WO2009096372A1 - 冷凍装置 - Google Patents
冷凍装置 Download PDFInfo
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- WO2009096372A1 WO2009096372A1 PCT/JP2009/051235 JP2009051235W WO2009096372A1 WO 2009096372 A1 WO2009096372 A1 WO 2009096372A1 JP 2009051235 W JP2009051235 W JP 2009051235W WO 2009096372 A1 WO2009096372 A1 WO 2009096372A1
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- WIPO (PCT)
- Prior art keywords
- refrigerant
- compression element
- stage
- heat exchanger
- compression
- Prior art date
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- 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
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- 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
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- 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
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- 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
- F25B2313/0272—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using bridge circuits of one-way valves
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- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/04—Refrigeration circuit bypassing means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/07—Details of compressors or related parts
- F25B2400/072—Intercoolers therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/07—Details of compressors or related parts
- F25B2400/075—Details of compressors or related parts with parallel compressors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/13—Economisers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/23—Separators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/28—Means for preventing liquid refrigerant entering into the compressor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
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- 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
Definitions
- the present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus that performs a multistage compression refrigeration cycle.
- This air conditioner mainly includes a compressor having two compression elements connected in series, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. JP 2007-232263 A
- the refrigeration apparatus includes a heat source side heat exchanger, a use side heat exchanger, an intermediate cooler, and an intermediate cooler bypass pipe.
- 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. This means a configuration that includes a unit connected.
- 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 intermediate cooler is provided in an intermediate refrigerant pipe for sucking the refrigerant discharged from the compression element on the front stage side into the compression element on the rear stage side, and is discharged from the compression element on the front stage side and sucked into the compression element on the rear stage side. Functions as a refrigerant cooler.
- the intermediate cooler bypass pipe is connected to the intermediate refrigerant pipe so as to bypass the intermediate cooler.
- the refrigeration apparatus is provided with an intermediate cooler when the heat source temperature of the intermediate cooler or the outlet refrigerant temperature of the intermediate cooler is equal to or lower than the saturation temperature of the refrigerant sent from the front-stage compression element to the rear-stage compression element. Wet prevention control is performed to prevent the refrigerant from flowing into the intercooler by using a bypass pipe.
- 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
- a temperature difference between air or water as a heat source and the refrigerant becomes large, and the temperature of the discharged refrigerant increases. Since the heat dissipation loss increases, there is a problem that it is difficult to obtain high operating efficiency.
- an intermediate cooler that functions as a refrigerant cooler that is discharged from the former-stage compression element and sucked into the latter-stage compression element is used to compress the refrigerant discharged from the former-stage compression element on the latter-stage side.
- the refrigeration apparatus according to the second invention is the refrigeration apparatus according to the first invention, wherein the intermediate cooler is a heat exchanger using air as a heat source.
- the intermediate cooler is a heat exchanger using air as a heat source.
- the refrigeration apparatus is the refrigeration apparatus according to the first aspect of the present invention, wherein the intermediate cooler is a heat exchanger that uses water as a heat source.
- the supply is stopped.
- the refrigerant sucked into the compression element on the rear stage side can be prevented from becoming wet even when the temperature of the water that is the heat source of the intermediate cooler is low.
- the supply of water to the intermediate cooler is stopped in the wetness prevention control, so that the refrigerant in the intermediate cooler can be prevented from being stored in a liquid state.
- the refrigeration apparatus includes a compression mechanism, a heat source side heat exchanger, a use side heat exchanger, and an intercooler.
- 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. This means a configuration that includes a unit connected.
- 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 intermediate cooler is provided in an intermediate refrigerant pipe for sucking the refrigerant discharged from the compression element on the front stage side into the compression element on the rear stage side, and is discharged from the compression element on the front stage side and sucked into the compression element on the rear stage side. Functions as a refrigerant cooler.
- the refrigeration apparatus is provided with an intermediate cooler when the heat source temperature of the intermediate cooler or the outlet refrigerant temperature of the intermediate cooler is equal to or lower than the saturation temperature of the refrigerant sent from the front-stage compression element to the rear-stage compression element. Wet prevention control to reduce the flow rate of the water flowing through.
- “decreasing the flow rate of water flowing through the intercooler” also means “stopping the supply of water to the intercooler”.
- 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
- a temperature difference between air or water as a heat source and the refrigerant becomes large, and the temperature of the discharged refrigerant increases. Since the heat dissipation loss increases, there is a problem that it is difficult to obtain high operating efficiency.
- an intermediate cooler that functions as a refrigerant cooler that is discharged from the former-stage compression element and sucked into the latter-stage compression element is used to compress the refrigerant discharged from the former-stage compression element on the latter-stage side.
- this refrigeration apparatus when the heat source temperature of the intermediate cooler or the outlet refrigerant temperature of the intermediate cooler is equal to or lower than the saturation temperature of the refrigerant sent from the front-stage compression element to the rear-stage compression element, the intermediate cooler Wet prevention control to reduce the flow rate of water flowing through As a result, this refrigeration apparatus prevents the refrigerant sucked into the compression element at the rear stage from becoming wet even when the temperature of the water that is the heat source of the intercooler is low. Can do.
- the refrigerant in which the outlet refrigerant temperature of the intermediate cooler is further sent from the front-stage compression element to the rear-stage compression element in the moisture prevention control The flow rate of water flowing through the intercooler is controlled so as to be higher than the saturation temperature of the intermediate cooler.
- the refrigerant flows through the intermediate cooler so that the outlet refrigerant temperature of the intermediate cooler is higher than the saturation temperature of the refrigerant sent from the front-stage compression element to the rear-stage compression element.
- the flow rate of water is controlled, not only can the refrigerant sucked into the downstream compression element be prevented from becoming wet, but also the temperature of the refrigerant sucked into the downstream compression element is made as low as possible. As a result, the temperature of the refrigerant discharged from the compression element on the rear stage side can be kept low, and the power consumption of the compression mechanism can be reduced.
- a refrigeration apparatus is the refrigeration apparatus according to any one of the first to fifth aspects, wherein the refrigerant flows between the heat source side heat exchanger and the use side heat exchanger after being compressed by the compression mechanism. Is further provided with a rear-stage injection pipe for branching back to the rear-stage compression element.
- the temperature of the refrigerant sucked into the downstream compression element is further increased by intermediate injection using the rear injection pipe. Since the temperature can be kept low, the temperature of the refrigerant discharged from the compression mechanism can be further reduced, and the power consumption of the compression mechanism can be reduced.
- 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. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation in an air conditioner according to Modification 4.
- FIG. 10 is a pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation in an air conditioner according to Modification 4.
- FIG. 10 is a temperature-entropy diagram illustrating a refrigeration cycle during cooling 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 4. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5.
- Air conditioning equipment (refrigeration equipment) 2,102 Compression mechanism 4 Heat source side heat exchanger 6 Usage side heat exchanger 7 Intermediate cooler 8 Intermediate refrigerant pipe 9 Intermediate cooler bypass pipe 18c First rear stage side injection pipe 19 Second rear stage side 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 includes a refrigerant circuit 10 configured to be capable of cooling operation, and performs a two-stage compression refrigeration cycle using a refrigerant (here, carbon dioxide) that operates in a supercritical region.
- the refrigerant circuit 10 of the air conditioner 1 mainly includes a compression mechanism 2, a heat source side heat exchanger 4, an expansion mechanism 5, a use side heat exchanger 6, and an intermediate cooler 7.
- 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 is a refrigerant pipe for sucking the refrigerant 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. is there.
- the discharge pipe 2b is a refrigerant pipe for sending the refrigerant discharged from the compression mechanism 2 to the heat source side heat exchanger 4.
- the discharge pipe 2b is provided with an oil separation mechanism 41 and a check mechanism 42. ing.
- 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 flow from the discharge side of the compression mechanism 2 to the heat source side heat exchanger 4 and blocks the refrigerant flow from the heat source side heat exchanger 4 to the discharge side of the compression mechanism 2.
- a check valve is used.
- 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 heat source side heat exchanger 4 is a heat exchanger that functions as a refrigerant cooler.
- the heat source side heat exchanger 4 has one end connected to the compression mechanism 2 and the other end connected to the expansion mechanism 5.
- the heat source side heat exchanger 4 is a heat exchanger that uses air as a heat source (that is, a cooling source). The air as the heat source is supplied to the heat source side heat exchanger 4 by a heat source side fan (not shown).
- the expansion mechanism 5 is a mechanism that depressurizes the refrigerant, and an electric expansion valve is used in the present embodiment.
- One end of the expansion mechanism 5 is connected to the heat source side heat exchanger 4, and the other end is connected to the use side heat exchanger 6.
- the expansion mechanism 5 decompresses the high-pressure refrigerant cooled in the heat source side heat exchanger 4 before sending it to the use side heat exchanger 6.
- the use-side heat exchanger 6 is a heat exchanger that functions as a refrigerant heater.
- the use side heat exchanger 6 has one end connected to the expansion mechanism 5 and the other end connected to the compression mechanism 2.
- the use-side heat exchanger 6 is a heat exchanger that uses air or water as a heat source (that is, a heating source).
- the intermediate cooler 7 is a heat exchanger that is provided in the intermediate refrigerant pipe 8 and functions as a refrigerant cooler that is discharged from the preceding compression element 2c and sucked into the compression element 2d.
- the intercooler 7 is a heat exchanger that uses air as a heat source (that is, a cooling source). The air as the heat source is supplied to the intercooler 7 by a heat source side fan (not shown).
- the intermediate cooler 7 may be integrated with the heat source side heat exchanger 4.
- the heat source side fan is common to both the heat source side heat exchanger 4 and the intermediate cooler 7, so that the heat source There are also cases where air is supplied.
- the intermediate cooler 7 can be called 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 cooler bypass pipe 9 is connected to the intermediate refrigerant pipe 8 so as to bypass the intermediate cooler 7.
- the intermediate cooler bypass pipe 9 is a refrigerant pipe that limits the flow rate of the refrigerant flowing through the intermediate cooler 7.
- the intermediate cooler bypass pipe 9 is provided with an intermediate cooler bypass opening / closing valve 11.
- the intermediate cooler bypass on-off valve 11 is an electromagnetic valve in the present embodiment.
- the intermediate cooler bypass on-off valve 11 is basically closed except when a temporary operation such as wetness prevention control described later is performed.
- the intermediate refrigerant pipe 8 has a position on the intermediate cooler 7 side from the connection with the intermediate cooler bypass pipe 9 (that is, an intermediate from the connection with the intermediate cooler bypass pipe 9 on the inlet side of the intermediate cooler 7).
- a cooler on / off valve 12 is provided on a portion of the cooler 7 up to the connection portion on the outlet side.
- the cooler on / off valve 12 is a mechanism that limits the flow rate of the refrigerant flowing through the intermediate cooler 7.
- the cooler on / off valve 12 is an electromagnetic valve in the present embodiment.
- the cooler on / off valve 12 is basically opened except when a temporary operation such as wetness prevention control described later is performed.
- the cooler on / off valve 12 is provided at a position on the inlet side of the intermediate cooler 7.
- the intermediate refrigerant pipe 8 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 from the discharge side of the rear-stage compression element 2d to the front stage.
- a check mechanism 15 for blocking the flow of the refrigerant to the compression element 2c on the side is provided.
- the check mechanism 15 is a check valve in the present embodiment.
- the check mechanism 15 is provided in a portion from the outlet side of the intermediate cooler 7 of the intermediate refrigerant pipe 8 to the connection portion with the intermediate cooler bypass pipe 9.
- the air conditioning apparatus 1 is provided with various sensors.
- an intermediate cooler outlet temperature sensor 52 that detects the temperature of the refrigerant at the outlet of the intermediate cooler 7 is provided at the outlet of the intermediate cooler 7.
- the air conditioner 1 is provided with an air temperature sensor 53 that detects the temperature of air as a heat source of the intercooler 7.
- the intermediate refrigerant pipe 8 is provided with an intermediate pressure sensor 54 that detects an intermediate pressure of the compression mechanism that is the pressure of the refrigerant flowing through the intermediate refrigerant pipe 8.
- the air conditioner 1 controls the operation of each part constituting the air conditioner 1 such as the compression mechanism 2, the expansion mechanism 5, the intermediate cooler bypass on / off valve 11, and the cooler on / off valve 12, although not shown here. It has a control part.
- FIG. 2 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.
- the operation control in the following cooling operation and the anti-wetting control for preventing the refrigerant sucked into the compression element on the rear stage from being wet by the cooling in the intermediate cooler 7 are the above-described control unit (not shown). ).
- “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points D, D ′, and E in FIGS.
- low pressure means low pressure in the refrigeration cycle ( That is, it means the pressure at points A and F in FIGS. 2 and 3, and “intermediate pressure” and “compression mechanism intermediate pressure” mean intermediate pressures in the refrigeration cycle (that is, at points B1 and C1 in FIGS. Pressure).
- the opening degree of the expansion mechanism 5 is adjusted. Then, the cooler on / off valve 12 is opened, and the intermediate cooler bypass on / off valve 11 of the intermediate cooler bypass pipe 9 is closed, so that the intermediate cooler 7 functions as a cooler.
- the compression mechanism 2 is driven in the state of the refrigerant circuit 10, low-pressure refrigerant (see point A in FIGS. 1 to 3) is sucked into the compression mechanism 2 from the suction pipe 2a, and first, the intermediate pressure is compressed by the compression element 2c. And then discharged to the intermediate refrigerant pipe 8 (see point B1 in FIGS. 1 to 3).
- the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c is cooled by exchanging heat with air as a cooling source in the intermediate cooler 7 (see point C1 in FIGS. 1 to 3).
- the refrigerant cooled in the intermediate cooler 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 FIG. 1 to point 3 in FIG. 3).
- 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. 2) by the two-stage compression operation by the compression elements 2c and 2d.
- the critical pressure that is, the critical pressure Pcp at the critical point CP shown in FIG. 2
- 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 through the check mechanism 42 to the heat source side heat exchanger 4 that functions as a refrigerant cooler.
- 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. 1 to 3). reference).
- the high-pressure refrigerant cooled in the heat source-side heat exchanger 4 is decompressed by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the use-side heat exchanger 6 that functions as a refrigerant heater. (See point F in FIGS. 1 to 3).
- the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 is heated and evaporated in the use side heat exchanger 6 through heat exchange with water or air as a heating source. (Refer to point A in FIGS. 1 to 3). Then, the low-pressure refrigerant heated in the use side heat exchanger 6 is again sucked into the compression mechanism 2. In this way, the cooling operation is performed.
- the intermediate cooler 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 the cooler on / off valve 12 is provided in the cooling operation.
- the intermediate cooler 7 is not provided because the intermediate cooler 7 functions as a cooler by opening and closing the intermediate cooler bypass opening / closing valve 11 of the intermediate cooler bypass pipe 9 (this 2 and FIG. 3, the refrigeration cycle is performed in the order of point A ⁇ point B1 ⁇ point D ′ ⁇ point E ⁇ point F).
- the temperature of the refrigerant sucked decreases (see points B1 and C1 in FIG.
- the intercooler bypass pipe 9 is In this way, wetting prevention control is performed to prevent the refrigerant from flowing into the intercooler 7.
- the temperature of the air as the heat source of the intermediate cooler 7 detected by the air temperature sensor 53 is obtained by converting the compression mechanism intermediate pressure detected by the intermediate pressure sensor 54.
- the refrigerant discharged from the compression element 2c on the upstream side is opened by opening the intermediate cooler bypass on / off valve 11 of the intermediate cooler bypass pipe 9 and closing the cooler on / off valve 12.
- the refrigerant flows through the intermediate cooler bypass pipe 9 to the suction side of the downstream compression element 2 d, thereby preventing the intermediate pressure refrigerant from flowing into the intermediate cooler 7.
- moves in a supercritical region like this embodiment
- former stage side becomes high, and compression mechanism intermediate pressure becomes critical pressure (that is, 2, there may be an operating condition that exceeds the critical pressure Pcp at the critical point CP shown in FIG. 2, but in such an operating condition, not only a high-pressure refrigerant but also an intermediate-pressure refrigerant is called a saturated state.
- this wetting prevention control before determining whether the temperature of the air as the heat source is equal to or lower than the saturation temperature of the refrigerant sent from the front-stage compression element 2c to the rear-stage compression element 2d, the compression is performed. It is determined whether the mechanism intermediate pressure is lower than the critical pressure. If the compression mechanism intermediate pressure is equal to or higher than the critical pressure, the refrigerant is allowed to flow through the intermediate cooler 7 and sucked into the compression element 2d on the rear stage side.
- the temperature of the refrigerant as the heat source of the intermediate cooler 7 detected by the air temperature sensor 53 is reduced as described above. It is determined whether the temperature is equal to or lower than a saturation temperature obtained by converting the compression mechanism intermediate pressure detected by the intermediate pressure sensor 54, and the temperature of the air as the heat source of the intermediate cooler 7 is compressed.
- the intermediate temperature is equal to or lower than the saturation temperature obtained by converting the intermediate pressure
- the intermediate pressure refrigerant is prevented from flowing into the intermediate cooler 7, and the temperature of the air as the heat source of the intermediate cooler 7 is reduced to the compression mechanism.
- the temperature is higher than the saturation temperature obtained by converting the intermediate pressure, the refrigerant is allowed to flow through the intermediate cooler 7.
- the temperature of the air as the heat source of the intermediate cooler 7 is equal to or lower than the saturation temperature of the intermediate-pressure refrigerant sent from the front-stage compression element 2c to the rear-stage compression element 2d.
- the moisture prevention control is performed to prevent the refrigerant from flowing into the intermediate cooler 7 by using the intermediate cooler bypass pipe 9, the temperature of the air as the heat source of the intermediate cooler 7 is low. Even when the operating conditions are met, it is possible to prevent the refrigerant sucked into the subsequent compression element 2d from becoming wet.
- this air conditioner 1 when the temperature of the air as the heat source of the intermediate cooler 7 becomes equal to or lower than the saturation temperature of the intermediate-pressure refrigerant sent from the front-stage compression element 2c to the rear-stage compression element 2d. Since the cooler opening / closing valve 12 provided on the inlet side of the intermediate cooler 7 is closed, all the refrigerant discharged from the compression element 2c on the front stage side can flow to the intermediate cooler bypass pipe 9. The intermediate pressure refrigerant flowing through the intermediate refrigerant pipe 8 and the intermediate refrigerant pipe bypass pipe 9 can be prevented from flowing into the intermediate cooler 7 from the inlet side of the intermediate cooler 7 and collecting in the intermediate cooler 7.
- the intermediate cooler 7 is integrated with the heat source side heat exchanger 4, and the heat source side heat exchanger is provided by a heat source side fan (not shown) common to both the heat source side heat exchanger 4 and the intermediate cooler 7.
- whether or not the moisture prevention control is necessary depends on whether or not the temperature of the air as the heat source of the intermediate cooler 7 is equal to or lower than the saturation temperature of the intermediate-pressure refrigerant sent from the upstream compression element 2c to the downstream compression element 2d. Instead of determining, the temperature of the refrigerant at the outlet of the intermediate cooler 7 (here, the temperature of the refrigerant detected by the intermediate cooler outlet temperature sensor 52) is changed from the compression element 2c on the front stage side to the compression element on the rear stage side. Whether or not the moisture prevention control is necessary may be determined based on whether or not the temperature is equal to or lower than the saturation temperature of the intermediate-pressure refrigerant sent to 2d.
- a heat exchanger using air as a heat source is used as the intermediate cooler 7.
- a heat exchanger using water as a heat source may be used as the intermediate cooler 7.
- water is supplied to the intermediate cooler 7 through the intermediate cooling water pipe 14, and the temperature of water as a heat source of the intermediate cooler 7 (here, the intermediate cooler 7
- the temperature of the water supplied to the intermediate cooler 7 detected by the water temperature sensor 58 provided on the water inlet side) is sent from the compression element 2c on the front stage side to the compression element 2d on the rear stage side, and the saturation temperature of the intermediate pressure refrigerant Or the temperature of the refrigerant at the outlet of the intermediate cooler 7 (here, the temperature of the refrigerant detected by the intermediate cooler outlet temperature sensor 52) is changed from the compression element 2c on the rear stage side to the compression element on the rear stage side.
- the intermediate cooler bypass opening / closing valve 11 of the intermediate cooler bypass pipe 9 is opened and the cooler opening / closing valve is opened as in the above-described embodiment.
- the refrigerant discharged from the compression element 2 c at the front stage flows through the intermediate cooler bypass pipe 9 to the suction side of the compression element 2 d at the rear stage, and thereby the refrigerant at the intermediate pressure is supplied to the intermediate cooler 7.
- Wet prevention control may be performed so as not to flow.
- the water cooling on / off valve 14 a is provided in the intermediate cooling water pipe 14, and the intermediate pressure refrigerant does not flow to the intermediate cooler 7 using the above-described intermediate cooler bypass pipe 9.
- the water on / off valve 14a may be closed to stop the supply of water to the intercooler 7.
- the water on-off valve 14a is an electromagnetic valve capable of opening / closing control. In this case, it is further possible to prevent the refrigerant in the intermediate cooler 7 from becoming liquid and accumulating.
- the intermediate cooler 7 such as the intermediate cooler bypass pipe 9 and the cooler on / off valve 12 including the intermediate cooler bypass on / off valve 12 has an intermediate pressure refrigerant.
- Omit the configuration for performing control to prevent the wet prevention control for only the control to stop the supply of water to the intercooler 7 may be adopted.
- the flow rate of water supplied to the intercooler 7 is decreased by reducing the opening of the water on-off valve 14a.
- the refrigerant sucked into the second-stage compression element 2d is prevented from becoming wet, and the refrigerant temperature at the outlet of the intermediate cooler 7 is sent from the first-stage compression element 2c to the second-stage compression element 2d.
- Wet prevention control for controlling the flow rate of water flowing through the intercooler 7 may be employed so as to be higher than the saturation temperature of the refrigerant to be produced.
- the refrigerant sucked into the compression element 2d on the rear stage side can be prevented from becoming wet, and the compression element 2d on the rear stage side can be prevented.
- the temperature of the refrigerant sucked into the compressor can be lowered as much as possible, and thereby the temperature of the refrigerant discharged from the compression element 2d on the rear stage side can be kept low, and the power consumption of the compression mechanism 2 can be reduced.
- Modification 4 In the refrigerant circuit 10 (see FIGS. 1, 4, 5, and 6) in the above-described embodiment and its modifications, the refrigerant circuit 10 includes a single use-side heat exchanger 6 and can perform a cooling operation.
- a receiver 18 that temporarily stores the refrigerant flowing between the heat source side heat exchanger 4 and the use side heat exchanger 6, and the flow rate of the refrigerant flowing through each use side heat exchanger 6
- each use between the receiver 18 as a gas-liquid separator and the use side heat exchanger 6 Use side expansion to correspond to the side heat exchanger 6 If a mechanism 5c (e.g., in FIG.
- a structure without the second-stage injection tube 18c, 19 and economizer heat exchanger 20) is.
- the refrigerant is returned from the receiver 18 as the gas-liquid separator to the compression element 2d on the rear stage side, and discharged from the compression element 2c on the front stage side of the compression mechanism 2 to be compressed on the rear stage side.
- the intermediate pressure injection that merges with the refrigerant having the intermediate pressure of the compression mechanism sucked into the cylinder is performed, the temperature of the refrigerant discharged from the compression element 2d on the rear stage side is lowered, the power consumption of the compression mechanism 2 is reduced, and the operation efficiency is improved. It is possible to plan.
- the flow rate of the refrigerant flowing through each use side heat exchanger 6 is controlled, the flow rate of the refrigerant passing through each use side heat exchanger 6 in the heating operation is downstream of each use side heat exchanger 6.
- each use side expansion mechanism 5c is generally determined by the opening degree of the use side expansion mechanism 5c provided on the upstream side of the receiver 18. Not only the flow rate of refrigerant flowing through, but also multiple uses Depending on the flow distribution state between the heat exchangers 6, the opening degree is greatly different among the plurality of use side expansion mechanisms 5 c, or the use side expansion mechanism 5 c has a relatively small opening degree. For this reason, the gas-liquid separator pressure which is the pressure of the refrigerant
- 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 connecting pipe can be very long. In addition, the gas-liquid separator pressure will drop.
- the intermediate pressure injection by the receiver 18 as a gas-liquid separator can be used even under a condition where the pressure difference between the gas-liquid separator pressure and the compression mechanism intermediate pressure is small.
- the gas-liquid separator pressure is likely to be excessively lowered.
- the first expansion mechanism 5a (for example, described later) is used as the heat source side expansion mechanism before it is cooled in the heat source side heat exchanger 4 and then flows into the receiver 18 as a gas-liquid separator. 7 and 12 (see the first expansion mechanism 5a of FIG. 7), the heat source can be used under the condition that the pressure difference from the high pressure in the refrigeration cycle to the vicinity of the intermediate pressure in the refrigeration cycle can be used without significant pressure reduction operation.
- the second rear-stage injection pipe 19 that branches the refrigerant flowing between the side heat exchanger 4 and the first expansion mechanism 5a and returns the refrigerant to the rear-stage compression element 2d, the heat source-side heat exchanger 4, and the first expansion mechanism 5a.
- an economizer heat exchanger 20 that exchanges heat between the refrigerant flowing between the refrigerant and the refrigerant flowing through the second second-stage injection pipe 19, by heat exchange in the economizer heat exchanger 20. It is preferable that the refrigerant flowing through the second second-stage injection pipe 19 after being heated is returned to the second-stage compression element 2d (that is, intermediate pressure injection is performed by the economizer heat exchanger 20) (for example, FIG.
- the heat exchange in the economizer heat exchanger 20 is difficult when the pressure difference between the refrigerant pressure at the inlet of the economizer heat exchanger 20 and the intermediate pressure of the compression mechanism is large.
- the flow rate of the refrigerant that can be returned to the compression element 2d on the rear stage side increases and the application becomes effective. That.
- the high pressure in the refrigeration cycle exceeds the critical pressure, so the pressure difference between the high pressure and the intermediate pressure in the refrigeration cycle is even greater. Therefore, intermediate pressure injection by the economizer heat exchanger 20 is advantageous.
- the gas-liquid separator pressure rises to a pressure higher than the critical pressure, and the refrigerant in the receiver 18 as the gas-liquid separator is Since it may be difficult to separate the gas refrigerant and liquid refrigerant, the pressure difference from the high pressure in the refrigeration cycle to the vicinity of the intermediate pressure in the refrigeration cycle can be used in consideration of this point. In terms of conditions, it is preferable to use intermediate pressure injection by the economizer heat exchanger 20.
- the cooling operation and the heating operation can be switched, and a plurality of usage-side heat exchangers 6 connected in parallel to each other are provided, and each usage-side heat is provided.
- the receiver 18 as a gas-liquid separator and the user-side heat exchange
- the use side expansion mechanism 5c is provided so as to correspond to each use side heat exchanger 6 between the heat exchanger 6 and the refrigerant pressure on the downstream side of the use side expansion mechanism 5c may be lowered in the heating operation.
- the intermediate pressure injection by the receiver 18 as the gas-liquid separator is used, and in the cooling operation, the first expansion mechanism 5 as the heat source side expansion mechanism and the downstream side of the heat source side heat exchanger 4.
- the first expansion mechanism 5 as the heat source side expansion mechanism and the downstream side of the heat source side heat exchanger 4.
- the cooling operation and the heating operation are performed. While having the structure which has the switching mechanism 3 for enabling switching, and the some utilization side heat exchanger 6 connected mutually parallel, it replaces with the expansion mechanism 5, and is the 1st expansion mechanism 5a as a heat source side expansion mechanism. 5d and a use side expansion mechanism 5c as a use side expansion valve, and further, a bridge circuit 17, a receiver 18, a first second-stage injection pipe 18c, a second second-stage injection pipe 19, and an economizer heat exchange
- the refrigerant circuit 610 provided with the vessel 20 can be provided.
- the switching mechanism 3 is a mechanism for switching the flow direction of the refrigerant in the refrigerant circuit 610.
- the heat source side heat exchanger 4 is used as a refrigerant cooler compressed by the compression mechanism 2 and used.
- the side heat exchanger 6 In order for the side heat exchanger 6 to function as a heater for the refrigerant cooled in the heat source side heat exchanger 4, 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. 7, hereinafter, the state of the switching mechanism 3 is referred to as “cooling operation state”).
- Discharge side and use side heat exchanger 6 Can be connected to the suction side of the compression mechanism 2 and one end of the heat source side heat exchanger 4 (see the broken line of the switching mechanism 3 in FIG. "Heating 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 switching mechanism 3 is provided only for the compression mechanism 2, the heat source side heat exchanger 4, the expansion mechanisms 5a and 5d, the receiver 18, the use side expansion mechanism 5c, and the use side heat exchanger 6 that constitute the refrigerant circuit 610.
- the heating operation state to be circulated can be switched.
- 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 includes three check valves 17a, 17b, and 17c and a third expansion mechanism 5d as a heat source side expansion mechanism.
- 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. That is, 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 third expansion mechanism 5d is a mechanism that depressurizes the refrigerant, and constitutes a part of the bridge circuit 17.
- the outlet check valve 17c and the third expansion mechanism 5d 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. Therefore, the third expansion mechanism 5d is fully closed during the cooling operation in which the switching mechanism 3 is in the cooling operation state, and is connected to the receiver outlet in the heating operation in which the switching mechanism 3 is in the heating operation state. The refrigerant sent from the pipe 18b to the heat source side heat exchanger 4 is decompressed.
- the third expansion mechanism 5d is an electric expansion valve in this modification.
- 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 this modification.
- One end of the first expansion mechanism 5 a is connected to the heat source side heat exchanger 4 via the bridge circuit 17, and the other end is connected to the receiver 18.
- the first expansion mechanism 5a reduces the pressure of the high-pressure refrigerant cooled in the heat source side heat exchanger 4 before sending it to the use side heat exchanger 6 during the cooling operation, and uses it during the heating operation.
- the high-pressure refrigerant cooled in the side heat exchanger 6 is decompressed before being sent to the heat source side heat exchanger 4.
- the receiver inlet pipe 18a is provided with an expansion mechanism bypass valve 5e so as to bypass the first expansion mechanism 5a.
- the expansion mechanism bypass valve 5e is an electromagnetic valve in the present modification.
- the receiver 18 is a container that can temporarily store the refrigerant that has been decompressed by the first expansion mechanism 5a, and has an inlet connected to the receiver inlet pipe 18a and an outlet connected to the receiver outlet pipe 18b. Has been.
- the receiver 18 is connected to a first rear-stage injection pipe 18c and a suction return pipe 18f.
- the first post-stage injection pipe 18c and the suction return pipe 18f are integrated with each other on the receiver 18 side.
- the first 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 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 2).
- the first second-stage injection pipe 18c is provided with a first second-stage injection on / off valve 18d and a first second-stage injection check mechanism 18e.
- the first 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 first 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 suction return pipe 18f is a refrigerant pipe that can extract the refrigerant from the receiver 18 and return it to the compression element 2c on the front stage side of the compression mechanism 2.
- the upper part of the receiver 18 and the suction pipe 2a that is, It is provided so as to be connected to the suction side of the compression element 2c on the front stage side of the compression mechanism 2.
- the suction return pipe 18f is provided with a suction return on-off valve 18g.
- the suction return on-off valve 18g is a valve that can be opened and closed, and is an electromagnetic valve in this modification.
- the heat source side heat exchanger functions as a gas-liquid separator that separates the refrigerant flowing between the user-side heat exchanger 6 and the expansion mechanism 5a, 5d and the user-side expansion mechanism 5c.
- the liquid refrigerant thus separated can be returned from the upper part of the receiver 18 to the compression element 2d on the rear stage side of the compression mechanism 2 and the compression element 2c on the front stage side.
- the use side expansion mechanism 5c is provided so as to correspond to each use side heat exchanger 6 between the receiver 18 (more specifically, the bridge circuit 17) as a gas-liquid separator and the use side heat exchanger 6.
- an electric expansion valve is used.
- One end of the use side expansion mechanism 5c is connected to the receiver 18 via the bridge circuit 17, and the other end is connected to the corresponding use side heat exchanger 6.
- the use-side expansion mechanism 5c further reduces the pressure until the refrigerant is decompressed by the first expansion mechanism 5a before being sent to the use-side heat exchanger 6 during the cooling operation, and during the heating operation.
- the refrigerant that has passed through the use side heat exchanger 6 is decompressed before being sent to the receiver 18.
- the second 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 second 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 second 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 cooler 7 in the intermediate refrigerant pipe 8.
- the first rear-stage injection pipe 18c and the second rear-stage injection pipe 19 are integrated with each other on the intermediate refrigerant pipe 8 side.
- the second second-stage injection pipe 19 is provided with a second second-stage injection valve 19a capable of opening degree control. And the 2nd back
- 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 second second-stage injection pipe 19 (more specifically, a second 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 upstream 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 And a refrigerant flowing between the first expansion mechanism 5a and a refrigerant flowing through the second second-stage injection pipe 19, and a flow path through which both refrigerants face each other is provided.
- the economizer heat exchanger 20 is provided on the downstream side of the position where the second rear-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 second 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 second second-stage injection pipe 19.
- the switching mechanism 3 when the switching mechanism 3 is in the cooling operation state by the bridge circuit 17, the receiver 18, the receiver inlet pipe 18 a and the receiver outlet pipe 18 b, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 is , The inlet check valve 17a of the bridge circuit 17, the first expansion mechanism 5a of the receiver inlet pipe 18a, the receiver 18, the outlet check valve 17c of the bridge circuit 17, and the use side expansion mechanism 5c. You can send.
- 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 used on the use side expansion mechanism 5c, the inlet check valve 17b of the bridge circuit 17, the receiver inlet pipe.
- an economizer that detects the temperature of the refrigerant at the outlet of the economizer heat exchanger 20 on the second rear-stage injection pipe 19 side is provided at the outlet of the economizer heat exchanger 20 on the second rear-stage injection pipe 19 side.
- An outlet temperature sensor 55 is provided.
- the receiver inlet pipe 18a is provided with a gas-liquid separator temperature sensor 57 that detects the temperature of the refrigerant in the receiver 18 at a position closer to the receiver 18 than the first expansion mechanism 5a.
- the gas-liquid separator temperature sensor 57 may be provided on the receiver outlet pipe 18b, or may be provided directly on the receiver 18 like the bottom of the receiver 18, for example.
- FIG. 8 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation in the present modification
- FIG. 9 is a temperature-entropy illustrating the refrigeration cycle during the cooling operation in the present modification.
- FIG. 10 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the heating operation in the present variation
- FIG. 11 illustrates the temperature illustrating the refrigeration cycle during the heating operation in the present variation. -Entropy diagram.
- “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points D, D ′, E, and H in FIGS. 8 and 9 and points D, D ′, F, and FIGS. 10 and 11).
- Pressure at H and “low pressure” means low pressure in the refrigeration cycle (ie, pressure at points A and F in FIGS. 8 and 9 and pressure at points A and E in FIGS. 10 and 11).
- intermediate pressure means an intermediate pressure in the refrigeration cycle (that is, pressure at points B1, C1, and G in FIGS. 8 to 11).
- the switching mechanism 3 is in a cooling operation state indicated by a solid line in FIG.
- the opening degree of the first expansion mechanism 5a as the heat source side expansion mechanism and the utilization side expansion mechanism 5c as the utilization side expansion valve are adjusted.
- the third expansion mechanism 5d and the expansion mechanism bypass valve 5e are fully closed.
- the switching mechanism 3 is heated in the economizer heat exchanger 20 through the second 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 first second-stage injection on / off valve 18d is closed, and the opening degree of the second second-stage injection valve 19a is adjusted.
- the second rear-stage injection valve 19a is so-called superheat degree control whose opening degree is adjusted so that the degree of superheat of the refrigerant at the outlet of the economizer heat exchanger 20 on the second rear-stage injection pipe 19 side becomes a target value.
- the superheat degree of the refrigerant at the outlet of the economizer heat exchanger 20 on the second post-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.
- a temperature sensor is provided at the inlet of the economizer heat exchanger 20 on the second rear-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 second rear-stage injection pipe 19 side may be obtained by subtracting from the refrigerant temperature detected by the above. Further, the cooler on / off valve 12 is opened, and the intermediate cooler bypass on / off valve 11 of the intermediate cooler bypass pipe 9 is closed, so that the intermediate cooler 7 functions as a cooler.
- the low-pressure refrigerant (see point A in FIGS. 7 to 9) is sucked into the compression mechanism 2 from the suction pipe 2a, and first, until the intermediate pressure is reached by the compression element 2c. After being compressed, it is discharged into the intermediate refrigerant pipe 8 (see point B1 in FIGS. 7 to 9).
- the intermediate pressure refrigerant discharged from the preceding compression element 2c is cooled by exchanging heat with air or water as a cooling source in the intermediate cooler 7 (see point C1 in FIGS. 7 to 9). .
- the refrigerant cooled in the intermediate cooler 7 is further cooled by joining 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. 8) by the two-stage compression operation by the compression elements 2c and 2d. Has been. Then, the high-pressure refrigerant discharged from the compression mechanism 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant cooler via the switching mechanism 3, and air, water, and heat as the cooling source. It is exchanged and cooled (see point E in FIGS. 7 to 9).
- 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 second second-stage injection pipe 19. . Then, the refrigerant flowing through the second second-stage injection pipe 19 is reduced to the vicinity of the intermediate pressure at the second second-stage injection valve 19a, and then sent to the economizer heat exchanger 20 (see point J in FIGS. 7 to 9).
- the refrigerant flowing through the receiver inlet pipe 18a after being branched to the second second-stage injection pipe 19 flows into the economizer heat exchanger 20 and is cooled by exchanging heat with the refrigerant flowing through the second second-stage injection pipe 19.
- the refrigerant flowing through the second second-stage injection pipe 19 is heated by exchanging heat with the refrigerant flowing through the receiver inlet pipe 18a (see point K in FIGS. 7 to 9), and as described above, the intermediate cooler 7 In this case, the refrigerant merges with the cooled refrigerant. Then, 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 temporarily stored in the receiver 18 (see point I in FIGS. 7 to 9).
- the refrigerant stored in the receiver 18 is sent to the receiver outlet pipe 18b, and is sent to the usage-side expansion mechanism 5c through the receiver outlet pipe 18b and the outlet check valve 17c of the bridge circuit 17 to be used.
- the pressure is reduced by 5c to become a low-pressure gas-liquid two-phase refrigerant (see point F in FIGS. 7 to 9).
- the low-pressure gas-liquid two-phase refrigerant sent to the use-side heat exchanger 6 is heated by exchanging heat with air or water as a heating source to evaporate (FIGS. 7 to 9). Point A).
- 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 switching mechanism 3 is in a heating operation state indicated by a broken line in FIG.
- the opening degree of the third expansion mechanism 5d as the heat source side expansion mechanism and the use side expansion mechanism 5c as the use side expansion valve are adjusted. Further, the expansion mechanism bypass valve 5e is fully opened so that pressure reduction by the first expansion mechanism 5a is not performed. Then, 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 a gas-liquid separator through the first second-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.
- the first second-stage injection on / off valve 18d is opened, and the second second-stage injection valve 19a is fully closed. Further, the cooler on / off valve 12 is closed, and the intermediate cooler bypass on / off valve 11 of the intermediate cooler bypass pipe 9 is opened, so that the intermediate cooler 7 does not function as a cooler.
- the low-pressure refrigerant (refer to the point A in FIGS. 7, 10, and 11) is sucked into the compression mechanism 2 from the suction pipe 2a, and is firstly intermediated by the compression element 2c. After being compressed to the pressure, it is discharged to the intermediate refrigerant pipe 8 (see point B1 in FIGS. 7, 10 and 11). Unlike the cooling operation, the intermediate-pressure refrigerant discharged from the preceding-stage compression element 2c passes through the intermediate cooler bypass pipe 9 without passing through the intermediate cooler 7 (that is, without being cooled). By passing (see point C1 in FIG. 7) and joining 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. 10) by the two-stage compression operation by the compression elements 2c and 2d as in the cooling operation. ) Compressed to a pressure exceeding Then, the high-pressure refrigerant discharged from the compression mechanism 2 is sent via the switching mechanism 3 to the use side heat exchanger 6 that functions as a refrigerant cooler, and air, water, and heat as a cooling source. It is exchanged and cooled (see point F in FIGS. 7, 10 and 11).
- the high-pressure refrigerant cooled in the use-side heat exchanger 6 is reduced to near the intermediate pressure by the use-side expansion mechanism 5c, flows into the receiver inlet pipe 18a through the inlet check valve 17b of the bridge circuit 17, and is expanded.
- the gas passes through the mechanism bypass valve 5e and is temporarily stored in the receiver 18, and gas-liquid separation is performed (see points I, L, and M in FIGS. 7, 10, and 11).
- 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 first 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 sent to the bridge circuit 17 through the receiver outlet pipe 18b, and is reduced in pressure by the third expansion mechanism 5d to become a low-pressure gas-liquid two-phase refrigerant.
- the heat source side heat exchanger 4 that functions as (see point E in FIGS. 7, 10, and 11).
- the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 is heated by exchanging heat with air or water as a heating source to evaporate (FIGS. 7 and 10). , 11 point A).
- the low-pressure refrigerant heated in the heat source side heat exchanger 4 is again sucked into the compression mechanism 2 via the switching mechanism 3. In this way, the heating operation is performed.
- the intermediate injection using the receiver 18 and the first second-stage injection pipe 19 can keep the temperature of the refrigerant sucked into the second-stage compression element 2d low, so that the compression mechanism The temperature of the refrigerant discharged from 2 can be kept low (see points D and D ′ in FIG. 11). Thereby, the power consumption of the compression mechanism 2 can be reduced and the operating efficiency can be improved.
- the intermediate cooler 7 is not allowed to function as a cooler, and compared to the case where the intermediate cooler 7 is functioned as a cooler in the same manner as the cooling operation, the external cooler 7 is externally operated.
- the degree of superheat of the refrigerant sucked into the second-stage compression element 2d is controlled by the opening / closing operation of the first second-stage injection on / off valve 18d.
- the first second-stage injection is performed so that the superheat degree of the refrigerant sucked into the second-stage compression element 2d after the intermediate pressure injection by the receiver 18 is not smaller than a predetermined value.
- the opening / closing operation of the opening / closing valve 18d is performed.
- the degree of superheat of the refrigerant sucked into the compression element 2d at the rear stage is calculated by converting the intermediate pressure of the compression mechanism detected by the intermediate pressure sensor 54 into the saturation temperature, and the temperature of the refrigerant detected by the intermediate temperature sensor 56.
- the refrigerant is obtained by subtracting the saturation temperature of the refrigerant corresponding to the intermediate pressure of the compression mechanism.
- the predetermined value of the superheat degree in this control is, for example, from several degrees Celsius to several tens of degrees Celsius to prevent the intermediate pressure refrigerant sucked into the compression element 2d on the rear stage side from becoming wet. A value larger than at least 0 degree is set.
- the opening / closing operation of the first second-stage injection on / off valve 18d is performed by changing the time ratio between the time t1 for opening the first second-stage injection on / off valve 18d and the time t2 for closing the first second-stage injection on / off valve 18d.
- the intermediate pressure injection by the receiver 18 is actively performed, so that the time t2 relative to the time t1 is increased.
- the receiver In order to reduce the flow rate of the refrigerant returned from 18 to the downstream compression element 2d, the direction in which the time ratio of the time t2 to the time t1 is increased (that is, the time for the first second-stage injection on / off valve 18d to be closed) is increased. To make it longer).
- the degree of superheat of the refrigerant discharged from the front-stage compression element 2c and sucked into the rear-stage compression element 2d is controlled by the opening / closing operation of the first second-stage injection on / off valve 18d. Therefore, even if the liquid refrigerant is mixed with the refrigerant returned to the compression element 2d on the rear stage side from the receiver 18 under the operating condition that a large amount of liquid refrigerant is accumulated in the receiver 18 as the gas-liquid separator, the receiver 18 By reducing the flow rate of the refrigerant returned to the rear-stage compression element 2d, it is possible to prevent the refrigerant sucked into the rear-stage compression element 2d from becoming wet.
- the reliability of the compression mechanism 2 at the time of heating operation is improving.
- intermediate pressure injection is performed by the economizer heat exchanger 20, and the degree of superheat of the refrigerant returned from the second rear-stage injection pipe 19 to the rear-stage compression element 2d is:
- the target value is controlled by adjusting the opening of the second second-stage injection valve 19a.
- the temperature of the air as the heat source of the intermediate cooler 7 is saturated with the intermediate-pressure refrigerant sent from the front-stage compression element 2c to the rear-stage compression element 2d.
- the intercooler bypass pipe 9 is used to prevent the refrigerant from flowing into the intercooler 7, so that the temperature of the air as the heat source of the intercooler 7 is reduced. Even when the operating condition is low, it is possible to prevent the refrigerant sucked into the compression element 2d on the rear stage from getting wet, and thus the reliability of the compression mechanism 2 is improved.
- the refrigerant sucked into the downstream compression element 2d is wet due to the cooling operation by the intermediate cooler 7 and the influence of the refrigerant returned to the downstream compression element 2d by the intermediate pressure injection. Therefore, the reliability of the compression mechanism 2 is improved in both the cooling operation and the heating operation.
- the first expansion mechanism 5a and the receiver 18 are exchanged with the heat source side heat exchanger 4 and the use side heat exchange via the bridge circuit 17 (including the third expansion mechanism 5d).
- the bridge circuit 17 is omitted and the first expansion mechanism 5 a is connected between the heat source side heat exchanger 4 and the receiver 18.
- the refrigerant flowing between the heat source side heat exchanger 4 and the use side heat exchanger 6 is used as the use side expansion mechanism 5c, the receiver 18, and the first expansion.
- Refrigerant circuit 7 configured to flow in the order of mechanism 5a It may be set to 0.
- the bridge circuit 17 is omitted, and when the switching mechanism 3 is in the heating operation state, it flows between the heat source side heat exchanger 4 and the use side heat exchanger 6.
- the point that the refrigerant flows in the order of the use side expansion mechanism 5c, the receiver 18, and the first expansion mechanism 5a is different (therefore, the points I and L in FIGS. 10 and 11 are interchanged), but the same as described above. An effect can be obtained.
- the configuration in the above-described embodiment is adopted as the configuration of the intercooler 7 and the like.
- the configuration of 3 may be adopted.
- (7) Modification 5 In the above-described embodiment and its modification, the refrigerant discharged from the front-stage compression element of the two compression elements 2c and 2d by the single uniaxial two-stage compression structure 21 is used as the rear-stage compression element.
- the two-stage compression type compression mechanism 2 that compresses sequentially in the above-described manner is configured.
- a multistage compression mechanism may be employed rather than a two-stage compression type such as a three-stage compression type, or a single-stage compression type may be adopted.
- 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 610 (see FIG. 7) that does not have the bridge circuit 17 in the above-described modified example 4, instead of the two-stage compression type compression mechanism 2, two-stage compression type compression is performed.
- a refrigerant circuit 810 employing a compression mechanism 102 in which the mechanisms 103 and 104 are connected in parallel may be used.
- 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.
- 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.
- 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 cooler 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 mechanism
- This is a heat exchanger that cools the refrigerant combined with the refrigerant discharged from the compression element 104c on the upstream side of 104. That is, the intermediate cooler 7 functions as a cooler common to the two compression mechanisms 103 and 104. Therefore, the circuit configuration around the compression mechanism 102 when the intermediate cooler 7 is provided for the parallel multi-stage compression type compression mechanism 102 in which the multi-stage compression type compression mechanisms 103 and 104 are connected in parallel in a plurality of systems is simplified. It has been.
- 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.
- water or brine is used as a heating source or a cooling source for performing heat exchange with the refrigerant flowing in the use-side heat exchanger 6, and heat exchange is performed in the use-side heat exchanger 6.
- the present invention may be applied to a so-called chiller type air conditioner provided with a secondary heat exchanger for exchanging heat between the water or brine and indoor air.
- 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.
- the refrigerant operating in the supercritical region is not limited to carbon dioxide, and ethylene, ethane, nitrogen oxide, or the like may be used.
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Abstract
Description
この問題に対して、前段側の圧縮要素から吐出されて後段側の圧縮要素に吸入される冷媒の冷却器として機能する中間冷却器を前段側の圧縮要素から吐出された冷媒を後段側の圧縮要素に吸入させるための中間冷媒管に設けることで、後段側の圧縮要素に吸入される冷媒の温度を低くし、その結果、後段側の圧縮要素から吐出される冷媒の温度を低くして、室外熱交換器における放熱ロスを小さくすることが考えられる。
そこで、この冷凍装置では、中間冷却器の熱源温度又は中間冷却器の出口冷媒温度が前段側の圧縮要素から後段側の圧縮要素に送られる冷媒の飽和温度以下になった際に、中間冷却器バイパス管を用いて、中間冷却器に冷媒が流れないようにする湿り防止制御を行っている。
これにより、この冷凍装置では、中間冷却器の熱源温度が低い運転条件になった場合であっても、後段側の圧縮要素に吸入される冷媒が湿り状態になるのを防ぐことができる。
この冷凍装置では、中間冷却器の熱源である空気の温度が低い運転条件になった場合であっても、後段側の圧縮要素に吸入される冷媒が湿り状態になるのを防ぐことができる。
この冷凍装置では、中間冷却器の熱源である水の温度が低い運転条件になった場合であっても、後段側の圧縮要素に吸入される冷媒が湿り状態になるのを防ぐことができる。しかも、この冷凍装置では、湿り防止制御において、中間冷却器への水の供給を止めるようにしているため、中間冷却器内の冷媒が液状態になって溜まり込むのを防ぐことができる。
この問題に対して、前段側の圧縮要素から吐出されて後段側の圧縮要素に吸入される冷媒の冷却器として機能する中間冷却器を前段側の圧縮要素から吐出された冷媒を後段側の圧縮要素に吸入させるための中間冷媒管に設けることで、後段側の圧縮要素に吸入される冷媒の温度を低くし、その結果、後段側の圧縮要素から吐出される冷媒の温度を低くして、室外熱交換器における放熱ロスを小さくすることが考えられる。
そこで、この冷凍装置では、中間冷却器の熱源温度又は中間冷却器の出口冷媒温度が前段側の圧縮要素から後段側の圧縮要素に送られる冷媒の飽和温度以下になった際に、中間冷却器を流れる水の流量を減少させる湿り防止制御を行っている。
これにより、この冷凍装置では、中間冷却器の熱源である水の温度が低い運転条件になった場合であっても、後段側の圧縮要素に吸入される冷媒が湿り状態になるのを防ぐことができる。
この冷凍装置では、湿り防止制御において、さらに、中間冷却器の出口冷媒温度が前段側の圧縮要素から後段側の圧縮要素に送られる冷媒の飽和温度よりも高くなるように、中間冷却器を流れる水の流量を制御しているため、後段側の圧縮要素に吸入される冷媒が湿り状態になるのを防ぐことができるだけでなく、後段側の圧縮要素に吸入される冷媒の温度を極力低くして、これにより、後段側の圧縮要素から吐出される冷媒の温度を低く抑えるとともに、圧縮機構の消費動力を減らすことができる。
この冷凍装置では、中間冷却器による後段側の圧縮要素に吸入される冷媒の冷却に加えて、後段側インジェクション管を用いた中間インジェクションによって、後段側の圧縮要素に吸入される冷媒の温度をさらに低く抑えることができるため、圧縮機構から吐出される冷媒の温度をさらに低く抑えることができ、圧縮機構の消費動力を減らすことができる。
2、102 圧縮機構
4 熱源側熱交換器
6 利用側熱交換器
7 中間冷却器
8 中間冷媒管
9 中間冷却器バイパス管
18c 第1後段側インジェクション管
19 第2後段側インジェクション管
(1)空気調和装置の構成
図1は、本発明にかかる冷凍装置の一実施形態としての空気調和装置1の概略構成図である。空気調和装置1は、冷房運転が可能となるように構成された冷媒回路10を有し、超臨界域で作動する冷媒(ここでは、二酸化炭素)を使用して二段圧縮式冷凍サイクルを行う装置である。
空気調和装置1の冷媒回路10は、主として、圧縮機構2と、熱源側熱交換器4と、膨張機構5と、利用側熱交換器6と、中間冷却器7とを有している。
圧縮機構2は、本実施形態において、2つの圧縮要素で冷媒を二段圧縮する圧縮機21から構成されている。圧縮機21は、ケーシング21a内に、圧縮機駆動モータ21bと、駆動軸21cと、圧縮要素2c、2dとが収容された密閉式構造となっている。圧縮機駆動モータ21bは、駆動軸21cに連結されている。そして、この駆動軸21cは、2つの圧縮要素2c、2dに連結されている。すなわち、圧縮機21は、2つの圧縮要素2c、2dが単一の駆動軸21cに連結されており、2つの圧縮要素2c、2dがともに圧縮機駆動モータ21bによって回転駆動される、いわゆる一軸二段圧縮構造となっている。圧縮要素2c、2dは、本実施形態において、ロータリ式やスクロール式等の容積式の圧縮要素である。そして、圧縮機21は、吸入管2aから冷媒を吸入し、この吸入された冷媒を圧縮要素2cによって圧縮した後に中間冷媒管8に吐出し、中間冷媒管8に吐出された冷媒を圧縮要素2dに吸入させて冷媒をさらに圧縮した後に吐出管2bに吐出するように構成されている。ここで、中間冷媒管8は、圧縮要素2dの前段側に接続された圧縮要素2cから吐出された冷媒を、圧縮要素2cの後段側に接続された圧縮要素2dに吸入させるための冷媒管である。また、吐出管2bは、圧縮機構2から吐出された冷媒を熱源側熱交換器4に送るための冷媒管であり、吐出管2bには、油分離機構41と逆止機構42とが設けられている。油分離機構41は、圧縮機構2から吐出される冷媒に同伴する冷凍機油を冷媒から分離して圧縮機構2の吸入側へ戻す機構であり、主として、圧縮機構2から吐出される冷媒に同伴する冷凍機油を冷媒から分離する油分離器41aと、油分離器41aに接続されており冷媒から分離された冷凍機油を圧縮機構2の吸入管2aに戻す油戻し管41bとを有している。油戻し管41bには、油戻し管41bを流れる冷凍機油を減圧する減圧機構41cが設けられている。減圧機構41cは、本実施形態において、キャピラリチューブが使用されている。逆止機構42は、圧縮機構2の吐出側から熱源側熱交換器4への冷媒の流れを許容し、かつ、熱源側熱交換器4から圧縮機構2の吐出側への冷媒の流れを遮断するための機構であり、本実施形態において、逆止弁が使用されている。
熱源側熱交換器4は、冷媒の冷却器として機能する熱交換器である。熱源側熱交換器4は、その一端が圧縮機構2に接続されており、その他端が膨張機構5に接続されている。熱源側熱交換器4は、空気を熱源(すなわち、冷却源)とする熱交換器である。そして、熱源としての空気は、図示しない熱源側ファンによって熱源側熱交換器4に供給されるようになっている。
膨張機構5は、冷媒を減圧する機構であり、本実施形態において、電動膨張弁が使用されている。膨張機構5は、その一端が熱源側熱交換器4に接続され、その他端が利用側熱交換器6に接続されている。また、本実施形態において、膨張機構5は、熱源側熱交換器4において冷却された高圧の冷媒を利用側熱交換器6に送る前に減圧する。
中間冷却器7は、中間冷媒管8に設けられており、前段側の圧縮要素2cから吐出されて圧縮要素2dに吸入される冷媒の冷却器として機能する熱交換器である。中間冷却器7は、空気を熱源(すなわち、冷却源)とする熱交換器である。そして、熱源としての空気は、図示しない熱源側ファンによって中間冷却器7に供給されるようになっている。尚、中間冷却器7は、熱源側熱交換器4と一体化される場合があり、この場合には、熱源側熱交換器4及び中間冷却器7の両方に共通の熱源側ファンによって、熱源としての空気を供給する場合もある。このように、中間冷却器7は、冷媒回路10を循環する冷媒を用いたものではないという意味で、外部熱源を用いた冷却器ということができる。
また、中間冷媒管8には、中間冷却器バイパス管9との接続部から中間冷却器7側の位置(すなわち、中間冷却器7の入口側の中間冷却器バイパス管9との接続部から中間冷却器7の出口側の接続部までの部分)に、冷却器開閉弁12が設けられている。この冷却器開閉弁12は、中間冷却器7を流れる冷媒の流量を制限する機構である。冷却器開閉弁12は、本実施形態において、電磁弁である。この冷却器開閉弁12は、本実施形態において、後述の湿り防止制御のような一時的な運転を行う場合を除いて、基本的には開けられる。尚、冷却器開閉弁12は、本実施形態において、中間冷却器7の入口側の位置に設けられている。
さらに、空気調和装置1には、各種のセンサが設けられている。具体的には、中間冷却器7の出口には、中間冷却器7の出口における冷媒の温度を検出する中間冷却器出口温度センサ52が設けられている。空気調和装置1には、中間冷却器7の熱源としての空気の温度を検出する空気温度センサ53が設けられている。中間冷媒管8には、中間冷媒管8を流れる冷媒の圧力である圧縮機構中間圧力を検出する中間圧力センサ54が設けられている。また、空気調和装置1は、ここでは図示しないが、圧縮機構2、膨張機構5、中間冷却器バイパス開閉弁11、冷却器開閉弁12等の空気調和装置1を構成する各部の動作を制御する制御部を有している。
次に、本実施形態の空気調和装置1の動作について、図1~図3を用いて説明する。ここで、図2は、冷房運転時の冷凍サイクルが図示された圧力-エンタルピ線図であり、図3は、冷房運転時の冷凍サイクルが図示された温度-エントロピ線図である。尚、以下の冷房運転における運転制御、及び、中間冷却器7における冷却により後段側の圧縮要素に吸入される冷媒が湿り状態になるのを防ぐ湿り防止制御は、上述の制御部(図示せず)によって行われる。また、以下の説明において、「高圧」とは、冷凍サイクルにおける高圧(すなわち、図2、3の点D、D’、Eにおける圧力)を意味し、「低圧」とは、冷凍サイクルにおける低圧(すなわち、図2、3の点A、Fにおける圧力)を意味し、「中間圧」や「圧縮機構中間圧力」とは、冷凍サイクルにおける中間圧力(すなわち、図2、3の点B1、C1における圧力)を意味している。
この冷媒回路10の状態において、圧縮機構2を駆動すると、低圧の冷媒(図1~図3の点A参照)は、吸入管2aから圧縮機構2に吸入され、まず、圧縮要素2cによって中間圧力まで圧縮された後に、中間冷媒管8に吐出される(図1~図3の点B1参照)。この前段側の圧縮要素2cから吐出された中間圧の冷媒は、中間冷却器7において、冷却源としての空気と熱交換を行うことで冷却される(図1~図3の点C1参照)。この中間冷却器7において冷却された冷媒は、次に、圧縮要素2cの後段側に接続された圧縮要素2dに吸入されてさらに圧縮されて、圧縮機構2から吐出管2bに吐出される(図1~図3の点D参照)。ここで、圧縮機構2から吐出された高圧の冷媒は、圧縮要素2c、2dによる二段圧縮動作によって、臨界圧力(すなわち、図2に示される臨界点CPにおける臨界圧力Pcp)を超える圧力まで圧縮されている。そして、この圧縮機構2から吐出された高圧の冷媒は、油分離機構41を構成する油分離器41aに流入し、同伴する冷凍機油が分離される。また、油分離器41aにおいて高圧の冷媒から分離された冷凍機油は、油分離機構41を構成する油戻し管41bに流入し、油戻し管41bに設けられた減圧機構41cで減圧された後に圧縮機構2の吸入管2aに戻されて、再び、圧縮機構2に吸入される。次に、油分離機構41において冷凍機油が分離された後の高圧の冷媒は、逆止機構42を通じて、冷媒の冷却器として機能する熱源側熱交換器4に送られる。そして、熱源側熱交換器4に送られた高圧の冷媒は、熱源側熱交換器4において、冷却源としての水又は空気と熱交換を行って冷却される(図1~図3の点E参照)。そして、熱源側熱交換器4において冷却された高圧の冷媒は、膨張機構5によって減圧されて低圧の気液二相状態の冷媒となり、冷媒の加熱器として機能する利用側熱交換器6に送られる(図1~図3の点F参照)。そして、利用側熱交換器6に送られた低圧の気液二相状態の冷媒は、利用側熱交換器6において、加熱源としての水又は空気と熱交換を行って加熱されて、蒸発することになる(図1~図3の点A参照)。そして、この利用側熱交換器6において加熱された低圧の冷媒は、再び、圧縮機構2に吸入される。このようにして、冷房運転が行われる。
上述のような中間冷却器7による中間圧の冷媒の冷却を伴う冷房運転においては、中間冷却器7の熱源としての空気が低い運転条件になると、前段側の圧縮要素2cから吐出されて後段側の圧縮要素2dに吸入される冷媒が過度に冷却されてしまうおそれがあり、これにより、後段側の圧縮要素2dに吸入される冷媒が湿り状態になってしまい、圧縮機構2の信頼性が損なわれてしまうおそれがある。
そこで、本実施形態では、中間冷却器7の熱源温度が、前段側の圧縮要素2cから後段側の圧縮要素2dに送られる冷媒の飽和温度以下になった際に、中間冷却器バイパス管9を用いて、中間冷却器7に冷媒が流れないようにする湿り防止制御を行うようにしている。具体的には、本実施形態において、空気温度センサ53により検出される中間冷却器7の熱源としての空気の温度が、中間圧力センサ54により検出される圧縮機構中間圧力を換算して得られる飽和温度以下になっている場合には、中間冷却器バイパス管9の中間冷却器バイパス開閉弁11を開けるとともに冷却器開閉弁12を閉めることによって、前段側の圧縮要素2cから吐出された冷媒を、中間冷却器バイパス管9を通じて後段側の圧縮要素2dの吸入側に流し、これによって、中間冷却器7に中間圧の冷媒が流れないようにしている。尚、本実施形態のような超臨界域で作動する冷媒を使用している場合には、前段側の圧縮要素2cから吐出された冷媒の圧力が高くなり、圧縮機構中間圧力が臨界圧力(すなわち、図2に示される臨界点CPにおける臨界圧力Pcp)を超える運転条件になる場合もあり得るが、このような運転条件においては、高圧の冷媒だけでなく中間圧の冷媒においても、飽和状態という概念が存在しなくなることから、上述の湿り防止制御を行う必要がなくなる。このため、この湿り防止制御では、熱源としての空気の温度が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる冷媒の飽和温度以下になっているかどうかの判断を行う前に、圧縮機構中間圧力が臨界圧力よりも低いかどうかを判断して、圧縮機構中間圧力が臨界圧力以上である場合には、中間冷却器7に冷媒を流したままにして後段側の圧縮要素2dに吸入される冷媒の温度をできる限り低くするようにし、圧縮機構中間圧力が臨界圧力よりも低い場合には、上述のように、空気温度センサ53により検出される中間冷却器7の熱源としての空気の温度が、中間圧力センサ54により検出される圧縮機構中間圧力を換算して得られる飽和温度以下になっているかどうかを判断して、中間冷却器7の熱源としての空気の温度が、圧縮機構中間圧力を換算して得られる飽和温度以下になっている場合には、中間冷却器7に中間圧の冷媒が流れないようにし、中間冷却器7の熱源としての空気の温度が、圧縮機構中間圧力を換算して得られる飽和温度よりも高い場合には、中間冷却器7に冷媒を流したままにするようにしている。
また、この空気調和装置1では、中間冷却器7の熱源としての空気の温度が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる中間圧の冷媒の飽和温度以下になった際に、中間冷却器7の入口側に設けられた冷却器開閉弁12を閉めるようにしているため、前段側の圧縮要素2cから吐出された冷媒をすべて中間冷却器バイパス管9に流すことができるとともに、中間冷媒管8や中間冷媒管バイパス管9を流れる中間圧の冷媒が中間冷却器7の入口側から中間冷却器7に流入して中間冷却器7内に溜まり込むのを防ぐことができる。しかも、本実施形態において、中間冷却器7の出口側には、逆止機構15が設けられているため、中間冷媒管8や中間冷媒管バイパス管9を流れる中間圧の冷媒が中間冷却器7の出口側から中間冷却器7に流入して中間冷却器7内に溜まり込むのを防ぐことができる。特に、中間冷却器7が熱源側熱交換器4と一体化されるとともに、熱源側熱交換器4及び中間冷却器7の両方に共通の熱源側ファン(図示せず)によって熱源側熱交換器4及び中間冷却器7の両方に熱源としての空気が供給される構成においては、熱源側熱交換器4に熱源としての空気が供給される限り、中間冷却器7にも熱源としての空気が供給され続けることになり、これによって、中間圧の冷媒が中間冷却器7に流入して中間冷却器7内に溜まり込むおそれがあることから、冷却器開閉弁12及び逆止機構15を設けることが有効である。
(3)変形例1
上述の実施形態においては、中間冷却器7として、空気を熱源とする熱交換器を使用しているが、中間冷却器7として、水を熱源とする熱交換器を使用してもよい。
例えば、図4に示されるように、中間冷却用水配管14を通じて中間冷却器7に水を供給するように構成し、中間冷却器7の熱源としての水の温度(ここでは、中間冷却器7の水入口側に設けられた水温センサ58により検出される中間冷却器7に供給される水の温度)が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる中間圧の冷媒の飽和温度以下であるかどうか、又は、中間冷却器7の出口における冷媒の温度(ここでは、中間冷却器出口温度センサ52により検出される冷媒の温度)が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる中間圧の冷媒の飽和温度以下であるかどうかを判断し、中間冷却器7の熱源としての水の温度又は中間冷却器7の出口における冷媒の温度が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる冷媒の飽和温度以下になっていると判断された場合には、上述の実施形態と同様、中間冷却器バイパス管9の中間冷却器バイパス開閉弁11を開けるとともに冷却器開閉弁12を閉めることによって、前段側の圧縮要素2cから吐出された冷媒を、中間冷却器バイパス管9を通じて後段側の圧縮要素2dの吸入側に流し、これによって、中間冷却器7に中間圧の冷媒が流れないようにする湿り防止制御を行うようにしてもよい。
また、図5に示されるように、中間冷却用水配管14に水開閉弁14aを設けるように構成し、上述の中間冷却器バイパス管9を用いて中間冷却器7に中間圧の冷媒が流れないようにする制御を行うとともに、水開閉弁14aを閉めることによって中間冷却器7への水の供給を止める制御を行うようにしてもよい。ここで、水開閉弁14aは、開閉制御が可能な電磁弁である。
この場合には、さらに、中間冷却器7内の冷媒が液状態になって溜まり込むのを防ぐことができる。
(4)変形例2
上述の変形例1においては、中間冷却用水配管14を通じて中間冷却器7に水を供給するように構成するとともに、中間冷却用水配管14に水開閉弁14aを設けるように構成し、中間冷却器7の熱源としての水の温度又は中間冷却器7の出口における冷媒の温度が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる冷媒の飽和温度以下になっていると判断された場合に、中間冷却器バイパス管9を用いて中間冷却器7に中間圧の冷媒が流れないようにする制御を行うとともに、水開閉弁14aを閉めることによって中間冷却器7への水の供給を止める制御を行う湿り防止制御を採用しているが(図5参照)、中間冷却器バイパス開閉弁11を含む中間冷却器バイパス管9や冷却器開閉弁12のような中間冷却器7に中間圧の冷媒が流れないようにする制御を行うための構成を省略して、中間冷却器7への水の供給を止める制御だけを行う湿り防止制御を採用してもよい。
(5)変形例3
上述の変形例2の構成(図6参照)において、水開閉弁14aを開度調節が可能な弁によって構成し、中間冷却器7の出口における冷媒の温度が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる冷媒の飽和温度以下になっていると判断された場合には、水開閉弁14aの開度を小さくすることで中間冷却器7へ供給される水の流量を減少させて、後段側の圧縮要素2dに吸入される冷媒が湿り状態になるのを防ぎ、さらに、中間冷却器7の出口における冷媒の温度が前段側の圧縮要素2cから後段側の圧縮要素2dに送られる冷媒の飽和温度よりも高くなるように、中間冷却器7を流れる水の流量を制御する湿り防止制御を採用してもよい。
(6)変形例4
上述の実施形態及びその変形例における冷媒回路10(図1、4、5、6参照)においては、1つの利用側熱交換器6を有し、かつ、冷房運転が可能な構成となっているが、複数の空調空間の空調負荷に応じた冷房や暖房を行うこと等を目的として、冷房運転と暖房運転とを切り換えるための切換機構3と、互いに並列に接続された複数の利用側熱交換器6と、熱源側熱交換器4と利用側熱交換器6との間を流れる冷媒を一時的に溜めるレシーバ18とを有する構成にするとともに、各利用側熱交換器6を流れる冷媒の流量を制御して各利用側熱交換器6において必要とされる冷凍負荷を得ることができるようにするために、気液分離器としてのレシーバ18と利用側熱交換器6との間において各利用側熱交換器6に対応するように利用側膨張機構5cを設ける場合(例えば、後述の図7、12において、後段側インジェクション管18c、19及びエコノマイザ熱交換器20を有しない構成)がある。そして、このような構成において、気液分離器としてのレシーバ18から後段側の圧縮要素2dに冷媒を戻すことによって、圧縮機構2の前段側の圧縮要素2cから吐出されて後段側の圧縮要素2dに吸入される圧縮機構中間圧力の冷媒と合流させる中間圧インジェクションを行い、後段側の圧縮要素2dから吐出される冷媒の温度を低下させるとともに、圧縮機構2の消費動力を減らし、運転効率の向上を図ることが考えられる。
ところが、冷房運転のように、熱源側熱交換器4において冷却された後に気液分離器としてのレシーバ18に流入するまでの間に、熱源側膨張機構としての第1膨張機構5a(例えば、後述の図7、12の第1膨張機構5aを参照)以外に大幅な減圧操作が行われることがなく、冷凍サイクルにおける高圧から冷凍サイクルの中間圧付近までの圧力差を利用できる条件においては、熱源側熱交換器4と第1膨張機構5aとの間を流れる冷媒を分岐して後段側の圧縮要素2dに戻す第2後段側インジェクション管19と、熱源側熱交換器4と第1膨張機構5aとの間を流れる冷媒と第2後段側インジェクション管19を流れる冷媒との熱交換を行うエコノマイザ熱交換器20とを設けて、このエコノマイザ熱交換器20における熱交換によって加熱された後の第2後段側インジェクション管19を流れる冷媒を後段側の圧縮要素2dに戻す(すなわち、エコノマイザ熱交換器20による中間圧インジェクションを行う)ことが好ましい(例えば、後述の図7、12の第2後段側インジェクション管19及びエコノマイザ熱交換器20を参照)。なぜなら、エコノマイザ熱交換器20による中間圧インジェクションは、エコノマイザ熱交換器20における熱交換量の大小によって後段側の圧縮要素2dに戻すことができる冷媒の流量が変動することから、暖房運転のように、エコノマイザ熱交換器20の入口における冷媒の圧力と圧縮機構中間圧力との圧力差が小さい場合には、エコノマイザ熱交換器20における熱交換量が小さくなって後段側の圧縮要素2dに戻すことができる冷媒の流量が小さくなり、その適用が困難であるが、エコノマイザ熱交換器20の入口における冷媒の圧力と圧縮機構中間圧力との圧力差が大きい場合には、エコノマイザ熱交換器20における熱交換量が大きくなって後段側の圧縮要素2dに戻すことができる冷媒の流量が大きくなり、その適用が有効である。特に、二酸化炭素のような超臨界域で作動する冷媒を使用する場合には、冷凍サイクルにおける高圧が臨界圧力を超える圧力になることから、冷凍サイクルにおける高圧と中間圧との圧力差がさらに大きくなるため、エコノマイザ熱交換器20による中間圧インジェクションが有利である。しかも、二酸化炭素のような超臨界域で作動する冷媒を使用する場合には、気液分離器圧力が臨界圧力よりも高い圧力まで上昇して、気液分離器としてのレシーバ18内の冷媒をガス冷媒と液冷媒に分離することが困難な状況になるおそれもあるため、この点も考慮すると、冷房運転のように、冷凍サイクルにおける高圧から冷凍サイクルの中間圧付近までの圧力差を利用できる条件においては、エコノマイザ熱交換器20による中間圧インジェクションを使用することが好ましい。
切換機構3は、冷媒回路610内における冷媒の流れの方向を切り換えるための機構であり、冷房運転時には、熱源側熱交換器4を圧縮機構2によって圧縮される冷媒の冷却器として、かつ、利用側熱交換器6を熱源側熱交換器4において冷却された冷媒の加熱器として機能させるために、圧縮機構2の吐出側と熱源側熱交換器4の一端とを接続するとともに圧縮機21の吸入側と利用側熱交換器6とを接続し(図7の切換機構3の実線を参照、以下、この切換機構3の状態を「冷却運転状態」とする)、暖房運転時には、利用側熱交換器6を圧縮機構2によって圧縮される冷媒の冷却器として、かつ、熱源側熱交換器4を利用側熱交換器6において冷却された冷媒の加熱器として機能させるために、圧縮機構2の吐出側と利用側熱交換器6とを接続するとともに圧縮機構2の吸入側と熱源側熱交換器4の一端とを接続することが可能である(図7の切換機構3の破線を参照、以下、この切換機構3の状態を「加熱運転状態」とする)。本変形例において、切換機構3は、圧縮機構2の吸入側、圧縮機構2の吐出側、熱源側熱交換器4及び利用側熱交換器6に接続された四路切換弁である。尚、切換機構3は、四路切換弁に限定されるものではなく、例えば、複数の電磁弁を組み合わせる等によって、上述と同様の冷媒の流れの方向を切り換える機能を有するように構成したものであってもよい。
ブリッジ回路17は、熱源側熱交換器4と利用側熱交換器6との間に設けられており、レシーバ18の入口に接続されるレシーバ入口管18a、及び、レシーバ18の出口に接続されるレシーバ出口管18bに接続されている。ブリッジ回路17は、本変形例において、3つの逆止弁17a、17b、17cと、熱源側膨張機構としての第3膨張機構5dとを有している。そして、入口逆止弁17aは、熱源側熱交換器4からレシーバ入口管18aへの冷媒の流通のみを許容する逆止弁である。入口逆止弁17bは、利用側熱交換器6からレシーバ入口管18aへの冷媒の流通のみを許容する逆止弁である。すなわち、入口逆止弁17a、17bは、熱源側熱交換器4及び利用側熱交換器6の一方からレシーバ入口管18aに冷媒を流通させる機能を有している。出口逆止弁17cは、レシーバ出口管18bから利用側熱交換器6への冷媒の流通のみを許容する逆止弁である。第3膨張機構5dは、冷媒を減圧する機構であり、ブリッジ回路17の一部を構成している。すなわち、出口逆止弁17c及び第3膨張機構5dは、レシーバ出口管18bから熱源側熱交換器4及び利用側熱交換器6の他方に冷媒を流通させる機能を有している。このため、第3膨張機構5dは、切換機構3を冷却運転状態にする冷房運転の際には、全閉状態にされ、切換機構3を加熱運転状態にする暖房運転の際には、レシーバ出口管18bから熱源側熱交換器4に送られる冷媒を減圧するようになっている。尚、第3膨張機構5dは、本変形例において、電動膨張弁である。
レシーバ18は、第1膨張機構5aで減圧された後の冷媒を一時的に溜めることができる容器であり、その入口がレシーバ入口管18aに接続されており、その出口がレシーバ出口管18bに接続されている。また、レシーバ18には、第1後段側インジェクション管18c及び吸入戻し管18fが接続されている。ここで、第1後段側インジェクション管18cと吸入戻し管18fとは、レシーバ18側の部分が一体となっている。
このように、レシーバ18は、第1後段側インジェクション開閉弁18dや吸入戻し開閉弁18gを開けることによって第1後段側インジェクション管18cや吸入戻し管18fを使用する場合には、熱源側熱交換器4と利用側熱交換器6との間を流れる冷媒を、膨張機構5a、5dと利用側膨張機構5cとの間において、気液分離する気液分離器として機能し、主として、レシーバ18において気液分離されたガス冷媒をレシーバ18の上部から圧縮機構2の後段側の圧縮要素2dや前段側の圧縮要素2cに戻すことができるようになっている。
第2後段側インジェクション管19は、熱源側熱交換器4と利用側熱交換器6との間を流れる冷媒を分岐して圧縮機構2の後段側の圧縮要素2dに戻す機能を有している。本変形例において、第2後段側インジェクション管19は、レシーバ入口管18aを流れる冷媒を分岐して後段側の圧縮要素2dの吸入側に戻すように設けられている。より具体的には、第2後段側インジェクション管19は、レシーバ入口管18aの第1膨張機構5aの上流側の位置(すなわち、切換機構3を冷却運転状態にしている際には、熱源側熱交換器4と第1膨張機構5aとの間)から冷媒を分岐して中間冷媒管8の中間冷却器7の下流側の位置に戻すように設けられている。ここで、第1後段側インジェクション管18cと第2後段側インジェクション管19とは、中間冷媒管8側の部分が一体となっている。また、この第2後段側インジェクション管19には、開度制御が可能な第2後段側インジェクション弁19aが設けられている。そして、第2後段側インジェクション弁19aは、本変形例において、電動膨張弁である。
さらに、本変形例において、エコノマイザ熱交換器20の第2後段側インジェクション管19側の出口には、エコノマイザ熱交換器20の第2後段側インジェクション管19側の出口における冷媒の温度を検出するエコノマイザ出口温度センサ55が設けられている。また、レシーバ入口管18aには、第1膨張機構5aよりもレシーバ18側の位置に、レシーバ18における冷媒の温度を検出する気液分離器温度センサ57が設けられている。尚、この気液分離器温度センサ57は、レシーバ出口管18bに設けられていてもよいし、例えば、レシーバ18の底部のように、レシーバ18に直接設けられていてもよい。
次に、本変形例の空気調和装置1の動作について、図7~図11を用いて説明する。ここで、図8は、本変形例における冷房運転時の冷凍サイクルが図示された圧力-エンタルピ線図であり、図9は、本変形例における冷房運転時の冷凍サイクルが図示された温度-エントロピ線図であり、図10は、本変形例における暖房運転時の冷凍サイクルが図示された圧力-エンタルピ線図であり、図11は、本変形例における暖房運転時の冷凍サイクルが図示された温度-エントロピ線図である。尚、以下の冷房運転や暖房運転における運転制御、及び、気液分離器圧力の低下を抑える制御は、上述の制御部(図示せず)によって行われる。また、以下の説明において、「高圧」とは、冷凍サイクルにおける高圧(すなわち、図8、9の点D、D’、E、Hにおける圧力や図10、11の点D、D’、F、Hにおける圧力)を意味し、「低圧」とは、冷凍サイクルにおける低圧(すなわち、図8、9の点A、Fにおける圧力や図10、11の点A、Eにおける圧力)を意味し、「中間圧」とは、冷凍サイクルにおける中間圧(すなわち、図8~11の点B1、C1、Gにおける圧力)を意味している。
冷房運転時は、切換機構3が図7の実線で示される冷却運転状態とされる。熱源側膨張機構としての第1膨張機構5a及び利用側膨張弁としての利用側膨張機構5cは、開度調節される。また、第3膨張機構5d及び膨張機構バイパス弁5eは、全閉状態にされる。そして、切換機構3を冷却運転状態にしている際には、気液分離器としてのレシーバ18による中間圧インジェクションを行わずに、第2後段側インジェクション管19を通じて、エコノマイザ熱交換器20において加熱された冷媒を後段側の圧縮要素2dに戻すエコノマイザ熱交換器20による中間圧インジェクションを行うようにしている。より具体的には、第1後段側インジェクション開閉弁18dは閉状態にされて、第2後段側インジェクション弁19aが開度調節される。ここで、第2後段側インジェクション弁19aは、エコノマイザ熱交換器20の第2後段側インジェクション管19側の出口における冷媒の過熱度が目標値になるように開度調節される、いわゆる過熱度制御がなされるようになっている。本変形例において、エコノマイザ熱交換器20の第2後段側インジェクション管19側の出口における冷媒の過熱度は、中間圧力センサ54により検出される中間圧を飽和温度に換算し、エコノマイザ出口温度センサ55により検出される冷媒温度からこの冷媒の飽和温度値を差し引くことによって得られる。尚、本変形例では採用していないが、エコノマイザ熱交換器20の第2後段側インジェクション管19側の入口に温度センサを設けて、この温度センサにより検出される冷媒温度をエコノマイザ出口温度センサ55により検出される冷媒温度から差し引くことによって、エコノマイザ熱交換器20の第2後段側インジェクション管19側の出口における冷媒の過熱度を得るようにしてもよい。さらに、冷却器開閉弁12が開けられ、また、中間冷却器バイパス管9の中間冷却器バイパス開閉弁11が閉められることによって、中間冷却器7が冷却器として機能する状態とされる。
<暖房運転>
暖房運転時は、切換機構3が図7の破線で示される加熱運転状態とされる。熱源側膨張機構としての第3膨張機構5d及び利用側膨張弁としての利用側膨張機構5cは、開度調節される。また、膨張機構バイパス弁5eは、全開状態にされて、第1膨張機構5aによる減圧が行われないようになっている。そして、切換機構3を加熱運転状態にしている際には、エコノマイザ熱交換器20による中間圧インジェクションを行わずに、第1後段側インジェクション管18cを通じて、気液分離器としてのレシーバ18から冷媒を後段側の圧縮要素2dに戻すレシーバ18による中間圧インジェクションを行うようにしている。より具体的には、第1後段側インジェクション開閉弁18dが開状態にされて、第2後段側インジェクション弁19aが全閉状態にされる。さらに、冷却器開閉弁12が閉められ、また、中間冷却器バイパス管9の中間冷却器バイパス開閉弁11が開けられることによって、中間冷却器7が冷却器として機能しない状態とされる。
<後段側の圧縮要素に吸入される冷媒の過熱度制御>
本変形例では、気液分離器としてのレシーバ18による中間圧インジェクションを伴う暖房運転において、何らかの原因で、気液分離器としてのレシーバ18に液冷媒が多量に溜まる運転条件になり、気液分離が困難な状況になると、第1後段側インジェクション管18cを通じてレシーバ18から後段側の圧縮要素2dに戻される冷媒に液冷媒が混じってしまうおそれがあり、これにより、中間圧インジェクションが行われた後における後段側の圧縮要素2dに吸入される中間圧の冷媒が湿り状態になってしまい、圧縮機構2の信頼性が損なわれてしまうおそれがある。
また、本変形例では、冷房運転時において、エコノマイザ熱交換器20による中間圧インジェクションが行われており、第2後段側インジェクション管19から後段側の圧縮要素2dに戻される冷媒の過熱度は、第2後段側インジェクション弁19aの開度調節によって目標値になるように制御されている。このため、本変形例では、冷房運転において、エコノマイザ熱交換器20による中間圧インジェクションにより後段側の圧縮要素2dに戻される冷媒の影響によって、後段側の圧縮要素2dに吸入される冷媒が湿り状態になるのを防ぐことができ、これにより、圧縮機構2の信頼性が向上している。
このように、本変形例では、中間冷却器7による冷却操作や中間圧インジェクションにより後段側の圧縮要素2dに戻される冷媒の影響によって、後段側の圧縮要素2dに吸入される冷媒が湿り状態になるのを防ぐことができ、これにより、冷房運転時及び暖房運転時のいずれにおいても、圧縮機構2の信頼性が向上している。
そして、この構成においては、ブリッジ回路17が省略されている点と、切換機構3を加熱運転状態にしている際には、熱源側熱交換器4と利用側熱交換器6との間を流れる冷媒が利用側膨張機構5c、レシーバ18、第1膨張機構5aの順に流れる点とが異なる(このため、図10、11における点Iと点Lとが入れ替わることになる)が、上述と同様の作用効果を得ることができる。
(7)変形例5
上述の実施形態及びその変形例では、1台の一軸二段圧縮構造の圧縮機21によって、2つの圧縮要素2c、2dのうちの前段側の圧縮要素から吐出された冷媒を後段側の圧縮要素で順次圧縮する二段圧縮式の圧縮機構2が構成されているが、三段圧縮式等のような二段圧縮式よりも多段の圧縮機構を採用してもよいし、また、単一の圧縮要素が組み込まれた圧縮機及び/又は複数の圧縮要素が組み込まれた圧縮機を複数台直列に接続することで多段の圧縮機構を構成してもよい。また、利用側熱交換器6が多数接続される場合等のように、圧縮機構の能力を大きくする必要がある場合には、多段圧縮式の圧縮機構を2系統以上並列に接続した並列多段圧縮式の圧縮機構を採用してもよい。
第1圧縮機構103は、本変形例において、2つの圧縮要素103c、103dで冷媒を二段圧縮する圧縮機29から構成されており、圧縮機構102の吸入母管102aから分岐された第1吸入枝管103a、及び、圧縮機構102の吐出母管102bに合流する第1吐出枝管103bに接続されている。第2圧縮機構104は、本変形例において、2つの圧縮要素104c、104dで冷媒を二段圧縮する圧縮機30から構成されており、圧縮機構102の吸入母管102aから分岐された第2吸入枝管104a、及び、圧縮機構102の吐出母管102bに合流する第2吐出枝管104bに接続されている。尚、圧縮機29、30は、上述の実施形態及びその変形例における圧縮機21と同様の構成であるため、圧縮要素103c、103d、104c、104dを除く各部を示す符号をそれぞれ29番台や30番台に置き換えることとし、ここでは、説明を省略する。そして、圧縮機29は、第1吸入枝管103aから冷媒を吸入し、この吸入された冷媒を圧縮要素103cによって圧縮した後に中間冷媒管8を構成する第1入口側中間枝管81に吐出し、第1入口側中間枝管81に吐出された冷媒を中間冷媒管8を構成する中間母管82及び第1出口側中間枝管83を通じて圧縮要素103dに吸入させて冷媒をさらに圧縮した後に第1吐出枝管103bに吐出するように構成されている。圧縮機30は、第1吸入枝管104aから冷媒を吸入し、この吸入された冷媒を圧縮要素104cによって圧縮した後に中間冷媒管8を構成する第2入口側中間枝管84に吐出し、第2入口側中間枝管84に吐出された冷媒を中間冷媒管8を構成する中間母管82及び第2出口側中間枝管85を通じて圧縮要素104dに吸入させて冷媒をさらに圧縮した後に第2吐出枝管104bに吐出するように構成されている。中間冷媒管8は、本変形例において、圧縮要素103d、104dの前段側に接続された圧縮要素103c、104cから吐出された冷媒を、圧縮要素103c、104cの後段側に接続された圧縮要素103d、104dに吸入させるための冷媒管であり、主として、第1圧縮機構103の前段側の圧縮要素103cの吐出側に接続される第1入口側中間枝管81と、第2圧縮機構104の前段側の圧縮要素104cの吐出側に接続される第2入口側中間枝管84と、両入口側中間枝管81、84が合流する中間母管82と、中間母管82から分岐されて第1圧縮機構103の後段側の圧縮要素103dの吸入側に接続される第1出口側中間枝管83と、中間母管82から分岐されて第2圧縮機構104の後段側の圧縮要素104dの吸入側に接続される第2出口側中間枝管85とを有している。また、吐出母管102bは、圧縮機構102から吐出された冷媒を切換機構3に送るための冷媒管であり、吐出母管102bに接続される第1吐出枝管103bには、第1油分離機構141と第1逆止機構142とが設けられており、吐出母管102bに接続される第2吐出枝管104bには、第2油分離機構143と第2逆止機構144とが設けられている。第1油分離機構141は、第1圧縮機構103から吐出される冷媒に同伴する冷凍機油を冷媒から分離して圧縮機構102の吸入側へ戻す機構であり、主として、第1圧縮機構103から吐出される冷媒に同伴する冷凍機油を冷媒から分離する第1油分離器141aと、第1油分離器141aに接続されており冷媒から分離された冷凍機油を圧縮機構102の吸入側に戻す第1油戻し管141bとを有している。第2油分離機構143は、第2圧縮機構104から吐出される冷媒に同伴する冷凍機油を冷媒から分離して圧縮機構102の吸入側へ戻す機構であり、主として、第2圧縮機構104から吐出される冷媒に同伴する冷凍機油を冷媒から分離する第2油分離器143aと、第2油分離器143aに接続されており冷媒から分離された冷凍機油を圧縮機構102の吸入側に戻す第2油戻し管143bとを有している。本変形例において、第1油戻し管141bは、第2吸入枝管104aに接続されており、第2油戻し管143cは、第1吸入枝管103aに接続されている。このため、第1圧縮機構103内に溜まった冷凍機油の量と第2圧縮機構104内に溜まった冷凍機油の量との間に偏りに起因して第1圧縮機構103から吐出される冷媒に同伴する冷凍機油の量と第2圧縮機構104から吐出される冷媒に同伴する冷凍機油の量との間に偏りが生じた場合であっても、圧縮機構103、104のうち冷凍機油の量が少ない方に冷凍機油が多く戻ることになり、第1圧縮機構103内に溜まった冷凍機油の量と第2圧縮機構104内に溜まった冷凍機油の量との間の偏りが解消されるようになっている。また、本変形例において、第1吸入枝管103aは、第2油戻し管143bとの合流部から吸入母管102aとの合流部までの間の部分が、吸入母管102aとの合流部に向かって下り勾配になるように構成されており、第2吸入枝管104aは、第1油戻し管141bとの合流部から吸入母管102aとの合流部までの間の部分が、吸入母管102aとの合流部に向かって下り勾配になるように構成されている。このため、圧縮機構103、104のいずれか一方が停止中であっても、運転中の圧縮機構に対応する油戻し管から停止中の圧縮機構に対応する吸入枝管に戻される冷凍機油は、吸入母管102aに戻ることになり、運転中の圧縮機構の油切れが生じにくくなっている。油戻し管141b、143bには、油戻し管141b、143bを流れる冷凍機油を減圧する減圧機構141c、143cが設けられている。逆止機構142、144は、圧縮機構103、104の吐出側から切換機構3への冷媒の流れを許容し、かつ、切換機構3から圧縮機構103、104の吐出側への冷媒の流れを遮断するための機構である。
中間冷却器7は、本変形例において、中間冷媒管8を構成する中間母管82に設けられており、第1圧縮機構103の前段側の圧縮要素103cから吐出された冷媒と第2圧縮機構104の前段側の圧縮要素104cから吐出された冷媒とが合流したものを冷却する熱交換器である。すなわち、中間冷却器7は、2つの圧縮機構103、104に共通の冷却器として機能するものとなっている。このため、多段圧縮式の圧縮機構103、104を複数系統並列に接続した並列多段圧縮式の圧縮機構102に対して中間冷却器7を設ける際の圧縮機構102周りの回路構成の簡素化が図られている。
そして、本変形例の構成においても、上述の実施形態及びその変形例と同様の作用効果を得ることができる。
また、図14に示されるように、上述の変形例4におけるブリッジ回路17を有しない冷媒回路710(図12参照)において、二段圧縮式の圧縮機構2に代えて、二段圧縮式の圧縮機構103、104を並列に接続した圧縮機構102を採用した冷媒回路910にしてもよい。
(8)他の実施形態
以上、本発明の実施形態及びその変形例について図面に基づいて説明したが、具体的な構成は、これらの実施形態及びその変形例に限られるものではなく、発明の要旨を逸脱しない範囲で変更可能である。
例えば、上述の実施形態及びその変形例において、利用側熱交換器6を流れる冷媒と熱交換を行う加熱源又は冷却源としての水やブラインを使用するとともに、利用側熱交換器6において熱交換された水やブラインと室内空気とを熱交換させる二次熱交換器を設けた、いわゆる、チラー型の空気調和装置に本発明を適用してもよい。
また、超臨界域で作動する冷媒としては、二酸化炭素に限定されず、エチレン、エタンや酸化窒素等を使用してもよい。
Claims (6)
- 複数の圧縮要素を有しており、前記複数の圧縮要素のうちの前段側の圧縮要素から吐出された冷媒を後段側の圧縮要素で順次圧縮するように構成された圧縮機構(2、102)と、
熱源側熱交換器(4)と、
利用側熱交換器(6)と、
前記前段側の圧縮要素から吐出された冷媒を前記後段側の圧縮要素に吸入させるための中間冷媒管(18)に設けられ、前記前段側の圧縮要素から吐出されて前記後段側の圧縮要素に吸入される冷媒の冷却器として機能する中間冷却器(7)と、
前記中間冷却器をバイパスするように前記中間冷媒管に接続されている中間冷却器バイパス管(9)とを備え、
前記中間冷却器の熱源温度又は前記中間冷却器の出口冷媒温度が前記前段側の圧縮要素から前記後段側の圧縮要素に送られる冷媒の飽和温度以下になった際に、前記中間冷却器バイパス管を用いて、前記中間冷却器に冷媒が流れないようにする湿り防止制御を行う、
冷凍装置(1)。 - 前記中間冷却器(7)は、空気を熱源とする熱交換器である、請求項1に記載の冷凍装置(1)。
- 前記中間冷却器(7)は、水を熱源とする熱交換器であり、
前記湿り防止制御では、さらに、前記中間冷却器への水の供給を止める、
請求項1に記載の冷凍装置(1)。 - 複数の圧縮要素を有しており、前記複数の圧縮要素のうちの前段側の圧縮要素から吐出された冷媒を後段側の圧縮要素で順次圧縮するように構成された圧縮機構(2、102)と、
熱源側熱交換器(4)と、
利用側熱交換器(6)と、
水を熱源とする熱交換器であって、前記前段側の圧縮要素から吐出された冷媒を前記後段側の圧縮要素に吸入させるための中間冷媒管(8)に設けられ、前記前段側の圧縮要素から吐出されて前記後段側の圧縮要素に吸入される冷媒の冷却器として機能する中間冷却器(7)とを備え、
前記中間冷却器の熱源温度又は前記中間冷却器の出口冷媒温度が前記前段側の圧縮要素から前記後段側の圧縮要素に送られる冷媒の飽和温度以下になった際に、前記中間冷却器を流れる水の流量を減少させる湿り防止制御を行う、
冷凍装置(1)。 - 前記湿り防止制御では、さらに、前記中間冷却器(7)の出口冷媒温度が前記前段側の圧縮要素から前記後段側の圧縮要素に送られる冷媒の飽和温度よりも高くなるように、前記中間冷却器を流れる水の流量を制御する、請求項4に記載の冷凍装置(1)。
- 前記熱源側熱交換器(4)と前記利用側熱交換器(6)との間を流れる冷媒を分岐して前記後段側の圧縮要素に戻すための後段側インジェクション管(18c、19)をさらに備えている、請求項1~5のいずれかに記載の冷凍装置(1)。
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- 2009-01-27 ES ES09705691.5T patent/ES2685433T3/es active Active
- 2009-01-27 EP EP09705691.5A patent/EP2251622B1/en active Active
- 2009-01-27 WO PCT/JP2009/051235 patent/WO2009096372A1/ja active Application Filing
- 2009-01-27 CN CN2009801035683A patent/CN101932891B/zh active Active
- 2009-01-27 US US12/864,539 patent/US20110005269A1/en not_active Abandoned
- 2009-01-27 AU AU2009210093A patent/AU2009210093B2/en active Active
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EP4040075A4 (en) * | 2019-09-30 | 2022-11-02 | Daikin Industries, Ltd. | AIR CONDITIONER |
Also Published As
Publication number | Publication date |
---|---|
CN101932891B (zh) | 2012-09-26 |
KR101157802B1 (ko) | 2012-06-22 |
ES2685433T3 (es) | 2018-10-09 |
EP2251622A1 (en) | 2010-11-17 |
KR20100113574A (ko) | 2010-10-21 |
EP2251622A4 (en) | 2017-03-29 |
JP5141269B2 (ja) | 2013-02-13 |
CN101932891A (zh) | 2010-12-29 |
AU2009210093A1 (en) | 2009-08-06 |
US20110005269A1 (en) | 2011-01-13 |
AU2009210093B2 (en) | 2011-09-15 |
EP2251622B1 (en) | 2018-08-01 |
JP2009180428A (ja) | 2009-08-13 |
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