WO2021065156A1 - Unité de source de chaleur et dispositif de réfrigération - Google Patents

Unité de source de chaleur et dispositif de réfrigération Download PDF

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Publication number
WO2021065156A1
WO2021065156A1 PCT/JP2020/027906 JP2020027906W WO2021065156A1 WO 2021065156 A1 WO2021065156 A1 WO 2021065156A1 JP 2020027906 W JP2020027906 W JP 2020027906W WO 2021065156 A1 WO2021065156 A1 WO 2021065156A1
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WIPO (PCT)
Prior art keywords
refrigerant
flow path
pipe
heat exchanger
refrigeration cycle
Prior art date
Application number
PCT/JP2020/027906
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English (en)
Japanese (ja)
Inventor
東 近藤
植野　武夫
貴仁 中山
孝将 伊東
覚 阪江
千晴 冨田
Original Assignee
ダイキン工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2019180679A external-priority patent/JP6849037B1/ja
Priority claimed from JP2019180683A external-priority patent/JP6787465B1/ja
Application filed by ダイキン工業株式会社 filed Critical ダイキン工業株式会社
Priority to CN202080061329.2A priority Critical patent/CN114341569B/zh
Priority to EP20871109.3A priority patent/EP4033178B1/fr
Publication of WO2021065156A1 publication Critical patent/WO2021065156A1/fr

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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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F25B41/22—Disposition of valves, e.g. of on-off valves or flow control valves between evaporator and compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
    • F25B2313/0234—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in series arrangements
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2509—Economiser valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2115—Temperatures of a compressor or the drive means therefor
    • F25B2700/21152—Temperatures of a compressor or the drive means therefor at the discharge side of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a condenser
    • F25B2700/21163—Temperatures of a condenser of the refrigerant at the outlet of the condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02—Defrosting cycles
    • F25B47/022—Defrosting cycles hot gas defrosting
    • F25B47/025—Defrosting cycles hot gas defrosting by reversing the cycle

Definitions

  • This disclosure relates to a heat source unit and a refrigerating device.
  • a refrigerating device equipped with a refrigerant circuit is known.
  • the refrigerant circuit of the refrigerating apparatus disclosed in Patent Document 1 includes a compressor, an air heat exchanger (heat source heat exchanger), an expansion valve, an internal heat exchanger (utilized heat exchanger), and a supercooler (overcooling heat). It is equipped with an exchanger).
  • a first refrigeration cycle and a second refrigeration cycle are performed.
  • the heat source heat exchanger serves as a radiator and the utilization heat exchanger serves as an evaporator.
  • the heat source heat exchanger serves as an evaporator and the utilization heat exchanger serves as a radiator.
  • the refrigerating device performs the first refrigerating cycle in the cooling operation.
  • the refrigerating device performs a defrost operation.
  • the defrost operation the second refrigeration cycle is performed, and the used heat exchanger becomes a radiator. Therefore, the refrigerant can melt the frost on the surface of the heat exchanger used.
  • the refrigerant radiated by the heat source heat exchanger is cooled by the overcooling heat exchanger and then evaporated by the utilization heat exchanger.
  • a refrigerant having a relatively high temperature flows into the supercooling heat exchanger from the utilization heat exchanger side.
  • the thermal stress of the supercooled heat exchanger increases, and the supercooled heat exchanger may cause stress cracking.
  • the object of the present disclosure is to suppress an increase in thermal stress of the supercooled heat exchanger when switching from the first refrigeration cycle to the second refrigeration cycle.
  • the first aspect comprises a heat source circuit (11) including a compression element (20), a heat source heat exchanger (14), a supercooling heat exchanger (40) and a switching mechanism (24), and a utilization heat exchanger (54).
  • the switching mechanism (24) dissipates heat from the first refrigeration cycle using the heat source heat exchanger (14) as a radiator and the utilization heat exchanger (54) as an evaporator, and the utilization heat exchanger (54). It is configured to switch between a second refrigeration cycle that uses the heat source heat exchanger (14) as an evaporator and the heat source heat exchanger (14) as an evaporator.
  • the supercooled heat exchanger (40) has a first flow path (40a) connected in the middle of a liquid pipe (32, 33) through which the liquid refrigerant of the heat source circuit (11) flows, and the first flow path (40a). It has a second flow path (40b) through which a heat medium for cooling the refrigerant flowing in 40a) flows.
  • an adjusting mechanism for performing a first operation for reducing the cooling capacity of the second flow path (40b) for the refrigerant in the first flow path (40a) is provided. I have.
  • the first operation reduces the cooling capacity of the second flow path (40b). Thereby, the temperature of the first flow path (40a) can be raised. As a result, in the second refrigeration cycle, even if the high-temperature refrigerant flows into the first flow path (40a) from the utilization heat exchanger (54) side, the increase in thermal stress of the supercooling heat exchanger (40) is suppressed. it can.
  • the switching mechanism (24) switches to the second refrigeration cycle when the temperature of the refrigerant flowing through the first flow path (40a) becomes higher than a predetermined value during the first operation.
  • the first refrigeration cycle is switched to the second refrigeration cycle.
  • the heat source circuit (11) has one end branched from the liquid pipe (32, 33) and the other end communicating with the intermediate pressure portion or the suction portion of the compression element (20), and the heat.
  • An injection circuit (60) including the second flow path (40b) through which a refrigerant as a medium flows, and an expansion valve (26) connected to the upstream side of the second flow path (40b) in the injection circuit (60).
  • the adjusting mechanism (80) controls the opening degree of the expansion valve (26) and the expansion valve (26) so as to reduce the cooling capacity in the first operation. And include.
  • the cooling capacity of the second flow path (40b) can be reduced by controlling the opening degree of the expansion valve (26).
  • the refrigerant in the second flow path (40b) can be introduced into the compression element (20) via the injection circuit (60).
  • control unit (101) reduces the opening degree of the expansion valve (26) so as to reduce the flow rate of the refrigerant in the second flow path (40b) in the first operation. Take control.
  • the flow rate of the refrigerant flowing into the second flow path (40b) is reduced by the first control.
  • the cooling capacity of the second flow path (40b) can be reduced.
  • control unit (101) increases the opening degree of the expansion valve (26) so as to increase the pressure of the refrigerant in the second flow path (40b) in the first operation. 2 Control is performed.
  • the pressure of the refrigerant flowing into the second flow path (40b) is increased by the second control.
  • the cooling capacity of the second flow path (40b) can be reduced.
  • the second mode when the control unit (101) satisfies the condition indicating that the discharge temperature, which is the temperature of the refrigerant discharged from the compression element (20), is low in the first operation, the second mode is satisfied.
  • the first control for reducing the opening degree of the expansion valve (26) is performed so as to reduce the flow rate of the refrigerant in the flow path (40b) and the condition indicating that the discharge temperature of the compression element (20) is high is satisfied.
  • the second control is performed to increase the opening degree of the expansion valve (26) so as to increase the pressure of the refrigerant in the second flow path (40b).
  • the first control when the discharge temperature is low, the first control is performed.
  • the second control is performed.
  • the second control By the second control, the temperature of the refrigerant discharged from the compression element (20) can be lowered.
  • the heat source circuit (11) has a flow rate adjusting valve (28, 29) connected to the downstream side of the second flow path (40b) in the injection circuit (60).
  • the opening degree of the flow rate adjusting valve (28, 29) is adjusted so that the discharge temperature of the refrigerant discharged from the compression element (20) approaches a predetermined value.
  • the flow rate adjusting valves (28, 29) can adjust the amount of refrigerant introduced into the compression element (20) by adjusting the opening degree thereof. Thereby, the discharge temperature of the compression element (20) can be adjusted.
  • the eighth aspect is in any one of the first to seventh aspects.
  • a supercooled heat exchanger (40) having the first flow path (40a) and the second flow path (40b),
  • a bypass flow path (70) configured so that at least a part of the refrigerant dissipated by the utilization heat exchanger (54) bypasses the first flow path (40a).
  • it has a flow path switching mechanism (180) that limits the flow of the refrigerant in the first flow path (40a) and allows the flow of the refrigerant in the bypass flow path (70).
  • the flow rate of the refrigerant flowing through the first flow path can be reduced in the second refrigeration cycle. Therefore, an increase in thermal stress of the supercooled heat exchanger (40) can be suppressed.
  • the ninth aspect is in any one of the first to eighth aspects.
  • the compression element (20) has a first compression unit (22, 23) and a second compression unit (21), and is a refrigerant compressed by the first compression unit (22, 23) in the first refrigeration cycle. Is a two-stage compression type that further compresses with the second compression unit (21).
  • the tenth aspect is a refrigerating apparatus including a heat source unit (10) according to any one of the first to ninth aspects and a utilization unit (50) having a utilization heat exchanger (54).
  • the eleventh aspect is the tenth aspect.
  • the refrigerant circuit (2) is used in the defrost operation for defrosting the utilization heat exchanger (54).
  • the second refrigeration cycle is performed.
  • FIG. 1 is a piping system diagram of the refrigerating device according to the embodiment.
  • FIG. 2 is a block diagram showing the relationship between the controller, various sensors, and the constituent devices of the refrigerant circuit.
  • FIG. 3 is a diagram corresponding to FIG. 1 showing the flow of the refrigerant in the cooling operation.
  • FIG. 4 is a diagram corresponding to FIG. 1 showing the flow of the refrigerant in the defrost operation.
  • FIG. 5 is a flowchart of the first operation.
  • FIG. 6 is a piping system diagram of the refrigerating apparatus according to the first modification.
  • FIG. 7 is a diagram corresponding to FIG. 5 of the first operation according to the first modification.
  • FIG. 8 is a piping system diagram of the refrigerating apparatus according to the second modification.
  • FIG. 9 is a piping system diagram of the refrigerating apparatus according to the third modification.
  • FIG. 10 is a diagram corresponding to FIG. 9 showing the flow of the refrigerant in the cooling operation.
  • FIG. 11 is a diagram corresponding to FIG. 9 showing the flow of the refrigerant in the defrost operation.
  • FIG. 12 is an enlarged piping system diagram of the supercooling heat exchanger of the refrigerating apparatus according to the modified example 4 and its peripheral structure.
  • FIG. 13 is a diagram corresponding to FIG. 12 showing the flow of the refrigerant in the cooling operation.
  • FIG. 14 is a diagram corresponding to FIG. 12 showing the flow of the refrigerant in the defrost operation.
  • FIG. 10 is a diagram corresponding to FIG. 9 showing the flow of the refrigerant in the cooling operation.
  • FIG. 11 is a diagram corresponding to FIG. 9 showing the flow of the refrigerant in the defrost operation.
  • FIG. 12 is an enlarged
  • FIG. 15 is a piping system diagram of the refrigerating apparatus according to the modified example 5.
  • FIG. 16 is FIG. 12 of a refrigerating apparatus according to another embodiment.
  • FIG. 17 is FIG. 12 of a refrigerating apparatus according to another embodiment.
  • FIG. 18 is FIG. 12 of a refrigerating apparatus according to another embodiment.
  • the freezing device (1) cools the air in the freezing warehouse.
  • the refrigerating apparatus (1) includes an outdoor unit (10) and an internal unit (50).
  • the outdoor unit (10) is a heat source unit (10) and is installed outdoors.
  • the internal unit (50) is a utilization unit (50).
  • the outdoor unit (10) is equipped with a heat source circuit (11).
  • the internal unit (50) includes a utilization circuit (51).
  • the refrigerant circuit (2) is configured by connecting the heat source circuit (11) and the utilization circuit (51) to each other via the connecting pipes (3, 4).
  • a vapor compression refrigeration cycle is performed by circulating the refrigerant.
  • the heat source circuit (11) and the utilization circuit (51) are connected to each other by the liquid communication pipe (3) and the gas communication pipe (4).
  • One end of the liquid communication pipe (3) is connected to a liquid side closing valve (17) connected to one end of the heat source circuit (11).
  • One end of the gas connecting pipe (4) is connected to a gas side closing valve (18) connected to the other end of the heat source circuit (11).
  • the outdoor unit (10) has an outdoor fan (15), a heat source circuit (11), and an adjustment mechanism (80).
  • the heat source circuit (11) has a compression element (20), a four-way switching valve (24), an outdoor heat exchanger (14), a liquid receiver (39), and a supercooled heat exchanger (40). ..
  • the compression element (20) compresses the refrigerant, which is a heat medium.
  • the compression element (20) constitutes a two-stage compression type in which the refrigerant compressed by the first compression unit (22, 23) on the lower stage side is further compressed by the second compression unit (21) on the higher stage side.
  • the first compression unit (22, 23) is a first low-stage compressor (22) and a second low-stage compressor (23).
  • the second compression unit (21) is a high-stage compressor (21).
  • the first low-stage compressor (22) and the second low-stage compressor (23) are connected in parallel with each other.
  • Each compressor (21 to 23) is composed of a fully enclosed high-pressure dome type scroll compressor.
  • Each compressor (21 to 23) is connected to a compression mechanism (not shown) and an electric motor (not shown) that drives the compression mechanism.
  • An inverter that can freely change the rotation speed of the electric motor within a predetermined range is connected to the electric motors of the high-stage compressor (21) and the second low-stage compressor (23). With this inverter, the rotation speed of the electric motor can be adjusted to increase or decrease the operating capacity of the high-stage compressor (21) and the second low-stage compressor (23).
  • the inverter is not connected to the electric motor of the first low-stage compressor (22). Therefore, the operating capacity of the first low-stage compressor (22) is fixed.
  • the first low-stage compressor (22) rotates at a constant rotation speed.
  • the first suction pipe (44) and the first discharge pipe (41) are connected to the high-stage compressor (21).
  • a first check valve (CV1) is connected to the first discharge pipe (41).
  • the first check valve (CV1) allows the flow of refrigerant from the discharge end of the high-stage compressor (21) to the four-way switching valve (24) described later, while prohibiting the opposite flow.
  • a second suction pipe (45) and a second discharge pipe (42) are connected to the first low-stage compressor (22).
  • a second check valve (CV2) is connected to the second discharge pipe (43).
  • the second check valve (CV2) allows the flow of refrigerant from the discharge end of the first low-stage compressor (22) to the second confluence pipe (47), which will be described later, while prohibiting the opposite flow. ..
  • a third suction pipe (46) and a third discharge pipe (43) are connected to the second low-stage compressor (23).
  • a third check valve (CV3) is connected to the third discharge pipe (43).
  • the third check valve (CV3) allows the flow of refrigerant from the discharge end of the second low-stage compressor (23) to the second confluence pipe (47), which will be described later, while prohibiting the opposite flow. ..
  • the second suction pipe (45) and the third suction pipe (46) are connected to the first confluence pipe (48).
  • the second discharge pipe (42) and the third discharge pipe (43) are connected to the second confluence pipe (47).
  • the heat source circuit (11) is provided with a connecting pipe (49) having one end connected in the middle of the first merging pipe (48) and the other end connected in the middle of the second merging pipe (47).
  • a sixth electric valve (53) is connected to the connecting pipe (49).
  • the sixth electric valve (53) is a flow rate adjusting valve.
  • the sixth electric valve (53) regulates the flow rate of the refrigerant in the connecting pipe (49).
  • the four-way switching valve (24) constitutes a switching mechanism for switching the flow path of the refrigerant.
  • the four-way switching valve (24) includes first to fourth ports (P1 to P4).
  • the first port (P1) is connected to the first discharge pipe (41) of the high-stage compressor (21).
  • the second port (P2) is connected to the first suction pipe (44).
  • the third port (P3) communicates with the gas end of the outdoor heat exchanger (14).
  • the fourth port (P4) is connected to the second confluence pipe (47).
  • the four-way switching valve (24) is configured to be switchable between the first state (the state shown by the solid line in FIG. 1) and the second state (the state shown by the broken line in FIG. 1).
  • the first state the second port (P2) and the fourth port (P4) communicate with each other, and the first port (P1) and the third port (P3) communicate with each other.
  • the second state the second port (P2) and the third port (P3) communicate with each other, and the first port (P1) and the fourth port (P4) communicate with each other.
  • the outdoor heat exchanger (14) is a heat source heat exchanger (14).
  • the outdoor heat exchanger (14) is a fin-and-tube type air heat exchanger.
  • the outdoor fan (15) is located near the outdoor heat exchanger (14).
  • the outdoor fan (15) carries outdoor air.
  • the outdoor heat exchanger (14) exchanges heat between the refrigerant flowing inside the outdoor heat exchanger (14) and the outdoor air carried by the outdoor fan (15).
  • the gas end of the outdoor heat exchanger (14) communicates with the third port (P3) of the four-way switching valve (24).
  • the liquid end of the outdoor heat exchanger (14) is connected to one end of the first pipe (31).
  • the liquid receiver (39) constitutes a container for storing the refrigerant.
  • the receiver (39) separates the refrigerant into a gas refrigerant and a liquid refrigerant.
  • the supercooled heat exchanger (40) has a first flow path (40a) and a second flow path (40b).
  • the first flow path (40a) is connected in the middle of the liquid pipes (32, 33) through which the liquid refrigerant flows.
  • the second flow path is a flow path for cooling the refrigerant flowing through the first flow path (40a).
  • the refrigerant flowing through the first flow path (40a) and the refrigerant flowing through the second flow path (40b) exchange heat.
  • the first pipe (31) is connected between the liquid end of the outdoor heat exchanger (14) and the top of the liquid receiver (39).
  • a fourth outdoor check valve (CV4) is connected to the first pipe (31).
  • the fourth outdoor check valve (CV4) allows the flow of refrigerant from the outdoor heat exchanger (14) to the receiver (39) side, and prohibits the reverse flow of refrigerant.
  • a second pipe (32) is connected between the bottom of the liquid receiver (39) and one end of the first flow path (40a) of the supercooled heat exchanger (40).
  • the second pipe (32) forms a part of the liquid pipe.
  • the third pipe (33) is connected between the other end of the first flow path (40a) and the liquid side closing valve (17).
  • the third pipe (33) constitutes a part of the liquid pipe.
  • a fifth outdoor check valve (CV5) is connected to the third pipe (33).
  • the fifth outdoor check valve (CV5) allows the flow of refrigerant from the first flow path (40a) to the internal heat exchanger (54) side, and prohibits the reverse flow of refrigerant.
  • the fourth pipe (34) is connected to the third pipe (33).
  • One end of the fourth pipe (34) is connected between the fifth outdoor check valve (CV5) and the liquid side closing valve (17) in the third pipe (33).
  • the other end of the fourth pipe (34) is connected between the fourth outdoor check valve (CV4) and the liquid receiver (39) in the first pipe (31).
  • a sixth outdoor check valve (CV6) is connected to the fourth pipe (34).
  • the sixth outdoor check valve (CV6) allows the flow of refrigerant from the internal heat exchanger (54) side to the outdoor heat exchanger (14) side, and prohibits the reverse flow of refrigerant.
  • the fifth pipe (35) is connected to the second pipe (32). One end of the fifth pipe (35) is connected in the middle of the second pipe (32). The other end of the fifth pipe (35) is connected between the fourth outdoor check valve (CV4) in the first pipe (31) and the outdoor heat exchanger (14).
  • An outdoor expansion valve (25) is connected to the fifth pipe (35).
  • the outdoor expansion valve (25) is an electronic expansion valve having a variable opening degree.
  • a seventh outdoor check valve (CV7) is connected to the fifth pipe (35).
  • the seventh outdoor check valve (CV7) is provided between the connection portion between the first pipe (31) and the fifth pipe (35) and the outdoor expansion valve (25).
  • the seventh outdoor check valve (CV7) allows the flow of refrigerant from the internal heat exchanger (54) side to the outdoor heat exchanger (14) side, and prohibits the reverse flow of refrigerant.
  • the heat source circuit (11) includes an injection circuit (60).
  • the injection circuit (60) introduces the intermediate pressure refrigerant of the liquid pipes (32, 33) into the compression element (20).
  • One end of the injection circuit (60) branches from the liquid pipe (32, 33), and the other end communicates with the intermediate pressure portion of the compression element (20).
  • the injection circuit (60) includes a second flow path (40b), one first branch pipe (61), one relay pipe (62), and three injection pipes (63, 64, 65). ..
  • the inflow end of the first branch pipe (61) is connected between the connection portion of the fourth pipe (34) in the third pipe (33) and the liquid side closing valve (17).
  • the outflow end of the first branch pipe (61) is connected to the inflow end of the second flow path (40b) of the supercooled heat exchanger (40).
  • An injection valve (26) is connected to the first branch pipe (61).
  • the injection valve (26) is an expansion valve (26) having a variable opening degree.
  • the injection valve (26) is composed of an electronic expansion valve.
  • the inflow end of the relay pipe (62) is connected to the outflow end of the second flow path (40b).
  • the outflow portion of the relay pipe (62) is connected to each inflow end of the first injection pipe (63), the second injection pipe (64), and the third injection pipe (65).
  • the outflow end of the first injection pipe (63) communicates with the compression chamber of the high-stage compressor (21).
  • the outflow end of the second injection pipe (64) communicates with the compression chamber of the first low-stage compressor (22).
  • the outflow end of the third injection pipe (65) communicates with the compression chamber of the second lower stage compressor (23).
  • the first electric valve (27) is connected to the first injection pipe (63).
  • a second electric valve (28) is connected to the second injection pipe (64).
  • a third electric valve (29) is connected to the third injection pipe (65).
  • the first to third electric valves (27 to 29) are flow rate adjusting valves.
  • the first to third electric valves (27 to 29) regulate the flow rate of the refrigerant in the corresponding injection pipes (63 to 65).
  • the bypass flow path (70) is composed of a fourth pipe (34).
  • the bypass flow path (70) may include a first pipe (31), a second pipe (32) and a fifth pipe (35). Further, the bypass flow path (70) may include a receiver (39).
  • the bypass flow path (70) is connected in parallel with the supercooling heat exchanger (40).
  • the refrigerant in the bypass flow path (70) bypasses the supercooled heat exchanger (40).
  • the refrigerant radiated by the internal heat exchanger (54) is the fourth pipe (34), the first pipe (31), the receiver (39), and the second pipe (32). ) And the fifth pipe (35).
  • the flow path switching mechanism (180) includes a sixth outdoor check valve (CV6) and a fifth outdoor check valve (CV5).
  • the flow path switching mechanism (180) may include a fourth outdoor check valve (CV4) and a seventh outdoor check valve (CV7).
  • the flow path switching mechanism (180) limits the flow of the refrigerant in the first flow path (40a) and allows the flow of the refrigerant in the bypass flow path (70) in the second refrigeration cycle. Specifically, the flow path switching mechanism (180) prohibits the flow of the refrigerant in the first flow path (40a) and allows the flow of the refrigerant in the bypass flow path (70) in the second refrigeration cycle. The flow path switching mechanism (180) allows the flow of the refrigerant in the first flow path (40a) and prohibits the flow of the refrigerant in the bypass flow path (70) in the first refrigeration cycle.
  • the seventh outdoor check valve (CV7) the refrigerant flowing from the outdoor heat exchanger (14) into the first pipe (31) flows through the fifth pipe (35). Prohibit doing.
  • the sixth outdoor check valve (CV6) prohibits the refrigerant flowing from the outdoor heat exchanger (14) into the first pipe (31) from flowing through the fourth pipe (34).
  • the outdoor expansion valve (25) is fully open. Therefore, the outdoor expansion valve (25) allows the refrigerant to flow into the first flow path (40a).
  • the fifth outdoor check valve (CV5) prohibits the refrigerant from flowing through the first flow path (40a).
  • the sixth outdoor check valve (CV6) allows the refrigerant to flow through the fourth pipe (34).
  • the fourth outdoor check valve (CV4) prohibits the refrigerant flowing from the fourth pipe (34) into the first pipe (31) from flowing to the outdoor heat exchanger (14) side. ..
  • the outdoor expansion valve (25) depressurizes the refrigerant. Thereby, the outdoor expansion valve (25) allows the refrigerant to flow from the second pipe (32) to the fifth pipe (35).
  • the seventh outdoor check valve (CV7) allows the refrigerant to flow through the fifth pipe (35).
  • the pressure of the refrigerant on the downstream side of the 5th outdoor check valve (CV5) is higher than the pressure of the refrigerant on the upstream side of the 5th outdoor check valve (CV5). This is because the pressure of the refrigerant in the first flow path (40a) corresponds to the pressure of the refrigerant decompressed by the outdoor expansion valve (25). Therefore, the refrigerant in the first flow path (40a) does not pass through the fifth outdoor check valve (CV5).
  • the first to third discharge pipes (41 to 43) are provided with the first to third discharge temperature sensors (71 to 73).
  • the first discharge temperature sensor (71) detects the first discharge temperature (Td1) of the refrigerant discharged from the high-stage compressor (21).
  • the second discharge temperature sensor (72) detects the second discharge temperature (Td2) of the refrigerant discharged from the first low-stage compressor (22).
  • the third discharge temperature sensor (73) detects the third discharge temperature (Td3), which is the temperature of the refrigerant discharged from the second low-stage compressor (23).
  • a liquid temperature sensor (74) is provided in the third pipe (33).
  • the liquid temperature sensor (74) detects the temperature (TL) of the refrigerant flowing through the third pipe (33).
  • the first branch pipe (61) is provided with a first temperature sensor (75).
  • the first temperature sensor (75) is arranged between the injection valve (26) and the second flow path (40b).
  • the first temperature sensor (75) detects the temperature (Tg1) of the refrigerant flowing into the second flow path (40b).
  • a second temperature sensor (76) is provided on the relay pipe (62).
  • the second temperature sensor (76) is arranged closer to the second flow path (40b).
  • the second temperature sensor (76) detects the temperature (Tg2) of the refrigerant immediately after flowing out from the second flow path (40b) to the relay pipe (62).
  • a pressure sensor (77) is provided on the relay pipe (62).
  • the pressure sensor (77) detects the pressure (MP) of the refrigerant in the relay pipe (62).
  • the internal unit (50) is a utilization unit.
  • the internal unit (50) has a utilization circuit (51) and an internal fan (52).
  • the utilization circuit (51) is connected to the liquid communication pipe (3) and the gas communication pipe (4).
  • the utilization circuit (51) has a heating pipe (55), an internal expansion valve (30), and an internal heat exchanger (54) in this order from the liquid end portion to the gas end portion.
  • the heating pipe (55) is attached to the drain pan (59) connected below the internal heat exchanger (54).
  • the drain pan (59) collects the condensed water dripping from the internal heat exchanger (54).
  • the heating pipe (55) warms the drain pan (59) and suppresses freezing of the drain water.
  • the internal expansion valve (30) is a temperature-sensitive expansion valve having a temperature-sensitive cylinder.
  • the opening of the internal expansion valve (30) is adjusted based on the refrigerant temperature on the outlet side of the internal heat exchanger (54). ..
  • the internal heat exchanger (54) functions as a radiator, the internal expansion valve (30) is fully closed.
  • the internal heat exchanger (54) constitutes a utilization heat exchanger.
  • the internal heat exchanger (54) is a fin-and-tube type heat exchanger that exchanges heat between the refrigerant and the internal air.
  • the internal fan (52) is arranged in the vicinity of the internal heat exchanger (54).
  • the internal fan (52) is the internal heat exchanger (54). ) Is supplied with air inside the refrigerator.
  • the utilization circuit (51) has an internal bypass flow path (58) that bypasses the internal expansion valve (30).
  • An internal check valve (CV8) is connected to the internal bypass flow path (58). The internal check valve (CV8) allows the flow of refrigerant from the internal heat exchanger (54) to the heating pipe (55) and prohibits the reverse flow.
  • the controller (100) which is a control unit, includes a microcomputer mounted on a control board and a memory device (specifically, a semiconductor memory) for storing software for operating the microcomputer.
  • the controller (100) controls various devices of the refrigerating device (1) based on the detection signals of various sensors.
  • the controller (100) has an outdoor controller (101) provided in the outdoor unit (10) and an internal controller (102) provided in the internal unit (50).
  • the outdoor controller (101) can communicate with the internal controller (102).
  • the outdoor controller (101) which is a control unit, includes the first to third discharge temperature sensors (71 to 73), the liquid temperature sensor (74), the first to second temperature sensors (75,76), and the pressure sensor (77). ) And other sensors are connected by communication lines.
  • the outdoor controller (101) is connected to the components of the refrigerant circuit (2) including the injection valve (26), the first to third electric valves (27 to 29), and the outdoor fan (15) by a communication line. There is.
  • the internal controller (102) is connected to the components of the refrigerant circuit (2) including the internal expansion valve (30) and the internal fan (52) by a communication line.
  • the outdoor controller (101) receives a signal from the internal controller (102) and controls the four-way switching valve (24) so as to switch between the first refrigeration cycle and the second refrigeration cycle.
  • the first refrigeration cycle is a refrigeration cycle in which the outdoor heat exchanger (14) is used as a radiator and the internal heat exchanger (54) is used as an evaporator.
  • a freezing operation is performed to cool the air in the refrigerator.
  • the second refrigeration cycle is performed.
  • the second refrigeration cycle is a refrigeration cycle in which the internal heat exchanger (54) is used as a radiator and the outdoor heat exchanger (14) is used as an evaporator.
  • a defrost operation is performed to remove the frost adhering to the internal heat exchanger (54).
  • the regulating mechanism (80) has an injection valve (26) and a controller (100).
  • the adjusting mechanism (80) performs a first operation of reducing the cooling capacity of the first flow path (40b) for the refrigerant of the second flow path (40b) before switching from the first refrigeration cycle to the second refrigeration cycle. ..
  • the controller (100) controls the opening degree of the injection valve (26) so as to reduce the cooling capacity in the first operation.
  • the cooling capacity is represented by, for example, a value obtained by multiplying the ratio enthalpy difference of the refrigerant at the outlet and the inlet of the second flow path (40b) by the flow rate of the refrigerant flowing through the second flow path (40b).
  • the four-way switching valve (24) switches from the first state to the second state.
  • the switching mechanism (24) switches from the first refrigeration cycle to the second refrigeration cycle.
  • This predetermined value is the target temperature (target TL) of the refrigerant that flows in from the first flow path (40a) and flows through the third pipe (33) in the first state. Details of the target temperature (target TL) will be described later.
  • each compressor (21 to 23), an outdoor fan (15), and an internal fan (52) are operated.
  • the four-way switching valve (24) is set to the first state, and the outdoor expansion valve (25) is fully closed.
  • the opening degrees of the internal expansion valve (30), the injection valve (26), and the first to third electric valves (27 to 29) are appropriately adjusted.
  • the sixth electric valve (53) is fully closed, and no refrigerant flows through the connecting pipe (49).
  • the four-way switching valve (24) is in the first state.
  • the first refrigeration cycle is performed in which the outdoor heat exchanger (14) is used as a condenser (radiator) and the internal heat exchanger (54) is used as an evaporator.
  • the refrigerant compressed by the first low-stage compressor (22) and the second low-stage compressor (23) flows through the second confluence pipe (47).
  • This refrigerant passes through the four-way switching valve (24) and the first suction pipe (44) and is introduced into the compression chamber of the high-stage compressor (21).
  • the high-pressure refrigerant compressed by the high-stage compressor (21) passes through the first discharge pipe (41) and the four-way switching valve (24) and flows into the outdoor heat exchanger (14).
  • the refrigerant dissipates heat to the outdoor air.
  • the refrigerant dissipated by the outdoor heat exchanger (14) flows through the first pipe (31).
  • the 7th outdoor check valve (CV7) and the 6th outdoor check valve (CV6) allow the flow of refrigerant in the 5th pipe (35) and 4th pipe (34), which are part of the bypass flow path (70). Be restricted. Therefore, this refrigerant flows into the liquid receiver (39) and passes through the first flow path (40a) of the second pipe (32) and the supercooling heat exchanger (40).
  • the injection valve (26) When the injection valve (26) is opened, a part of the refrigerant in the third pipe (33) flows through the first branch pipe (61).
  • the refrigerant in the first branch pipe (61) is decompressed by the injection valve (26) and then flows through the second flow path (40b) of the supercooling heat exchanger (40).
  • the refrigerant in the second flow path (40b) and the refrigerant in the first flow path (40a) exchange heat.
  • the refrigerant in the second flow path (40b) absorbs heat from the refrigerant in the first flow path (40a) and evaporates. As a result, the refrigerant in the first flow path (40a) is cooled, and the degree of supercooling of this refrigerant increases.
  • the refrigerant flowing through the second flow path is introduced from each injection pipe (63 to 65) into the compression chamber of each compressor (21 to 23) via the relay pipe (62).
  • the refrigerant cooled in the first flow path (40a) flows through the third pipe (33) and the liquid communication pipe (3), and is sent to the internal unit (50).
  • the refrigerant passes through the heating pipe (55) and is depressurized by the internal expansion valve (30). This refrigerant flows into the internal heat exchanger (54), absorbs heat from the internal air, and evaporates. As a result, the air inside the refrigerator is cooled.
  • the refrigerant evaporated in the internal heat exchanger (54) flows through the gas connecting pipe (4) and is sent to the outdoor unit (10).
  • This refrigerant flows through the first confluence pipe (48) and is sucked into the first low-stage compressor (22) and the second low-stage compressor (23), respectively.
  • a cooling operation for maintaining the inside of the freezing warehouse at a set temperature is performed.
  • ⁇ Defrost operation> In the defrost operation, the high-stage compressor (21) and the outdoor fan (15) are operated, and the internal fan (52) is stopped. The four-way switching valve (24) is set to the second state, and the internal expansion valve (30) is fully closed. The sixth electric valve (53) is fully opened. In the defrost operation, the refrigerant may flow through the injection circuit (60) as in the cooling operation. It is not necessary to fully close the injection valve (26) and let the refrigerant flow through the injection circuit (60).
  • the four-way switching valve (24) is in the second state.
  • a second refrigeration cycle is performed in which the outdoor heat exchanger (14) is used as an evaporator and the internal heat exchanger (54) is used as a condenser (radiator).
  • the refrigerant compressed by the high-stage compressor (21) is connected to the first discharge pipe (41), the four-way switching valve (24), the second confluence pipe (47), and the connection. It flows in the order of pipe (49) and first confluence pipe (48).
  • This refrigerant passes through the gas connecting pipe (4) and is sent to the internal unit (50).
  • the refrigerant flows through the internal heat exchanger (54).
  • the refrigerant melts the frost on the surface.
  • the refrigerant radiated by the internal heat exchanger (54) flows through the internal bypass flow path (58) and the heating pipe (55). This refrigerant flows through the liquid communication pipe (3) and is sent to the outdoor unit (10).
  • the refrigerant of the outdoor unit (10) flows into the third pipe (33) to the fourth pipe (34).
  • This refrigerant flows in the order of the first pipe (31), the receiver (39), and the second pipe (32).
  • this refrigerant is depressurized by the outdoor expansion valve (25).
  • the inflow of this refrigerant into the first flow path (40a) is suppressed. This is because, as described above, the differential pressure before and after the fifth outdoor check valve (CV5) prohibits the flow of the refrigerant in the fifth outdoor check valve (CV5).
  • the refrigerant flowing through the fifth pipe (35) flows into the outdoor heat exchanger (14) after passing through the first pipe (31).
  • the low-pressure refrigerant exchanges heat with the outdoor air and evaporates.
  • the refrigerant evaporated in the outdoor heat exchanger (14) passes through the four-way switching valve (24) and the first suction pipe (44) and is introduced into the compression chamber of the high-stage compressor (21). By circulating the refrigerant in this way, a defrost operation is performed to remove the frost adhering to the internal heat exchanger (54).
  • the refrigerating apparatus (1) provided with the overcooling heat exchanger (40) connected between the flow path of the outdoor heat exchanger (14) and the flow path of the internal heat exchanger (54), the first When the refrigeration cycle is switched to the second refrigeration cycle, the relatively high temperature flows into the flow path (first flow path (40a)) of the supercooling heat exchanger (40) from the internal heat exchanger (54) side. Refrigerant flows in.
  • the first flow path (40a) Since the first flow path (40a) is cooled in the first refrigeration cycle, when a high-temperature refrigerant suddenly flows into the first flow path (40a), the thermal stress of the supercooling heat exchanger (40) due to the temperature difference. Increases. As a result, the supercooled heat exchanger (40) may be damaged.
  • the refrigerant does not continuously flow through the first flow path (40a). Since the pressure of the refrigerant on the outlet side of the fifth outdoor check valve (CV5) is higher than the pressure of the refrigerant on the inlet side of the fifth outdoor check valve (CV5), the first flow path (40a) to the third pipe The continuous flow of refrigerant to (33) is prohibited. This is because the pressure of the refrigerant in the first flow path (40a) corresponds to the pressure of the refrigerant decompressed by the outdoor expansion valve (25).
  • the refrigerating apparatus (1) of the present embodiment is used before switching from the first refrigerating cycle to the second refrigerating cycle in order to suppress an increase in thermal stress of the first flow path (40a). Perform the following operations.
  • the first operation will be described in detail. If the condition for starting the defrost operation is satisfied during the cooling operation, the internal controller (102) transmits a defrost request signal.
  • the outdoor controller (101) receives the defrost operation request.
  • the outdoor controller (101) which is the adjustment mechanism (80), executes the first operation. Specifically, in the first operation, the outdoor controller (101) controls the injection valve (26) and the second to third electric valves (28, 29).
  • step ST1 when a command to execute the first operation is input to the outdoor controller (101), in step ST1, the outdoor controller (101) sets the current opening degree (Pls1) of the injection valve (26).
  • step ST2 the outdoor controller (101) determines whether or not the condition indicating that the discharge temperature of the compression element (20) is high is satisfied. Specifically, the outdoor controller (101) has a second discharge temperature (Td2) of the first low-stage compressor (22) and a third discharge temperature (Td3) of the second low-stage compressor (23). It is determined whether or not the condition indicating that both are high is satisfied. More specifically, in step ST2, the outdoor controller (101) determines whether or not the following conditions a) and b) are satisfied.
  • the second discharge temperature (Td2) of the first low-stage compressor (22) is lower than the predetermined value.
  • This predetermined value is, for example, 95 ° C.
  • the third discharge temperature (Td3) of the second lower stage compressor (23) is lower than the predetermined value.
  • This predetermined value is, for example, 95 ° C.
  • step ST2 if both the above conditions a) and b) are satisfied, the process proceeds to step ST3. If at least one of the above conditions a) and b) is not satisfied in step ST2, the process proceeds to steps ST4 to ST6.
  • step ST3 the outdoor controller (101) performs the first control to reduce the opening degree of the injection valve (26) so as to reduce the flow rate of the refrigerant in the second flow path (40b).
  • the first control reduces the flow rate of the refrigerant flowing through the second flow path (40b). Therefore, the amount of heat exchanged between the refrigerant in the second flow path (40b) and the refrigerant in the first flow path (40a) is reduced.
  • the cooling capacity of the second flow path (40b) for the refrigerant in the first flow path (40a) is reduced.
  • the temperature of the refrigerant flowing through the first flow path (40a) rises, and the temperature (TL) of the refrigerant flowing through the third pipe (33) rises.
  • the outdoor controller (101) performs the first control until the refrigerant temperature (TL) of the third pipe (33) detected by the liquid temperature sensor (74) reaches the target temperature (target TL).
  • thermal stress is generated in the supercooling heat exchanger (40) due to the temperature difference of the refrigerant generated before and after switching from the cooling operation (first refrigeration cycle) to the defrost operation (second refrigeration cycle).
  • the outdoor controller (101) sets the target temperature (target TL) to a temperature at which the supercooling heat exchanger (40) can withstand this thermal stress. Specifically, the outdoor controller (101) sets the target temperature (target TL) to the lower temperature of the temperature A and the temperature B.
  • the temperature A is calculated based on the target temperature of the refrigerant discharged from the compression element (20) during the defrost operation.
  • the temperature A is calculated in consideration of the number of defrost operations and the temperature of the liquid refrigerant during the cooling operation.
  • the temperature B is a saturation temperature corresponding to the high pressure during the cooling operation.
  • the outdoor controller (101) sets an upper limit value in the control range of the opening degree of the injection valve (26) in the first control.
  • This upper limit value is the opening degree (Pls1) stored in step ST1. Therefore, the outdoor controller (101) adjusts the opening degree of the injection valve (26) in the range of the upper limit opening degree (Pls1) or less in the first control.
  • step ST4 the outdoor controller (101) performs the second control to increase the opening degree of the injection valve (26) so as to increase the pressure of the refrigerant in the second flow path (40b).
  • the second control raises the evaporation temperature of the refrigerant in the second flow path (40b). Therefore, the cooling capacity of the first flow path (40a) of the second flow path (40b) with respect to the refrigerant is reduced. As a result, the temperature of the refrigerant flowing through the first flow path (40a) rises, and the temperature (TL) of the refrigerant flowing through the third pipe (33) rises.
  • the outdoor controller (101) performs the second control until the pressure (MP) detected by the pressure sensor (77) reaches the target intermediate pressure (target MP).
  • the target intermediate pressure (target MP) is calculated based on the saturation pressure corresponding to the target temperature (target TL) of the refrigerant in the third pipe (33).
  • step ST5 the outdoor controller (101) adjusts the opening degree of the second electric valve (28) so that the second discharge temperature (Td2) approaches a predetermined value. Specifically, the outdoor controller (101) adjusts the amount of refrigerant introduced into the intermediate pressure portion of the first low-stage compressor (22). This predetermined value is, for example, 95 ° C.
  • step ST6 the outdoor controller (101) adjusts the opening degree of the third electric valve (29) so that the third discharge temperature (Td3) approaches a predetermined value. Specifically, the outdoor controller (101) adjusts the amount of refrigerant introduced into the intermediate pressure portion of the second low-stage compressor (23). This predetermined value is, for example, 95 ° C.
  • step ST7 the outdoor controller (101) determines whether or not the temperature (TL) of the refrigerant in the third pipe (33) is higher than the target temperature (target TL).
  • the outdoor controller (101) ends the first operation and proceeds to step ST8. If the temperature (TL) of the refrigerant in the third pipe (33) is equal to or lower than the target temperature (target TL), the process proceeds to step ST2.
  • step ST8 the outdoor controller (101) starts the second refrigeration cycle (defrost operation) from the first refrigeration cycle by switching the four-way switching valve (24) from the first state to the second state.
  • the embodiment includes a heat source circuit (11) including a compression element (20), a heat source heat exchanger (14), a supercooling heat exchanger (40) and a switching mechanism (24), and a utilization heat exchanger (54).
  • It is a heat source unit that constitutes a refrigerant circuit (2) that performs a refrigeration cycle by being connected to the utilization unit (50), and the switching mechanism (24) uses the heat source heat exchanger (14) as a radiator.
  • the supercooling heat exchanger (40) is configured to switch between cycles, and the first flow path (40a) connected in the middle of the liquid pipes (32, 33) through which the liquid refrigerant of the heat source circuit (11) flows. ) And a second flow path (40b) through which a heat medium for cooling the refrigerant flowing through the first flow path (40a) flows, and before switching from the first refrigeration cycle to the second refrigeration cycle.
  • the second flow path (40b) is provided with an adjusting mechanism for performing a first operation of reducing the cooling capacity of the first flow path (40a) with respect to the refrigerant.
  • the cooling capacity of the second flow path (40b) for the refrigerant in the first flow path (40a) is reduced by performing the first operation before switching from the first refrigeration cycle to the second refrigeration cycle. Therefore, the temperature of the refrigerant in the first flow path (40a) rises. This makes it possible to suppress an increase in the thermal stress of the supercooling heat exchanger (40) with respect to the high-temperature refrigerant flowing into the first flow path (40a). As a result, damage to the supercooled heat exchanger (40) can be suppressed.
  • the switching mechanism (24) switches to the second refrigeration cycle when the temperature of the refrigerant flowing through the first flow path (40a) becomes higher than a predetermined value during the first operation.
  • the second refrigeration cycle is started when the temperature of the refrigerant in the first flow path (40a) is higher than a predetermined value.
  • This predetermined value is the target temperature (target TL) of the refrigerant flowing into the third pipe (33) from the first flow path (40a).
  • the target temperature (TL) is the supercooling heat exchanger (40) due to the thermal stress caused by the high temperature refrigerant flowing into the first flow path (40a) from the internal heat exchanger (54) side in the defrost operation (second refrigeration cycle). ) Is the temperature that can be tolerated.
  • the high-temperature refrigerant flows into the first flow path (40a) immediately after the start of the defrost operation (second refrigeration cycle), damage to the supercooling heat exchanger (40) can be reliably suppressed.
  • the heat source circuit (11) has one end branched from the liquid pipe (32, 33) and the other end communicating with the intermediate pressure portion of the compression element (20), and the refrigerant as the heat medium is used. It has an injection circuit (60) including the second flow path (40b) through which it flows, and an expansion valve (26) connected to the upstream side of the second flow path (40b) in the injection circuit (60).
  • the adjusting mechanism (80) includes the expansion valve (26) and a control unit (101) that controls the opening degree of the expansion valve (26) so as to reduce the cooling capacity in the first operation.
  • the outdoor controller (101) controls the opening of the expansion valve (26).
  • the expansion valve (26) regulates the pressure and flow rate of the refrigerant flowing into the second flow path (40b). As a result, the refrigerating capacity of the second flow path (40b) can be reliably reduced.
  • the injection circuit (60) is communicated with the intermediate pressure section of each compressor (21-23). As a result, the refrigerant flowing through the injection circuit (60) can be injected into each compressor (21 to 23).
  • the injection temperature of the refrigerant (Td2 to Td3) of the first and second low-stage compressors (21 to 22) can be lowered by the injected refrigerant.
  • control unit (101) performs the first control in the first operation to reduce the opening degree of the expansion valve (26) so as to reduce the flow rate of the refrigerant in the second flow path (40b). Do.
  • the first control reduces the flow rate of the refrigerant flowing into the second flow path (40b). Therefore, the amount of heat exchanged between the refrigerant in the second flow path (40b) and the refrigerant in the first flow path (40a) can be reduced. As a result, the cooling capacity of the second flow path (40b) can be reliably reduced.
  • control unit (101) increases the opening degree of the expansion valve (26) so as to increase the pressure of the refrigerant in the second flow path (40b) in the first operation. I do.
  • the evaporation temperature of the refrigerant in the second flow path (40b) is increased by the second control. Therefore, the cooling capacity of the first flow path (40a) of the second flow path (40b) with respect to the refrigerant is reduced.
  • the refrigerant is transferred from the injection circuit (60) to the first low-stage compressor (22) and the second low-stage compressor (23). Can be introduced. Thereby, the second discharge temperature (Td2) of the first low-stage compressor (22) and the third discharge temperature (Td3) of the second low-stage compressor (23) can be controlled.
  • the control unit (101) when the condition indicating that the discharge temperature, which is the temperature of the refrigerant discharged from the compression element (20), is low in the first operation, the control unit (101) satisfies the second flow path.
  • the first control for reducing the opening degree of the expansion valve (26) is performed so as to reduce the flow rate of the refrigerant of (40b), and when the condition indicating that the discharge temperature of the compression element (20) is high is satisfied, the first control is performed.
  • the second control is performed to increase the opening degree of the expansion valve (26) so as to increase the pressure of the refrigerant in the two flow paths (40b).
  • the cooling capacity of the second flow path (40b) can be quickly reduced by reducing the opening degree of the injection valve (26) in the first control. Further, the temperature of the refrigerant in the first flow path (40a) can be easily increased without adjusting the discharge temperature (Td2 to Td3) of the first to second lower stage compressors (22 to 23). In the second control, the cooling capacity of the second flow path (40b) can be reduced by increasing the opening degree of the injection valve (26). Since the refrigerant is introduced into the first and second low-stage compressors (22 to 23), the discharge temperature (Td2 to Td3) of the first and second low-stage compressors (22 to 23) is surely lowered. it can.
  • the heat source circuit (11) has a flow rate adjusting valve (28, 29) connected to the downstream side of the second flow path (40b) in the injection circuit (60), and the first operation.
  • the opening degree of the flow rate adjusting valve (28, 29) is adjusted so that the discharge temperature of the refrigerant discharged from the compression element (20) approaches a predetermined value.
  • the opening degrees of the second electric valve (28) and the third electric valve (29), which are flow rate adjusting valves, are adjusted so that the first and second low-stage compressors (22 to 23) can be used.
  • the amount of refrigerant introduced can be adjusted.
  • each discharge temperature (Td2 to Td3) of the first to second lower stage compressors (22 to 23) can be adjusted.
  • the temperature rise of the refrigerant flowing into the high-stage compressor (21) is suppressed, so that the degree of superheat of the discharged refrigerant discharged from the high-stage compressor (21) can be suppressed from becoming excessively high. it can.
  • the overcooling heat exchanger (40) having the first flow path (40a) and the second flow path (40b) and the refrigerant radiated by the utilization heat exchanger (54) in the second refrigeration cycle
  • the bypass flow path (70) configured to bypass the first flow path (40a) at least in part, and in the second refrigeration cycle, the flow of the refrigerant in the first flow path (40a) is restricted and the bypass flow. It has a flow path switching mechanism (180) that allows the flow of refrigerant in the road (70).
  • the flow of the refrigerant through the bypass flow path (70) is restricted. Therefore, during the operation of the first refrigeration cycle, a sufficient amount of the refrigerant flowing through the first flow path (40a) of the supercooling heat exchanger (40) can be secured. Therefore, the cooling capacity of the internal unit (50) can be improved.
  • the compression element (20) has a first compression section (22, 23) and a second compression section (21), and the first compression section (22, 23) in the first refrigeration cycle.
  • This is a two-stage compression type in which the refrigerant compressed in 1 is further compressed by the second compression unit (21).
  • the evaporation pressure in the first refrigeration cycle is lower than that in the single-stage compression type. Therefore, in the first refrigeration cycle, the refrigerant is cooled to a relatively low temperature (for example, ⁇ 35 ° C.) in the first flow path (40a).
  • a relatively low temperature for example, ⁇ 35 ° C.
  • the relatively high temperature refrigerant radiated by the internal heat exchanger (54) flows into the heat source circuit (11). Therefore, in the two-stage compression type, the problem that the thermal stress of the supercooling heat exchanger (40) increases due to such a temperature difference becomes remarkable.
  • the heat source circuit (11) includes the adjusting mechanism (80)
  • the refrigerating capacity of the second flow path (40b) can be reduced by the first operation. Therefore, in the outdoor unit (10) provided with a two-stage compression type compression element, an increase in thermal stress in the first flow path (40a) due to switching from the first refrigeration cycle to the second refrigeration cycle can be suppressed.
  • the first modification is a modification of a part of the configuration of the heat source unit (10) of the embodiment.
  • the first modification is a modification of a part of the configuration of the heat source unit (10) of the embodiment.
  • a part different from the embodiment will be described.
  • one end of the relay pipe (62) is connected to the outflow end of the second flow path (40b).
  • the other end of the relay pipe (62) communicates with the suction portion of the first low-stage compressor (22) and the suction portion of the second low-stage compressor.
  • one end of the relay pipe (62) is connected to one end of the second flow path (40b), and the other end is connected in the middle of the first confluence pipe (48).
  • the relay pipe (62) is provided with a fourth electric valve (68).
  • the fourth electric valve (68) is a flow rate adjusting valve that adjusts the flow rate of the refrigerant introduced into the first low-stage compressor (22) and the second low-stage compressor (23).
  • One end of the first injection pipe (63) is connected to the intermediate pressure part of the high-stage compressor (21).
  • the other end of the first injection pipe (63) is connected to one end of the second injection pipe (64) and one end of the third injection pipe (65).
  • the other end of the second injection pipe (64) and the other end of the third injection pipe (65) are the intermediate pressure portion of the first low-stage compressor (22) and the other end of the second low-stage compressor (23), respectively. Connect to the intermediate pressure section.
  • the injection circuit is equipped with a second branch pipe (66).
  • One end of the second branch pipe (66) is connected between the connection portion of the first branch pipe (61) with the third pipe (33) and the injection valve (26).
  • the other end of the second branch pipe (66) is between the connection portion of the second injection pipe (64) and the third injection pipe (65) in the first injection pipe (63) and the first electric valve (27). Connect to.
  • the refrigerant from the outdoor heat exchanger (14) side passes through the first flow path (40a) and flows into the third pipe (33) as in the above embodiment.
  • a part of the refrigerant in the third pipe (33) flows into the first branch pipe (61).
  • the rest of the refrigerant in the third pipe (33) flows to the internal heat exchanger (54) side.
  • the refrigerant in the second branch pipe (66) is diverted to the first to third injection pipes (63 to 65).
  • the flow rates of the refrigerants in the first to third injection pipes (63 to 65) are appropriately adjusted by the first to third electric valves (27 to 29), and the intermediate pressure portion of each compressor (21 to 23) is adjusted. Introduced in.
  • the rest of the refrigerant in the first branch pipe (61) is decompressed by the injection valve (26) and flows into the second flow path (40b).
  • the refrigerant in the first flow path (40a) is cooled by heat exchange between the refrigerant in the second flow path (40b) and the refrigerant in the first flow path (40a).
  • the refrigerant that has passed through the second flow path (40b) flows in the order of the relay pipe (62) and the first confluence pipe (48). This refrigerant splits into the second suction pipe (45) and the third suction pipe (46). The diverted refrigerant is introduced into the suction section of the first low-stage compressor (22) and the suction section of the second low-stage compressor (23).
  • the outdoor controller (101) controls the injection valve (26) and the fourth electric valve (68).
  • step ST11 when a command to execute the first operation is input to the outdoor controller (101), in step ST11, the second discharge temperature sensor (72) and the third discharge temperature sensor (73) are set to the third. 1 Detects the discharge temperature (Td2, Td3) of the low-stage compressor (22) and the second low-stage compressor (23).
  • the outdoor controller (101) has a second discharge temperature (Td2) of the first low-stage compressor (22) and a third discharge temperature (Td3) of the second low-stage compressor (23). It is determined whether or not the condition indicating that both are high is satisfied. More specifically, the outdoor controller (101) determines whether or not the following conditions a) and b) are satisfied.
  • the second discharge temperature (Td2) of the first low-stage compressor (22) is lower than the predetermined value.
  • This predetermined value is, for example, 95 ° C.
  • the third discharge temperature (Td3) of the second lower stage compressor (23) is lower than the predetermined value.
  • This predetermined value is, for example, 95 ° C.
  • step ST11 If both the above conditions a) and b) are satisfied in step ST11, the process proceeds to step ST12. If at least one of the above conditions a) and b) is not satisfied in step ST11, the process proceeds to step ST13.
  • step ST12 the outdoor controller (101) performs the first control to fully close the injection valve (26).
  • the refrigerant does not flow into the second flow path (40b). Therefore, the cooling capacity of the first flow path (40a) of the second flow path (40b) with respect to the refrigerant is reduced. As a result, the temperature of the refrigerant in the first flow path (40a) rises.
  • step ST13 the outdoor controller (101) performs the second control to fully open the injection valve (26).
  • the refrigerant flowing into the first branch pipe (61) flows into the second flow path (40b) without being depressurized by the injection valve (26). Therefore, the cooling capacity of the first flow path (40a) of the second flow path (40b) with respect to the refrigerant is reduced. As a result, the temperature of the refrigerant in the first flow path (40a) rises.
  • step ST14 the outdoor controller (101) adjusts the opening degree of the fourth electric valve (68) so that the second discharge temperature (Td2) and the third discharge temperature (Td3) become the target discharge temperature.
  • the refrigerant that has passed through the second flow path (40b) passes through the relay pipe (62) and is divided into the second suction pipe (45) and the third suction pipe (46).
  • the separated refrigerant is introduced into each suction portion of the first low-stage compressor (22) and the second low-stage compressor (23), respectively.
  • the outdoor controller (101) controls the fourth electric valve (68) of the relay pipe (62) and is introduced into the first low-stage compressor (22) and the second low-stage compressor (23). Adjust the flow rate of the refrigerant.
  • the second discharge temperature (Td2) and the third discharge temperature (Td3) are adjusted to be the target discharge temperatures.
  • the target discharge temperature is, for example, 95 ° C.
  • step ST15 the outdoor controller (101) determines whether or not the temperature (TL) of the refrigerant in the third pipe (33) is higher than the target temperature (target TL).
  • the outdoor controller (101) ends the first operation and shifts to ST16. If the temperature (TL) of the refrigerant in the third pipe (33) is equal to or lower than the target temperature (target TL), the process proceeds to step ST11.
  • step ST16 the outdoor controller (101) switches the four-way switching valve (24) from the first state to the second state, and starts the second refrigeration cycle (defrost operation) from the first refrigeration cycle.
  • the injection valve (26) is fully opened in the first control, and the injection valve (26) is fully closed in the second control.
  • the cooling capacity of the second flow path (40b) for the refrigerant of the first flow path (40a) can be reliably reduced.
  • the first control it is only necessary to fully close the injection valve (26).
  • the second control it is only necessary to fully open the injection valve (26).
  • the first operation can be easily controlled.
  • the refrigerant flowing through the injection circuit (60) is introduced into the suction section of the first low-stage compressor (22) and the second low-stage compressor (23).
  • the discharge temperatures (Td2 to Td3) of the first low-stage compressor (22) and the second low-stage compressor (23) can be lowered.
  • the second modification is a modification of a part of the configuration of the heat source unit (10) of the embodiment. Hereinafter, a part different from the embodiment will be described.
  • the injection circuit (60) includes a third branch pipe (67).
  • One end of the third branch pipe (67) is connected between the connection portion of the first branch pipe (61) with the third pipe (33) and the injection valve (26).
  • the outflow portion of the third branch pipe (67) is connected to each inflow end of the first to third injection pipes (63 to 65).
  • the third branch pipe (67) is provided with a fifth electric valve (69).
  • the fifth electric valve (69) is a flow rate adjusting valve that controls the flow rate of the refrigerant in the third branch pipe (67).
  • the refrigerant from the outdoor heat exchanger (14) side passes through the first flow path (40a) and flows into the third pipe (33) as in the above embodiment.
  • a part of the refrigerant in the third pipe (33) flows into the first branch pipe (61).
  • the rest of the refrigerant in the third pipe (33) flows to the internal heat exchanger (54) side.
  • the refrigerant in the third branch pipe (67) is diverted to the first to third injection pipes (63 to 65).
  • the flow rates of the refrigerants in the first to third injection pipes (63 to 65) are appropriately adjusted by the first to third electric valves (27 to 29), and the intermediate pressure portion of each compressor (21 to 23) is adjusted. Introduced in.
  • the rest of the refrigerant in the first branch pipe (61) is decompressed by the injection valve (26) and flows into the second flow path (40b).
  • the refrigerant in the first flow path (40a) is cooled by heat exchange between the refrigerant in the second flow path (40b) and the refrigerant in the first flow path (40a).
  • the refrigerant that has passed through the second flow path (40b) flows in the order of the relay pipe (62) and the first confluence pipe (48). This refrigerant splits into the second suction pipe (45) and the third suction pipe (46). The diverted refrigerant is introduced into the suction section of the first low-stage compressor (22) and the suction section of the second low-stage compressor (23).
  • the controller (100) controls the injection valve (26) and the fifth electric valve (69).
  • the controller (100) fully closes the injection valve (26). Therefore, the refrigerant does not flow into the second flow path (40b). As a result, the cooling capacity of the second flow path (40b) for the refrigerant in the first flow path (40a) is reduced.
  • the temperature of the refrigerant in the first flow path (40a) rises.
  • the first operation is terminated and the defrost operation is executed.
  • the target temperature referred to here is the same as the target temperature in the above embodiment.
  • the amount of refrigerant introduced into the first to second lower stage compressors (21 to 22) is adjusted so that the second to third discharge temperatures become the target discharge temperatures, respectively.
  • the flow rate of the refrigerant flowing through the third branch pipe (67) is adjusted by the fifth electric valve (69).
  • This refrigerant is divided into a second injection pipe (64) and a third injection pipe (65).
  • the flow rate of the refrigerant is adjusted by the second electric valve (28) and the third electric valve (29).
  • This refrigerant is introduced into the intermediate pressure portion of the first to second lower stage compressors (21 to 22).
  • the cooling capacity of the second flow path (40b) for the refrigerant of the first flow path (40a) can be reduced by the first operation.
  • an increase in thermal stress of the supercooled heat exchanger (40) can be suppressed.
  • the injection valve (26) is fully closed in the first operation regardless of the discharge temperature (Td2 to Td3) of the first to second lower stage compressors (22 to 23), and the fifth electric motor is used.
  • the flow rate of the refrigerant introduced into the first to second lower stage compressors (21 to 22) may be adjusted by the valve (69).
  • the first operation can be easily controlled.
  • Modification 3 is a modification of a part of the configuration of the outdoor unit (10) of the embodiment. Hereinafter, a part different from the embodiment will be described.
  • the heat source circuit (11) of the third modification includes a sixth tube (36).
  • the sixth pipe (36) is a bypass flow path (70) that bypasses the first flow path (40a).
  • the sixth pipe (36) is connected to the liquid pipes (32, 33) in parallel with the supercooling heat exchanger (40). Specifically, one end of the sixth pipe (36) is connected to the second pipe (32). The other end of the sixth pipe (36) is connected to the downstream side of the fifth outdoor check valve (CV5) in the third pipe (33).
  • the eighth outdoor check valve (CV9) is connected to the sixth pipe (36).
  • the eighth outdoor check valve (CV9) allows the flow of refrigerant from the internal heat exchanger (54) side to the outdoor heat exchanger (14) side in the second refrigeration cycle, and prohibits the reverse flow. ..
  • the flow path switching mechanism (180) has an eighth outdoor check valve (CV9) and a fifth outdoor check valve (CV5).
  • the fifth outdoor check valve (CV5) has a connection portion of the sixth pipe (36) in the third pipe (33) and an end portion of the first flow path (40a) on the internal heat exchanger (54) side. Is connected between.
  • the fifth outdoor check valve (CV5) allows the flow of refrigerant from the outdoor heat exchanger (14) side to the internal heat exchanger (54) side, and prohibits the reverse flow of refrigerant.
  • the inflow end of the first branch pipe (61) of the injection circuit (60) is connected between the connection portion of the sixth pipe (36) in the third pipe (33) and the liquid side closing valve (17).
  • the first to third injection pipes (63 to 65) are connected to the outflow portion of the first branch pipe (61), respectively.
  • One end of the 4th pipe (34) is connected between the connection part of the 6th pipe (36) in the 2nd pipe (32) and the connection part of the 5th pipe (35).
  • the other end of the fourth pipe (34) is connected to the downstream side of the fourth outdoor check valve (CV4) in the first pipe (31).
  • the refrigerant compressed by the low-stage compressors (22, 23) and further compressed by the high-stage compressor (21) is dissipated to the outdoor air by the outdoor heat exchanger (14).
  • the refrigerant dissipated by the outdoor heat exchanger (14) flows through the first pipe (31). After flowing into the liquid receiver (39), this refrigerant flows through the second pipe (32) toward the supercooling heat exchanger (40).
  • the refrigerant in the second pipe (32) circulates in the first flow path (40a) of the supercooled heat exchanger (40).
  • the eighth outdoor check valve (CV9) prohibits the inflow of the refrigerant into the sixth pipe (36), which is the bypass flow path (70).
  • the refrigerant flowing through the first flow path (40a) is heat-exchanged by the refrigerant flowing through the second flow path (40b) to be cooled.
  • a part of the refrigerant flowing into the third pipe (33) flows into the first branch pipe (61), and the rest flows toward the internal heat exchanger (54).
  • the refrigerant flowing into the first branch pipe (61) is introduced from each injection pipe (63 to 65) into the compression chamber of each compressor (21 to 23).
  • the refrigerant flowing toward the internal unit (50) flows through the liquid communication pipe (3) and is sent to the internal unit (50).
  • the refrigerant that has passed through the liquid communication pipe (3) from the internal unit (50) flows into the third pipe (33).
  • the refrigerant in the third pipe (33) does not flow into the first flow path (40a) by the fifth outdoor check valve (CV5), but passes through the sixth pipe (36) which is the bypass flow path (70). ..
  • the refrigerant that has flowed through the sixth pipe (36) flows in the order of the second pipe (32), the fourth pipe (34), the first pipe (31), the receiver (39), and the second pipe (32).
  • the refrigerant is depressurized by the outdoor expansion valve (25), passes through the fifth pipe (35) and the first pipe (31), and flows into the outdoor heat exchanger (14).
  • the refrigerant that has flowed into the second pipe (32) from the sixth pipe (36) does not flow through the first flow path (40a). This is because the differential pressure before and after the fifth outdoor check valve (CV5) prohibits the flow of the refrigerant in the fifth outdoor check valve (CV5). Similarly, the refrigerant flowing into the first pipe (31) does not flow to the receiver (39) side due to the differential pressure before and after the fourth outdoor check valve (CV4).
  • the fifth outdoor check valve (CV5) and the eighth outdoor check valve (CV9) prohibit the flow of the refrigerant in the first flow path (40a) in the second refrigeration cycle, and bypass the flow. Allows the flow of refrigerant in the flow path (70). Therefore, in the second refrigeration cycle, the refrigerant flowing from the internal unit (50) flows through the sixth pipe (36), which is the bypass flow path (70), and surely flows through the first flow path (40a). Can be suppressed. As a result, even in the first modification, it is possible to prevent the relatively high temperature refrigerant from flowing into the first flow path (40a) immediately after switching from the first refrigeration cycle to the second refrigeration cycle. Therefore, an increase in thermal stress of the supercooled heat exchanger (40) can be suppressed.
  • the flow path of the refrigerant can be automatically switched when switching between the first refrigeration cycle and the second refrigeration cycle. Therefore, also in the first modification, the increase in thermal stress of the supercooled heat exchanger (40) can be reliably suppressed immediately after switching from the first refrigeration cycle to the second refrigeration cycle.
  • the flow path switching mechanism (180) of the second modification is composed of a first three-way switching valve (81) and a second three-way switching valve (82).
  • the first three-way switching valve (81) is connected to the connection portion between the second pipe (32) and the sixth pipe (36). Specifically, the third port (P3) of the first three-way switching valve (81) is connected to the second pipe (32) extending from the outdoor heat exchanger (14) side. The second port (P2) is connected to one end of the sixth pipe (36). The first port (P1) is connected to the second pipe (32) extending from the first flow path (40a) side.
  • the second three-way switching valve (82) is connected to the connection between the third pipe (33) and the sixth pipe (36). Specifically, the first port (P1) of the second three-way switching valve (82) is connected to the third pipe (33) extending from the internal heat exchanger (54) side. The second port (P2) is connected to the other end of the sixth pipe (36). The third port (P3) is connected to the third pipe (33) extending from the first flow path (40a) side.
  • the flow path switching mechanism (180) is controlled by the controller (100).
  • the first state the state shown by the solid line in FIG. 12
  • the first three-way switching valve (81) and the second three-way switching valve (82) have the first port (P1) and the third port (P3), respectively. Connecting.
  • the second state the state shown by the broken line in FIG. 12
  • the first three-way switching valve (P1) and the second three-way switching valve (P2) are the first port (P1) and the second port (P2), respectively. Connect to each other.
  • the flow path switching mechanism (180) is in the first state.
  • the refrigerant does not flow into the sixth pipe (36), which is the bypass flow path (70), but flows through the first flow path (40a).
  • the inflow of the refrigerant into the bypass flow path (70) is prohibited, so that the entire amount of the refrigerant can flow through the first flow path (40a).
  • the flow path switching mechanism (180) is in the second state.
  • the refrigerant does not flow into the first flow path (40a) but flows through the sixth pipe (36), which is the bypass flow path (70).
  • the inflow of the refrigerant into the first flow path (40a) is prohibited, so that the entire amount of the refrigerant can flow through the bypass flow path (70).
  • the refrigerant flowing in from the internal heat exchanger (54) side bypasses the first flow path (40a).
  • the refrigerant flowing in from the internal heat exchanger (54) side bypasses the first flow path (40a).
  • the outdoor unit (10) of the modified example 5 includes a supercooling unit (90).
  • the supercooling unit (90) includes a supercooling circuit (91) and a supercooling fan (94).
  • the supercooling circuit (91) includes a compressor for supercooling (92), a heat exchanger for supercooling (93), an expansion valve for supercooling (26), and a second flow path (40b).
  • the supercooling circuit (91) is a refrigerant circuit independent of the heat source circuit (11).
  • the refrigerant as a heat medium is a compressor for supercooling (92), a heat exchanger for supercooling (93), an expansion valve for supercooling (26), and a second flow path (40b). ) Is configured to flow in this order.
  • the supercooling compressor (92) consists of a fully enclosed high-pressure dome-shaped scroll compressor.
  • a compressor unit (not shown) and an electric motor (not shown) for driving the compressor unit are connected to the supercooling compressor (92), respectively.
  • An inverter that can freely change the rotation speed of the electric motor within a predetermined range is connected to the electric motor of the supercooling compressor (92). With this inverter, the rotation speed of the electric motor can be adjusted to increase or decrease the operating capacity of the supercooling compressor (92).
  • the supercooling heat exchanger (93) is a fin-and-tube type air heat exchanger.
  • the supercooling fan (94) is arranged in the vicinity of the supercooling heat exchanger (93).
  • the supercooling fan (94) conveys outdoor air.
  • the supercooling heat exchanger (93) exchanges heat between the high-pressure refrigerant flowing inside the supercooling heat exchanger (93) and the outdoor air carried by the supercooling fan (94).
  • the supercooling expansion valve (26) is an electronic expansion valve whose opening is variable. By adjusting the opening degree of the supercooling expansion valve (26), the temperature of the refrigerant flowing through the second flow path (40b) is adjusted.
  • a low-pressure refrigerant flows through the second flow path (40b) due to the supercooling expansion valve (26).
  • the refrigerant flowing through the second flow path (40b) absorbs heat from the refrigerant flowing through the first flow path (40a) and evaporates.
  • the supercooling unit (90) operates a supercooling compressor (92) and a supercooling fan (94).
  • the opening degree of the supercooling expansion valve (26) is adjusted as appropriate.
  • the refrigerant compressed by the supercooling compressor (92) dissipates heat to the outdoor air in the supercooling heat exchanger (93).
  • the heat-dissipated refrigerant is decompressed by the supercooling expansion valve (26) and then flows into the second flow path (40b).
  • the refrigerant in the second flow path (40b) exchanges heat with the refrigerant flowing in the first flow path (40a), and then is sucked into the supercooling compressor (92) again.
  • the refrigerant compressed in the low-stage compressors (22, 23) and the high-stage compressor (21) is outdoors in the outdoor heat exchanger (14). Dissipate heat to the air.
  • the heat-dissipated refrigerant flows through the first pipe (31). After flowing into the liquid receiver (39), this refrigerant flows through the second pipe (32) and flows through the first flow path (40a) of the supercooled heat exchanger (40).
  • the refrigerant flowing through the first flow path (40a) is heat-exchanged by the refrigerant flowing through the second flow path (40b) to be cooled.
  • a part of the refrigerant flowing into the third pipe (33) flows into the first branch pipe (61), and the rest flows toward the internal heat exchanger (54).
  • the refrigerant that has passed through the liquid communication pipe (3) from the internal unit (50) flows into the third pipe (33).
  • the refrigerant in the third pipe (33) does not flow into the first flow path (40a) by the fifth outdoor check valve (CV5), but passes through the sixth pipe (36) which is the bypass flow path (70). ..
  • the refrigerant that has flowed through the sixth pipe (36) flows in the order of the second pipe (32), the fourth pipe (34), the first pipe (31), the receiver (39), and the second pipe (32).
  • the refrigerant is depressurized by the outdoor expansion valve (25), passes through the fifth pipe (35) and the first pipe (31), and flows into the outdoor heat exchanger (14).
  • the refrigerant flowing from the 6th pipe (36) to the 2nd pipe (32) does not flow through the 1st flow path (40a) due to the differential pressure before and after the 5th outdoor check valve (CV5).
  • the refrigerant flowing from the 5th pipe (35) to the 1st pipe (31) does not flow to the receiver (39) due to the differential pressure before and after the 4th outdoor check valve (CV4).
  • the refrigerant flowing in from the internal heat exchanger (54) side bypasses the first flow path (40a).
  • the refrigerant flowing in from the internal heat exchanger (54) side bypasses the first flow path (40a).
  • the supercooling unit (90) has a supercooling circuit (91) which is a refrigerant circuit independent of the heat source circuit (11). Therefore, the temperature of the refrigerant flowing through the second flow path (40b) can be controlled independently.
  • the above embodiment may have the following configuration.
  • the second refrigeration cycle may be a heating operation in which the internal heat exchanger (54) is used as a radiator and the outdoor heat exchanger (14) is used as an evaporator.
  • the controller (100) receives an instruction to perform the heating operation during the cooling operation, the refrigerating device (1) performs the first operation.
  • the temperature of the refrigerant in the first flow path (40a) reaches the target temperature (target TL)
  • the heating operation is started.
  • the refrigerant flowing from the internal heat exchanger (54) side to the outdoor heat exchanger (14) side bypasses the first flow path (40a). Even in this case, the increase in thermal stress of the supercooled heat exchanger (40) can be suppressed.
  • the compression element (20) may be a single-stage compression type.
  • the high-stage compressor (21) in the first refrigeration cycle (cooling operation), the high-stage compressor (21) is operated, and the first low-stage compressor (22) and the second low-stage compressor (23) are operated. ) Is stopped.
  • the sixth electric valve (53) is fully opened.
  • the refrigerant that has flowed into the first confluence pipe (48) from the internal heat exchanger (54) side flows through the connection pipe (49) and is sucked into the high-stage compressor (21).
  • the refrigerant compressed by the high-stage compressor (21) flows through the outdoor heat exchanger (14), the liquid receiver (39), and the supercooled heat exchanger (40) as in the above embodiment. In this way, the refrigerant flows through the refrigerant circuit (2).
  • the compression element (20) may be a single-stage compression type in which a plurality of compressors are connected in parallel.
  • the first control in the first operation may be a control for fully closing the opening degree of the injection valve (26).
  • the cooling capacity of the second flow path (40b) for the refrigerant in the first flow path (40a) can be reduced.
  • the second control in the second operation, may be a control for fully opening the opening degree of the injection valve (26).
  • the cooling capacity of the second flow path (40b) for the refrigerant in the first flow path (40a) can be reduced.
  • the value of the temperature (Tg1) of the refrigerant flowing into the second flow path (40b) may be the saturated liquid temperature conversion value of the pressure sensor (77) instead of the first temperature sensor (75). Good. Further, as the value of the pressure (MP) of the refrigerant in the relay pipe (62), the saturated liquid pressure conversion value of the first temperature sensor (75) may be used instead of the pressure sensor (77).
  • the heat source unit (10) does not have to have a bypass flow path (70). Similarly, the heat source unit (10) does not have to have a flow path switching mechanism (180).
  • the utilization circuit (51) does not have to include the internal bypass flow path (58).
  • the internal expansion valve (30) is an electronic expansion valve whose opening degree can be adjusted. In the operation in which the internal heat exchanger (54) functions as a radiator, the internal expansion valve (30) is fully opened.
  • the flow path switching mechanism (180) may be an electric valve whose opening degree can be adjusted.
  • the 5th outdoor check valve (CV5) and the 6th outdoor check valve (CV6) of the above embodiment, and the 5th outdoor check valve (CV5) and the 8th outdoor check valve of the above modification 3 (CV9) may be an electric valve.
  • the flow rate of the refrigerant in the first flow path (40a) and the flow rate of the refrigerant in the bypass flow path (70) can be adjusted by adjusting the opening degree of each electric valve. This allows at least a portion of the refrigerant to flow through the bypass flow path (70) in the second refrigeration cycle.
  • the increase in thermal stress of the supercooling heat exchanger (40) can be suppressed by adjusting the flow rate of the refrigerant flowing through the bypass flow path (70). Further, in the first refrigeration cycle, at least a part of the refrigerant can be adjusted so that it can flow through the bypass flow path (70). This makes it possible to adjust the amount of refrigerant heat exchanged in the first flow path (40a) in the first refrigeration cycle.
  • the flow path switching mechanism (180) may be an on-off valve that only opens and closes.
  • the 5th outdoor check valve (CV5) and the 6th outdoor check valve (CV6) of the above embodiment, and the 5th outdoor check valve (CV5) and the 8th outdoor check valve of the above modification 3 (CV9) may be an on-off valve that only opens and closes.
  • one valve is opened so that the refrigerant flows through the first flow path (40a), and the other valve is closed so that the refrigerant does not flow through the bypass flow path (70).
  • the total amount of the refrigerant can flow through the first flow path (40a).
  • one valve is closed so that the refrigerant does not flow through the first flow path (40a), and the other valve is opened so that the refrigerant flows through the bypass flow path (70).
  • the entire amount of the refrigerant can flow through the bypass flow path (70).
  • the flow path switching mechanism (180) may include a first three-way switching valve (81) and a fifth outdoor check valve (CV5). ..
  • the first port (P1) and the third port (P3) of the first three-way switching valve (81) are connected.
  • the inflow of the refrigerant into the sixth pipe (36) is prohibited. Therefore, in the first refrigeration cycle, the entire amount of the refrigerant can flow through the first flow path (40a).
  • the first port (P1) and the second port (P2) of the first three-way switching valve (81) are connected.
  • the inflow of the refrigerant into the first flow path (40a) is prohibited. Therefore, in the second refrigeration cycle, the total amount of the refrigerant can flow through the sixth pipe (36).
  • the flow path switching mechanism (180) may include a second three-way switching valve (82) and an eighth outdoor check valve (CV9). ..
  • the first port (P1) and the third port (P3) of the second three-way switching valve (82) are connected.
  • the inflow of the refrigerant into the sixth pipe (36) is prohibited. Therefore, in the first refrigeration cycle, the entire amount of the refrigerant can flow through the first flow path (40a).
  • the first port (P1) and the second port (P2) of the second three-way switching valve (82) are connected.
  • the inflow of the refrigerant into the first flow path (40a) is prohibited. Therefore, in the second refrigeration cycle, the total amount of the refrigerant can flow through the sixth pipe (36).
  • the flow path switching mechanism (180) may include only the second three-way switching valve (82). In the first refrigeration cycle, the first port (P1) and the third port (P3) of the second three-way switching valve (82) are connected. In the second refrigeration cycle, the first port (P1) and the second port (P2) of the second three-way switching valve (82) are connected.
  • the injection circuit (60) is not limited to the above embodiment.
  • the injection circuit (60) may be appropriately modified as long as the functions disclosed in the above embodiment are not impaired.
  • the utilization circuit (51) does not have to include the internal bypass flow path (58).
  • the internal expansion valve (30) is an electronic expansion valve whose opening degree can be adjusted. In the operation in which the internal heat exchanger (54) functions as a radiator, the internal expansion valve (30) is fully opened.
  • the outdoor expansion valve (25) may be connected between the connecting end of the receiver (39) and the fifth pipe (35) in the second pipe (32).
  • the present disclosure is useful for heat source units and refrigeration equipment.
  • Refrigerant device Refrigerant circuit 10 Outdoor unit (heat source unit) 11 Heat source circuit 14 Outdoor heat exchanger (heat source heat exchanger) 20 Compression element 21 High-stage compressor (second compression section) 22 First low-stage compressor (first compression unit) 23 Second low-stage compressor (first compression unit) 24 Four-way switching valve (switching mechanism) 26 Injection valve (expansion valve) 28 Second electric valve (flow control valve) 29 Third electric valve (flow control valve) 32 Second pipe (liquid pipe) 33 Third pipe (liquid pipe) 40 Supercooling heat exchanger 40a 1st flow path 40b 2nd flow path 50 Internal unit (utilization unit) 54 Internal heat exchanger (utilized heat exchanger) 60 Injection circuit 70 Bypass flow path 80 Adjustment mechanism 101 Outdoor controller (control unit) 180 Flow path switching mechanism

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)

Abstract

L'invention concerne une unité de source de chaleur (10) qui comprend un circuit de source de chaleur (11) et qui est connectée à une unité d'utilisation (50), constituant ainsi un circuit de réfrigération (2) qui accomplit des cycles de réfrigération. L'unité de source de chaleur (10) comprend : un mécanisme de commutation (24), qui commute entre un premier cycle de réfrigération et un deuxième cycle de réfrigération ; et un échangeur de chaleur de sous-refroidissement (40) qui possède un premier trajet d'écoulement (40a) et un deuxième trajet d'écoulement (40b) à travers lequel s'écoule un fluide de transfert de chaleur qui refroidit un fluide frigorigène qui s'écoule à travers le premier trajet d'écoulement (40a). De plus, l'unité de source de chaleur (10) comprend un mécanisme de réglage (80) qui effectue une première opération qui réduit la capacité du deuxième trajet d'écoulement (40b) en vue de refroidir le fluide frigorigène dans le premier trajet d'écoulement (40a), avant la commutation du premier cycle de réfrigération au deuxième cycle de réfrigération.
PCT/JP2020/027906 2019-09-30 2020-07-17 Unité de source de chaleur et dispositif de réfrigération WO2021065156A1 (fr)

Priority Applications (2)

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CN202080061329.2A CN114341569B (zh) 2019-09-30 2020-07-17 热源机组及制冷装置
EP20871109.3A EP4033178B1 (fr) 2019-09-30 2020-07-17 Dispositif de réfrigération

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JP2019180679A JP6849037B1 (ja) 2019-09-30 2019-09-30 熱源ユニット、冷凍等装置、及び過冷却ユニット
JP2019-180679 2019-09-30
JP2019180683A JP6787465B1 (ja) 2019-09-30 2019-09-30 熱源ユニット及び冷凍装置
JP2019-180683 2019-09-30

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JP2015048983A (ja) 2013-09-02 2015-03-16 株式会社マック 過冷却器及びその過冷却器を組み込んだ蒸気圧縮式冷凍サイクル
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WO2024023988A1 (fr) * 2022-07-27 2024-02-01 三菱電機株式会社 Dispositif à cycle frigorifique

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EP4033178A4 (fr) 2022-10-26
CN114341569B (zh) 2023-04-28
EP4033178B1 (fr) 2024-05-29
EP4033178A1 (fr) 2022-07-27

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