.5 MPa carbon dioxide (heat source side heat exchanger as a radiator) 4 corresponds to the heat transfer coefficient on the refrigerant side 4), and when viewed, the heat source side heat exchanger 4 that functions as a refrigerant radiator and the intermediate heat exchanger 7 that functions as a refrigerant cooler are shown.
  • the value of the heat transfer coefficient of 6.5 MPa carbon dioxide is lower than the value of the heat transfer coefficient of carbon dioxide of 10 MPa in the temperature range of the refrigerant flowing through (about 35 to 70 ° C.).
  • the intermediate heat exchanger 7 is temporarily When integrated with the heat source side heat exchanger 4 in a state of being arranged below the heat source side heat exchanger 4, it is integrated with the heat source side heat exchanger 4 at the lower part of the heat source unit 1a where the flow velocity of air serving as the heat source is small.
  • the intermediate heat exchanger 7 will be arranged, the influence of the reduction in the heat transfer coefficient on the air side of the intermediate heat exchanger 7 due to the arrangement of the intermediate heat exchanger 7 below the heat source unit 1a, and the intermediate heat exchange This is because the heat transfer performance of the intermediate heat exchanger 7 is deteriorated by overlapping with the effect that the heat transfer coefficient on the refrigerant side of the heat exchanger 7 becomes lower than the heat transfer coefficient on the refrigerant side of the heat source side heat exchanger 4. .
  • the intermediate heat exchanger bypass pipe 9 is used during heating operation, the refrigerant discharged from the front-stage compression element 2c and sucked into the rear-stage compression element 2d is intermediate.
  • the intermediate air disposed at the position where the flow rate of air as the heat source is the highest in consideration of the heat transfer coefficient during the cooling operation. The heat exchanger 7 does not contribute at all during the heating operation, and the demerit of not effectively using the intermediate heat exchanger 7 is great.
  • the intermediate heat exchanger bypass pipe 9 is used to discharge from the upstream compression element 2c to the downstream compression element 2d.
  • the intermediate heat exchanger 7 functions as a refrigerant evaporator, thereby contributing to an increase in evaporation capacity during heating operation.
  • the first rear-stage injection pipe 19 and the economizer heat exchanger 20 are used.
  • the refrigerant circuit 210 can be provided.
  • the first second-stage injection pipe 19 has a function of branching the refrigerant flowing between the heat source-side heat exchanger 4 and the use-side heat exchanger 6 and returning it to the compression element 2d on the rear stage side of the compression mechanism 2.
  • the first second-stage injection pipe 19 is provided to branch the refrigerant flowing through the receiver inlet pipe 18a and return it to the suction side of the second-stage compression element 2d.
  • the first second-stage injection pipe 19 is positioned on the upstream side of the first expansion mechanism 5a of the receiver inlet pipe 18a (that is, when the switching mechanism 3 is in the cooling operation state, the heat source side heat The refrigerant is branched from the exchanger 4 and the first expansion mechanism 5a) and returned to the downstream position of the intermediate heat exchanger 7 in the intermediate refrigerant pipe 8.
  • the first second-stage injection pipe 19 is provided with a first second-stage injection valve 19a capable of opening degree control.
  • the 1st latter stage side injection valve 19a is an electric expansion valve in this modification.
  • the economizer heat exchanger 20 includes a refrigerant flowing between the heat source side heat exchanger 4 and the use side heat exchanger 6 and a refrigerant flowing through the first second-stage injection pipe 19 (more specifically, a first second-stage injection valve).
  • 19a is a heat exchanger that performs heat exchange with the refrigerant after being reduced in pressure to near the intermediate pressure.
  • the economizer heat exchanger 20 is positioned on the upstream side of the first expansion mechanism 5a of the receiver inlet pipe 18a (that is, when the switching mechanism 3 is in the cooling operation state, the heat source side heat exchanger 4 Between the refrigerant flowing between the refrigerant and the first expansion mechanism 5a) and the refrigerant flowing through the first second-stage injection pipe 19, and a flow path through which the two refrigerants face each other.
  • the economizer heat exchanger 20 is provided on the downstream side of the position where the first second-stage injection pipe 19 is branched from the receiver inlet pipe 18a.
  • the refrigerant flowing between the heat source side heat exchanger 4 and the use side heat exchanger 6 is transferred to the first second-stage injection pipe 19 before heat exchange is performed in the economizer heat exchanger 20 in the receiver inlet pipe 18a.
  • the economizer heat exchanger 20 exchanges heat with the refrigerant flowing through the first second-stage injection pipe 19.
  • the high-pressure refrigerant cooled in the heat source side heat exchanger 4 is converted into the inlet check valve 17a of the bridge circuit 17 and the economizer heat. It is sent to the use side heat exchanger 6 through the exchanger 20, the first expansion mechanism 5a of the receiver inlet pipe 18a, the receiver 18, the second expansion mechanism 5b of the receiver outlet pipe 18b, and the outlet check valve 17c of the bridge circuit 17. It can be done. Further, when the switching mechanism 3 is in the heating operation state, the high-pressure refrigerant cooled in the use side heat exchanger 6 is supplied to the inlet check valve 17b of the bridge circuit 17, the economizer heat exchanger 20, the receiver inlet pipe. It can be sent to the heat source side heat exchanger 4 through the first expansion mechanism 5a of 18a, the receiver 18, the second expansion mechanism 5b of the receiver outlet pipe 18b, and the outlet check valve 17d of the bridge circuit 17.
  • the intermediate refrigerant pipe 8 or the compression mechanism 2 is provided with an intermediate pressure sensor 54 that detects the pressure of the refrigerant flowing through the intermediate refrigerant pipe 8.
  • An economizer outlet temperature sensor 55 that detects the temperature of the refrigerant at the outlet of the economizer heat exchanger 20 on the first rear-stage injection pipe 19 side is provided at the outlet of the economizer heat exchanger 20 on the first rear-stage injection pipe 19 side.
  • FIG. 18 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the heating operation
  • FIG. 18 is a temperature-entropy diagram illustrating the refrigeration cycle during the heating operation.
  • cooling start control is the same as that in the above-described embodiment, the description thereof is omitted here.
  • operation control in the following cooling operation and heating operation is performed by the control unit (not shown) in the above-described embodiment.
  • “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points D, D ′, E, and H in FIGS. 15 and 16, and points D, D ′, and FIGS. 17 and 18).
  • Pressure at F, H and “low pressure” means low pressure in the refrigeration cycle (that is, pressure at points A and F in Figs. 15 and 16 and pressure at points A, E and V in Figs. 17 and 18).
  • the “intermediate pressure” means an intermediate pressure in the refrigeration cycle (that is, pressure at points B1, C1, G, J, and K in FIGS. 15 to 18).
  • the switching mechanism 3 is in the cooling operation state indicated by the solid line in FIG.
  • the opening degree of the first expansion mechanism 5a and the second expansion mechanism 5b is adjusted.
  • the opening degree of the first second-stage injection valve 19a is also adjusted. More specifically, in this modification, the first second-stage injection valve 19a has an opening degree so that the degree of superheat of the refrigerant at the outlet of the economizer heat exchanger 20 on the first second-stage injection pipe 19 side becomes a target value. So-called superheat control is performed.
  • the superheat degree of the refrigerant at the outlet of the economizer heat exchanger 20 on the first second-stage injection pipe 19 side is obtained by converting the intermediate pressure detected by the intermediate pressure sensor 54 into the saturation temperature, and the economizer outlet temperature sensor 55. This is obtained by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature detected by the above.
  • a temperature sensor is provided at the inlet of the economizer heat exchanger 20 on the first second-stage injection pipe 19 side, and the refrigerant temperature detected by this temperature sensor is used as the economizer outlet temperature sensor 55.
  • the degree of superheat of the refrigerant at the outlet of the economizer heat exchanger 20 on the first second-stage injection pipe 19 side may be obtained by subtracting from the refrigerant temperature detected by the above.
  • the adjustment of the opening degree of the first second-stage injection valve 19a is not limited to the superheat degree control, and, for example, is to open a predetermined opening degree according to the refrigerant circulation amount in the refrigerant circuit 10 or the like. Also good. Since the switching mechanism 3 is in the cooling operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is opened, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is closed.
  • the intermediate heat exchanger 7 is brought into a state of functioning as a cooler, and the second suction return on / off valve 92a of the second suction return pipe 92 is closed, whereby the intermediate heat exchanger 7 and the compression mechanism 2 are closed.
  • the suction side is not connected (except during the cooling start control), and the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94 is closed, whereby the use side heat exchange is performed.
  • the heat exchanger 6 and the heat source side heat exchanger 4 are not connected to the intermediate heat exchanger 7.
  • the low-pressure refrigerant (see point A in FIGS. 14 to 16) is sucked into the compression mechanism 2 from the suction pipe 2a and first compressed to an intermediate pressure by the compression element 2c, It is discharged into the refrigerant pipe 8 (see point B1 in FIGS. 14 to 16).
  • the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c is cooled by exchanging heat with water or air as a cooling source in the intermediate heat exchanger 7 (point C1 in FIGS. 14 to 16). reference).
  • the refrigerant cooled in the intermediate heat exchanger 7 is further cooled by joining with the refrigerant (see point K in FIGS.
  • the high-pressure refrigerant discharged from the compression mechanism 2 flows into the oil separator 41a constituting the oil separation mechanism 41, and the accompanying refrigeration oil is separated.
  • the refrigerating machine oil separated from the high-pressure refrigerant in the oil separator 41a flows into the oil return pipe 41b constituting the oil separation mechanism 41, and is compressed after being reduced in pressure by the pressure reduction mechanism 41c provided in the oil return pipe 41b. It is returned to the suction pipe 2a of the mechanism 2 and again sucked into the compression mechanism 2.
  • the high-pressure refrigerant after the refrigerating machine oil is separated in the oil separation mechanism 41 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator through the check mechanism 42 and the switching mechanism 3. Then, the high-pressure refrigerant sent to the heat source side heat exchanger 4 is cooled by exchanging heat with water or air as a cooling source in the heat source side heat exchanger 4 (point E in FIGS. 14 to 16). reference).
  • the high-pressure refrigerant cooled in the heat source side heat exchanger 4 flows into the receiver inlet pipe 18 a through the inlet check valve 17 a of the bridge circuit 17, and a part thereof is branched to the first second-stage injection pipe 19. .
  • the refrigerant flowing through the first second-stage injection pipe 19 is reduced to near the intermediate pressure at the first second-stage injection valve 19a, and then sent to the economizer heat exchanger 20 (see point J in FIGS. 14 to 16). . Further, the refrigerant branched into the first second-stage injection pipe 19 flows into the economizer heat exchanger 20, and is cooled by exchanging heat with the refrigerant flowing through the first second-stage injection pipe 19 (FIG. 14 to FIG. 14). (See point H in FIG. 16). On the other hand, the refrigerant flowing through the first rear-stage injection pipe 19 is heated by exchanging heat with the high-pressure refrigerant cooled in the heat source-side heat exchanger 4 as a radiator (see point K in FIGS.
  • the refrigerant is joined to the intermediate-pressure refrigerant discharged from the preceding compression element 2c. Then, the high-pressure refrigerant cooled in the economizer heat exchanger 20 is decompressed to the vicinity of the saturation pressure by the first expansion mechanism 5a and temporarily stored in the receiver 18 (see point I in FIG. 14). Then, the refrigerant stored in the receiver 18 is sent to the receiver outlet pipe 18b and is decompressed by the second expansion mechanism 5b to become a low-pressure gas-liquid two-phase refrigerant, and the outlet check valve 17c of the bridge circuit 17 is used.
  • the use-side heat exchanger 6 that functions as a refrigerant evaporator (see point F in FIGS. 14 to 16). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 is heated by exchanging heat with water or air as a heating source and evaporated (see FIGS. 14 to 14). 16 point A). Then, the low-pressure refrigerant heated in the use side heat exchanger 6 is again sucked into the compression mechanism 2 via the switching mechanism 3. In this way, the cooling operation is performed.
  • the intermediate heat exchanger 7 is made into the state which functions as a cooler in the air_conditionaing
  • the heat radiation loss in the heat source side heat exchanger 4 can be reduced.
  • the first rear-stage injection pipe 19 and the economizer heat exchanger 20 are provided to branch the refrigerant sent from the heat source-side heat exchanger 4 to the expansion mechanisms 5a and 5b, thereby compressing the rear-stage compression element.
  • the temperature of the refrigerant sucked into the compression element 2d on the rear stage side can be further reduced without performing heat radiation to the outside like the intermediate heat exchanger 7 (FIG. 16). (See points C1 and G). Thereby, the temperature of the refrigerant discharged from the compression mechanism 2 is further suppressed (see points D and D ′ in FIG. 16), and compared with the case where the first second-stage injection pipe 19 is not provided, the point in FIG. Since the heat dissipation loss corresponding to the area surrounded by connecting C1, D ′, D, and G can be further reduced, the operating efficiency can be further improved.
  • the refrigerant discharged from the compression element 2c on the front stage side through the intermediate heat exchanger bypass pipe 9 at the start of the cooling operation in which the switching mechanism 3 is in the cooling operation state Is sucked into the compression element 2d on the rear stage side, and the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected through the second suction return pipe 92, so that the switching mechanism 2 is brought into the cooling operation state. Even if liquid refrigerant has accumulated in the intermediate heat exchanger 7 before the start of operation, the liquid refrigerant can be extracted out of the intermediate heat exchanger 7, whereby the switching mechanism 3 is brought into the cooling operation state.
  • the state in which the liquid refrigerant has accumulated in the intermediate heat exchanger 7 can be avoided, and the latter-stage compression element caused by the liquid refrigerant having accumulated in the intermediate heat exchanger 7 Hydraulic pressure at 2d It is no longer occurs, it is possible to improve the reliability of the compression mechanism 2.
  • the switching mechanism 3 is in a heating operation state indicated by a broken line in FIG.
  • the opening degree of the first expansion mechanism 5a and the second expansion mechanism 5b is adjusted. Further, the opening degree of the first second-stage injection valve 19a is adjusted in the same manner as in the above-described cooling operation. Since the switching mechanism 3 is in a heating operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is closed, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is opened. As a result, the intermediate heat exchanger 7 does not function as a cooler.
  • the switching mechanism 3 since the switching mechanism 3 is in the heating operation state, the state where the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected by opening the second suction return on / off valve 92a of the second suction return pipe 92.
  • the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94 between the use side heat exchanger 6 and the heat source side heat exchanger 4, the intermediate heat exchanger 7 and Is connected.
  • the low-pressure refrigerant (see point A in FIGS. 14, 17, and 18) is sucked into the compression mechanism 2 from the suction pipe 2a and first compressed to an intermediate pressure by the compression element 2c. Later, it is discharged into the intermediate refrigerant pipe 8 (see point B1 in FIGS. 14, 17, and 18). Unlike the cooling operation, the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c does not pass through the intermediate heat exchanger 7 (that is, is not cooled), and the intermediate heat exchanger bypass pipe. 9 (see point C1 in FIGS.
  • the refrigerant is returned from the first rear-stage injection pipe 19 to the rear-stage compression mechanism 2d (point K in FIGS. 14, 17, and 18). (Refer to point G in FIGS. 14, 17, and 18).
  • the intermediate pressure refrigerant combined with the refrigerant returning from the first second-stage injection pipe 19 is sucked into the compression element 2d connected to the second-stage side of the compression element 2c and further compressed, and is discharged from the compression mechanism 2 to the discharge pipe. 2b (see point D in FIGS. 14, 17 and 18).
  • the high-pressure refrigerant discharged from the compression mechanism 2 is subjected to the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG.
  • the high-pressure refrigerant after the refrigerating machine oil is separated in the oil separation mechanism 41 is sent to the use side heat exchanger 6 functioning as a refrigerant radiator through the check mechanism 42 and the switching mechanism 3 to be cooled. It cools by performing heat exchange with water or air as a source (see point F in FIGS. 14, 17, and 18). Then, the high-pressure refrigerant cooled in the use side heat exchanger 6 flows into the receiver inlet pipe 18a through the inlet check valve 17b of the bridge circuit 17, and a part thereof is branched to the first second-stage injection pipe 19. .
  • the refrigerant flowing through the first rear-stage injection pipe 19 is heated by exchanging heat with the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator (see FIGS. 14, 17, and 18).
  • the refrigerant merges with the intermediate pressure refrigerant discharged from the preceding compression element 2c.
  • the high-pressure refrigerant cooled in the economizer heat exchanger 20 is decompressed to the vicinity of the saturation pressure by the first expansion mechanism 5a and temporarily stored in the receiver 18 (see point I in FIG. 14).
  • the refrigerant stored in the receiver 18 is sent to the receiver outlet pipe 18b and is reduced in pressure by the second expansion mechanism 5b to become a low-pressure gas-liquid two-phase refrigerant, and the outlet check valve 17d of the bridge circuit 17 is supplied.
  • the intermediate heat exchanger return pipe 94 and also to the intermediate heat exchanger 7 functioning as the refrigerant evaporator (FIGS. 14 and FIG. 14). 17, see point E in FIG.
  • the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 is heated and exchanged with water or air as a heating source to evaporate (FIG. 14, FIG. 17, see point A in FIG.
  • the low-pressure gas-liquid two-phase refrigerant sent to the intermediate heat exchanger 7 is also heated by exchanging heat with water or air as a heating source (FIGS. 14 and 17). , See point V in FIG. 18).
  • the low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 is again sucked into the compression mechanism 2 via the switching mechanism 3.
  • the low-pressure refrigerant heated and evaporated in the intermediate heat exchanger 7 is again sucked into the compression mechanism 2 through the second suction return pipe 92. In this way, the heating operation is performed.
  • the temperature of the refrigerant sucked into the second-stage compression element 2d is further reduced without performing heat radiation to the outside like the intermediate heat exchanger 7 because the second-stage compression element 2d is returned to the second-stage compression element 2d. (See points B1 and G in FIG. 18).
  • the temperature of the refrigerant discharged from the compression mechanism 2 is further suppressed (see points D and D ′ in FIG. 18), and compared with the case where the first second-stage injection pipe 19 is not provided, the point in FIG. Since the heat dissipation loss corresponding to the area surrounded by connecting B1, D ′, D, and G can be reduced, the operating efficiency can be further improved.
  • the heat radiation loss in the heat source side heat exchanger 4 that functions as a refrigerant radiator is reduced, and the operation efficiency during the cooling operation is improved.
  • the intermediate heat exchanger 7 is effectively used, and the heating capacity in the use-side heat exchanger 4 is suppressed from being lowered, so that the operation efficiency during the heating operation is not lowered. It is possible to do so.
  • the heat exchanger having a flow path that flows so that the refrigerant flowing through the rear-stage-side injection pipe 19 is opposed to the heat-source-side heat exchanger 4 or the utilization-side heat exchanger 6 in the economizer heat exchanger 20 is adopted.
  • the temperature difference between the refrigerant sent to the expansion mechanisms 5a and 5b and the refrigerant flowing through the rear-stage injection pipe 19 can be reduced, and high heat exchange efficiency can be obtained.
  • the configuration includes a plurality of usage-side heat exchangers 6 connected in parallel to each other, and each usage-side heat exchanger
  • each usage-side heat exchanger In order to obtain the refrigeration load required in each use side heat exchanger 6 by controlling the flow rate of the refrigerant flowing through the receiver 6, the receiver 18 as a gas-liquid separator and the use side heat exchanger 6 can be obtained.
  • the use side expansion mechanism 5c may be provided so as to correspond to each use side heat exchanger 6.
  • the refrigerant circuit 210 see FIG.
  • the first expansion mechanism 5a as the heat source side expansion mechanism after being cooled in the heat source side heat exchanger 4 as the radiator like the cooling operation in which the switching mechanism 3 is in the cooling operation state.
  • the intermediate pressure by the economizer heat exchanger 20 is the same as in the third modification. Injection is advantageous.
  • each use-side expansion mechanism 5c is used as a radiator so that the refrigeration load required in each use-side heat exchanger 6 as a radiator can be obtained.
  • the flow rate of the refrigerant flowing through each usage-side heat exchanger 6 is controlled, and the flow rate of the refrigerant passing through each usage-side heat exchanger 6 as a radiator is the same as that of each usage-side heat exchanger 6 as a radiator.
  • the opening degree control of each use side expansion mechanism 5c is performed.
  • the degree of decompression of the refrigerant varies depending not only on the flow rate of the refrigerant flowing through each use side heat exchanger 6 as a radiator but also on the state of flow distribution among the use side heat exchangers 6 as a plurality of radiators.
  • Multiple use-side swelling Since the degree of decompression may vary greatly between the mechanisms 5c, or the degree of decompression in the use-side expansion mechanism 5c may be relatively large, the refrigerant pressure at the inlet of the economizer heat exchanger 20 becomes low. In such a case, the amount of heat exchanged in the economizer heat exchanger 20 (i.e., the flow rate of the refrigerant flowing through the first second-stage injection pipe 19) may be reduced, making it difficult to use.
  • a heat source unit mainly including the compression mechanism 2, the heat source side heat exchanger 4 and the receiver 18 and a utilization unit mainly including the utilization side heat exchanger 6 are connected by a communication pipe.
  • this connection pipe may be very long depending on the arrangement of the utilization unit and the heat source unit. Therefore, the influence of the pressure loss is also added, and the economizer heat exchanger 20 The refrigerant pressure at the inlet of the refrigerant will further decrease.
  • the receiver 18 in order to allow the receiver 18 to function as a gas-liquid separator and perform intermediate pressure injection, the receiver 18 is provided with a second second-stage injection pipe 18c.
  • the refrigerant circuit 310 is capable of performing intermediate pressure injection by the economizer heat exchanger 20 during cooling operation and performing intermediate pressure injection by the receiver 18 as a gas-liquid separator during heating operation.
  • the second second-stage injection pipe 18c is a refrigerant pipe that can perform intermediate pressure injection by extracting the refrigerant from the receiver 18 and returning it to the second-stage compression element 2d of the compression mechanism 2.
  • the second second-stage injection pipe 18c is provided with a second second-stage injection on-off valve 18d and a second second-stage injection check mechanism 18e.
  • the second second-stage injection on / off valve 18d is a valve that can be opened and closed, and is an electromagnetic valve in this modification.
  • the second second-stage injection check mechanism 18e allows the refrigerant flow from the receiver 18 to the second-stage compression element 2d and blocks the refrigerant flow from the second-stage compression element 2d to the receiver 18. This is a mechanism, and a check valve is used in this modification.
  • the second rear injection pipe 18c and the first suction return pipe 18f are integrated with each other on the receiver 18 side. Further, the second rear-stage injection pipe 18c and the first rear-stage injection pipe 19 are integrally formed on the intermediate refrigerant pipe 8 side.
  • the use side expansion mechanism 5c is an electric expansion valve.
  • the first second-stage injection pipe 19 and the economizer heat exchanger 20 are used during the cooling operation, and the second second-stage injection pipe 18c is used during the heating operation. Therefore, since it is not necessary to make the flow direction of the refrigerant to the economizer heat exchanger 20 constant regardless of the cooling operation and the heating operation, the bridge circuit 17 is omitted and the configuration of the refrigerant circuit 310 is simplified.
  • FIG. 20 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the heating operation
  • FIG. 21 is a temperature-entropy diagram illustrating the refrigeration cycle during the heating operation.
  • operation control including cooling start control not described here
  • heating operation is performed by the control unit (not shown) in the above-described embodiment.
  • high pressure means high pressure in the refrigeration cycle (that is, pressure at points D, D ′, E, and H in FIGS. 15 and 16, and points D, D ′, and FIGS. 20 and 21).
  • Pressure in F means "low pressure” means low pressure in the refrigeration cycle (that is, pressure at points A and F in FIGS. 15 and 16 and pressure at points A, E and V in FIGS. 20 and 21).
  • intermediate pressure means an intermediate pressure in the refrigeration cycle (that is, points B1, C1, G, J, K in FIGS. 15 and 16 and points B1, C1, G, I, L, FIGS. 20 and 21). Pressure at M).
  • the switching mechanism 3 is in the cooling operation state indicated by the solid line in FIG.
  • the opening degree of the first expansion mechanism 5a and the use-side expansion mechanism 5c as the heat source side expansion mechanism is adjusted. Since the switching mechanism 3 is in the cooling operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is opened, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is closed. Thus, the intermediate heat exchanger 7 is brought into a state of functioning as a cooler, and the second suction return on / off valve 92a of the second suction return pipe 92 is closed, whereby the intermediate heat exchanger 7 and the compression mechanism 2 are closed.
  • the suction side is not connected (except during the cooling start control), and the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94 is closed, whereby the use side heat exchange is performed.
  • the heat exchanger 6 and the heat source side heat exchanger 4 are not connected to the intermediate heat exchanger 7.
  • the switching mechanism 3 when the switching mechanism 3 is in the cooling operation state, it is heated in the economizer heat exchanger 20 through the first second-stage injection pipe 19 without performing intermediate pressure injection by the receiver 18 as a gas-liquid separator.
  • the intermediate pressure injection by the economizer heat exchanger 20 for returning the refrigerant to the compression element 2d on the rear stage side is performed. More specifically, the second second-stage injection on / off valve 18d is closed, and the opening degree of the first second-stage injection valve 19a is adjusted in the same manner as in Modification 3 described above.
  • a low-pressure refrigerant (see point A in FIGS. 19, 15, and 16) is sucked into the compression mechanism 2 from the suction pipe 2a and first compressed to an intermediate pressure by the compression element 2c. Later, it is discharged into the intermediate refrigerant pipe 8 (see point B1 in FIGS. 19, 15, and 16).
  • the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c is cooled by exchanging heat with water or air as a cooling source in the intermediate heat exchanger 7 (FIGS. 19, 15, and 16). Point C1).
  • the refrigerant cooled in the intermediate heat exchanger 7 joins with the refrigerant (see point K in FIGS.
  • the high-pressure refrigerant discharged from the compression mechanism 2 is compressed to a pressure exceeding the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 15) by the two-stage compression operation by the compression elements 2c and 2d.
  • the high-pressure refrigerant discharged from the compression mechanism 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator via the switching mechanism 3, and water, air, and heat as a cooling source. It replaces and it cools (refer the point E of Drawing 19, Drawing 15, and Drawing 16).
  • a part of the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator is branched to the first second-stage injection pipe 19.
  • the refrigerant flowing through the first second-stage injection pipe 19 is heated by exchanging heat with the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator (see FIGS. 19, 15, and 16).
  • the refrigerant merges with the intermediate pressure refrigerant discharged from the preceding compression element 2c.
  • the high-pressure refrigerant cooled in the economizer heat exchanger 20 is depressurized to near the saturation pressure by the first expansion mechanism 5a and temporarily stored in the receiver 18 (point I in FIGS. 19, 15, and 16). reference).
  • the refrigerant stored in the receiver 18 is sent to the use-side expansion mechanism 5c, and is decompressed by the use-side expansion mechanism 5c to become a low-pressure gas-liquid two-phase refrigerant, which functions as a refrigerant evaporator. It is sent to the side heat exchanger 6 (see point F in FIGS. 19, 15 and 16). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point A in FIGS. 19, 15 and 16). Then, the low-pressure refrigerant heated and evaporated in the use side heat exchanger 6 as the evaporator is again sucked into the compression mechanism 2 via the switching mechanism 3. In this way, the cooling operation is performed.
  • the switching mechanism 3 is in a heating operation state indicated by a broken line in FIG.
  • the opening degree of the first expansion mechanism 5a and the use-side expansion mechanism 5c as the heat source side expansion mechanism is adjusted. Since the switching mechanism 3 is in a heating operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is closed, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is opened. As a result, the intermediate heat exchanger 7 does not function as a cooler.
  • the switching mechanism 3 since the switching mechanism 3 is in the heating operation state, the state where the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected by opening the second suction return on / off valve 92a of the second suction return pipe 92. In addition, by opening the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94, between the use side heat exchanger 6 and the heat source side heat exchanger 4, the intermediate heat exchanger 7 and Is connected. Further, when the switching mechanism 3 is in the heating operation state, the intermediate pressure injection by the economizer heat exchanger 20 is not performed, and the refrigerant is supplied from the receiver 18 as the gas-liquid separator through the second rear-stage injection pipe 18c. Intermediate pressure injection is performed by the receiver 18 that returns to the compression element 2d on the rear stage side. More specifically, the second second-stage injection on / off valve 18d is opened, and the first second-stage injection valve 19a is fully closed.
  • low-pressure refrigerant (see point A in FIGS. 19 to 21) is sucked into the compression mechanism 2 from the suction pipe 2a, and first compressed to an intermediate pressure by the compression element 2c, The refrigerant is discharged into the refrigerant pipe 8 (see point B1 in FIGS. 19 to 21).
  • the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c does not pass through the intermediate heat exchanger 7 (that is, is not cooled), and the intermediate heat exchanger bypass pipe. 9 (see point C1 in FIGS. 19 to 21), and the refrigerant (see point M in FIGS.
  • the high-pressure refrigerant discharged from the compression mechanism 2 is subjected to the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 20) by the two-stage compression operation by the compression elements 2c and 2d as in the cooling operation. ) Compressed to a pressure exceeding
  • the high-pressure refrigerant discharged from the compression mechanism 2 is sent to the use-side heat exchanger 6 that functions as a refrigerant radiator via the switching mechanism 3, and water, air, and heat as a cooling source. It is exchanged and cooled (see point F in FIGS. 19 to 21).
  • the high-pressure refrigerant cooled in the use-side heat exchanger 6 as a radiator is decompressed to the vicinity of the intermediate pressure by the use-side expansion mechanism 5c, and is then temporarily stored in the receiver 18 and gas-liquid separation is performed. (See points I, L, M in FIGS. 19-21).
  • the gas refrigerant separated from the gas and liquid in the receiver 18 is extracted from the upper part of the receiver 18 by the second second-stage injection pipe 18c, and has the intermediate pressure discharged from the first-stage compression element 2c as described above. It will join the refrigerant.
  • the liquid refrigerant stored in the receiver 18 is decompressed by the first expansion mechanism 5a to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the heat source side heat exchanger 4 functioning as an evaporator of the refrigerant.
  • the refrigerant is also sent to the intermediate heat exchanger 7 functioning as a refrigerant evaporator through the intermediate heat exchanger return pipe 94 (see point E in FIGS. 19 to 21).
  • the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 is heated by exchanging heat with water or air as a heating source to evaporate (FIG. 19 to FIG. 19). (See point A on 21).
  • the low-pressure gas-liquid two-phase refrigerant sent to the intermediate heat exchanger 7 is also heated by exchanging heat with water or air as a heating source (FIGS. 19 to 21). Point V).
  • the low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 is again sucked into the compression mechanism 2 via the switching mechanism 3.
  • the low-pressure refrigerant heated and evaporated in the intermediate heat exchanger 7 is again sucked into the compression mechanism 2 through the second suction return pipe 92. In this way, the heating operation is performed.
  • this modification differs from the modification 3 in the point that instead of the intermediate pressure injection by the economizer heat exchanger 20 during the heating operation, the intermediate pressure injection by the receiver 18 as a gas-liquid separator is performed. About the point, the effect similar to the modification 3 can be acquired. Further, in this modification, switching between the cooling operation and the cooling start control, that is, switching between the refrigerant non-return state and the refrigerant return state is performed according to the open / close state of the on-off valves 11, 12, 92a.
  • an intermediate heat exchanger switching valve 93 that can switch between the refrigerant non-return state and the refrigerant return state may be provided in place of the on-off valves 11, 12, 92a as in the first modification. Furthermore, when adopting the configuration of the heat source unit 1a as in the second modification, a particularly advantageous effect can be obtained.
  • each use-side expansion mechanism 5c that is decompressed to near the saturation pressure by the first expansion mechanism 5a and temporarily accumulated in the receiver 18 is used as each use-side expansion mechanism.
  • the refrigerant sent from the receiver 18 to each use-side expansion mechanism 5c is in a gas-liquid two-phase state, there is a possibility that a drift may occur during distribution to each use-side expansion mechanism 5c. It is desirable to make the refrigerant sent from each to the use side expansion mechanism 5c as supercooled as possible.
  • the supercooling heat exchanger 96 and the third suction return pipe are provided between the receiver 18 and the use side expansion mechanism 5c.
  • the refrigerant circuit 410 is provided with 95.
  • the supercooling heat exchanger 96 is a heat exchanger that cools the refrigerant sent from the receiver 18 to the use-side expansion mechanism 5c.
  • the supercooling heat exchanger 96 branches a part of the refrigerant sent from the receiver 18 to the use-side expansion mechanism 5c during the cooling operation, so that the suction side (that is, as an evaporator) of the compression mechanism 2
  • This is a heat exchanger that performs heat exchange with the refrigerant flowing through the third suction return pipe 95 that returns to the suction pipe 2a) between the use-side heat exchanger 6 and the compression mechanism 2, and flows so that both refrigerants face each other.
  • a road a road.
  • the third suction return pipe 95 branches the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the utilization side expansion mechanism 5c and returns it to the suction side (that is, the suction pipe 2a) of the compression mechanism 2. It is a refrigerant pipe.
  • the third suction return pipe 95 is provided with a third suction return valve 95a whose opening degree can be controlled.
  • the refrigerant sent from the receiver 18 to the use side expansion mechanism 5c and the third suction return valve 95a are controlled. Heat exchange with the refrigerant flowing through the third suction return pipe 95 after the pressure is reduced to near low pressure in the three suction return valve 95a is performed.
  • the third suction return valve 95a is an electric expansion valve in this modification.
  • the suction pipe 2 a or the compression mechanism 2 is provided with a suction pressure sensor 60 that detects the pressure of the refrigerant flowing on the suction side of the compression mechanism 2.
  • a supercooling heat exchanger outlet temperature sensor 59 that detects the temperature of the refrigerant at the outlet of the supercooling heat exchanger 96 on the third suction return pipe 95 side is provided at the outlet of the supercooling heat exchanger 96 on the third suction return pipe 95 side. Is provided.
  • FIG. 23 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation
  • FIG. 24 is a temperature-entropy diagram illustrating the refrigeration cycle during the cooling operation.
  • operation control including cooling start control not described here
  • heating operation is performed by the control unit (not shown) in the above-described embodiment.
  • “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points D, E, I, and R in FIGS. 23 and 24, and points D, D ′, and F in FIGS. 20 and 21).
  • “Low pressure” means low pressure in the refrigeration cycle (that is, pressure at points A, F, F, S ', U in FIGS. 23 and 24, and points A, E,
  • “Intermediate pressure” means an intermediate pressure in the refrigeration cycle (ie, points B1, C1, G, J, K in FIGS. 23 and 24 and points B1, C1, Pressure in G, I, L, and M).
  • the switching mechanism 3 is in the cooling operation state indicated by the solid line in FIG.
  • the opening degree of the first expansion mechanism 5a and the use-side expansion mechanism 5c as the heat source side expansion mechanism is adjusted. Since the switching mechanism 3 is in the cooling operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is opened, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is closed. Thus, the intermediate heat exchanger 7 is brought into a state of functioning as a cooler, and the second suction return on / off valve 92a of the second suction return pipe 92 is closed, whereby the intermediate heat exchanger 7 and the compression mechanism 2 are closed.
  • the suction side is not connected (except during the cooling start control), and the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94 is closed, whereby the use side heat exchange is performed.
  • the heat exchanger 6 and the heat source side heat exchanger 4 are not connected to the intermediate heat exchanger 7. Further, when the switching mechanism 3 is in the cooling operation state, it is heated in the economizer heat exchanger 20 through the first second-stage injection pipe 19 without performing intermediate pressure injection by the receiver 18 as a gas-liquid separator. The intermediate pressure injection by the economizer heat exchanger 20 for returning the refrigerant to the compression element 2d on the rear stage side is performed.
  • the second second-stage injection on / off valve 18d is closed, and the opening degree of the first second-stage injection valve 19a is adjusted in the same manner as in Modification 3 described above.
  • the degree of opening of the third suction return valve 95a is also adjusted because the supercooling heat exchanger 96 is used. More specifically, in this modification, the third suction return valve 95a adjusts the opening so that the degree of superheat of the refrigerant at the outlet of the supercooling heat exchanger 96 on the third suction return pipe 95 side becomes the target value. In other words, so-called superheat control is performed.
  • the superheat degree of the refrigerant at the outlet of the supercooling heat exchanger 96 on the side of the third suction return pipe 95 is calculated by converting the low pressure detected by the suction pressure sensor 60 into a saturation temperature, and the supercooling heat exchange outlet temperature. This is obtained by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature detected by the sensor 59.
  • a temperature sensor is provided at the inlet of the third cooling return pipe 95 side of the supercooling heat exchanger 96, and the refrigerant temperature detected by this temperature sensor is used as the supercooling heat exchange outlet.
  • the degree of superheat of the refrigerant at the outlet on the third suction return pipe 95 side of the supercooling heat exchanger 96 may be obtained. Further, the adjustment of the opening degree of the third suction return valve 95a is not limited to the superheat degree control. For example, the opening degree of the third suction return valve 95a may be opened by a predetermined opening degree according to the refrigerant circulation amount in the refrigerant circuit 410. Good.
  • the low-pressure refrigerant (see point A in FIGS. 22 to 24) is sucked into the compression mechanism 2 from the suction pipe 2a and first compressed to an intermediate pressure by the compression element 2c,
  • the refrigerant is discharged into the refrigerant pipe 8 (see point B1 in FIGS. 22 to 24).
  • the intermediate-pressure refrigerant discharged from the preceding compression element 2c is cooled by exchanging heat with water or air as a cooling source in the intermediate heat exchanger 7 (point C1 in FIGS. 22 to 24). reference).
  • the refrigerant cooled in the intermediate heat exchanger 7 is further cooled by joining with the refrigerant (see point K in FIGS.
  • the intermediate-pressure refrigerant joined with the refrigerant returning from the first second-stage injection pipe 19 (that is, subjected to intermediate-pressure injection by the economizer heat exchanger 20) is compressed by being connected to the second-stage side of the compression element 2c. It is sucked into the element 2d, further compressed, and discharged from the compression mechanism 2 to the discharge pipe 2b (see point D in FIGS. 22 to 24).
  • the high-pressure refrigerant discharged from the compression mechanism 2 is compressed to a pressure exceeding the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG.
  • the high-pressure refrigerant discharged from the compression mechanism 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator via the switching mechanism 3, and water, air, and heat as a cooling source. It is exchanged and cooled (see point E in FIGS. 22 to 24).
  • a part of the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator is branched to the first second-stage injection pipe 19.
  • the refrigerant flowing through the first second-stage injection pipe 19 is sent to the economizer heat exchanger 20 after being reduced to near the intermediate pressure at the first second-stage injection valve 19a (see point J in FIGS.
  • the refrigerant branched into the first second-stage injection pipe 19 flows into the economizer heat exchanger 20, and is cooled by exchanging heat with the refrigerant flowing through the first second-stage injection pipe 19 (FIG. 20 to FIG. 20). (See point H in FIG. 22).
  • the refrigerant flowing through the first second-stage injection pipe 19 is heated by exchanging heat with the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator (see point K in FIGS. 22 to 24). ), As described above, the refrigerant is joined to the intermediate-pressure refrigerant discharged from the preceding compression element 2c.
  • the high-pressure refrigerant cooled in the economizer heat exchanger 20 is decompressed to near the saturation pressure by the first expansion mechanism 5a and is temporarily stored in the receiver 18 (see point I in FIGS. 22 to 24).
  • a part of the refrigerant stored in the receiver 18 is branched to the third suction return pipe 95.
  • the refrigerant flowing through the third suction return pipe 95 is depressurized to near low pressure in the third suction return valve 95a, and then sent to the supercooling heat exchanger 96 (see point S in FIGS. 20 to 22).
  • the refrigerant branched into the third suction return pipe 95 flows into the supercooling heat exchanger 96 and is further cooled by exchanging heat with the refrigerant flowing through the third suction return pipe 95 (FIG. 22 to FIG. 22). (See point R in FIG. 24).
  • the refrigerant flowing through the third suction return pipe 95 is heated by exchanging heat with the high-pressure refrigerant cooled in the economizer heat exchanger 20 (see point U in FIGS. 22 to 24).
  • the refrigerant flows through the suction side (here, the suction pipe 2a).
  • the refrigerant cooled in the supercooling heat exchanger 96 is sent to the use-side expansion mechanism 5c and decompressed by the use-side expansion mechanism 5c to become a low-pressure gas-liquid two-phase refrigerant, which functions as a refrigerant evaporator.
  • a low-pressure gas-liquid two-phase refrigerant which functions as a refrigerant evaporator.
  • the use side heat exchanger 6 see point F in FIGS. 22 to 24.
  • the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point A in FIGS. 22 to 24).
  • the low-pressure refrigerant heated and evaporated in the use side heat exchanger 6 as the evaporator is again sucked into the compression mechanism 2 via the switching mechanism 3. In this way, the cooling operation is performed.
  • the switching mechanism 3 is in a heating operation state indicated by a broken line in FIG.
  • the opening degree of the first expansion mechanism 5a and the use-side expansion mechanism 5c as the heat source side expansion mechanism is adjusted. Since the switching mechanism 3 is in a heating operation state, the intermediate heat exchanger on / off valve 12 of the intermediate refrigerant pipe 8 is closed, and the intermediate heat exchanger bypass on / off valve 11 of the intermediate heat exchanger bypass pipe 9 is opened. As a result, the intermediate heat exchanger 7 does not function as a cooler.
  • the switching mechanism 3 since the switching mechanism 3 is in the heating operation state, the state where the intermediate heat exchanger 7 and the suction side of the compression mechanism 2 are connected by opening the second suction return on / off valve 92a of the second suction return pipe 92. In addition, by opening the intermediate heat exchanger return on / off valve 94a of the intermediate heat exchanger return pipe 94, between the use side heat exchanger 6 and the heat source side heat exchanger 4, the intermediate heat exchanger 7 and Is connected. Further, when the switching mechanism 3 is in the heating operation state, the intermediate pressure injection by the economizer heat exchanger 20 is not performed, and the refrigerant is supplied from the receiver 18 as the gas-liquid separator through the second rear-stage injection pipe 18c.
  • Intermediate pressure injection is performed by the receiver 18 that returns to the compression element 2d on the rear stage side. More specifically, the second second-stage injection on / off valve 18d is opened, and the first second-stage injection valve 19a is fully closed. Further, when the switching mechanism 3 is in the heating operation state, the supercooling heat exchanger 96 is not used, so that the third suction return valve 95a is also fully closed.
  • the low-pressure refrigerant (see point A in FIGS. 22, 20, and 21) is sucked into the compression mechanism 2 from the suction pipe 2a and first compressed to an intermediate pressure by the compression element 2c. Later, it is discharged into the intermediate refrigerant pipe 8 (see point B1 in FIGS. 22, 20, and 21). Unlike the cooling operation, the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c does not pass through the intermediate heat exchanger 7 (that is, is not cooled), and the intermediate heat exchanger bypass pipe. 9 (see point C1 in FIGS.
  • the refrigerant is returned from the receiver 18 to the second-stage compression mechanism 2d through the second second-stage injection pipe 18c (FIGS. 22, 20, and 21). (See point M in FIG. 22) and cooling (see point G in FIGS. 22, 20, and 21).
  • the intermediate-pressure refrigerant that has joined the refrigerant returning from the second latter-stage injection pipe 18c (that is, the intermediate-pressure injection by the receiver 18 as a gas-liquid separator) is connected to the latter-stage side of the compression element 2c. It is sucked into the compressed element 2d, further compressed, and discharged from the compression mechanism 2 to the discharge pipe 2b (see point D in FIGS. 22, 20, and 21).
  • the high-pressure refrigerant discharged from the compression mechanism 2 is subjected to the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 20) by the two-stage compression operation by the compression elements 2c and 2d as in the cooling operation. ) Compressed to a pressure exceeding
  • the high-pressure refrigerant discharged from the compression mechanism 2 is sent to the use-side heat exchanger 6 that functions as a refrigerant radiator via the switching mechanism 3, and water, air, and heat as a cooling source. It replaces and it cools (refer point F of Drawing 22, Drawing 20, and Drawing 21).
  • the high-pressure refrigerant cooled in the use-side heat exchanger 6 as a radiator is decompressed to the vicinity of the intermediate pressure by the use-side expansion mechanism 5c, and is then temporarily stored in the receiver 18 and gas-liquid separation is performed. (See points I, L, and M in FIGS. 22, 20, and 21).
  • the gas refrigerant separated from the gas and liquid in the receiver 18 is extracted from the upper part of the receiver 18 by the second second-stage injection pipe 18c, and has the intermediate pressure discharged from the first-stage compression element 2c as described above. It will join the refrigerant.
  • the liquid refrigerant stored in the receiver 18 is decompressed by the first expansion mechanism 5a to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the heat source side heat exchanger 4 functioning as an evaporator of the refrigerant. Then, it is also sent to the intermediate heat exchanger 7 functioning as a refrigerant evaporator through the intermediate heat exchanger return pipe 94 (see point E in FIGS. 22, 20, and 21). Then, the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 is heated by exchanging heat with water or air as a heating source to evaporate (FIG. 22, FIG. 20, see point A in FIG.
  • the low-pressure gas-liquid two-phase refrigerant sent to the intermediate heat exchanger 7 is also heated by exchanging heat with water or air as a heating source (FIGS. 22 and 20). , See point V in FIG. 21).
  • the low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 is again sucked into the compression mechanism 2 via the switching mechanism 3.
  • the low-pressure refrigerant heated and evaporated in the intermediate heat exchanger 7 is again sucked into the compression mechanism 2 through the second suction return pipe 92. In this way, the heating operation is performed.
  • a multistage compression mechanism may be configured by connecting in series a plurality of compressors incorporating a compression element and / or a plurality of compressors incorporating a plurality of compression elements.
  • parallel multistage compression in which two or more multistage compression type compression mechanisms are connected in parallel.
  • a compression mechanism of the type may be adopted.
  • the refrigerant circuit 510 may employ a compression mechanism 102 connected to the refrigerant circuit.
  • the first compression mechanism 103 includes a compressor 29 that compresses the refrigerant in two stages with two compression elements 103c and 103d.
  • the first suction mechanism 103 is branched from the suction mother pipe 102a of the compression mechanism 102.
  • the branch pipe 103a and the first discharge branch pipe 103b that joins the discharge mother pipe 102b of the compression mechanism 102 are connected.
  • the second compression mechanism 104 includes the compressor 30 that compresses the refrigerant in two stages with the two compression elements 104c and 104d, and the second suction mechanism branched from the suction mother pipe 102a of the compression mechanism 102.
  • the branch pipe 104a and the second discharge branch pipe 104b joined to the discharge mother pipe 102b of the compression mechanism 102 are connected. Since the compressors 29 and 30 have the same configuration as that of the compressor 21 in the above-described embodiment and its modifications, the reference numerals indicating the parts other than the compression elements 103c, 103d, 104c, and 104d are the 29th and 30th, respectively. The description will be omitted here, with a replacement for the base.
  • the compressor 29 sucks the refrigerant from the first suction branch pipe 103a, and after discharging the sucked refrigerant by the compression element 103c, discharges the refrigerant to the first inlet side intermediate branch pipe 81 constituting the intermediate refrigerant pipe 8.
  • the refrigerant discharged to the first inlet-side intermediate branch pipe 81 is sucked into the compression element 103d through the intermediate mother pipe 82 and the first outlet-side intermediate branch pipe 83 constituting the intermediate refrigerant pipe 8, and the refrigerant is further compressed. It is configured to discharge to one discharge branch pipe 103b.
  • the compressor 30 sucks the refrigerant from the first suction branch pipe 104a, compresses the sucked refrigerant by the compression element 104c, and then discharges the refrigerant to the second inlet side intermediate branch pipe 84 constituting the intermediate refrigerant pipe 8.
  • the refrigerant discharged to the two inlet side intermediate branch pipes 84 is sucked into the compression element 104d through the intermediate mother pipe 82 and the second outlet side intermediate branch pipe 85 constituting the intermediate refrigerant pipe 8, and further compressed, so that the second discharge is performed. It is comprised so that it may discharge to the branch pipe 104b.
  • the intermediate refrigerant pipe 8 is configured so that the refrigerant discharged from the compression elements 103c and 104c connected to the upstream side of the compression elements 103d and 104d is compressed by the compression element 103d connected to the downstream side of the compression elements 103c and 104c.
  • 104 d is a refrigerant pipe for inhalation, and mainly a first inlet side intermediate branch pipe 81 connected to the discharge side of the compression element 103 c on the front stage side of the first compression mechanism 103, and a front stage of the second compression mechanism 104.
  • a second inlet side intermediate branch pipe 84 connected to the discharge side of the compression element 104c on the side, an intermediate mother pipe 82 where both the inlet side intermediate branch pipes 81 and 84 merge, and a first branch branched from the intermediate mother pipe 82.
  • a first outlet side intermediate branch pipe 83 connected to the suction side of the compression element 103d on the rear stage side of the compression mechanism 103, and a suction element of the compression element 104d on the rear stage side of the second compression mechanism 104 branched from the intermediate mother pipe 82.
  • a second outlet-side intermediate branch tube 85 connected to the.
  • the discharge mother pipe 102b is a refrigerant pipe for sending the refrigerant discharged from the compression mechanism 102 to the switching mechanism 3.
  • the first discharge branch pipe 103b connected to the discharge mother pipe 102b has a first oil separation.
  • a mechanism 141 and a first check mechanism 142 are provided, and a second oil separation mechanism 143 and a second check mechanism 144 are provided in the second discharge branch pipe 104b connected to the discharge mother pipe 102b.
  • the first oil separation mechanism 141 is a mechanism that separates the refrigeration oil accompanying the refrigerant discharged from the first compression mechanism 103 from the refrigerant and returns it to the suction side of the compression mechanism 102, and is mainly discharged from the first compression mechanism 103.
  • the first oil separator 141a that separates the refrigeration oil accompanying the refrigerant to be cooled from the refrigerant, and the first oil separator that is connected to the first oil separator 141a and returns the refrigeration oil separated from the refrigerant to the suction side of the compression mechanism 102 And an oil return pipe 141b.
  • the second oil separation mechanism 143 is a mechanism that separates the refrigeration oil accompanying the refrigerant discharged from the second compression mechanism 104 from the refrigerant and returns it to the suction side of the compression mechanism 102, and is mainly discharged from the second compression mechanism 104.
  • a second oil separator 143a that separates the refrigeration oil accompanying the refrigerant from the refrigerant, and a second oil separator that is connected to the second oil separator 143a and returns the refrigeration oil separated from the refrigerant to the suction side of the compression mechanism 102.
  • an oil return pipe 143b In this modification, the first oil return pipe 141b is connected to the second suction branch pipe 104a, and the second oil return pipe 143c is connected to the first suction branch pipe 103a. For this reason, the refrigerant discharged from the first compression mechanism 103 is caused by a deviation between the amount of the refrigerating machine oil accumulated in the first compression mechanism 103 and the amount of the refrigerating machine oil accumulated in the second compression mechanism 104.
  • the amount of refrigerating machine oil in the compression mechanisms 103 and 104 is A large amount of refrigeration oil returns to the smaller one, so that the bias between the amount of refrigeration oil accumulated in the first compression mechanism 103 and the amount of refrigeration oil accumulated in the second compression mechanism 104 is eliminated. It has become. Further, in this modification, the first suction branch pipe 103a has a portion between the junction with the second oil return pipe 143b and the junction with the suction mother pipe 102a at the junction with the suction mother pipe 102a.
  • the second suction branch pipe 104a is configured such that the portion between the junction with the first oil return pipe 141b and the junction with the suction mother pipe 102a is the suction mother pipe. It is comprised so that it may become a downward slope toward the confluence
  • the oil return pipes 141b and 143b are provided with pressure reducing mechanisms 141c and 143c for reducing the pressure of the refrigerating machine oil flowing through the oil return pipes 141b and 143b.
  • the check mechanisms 142 and 144 allow the refrigerant flow from the discharge side of the compression mechanisms 103 and 104 to the switching mechanism 3, and block the refrigerant flow from the switching mechanism 3 to the discharge side of the compression mechanisms 103 and 104. It is a mechanism to do.
  • the compression mechanism 102 includes the two compression elements 103c and 103d, and the refrigerant discharged from the compression element on the front stage among the compression elements 103c and 103d is used as the compression element on the rear stage side.
  • the first compression mechanism 103 configured to sequentially compress the first and second compression elements 104c and 104d, and the refrigerant discharged from the compression element on the front stage of the compression elements 104c and 104d
  • the second compression mechanism 104 configured to sequentially compress with the compression element is connected in parallel.
  • the intermediate heat exchanger 7 is provided in the intermediate mother pipe 82 that constitutes the intermediate refrigerant pipe 8, and the refrigerant discharged from the compression element 103c on the front stage side of the first compression mechanism 103 and the second compression are provided. It is a heat exchanger that cools the refrigerant combined with the refrigerant discharged from the compression element 104c on the front stage side of the mechanism 104. That is, the intermediate heat exchanger 7 functions as a common cooler for the two compression mechanisms 103 and 104.
  • first inlet side intermediate branch pipe 81 constituting the intermediate refrigerant pipe 8 allows the refrigerant to flow from the discharge side of the compression element 103c on the front stage side of the first compression mechanism 103 to the intermediate mother pipe 82 side,
  • a non-return mechanism 81 a for blocking the flow of the refrigerant from the intermediate mother pipe 82 side to the discharge side of the preceding compression element 103 c is provided, and the second inlet-side intermediate branch constituting the intermediate refrigerant pipe 8 is provided.
  • the pipe 84 allows the refrigerant to flow from the discharge side of the compression element 104c on the front stage side of the second compression mechanism 103 to the intermediate mother pipe 82 side, and the compression element 104c on the front stage side from the intermediate mother pipe 82 side.
  • a check mechanism 84a is provided for blocking the flow of the refrigerant to the discharge side.
  • check valves are used as the check mechanisms 81a and 84a. For this reason, even if one of the compression mechanisms 103 and 104 is stopped, the refrigerant discharged from the compression element on the front stage side of the operating compression mechanism passes through the intermediate refrigerant pipe 8 to the front stage of the stopped compression mechanism.
  • the refrigerant discharged from the compression element on the upstream side of the operating compression mechanism passes through the compression element on the upstream side of the compression mechanism that is stopped.
  • the refrigerant oil of the stopped compression mechanism does not flow out to the suction side, so that the shortage of the refrigerating machine oil when starting the stopped compression mechanism is less likely to occur.
  • the priority of operation is provided between the compression mechanisms 103 and 104 (for example, when the first compression mechanism 103 is a compression mechanism that operates preferentially), it corresponds to the above-described stopped compression mechanism. Since this is limited to the second compression mechanism 104, only the check mechanism 84a corresponding to the second compression mechanism 104 may be provided in this case.
  • the first compression mechanism 103 is a compression mechanism that operates preferentially
  • the intermediate refrigerant pipe 8 is provided in common to the compression mechanisms 103 and 104
  • the first operating mechanism is in operation.
  • the refrigerant discharged from the upstream compression element 103c corresponding to the compression mechanism 103 is sucked into the downstream compression element 104d of the stopped second compression mechanism 104 through the second outlet side intermediate branch pipe 85 of the intermediate refrigerant pipe 8.
  • the refrigerant discharged from the compression element 103c on the front stage side of the operating first compression mechanism 103 passes through the compression element 104d on the rear stage side of the second compression mechanism 104 that is stopped.
  • an opening / closing valve 85a is provided in the second outlet-side intermediate branch pipe 85, and when the second compression mechanism 104 is stopped, the opening / closing valve 85a causes the second outlet-side intermediate branch pipe 85 to The refrigerant flow is cut off. Thereby, the refrigerant discharged from the compression element 103c on the front stage side of the first compression mechanism 103 in operation passes through the second outlet side intermediate branch pipe 85 of the intermediate refrigerant pipe 8, and the rear stage side of the stopped second compression mechanism 104.
  • the refrigerant discharged from the compression element 103c on the front stage side of the first compression mechanism 103 during operation becomes the compression element on the rear stage side of the second compression mechanism 104 that is stopped.
  • the refrigeration oil of the second compression mechanism 104 that is stopped through the discharge side of the compression mechanism 102 through 104d does not flow out, so that the refrigeration oil when starting the second compression mechanism 104 that is stopped is prevented. The shortage of is even less likely to occur.
  • an electromagnetic valve is used as the on-off valve 85a.
  • the second compression mechanism 104 is started after the first compression mechanism 103 is started. 8 is provided in common to the compression mechanisms 103 and 104, the pressure on the discharge side of the compression element 103c on the front stage side of the second compression mechanism 104 and the pressure on the suction side of the compression element 103d on the rear stage side are Starting from a state where the pressure on the suction side of the compression element 103c and the pressure on the discharge side of the compression element 103d on the rear stage side become higher, it is difficult to start the second compression mechanism 104 stably.
  • an activation bypass pipe 86 is provided to connect the discharge side of the compression element 104c on the front stage side of the second compression mechanism 104 and the suction side of the compression element 104d on the rear stage side.
  • the on-off valve 86a blocks the refrigerant flow in the startup bypass pipe 86, and the on-off valve 85a provides the second outlet-side intermediate branch pipe.
  • the refrigerant flow in 85 is interrupted, and when the second compression mechanism 104 is activated, the on-off valve 86a allows the refrigerant to flow into the activation bypass pipe 86, whereby the second compression mechanism 104
  • the starting bypass pipe 8 does not join the refrigerant discharged from the first-stage compression element 104c with the refrigerant discharged from the first-stage compression element 104c of the first compression mechanism 103.
  • the on-off valve 85a When the operating state of the compression mechanism 102 is stabilized (for example, when the suction pressure, the discharge pressure and the intermediate pressure of the compression mechanism 102 are stabilized), the on-off valve 85a The refrigerant can flow into the second outlet-side intermediate branch pipe 85, and the flow of the refrigerant in the startup bypass pipe 86 is blocked by the on-off valve 86a so that the normal cooling operation can be performed. It has become.
  • one end of the activation bypass pipe 86 is connected between the on-off valve 85a of the second outlet side intermediate branch pipe 85 and the suction side of the compression element 104d on the rear stage side of the second compression mechanism 104.
  • the other end is connected between the discharge side of the compression element 104 c on the front stage side of the second compression mechanism 104 and the check mechanism 84 a of the second inlet side intermediate branch pipe 84 to start the second compression mechanism 104.
  • the first compression mechanism 103 can be hardly affected by the intermediate pressure portion.
  • an electromagnetic valve is used as the on-off valve 86a.
  • the compression type compression mechanism 102 is configured, the refrigerant discharged from the front-stage compression element is sequentially compressed by the rear-stage compression element by connecting the compressors 22 and 23 having a single-stage compression structure in series.
  • a two-stage compression type compression mechanism may be configured.
  • the compression mechanism 2 instead of the compression mechanism 2 including the compressor 21 having the uniaxial two-stage compression structure, the compression of the single-stage compression structure is performed.
  • a refrigerant circuit 610 employing a compression mechanism 202 in which the machines 22 and 23 are connected in series may be used.
  • the compression mechanism 202 includes a compressor 22 that compresses the refrigerant with the compression element 2c as the first-stage compression element, and a compressor 22 that compresses the refrigerant with the compression element 2d as the second-stage compression element. It is configured.
  • the compressor 22 has a sealed structure in which a compressor drive motor 22b, a drive shaft 22c, and a compression element 2c are accommodated in a casing 22a.
  • the compressor drive motor 22b is connected to the drive shaft 22c.
  • the compressor 23 has a sealed structure in which a compressor drive motor 23b, a drive shaft 23c, and a compression element 2d are accommodated in a casing 23a.
  • the compressor drive motor 23b is connected to the drive shaft 23c.
  • the compression elements 2c and 2d are displacement type compression elements such as a rotary type and a scroll type in this modification.
  • the compression mechanism 202 sucks the refrigerant from the suction pipe 2 a, compresses the sucked refrigerant by the compression element 2 c of the compressor 22, discharges the refrigerant to the intermediate refrigerant pipe 8, and refrigerant discharged to the intermediate refrigerant pipe 8. Is sucked into the compression element 2d of the compressor 23 to further compress the refrigerant and then discharged to the discharge pipe 2b.
  • the operations of the air conditioner 1 of the present modification are the same as those of the above-described modification 1 except that the compression mechanism 2 is replaced with the compression mechanism 202 (FIGS. 10 and 10). 1 to FIG. 9 and the related description), the description is omitted here. Also in the configuration of the present modification, it is possible to obtain the same functions and effects as those of the first modification described above. (10) Modification 8
  • the intermediate heat exchanger return pipe 94 is provided with the intermediate heat exchanger return on / off valve 94a made of an electromagnetic valve, and is closed when the switching mechanism 3 is in the cooling operation state.
  • the switching mechanism 3 is controlled to be opened when it is in a heating operation state, but instead of the intermediate heat exchanger return on / off valve 94a, an intermediate heat exchange functioning as a refrigerant evaporator during heating operation is performed.
  • a flow rate adjusting valve may be provided so that the flow rate of the refrigerant flowing through the vessel 7 can be controlled.
  • an intermediate heat exchanger return valve 94b as a flow rate adjustment valve.
  • the refrigerant circuit 710 may be provided.
  • an electric expansion valve capable of adjusting the opening is used as the intermediate heat exchanger return valve 94b.
  • the first expansion mechanism 5a provided in the receiver inlet pipe 18a is connected to the refrigerant pipe 18h (more specifically, connecting the heat source side heat exchanger 4 and the bridge circuit 17).
  • the differential pressure before and after the intermediate heat exchanger return valve 94b is provided by providing the refrigerant pipe 18h at a portion between the branch position of the intermediate heat exchanger return pipe 94 and the heat source side heat exchanger 4).
  • the second expansion mechanism 5b provided in the receiver outlet pipe 18b is provided in the refrigerant pipe 18i connecting the bridge circuit 17 and the use side heat exchanger 6, so that the refrigerant in the receiver 18 can be obtained. Is set to an intermediate pressure in the refrigeration cycle.
  • the refrigerant flows through the refrigerant circuit 710 in the order of the first expansion mechanism 5a, the receiver 18, and the second expansion mechanism 5b via the bridge circuit 17 during the cooling operation, and the bridge circuit during the heating operation.
  • the point that the refrigerant flows through the refrigerant circuit 710 in the order of the second expansion mechanism 5b, the receiver 18, and the first expansion mechanism 5a via 17 is different from the above-described modified example 7 (in modified example 7, in the cooling operation and heating)
  • the refrigerant flows through the refrigerant circuit 610 in the order of the first expansion mechanism 5a, the receiver, and the second expansion mechanism 5b).
  • the intermediate heat exchanger return pipe 94 is provided with the intermediate heat exchanger return valve 94b as a flow rate adjustment valve, so that the refrigerant is supplied to the intermediate heat exchanger return pipe 94 during the cooling operation.
  • the intermediate heat exchanger return valve 94b as a flow rate adjustment valve
  • Modification 9 In the configuration of the above-described embodiment and its modified example, the refrigerant flowing between the heat source side heat exchanger 4 and the usage side heat exchanger 6 is interposed between the heat source side heat exchanger 4 and the usage side heat exchanger 6.
  • An expansion device that expands entropically may be provided.
  • the refrigerant circuit 710 in the above-described modified example 8, the refrigerant circuit 810 is provided with an expansion device 97 that expands the refrigerant isentropically in the receiver inlet pipe 18a. Also good.
  • the expansion device 97 moves from the heat source side heat exchanger 4 toward the use side heat exchanger 6 and from the use side heat exchanger 6 toward the heat source side heat exchanger 4.
  • a bridge circuit 17 as a rectifying circuit that rectifies the refrigerant so as to flow from the inlet of the expansion device 97.
  • a centrifugal or positive displacement expander is used as the expansion device 97.
  • the bridge circuit 17 is employed as the rectifier circuit.
  • the same function may be achieved by combining a four-way switching valve or a plurality of electromagnetic valves.
  • the refrigerant flows through the refrigerant circuit 810 in the order of the first expansion mechanism 5a, the expansion device 97, the receiver 18, and the second expansion mechanism 5b via the bridge circuit 17 serving as a rectifier circuit during the cooling operation.
  • the refrigerant flows through the refrigerant circuit 810 in the order of the second expansion mechanism 5b, the receiver 18, and the first expansion mechanism 5a via the bridge circuit 17 serving as a rectifier circuit during the heating operation, so that the cooling operation and the heating operation can be performed.
  • the expansion device 97 depressurizes the isentropic refrigerant (that is, in the cooling operation, FIGS. 3 and 4 are taken as an example).
  • the refrigerant is depressurized while the point F moves toward the low enthalpy side and the low entropy side.
  • the refrigerant is depressurized while moving to the low enthalpy side and the low entropy side), so that the coefficient of performance can be increased and the energy can be recovered, thereby further improving the operating efficiency during cooling and heating operations. Can do.
  • control is performed to increase the opening of the second expansion mechanism 5b downstream of the expansion device 97, control to open the first suction return valve 18g, or the like.
  • the decompression width in the expansion device 97 is increased by performing control to increase the opening degree of the first expansion mechanism 5a downstream of the expansion device 97 or control to open the first suction return valve 18g. You may make it aim at the improvement of driving efficiency to the maximum.
  • the receiver 18 positioned at the outlet of the expansion device 97 functions as a gas-liquid separator, and the gas-liquid separated gas-liquid separated in the receiver 18 is returned to the subsequent compression element 2d.
  • intermediate pressure injection by the receiver 18 as a gas-liquid separator may be performed during the cooling operation and the heating operation.
  • the second post-stage injection pipe 18c is connected to the receiver 18 so as to serve as a gas-liquid separator.
  • a refrigerant circuit 910 capable of performing intermediate pressure injection by 18 may be used.
  • the second second-stage injection pipe 18c is a refrigerant pipe that can perform intermediate pressure injection by extracting the refrigerant from the receiver 18 and returning it to the second-stage compression element 2d of the compression mechanism 202.
  • the upper part is provided so as to connect the intermediate refrigerant pipe 8 (that is, the suction side of the compression element 2d on the rear stage side of the compression mechanism 202).
  • the second second-stage injection pipe 18c is provided with a second second-stage injection on-off valve 18d and a second second-stage injection check mechanism 18e.
  • the second second-stage injection on / off valve 18d is a valve that can be opened and closed, and is a solenoid valve in this modification.
  • the second second-stage injection check mechanism 18e allows the refrigerant flow from the receiver 18 to the second-stage compression element 2d and blocks the refrigerant flow from the second-stage compression element 2d to the receiver 18. This is a mechanism, and a check valve is used in this modification.
  • the second rear-stage injection pipe 18c and the first suction return pipe 18f are integrated with each other on the receiver 18 side.
  • the receiver 18 connected to the outlet of the expansion device 9 functions as a gas-liquid separator in both the cooling operation and the heating operation, and the gas-liquid separation is performed in the receiver 18.
  • the intermediate pressure injection is performed to return the gas refrigerant through the second second-stage injection pipe 18c to the second-stage compression element 2d (that is, from FIG. 20 to FIG.
  • the temperature of the intermediate-pressure refrigerant in the refrigeration cycle sucked into the downstream compression element 2d can be lowered, and the operating efficiency can be further improved.
  • Modification 11 In the above-described modified examples 7 to 10, a configuration having a plurality of usage-side heat exchangers 6 connected in parallel to each other is performed for the purpose of cooling or heating according to the air-conditioning load of the plurality of conditioned spaces. It may be.
  • the refrigerant circuits 810 and 910 in the refrigerant circuits 810 and 910 (see FIGS. 28 and 29) in the above-described modified examples 9 and 10, a plurality (here, two) connected in parallel to each other.
  • the refrigerant circuits 1010 and 1110 having the use side heat exchanger 6 may be used.
  • a supercooler may be provided for the purpose of cooling the refrigerant sent to the use side heat exchanger 6 and the heat source side heat exchanger 4 so as to be in a supercooled state.
  • a supercooling heat exchanger 96 is provided in the receiver outlet pipe 18b, and the receiver inlet pipe 18a is routed through the receiver 18.
  • the refrigerant circuit 1210 may be provided with the third suction return pipe 95 provided up to the receiver outlet pipe 18b (here, the receiver 18).
  • the supercooling heat exchanger 96 is supplied from the receiver 18 to each usage-side heat exchanger 6 via a plurality of (here, two) usage-side expansion mechanisms 5c during the cooling operation, and from the receiver 18 during the heating operation.
  • the heat exchanger cools the refrigerant sent to the heat source side heat exchanger 4 and the intermediate heat exchanger 7 via the mechanism 5a and the intermediate heat exchanger return valve 94b. More specifically, the supercooling heat exchanger 96 performs heat exchange with the refrigerant flowing through the third suction return pipe 95 that returns from the receiver 18 to the suction side (that is, the suction pipe 2a) of the compression mechanism 2. It is.
  • the third suction return pipe 95 is provided with a third suction return valve 95a whose opening degree can be controlled, and is sent from the receiver 18 to the use-side expansion mechanism 5c during the cooling operation in the supercooling heat exchanger 96. Heat exchange is performed between the refrigerant and the refrigerant flowing through the third suction return pipe 95 after being reduced to near low pressure in the third suction return valve 95a, and from the receiver 18 to the first expansion mechanism 5a and the intermediate heat exchanger return valve 94b. Heat exchange is performed between the refrigerant to be sent and the refrigerant flowing through the third suction return pipe 95 after being reduced to near low pressure in the third suction return valve 95a.
  • the third suction return valve 95a is an electric expansion valve in this modification.
  • the third suction return pipe 95 and the first suction return pipe 18f are integrated with each other on the receiver 18 side.
  • the refrigerant sent from the receiver 18 to each usage-side expansion mechanism 5c during the cooling operation, and the first expansion mechanism 5a and the intermediate heat from the receiver 18 during the heating operation Since the refrigerant sent to the exchanger return valve 94b can be brought into a supercooled state (that is, the process from the point I to the point R is performed in FIGS. 23 and 24), the cooling is thereby performed.
  • the compressors 25 and 26 having a single-stage compression structure similar to the compressors 22 and 23 constituting the compression mechanism 202 27 is connected to the intermediate refrigerant pipe 8 connecting the discharge of the first-stage compressor 25 and the suction of the second-stage compressor 26 as described above.
  • An intermediate heat exchanger 7, an intermediate heat exchanger bypass pipe 9, a second suction return pipe 92, an intermediate heat exchanger switching valve 93, and an intermediate heat exchanger return valve 94 which are the same as those of the embodiment and the modified example,
  • Heat exchanger switching valve 93 and intermediate heat exchanger return valve 9 Similar intermediate heat exchanger 307 and the intermediate heat exchanger bypass tube 309, the second intake return tube 392, the intermediate heat exchanger switching valve 393, and may be provided an intermediate heat exchanger return valve 394.
  • the intermediate heat exchanger switching valves 93 and 393 are switched to the refrigerant non-return state, so that The heat exchangers 7 and 307 are supplied with an intermediate-pressure refrigerant in the refrigeration cycle (a refrigerant sent to the subsequent compression element 302d after being discharged from the previous compression element 302c, and a refrigerant discharged from the previous compression element 303c).
  • the intermediate heat exchangers 7 and 307 are made to function as a cooler of the refrigerant that is later sent to the compression element 302e on the subsequent stage, and the intermediate heat exchanger switching valves 93 and 393 are switched to the refrigerant return state during the heating operation.
  • Low-pressure refrigerant in the refrigeration cycle (although it differs from the above-described modification 11 etc. in that it functions as an evaporator of the refrigerant that dissipated heat in the use-side heat exchanger 6) Except the points, it is possible to obtain effects similar to such modification 11 described above.
  • the present invention can be used as long as it performs a multistage compression refrigeration cycle using a refrigerant operating in the supercritical region as a refrigerant. Applicable.
  • the refrigerant operating in the supercritical region is not limited to carbon dioxide, and ethylene, ethane, nitrogen oxide, or the like may be used.
  • a high operating efficiency can be obtained in a refrigeration apparatus having a refrigerant circuit configured to be capable of switching between a cooling operation and a heating operation and performing a multistage compression refrigeration cycle.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
  • Other Air-Conditioning Systems (AREA)
PCT/JP2009/053347 2008-02-29 2009-02-25 冷凍装置 Ceased WO2009107626A1 (ja)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US12/919,047 US20110005270A1 (en) 2008-02-29 2009-02-25 Refrigeration apparatus
EP09714344.0A EP2264380B1 (de) 2008-02-29 2009-02-25 Kühlvorrichtung
AU2009218270A AU2009218270B2 (en) 2008-02-29 2009-02-25 Refrigeration apparatus
CN2009801070403A CN101960235B (zh) 2008-02-29 2009-02-25 制冷装置

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2008048904 2008-02-29
JP2008-048904 2008-02-29
JP2008322497A JP5239824B2 (ja) 2008-02-29 2008-12-18 冷凍装置
JP2008-322497 2008-12-18

Publications (1)

Publication Number Publication Date
WO2009107626A1 true WO2009107626A1 (ja) 2009-09-03

Family

ID=41016017

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2009/053347 Ceased WO2009107626A1 (ja) 2008-02-29 2009-02-25 冷凍装置

Country Status (7)

Country Link
US (1) US20110005270A1 (de)
EP (1) EP2264380B1 (de)
JP (1) JP5239824B2 (de)
KR (1) KR20100121672A (de)
CN (1) CN101960235B (de)
AU (1) AU2009218270B2 (de)
WO (1) WO2009107626A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013051653A1 (ja) * 2011-10-07 2013-04-11 ダイキン工業株式会社 熱交換ユニット及び冷凍装置

Families Citing this family (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5784121B2 (ja) * 2011-06-29 2015-09-24 三菱電機株式会社 冷凍サイクル装置
JP5240332B2 (ja) * 2011-09-01 2013-07-17 ダイキン工業株式会社 冷凍装置
JP5403047B2 (ja) * 2011-12-28 2014-01-29 ダイキン工業株式会社 冷凍装置
JP5895662B2 (ja) * 2012-03-30 2016-03-30 ダイキン工業株式会社 冷凍装置
JP2013210158A (ja) * 2012-03-30 2013-10-10 Daikin Industries Ltd 冷凍装置
JP5958022B2 (ja) * 2012-03-30 2016-07-27 ダイキン工業株式会社 冷凍装置
JP5500240B2 (ja) * 2012-05-23 2014-05-21 ダイキン工業株式会社 冷凍装置
JP5644920B2 (ja) * 2012-05-23 2014-12-24 ダイキン工業株式会社 空気調和装置
JP6111655B2 (ja) * 2012-12-26 2017-04-12 ダイキン工業株式会社 冷凍装置
JP2014126284A (ja) * 2012-12-26 2014-07-07 Daikin Ind Ltd 冷凍装置
CN103604234B (zh) * 2013-11-14 2016-01-27 芜湖凯博尔高科实业有限公司 一种可替代冷却塔的冷却装置
JP6334320B2 (ja) * 2014-08-22 2018-05-30 株式会社Ｎｔｔファシリティーズ 蒸気圧縮式冷凍サイクル
GB2545827B (en) 2014-10-16 2020-06-24 Mitsubishi Electric Corp Refrigeration cycle apparatus
JP6465218B2 (ja) * 2015-11-11 2019-02-06 富士電機株式会社 排熱回収ヒートポンプ装置
US10088208B2 (en) * 2016-01-06 2018-10-02 Johnson Controls Technology Company Vapor compression system
US11105544B2 (en) * 2016-11-07 2021-08-31 Trane International Inc. Variable orifice for a chiller
CN108317772B (zh) * 2017-01-17 2021-03-09 青岛海尔新能源电器有限公司 一种补气增焓系统及家用电器
CN111164355B (zh) * 2017-10-10 2024-01-05 三菱电机株式会社 空调装置
CN110966782B (zh) * 2018-09-30 2025-01-28 广东美芝精密制造有限公司 空调系统
JP7343765B2 (ja) 2019-09-30 2023-09-13 ダイキン工業株式会社 空気調和機
JP7343764B2 (ja) 2019-09-30 2023-09-13 ダイキン工業株式会社 空気調和機
CN117043524B (zh) * 2021-03-30 2024-07-19 大金工业株式会社 热源机组及制冷装置
WO2024204767A1 (ja) * 2023-03-31 2024-10-03 ダイキン工業株式会社 冷凍サイクルシステム

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000011418A1 (en) * 1998-08-21 2000-03-02 Daikin Industries, Ltd. Refrigerating machine having gas injection circuit and gas-liquid separator
JP2004301453A (ja) * 2003-03-31 2004-10-28 Sanyo Electric Co Ltd 半密閉型多段圧縮機
JP2005265278A (ja) * 2004-03-18 2005-09-29 Daikin Ind Ltd 冷凍装置
JP2007178072A (ja) * 2005-12-28 2007-07-12 Sanden Corp 車両用空調装置
JP2007183044A (ja) * 2006-01-06 2007-07-19 Fuji Electric Retail Systems Co Ltd 冷却装置および自動販売機

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62233645A (ja) * 1986-03-31 1987-10-14 三菱電機株式会社 冷凍サイクル
JPH02309157A (ja) * 1989-05-24 1990-12-25 Matsushita Electric Ind Co Ltd 二段圧縮冷凍サイクル装置とその運転方法
JPH09145189A (ja) * 1995-11-27 1997-06-06 Sanyo Electric Co Ltd 冷凍サイクル及びその冷凍サイクルを備えた空気調和機
JPH09145188A (ja) * 1995-11-27 1997-06-06 Sanyo Electric Co Ltd 冷凍サイクル及びその冷凍サイクルを備えた空気調和機
JP2004184022A (ja) * 2002-12-05 2004-07-02 Sanyo Electric Co Ltd 冷媒サイクル装置
DE10313850B4 (de) * 2003-03-21 2009-06-04 Visteon Global Technologies, Inc., Dearborn Kältemittelkreislauf mit zweistufiger Verdichtung für einen kombinierten Kälteanlagen- und Wärmepumpenbetrieb, insbesondere für Kraftfahrzeuge
US7131294B2 (en) * 2004-01-13 2006-11-07 Tecumseh Products Company Method and apparatus for control of carbon dioxide gas cooler pressure by use of a capillary tube
KR101073501B1 (ko) * 2004-05-18 2011-10-17 삼성전자주식회사 다단운전 공기조화기
KR20060030761A (ko) * 2004-10-06 2006-04-11 삼성전자주식회사 다실형 공기조화 시스템 및 그 제어방법
JP2007232263A (ja) * 2006-02-28 2007-09-13 Daikin Ind Ltd 冷凍装置
EP2235448B1 (de) * 2007-12-26 2020-07-22 Carrier Corporation Kältemittelsystem mit zwischenkühler und flüssigkeits-/dampfinjektion

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000011418A1 (en) * 1998-08-21 2000-03-02 Daikin Industries, Ltd. Refrigerating machine having gas injection circuit and gas-liquid separator
JP2004301453A (ja) * 2003-03-31 2004-10-28 Sanyo Electric Co Ltd 半密閉型多段圧縮機
JP2005265278A (ja) * 2004-03-18 2005-09-29 Daikin Ind Ltd 冷凍装置
JP2007178072A (ja) * 2005-12-28 2007-07-12 Sanden Corp 車両用空調装置
JP2007183044A (ja) * 2006-01-06 2007-07-19 Fuji Electric Retail Systems Co Ltd 冷却装置および自動販売機

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013051653A1 (ja) * 2011-10-07 2013-04-11 ダイキン工業株式会社 熱交換ユニット及び冷凍装置
JP2013083394A (ja) * 2011-10-07 2013-05-09 Daikin Industries Ltd 熱交換ユニット及び冷凍装置
EP2770291A4 (de) * 2011-10-07 2016-02-24 Daikin Ind Ltd Wärmetauschereinheit und kühlvorrichtung

Also Published As

Publication number Publication date
CN101960235A (zh) 2011-01-26
JP2009229051A (ja) 2009-10-08
JP5239824B2 (ja) 2013-07-17
AU2009218270A1 (en) 2009-09-03
EP2264380A1 (de) 2010-12-22
CN101960235B (zh) 2013-01-02
EP2264380A4 (de) 2015-01-21
US20110005270A1 (en) 2011-01-13
KR20100121672A (ko) 2010-11-18
EP2264380B1 (de) 2018-04-04
AU2009218270B2 (en) 2011-12-22

Similar Documents

Publication Publication Date Title
JP5239824B2 (ja) 冷凍装置
JP5407173B2 (ja) 冷凍装置
JP5396831B2 (ja) 冷凍装置
JP5003440B2 (ja) 冷凍装置
JP5332604B2 (ja) 冷暖同時運転型空気調和装置
CN102016456B (zh) 冷冻装置
JP5003439B2 (ja) 冷凍装置
JP5593618B2 (ja) 冷凍装置
JP2009133585A (ja) 冷凍装置
JP5186949B2 (ja) 冷凍装置
WO2009131088A1 (ja) 冷凍装置
WO2020071299A1 (ja) 冷凍サイクル装置
JP5125611B2 (ja) 冷凍装置
JP2010112579A (ja) 冷凍装置
JP2009097847A (ja) 冷凍装置
JP5895662B2 (ja) 冷凍装置
JP2009229021A (ja) 冷凍装置
WO2020071300A1 (ja) 冷凍サイクル装置
JP2009204243A (ja) 冷凍装置
JP4468887B2 (ja) 過冷却装置及び過冷却装置を備える空気調和装置
JP5141364B2 (ja) 冷凍装置
JP7201912B2 (ja) 冷凍サイクル装置
JP2010112618A (ja) 空気調和装置
JP2009133579A (ja) 冷凍装置
JP2009133580A (ja) 冷凍装置

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 200980107040.3

Country of ref document: CN

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09714344

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 12919047

Country of ref document: US

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 20107020604

Country of ref document: KR

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 2009218270

Country of ref document: AU

WWE Wipo information: entry into national phase

Ref document number: 2009714344

Country of ref document: EP

ENP Entry into the national phase

Ref document number: 2009218270

Country of ref document: AU

Date of ref document: 20090225

Kind code of ref document: A