WO2016174822A1 - 冷凍装置 - Google Patents

冷凍装置 Download PDF

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Publication number
WO2016174822A1
WO2016174822A1 PCT/JP2016/001846 JP2016001846W WO2016174822A1 WO 2016174822 A1 WO2016174822 A1 WO 2016174822A1 JP 2016001846 W JP2016001846 W JP 2016001846W WO 2016174822 A1 WO2016174822 A1 WO 2016174822A1
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WO
WIPO (PCT)
Prior art keywords
refrigerant
pipe
expansion valve
heat exchanger
supercooling
Prior art date
Application number
PCT/JP2016/001846
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
竹上　雅章
東 近藤
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
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 ES16786103T priority Critical patent/ES2879920T3/es
Priority to EP16786103.8A priority patent/EP3290825B1/de
Publication of WO2016174822A1 publication Critical patent/WO2016174822A1/ja

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • 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
    • F25B31/00—Compressor arrangements
    • F25B31/002—Lubrication
    • F25B31/004—Lubrication oil recirculating 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
    • F25B40/00—Subcoolers, desuperheaters or superheaters
    • F25B40/02—Subcoolers
    • 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
    • F25B2500/00—Problems to be solved
    • F25B2500/31—Low ambient temperatures
    • 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
    • F25B2700/2101—Temperatures in a bypass
    • 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

Definitions

  • This disclosure relates to refrigeration equipment.
  • Patent Literature 1 discloses a refrigeration apparatus including a refrigerant circuit in which a refrigerant is circulated and a refrigeration cycle is performed.
  • the refrigerant circuit includes a compressor, a heat source side heat exchanger, an expansion valve, and a use side heat exchanger.
  • the use side heat exchanger is provided in the freezer.
  • cooling operation is performed. In the cooling operation, the refrigerant in the use side heat exchanger absorbs heat from the internal air and evaporates, whereby the air in the freezer is cooled.
  • the refrigerant circuit is provided with a supercooling heat exchanger and a supercooling expansion valve.
  • a liquid refrigerant pipe in which the liquid end of the heat source side heat exchanger and the liquid end of the use side heat exchanger are connected to the refrigerant circuit, a middle part of the liquid refrigerant pipe, and the middle of the compressor.
  • An injection pipe connecting the port is provided.
  • the supercooling heat exchanger is connected to the liquid refrigerant pipe and the injection pipe, and is configured to exchange heat between the refrigerant flowing through the liquid refrigerant pipe and the refrigerant flowing through the injection pipe.
  • the supercooling expansion valve is provided between the midway part of the liquid refrigerant pipe and the supercooling heat exchanger in the injection pipe.
  • the refrigerant (high-pressure refrigerant) flowing into the supercooling heat exchanger from the heat source side heat exchanger via the liquid refrigerant piping passes from the supercooling expansion valve via the injection piping. Then, the refrigerant (intermediate pressure refrigerant) flowing into the supercooling heat exchanger absorbs heat and is supercooled, so that the cooling capacity of the use side heat exchanger can be improved.
  • the refrigerant intermediate pressure refrigerant
  • the refrigerant temperature in the compressor (specifically, the temperature in the compression chamber of the intermediate pressure) )
  • the refrigerant discharge refrigerant temperature To lower the refrigerant discharge refrigerant temperature.
  • the pressure of the refrigerant (intermediate pressure refrigerant) flowing into the supercooling heat exchanger from the supercooling expansion valve in the injection pipe decreases, and the refrigerant in the supercooling heat exchanger (intermediate pressure refrigerant)
  • the temperature of the refrigerant from the supercooling heat exchanger to the intermediate port of the compressor in the injection pipe may decrease, and the injection pipe may freeze.
  • buckling occurs in the injection pipe due to ice adhering to the injection pipe, or the ice adhering to the injection pipe comes into contact with other components of the refrigeration apparatus (for example, a casing). May cause vibration and noise.
  • an object of this disclosure is to provide a refrigeration apparatus capable of suppressing freezing of the injection piping while protecting the compressor from high temperature abnormality.
  • the first aspect of the present disclosure includes a compressor (31a, 31b, 31c), a heat source side heat exchanger (33), a use side heat exchanger (61), and the heat source side heat exchanger (33).
  • An injection pipe (54) connecting the intermediate port of 31c), a refrigerant flowing through the liquid refrigerant pipe (50) connected to the liquid refrigerant pipe (50) and the injection pipe (54), and the injection pipe ( 54) a supercooling heat exchanger (34) for exchanging heat with the refrigerant flowing in the refrigerant, and a middle part (P1) of the liquid refrigerant pipe (50) in the injection pipe (54) and the supercooling heat exchanger (34).
  • the refrigerant circuit (20) having intermediate expansion valves (36a, 36b, 36c) provided between the intermediate port and the heat source side heat exchanger (33) in the refrigerant circuit (20) serves as a condenser.
  • the refrigerant flowing into the intermediate port of the compressor (31a, 31b, 31c) is adjusted by adjusting the opening of the intermediate expansion valve (36a, 36b, 36c) in the first opening adjustment operation.
  • the flow rate (injection amount) can be adjusted, and as a result, the temperature drop amount of the refrigerant in the compressor (31a, 31b, 31c) can be adjusted.
  • coolant discharged from a compressor (31a, 31b, 31c) can be adjusted.
  • the supercooling expansion valve (35) flows into the supercooling heat exchanger (34) in the injection pipe (54).
  • the pressure of the refrigerant can be adjusted.
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54) can be adjusted.
  • the control unit (13) is configured such that the temperature (Td) of the refrigerant discharged from the compressor (31a, 31b, 31c) is equal to the discharge high temperature threshold (Tdth), and the temperature (Td) of the refrigerant discharged from the compressor (31a, 31b, 31c) does not fall below the discharge high temperature threshold (Tdth)
  • the refrigeration apparatus increases the opening degree of the supercooling expansion valve (35).
  • the flow rate can be increased, and as a result, the refrigerant passes through the intermediate expansion valve (36a, 36b, 36c) from the supercooling heat exchanger (34) and flows into the intermediate port of the compressor (31a, 31b, 31c).
  • the flow rate (injection amount) of can be increased.
  • the temperature drop amount of the refrigerant in the compressor (31a, 31b, 31c) can be increased, and the temperature (Td) of the refrigerant discharged from the compressor (31a, 31b, 31c) can be reduced.
  • the control unit (13) is discharged from the compressor (31a, 31b, 31c) in the first opening adjustment operation.
  • the refrigerant temperature (Td) is below the discharge high temperature threshold (Tdth)
  • the superheat degree of the refrigerant discharged from the compressor (31a, 31b, 31c) is set to a predetermined target superheat degree.
  • the refrigeration apparatus is characterized by increasing the opening of the intermediate expansion valve (36a, 36b, 36c).
  • the flow rate (injection amount) of the refrigerant flowing into the intermediate port of the compressor (31a, 31b, 31c) is increased by increasing the opening of the intermediate expansion valve (36a, 36b, 36c). Can be made.
  • the temperature drop amount of the refrigerant in the compressor (31a, 31b, 31c) can be increased, and the temperature (Td) of the refrigerant discharged from the compressor (31a, 31b, 31c) can be reduced. it can.
  • the control unit (13) performs the excessive operation in the injection pipe (54) in the second opening adjustment operation.
  • the supercooling expansion valve (35) is opened.
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54) reduces the freezing temperature threshold (Tfth).
  • the refrigeration apparatus is characterized in that the opening degree of the supercooling expansion valve (35) is increased.
  • the refrigerant flowing into the supercooling heat exchanger (34) from the supercooling expansion valve (35) in the injection pipe (54) is reduced.
  • the pressure can be reduced.
  • the supercooling degree of the refrigerant in the supercooling heat exchanger (34) can be increased.
  • increasing the pressure of the refrigerant flowing from the supercooling expansion valve (35) into the supercooling heat exchanger (34) in the injection pipe (54) by increasing the opening degree of the supercooling expansion valve (35). Can do.
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54) can be increased.
  • the refrigerant circuit (20) is configured such that the refrigerant oil is generated from the refrigerant discharged from the compressor (31a, 31b, 31c).
  • An oil separator (41), one end of which is connected to the oil separator (41) and the other end is connected to the supercooling heat exchanger (34) of the injection pipe (54) and the intermediate expansion valve (36a, 36b, 36c), and an oil return expansion valve (42) provided in the oil return pipe (57), and the control section (13).
  • the temperature of the refrigerant flowing between the connection part (P6) with the oil return pipe (57) and the intermediate expansion valve (36a, 36b, 36c) in the injection pipe (54) is A third opening degree adjusting operation for adjusting the opening degree of the oil return expansion valve (42) so as to exceed the freezing temperature threshold (Tfth) is performed. It is a refrigeration device that.
  • the oil return pipe (57) is passed through the oil return pipe (57) from the oil separator (41) and the injection pipe ( 54)
  • the flow rate of the refrigerating machine oil (relatively high-temperature refrigerating machine oil) flowing into 54) can be adjusted.
  • coolant which flows between the connection part (P6) with an oil return piping (57) and intermediate expansion valves (36a, 36b, 36c) in the injection piping (54) can be adjusted.
  • the control unit (13) connects the oil return pipe (57) to the injection pipe (54) in the third opening adjustment operation.
  • the temperature of the refrigerant flowing between the section (P6) and the intermediate expansion valve (36a, 36b, 36c) exceeds the icing temperature threshold (Tfth)
  • the oil return pipe (57) within a predetermined unit time
  • the oil return expansion valve (42) is intermittently set to the open state so that the flow rate of the refrigerating machine oil that passes through the pipe becomes a predetermined flow rate, and the injection pipe (54) is connected to the oil return pipe (57).
  • the oil return expansion valve (42) is intermittent so that the flow rate of the refrigeration oil passing through it increases.
  • the refrigeration apparatus is characterized by being set to an open state.
  • the oil return pipe (54) in the injection pipe (54) is increased by increasing the flow rate of the refrigeration oil (relatively high temperature refrigeration oil) passing through the oil return pipe (57) within a predetermined unit time. 57) and the temperature of the refrigerant flowing between the connection portion (P6) and the intermediate expansion valves (36a, 36b, 36c) can be increased.
  • the compressor by adjusting the opening degree of the intermediate expansion valves (36a, 36b, 36c) in the first opening degree adjusting operation, the compressor ( Since the temperature (Td) of the refrigerant discharged from 31a, 31b, 31c) can be adjusted, the compressors (31a, 31b, 31c) can be protected from high temperature abnormalities.
  • the opening degree of the supercooling expansion valve (35) in the second opening degree adjusting operation the supercooling heat exchanger (34) and the cooling pipe in the injection pipe (54) are set so as to exceed the freezing temperature threshold (Tfth). Since the temperature of the refrigerant flowing between the intermediate expansion valves (36a, 36b, 36c) can be adjusted, icing of the injection pipe (54) can be suppressed.
  • the supercooling expansion valve (35) By increasing the opening, the temperature (Td) of the refrigerant discharged from the compressor (31a, 31b, 31c) can be lowered, and the supercooling heat exchanger (34) in the injection pipe (54) Since the temperature of the refrigerant flowing between the intermediate expansion valves (36a, 36b, 36c) can be raised, the compressor (31a, 31b, 31c) can be protected from high temperature abnormalities while freezing the injection piping (54). Can be suppressed.
  • the compressor (31a, 31b, 31c) in the first opening degree adjusting operation, when the temperature (Td) of the refrigerant discharged from the compressor (31a, 31b, 31c) does not fall below the discharge high temperature threshold (Tdth). Since the temperature of the refrigerant discharged from the compressor (31a, 31b, 31c) can be lowered by increasing the opening of the intermediate expansion valve (36a, 36b, 36c), the compressor (31a, 31b , 31c) can be protected from high temperature abnormalities.
  • Tfth freezing temperature threshold
  • the degree of supercooling of the refrigerant in the supercooling heat exchanger (34) can be increased by decreasing the opening degree of the supercooling expansion valve (35). Therefore, the cooling capacity of the use side heat exchanger (61) can be improved.
  • the opening degree of the oil return expansion valve (42) in the third opening degree adjusting operation in the injection pipe (54) so as to exceed the icing temperature threshold (Tfth). Since the temperature of the refrigerant flowing between the connection part (P6) to the oil return pipe (57) and the intermediate expansion valve (36a, 36b, 36c) can be adjusted, icing of the injection pipe (54) is suppressed. be able to.
  • the connection portion (P6) of the injection piping (54) to the oil return piping (57) and the intermediate expansion valves (36a, 36b, 36c) Increase the flow rate of refrigerating machine oil (relatively high-temperature refrigerating machine oil) that passes through the oil return pipe (57) within a predetermined unit time when the temperature of the refrigerant flowing between them does not exceed the freezing temperature threshold (Tfth)
  • Tfth freezing temperature threshold
  • the temperature of the refrigerant flowing between the connection part (P6) to the oil return pipe (57) and the intermediate expansion valve (36a, 36b, 36c) in the injection pipe (54) can be increased. Freezing of the pipe (54) can be suppressed.
  • FIG. 1 is a piping diagram illustrating a configuration example of a refrigeration apparatus according to an embodiment.
  • FIG. 2 is a piping system diagram for explaining the cooling operation.
  • FIG. 3 is a piping diagram for explaining the defrosting operation.
  • FIG. 4 is a flowchart for explaining opening degree adjustment of the intermediate expansion valve.
  • FIG. 5 is a flowchart for explaining opening adjustment of the supercooling expansion valve.
  • FIG. 6 is a flowchart for explaining opening degree adjustment of the oil return expansion valve.
  • FIG. 1 shows a configuration example of a refrigeration apparatus (10) according to an embodiment.
  • the refrigeration apparatus (10) includes a heat source side unit (11), a plurality of (two in this example) usage side units (12) connected in parallel to the heat source side unit (11), and a controller (13 ).
  • the heat source side unit (11) is provided outside the storage
  • the use side unit (12) is provided inside the storage.
  • the heat source side unit (11) is provided with a heat source side circuit (21) and a heat source side fan (22), and each usage side unit (12) has a usage side circuit (23) and a usage side fan (24). And a drain pan (25).
  • the heat source side circuit (21) of the heat source side unit (11) and the usage side circuit (23) of each usage side unit (12) are connected to the liquid side communication pipe (14) and the gas side communication pipe.
  • the refrigerant circuit (20) connected by (15) and configured to perform a vapor compression refrigeration cycle by circulating the refrigerant is configured.
  • a liquid closing valve (V1) and a gas closing valve (V2) are provided at the liquid end and the gas end of the heat source side circuit (21), respectively.
  • One end of the liquid side connecting pipe (14) and one end of the gas side connecting pipe (15) are connected to the liquid closing valve (V1) and the gas closing valve (V2), respectively.
  • the liquid end and the gas end of each use side circuit (23) are connected to the liquid side connecting pipe (14) and the gas side connecting pipe (15), respectively.
  • the heat source side circuit (21) includes first to third compressors (31a to 31c), a four-way switching valve (32), a heat source side heat exchanger (33), a supercooling heat exchanger (34), Supercooling expansion valve (35), first to third intermediate expansion valves (36a to 36c), receiver (37), heat source side expansion valve (38), first to third check valves (CV1 to CV3), an oil separator (41), and an oil return expansion valve (42).
  • the heat source side circuit (21) includes a discharge refrigerant pipe (51), an intake refrigerant pipe (52), a heat source side liquid refrigerant pipe (53), an injection pipe (54), and a first connection pipe (55).
  • first to third compressors (31a to 31c) are collectively referred to as “compressors (31a, 31b, 31c)”, and the first to third intermediate expansion valves (36a to 36c) are collectively referred to. Is described as “intermediate expansion valve (36a, 36b, 36c)”.
  • the compressors (31a, 31b, 31c) are configured to compress and discharge the sucked refrigerant.
  • the compressors (31a, 31b, 31c) are provided with a suction port, an intermediate port, and a discharge port.
  • the suction port is formed to communicate with the compression chamber (that is, the low-pressure compression chamber) during the suction stroke of the compressor (31a, 31b, 31c).
  • the intermediate port is formed so as to communicate with the compression chamber (that is, the compression chamber of the intermediate pressure) in the middle of the compression stroke of the compressor (31a, 31b, 31c).
  • the discharge port is configured to communicate with the compression chamber (that is, the high-pressure compression chamber) during the discharge stroke of the compressor (31a, 31b, 31c).
  • the compressors (31a, 31b, 31c) are constituted by a scroll type compressor in which a compression chamber is formed between a fixed scroll and a movable scroll that mesh with each other.
  • the capacity of the first compressor (31a) is variable.
  • the first compressor (31a) is configured such that by changing the output frequency of the inverter (not shown), the rotational speed of the electric motor provided therein changes, and the capacity thereof changes. Yes.
  • the capacities of the second and third compressors (31b, 31c) are fixed. That is, the second and third compressors (31b, 31c) have a constant rotational speed of the electric motor provided therein and a constant capacity.
  • the four-way switching valve (32) includes a first state (state indicated by a solid line in FIG. 1) in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other, And the fourth port are in communication with each other and the second port and the third port are in communication with each other (a state indicated by a broken line in FIG. 1).
  • the first port of the four-way switching valve (32) is connected to the discharge port of the compressor (31a, 31b, 31c) by the discharge refrigerant pipe (51), and the second port of the four-way switching valve (32) is the suction refrigerant pipe. (52) is connected to the suction port of the compressor (31a, 31b, 31c).
  • the third port of the four-way switching valve (32) is connected to the gas end of the heat source side heat exchanger (33), and the fourth port of the four-way switching valve (32) is connected to the gas closing valve (V2). .
  • the discharge refrigerant pipe (51) has one end connected to the discharge port of the first, second and third compressors (31a, 31b, 31c). , 51b, 51c) and a discharge junction pipe (51d) connecting the other end of the first, second and third discharge pipes (51a, 51b, 51c) and the first port of the four-way switching valve (32). It is configured.
  • the suction refrigerant pipe (52) has first, second and third suction pipes (52a, 52a, 52) connected at one end to the suction ports of the first, second and third compressors (31a, 31b, 31c), respectively. 52b, 52c) and a suction main pipe (52d) connecting the other end of the first, second and third suction pipes (52a, 52b, 52c) and the second port of the four-way switching valve (32). ing.
  • the liquid end of the heat source side heat exchanger (33) is connected to one end of the heat source side liquid refrigerant pipe (53), and the gas end is connected to the third port of the four-way switching valve (32). Further, a heat source side fan (22) is disposed in the vicinity of the heat source side heat exchanger (33).
  • the heat source side heat exchanger (33) is configured to exchange heat between the refrigerant and the heat source side air (for example, outside air) conveyed by the heat source side fan (22).
  • the heat source side heat exchanger (33) is configured by a cross fin type fin-and-tube heat exchanger.
  • the heat source side liquid refrigerant pipe (53) includes a first heat source side liquid pipe (53a) connecting the liquid end of the heat source side heat exchanger (33) and the receiver (37), a receiver (37), and A second heat source side liquid pipe (53b) connecting the supercooling heat exchanger (34), and a third heat source side liquid pipe (53c) connecting the supercooling heat exchanger (34) and the liquid shut-off valve (V1). ) And.
  • the injection pipe (54) connects the first midway part (P1) of the heat source side liquid refrigerant pipe (53) and the intermediate ports of the compressors (31a, 31b, 31c).
  • the injection pipe (54) includes a first injection main pipe (54m) that connects the first intermediate part (P1) of the heat source side liquid refrigerant pipe (53) and the supercooling heat exchanger (34), and one end.
  • the first, second, and third injection branch pipes (54a, 54b, 54c) are respectively connected to the intermediate ports.
  • injection branch pipe (54a, 54b, 54c) the generic name of the first, second, and third injection branch pipes (54a, 54b, 54c) is referred to as “injection branch pipe (54a, 54b, 54c)”.
  • the supercooling heat exchanger (34) is connected to the heat source side liquid refrigerant pipe (53) and the injection pipe (54), and has a refrigerant flowing through the heat source side liquid refrigerant pipe (53) and a refrigerant flowing through the injection pipe (54).
  • the supercooling heat exchanger (34) includes a first flow path (34a) connected between the second heat source side liquid pipe (53b) and the third heat source side liquid pipe (53c), The second flow path (34b) connected between the 1 injection main pipe (54m) and the second injection main pipe (54n), and the refrigerant flowing through the first flow path (34a) and the second flow path (34b) )
  • the supercooling heat exchanger (34) is configured by a plate heat exchanger.
  • the supercooling expansion valve (35) is provided between the first midway part (P1) of the heat source side liquid refrigerant pipe (53) and the supercooling heat exchanger (34) in the injection pipe (54) (in this example, the first Injection main pipe (54m)). Moreover, the supercooling expansion valve (35) is comprised so that the opening degree can be adjusted.
  • the supercooling expansion valve (35) is constituted by an electronic expansion valve (motorized valve).
  • the intermediate expansion valves (36a, 36b, 36c) are provided between the supercooling heat exchanger (34) and the intermediate ports of the compressors (31a, 31b, 31c) in the injection pipe (54).
  • the first, second, and third intermediate expansion valves (36a, 36b, 36c) correspond to the first, second, and third compressors (31a, 31b, 31c), respectively, It is provided in the second and third injection branch pipes (54a, 54b, 54c).
  • the intermediate expansion valves (36a, 36b, 36c) are configured such that their opening degrees can be adjusted.
  • the intermediate expansion valves (36a, 36b, 36c) are configured by electronic expansion valves (motorized valves).
  • the receiver (37) is connected between the heat source side heat exchanger (33) and the supercooling heat exchanger (34) in the heat source side liquid refrigerant pipe (53), and is connected to a condenser (specifically, heat source side heat The refrigerant condensed in the exchanger (33) or the use side heat exchanger (61)) can be temporarily stored.
  • the receiver (37) has a first heat source side liquid pipe (53a) connected to the top and a second heat source side liquid pipe (53b) connected to the bottom.
  • the first connection pipe (55) connects the second midway part (P2) and the third midway part (P3) of the heat source side liquid refrigerant pipe (53).
  • the second intermediate part (P2) is located between the first intermediate part (P1) and the liquid shut-off valve (V1) in the heat source side liquid refrigerant pipe (53), and the third intermediate part (P3) is on the heat source side It is located between the liquid end of the heat source side heat exchanger (33) and the receiver (37) in the liquid refrigerant pipe (53).
  • the second connection pipe (56) connects the fourth midway part (P4) and the fifth midway part (P5) of the heat source side liquid refrigerant pipe (53).
  • the fourth intermediate part (P4) is located between the supercooling heat exchanger (34) and the first intermediate part (P1) in the heat source side liquid refrigerant pipe (53), and the fifth intermediate part (P5)
  • the heat source side liquid refrigerant pipe (53) is located between the liquid end of the heat source side heat exchanger (33) and the third midway part (P3).
  • the heat source side expansion valve (38) is provided in the second connection pipe (56). Moreover, the heat source side expansion valve (38) is comprised so that adjustment of the opening degree is possible.
  • the heat source side expansion valve (38) is configured by an electronic expansion valve (motor valve).
  • the first check valve (CV1) is provided between the third midway part (P3) and the fifth midway part (P5) of the heat source side liquid refrigerant pipe (53), and the first midway part (P5) to the second midway part (P5) 3 It is configured to allow only the refrigerant flow toward the middle part (P3).
  • the second check valve (CV2) is provided between the first midway part (P1) and the second midway part (P2) of the heat source side liquid refrigerant pipe (53), and the second check valve (CV2) 2 It is configured to allow only the refrigerant flow toward the middle part (P2).
  • the third check valve (CV3) is provided in the first connection pipe (55), and the refrigerant flows from the second midway part (P2) to the third midway part (P3) of the heat source side liquid refrigerant pipe (53). It is configured to allow only.
  • the oil separator (41) is provided in the discharge refrigerant pipe (51) (in this example, the discharge merging pipe (51d)), and separates refrigeration oil from the refrigerant discharged from the compressor (31a, 31b, 31c). And can be stored inside.
  • the oil return pipe (57) is a pipe for supplying the refrigeration oil (relatively high temperature refrigeration oil) stored in the oil separator (41) to the injection pipe (54), and one end of the oil return pipe (57) 41) and the other end is in the middle of the injection pipe (54) between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) (in this example, the second injection main pipe ( 54n) is connected to the middle part).
  • the oil return expansion valve (42) is provided in the oil return pipe (57).
  • the oil return expansion valve (42) is configured to be adjustable in opening.
  • the oil return expansion valve (42) is constituted by an electronic expansion valve (motorized valve).
  • the utilization side circuit (23) has a utilization side heat exchanger (61), a utilization side on-off valve (62), and a utilization side expansion valve (63).
  • the use side circuit (23) is provided with a use side liquid refrigerant pipe (71) and a use side gas refrigerant pipe (72).
  • the liquid end of the use side heat exchanger (61) is connected to the liquid side connection pipe (14) by the use side liquid refrigerant pipe (71), and the gas end is connected to the gas side by the use side gas refrigerant pipe (72). Connected to pipe (15).
  • the utilization side fan (24) is arrange
  • the use side heat exchanger (61) is configured to exchange heat between the refrigerant and the use side air (for example, internal air) conveyed by the use side fan (24).
  • the use side heat exchanger (61) is configured by a cross-fin type fin-and-tube heat exchanger.
  • Use side liquid refrigerant pipe, Use side gas refrigerant pipe One end of the use side liquid refrigerant pipe (71) is connected to the liquid side connecting pipe (14), and the other end is connected to the liquid end of the use side heat exchanger (61).
  • the use side liquid refrigerant pipe (71) has one end of the first use side liquid pipe (71a) connected to the liquid side connecting pipe (14) and one end of the first use side liquid pipe (71a).
  • the drain pan pipe (71b) connected to the other end, and the second usage side liquid pipe (71c) connecting the other end of the drain pan pipe (71b) and the liquid end of the usage side heat exchanger (61). ing.
  • the use side gas refrigerant pipe (72) has one end connected to the gas end of the use side heat exchanger (61) and the other end connected to the gas side connecting pipe (15).
  • the use side on-off valve (62) and the use side expansion valve (63) are provided in series with the use side liquid refrigerant pipe (71) (in this example, the second use side liquid pipe (71c)).
  • the use side on-off valve (62) is configured to be switchable.
  • the use side on-off valve (62) is constituted by a solenoid valve.
  • the use side expansion valve (63) is configured such that its opening degree can be adjusted.
  • the use side expansion valve (63) is constituted by an external pressure equalization type temperature automatic expansion valve.
  • the use side expansion valve (63) includes a temperature sensing tube (63a) provided in the use side gas refrigerant pipe (72) and a pressure equalizing pipe connected to a midway part of the use side gas refrigerant pipe (72). (63b), and the opening degree is adjusted according to the temperature of the temperature sensing cylinder (63a) and the refrigerant pressure of the pressure equalizing pipe (63b).
  • the drain pan (25) is installed on the lower side of the use side heat exchanger (61), and is configured to collect frost and condensed water falling from the surface of the use side heat exchanger (61). Further, a drain pan pipe (71b) which is a part of the use side liquid refrigerant pipe (71) is disposed inside the drain pan (25).
  • the liquid refrigerant pipe (50) is constituted by the heat source side liquid refrigerant pipe (53) and the liquid side connecting pipe (14). That is, the liquid end of the heat source side heat exchanger (33) is connected to the liquid refrigerant pipe (50).
  • the use side liquid refrigerant pipe (71) connects the liquid end of the use side heat exchanger (61) and the liquid refrigerant pipe (50).
  • the injection pipe (54) connects the midway part (first midway part (P1)) of the liquid refrigerant pipe (50) and the intermediate ports of the compressors (31a, 31b, 31c).
  • the supercooling heat exchanger (34) is connected to the liquid refrigerant pipe (50) and the injection pipe (54) to exchange heat between the refrigerant flowing through the liquid refrigerant pipe (50) and the refrigerant flowing through the injection pipe (54). It is configured as follows.
  • the refrigeration apparatus (10) is provided with various sensors such as first to third discharge refrigerant temperature sensors (81a to 81c) and an injection refrigerant temperature sensor (82).
  • first to third discharge refrigerant temperature sensors (81a to 81c) and an injection refrigerant temperature sensor (82).
  • discharge refrigerant temperature sensor (81a, 81b, 81c) is referred to as “discharge refrigerant temperature sensor (81a, 81b, 81c)”.
  • the discharged refrigerant temperature sensor (81a, 81b, 81c) is configured to detect the temperature of the refrigerant discharged from the compressor (31a, 31b, 31c) (hereinafter referred to as discharged refrigerant temperature (Td)). Yes.
  • the first, second, and third discharge refrigerant temperature sensors (81a, 81b, 81c) correspond to the first, second, and third intermediate expansion valves (36a, 36b, 36c), respectively. It is installed in the vicinity of the discharge ports of the first, second and third compressors (31a, 31b, 31c), and detects the temperature of the refrigerant at the installation location as the discharged refrigerant temperature (Td).
  • the injection refrigerant temperature sensor (82) is disposed between the supercooling heat exchanger (34) and the intermediate expansion valve (36a, 36b, 36c) in the injection pipe (54) (preferably, the injection pipe (54) and the oil return pipe. (57) is configured to detect the temperature of the refrigerant flowing between the connection portion (P6) and the intermediate expansion valve (36a, 36b, 36c).
  • the injection refrigerant temperature sensor (82) is installed between the connection part (P6) and the intermediate expansion valves (36a, 36b, 36c) in the second injection main pipe (54n), and the temperature of the refrigerant at the installation location.
  • injection refrigerant temperature (Tinj) Is detected as the temperature of the refrigerant flowing between the connecting portion (P6) and the intermediate expansion valves (36a, 36b, 36c) in the second injection main pipe (54n) (hereinafter referred to as injection refrigerant temperature (Tinj)).
  • the controller (13) controls each part of the refrigeration apparatus (10) to control the operation of the refrigeration apparatus (10). Specifically, the controller (13) determines whether the compressor (31a, 31b, 31c) is based on detection values of various sensors (discharge refrigerant temperature sensor (81a, 81b, 81c), injection refrigerant temperature sensor (82), etc.). ) And various fans (heat source side fan (22), use side fan (24)) and various valves (four-way switching valve (32), supercooling expansion valve (35), intermediate expansion valve (36a, 36b, 36c), heat source The side expansion valve (38), oil return expansion valve (42), and use side on-off valve (62)) are controlled. In the refrigeration apparatus (10), a cooling operation for cooling the inside of the refrigerator and a defrosting operation for defrosting the use side heat exchanger (61) are performed.
  • the cooling operation will be described with reference to FIG.
  • the heat source side heat exchanger (33) serves as a condenser
  • the supercooling heat exchanger (34) serves as a subcooler
  • the use side heat exchanger (61) serves as an evaporator. Is done.
  • the four-way selector valve (32) is set to the first state.
  • the discharge port of the compressor (31a, 31b, 31c) and the gas end of the heat source side heat exchanger (33) communicate with each other, and the suction port of the compressor (31a, 31b, 31c) and the gas side communication pipe ( 15) communicate with.
  • the compressors (31a, 31b, 31c), the heat source side fan (22), and the use side fan (24) are set in a driving state.
  • the opening degree of the supercooling expansion valve (35) is adjusted, the opening degree of the intermediate expansion valves (36a, 36b, 36c) is adjusted, the heat source side expansion valve (38) is set to the fully closed state, and the oil return The expansion valve (42) is intermittently set to the open state.
  • the use side on-off valve (62) is set to either the open state or the closed state according to the cooling load in the refrigerator, and the outlet of the use side heat exchanger (61)
  • the degree of opening of the utilization side expansion valve (63) is adjusted according to the temperature of the temperature sensing cylinder (63a) and the refrigerant pressure of the pressure equalizing pipe (63b) so that the degree of superheat of the refrigerant in the refrigerant becomes a predetermined degree of superheat.
  • FIG. 2 the case where the use side on-off valve (62) is set to the open state in all the use side units (12) is shown.
  • the refrigerant discharged from the compressor (31a, 31b, 31c) passes through the oil separator (41) in the discharge refrigerant pipe (51), and then passes through the four-way switching valve (32) to the heat source side heat exchanger ( 33), in the heat source side heat exchanger (33), dissipates heat to heat source side air (for example, outside air) and condenses.
  • heat source side air for example, outside air
  • the refrigerant (high-pressure refrigerant) flowing out from the heat source side heat exchanger (33) passes through the first check valve (CV1) in the first heat source side liquid pipe (53a), and then the receiver (37) and the second heat source side A refrigerant (passing through the liquid pipe (53b) in order and flowing into the first flow path (34a) of the supercooling heat exchanger (34) and flowing through the second flow path (34b) of the supercooling heat exchanger (34) (
  • the refrigerant is absorbed by the intermediate pressure refrigerant) and supercooled.
  • the refrigerant that has flowed out of the first flow path (34a) of the supercooling heat exchanger (34) flows into the third heat source side liquid pipe (53c).
  • the refrigerant flowing into the first injection main pipe (54m) is depressurized in the supercooling expansion valve (35) and flows into the second flow path (34b) of the supercooling heat exchanger (34), and the supercooling heat exchanger ( The heat is absorbed from the refrigerant (high-pressure refrigerant) flowing through the first flow path (34a) of 34).
  • the refrigerant that has flowed out of the second flow path (34b) of the supercooling heat exchanger (34) passes through the second injection main pipe (54n) and flows into the injection branch pipes (54a, 54b, 54c).
  • the refrigerant flowing into the injection branch pipes (54a, 54b, 54c) is decompressed by the intermediate expansion valves (36a, 36b, 36c) and flows into the intermediate ports of the compressors (31a, 31b, 31c).
  • the refrigerant that has passed through the intermediate port and has flowed into the compressor (31a, 31b, 31c) is mixed with the refrigerant (specifically, the refrigerant in the compression chamber) in the compressor (31a, 31b, 31c). That is, the refrigerant in the compressor (31a, 31b, 31c) is compressed while being cooled.
  • the refrigerant flowing into the liquid side communication pipe (14) flows into the first usage side liquid pipe (71a) of the usage side unit (12) in which the usage side on-off valve (62) is set in the open state.
  • the refrigerant flowing into the first usage-side liquid pipe (71a) passes through the drain pan pipe (71b) and becomes the second usage. It flows into the side liquid pipe (71c).
  • the refrigerant flowing into the second usage-side liquid pipe (71c) passes through the open-side usage-side on-off valve (62) and is then depressurized at the usage-side expansion valve (63) to the usage-side heat exchanger (61).
  • the refrigerant flowing out of the use side heat exchanger (61) is divided into the use side gas refrigerant pipe (72), the gas side communication pipe (15), the gas shut-off valve (V2), the four-way switching valve (32), and the suction refrigerant pipe (52 ) In order, and is sucked into the suction ports of the compressors (31a, 31b, 31c).
  • the refrigeration oil is separated from the refrigerant (that is, the refrigerant discharged from the compressor (31a, 31b, 31c)), and the refrigeration oil is stored in the oil separator (41). .
  • the oil return expansion valve (42) is set in the open state, the refrigerating machine oil (relatively high temperature refrigerating machine oil) stored in the oil separator (41) passes through the oil return pipe (57) and is It flows into 2 injection main pipes (54n).
  • the refrigerating machine oil that has flowed into the second injection main pipe (54n) joins the refrigerant flowing through the second injection main pipe (54n), and then the intermediate expansion valve (36a, 36b, 36c) in the injection branch pipe (54a, 54b, 54c). And flows into the intermediate ports of the compressors (31a, 31b, 31c).
  • the flow rate (injection amount) of the refrigerant flowing into the intermediate port of the compressor (31a, 31b, 31c) is adjusted by adjusting the opening degree of the intermediate expansion valve (36a, 36b, 36c). be able to.
  • the temperature drop amount of the refrigerant in the compressor (31a, 31b, 31c) is adjusted.
  • the temperature of the refrigerant discharged from the compressor (31a, 31b, 31c) that is, the discharged refrigerant) Temperature (Td)
  • Td discharged refrigerant
  • the opening degree adjustment of the intermediate expansion valves (36a, 36b, 36c) in the cooling operation will be described in detail later.
  • the opening degree of the supercooling expansion valve (35) by adjusting the opening degree of the supercooling expansion valve (35), the second flow path of the supercooling heat exchanger (34) from the supercooling expansion valve (35) in the injection pipe (54) ( The pressure of the refrigerant flowing into 34b) can be adjusted.
  • the supercooling degree of the refrigerant in the supercooling heat exchanger (34) (specifically, the supercooling degree of the refrigerant flowing out from the first flow path (34a) of the supercooling heat exchanger (34))
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) can be adjusted.
  • the opening degree of the supercooling expansion valve (35) it flows from the supercooling expansion valve (35) into the second flow path (34b) of the supercooling heat exchanger (34) in the injection pipe (54).
  • the flow rate of the refrigerant to be adjusted can be adjusted.
  • the flow rate (injection amount) of can be adjusted.
  • the opening degree adjustment of the supercooling expansion valve (35) in the cooling operation will be described in detail later.
  • the oil return expansion valve (42) is intermittently set to the open state so that the refrigerating machine oil stored in the oil separator (41) is allowed to flow intermittently through the oil return pipe (57). Can do. Thereby, refrigerating machine oil can be effectively returned in a compressor (31a, 31b, 31c).
  • the opening degree adjustment of the oil return expansion valve (42) in the cooling operation will be described in detail later.
  • the four-way selector valve (32) is set to the second state.
  • the discharge port of the compressor (31a, 31b, 31c) and the gas side communication pipe (15) communicate with each other, and the suction port of the compressor (31a, 31b, 31c) and the heat source side heat exchanger (33) The gas end communicates.
  • the compressors (31a, 31b, 31c) and the heat source side fan (22) are set to the driving state, and the use side fan (24) is set to the stop state.
  • the supercooling expansion valve (35) is set in a fully closed state
  • the intermediate expansion valves (36a, 36b, 36c) are set in a fully closed state
  • the degree of superheat of the refrigerant at the outlet of the heat source side heat exchanger (33) The opening degree of the heat source side expansion valve (38) is adjusted so that the predetermined degree of superheat is reached, and the oil return expansion valve (42) is set to a fully closed state.
  • the use side on-off valve (62) is set in an open state
  • the use side expansion valve (63) is in a fully open state.
  • the refrigerant discharged from the compressor (31a, 31b, 31c) passes through the oil separator (41) in the discharge refrigerant pipe (51), and then passes through the four-way switching valve (32) and the gas shut-off valve (V2) in order. Passes through and flows into the gas side connecting pipe (15).
  • the refrigerant flowing into the gas side communication pipe (15) flows into the use side gas refrigerant pipe (72) of each use side unit (12).
  • the refrigerant that has flowed into the usage-side gas refrigerant pipe (72) flows into the usage-side heat exchanger (61), dissipates heat and condenses in the usage-side heat exchanger (61).
  • the refrigerant that has flowed out of the usage-side heat exchanger (61) flows into the second usage-side liquid pipe (71c) and enters the fully-opened usage-side expansion valve (63) and the opened usage-side on-off valve (62). After passing in order, it passes through the drain pan pipe (71b) and the first usage side liquid pipe (71a) in order and flows into the liquid side connecting pipe (14).
  • the refrigerant that has flowed into the liquid side connecting pipe (14) passes through the liquid closing valve (V1) and flows into the third heat source side liquid pipe (53c).
  • the refrigerant flowing into the third heat source side liquid pipe (53c) flows into the first connection pipe (55), passes through the second check valve (CV2) in the first connection pipe (55), and then passes through the first heat source side. It flows into the liquid pipe (53a).
  • the refrigerant flowing into the first heat source side liquid pipe (53a) sequentially passes through the receiver (37), the second heat source side liquid pipe (53b), and the first flow path (34a) of the supercooling heat exchanger (34). And flows into the third heat source side liquid pipe (53c).
  • the refrigerant that has flowed into the third heat source side liquid pipe (53c) flows into the second connection pipe (56).
  • the refrigerant flowing into the second connection pipe (56) is decompressed by the heat source side expansion valve (38) and flows into the first heat source side liquid pipe (53a).
  • the refrigerant flowing into the first heat source side liquid pipe (53a) flows into the heat source side heat exchanger (33), and absorbs heat from the heat source side air (for example, outside air) in the heat source side heat exchanger (33). Evaporate.
  • the refrigerant flowing out from the heat source side heat exchanger (33) sequentially passes through the four-way switching valve (32) and the suction refrigerant pipe (52) and is sucked into the suction ports of the compressors (31a, 31b, 31c).
  • the refrigerant (high-temperature refrigerant) flowing out from the use side heat exchanger (61) serving as a condenser flows through the drain pan pipe (71b).
  • the refrigerant flowing through the drain pan pipe (71b) heats and melts the residual frost in the drain pan (25) (that is, ice blocks generated by freezing frost and condensed water collected in the drain pan (25)).
  • the water generated by melting the residual frost is discharged through a drainage pipe (not shown).
  • the controller (13) performs the first opening adjustment operation (steps (ST11 to ST13)) every time a predetermined operation time elapses in the cooling operation.
  • the controller (13) adjusts the opening of the intermediate expansion valve (36a, 36b, 36c) so that the discharge refrigerant temperature (Td) is lower than the predetermined discharge high temperature threshold (Tdth).
  • the controller (13) performs the first opening adjustment operation for each of the first to third intermediate expansion valves (36a to 36c).
  • the controller (13) adjusts the first opening degree with respect to the first intermediate expansion valve (36a) corresponding to the first compressor (31a) based on the detection value of the first discharge refrigerant temperature sensor (81a). Adjust the operation. In the first opening adjustment operation, the following processing is performed.
  • the controller (13) determines whether or not the discharge refrigerant temperature (Td) is lower than the discharge high temperature threshold (Tdth) (step (ST11)).
  • the discharge high temperature threshold (Tdth) is set to a limit value (maximum value, for example, 105 ° C.) of the discharge refrigerant temperature (Td) that can be considered that no high temperature abnormality occurs in the compressor (31a, 31b, 31c). If the discharge refrigerant temperature (Td) is below the discharge high temperature threshold (Tdth), the process proceeds to step (ST12), and if not, the process proceeds to step (ST13).
  • the controller (13) determines the superheat degree of the refrigerant discharged from the compressor (31a, 31b, 31c) (hereinafter referred to as the discharge superheat degree).
  • the degree of opening of the intermediate expansion valves (36a, 36b, 36c) is adjusted so that (description) becomes a predetermined target superheat (for example, 15 ° C.).
  • the controller (13) increases the opening degree of the intermediate expansion valves (36a, 36b, 36c) when the discharge superheat degree exceeds the target superheat degree.
  • the flow rate (injection amount) of the refrigerant flowing into the intermediate port of the compressor (31a, 31b, 31c) can be increased to increase the temperature decrease amount of the refrigerant in the compressor (31a, 31b, 31c).
  • the temperature of the refrigerant discharged from the compressor (31a, 31b, 31c) that is, the discharged refrigerant temperature (Td)
  • Td discharged refrigerant temperature
  • the controller (13) decreases the opening degree of the intermediate expansion valves (36a, 36b, 36c) when the discharge superheat degree is lower than the target superheat degree.
  • the flow rate (injection amount) of the refrigerant flowing into the intermediate port of the compressor (31a, 31b, 31c) can be reduced to reduce the temperature drop amount of the refrigerant in the compressor (31a, 31b, 31c). it can.
  • the temperature of the refrigerant discharged from the compressor (31a, 31b, 31c) that is, the discharged refrigerant temperature (Td)
  • Td discharged refrigerant temperature
  • the opening degree of the intermediate expansion valve (36a, 36b, 36c) is adjusted so that the superheat degree of the refrigerant discharged from the compressor (31a, 31b, 31c) becomes a predetermined target superheat degree.
  • the flow rate (injection amount) of the refrigerant flowing into the intermediate port of the compressor (31a, 31b, 31c) can be appropriately adjusted.
  • the controller (13) When the opening of the intermediate expansion valve (36a, 36b, 36c) is at the maximum opening (for example, fully open state) in step (ST13), the controller (13) has the intermediate expansion valve (36a, 36b, Maintain the maximum opening at 36c).
  • the controller (13) performs the processing shown in FIG. 5 (steps (ST20 to ST24)) every time a predetermined operation time elapses in the cooling operation.
  • Step (ST20)> the controller (13) determines whether or not the discharge refrigerant temperature (Td) is below the discharge high temperature threshold (Tdth). If the discharge refrigerant temperature (Td) is lower than the discharge high temperature threshold (Tdth), the process proceeds to step (ST21), and if not, the process proceeds to step (ST24).
  • the controller (13) performs the second opening degree adjusting operation.
  • the controller (13) causes the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54) (this example)
  • the opening degree of the supercooling expansion valve (35) is adjusted so that the injection refrigerant temperature (Tinj)) exceeds a predetermined freezing temperature threshold value (Tfth).
  • the icing temperature threshold (Tfth) is set to a limit value (minimum value, for example, 0 ° C.) of the injection refrigerant temperature (Tinj) at which the injection pipe (54) can be regarded as not icing.
  • Tfth a limit value of the injection refrigerant temperature (Tinj) at which the injection pipe (54) can be regarded as not icing.
  • Step (ST22)> When the injection refrigerant temperature (Tinj) exceeds the freezing temperature threshold (Tfth), the controller (13) decreases the opening degree of the supercooling expansion valve (35) by a predetermined decrease amount (step (ST22)). ). Thereby, the pressure of the refrigerant
  • the controller (13) increases the opening degree of the supercooling expansion valve (35) by a predetermined increase amount (step ( ST23)).
  • coolant which flows in into the 2nd flow path (34b) of a supercooling heat exchanger (34) from a supercooling expansion valve (35) can be raised in an injection piping (54).
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valve (36a, 36b, 36c) in the injection pipe (54) (in this example, the injection refrigerant temperature (Tinj)) is increased. Can be made.
  • the flow rate of the refrigerant flowing from the supercooling expansion valve (35) into the second flow path (34b) of the supercooling heat exchanger (34) can be increased, and the intermediate expansion valve (
  • the flow rate (injection amount) of the refrigerant passing through 36a, 36b, 36c) and flowing into the intermediate port of the compressor (31a, 31b, 31c) can be increased.
  • the temperature drop amount of the refrigerant in the compressor (31a, 31b, 31c) can be increased, and the temperature of the refrigerant discharged from the compressor (31a, 31b, 31c) (that is, the discharged refrigerant temperature (Td )) Can be reduced.
  • the supercooling expansion valve (35) By increasing the opening degree of the supercooling expansion valve (35), it flows from the supercooling expansion valve (35) into the second flow path (34b) of the supercooling heat exchanger (34) in the injection pipe (54).
  • the pressure of the refrigerant can be increased.
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valve (36a, 36b, 36c) in the injection pipe (54) (in this example, the injection refrigerant temperature (Tinj)) is increased. Can be made.
  • the controller (13) determines that the opening degree of the supercooling expansion valve (35) when the opening degree of the supercooling expansion valve (35) is the minimum opening degree (for example, the fully closed state) in step (ST22). Is maintained at the minimum opening. Further, the controller (13) opens the supercooling expansion valve (35) when the opening degree of the supercooling expansion valve (35) is the maximum opening degree (for example, fully open state) in step (ST23, ST24). Keep the degree at maximum opening.
  • the controller (13) performs a third opening adjustment operation (steps (ST31 to ST33)) every time a predetermined operation time elapses in the cooling operation.
  • the controller (13) causes the refrigerant flowing between the connection part (P6) to the oil return pipe (57) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54).
  • the opening degree of the oil return expansion valve (42) is adjusted so that the temperature (in this example, the injection refrigerant temperature (Tinj)) exceeds the freezing temperature threshold (Tfth).
  • the third opening adjustment operation the following processing is performed.
  • Step (ST32)> When the injection refrigerant temperature (Tinj) exceeds the freezing temperature threshold (Tfth), the controller (13) sends the flow rate of refrigerating machine oil (that is, the oil return amount) that passes through the oil return pipe (57) within a predetermined unit time.
  • the oil return expansion valve (42) is intermittently set to the open state so that the flow rate becomes a predetermined flow rate (normal flow rate).
  • the controller (13) determines that the length of the open state time during which the oil return expansion valve (42) is set to the open state within a predetermined unit time is a predetermined time length (normal time length). Then, the oil return expansion valve (42) is intermittently set to the open state.
  • the controller (13) sets the opening when the oil return expansion valve (42) is open to a predetermined opening (normal opening).
  • Step (ST33)> when the injection refrigerant temperature (Tinj) does not exceed the freezing temperature threshold (Tfth), the controller (13) sends the flow rate of refrigerating machine oil (that is, oil) passing through the oil return pipe (57) within a predetermined unit time.
  • the oil return expansion valve (42) is intermittently set to an open state so that the (return amount) increases by a predetermined increase amount (step (ST33)).
  • the controller (13) causes the oil return expansion valve (42) to be intermittent so that the open state time during which the oil return expansion valve (42) is set to the open state becomes longer within a predetermined unit time. Set to open.
  • the controller (13) increases the opening when the oil return expansion valve (42) is open.
  • the controller (13) returns the oil return when the flow rate of the refrigerating machine oil passing through the oil return pipe (57) within the predetermined unit time (ie, the oil return amount) is the maximum flow rate in step (ST33).
  • the oil return expansion valve (42) is controlled to open and close so that the amount is maintained at the maximum flow rate.
  • the controller (13) determines that the length of the open state time during which the oil return expansion valve (42) is set to the open state within a predetermined unit time is the same as the maximum time length (for example, unit time). The length of the open state time is maintained at the maximum time length, and the opening and closing of the oil return expansion valve (42) is controlled.
  • the controller (13) may determine whether the oil return expansion valve (42) is open when the opening when the oil return expansion valve (42) is open is a maximum opening (for example, fully open). The opening and closing of the oil return expansion valve (42) is controlled so that the opening at that time is maintained at the maximum opening.
  • the compressor (31a, 31b, 31c) is set to be lower than the discharge high temperature threshold (Tdth).
  • the temperature (Td) of the refrigerant discharged from can be adjusted.
  • a compressor (31a, 31b, 31c) can be protected from a high temperature abnormality.
  • the supercooling heat exchanger (34) and the cooling pipe in the injection pipe (54) are set so as to exceed the freezing temperature threshold (Tfth).
  • the temperature of the refrigerant flowing between the intermediate expansion valves (36a, 36b, 36c) can be adjusted. Thereby, icing (specifically, the progress of icing) of the injection pipe (54) can be suppressed.
  • the temperature of the refrigerant flowing between the supercooling heat exchanger (34) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54) is the freezing temperature threshold (Tfth).
  • Tfth freezing temperature threshold
  • the degree of supercooling of the refrigerant in the supercooling heat exchanger (34) can be increased by decreasing the opening degree of the supercooling expansion valve (35). Thereby, the cooling capacity of the use side heat exchanger (61) can be improved.
  • the oil separator (41) passes through the oil return pipe (57) and flows into the injection pipe (54).
  • the flow rate of the refrigeration oil (relatively high temperature refrigeration oil) can be adjusted.
  • coolant which flows between the connection part (P6) with an oil return piping (57) and intermediate expansion valves (36a, 36b, 36c) in the injection piping (54) can be adjusted.
  • the temperature of the refrigerant flowing between the connection part (P6) of the oil return pipe (57) and the intermediate expansion valves (36a, 36b, 36c) in the injection pipe (54) is frozen.
  • the injection pipe (54) by increasing the flow rate of refrigeration oil (relatively hot refrigeration oil) that passes through the oil return pipe (57) within a predetermined unit time when the temperature threshold (Tfth) is not exceeded.
  • the temperature of the refrigerant flowing between the connection part (P6) to the oil return pipe (57) and the intermediate expansion valves (36a, 36b, 36c) can be raised. Thereby, icing of the injection pipe (54) can be suppressed.
  • the refrigerant circuit (20) is provided with three compressors (first to third compressors (31a to 31c)), but the number of compressors is one. Or two or four or more.
  • the above-described refrigeration apparatus is useful as a refrigeration apparatus that cools the inside of a warehouse.

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)
PCT/JP2016/001846 2015-04-28 2016-03-30 冷凍装置 WO2016174822A1 (ja)

Priority Applications (2)

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ES16786103T ES2879920T3 (es) 2015-04-28 2016-03-30 Aparato de refrigeración
EP16786103.8A EP3290825B1 (de) 2015-04-28 2016-03-30 Kühlvorrichtung

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JP2015-092150 2015-04-28
JP2015092150A JP5971377B1 (ja) 2015-04-28 2015-04-28 冷凍装置

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JP2018084376A (ja) * 2016-11-24 2018-05-31 ダイキン工業株式会社 冷凍装置
EP3546850A4 (de) * 2016-11-24 2020-08-19 Daikin Industries, Ltd. Kühlvorrichtung

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JP6142896B2 (ja) * 2015-04-28 2017-06-07 ダイキン工業株式会社 冷凍装置
JP6319388B2 (ja) * 2016-09-12 2018-05-09 ダイキン工業株式会社 冷凍装置
CN109373634B (zh) * 2018-10-29 2020-07-31 宁波奥克斯电气股份有限公司 一种回油控制方法、装置及空调器
CN110173934B (zh) * 2019-05-29 2021-02-19 南京天加环境科技有限公司 一种燃气热泵多联机过冷结构的控制方法
IT202200005252A1 (it) * 2022-03-17 2023-09-17 General Gas S R L Metodo di controllo di un impianto di refrigerazione con sottoraffreddamento meccanico e relativo impianto di refrigerazione

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JP2012137207A (ja) * 2010-12-24 2012-07-19 Mitsubishi Electric Corp 冷凍サイクル装置
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JP2009287800A (ja) * 2008-05-27 2009-12-10 Daikin Ind Ltd 冷凍装置
JP2012137207A (ja) * 2010-12-24 2012-07-19 Mitsubishi Electric Corp 冷凍サイクル装置
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JP2018084376A (ja) * 2016-11-24 2018-05-31 ダイキン工業株式会社 冷凍装置
WO2018097138A1 (ja) * 2016-11-24 2018-05-31 ダイキン工業株式会社 冷凍装置
EP3546850A4 (de) * 2016-11-24 2020-08-19 Daikin Industries, Ltd. Kühlvorrichtung

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ES2879920T3 (es) 2021-11-23
JP5971377B1 (ja) 2016-08-17
EP3290825B1 (de) 2021-05-19
JP2016205792A (ja) 2016-12-08
EP3290825A4 (de) 2018-12-19

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