US20090126399A1 - Refigeration system - Google Patents

Refigeration system Download PDF

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Publication number
US20090126399A1
US20090126399A1 US11/921,499 US92149906A US2009126399A1 US 20090126399 A1 US20090126399 A1 US 20090126399A1 US 92149906 A US92149906 A US 92149906A US 2009126399 A1 US2009126399 A1 US 2009126399A1
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Prior art keywords
heat exchanger
refrigeration
refrigerant
compressor
freezer
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US11/921,499
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English (en)
Inventor
Masaai Takegami
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Daikin Industries Ltd
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Daikin Industries Ltd
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Assigned to DAIKIN INDUSTRIES, LTD. reassignment DAIKIN INDUSTRIES, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NAKAJIMA, HIROTO, TANIMOTO, KENJI, KONDO, AZUMA, NOMURA, KAZUYOSHI, ODA, YOSHINARI, TAKEGAMI, MASAAKI, UENO, TAKEO
Publication of US20090126399A1 publication Critical patent/US20090126399A1/en
Abandoned legal-status Critical Current

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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
    • F25B29/00—Combined heating and refrigeration systems, e.g. operating alternately or simultaneously
    • 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
    • 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
    • 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
    • F25B6/00—Compression machines, plants or systems, with several condenser circuits
    • F25B6/02—Compression machines, plants or systems, with several condenser circuits arranged in parallel
    • 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
    • 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
    • F25B2313/0231—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units with simultaneous cooling and heating
    • 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
    • F25B2313/0233—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in parallel arrangements
    • F25B2313/02331—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in parallel arrangements during cooling
    • 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
    • F25B2400/0751—Details of compressors or related parts with parallel compressors the compressors having different capacities
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/13—Economisers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/02—Compressor control
    • F25B2600/021—Inverters therefor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the present invention relates to a refrigeration system having a refrigerant circuit of a vapor compression type refrigeration cycle such that plural lines of refrigeration circuits each having a refrigeration heat exchanger are connected in parallel to an outdoor circuit provided with an outdoor heat exchanger and a compression mechanism, and in particular, to a refrigeration system such that at least one line of refrigeration circuit has an auxiliary compressor connected in series to a refrigeration heat exchanger.
  • a refrigeration system for conducting a refrigeration-cycle has been known and has been widely used as a refrigeration unit of a chiller unit or a freezer unit (or a chiller showcase or a freezer showcase) for storing foods and the like.
  • patent document 1 discloses a refrigeration system provided with plural heat exchangers for refrigerating the interior of a chiller unit or the like.
  • a chiller heat exchanger for chilling the interior of a chiller showcase of a chiller unit and a freezer heat exchanger for freezing the interior of a freezer showcase of a freezer unit are connected in parallel to one outdoor unit.
  • an auxiliary compressor is interposed between the freezer heat exchanger and the outdoor unit in addition to a compression mechanism (main compressor) of the outdoor unit.
  • a single-stage refrigeration cycle which uses the chiller heat exchanger as an evaporator
  • a two-stage refrigeration cycle which uses the freezer heat exchanger as an evaporator and uses the auxiliary compressor as a low-stage compressor, are conducted by one refrigerant circuit.
  • the refrigeration system of this kind presents a problem that when moisture in air adheres to a chiller heat exchanger or a freezer heat exchanger and freezes there, the refrigeration of air in the refrigerator is impaired by the adhering frost. For this reason, it is necessary to melt the frost adhering to these heat exchangers, that is, to defrost the refrigeration heat exchangers.
  • the evaporation temperature of refrigerant in the freezer heat exchange is set comparatively low and hence the problem of the frost developed in the freezer heat exchanger becomes particularly serious.
  • the refrigeration system conducts a refrigeration cycle for circulating refrigerant through the auxiliary compressor, the freezer heat exchanger, an expansion valve for the chiller heat exchanger, and the chiller heat exchanger in this order to defrost the freezer heat exchanger.
  • the refrigerant circuit of the refrigeration system is provided with a switching mechanism capable of switching between a first operation for a cooling operation in which the auxiliary compressor sucks refrigerant from the freezer heat exchanger and discharges the refrigerant to the suction side of the compression mechanism of the outdoor unit and a second operation for a defrosting operation in which the auxiliary compressor sucks refrigerant from the chiller heat exchanger and discharges the refrigerant to the freezer heat exchanger.
  • the refrigerant circuit sends the refrigerant from the freezer heat exchanger to the chiller heat exchanger while performing the second operation.
  • the refrigerant absorbs heat from air in the chiller showcase by the chiller heat exchanger, thereby being evaporated, and is sucked by the auxiliary compressor and is compressed by the auxiliary compressor and is sent to the freezer heat exchanger.
  • the refrigerant dissipates heat in the freezer heat exchanger, thereby being condensed, and the heat melts the frost.
  • the condensed refrigerant is expanded by an expansion valve before the chiller heat exchanger and then is returned to the chiller heat exchanger and absorbs heat from the air in the chiller showcase, thereby being evaporated.
  • the freezer heat exchanger is defrosted by the use of heat that the refrigerant recovers from the air in the chiller showcase when the refrigerant flows through the auxiliary compressor, the freezer heat exchanger, the expansion valve, and the chiller heat exchanger in this order.
  • Patent document 1 Japanese Unexamined Patent Publication No. 2004-353995
  • the refrigeration system when there arises a problem that moisture in air adheres to a chiller heat exchanger and freezes there to develop frost, whereby the refrigeration of air in the refrigerator is impaired, it is impossible to defrost the chiller heat exchanger by the heat of the refrigerant.
  • the refrigeration system needs to be provided with a defrosting mechanism such as an electric heater in addition to the refrigerant circuit, which presents a problem that the construction of the refrigeration system becomes complex.
  • the freezer heat exchanger is defrosted by using the chiller heat exchanger as a heat source, so it is necessary to bring the chiller heat exchanger and the freezer heat exchanger into a good balance between heat absorption and heat dissipation at the time of the defrosting operation.
  • the chiller heat exchanger and the freezer heat exchanger are defrosted by using the chiller heat exchanger as a heat source, so it is necessary to bring the chiller heat exchanger and the freezer heat exchanger into a good balance between heat absorption and heat dissipation at the time of the defrosting operation.
  • the present invention has been made in view of these problems.
  • the object of the present invention is to provide a refrigeration system capable of responding to a variety of patterns of defrosting operations without providing a defrosting mechanism except for a refrigerant circuit and of preventing the action of defrosting a refrigeration heat exchanger such as a chiller heat exchanger and a freezer heat exchanger from imposing a restriction on the design of these heat exchangers.
  • a first aspect of the invention is predicated on a refrigeration system having a refrigerant circuit 20 that is constructed in such a way that a plurality of lines of refrigeration circuits 70 , 80 having refrigeration heat exchangers 72 , 84 respectively are connected to an outdoor circuit 30 provided with an outdoor heat exchanger 32 and a compression mechanism 31 and conducts a vapor compression type refrigeration cycle, at least one of the lines of refrigeration circuits 80 having an auxiliary compressor 85 connected in series to the refrigeration heat exchanger 84 .
  • This refrigeration system is characterized by including: a hot gas introduction passage 46 , 89 , 100 , 102 for selectively introducing gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into at least one of the plurality of refrigeration heat exchangers 72 , 84 ; and a defrosting path 25 capable of performing a defrosting operation of conducting a refrigeration cycle by using that refrigeration heat exchanger 72 , 84 as a condenser.
  • high-temperature refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 is introduced into at least one of the plurality of refrigeration heat exchangers 72 , 84 via the hot gas introduction passage 46 , 89 , 100 , 102 and the operation of a refrigeration cycle using that refrigeration heat exchanger 72 , 84 as a condenser is performed.
  • frost adhering to that refrigeration heat exchanger 72 , 84 is melted by heat absorbed by the heat exchanger used as an evaporator at that time and by heat produced by compressing the refrigerant in the compression mechanism 31 .
  • This defrosting operation can be performed by selecting the refrigeration heat exchanger 72 , 84 because the hot gas introduction passage 46 , 89 , 100 , 102 is provided.
  • a second aspect of the invention is characterized in that in the first aspect of the invention, the outdoor circuit 30 has a first refrigeration circuit 70 and a second refrigeration circuit 80 connected thereto in parallel, the first refrigeration circuit 70 having a first refrigeration heat exchanger 72 , the second refrigeration circuit 80 having a second refrigeration heat exchanger 84 and the auxiliary compressor 85 .
  • the first refrigeration circuit 70 can be made a chiller circuit for chilling a chiller or a chiller showcase.
  • the second refrigeration circuit 80 can be made a freezer circuit for freezing a freezer or a freezer showcase, for example.
  • the defrosting operation can be performed by a refrigeration cycle using at least one of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 as a condenser.
  • the operation of defrosting only one of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 can be performed or the operation of defrosting both of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 at the same time can be performed.
  • a third aspect of the invention is characterized in that in the first aspect of the invention, the outdoor circuit 30 has a plurality of refrigeration circuits 80 connected thereto in parallel, each of the plurality of refrigeration circuits 80 having the refrigeration heat exchanger 84 and the auxiliary compressor 85 .
  • This refrigeration circuit can be made a freezer circuit for freezing a freezer or a freezer showcase, for example.
  • the defrosting operation can be performed by a refrigeration cycle using at least one of the plural refrigeration heat exchangers 84 as a condenser.
  • the operation of defrosting only one of the refrigeration heat exchangers 84 can be performed or the operation of defrosting both of the refrigeration heat exchangers 84 at the same time can be performed.
  • a fourth aspect of the invention is characterized in: that in any one of the first aspect of the invention to the third aspect of the invention, the outdoor circuit 30 has an air heat exchanger circuit (e.g., air-conditioning circuit) 60 connected thereto, the air heat exchanger circuit 60 having an air heat exchanger (e.g., air-conditioning heat exchanger) 62 for adjusting temperature of air; and that a first defrosting operation and a second defrosting operation can be performed, the first defrosting operation using the refrigeration heat exchangers 72 , 84 as condensers and using the air heat exchanger 62 as an evaporator, the second defrosting operation using the refrigeration heat exchangers 72 , 84 as condensers and using the outdoor heat exchanger 32 as an evaporator.
  • an air heat exchanger circuit e.g., air-conditioning circuit
  • the outdoor circuit 30 has an air heat exchanger circuit (e.g., air-conditioning circuit) 60 connected thereto, the air heat exchanger circuit 60 having an air heat exchanger
  • a defrosting operation can be performed by a refrigeration cycle using at least one of the plural refrigeration heat exchangers 72 , 84 as a condenser.
  • the first defrosting operation using at least one of the plural refrigeration heat exchangers 72 , 84 as a condenser and using the air heat exchanger 62 as an evaporator and the second defrosting operation using at least one of the refrigeration heat exchangers 72 , 84 as a condenser and using the outdoor heat exchanger 32 as an evaporator can be performed.
  • a fifth aspect of the invention is characterized in that in any one of the first aspect of the invention to the fourth aspect of the invention, the hot gas introduction passage 46 , 89 has a high stage side hot gas passage 46 and a low stage hot gas passage 89 , the high stage side hot gas passage 46 being connected to a discharge line 45 of the compression mechanism 31 of the outdoor circuit 30 and to a base pipe 42 of a low-pressure gas line of the respective refrigeration circuits 70 , 80 and allowing a refrigerant flow to the respective refrigeration heat exchangers 72 , 84 from the discharge line 45 of the compression mechanism 31 at the time of a defrosting operation, the low stage side hot gas passage 89 being connected to a discharge line 22 b and a suction line 88 of the auxiliary compressor 85 and allowing a refrigerant flow to the refrigeration heat exchanger 84 connected to the auxiliary compressor 85 from the discharge line 22 b of the auxiliary compressor 85 at the time of the defrosting operation.
  • gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 first, flows through the base pipe 42 of the low-pressure gas line of the respective refrigeration circuits 70 , 80 from high stage side hot gas passage 46 to the respective refrigeration heat exchangers 72 , 84 . Then, for example, in a first refrigeration circuit (for example, chiller circuit) 70 not provided with the auxiliary compressor 85 , the discharged gas refrigerant flows into a first refrigeration heat exchanger (for example, chiller heat exchanger) 72 and the refrigeration heat exchanger 72 functions as a condenser.
  • a first refrigeration circuit for example, chiller circuit
  • the refrigeration heat exchanger 72 functions as a condenser.
  • a second refrigeration circuit for example, freezer circuit
  • the discharged gas refrigerant flows through the low stage side hot gas passage 89 and flows into a second refrigeration heat exchanger (for example, freezer heat exchanger) 84 and the refrigeration heat exchanger 84 functions as a condenser.
  • a second refrigeration heat exchanger for example, freezer heat exchanger
  • frost adhering to at least one of the refrigeration heat exchangers 72 , 84 is melted.
  • the operation of defrosting only one of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 can be performed or the operation of defrosting both of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 at the same time can be performed.
  • the operation of defrosting only one of the refrigeration heat exchangers 84 can be performed or the operation of defrosting both of the refrigeration heat exchangers 84 at the same time can be performed.
  • the refrigeration heat exchanger 84 having the auxiliary heat exchanger 85 connected thereto by stopping introducing the discharged gas refrigerant through the low stage side hot gas passage 89 , there can be brought about a state in which the defrosting operation is not performed.
  • a sixth aspect of the invention is characterized in: that in the fifth aspect of the invention, the compression mechanism 31 of the outdoor circuit 30 includes: a first compressor 31 a , a second compressor 31 b , and a third compressor 31 c , which are connected in parallel; a four-way switching valve 37 connected to an suction side of the compression mechanism 31 ; a high stage side opening/opening valve SV 1 disposed in the high stage side hot gas passage 46 ; and a low stage side opening/opening valve SV 2 disposed in the low stage side hot gas passage 89 , the first compressor 31 a having its suction pipe 41 a connected to a first port P 1 of the four-way switching valve 37 via a check valve CV 1 for prohibiting a refrigerant flow to the first compressor 31 a , the second compressor 31 b having its suction pipe 41 b connected to a second port P 2 of the four-way switching valve 37 , the third compressor 31 c having its suction pipe 41 c connected to a third port P 3 of the four-
  • the four-way switching valve 37 is set to the second state and the high stage side opening/opening valve SV 1 and the low stage side opening/opening valve SV 2 are opened and two or one of the second compressor 31 b and the third compressor 31 c of the compression mechanism 31 is actuated.
  • the gas refrigerant discharged from the compression mechanism 31 passes first from the high stage side hot gas passage 46 through the base pipe 42 of the low pressure line of the respective refrigeration circuits 70 , 80 to the respective refrigeration heat exchangers 72 , 84 .
  • the discharged gas refrigerant flows into the first refrigeration heat exchangers (for example, chiller heat exchanger) 72 and the heat exchanger 72 functions as a condenser.
  • the second refrigeration circuit (for example, freezer circuit) 80 provided with the auxiliary compressor 85 the discharged gas refrigerant flows through the low stage side hot gas passage 89 and flows into the second refrigeration heat exchanger (for example, freezer heat exchanger) 84 and the heat exchanger 84 functions as a condenser.
  • frost adhering to at least one of the respective refrigeration heat exchangers 72 , 84 is melted.
  • the operation of defrosting only one of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 can be performed or the operation of defrosting both of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 at the time can be performed.
  • the operation of defrosting only one of the first refrigeration heat exchangers 84 can be performed or the operation of defrosting both of the refrigeration heat exchangers 84 at the time can be performed.
  • the refrigeration heat exchanger 84 having the auxiliary compressor 85 connected thereto by closing the low stage side opening/opening valve SV 2 to stop introducing the discharged gas refrigerant through the low stage side hot gas passage 89 , there can be brought about a state in which the defrosting operation is not performed.
  • the low-pressure gas refrigerant having finished an expansion process and an evaporation process after a condensation process in the refrigeration heat exchangers 72 , 84 passes through the four-way switching valve 37 , the suction pipe 41 b , and the suction pipe 41 c and then is sucked by the second compressor 32 b and the third compressor 31 c.
  • a seventh aspect of the invention is characterized in: that in the fifth aspect of the invention, the compression mechanism 31 of the outdoor circuit 30 includes: a first compressor 31 a , a second compressor 31 b , and a third compressor 31 c , which are connected in parallel; a four-way switching valve 37 connected to a suction side of the compression mechanism 31 ; and a low stage side opening/closing valve SV 2 disposed in the low stage side hot gas passage 89 , the first compressor 31 a having its suction pipe 41 a connected to a first port P 1 of the four-way switching valve 37 , the second compressor 31 b having its suction pipe 41 b connected to a second port P 2 of the four-way switching valve 37 , the third compressor 31 c having its suction pipe 41 c connected to a third port P 3 of the four-way switching valve 37 via a check valve CV 2 for prohibiting a refrigerant flow to the third compressor 31 c ; that the high stage side hot gas passage 46 is connected to a fourth port P 4
  • the four-way switching valve 37 is set to the second state and the low stage side opening/closing valve SV 2 is opened and two or one of the second compressor 31 b and the third compressor 31 c of the compression mechanism 31 is actuated.
  • the gas refrigerant discharged from the compression mechanism 31 passes first from the high stage side hot gas passage 46 and the four-way switching valve 37 through the base pipe 42 of the low pressure line of the respective refrigeration circuits 70 , 80 to the respective refrigeration heat exchangers 72 , 84 .
  • the discharged gas refrigerant flows into the first refrigeration heat exchanger (for example, chiller heat exchanger) 72 and the heat exchanger 72 functions as a condenser.
  • the second refrigeration circuit (for example, freezer circuit) 80 provided with the auxiliary compressor 85 the discharged gas refrigerant flows through the low stage side hot gas passage 89 and flows into the second refrigeration heat exchanger (for example, freezer heat exchanger) 84 and the heat exchanger 84 functions as a condenser.
  • frost adhering to at least one of the respective refrigeration heat exchangers 72 , 84 is melted.
  • the operation of defrosting only one of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 can be performed or the operation of defrosting both of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 at the same time can be performed.
  • the operation of defrosting only one of the refrigeration heat exchangers 84 can be performed or the operation of defrosting both of the refrigeration heat exchangers 84 at the same time can be performed.
  • the refrigeration heat exchanger 84 having the auxiliary compressor 85 connected thereto by closing the low stage side opening/closing valve SV 2 to stop introducing the discharged gas refrigerant through the low stage side hot gas passage 89 , there can be brought about a state in which the defrosting operation is not performed.
  • the low-pressure gas refrigerant having finished an expansion process and an evaporation process after a condensation process in the refrigeration heat exchangers 72 , 84 passes through the four-way switching valve 37 , the suction pipe 41 b , and the suction pipe 41 c and then is sucked by the second compressor 32 b and the third compressor 31 c.
  • An eighth aspect of the invention is characterized in that in the first aspect of the invention, the hot gas passage 46 , 89 includes a first introduction passage 96 and a second introduction passage 97 , the first introduction passage 96 introducing gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into the auxiliary compressor 85 , the second introduction passage 97 introducing gas refrigerant discharged from the auxiliary compressor 85 into the refrigeration heat exchanger 84 .
  • the gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 is introduced into the auxiliary compressor 85 via the first introduction passage 96 and is compressed by the auxiliary compressor 85 and then the gas refrigerant discharged from the auxiliary compressor 85 is introduced into the refrigeration heat exchanger 84 via the second introduction passage 97 and is used for defrosting the refrigeration heat exchanger 84 .
  • the refrigerant is compressed by both of the compression mechanism 31 of the outdoor circuit 30 and the auxiliary compressor 85 , so heat given to the refrigerant at the time of the defrosting operation can be increased.
  • a ninth aspect of the invention is characterized in: that in the eighth aspect of the invention, the second introduction passage 97 is connected to the compression mechanism 31 of the outdoor circuit 30 and to the refrigeration heat exchanger 84 ; that the first introduction passage 96 is branched from the second introduction passage 97 and is connected to the auxiliary compressor 85 so as to introduce part of gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into the auxiliary compressor 85 ; and that the second introduction passage 97 has a discharge pipe 98 of the auxiliary compressor 85 connected to its portion closer to the compression mechanism 31 of the outdoor circuit 30 .
  • part of the gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 is introduced into the auxiliary compressor 85 via the first introduction passage 96 and is further compressed by the auxiliary compressor 85 . Then, the gas refrigerant discharged from the auxiliary compressor 85 is merged with the gas refrigerant discharged from the compression mechanism 31 and flowing through the second introduction passage 97 and the refrigerant after merging is introduced into the refrigeration heat exchanger 84 and is used for defrosting the refrigeration heat exchanger 84 .
  • the refrigerant is compressed by both of the compression mechanism 31 of the outdoor circuit 30 and the auxiliary compressor 85 , so heat given to the refrigerant at the time of the defrosting operation can be increased.
  • a tenth aspect of the invention is characterized in that the ninth aspect of the invention, there is provided a liquid injection passage 99 for introducing part of liquid refrigerant flowing out of the refrigeration heat exchanger 84 into the auxiliary compressor 85 .
  • this tenth aspect of the invention is performed a liquid injecting operation for supplying the auxiliary compressor 85 with part of the refrigerant condensed by the refrigeration heat exchanger 84 and brought into a liquid state in the ninth aspect of the invention.
  • the refrigerant sucked by the auxiliary compressor 85 is refrigerated. For this reason, it is possible to prevent the temperature of the gas refrigerant discharged from the auxiliary compressor 85 from being increased excessively as compared with a case where the liquid injecting operation is not performed.
  • An eleventh aspect of the invention is characterized in that in the ninth aspect of the invention, the auxiliary compressor 85 is constructed of a variable displacement compressor.
  • the temperature of the gas refrigerant discharged from the auxiliary compressor 85 is easily increased.
  • the control of lowering an operating capacity is performed to prevent the temperature of the gas refrigerant discharged from the auxiliary compressor 85 from being excessively increased.
  • a twelfth aspect of the invention is characterized in that in the first aspect of the invention, the hot gas introduction passage 100 , 102 is directly connected to a discharge line 45 of the compression mechanism 31 of the outdoor circuit 30 and to at least one of gas side piping 110 , 112 of the refrigeration heat exchangers 72 , 84 .
  • the high-temperature gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 is introduced into at least one of the refrigeration heat exchangers 72 , 84 from the gas side.
  • the defrosting operation can be performed by using this refrigeration heat exchanger 72 , 84 as a condenser and by using the other refrigeration heat exchanger as an evaporator.
  • a thirteenth aspect of the invention is characterized in that in the twelfth aspect of the invention, the hot gas introduction passage 100 , 102 is connected to a discharge line 45 of the compression mechanism 31 of the outdoor circuit 30 and to gas side piping 110 , 112 of the plurality of refrigeration heat exchangers 72 , 84 and is provided with a switching mechanism 103 capable of switching or selecting the plurality of refrigeration heat exchangers 72 , 84 .
  • the defrosting operation can be performed by switching or selecting the plurality of refrigeration heat exchangers 72 , 84 .
  • a fourteenth aspect of the invention is characterized in that in the twelfth aspect of the invention or the thirteenth aspect of the invention, the hot gas introduction passage 100 , 102 is provided with a flow control mechanism 101 .
  • the flow of the high-temperature gas refrigerant flowing through the hot gas introduction passage 100 , 102 can be controlled.
  • the hot gas introduction passage 46 , 89 , 100 , 102 for selectively introducing the gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into at least one of the plurality of refrigeration heat exchangers 72 , 84 and the defrosting operation by the refrigeration cycle using the refrigeration heat exchanger 72 , 84 as the condenser can be performed.
  • the refrigeration heat exchangers 72 , 84 can be defrosted by the use of heat absorbed by the outdoor heat exchanger 32 and heat produced by compressing the refrigerant by the compression mechanism 31 . Further, when the refrigeration system is provided with an air-conditioning circuit, the refrigeration heat exchangers 72 , 84 can be defrosted by the use of heat absorbed by the air-conditioning heat exchanger 62 at the time of the cooling operation and heat produced by compressing the refrigerant by the compression mechanism 31 .
  • the refrigeration system can perform a variety of patterns of defrosting operations.
  • a dedicated defrosting mechanism such as an electric heater in addition to the refrigerant circuit 20
  • the refrigeration system can perform a variety of patterns of defrosting operations.
  • a refrigeration system in the related art in which a freezer heat exchanger is defrosted by using a chiller heat exchanger as a heat source, in this refrigeration system, it is not always necessary to bring the plural refrigeration heat exchangers 72 , 84 into a good balance between heat absorption and heat dissipation at the time of the defrosting operation, so it is possible to enhance the degree of flexibility in designing the refrigeration system.
  • the first refrigeration circuit 70 and the second refrigeration circuit 80 are connected in parallel to the outdoor circuit 30 , the first refrigeration circuit 70 having the first refrigeration heat exchanger 72 , the second refrigeration circuit 80 having the second refrigeration heat exchanger 84 and an auxiliary compressor 85 .
  • the operation of defrosting only one of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 can be performed or the operation of defrosting both of the first refrigeration heat exchanger 72 and the second refrigeration heat exchanger 84 at the same time can be performed. For this reason, it is possible to perform a variety of patterns of defrosting operations.
  • the plurality of refrigeration circuits 80 each having a refrigeration heat exchanger 84 and an auxiliary compressor 85 are connected in parallel to the outdoor circuit 30 in the refrigeration circuit, so for example, when there are provided two refrigeration heat exchangers 84 , the operation of defrosting only one of the refrigeration heat exchangers 84 can be performed or the operation of defrosting both of the refrigeration heat exchangers 84 at the same time can be performed.
  • the plurality of refrigeration circuits 70 , 80 and the air heat exchange circuit 60 are connected to the outdoor circuit 30 , and the first defrosting operation using at least one of the plurality of refrigeration heat exchangers 72 , 84 as a condenser and using the air heat exchanger 62 as an evaporator and the second defrosting operation using at least one of the refrigeration heat exchangers 72 , 84 as a condenser and using the outdoor heat exchanger 32 as an evaporator can be performed.
  • the first defrosting operation using at least one of the plurality of refrigeration heat exchangers 72 , 84 as a condenser and using the air heat exchanger 62 as an evaporator can be performed.
  • the second defrosting operation using at least one of the refrigeration heat exchangers 72 , 84 as a condenser and using the outdoor heat exchanger 32 as an evaporator can be performed.
  • the hot gas introduction passage 46 , 89 is constructed of the high stage side hot gas passage 46 and the low stage hot gas passage 89 , the high stage side hot gas passage 46 allowing a refrigerant flow to the respective refrigeration heat exchangers 72 , 84 from the discharge line 45 of the compression mechanism 31 at the time of the defrosting operation, the low stage side hot gas passage 89 allowing a refrigerant flow to the refrigeration heat exchanger 84 connected to the auxiliary compressor 85 from the discharge line 22 b of the auxiliary compressor 85 at the time of the defrosting operation.
  • the operation of selectively introducing the gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into the respective refrigeration heat exchangers 72 , 84 at the time of the defrosting operation can be performed with reliability.
  • by selectively introducing the gas refrigerant discharged from the compression mechanism 31 into the respective refrigeration heat exchangers 72 , 84 from the high stage side hot gas passage 46 and the low stage hot gas passage 89 it is possible to respond to a variety of patterns of defrosting operations.
  • the refrigerant circuit 20 using three compressors 31 a , 31 b , 31 c as the compression mechanism 31 of the outdoor circuit 30 and using the four-way switching valve 37 on the suction side and having the plurality of refrigeration heat exchangers 72 , 84 , it is possible to respond to a variety of patterns of defrosting operations without making the construction of the refrigerant circuit 20 complex.
  • the seventh aspect of the invention just as with the sixth aspect of the invention, in the refrigerant circuit 20 using three compressors 31 a , 31 b , 31 c as the compression mechanism 31 of the outdoor circuit 30 and using the four-way switching valve 37 on the suction side and having the plurality of refrigeration heat exchangers 72 , 84 , it is possible to respond to a variety of patterns of defrosting operations without making the construction of the refrigerant circuit 20 complex.
  • heat given to the refrigerant at the time of the defrosting operation can be increased, so the defrosting capacity of the refrigeration heat exchanger 84 can be increased.
  • the refrigeration heat exchanger 84 can be effectively defrosted.
  • heat given to the refrigerant at the time of the defrosting operation can be increased, so the defrosting capacity of the refrigeration heat exchanger 84 can be increased.
  • the defrosting capacity is not sufficient, by performing the control of the present invention, the refrigeration heat exchanger 84 can be effectively defrosted.
  • the tenth aspect of the invention by performing the liquid injecting operation at the time of defrosting operation in the ninth aspect of the invention, it is possible to avoid the temperature of the gas refrigerant discharged from the auxiliary compressor 85 from being abnormally increased and hence to protect the auxiliary compressor 85 with reliability.
  • the eleventh aspect of the invention by decreasing the operating capacity of the auxiliary compressor 85 at the time of the defrosting operation in the ninth aspect of the invention, it is possible to avoid the temperature of the gas refrigerant discharged from the auxiliary compressor 85 from being abnormally increased and hence to protect the auxiliary compressor 85 with reliability.
  • the hot gas introduction passage 100 , 102 is directly connected to the discharge line 45 of the compression mechanism 31 of the outdoor circuit 30 and to at least one of the gas side piping 110 , 112 of the refrigeration heat exchangers 72 , 84 .
  • the high-temperature gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 is introduced into at least one of the refrigeration heat exchangers 72 , 84 from the gas side.
  • the defrosting operation can be performed by using this refrigeration heat exchanger 72 , 84 as a condenser and by using the other refrigeration heat exchanger as an evaporator.
  • the hot gas introduction passage 100 , 102 is connected to the discharge line 45 of the compression mechanism 31 of the outdoor circuit 30 and to the gas side piping 110 , 112 of the plurality of refrigeration heat exchangers 72 , 84 and is provided with the switching mechanism 103 capable of switching or selecting the plurality of refrigeration heat exchangers 72 , 84 .
  • the defrosting operation can be performed by switching or selecting the plurality of refrigeration heat exchangers 72 , 84 .
  • the hot gas introduction passage 100 , 102 is provided with the flow control mechanism 101 , so the flow of the high-temperature gas refrigerant flowing through the hot gas introduction passage 100 , 102 can be controlled.
  • frost adhering to the refrigeration heat exchangers 72 , 84 is melted at a stretch and hence the block of the frost around the refrigeration heat exchangers 72 , 84 might be dropped.
  • the frost can be gradually melted and hence it is possible to prevent the block of the frost from being dropped.
  • FIG. 1 is a refrigerant circuit diagram of a refrigeration system according to an embodiment 1.
  • FIG. 2 is a refrigerant circuit diagram showing an operation at the time of a cooling operation in the embodiment 1.
  • FIG. 3 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of the cooling operation in the embodiment 1.
  • FIG. 4 is a refrigerant circuit diagram showing another example of the defrosting operation at the time of the cooling operation in the embodiment 1.
  • FIG. 5 is a refrigerant circuit diagram showing an operation at the time of a heating operation in the embodiment 1.
  • FIG. 6 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of the heating operation in the embodiment 1.
  • FIG. 7 is a refrigerant circuit diagram showing another example of the defrosting operation at the time of the heating operation in the embodiment 1.
  • FIG. 8 is a refrigerant circuit diagram of a refrigeration system according to an embodiment 2.
  • FIG. 9 is a refrigerant circuit diagram showing an operation at the time of a cooling operation in the embodiment 2.
  • FIG. 10 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of the cooling operation in the embodiment 2.
  • FIG. 11 is a refrigerant circuit diagram showing another example of the defrosting operation at the time of the cooling operation in the embodiment 2.
  • FIG. 12 is a refrigerant circuit diagram showing an operation at the time of a heating operation in the embodiment 2.
  • FIG. 13 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of the heating operation in the embodiment 2.
  • FIG. 14 is a refrigerant circuit diagram showing another example of the defrosting operation at the time of the heating operation in the embodiment 2.
  • FIG. 15 is a refrigerant circuit diagram of a refrigeration system according to an embodiment 3.
  • FIG. 16 is a refrigerant circuit diagram showing an operation at the time of a cooling operation in the embodiment 3.
  • FIG. 17 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of the cooling operation in the embodiment 3.
  • FIG. 18 is a refrigerant circuit diagram showing another example of the defrosting operation at the time of the cooling operation in the embodiment 3.
  • FIG. 19 is a refrigerant circuit diagram showing an operation at the time of a heating operation in the embodiment 3.
  • FIG. 20 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of the heating operation in the embodiment 3.
  • FIG. 21 is a refrigerant circuit diagram showing another example of the defrosting operation at the time of the heating operation in the embodiment 3.
  • FIG. 22 is a refrigerant circuit diagram showing an example of a defrosting operation at the time of a cooling operation in an embodiment 4.
  • FIG. 23 is a refrigerant circuit diagram of a refrigeration system according to an embodiment 5.
  • a refrigeration system 10 of this embodiment is installed in a convenience store or the like and air-conditions the store and refrigerates the interior of a showcase.
  • the refrigeration system 10 of this embodiment has an outdoor unit 11 , an air-conditioning unit 12 , a chiller showcase 13 as a chiller unit, a freezer showcase 14 as a freezer unit.
  • the outdoor unit 11 is installed outdoors.
  • all of the air-conditioning unit 12 , the chiller showcase 13 , and the freezer showcase 14 are installed in the convenience store or the like.
  • the outdoor unit 11 is provided with an outdoor circuit 30 .
  • the air-conditioning unit 11 is provided with an air-conditioning circuit (air heat exchanger circuit) 60 .
  • the chiller showcase 13 is provided with a chiller circuit (first refrigeration circuit) 70 .
  • the freezer showcase 14 is provided with a freezer circuit (second refrigeration circuit) 80 .
  • these circuits 30 , 60 , 70 , and 80 are connected by piping to construct a refrigerant circuit 20 .
  • the refrigerant circuit 20 includes a chiller/freezer circuit and an air-conditioning circuit.
  • the chiller circuit 70 and the freezer circuit 80 both of which are the refrigeration circuits are connected in parallel to the outdoor circuit 30 .
  • the chiller circuit 70 and the freezer circuit 80 are connected to the outdoor circuit 30 via first liquid side connection piping 21 and first gas side connection piping 22 .
  • the first liquid side connection piping 21 has its one end connected to the outdoor circuit 20 .
  • the first liquid side connection piping 21 has its other end branched into two parts and has one (chiller side branch liquid pipe 21 a ) of the branched parts connected to the liquid side end of the chiller circuit 70 and has the other (freezer side branch liquid pipe 21 b ) of the branched parts connected to the liquid side end of the freezer circuit 80 .
  • the first gas side connection piping 22 has its one end connected to the outdoor circuit 30 .
  • the first gas side connection piping 22 has its other end branched into two parts and has one (chiller side branch gas pipe 22 a ) of the branched parts connected to the gas side end of the chiller circuit 70 and has the other (freezer side branch gas pipe 22 b ) of the branched parts connected to the gas side end of the freezer circuit 80 .
  • the air-conditioning circuit 60 is connected to the outdoor circuit 30 via second liquid side connection piping 23 branched from the first liquid side connection piping 21 and second gas side connection piping 24 .
  • the second liquid side connection piping 23 has its one end connected to the outdoor circuit 30 via the first liquid side connection piping 21 and has its other end connected to the liquid side end of the air-conditioning circuit 60 .
  • the second gas side connection piping 24 has its one end connected to the outdoor circuit 30 and has its other end connected to the gas side end of the air-conditioning circuit 60 .
  • the outdoor unit 11 is provided with the outdoor circuit 30 .
  • the outdoor circuit 30 is provided with a compression mechanism 31 , an outdoor heat exchanger 32 , a receiver 33 , and an outdoor expansion valve 34 .
  • the outdoor circuit 30 is provided with a first four-way switching valve 35 , a second four-way switching valve 36 , a third four-way switching valve 37 , a liquid side stop valve 38 , a first gas side stop valve 39 a , and a second gas side stop valve 39 b .
  • the liquid side stop valve 38 has the first liquid side connection piping 21 connected thereto and the first gas side stop valve 39 a has the first gas side connection piping 22 connected thereto and the second gas side stop valve 39 b has the second gas side connection piping 24 connected thereto.
  • the compression mechanism 31 is constructed of a DC inverter compressor 31 a of a first compressor, a first non-inverter compressor 31 b of a second compressor, and a second non-inverter compressor 31 c of a third compressor, which are connected in parallel to each other.
  • the respective compressors 31 a , 31 b , and 31 c are scroll compressors of a hermetic high-pressure dome type, respectively.
  • the DC inverter compressor 31 a is supplied with electric power via an inverter. By changing the output frequency of the inverter of the DC inverter compressor 31 a to change the rotation speed of its electric motor, the operation capacity of the DC inverter compressor 31 a can be adjusted.
  • the first non-inverter compressor 31 b and the second non-inverter compressor 31 c have their electric motors driven always at their specified rotation speeds and hence have their operation capacities kept constant.
  • the DC inverter compressor 31 a has one end of a first suction pipe 41 a connected to its suction side.
  • the first non-inverter compressor 31 b has one end of a second suction pipe 41 b connected to its suction side.
  • the second non-inverter compressor 31 c has one end of a third suction pipe 41 c connected to its suction side.
  • the other end of the first suction pipe 41 a is connected to a first low-pressure gas pipe 42 of the base pipe of a chiller/freezer line low-pressure gas line and a first communication pipe 43 a and the first low-pressure gas pipe 42 is connected to the first gas side stop valve 39 a .
  • the first suction pipe 41 a is connected to a first port P 1 of the third four-way switching valve 37 via the first communication pipe 43 a .
  • the first communication pipe 43 a is provided with a check valve CV 1 for prohibiting a refrigerant flow to the DC inverter compressor 31 a .
  • the other end of the second suction pipe 41 a is connected to a second port P 2 of the third four-way switching valve 37 .
  • the other end of the third suction pipe 41 c is connected to a second low-pressure gas pipe 44 and a second communication pipe 43 b and the second low-pressure gas pipe 44 is connected to a second four-way switching valve 36 .
  • the third suction pipe 41 c is connected to a third port P 3 of the third four-way switching valve 37 via the second communication pipe 43 b .
  • the second communication pipe 43 b is provided with a check valve CV 2 for prohibiting a refrigerant flow to the second non-inverter compressor 31 c.
  • the compression mechanism 31 has a high-pressure gas pipe (discharge line) 45 connected to its discharge side.
  • the high-pressure gas pipe 45 has one end of a high stage side hot gas passage 46 connected thereto and the other end of the high stage side hot gas passage 46 is connected to the first suction pipe 41 a .
  • the high stage side hot gas passage 46 has a first solenoid valve SV 1 as a high stage side opening/opening valve.
  • the high stage side hot gas passage 46 is a passage which is connected to the discharge line 45 of the compression mechanism 31 of the outdoor circuit 30 and to the first low-pressure gas pipe 42 of the base pipe of the low-pressure gas line of the respective refrigeration circuits 70 , 80 and allows a refrigerant flow to the respective refrigeration heat exchangers 72 , 84 from the discharge line 45 of the compression mechanism 31 at the time of the defrosting operation.
  • the high stage side hot gas passage 46 has one end of a high-pressure introduction pipe 47 connected between the discharge side of the compression mechanism 31 and the first solenoid valve SV 1 .
  • the high-pressure introduction pipe 47 communicates with the high pressure line of the compression mechanism 31 via the high stage side hot gas passage 46 and has its other end connected to a fourth port P 4 of the third four-way switching valve 37 .
  • This third four-way switching valve 37 can switch between a first state (state shown by a solid line in FIG. 1 ) in which the first port P 1 and the second port P 2 communicate with each other and in which the third port P 3 and the fourth port P 4 communicate with each other and a second state (state shown by a broken line in FIG. 1 ) in which the first port P 1 and the fourth port P 4 communicate with each other and in which the second port P 2 and the third port P 3 communicate with each other.
  • the DC inverter compressor 31 a has a first discharge pipe 48 a connected to its discharge side and the first non-inverter compressor 31 b has a second discharge pipe 48 b connected to its discharge side and the second non-inverter compressor 31 c has a third discharge pipe 48 c connected to its discharge side.
  • the first discharge pipe 48 a is provided with a check valve CV 3 for prohibiting a refrigerant flow to the DC inverter compressor 31 a and the second discharge pipe 48 b is provided with a check valve CV 4 for prohibiting a refrigerant flow to the first non-inverter compressor 31 b and the third discharge pipe 48 c is provided with a check valve CV 5 for prohibiting a refrigerant flow to the second non-inverter compressor 31 c .
  • the first discharge pipe 48 a , the second discharge pipe 48 b , and the third discharge pipe 48 c are merged with each other and connected to the high-pressure gas pipe 45 .
  • the third discharge pipe 48 c has a discharge connection pipe 49 connected between the point where the third discharge pipe 48 c is connected to the high pressure pipe 45 and the check valve CV 5 .
  • the first port P 1 is connected to the high-pressure gas pipe 45 and the second port P 2 is connected to the outdoor heat exchanger 32 via a first gas pipe 50 and the third port P 3 is connected to the second four-way switching valve 36 via a gas connection pipe 52 and the fourth port P 4 is connected to the second gas side stop valve 39 b via a second gas pipe 51 .
  • the first four-way switching valve 35 can switch between a first state (state shown by a solid line in FIG. 1 ) in which the first port P 1 and the second port P 2 communicate with each other and in which the third port P 3 and the fourth port P 4 communicate with each other and a second state (state shown by a broken line in FIG. 1 ) in which the first port P 1 and the fourth port P 4 communicate with each other and in which the second port P 2 and the third port P 3 communicate with each other.
  • the first port P 1 is connected to the discharge connection pipe 49 and the third port P 3 is connected to the second low-pressure gas pipe 44 and the fourth port P 4 is connected to the gas connection pipe 52 .
  • the second four-way switching valve 36 has its second port P 2 closed.
  • This second four-way switching valve 36 can switch between a first state (state shown by a solid line in FIG. 1 ) in which the first port P 1 and the second port P 2 communicate with each other and in which the third port P 3 and the fourth port P 4 communicate with each other and a second state (state shown by a broken line in FIG. 1 ) in which the first port P 1 and the fourth port P 4 communicate with each other and in which the second port P 2 and the third port P 3 communicate with each other.
  • the outdoor heat exchanger 32 is a fin-and-tube heat exchanger of a cross fin type and constructs a heat source side heat exchanger.
  • An outdoor fan 32 a is disposed near the outdoor heat exchanger 32 .
  • Outdoor air is sent to the outdoor heat exchanger 32 by the outdoor fan 32 a and heat is exchanged between the refrigerant and the outdoor air in the outdoor heat exchanger 32 .
  • the outdoor heat exchanger 32 as described above, has its one end connected to the first four-way switching valve 35 .
  • the outdoor heat exchanger 32 has its other end connected to the top of a receiver 33 via a first liquid pipe 53 .
  • the first liquid pipe 53 is provided with a check valve CV 6 that allows a refrigerant flow to the receiver 33 from the outdoor heat exchanger 32 and prohibits a back flow.
  • the receiver 33 has one end of a second liquid pipe 54 connected to its bottom.
  • the second liquid pipe 54 has its other end connected to a liquid side stop valve 38 .
  • the second liquid pipe 54 is provided with a check valve CV 7 that allows a refrigerant flow to a liquid side stop valve 38 from the receiver 33 and prohibits a back flow.
  • a third liquid pipe 55 is connected between the check valve CV 7 and the liquid side stop valve 38 .
  • the other end of the third liquid pipe 55 is connected to the top of the receiver 33 .
  • the third liquid pipe 55 is provided with a check valve CV 8 that allows a refrigerant flow to the receiver 33 from the liquid side stop valve 38 and prohibits a back flow.
  • a fourth liquid pipe 56 is connected between the receiver 33 and the check valve CV 7 in the second liquid pipe 54 .
  • the other end of the fourth liquid pipe 56 is connected between the outdoor heat exchanger 32 and check valve CV 6 in the first liquid pipe 53 .
  • the fourth liquid pipe 56 is provided with an outdoor expansion valve 34 .
  • the outdoor circuit 30 is provided with also various sensors and pressure switches.
  • the high-pressure gas pipe 45 is provided with a discharge temperature sensor 57 and a discharge pressure sensor (not shown).
  • Each of the first discharge pipe 48 a and the third discharge pipe 48 c is provided with a high-pressure pressure sensor 58 .
  • each of the suction pipes 41 a , 41 b , and 41 c is provided with a suction temperature sensor and a suction pressure sensor although they are not shown.
  • an outdoor air temperature sensor 59 is disposed near the outdoor fan 32 a.
  • the air-conditioning unit 12 has an air-conditioning circuit (air heat exchange circuit) 60 .
  • an air-conditioning expansion valve 61 and an air heat exchanger 62 are disposed in this order from a liquid side end to a gas side end.
  • the air heat exchanger 62 is constructed of a fin-and-tube heat exchanger of a cross fin type. In this air heat exchanger 62 , heat is exchanged between the refrigerant and the indoor air.
  • the air-conditioning expansion valve 61 is constructed of an electronic expansion valve.
  • the air-conditioning unit 12 is provided with a heat exchanger temperature sensor 63 and a refrigerant temperature sensor 64 .
  • the heat exchanger temperature sensor 63 is disposed in a heat exchanger tube of the air heat exchanger 62 .
  • the refrigerant temperature sensor 64 is disposed near a gas side end in the air-conditioning circuit 60 .
  • the air-conditioning unit 12 is provided with an indoor air temperature sensor 65 and an air-conditioning fan 66 . Indoor air in the store is sent to the air heat exchanger 62 by the air-conditioning fan 66 .
  • the chiller showcase 13 has a chiller circuit 70 .
  • a chiller expansion valve 71 and a chiller heat exchanger (first refrigeration heat exchanger) 72 are disposed in this order from its liquid side end to a gas side end.
  • the chiller heat exchanger 72 is constructed of a fin-and-tube heat exchanger of a cross fin type. In this chiller heat exchanger 72 , heat is exchanged between the refrigerant and the air in the chiller showcase 13 .
  • the chiller expansion valve 71 is constructed of an electronic expansion valve.
  • the chiller showcase 13 is provided with a heat exchanger temperature sensor 73 and refrigerant temperature sensors 74 , 75 .
  • the heat exchanger temperature sensor 73 is disposed in a heat exchanger tube of the chiller heat exchanger 72 .
  • a gas refrigerant temperature sensor 74 is disposed near a gas side end in the chiller circuit 70 and a liquid refrigerant temperature sensor 75 is disposed near a liquid side end in the chiller circuit 70 .
  • the chiller showcase 13 is provided with a chiller temperature sensor 76 and a chiller fan 77 . Air in the chiller showcase 13 is sent to the chiller heat exchanger 72 by the chiller fan 77 .
  • the freezer showcase 14 has a freezer circuit 80 .
  • a refrigerant heat exchanger 81 In the freezer circuit 80 , a refrigerant heat exchanger 81 , a drain pan heater 82 , a freezer expansion valve 83 , a freezer heat exchanger (second refrigeration heat exchanger) 84 , and a DC inverter compressor used as a booster compressor (auxiliary compressor) 85 are disposed in this order from its liquid side end to a gas side end.
  • the freezer heat exchanger 84 is constructed of a fin-and-tube heat exchanger of a cross fin type. In this freezer heat exchanger 84 , heat is exchanged between the refrigerant and the air in the freezer showcase 14 .
  • the freezer expansion valve 83 is constructed of an electronic expansion valve.
  • the freezer expansion valve 83 is an expansion valve that is disposed in a freezer circuit 80 and can change the degree of opening.
  • the refrigerant heat exchanger 81 is a heat exchanger in which the refrigerants exchange heat between them and is constructed of a plate heat exchanger, for example.
  • This refrigerant heat exchanger 81 has a high pressure side passage 81 a connected to a freezer side branch liquid pipe 21 b and a low pressure side passage 81 b connected to a branch pipe 86 branched from the downstream side of the high pressure side passage 81 a in the freezer side branch liquid pipe 21 b .
  • the branch pipe 86 has an electronic expansion valve disposed upstream of the low pressure side passage 81 b and has the downstream side of the low pressure side passage 81 b connected to an intermediate-pressure position of the booster compressor 85 .
  • An economizer is constructed of the refrigerant heat exchanger 81 and the electronic expansion valve 87 .
  • a check valve CV 9 that allows refrigerant to be discharged from the booster compressor 85 and prohibits the back flow of the refrigerant is disposed in a freezer side branch gas pipe 22 b of the discharge line of the booster compressor 85 .
  • a low stage side hot gas passage 89 is connected between a downstream position of the check valve CV 9 in the freezer side branch gas pipe 22 b and a suction pipe 88 of the suction line of the booster compressor 85 .
  • the low stage side hot gas passage 89 is a passage, which is connected to the freezer side branch gas pipe 22 b and the suction pipe 88 and allows a refrigerant flow to the freezer heat exchanger 84 from the freezer side branch gas pipe 22 b at the time of the defrosting operation, and is provided with a second solenoid valve SV 2 of a low stage side opening/opening valve.
  • the freezer showcase 14 is provided with a heat exchanger temperature sensor 90 and refrigerant temperature sensors 91 , 92 .
  • the heat exchanger temperature sensor 90 is fixed to a heat exchanger tube of the freezer heat exchanger 84 .
  • a gas refrigerant temperature sensor 91 is disposed near a gas side end in the freezer circuit 80 .
  • a liquid refrigerant temperature sensor 92 is disposed near a liquid side end in the freezer circuit 80 .
  • a drain pan heater temperature sensor 93 is disposed near the drain pan heater 82 .
  • the freezer showcase 14 is provided with a freezer temperature sensor 94 and a freezer fan 95 . Air in the freezer showcase 14 is sent to the freezer heat exchanger 84 by the freezer fan 95 .
  • the refrigerant circuit 20 of this embodiment has the chilling/freezer line side circuit and the air-conditioning line side circuit.
  • the plural refrigeration circuits (chiller circuit 70 and freezer circuit 80 ), which have refrigeration heat exchangers 72 , 84 respectively, are connected in parallel to the outdoor circuit 30 provided with the outdoor heat exchanger 32 and the compression mechanism 31 .
  • the booster compressor 85 is connected in series to the freezer heat exchanger 84 .
  • the refrigerant circuit 20 of this embodiment has a high stage side hot gas passage 46 and a low stage side hot gas passage 89 as hot gas introduction passages 46 , 89 for selectively introducing the gas refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into at least one of the plural refrigeration heat exchangers 72 , 84 and is constructed so as to perform the defrosting operation of conducting the refrigeration cycle by using the refrigeration heat exchangers 72 , 84 as condensers.
  • the refrigerant circuit 20 includes the air-conditioning circuit 60 that has the air-conditioning heat exchanger 62 and air-conditions the room.
  • the refrigerant circuit 20 is constructed so as to perform the defrosting operation (first defrosting operation) at the time of a cooling operation in which the refrigeration heat exchangers 72 , 84 are used as condensers and in which the air-conditioning heat exchanger 62 is used an evaporator and the defrosting operation (second defrosting operation) at the time of a heating operation in which the refrigeration heat exchangers 72 , 84 are used as condensers and in which the outdoor heat exchanger 32 is used an evaporator.
  • a cooling operation is the operation of refrigerating air in the chiller showcase 13 and the freezer showcase 14 and refrigerating air in the store by the air-conditioning unit 12 to cool the interior of the store.
  • the first four-way switching valve 35 , the second four-way switching valve 36 , and the third four-way switching valve 37 are set to the first state.
  • the outdoor expansion valve 34 is totally closed, and the air-conditioning expansion valve 61 , the chiller expansion valve 71 , and the freezer expansion valve have their degrees of opening suitably adjusted, and the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valve SV 2 of the low stage side hot gas passage 89 are closed.
  • the DC inverter compressor 31 a , the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerants discharged from the DC inverter compressor 31 a , the first non-inverter compressor 31 b , and the second non-inverter compressor 31 c pass through the respective discharge pipes 48 a , 48 b , and 48 c and merge with each other in the high-pressure gas pipe 45 . Then, the refrigerant after merging passes through the first four-way switching valve 35 and is sent to the outdoor heat exchanger 32 . In the outdoor heat exchanger 32 , the refrigerant dissipates heat to the outdoor air, thereby being condensed.
  • the refrigerant condensed in the outdoor heat exchanger 32 passes through the receiver 33 and flows to the first liquid side connection piping 21 and is distributed to the chiller side branch liquid pipe 21 a , the freezer side branch liquid pipe 21 b , and the second liquid side connection piping 23 .
  • the refrigerant flowing into the chiller circuit 70 from the chiller side branch liquid pipe 21 a has its pressure reduced when the refrigerant passes the chiller expansion valve 71 and then is introduced into the chiller heat exchanger 72 .
  • the refrigerant absorbs heat from the air in the chiller showcase 13 , thereby being evaporated.
  • the evaporation temperature of the refrigerant is set to about ⁇ 5° C., for example.
  • the refrigerant evaporated in the chiller heat exchanger 72 flows through the chiller side branch gas pipe 22 a and flows into the first gas side connection piping 22 .
  • the air refrigerated by the chiller heat exchanger 72 is supplied into the chiller showcase 13 , whereby the temperature in the chiller showcase 13 is kept at about 5° C., for example.
  • the refrigerant flowing from the freezer side branch liquid pipe 21 b into the freezer circuit 80 passes through the refrigerant heat exchanger 81 and the drain pan heater 82 . Then, when the refrigerant passes through the freezer expansion valve 83 , the refrigerant has its pressure reduced and then is introduced into the freezer heat exchanger 84 . In the freezer heat exchanger 84 , the refrigerant absorbs heat from the air in the freezer showcase 14 , thereby being evaporated. At this time, in the freezer heat exchanger 84 , the evaporation temperature of the refrigerant is set at about ⁇ 30° C., for example. In the freezer showcase 14 , the air in the freezer showcase 14 refrigerated by the freezer heat exchanger 84 is supplied into the freezer showcase 14 , whereby the temperature in the freezer showcase 14 is kept at about ⁇ 20° C., for example.
  • the refrigerant evaporated in the freezer heat exchanger 84 passes through the suction pipe 88 and is sucked into the booster compressor 85 .
  • the refrigerant compressed by the booster compressor 85 passes through the discharge pipe 98 and the freezer side branch gas pipe 22 b and flows into the first gas side connection piping 22 .
  • the refrigerant sent from the chiller circuit 70 and the refrigerant sent from the freezer circuit 80 merge with each other. These refrigerants pass through the first gas side connection piping 22 and the first low-pressure suction pipe 42 and flow into the first suction pipe 41 a and the second suction pipe 41 b and then are sucked by the DC inverter compressor 31 a and the first non-inverter compressor 31 b .
  • the DC inverter compressor 31 a and the first non-inverter compressor 31 b compress the sucked refrigerants and discharge the refrigerants to the first discharge pipe 48 a and the second discharge pipe 48 b.
  • the refrigerant flowing into the second liquid side connection piping 23 is supplied to the air-conditioning circuit 60 .
  • the refrigerant flowing into the air-conditioning circuit 60 has its pressure reduced when the refrigerant passes through the air-conditioning expansion valve 61 .
  • the refrigerant is introduced into the air-conditioning heat exchanger 62 .
  • the refrigerant absorbs heat from the indoor air, thereby being evaporated.
  • the indoor air cooled by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant evaporated in the air-conditioning heat exchanger 62 passes through the second gas side connection piping 24 and flows into the outdoor circuit 30 and passes through the second gas pipe 51 , the first four-way switching valve 35 , and the second four-way switching valve 36 in sequence and then passes through the second low-pressure gas pipe 44 and the third suction pipe 41 c and then is sucked by the second non-inverter compressor 31 c .
  • the second non-inverter compressor 31 c compresses the sucked refrigerant and discharges the refrigerant to the third discharge pipe 48 c.
  • the defrosting operation shown in FIG. 3 in which the chiller heat exchanger 72 and the freezer heat exchanger 84 are defrosted at the same time and the defrosting operation shown in FIG. 4 in which the chiller heat exchanger 72 is defrosted while the freezer heat exchanger 84 performs a freezing operation can be performed.
  • a refrigerant flow at the time of the defrosting operation is designated by a reference symbol 25 .
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed and the chiller expansion valve 71 and the freezer expansion valve 83 are fully opened, whereas the air-conditioning expansion valve 61 has its degree of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valve SV 2 of the low stage side hot gas passage 89 are opened. In this state, the first non-inverter compressor 31 b and the second non-inverter compressor 31 c are operated.
  • the refrigerant discharged from the first non-inverter compressor 31 b and the refrigerant discharged from the second non-inverter compressor 31 c pass through the respective discharge pipes 48 b , 48 c and merge with each other in the high-pressure pipe 45 .
  • the refrigerant after merging passes through the first four-way switching valve 35 and the first gas pipe 50 and is sent to the outdoor heat exchanger 32 .
  • the refrigerant dissipates heat to the outdoor air, thereby being condensed.
  • the refrigerant condensed in the outdoor heat exchanger 32 passes through the receiver 33 and flows through the first liquid side connection piping 21 and then flows into the second liquid side connection pipe 23 .
  • part of the refrigerant discharged from the first non-inverter compressor 31 b and the second non-inverter compressor 31 c flows through the high stage side hot gas passage 46 , the first low-pressure gas pipe 42 , and the first gas side connection piping 22 and then is distributed to the chiller side branch gas pipe 22 a and the freezer side branch gas pipe 22 b.
  • the refrigerant flowing through the chiller side branch gas pipe 22 a flows into the chiller heat exchanger 72 .
  • the refrigerant dissipates heat to the air in the chiller showcase 13 , thereby being condensed.
  • frost adhering to the chiller heat exchanger 72 is melted.
  • the refrigerant condensed in the chiller heat exchanger 72 passes through the chiller expansion valve 71 and flows through the chiller side branch liquid pipe 21 a and then flows into the second liquid side connection piping 23 and there merges with the refrigerant from the outdoor unit 11 .
  • the refrigerant flowing through the freezer side branch gas pipe 22 b passes through the low stage side hot gas passage 89 and flows into the freezer heat exchanger 84 where the refrigerant dissipates heat to the air in the freezer showcase 14 , thereby being condensed. At that time, frost adhering to the freezer heat exchanger 84 is defrosted.
  • the refrigerant condensed in the freezer heat exchanger 84 passes through the freezer expansion valve 83 , the drain pan heater 82 , the refrigerant heat exchanger 81 , and flows through the freezer side branch liquid pipe 21 b and then flows into the second liquid side connection piping 23 and there merges with the refrigerant from the outdoor unit 11 .
  • the refrigerant after merging in the second liquid side connection piping 23 is supplied to the air-conditioning circuit 60 .
  • the refrigerant flowing into the air-conditioning circuit 60 has its pressure reduced when the refrigerant passes through the air-conditioning expansion valve 61 .
  • the refrigerant is introduced into the air-conditioning heat exchanger 62 .
  • the refrigerant absorbs heat from the indoor air, thereby being evaporated.
  • the indoor air cooled by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant evaporated in the air-conditioning heat exchanger 62 passes through the second gas side connection piping 24 and flows into the outdoor circuit 30 and then passes through the second gas pipe 51 , the first four-way switching valve 35 , and the second four-way switching valve 36 in sequence, and then passes through the second low-pressure gas pipe 44 , the second suction pipe 41 b , and the third suction pipe 41 c , and then is sucked by the first non-inverter compressor 31 b and the second non-inverter compressor 31 c .
  • the first non-inverter compressor 31 b and the second non-inverter compressor 31 c compress the sucked refrigerant and discharge the refrigerant into the second discharge pipe 48 b and the third discharge pipe 48 c , respectively.
  • the chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted at the same time by the use of heat absorbed by the indoor heat exchanger 62 and heat produced by compressing the refrigerant by the first and second non-inverter compressors 31 b , 31 c.
  • FIG. 3 shows the operation using two compressors of the first non-inverter compressor 31 b and the second non-inverter compressor 31 c , but only any one of the compressors may be operated.
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed and the chiller expansion valve 71 is fully opened, whereas the freezer expansion valve 83 and the air-conditioning expansion valve 61 have their degrees of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 is opened and the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed. In this state, the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerant discharged from the first non-inverter compressor 31 b and the refrigerant discharged from the second non-inverter compressor 31 c pass through the respective discharge pipes 48 b , 48 c and merge with each other in the high-pressure pipe 45 .
  • the refrigerant after merging passes through the first four-way switching valve 35 and the first gas pipe 50 and is sent to the outdoor heat exchanger 32 .
  • the refrigerant dissipates heat to the outdoor air, thereby being condensed.
  • the refrigerant condensed in the outdoor heat exchanger 32 passes through the receiver 33 and flows through the first liquid side connection piping 21 and then is distributed to the second liquid side connection piping 23 and the freezer side branch liquid pipe 21 b.
  • the refrigerant flowing into the freezer heat circuit 80 from the freezer side branch gas pipe 21 b passes through the refrigerant heat exchanger 81 and the drain pan heater 82 . Then, when the refrigerant passes through the freezer expansion valve 83 , the refrigerant has its pressure reduced and then is introduced into the freezer heat exchanger 84 .
  • the freezer heat exchanger 84 the refrigerant absorbs heat from the air in the freezer showcase 14 and evaporates.
  • the evaporation temperature of the refrigerant is set to about ⁇ 30° C., for example.
  • the freezer showcase 14 the air in the freezer showcase 14 cooled by the freezer heat exchanger 84 is supplied, whereby the temperature in the freezer showcase 14 is kept at about ⁇ 20° C., for example.
  • the refrigerant evaporated by the freezer heat exchanger 84 passes through the suction pipe 88 and then is sucked by the booster compressor 85 .
  • the refrigerant compressed by the booster compressor 85 passes through the discharge pipe 98 and the freezer side branch gas pipe 22 b and then flows into the first gas side connection piping 22 .
  • the electronic expansion valve 87 disposed in the branch pipe 86 has the degree of opening controlled and performs the function of an economizer. For this reason, the discharge pressure of the booster compressor 85 is increased to a level nearly equal to the discharge pressure of the first non-inverter compressor 31 b and the second non-inverter compressor 31 c.
  • part of the refrigerant discharged from the first non-inverter compressor 31 b and the second non-inverter compressor 31 c flows through the high stage side hot gas passage 46 , the first low-pressure gas pipe 42 , and the first gas side connection piping 22 and then merges with the refrigerant from the freezer unit 14 and then flows through the chiller side branch gas pipe 22 a.
  • the refrigerant flowing through the chiller side branch gas pipe 22 a flows into the chiller heat exchanger 72 .
  • the refrigerant dissipates heat to the air in the chiller showcase 13 , thereby being condensed.
  • frost adhering to the chiller heat exchanger 72 is melted.
  • the refrigerant condensed in the chiller heat exchanger 72 passes through the chiller expansion valve 71 and flows through the chiller side branch liquid pipe 21 a . Then, the refrigerant is distributed, together with the refrigerant from the outdoor unit 11 , to the second liquid side connection piping 23 and the freezer side branch liquid pipe 21 b.
  • the refrigerant flowing through the second liquid side connection piping 23 is supplied to the air-conditioning circuit 60 .
  • the refrigerant flowing into the air-conditioning circuit 60 passes through the air-conditioning expansion valve 61 , the refrigerant has its pressure reduced and then is introduced into the air-conditioning heat exchanger 62 .
  • the refrigerant absorbs heat from the indoor air, thereby being evaporated.
  • the indoor air cooled by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant evaporated in the air-conditioning heat exchanger 62 passes through the second gas side, connection piping 24 and flows into the outdoor heat exchanger 30 and then passes through the second gas pipe 51 , the first four-way switching valve 35 , and the second four-way switching valve 36 in sequence and then passes through the second low-pressure gas pipe 44 , the second suction pipe 41 b , and the third suction pipe 41 c and then is sucked by the first non-inverter compressor 31 b and the second non-inverter compressor 31 c .
  • the first non-inverter compressor 31 b and the second non-inverter compressor 31 c compress the sucked refrigerant and discharge the compressed refrigerant into the second discharge pipe 48 b and the third discharge pipe 48 c.
  • the chiller heat exchanger 72 can be defrosted by the use of heat absorbed by the indoor heat exchanger 62 and the freezer heat exchanger 84 and heat produced by compressing the refrigerant by the compressors 31 b , 31 c , and 85 .
  • FIG. 4 shows the operation using two compressors of the first non-inverter compressor 31 b and the second non-inverter compressor 31 c , but only any one of the compressors may be operated.
  • a heating operation is the operation of refrigerating air in the chiller showcase 13 and the freezer showcase 14 and heating the indoor air by the air-conditioning unit 12 to heat the interior of the store.
  • the first four-way switching valve 35 is set to the second state and the second four-way switching valve 36 and the third four-way switching valve 37 are set to the first state, respectively.
  • the air-conditioning expansion valve 61 is fully opened, whereas the outdoor expansion valve 34 , the chiller expansion valve 71 , and the freezer expansion valve have their degrees of opening suitably adjusted, and the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valve SV 2 of the low stage side hot gas passage 89 are closed.
  • the DC inverter compressor 31 a , the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerant discharged from the DC inverter compressor 31 a , the first non-inverter compressor 31 b , and the second non-inverter compressor 31 c passes through the high-pressure gas pipe 45 , the first four-way switching valve 35 , the second gas pipe 51 , and the second gas side connection piping 24 and then is introduced into the air-conditioning heat exchanger 62 of the air-conditioning circuit 60 .
  • the refrigerant dissipates heat to the indoor air, thereby being condensed.
  • the indoor air heated by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant condensed in the air-conditioning heat exchanger 62 flows through the second liquid side connection piping 23 and then is distributed to the chiller side branch liquid pipe 21 a , the freezer side branch liquid pipe 21 b , and the first liquid side connection piping 21 .
  • the refrigerant flowing through the chiller side branch liquid pipe 21 a flows into the chiller showcase 13 and the refrigerant flowing through the freezer side branch liquid pipe 21 b flows into the freezer showcase 14 .
  • the airs in the showcases are cooled as is the case with the cooling operation.
  • the refrigerant evaporated in the chiller heat exchanger 72 and the refrigerant evaporated in the freezer heat exchanger 84 and then compressed by the booster compressor 85 merge with each other in the first gas side connection piping 22 .
  • the refrigerant flowing through the first gas side connection piping 22 is distributed to the first suction pipe 41 a and the second suction pipe 41 b . Then, the distributed refrigerants are sucked and compressed by the first non-inverter compressor 31 b and the second non-inverter compressor 31 c , respectively.
  • the refrigerant flowing through the first liquid side connection piping 21 flows into the receiver 33 from the third liquid pipe 55 and flows through the fourth liquid pipe 56 and has its pressure reduced by the outdoor expansion valve 34 .
  • the refrigerant having the pressure reduced by the outdoor expansion valve 34 is introduced into the outdoor heat exchanger 32 and there absorbs heat from the outdoor air, thereby being evaporated.
  • the refrigerant evaporated by the outdoor heat exchanger 32 passes through the first four-way switching valve 35 and the second four-way switching valve 36 and then passes through the second low-pressure gas pipe 44 and the third suction pipe 41 c and then is sucked and compressed by the second non-inverter compressor 31 c.
  • the refrigerant absorbs heat in the chiller heat exchanger 72 , the freezer heat exchanger 84 , and the outdoor heat exchanger 32 , and dissipates heat in the air-conditioning heat exchanger 62 .
  • the store is heated by the use of heat that the refrigerant absorbs from the air in the chiller showcase 13 and the freezer showcase 14 in the chiller heat exchanger 72 and the freezer heat exchanger 84 and heat that the refrigerant absorbs from the outside air at the outdoor heat exchanger 32 .
  • a defrosting operation shown in FIG. 6 a defrosting operation shown in which the chiller heat exchanger 72 and the freezer heat exchanger 84 are defrosted at the same time and a defrosting operation shown in FIG. 7 in which the chiller heat exchanger 72 is defrosted while the freezer heat exchanger 84 performs a freezing operation can be performed.
  • the defrosting operation shown in FIG. 6 will be described.
  • the first four-way switching valve 35 and the third four-way switching valve 37 are set to the second state and the second four-way switching valve 36 is set to the first state.
  • the air-conditioning expansion valve 61 , the chiller expansion valve 71 , and the freezer expansion valve 83 are fully opened, whereas the outdoor expansion valve 34 has its degree of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valve SV 2 of the low stage side hot gas passage 89 are opened. In this state, the first non-inverter compressor 31 b and the second non-inverter compressor 31 c are operated.
  • the refrigerant discharged from the first non-inverter compressor 31 b and the refrigerant discharged from the second non-inverter compressor 31 c pass through the respective discharge pipes 48 b , 48 c and merge with each other in the high-pressure pipe 45 .
  • the refrigerant after merging passes through the first four-way switching valve 35 , the second gas pipe 51 , and the second gas side connection piping 24 and is introduced into the outdoor heat exchanger 32 of the air-conditioning circuit 60 where the refrigerant dissipates heat to the indoor air, thereby being condensed.
  • the indoor air heated by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant condensed in the air-conditioning heat exchanger 62 flows through the second liquid side connection piping 23 and then flows into the first liquid side connection piping 21 .
  • part of the refrigerant discharged from the first non-inverter compressor 31 b and the second non-inverter compressor 31 c flows through the high stage side hot gas passage 46 , the first low-pressure gas pipe 42 , and the first gas side connection piping 22 and then are distributed to the chiller side branch gas pipe 22 a and the freezer side branch gas pipe 22 b.
  • the refrigerant flowing through the chiller side branch gas pipe 22 a flows into the chiller heat exchanger 72 .
  • chiller heat exchanger 72 the refrigerant dissipates heat to the air in the chiller showcase 13 , thereby being condensed.
  • frost adhering to the chiller heat exchanger 72 is melted.
  • the refrigerant condensed in the chiller heat exchanger 72 passes through the chiller expansion valve 71 and flows through the chiller side branch liquid pipe 21 a and then flows into the first liquid side connection piping 21 and then merges with the refrigerant from the air-conditioning unit 12 .
  • the refrigerant flowing through the freezer side branch gas pipe 22 b passes through the low stage side hot gas passage 89 and flows into the freezer heat exchanger 84 .
  • the freezer heat exchanger 84 the refrigerant dissipates heat to the air in the freezer showcase 14 , thereby being condensed. At that time, frost adhering to the freezer heat exchanger 84 is melted.
  • the refrigerant condensed in the freezer heat exchanger 84 passes through the freezer expansion valve 83 , the drain pan heater 82 , the refrigerant heat exchanger 81 , and flows through the freezer side branch liquid pipe 21 b and then flows into the first liquid side connection piping 21 and then merges with the refrigerant from the air-conditioning unit 12 .
  • the refrigerant flowing through the first liquid side connection piping 21 flows into the receiver 33 from the third liquid pipe 55 and flows through the fourth liquid pipe 56 and has its pressure reduced by the outdoor expansion valve 34 .
  • the refrigerant having the pressure reduced by the outdoor expansion valve 34 is introduced into the outdoor heat exchanger 32 and there absorbs heat from the outdoor air, thereby being evaporated.
  • the refrigerant evaporated in the outdoor heat exchanger 32 passes through the first four-way switching valve 35 , the second four-way switching valve 36 , the second low-pressure gas pipe 44 , the second suction pipe 41 b , and the third suction pipe 41 c , and then is sucked and compressed by the first non-inverter compressor 31 b and the second non-inverter compressor 31 c.
  • the chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted at the same time by the use of heat absorbed by the outdoor heat exchanger 32 and heat produced by compressing the refrigerant by the first and second non-inverter compressors 31 b , 31 c.
  • FIG. 6 shows the operation using two compressors of the first non-inverter compressor 31 b and the second non-inverter compressor 31 c , but only any one of the compressors may be operated.
  • the first four-way switching valve 35 and the third four-way switching valve 37 are set to the second state and the second four-way switching valve 36 is set to the first state.
  • the air-conditioning expansion valve 61 and the chiller expansion valve 71 are fully opened, whereas the freezer expansion valve 83 and the outdoor expansion valve 34 have their degrees of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 is opened and the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed. In this state, the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerant discharged from the first non-inverter compressor 31 b and the refrigerant discharged from the second non-inverter compressor 31 c pass through the respective discharge pipes 48 b , 48 c and merge with each other in the high-pressure pipe 45 .
  • the refrigerant after merging passes through the first four-way switching valve 35 , the second gas pipe 51 , and the second gas side connection piping 24 and is introduced into the outdoor heat exchanger 32 where the refrigerant dissipates heat to the indoor air, thereby being condensed.
  • the indoor air heated by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant condensed in the air-conditioning heat exchanger 62 flows through the second liquid side connection piping 23 and then is distributed to the freezer side branch liquid pipe 21 b and the first liquid side connection piping 21 .
  • the refrigerant flowing into the freezer circuit 80 from the freezer side branch liquid pipe 21 b passes through the refrigerant heat exchanger 81 and the drain pan heater 82 .
  • the refrigerant passes through the freezer expansion valve 83 , the refrigerant has its pressure reduced and then is introduced into the freezer heat exchanger 84 .
  • the freezer heat exchanger 84 the refrigerant absorbs heat from the air in the freezer showcase 14 , thereby being evaporated.
  • the evaporation temperature of the refrigerant is set to about ⁇ 30° C., for example.
  • the freezer showcase 14 the air in the freezer showcase 14 cooled by the freezer heat exchanger 84 is supplied into the freezer showcase 14 , whereby the temperature in the freezer showcase 14 is kept at about ⁇ 20° C., for example.
  • the refrigerant evaporated by the freezer heat exchanger 84 passes through the suction pipe 88 and then is sucked by the booster compressor 85 .
  • the refrigerant compressed by the booster compressor 85 passes through the discharge pipe 98 and the freezer side branch gas pipe 22 b and then flows into the first gas side connection piping 22 .
  • the electronic expansion valve 87 disposed in the branch pipe 86 has the degree of opening controlled and performs the function of an economizer. For this reason, the discharge pressure of the booster compressor 85 is increased to a level nearly equal to the discharge pressure of the first non-inverter compressor 31 b and the second non-inverter compressor 31 c.
  • part of the refrigerant discharged from the first non-inverter compressor 31 b and the second non-inverter compressor 31 c flows through the high stage side hot gas passage 46 , the first low-pressure gas pipe 42 , and the first gas side connection piping 22 and then merges with the refrigerant from the freezer unit 14 and then flows through the chiller side branch gas pipe 22 a.
  • the refrigerant flowing through the chiller side branch gas pipe 22 a flows into the chiller heat exchanger 72 .
  • the refrigerant dissipates heat to the air in the chiller showcase 13 , thereby being condensed.
  • frost adhering to the chiller heat exchanger 72 is melted.
  • the refrigerant condensed in the chiller heat exchanger 72 passes through the chiller expansion valve 71 and flows through the chiller side branch liquid pipe 21 a . Then, the refrigerant and is distributed, together with the refrigerant from the air-conditioning unit 12 , to the freezer side branch liquid pipe 21 b and the first liquid side connection piping 21 .
  • the refrigerant flowing through the first liquid side connection piping 21 flows into the receiver 33 from the third liquid pipe 55 and flows through the fourth liquid pipe 56 and has it pressure reduced by the outdoor expansion valve 34 .
  • the refrigerant having its pressure reduced by the outdoor expansion valve 34 is introduced into the outdoor heat exchanger 32 .
  • the refrigerant absorbs heat from the outdoor air, thereby being evaporated.
  • the refrigerant evaporated in the outdoor heat exchanger 32 passes through the first four-way switching valve 35 , the second four-way switching valve 36 , the second low-pressure gas pipe 44 , the second suction pipe 41 b , and the third suction pipe 41 c , and then is sucked and compressed by the first non-inverter compressor 31 b and the second non-inverter compressor 31 c.
  • the chiller heat exchanger 72 can be defrosted by the use of heat absorbed by the outdoor heat exchanger 32 and the freezer heat exchanger 84 and heat produced by compressing the refrigerant by the compressors 31 b , 31 c.
  • FIG. 7 shows the operation using two compressors of the first non-inverter compressor 31 b and the second non-inverter compressor 31 c , but only any one of the compressors may be operated.
  • both of the chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted, so it is possible to prevent the construction of the refrigeration system from becoming complex. Moreover, it is possible not only to defrost both of the chiller heat exchanger 72 and the freezer heat exchanger 84 at the same time but also to defrost only one of them. In this manner, the refrigeration system 10 of this embodiment can defrost the chiller heat exchanger 72 and the freezer heat exchanger 84 individually and hence can respond to a variety of patterns of the defrosting operations.
  • chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted by the use of the heat absorbed by the air-conditioning heat exchanger 62 , the heat absorbed by the outdoor heat exchanger 32 , and the heat produced by compressing the refrigerant by the compression mechanism 31 , so the defrosting operation can be performed efficiently.
  • the frost adhering to the chiller heat exchanger 72 and the freezer heat exchanger 84 is melted from outside by the use of an electric heater, the temperature in the refrigerator is easily increased.
  • the frost adhering to the chiller heat exchanger 72 and the freezer heat exchanger 84 is melted from inside by the use of heat of the refrigerant, so an increase in the temperature in the refrigerator can be prevented.
  • the respective heat exchangers 72 , 84 can be defrosted individually, so when one of the heat exchangers 72 , 84 is defrosted earlier, by stopping flowing the hot gas through the heat exchanger, an increase in the temperature in the refrigerator can be prevented with reliability.
  • the function of the economizer is performed in the freezer showcase 14 to increase the discharge pressure of the booster compressor 85 .
  • the function of the economizer is not used, a comparatively large pressure difference is developed between the discharge pressure of the compression mechanism 31 of the outdoor unit 11 and the discharge pressure of the booster compressor 85 , which raises a possibility that the booster compressor 85 might be damaged.
  • the use of the function of the economizer can prevent such a problem.
  • the description of the detailed flow of the refrigerant in the refrigerant circuit 20 has been omitted, but it is also possible to perform only the chilling/freezing operation without performing the air-conditioning operation and to perform only the air-conditioning operation without performing the chilling/freezing operation.
  • a refrigeration system 10 of an embodiment 2, as shown in FIG. 8 is an embodiment that is different from the embodiment 1 in the construction of a part of the outdoor unit 11 .
  • the embodiment 2 is different from the embodiment ° in the construction relating to the high stage side hot gas passage 46 .
  • the hot gas introduction passage 46 of the embodiment 2 has its one end connected to the high-pressure gas pipe 45 and has the other end connected to the fourth port P 4 of the third four-way switching valve 37 .
  • the check valve CV 1 disposed in the first connection pipe 43 a in the embodiment 1 is not disposed in the embodiment 2.
  • the cooling operation and the heating operation can be also performed in the same way as in the embodiment 1, and two or one of the chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted at the time of the cooling operation or the heating operation.
  • the first four-way switching valve 35 , the second four-way switching valve 36 , and the third four-way switching valve 37 are set to the first state, respectively.
  • the outdoor expansion valve 34 is totally closed whereas the air-conditioning expansion valve 61 , the chiller expansion valve 71 , and the freezer expansion valve 83 have their degrees of opening suitably adjusted and the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed.
  • the DC inverter compressor 31 a , the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are actuated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 2 .
  • a refrigeration cycle is performed in which the outdoor heat exchanger 32 is used as a condenser and in which the air-conditioning heat exchanger 62 , the chiller heat exchanger 72 , and the freezer heat exchanger 84 are used as evaporators.
  • the defrosting operation shown in FIG. 10 in which the chiller heat exchanger 72 and the freezer heat exchanger 84 are defrosted at the same time and the defrosting operation shown in FIG. 11 in which the chiller heat exchanger 72 is defrosted while the freezer heat exchanger 84 performs the cooling operation can be performed.
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed and the chiller expansion valve 71 and the freezer expansion valve 83 are fully opened, whereas the air-conditioning expansion valve 61 has its degree of opening suitably adjusted.
  • the second solenoid valve SV 2 of the low stage side hot gas passage 89 is opened. In this state, the first non-inverter compressor 31 b and the second non-inverter compressor 31 c are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 3 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 , the third four-way switching valve 37 , and the first low-pressure gas pipe 42 to the chiller showcase 13 and the freezer showcase 14 .
  • a refrigeration cycle is performed in which the outdoor heat exchanger 32 , the chiller heat exchanger 72 , and the freezer heat exchanger 84 are used as condensers and in which the air-conditioning heat exchanger 62 is used as an evaporator.
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed and the chiller expansion valve 71 is fully opened, whereas the freezer expansion valve 83 and the air-conditioning expansion valve 61 have their degrees of opening suitably adjusted.
  • the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed. In this state, the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 4 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 , the third four-way switching valve 37 , and the first low-pressure gas pipe 42 to the chiller showcase 13 .
  • a refrigeration cycle is performed in which the outdoor heat exchanger 32 and the chiller heat exchanger 72 are used as condensers and in which the air-conditioning heat exchanger 62 and the freezer heat exchanger 84 are used as evaporators.
  • the first four-way switching valve 35 is set to the second state and the second four-way switching valve 36 and the third four-way switching valve 37 are set to the first state, respectively.
  • the air-conditioning expansion valve 61 is fully opened whereas the outdoor expansion valve 34 , the chiller expansion valve 71 , and the freezer expansion valve 83 have their degrees of opening suitably adjusted.
  • the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed. In this state, the DC inverter compressor 31 a , the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 5 .
  • a refrigeration cycle is performed in which the air-conditioning heat exchanger 62 is used as a condenser and in which the outdoor heat exchanger 32 , the chiller heat exchanger 72 , and the freezer heat exchanger 84 are used as evaporators.
  • the defrosting operation shown in FIG. 13 in which the chiller heat exchanger 72 and the freezer heat exchanger 84 are defrosted at the same time and the defrosting operation shown in FIG. 14 in which the chiller heat exchanger 72 is defrosted while the freezer heat exchanger 84 performs the cooling operation can be performed.
  • the first four-way switching valve 35 and the third four-way switching valve 37 are set to the second state and the second four-way switching valve 36 is set to the first state.
  • the air-conditioning expansion valve 61 , the chiller expansion valve 71 , and the freezer expansion valve 83 are fully opened, whereas the outdoor expansion valve 34 has its degree of opening suitably adjusted.
  • the second solenoid valve SV 2 of the low stage side hot gas passage 89 is opened. In this state, the first non-inverter compressor 31 b and the second non-inverter compressor 31 c are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 6 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 , the third four-way switching valve 37 , and the first low-pressure gas pipe 42 to the chiller showcase 13 and the freezer showcase 14 .
  • a refrigeration cycle is performed in which the air-conditioning heat exchanger 62 , the chiller heat exchanger 72 , and the freezer heat exchanger 84 are used as condensers and in which the outdoor heat exchanger 32 is used as an evaporator.
  • the first four-way switching valve 35 and the third four-way switching valve 37 are set to the second state and the second four-way switching valve 36 is set to the first state.
  • the air-conditioning expansion valve 61 and the chiller expansion valve 71 are fully opened, whereas the freezer expansion valve 83 and the outdoor expansion valve 34 have their degrees of opening suitably adjusted.
  • the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed. In this state, the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 7 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 , the third four-way switching valve 37 , and the first low-pressure gas pipe 42 to the chiller showcase 13 .
  • a refrigeration cycle is performed in which the air-conditioning heat exchanger 62 and the chiller heat exchanger 72 are used as condensers and in which the freezer heat exchanger 84 and the outdoor heat exchanger 32 are used as evaporators.
  • the refrigeration system 10 of this embodiment 2 can respond to a variety of patterns of the defrosting operations while preventing the construction of the refrigeration system from becoming complex.
  • this embodiment 2 is the same as the embodiment 1 also in that unlike a refrigeration system of the related art in which a freezer heat exchanger is defrosted by using a chiller heat exchanger as a heat source, there is not a restriction in design such that it is necessary to bring the chiller heat exchanger and the freezer heat exchanger into a good balance between heat absorption and heat dissipation at the time of the defrosting operation.
  • this embodiment 2 is the same as the embodiment 1 also: in that the chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted by the use of the heat absorbed by the air-conditioning heat exchanger 62 and the outdoor heat exchanger 32 and the heat produced by compressing the refrigerant by the compression mechanism 31 , so the defrosting operation can be performed efficiently; and in that the frost adhering to the chiller heat exchanger 72 and the freezer heat exchanger 84 can be melted from inside by the heat of the refrigerant without using an electric heater, whereby an increase in the chiller showcase 13 and the freezer showcase 14 can be prevented.
  • a refrigeration system 10 of an embodiment 3 is an embodiment in which one air-conditioning unit 12 and two freezer units 14 are connected to the outdoor unit 11 , as shown in FIG. 15 , in place of connecting one air-conditioning unit 12 , one chiller showcase 13 , and one freezer showcase 14 to the outdoor unit 11 .
  • Two freezer showcases 14 are connected in parallel to the outdoor unit 11 via two freezer side branch liquid pipes 21 b branched from the first liquid side connection piping 21 and via two freezer side branch gas pipes 22 b branched from the first gas side connection piping 22 .
  • two freezer circuits 80 each of which is provided with the freezer heat exchanger 84 and the booster compressor 85 are connected in parallel.
  • This embodiment 3 just as with the embodiments 1 and 2, can also perform the cooling operation and the heating operation and can defrost two or one of the freezer heat exchangers 84 at the time of the cooling operation and the heating operation.
  • the first four-way switching valve 35 , the second four-way switching valve 36 , and the third four-way switching valve 37 are set to the first state, respectively.
  • the outdoor expansion valve 34 is totally closed, whereas the air-conditioning expansion valve 61 , and each freezer expansion valve 83 have their degrees of opening suitably adjusted and the second solenoid valve SV 2 of the low stage side hot gas passage 89 is closed.
  • the DC inverter compressor 31 a , the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 are actuated.
  • the refrigerant circulates through the refrigerant circuit 10 in the nearly same state as shown in FIG. 2 .
  • a refrigeration cycle is performed in which the outdoor heat exchanger 32 is used as a condenser and in which the air-conditioning heat exchanger 62 and the respective freezer heat exchangers 84 are used as evaporators.
  • the defrosting operation shown in FIG. 17 in which two freezer heat exchangers 84 are defrosted at the same time and the defrosting operation shown in FIG. 18 in which one freezer heat exchanger 84 is defrosted while the other freezer heat exchanger 84 performs the refrigerating operation can be performed.
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed and the respective freezer expansion valves 83 are fully opened, whereas the air-conditioning expansion valve 61 has its degree of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valves SV 2 of the respective low stage side hot gas passages 89 are opened. In this state, the first non-inverter compressor 31 b and the second non-inverter compressor 31 c are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 3 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 and the first low-pressure gas pipe 42 and then is branched to two freezer side branch gas pipes 22 b and that the branched refrigerants then flow to the respective freezer showcases 14 .
  • a refrigeration cycle is performed in which the outdoor heat exchanger 32 , the respective freezer heat exchangers 84 are used as condensers and in which the air-conditioning heat exchanger 62 is used as an evaporator.
  • the defrosting operation shown in FIG. 18 is an embodiment in which the freezer showcase 14 shown on the upper side in the drawing performs the defrosting operation.
  • this freezer showcase 14 is referred to as a defrosting side showcase and the freezer showcase 14 shown on the lower side in the drawing is referred to as a refrigerating side showcase.
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed, whereas the freezer expansion valve 83 of the refrigerating side showcase and the air-conditioning expansion valve 61 have their degrees of opening suitably adjusted and the freezer expansion valve 83 of the defrosting side showcase is fully opened.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 is opened and the second solenoid valve SV 2 of the low stage side hot gas passage 89 of the defrosting side showcase is opened and the second solenoid valve SV 2 of the low stage side hot gas passage 89 of the refrigerating side showcase is closed.
  • the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 of the refrigerating side showcase are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 4 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 and the first low-pressure gas pipe 42 to freezer heat exchanger 84 of the defrosting side showcase.
  • a refrigeration cycle is performed in which the outdoor heat exchanger 32 and the freezer heat exchanger 84 of the defrosting side showcase are used as condensers and in which the air-conditioning heat exchanger 62 and the freezer heat exchanger 84 of the refrigerating side showcase are used as evaporators.
  • the first four-way switching valve 35 is set to the second state and the second four-way switching valve 36 and the third four-way switching valve 37 are set to the first state, respectively.
  • the air-conditioning expansion valve 61 is fully opened whereas the outdoor expansion valve 34 and the respective freezer expansion valves 83 have their degrees of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valve SV 2 of the low stage side hot gas passage 89 are closed.
  • the DC inverter compressor 31 a , the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the respective booster compressors 85 are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the nearly same state as shown in FIG. 5 .
  • a refrigeration cycle is performed in which the air-conditioning heat exchanger 62 is used as a condenser and in which the outdoor heat exchanger 32 and the respective freezer heat exchangers 84 are used as evaporators.
  • the defrosting operation shown in FIG. 20 in which two freezer heat exchangers 84 are defrosted at the same time and the defrosting operation shown in FIG. 21 in which one freezer heat exchanger 84 is defrosted while the other freezer heat exchanger 84 performs the refrigerating operation can be performed.
  • the first four-way switching valve 35 and the third four-way switching valve 37 are set to the second state and the second four-way switching valve 36 is set to the first state.
  • the air-conditioning expansion valve 61 and the respective freezer expansion valves 83 are fully opened, whereas the outdoor expansion valve 34 has its degree of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valves SV 2 of the respective low stage side hot gas passages 89 are opened. In this state, the first non-inverter compressor 31 b and the second non-inverter compressor 31 c are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 6 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 and the first low-pressure gas pipe 42 and then is distributed to two freezer side branch gas pipes 22 b and that the distributed refrigerants flow to the respective freezer showcases 14 .
  • a refrigeration cycle is performed in which the air-conditioning heat exchanger 62 and the respective freezer heat exchangers 84 are used as condensers and in which the outdoor heat exchanger 32 is used as an evaporator.
  • the defrosting operation shown in FIG. 21 is an embodiment in which the freezer showcase 14 shown on the upper side in the drawing performs the defrosting operation.
  • the first four-way switching valve 35 and the third four-way switching valve 37 are set to the second state and the second four-way switching valve 36 is set to the first state.
  • the freezer expansion valve 83 of the refrigerating side showcase and the outdoor expansion valve 34 have their degrees of opening suitably adjusted, whereas the air-conditioning expansion valve 61 and the freezer expansion valve 83 of the defrosting side showcase are fully opened.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 is opened and the second solenoid valve SV 2 of the low stage side hot gas passage 89 of the defrosting side showcase is opened, whereas the second solenoid valve SV 2 of the low stage side hot gas passage 89 of the refrigerating side showcase is closed.
  • the first non-inverter compressor 31 b , the second non-inverter compressor 31 c , and the booster compressor 85 of the cooling side showcase are operated.
  • the refrigerant circulates through the refrigerant circuit 10 in the same state as shown in FIG. 7 except that part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 10 flows through the high stage side hot gas passage 46 and the first low-pressure gas pipe 42 to the freezer heat exchanger 84 of the defrosting side showcase.
  • a refrigeration cycle is performed in which the air-conditioning heat exchanger 62 and the freezer heat exchanger 84 of the defrosting side showcase are used as condensers and in which the freezer heat exchanger 84 of the refrigerating side showcase and the outdoor heat exchanger 32 are used as evaporators.
  • the refrigeration system 10 of this embodiment 3 can respond to a variety of patterns of the defrosting operations while preventing the construction of the refrigeration system from becoming complex.
  • the other freezer heat exchangers 84 can perform the refrigerating operation.
  • this embodiment 3 is the same as the embodiments 1 and 2 also in that there is not a restriction in design such that it is necessary to bring heat absorption and heat dissipation in the chiller heat exchanger and the freezer heat exchanger into a good balance at the time of the defrosting operation.
  • this embodiment 3 is the same as the embodiments 1 and 2 also: in that the freezer heat exchangers 84 can be defrosted by the use of the heat absorbed by the air-conditioning heat exchanger 62 and the outdoor heat exchanger 32 and the heat produced by compressing the refrigerant by the compression mechanism 31 , so the defrosting operation can be performed efficiently; and in that the frosts adhering to the freezer heat exchangers 84 can be melted from inside by the heat of the refrigerant without using an electric heater, which can prevent an increase of the temperature in the chiller showcase 13 and the freezer showcase 14 .
  • a refrigeration system 10 of an embodiment 4 is basically equivalent to that of the embodiment 1 in the construction of the refrigerant circuit 20 , but is different from that of the embodiment 1 in the defrosting operation.
  • the refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 is further compressed by the booster compressor 85 and then the discharged refrigerant is supplied to the freezer heat exchanger 84 .
  • part of the refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 passes through the low stage side hot gas passage 89 and is supplied to the freezer heat exchanger 84 and the other part of the refrigerant is compressed by the booster compressor 85 and then is merged with the refrigerant flowing through the low stage side hot gas passage 89 from the compression mechanism 31 and the refrigerant after merging is supplied to the freezer heat exchanger 84 .
  • part of the refrigerant condensed by the freezer heat exchanger 84 is supplied for the liquid injection into the booster compressor 85 .
  • the hot gas introduction passage 46 , 89 is divided into a first introduction passage 96 for introducing the refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into the booster compressor 85 and a second introduction passage 97 for introducing the refrigerant discharged from the booster compressor 85 into the freezer heat exchanger 84 .
  • the second introduction passage 97 is connected to the compression mechanism 31 of the outdoor circuit 30 and the freezer heat exchanger 84 (the second introduction passage 97 is a passage including the low stage side hot gas passage 89 ).
  • the first introduction passage 96 is branched from second introduction passage 97 and is connected to the booster compressor 85 so as to introduce part of the refrigerant discharged from the compression mechanism 31 of the outdoor circuit 30 into the booster compressor 85 .
  • the discharge pipe 98 of the booster compressor 85 is connected to the compression mechanism 31 side of the outdoor circuit 30 in the second introduction passage 97 .
  • the branch pipe 86 connected to the low-pressure side passage 81 b of the refrigerant heat exchanger 81 constructs a liquid injection passage 99 for introducing part of the liquid refrigerant flowing out of the freezer heat exchanger 84 to the booster compressor 85 in the period during which the freezer heat exchanger 84 is defrosted.
  • the refrigeration system 10 of the embodiment 4 switches between a defrosting operation (first defrosting operation) shown in FIG. 3 of the embodiment 1 and a defrosting operation (second defrosting operation) shown in FIG. 22 , which will be described later. These two defrosting operations are switched according to the detection temperature of the heat exchanger temperature sensor 90 disposed in the freezer heat exchanger 84 .
  • the first defrosting operation shown in FIG. 3 is performed.
  • the first non-inverter compressor 31 b and the second non-inverter compressor 31 c of the outdoor circuit 30 are operated, whereas the DC inverter compressor 31 a and the booster compressor 85 are bought into a stop state and both of the chiller heat exchanger 72 and the freezer heat exchanger 84 are defrosted.
  • the first defrosting operation is shifted to the second defrosting operation.
  • the first four-way switching valve 35 and the second four-way switching valve 36 are set to the first state and the third four-way switching valve 37 is set to the second state.
  • the outdoor expansion valve 34 is totally closed and the chiller expansion valve 71 and the freezer expansion valve 83 are fully opened, whereas the air-conditioning expansion valve 61 has its degree of opening suitably adjusted.
  • the first solenoid valve SV 1 of the high stage side hot gas passage 46 and the second solenoid valve SV 2 of the low stage side hot gas passage 89 are opened.
  • the electronic expansion valve 87 of the branch pipe 86 as the liquid injection passage 99 has the degree of opening suitably adjusted and the booster compressor 85 is actuated.
  • the refrigerant discharged in this state from the first non-inverter compressor 31 b and the refrigerant discharged from the second non-inverter compressor 31 c pass through the respective discharge pipes 48 b , 48 c and merge with each other in the high-pressure pipe 45 .
  • the refrigerant after merging passes through the first four-way switching valve 35 and the first gas pipe 50 and is sent to the outdoor heat exchanger 32 .
  • the refrigerant dissipates heat to the outdoor air, thereby being condensed.
  • the refrigerant condensed in the outdoor heat exchanger 32 passes through the receiver 33 and flows through the first liquid side connection piping 21 and then flows into the second liquid side connection piping 23 .
  • part of the refrigerant discharged from the first non-inverter compressor 31 b and the second non-inverter compressor 31 c flows through the high stage side hot gas passage 46 , the first low-pressure gas pipe 42 , and the first gas side connection piping 22 and then is distributed to the chiller side branch gas pipe 22 a and the freezer side branch gas pipe 22 b.
  • the refrigerant flowing through the chiller side branch gas pipe 22 a flows into the chiller heat exchanger 72 and there dissipates heat to the air in the chiller showcase 13 , thereby being condensed. At that time, frost adhering to the chiller heat exchanger 72 is melted.
  • the refrigerant condensed in the chiller heat exchanger 72 passes through the chiller expansion valve 71 and flows through the chiller side branch liquid pipe 21 a and then flows into the second liquid side connection piping 23 and then merges with the refrigerant from the outdoor unit 11 .
  • the refrigerant flowing through the freezer side branch gas pipe 22 b passes through the second introduction passage 97 including the low stage side hot gas passage 89 and part of the refrigerant flows into the freezer heat exchanger 84 and the other part of the refrigerant passes through the first introduction passage 96 and is sucked by the booster compressor 85 .
  • the refrigerant compressed by the booster compressor 85 flows through the discharge pipe 98 and is sent to the low stage side hot gas passage 89 and then is merged with the refrigerant discharged from the compressor 31 of the outdoor circuit 30 . Then, the refrigerant merged in the low stage side hot gas passage 89 flows into the freezer heat exchanger 84 . In other words, in the freezer circuit 80 , part of the refrigerant is compressed and circulated by the booster compressor 85 and the input heat of the booster compressor 85 is given to the refrigerant.
  • the refrigerant dissipates heat to the air in the freezer showcase 14 , thereby being condensed. At that time, frost adhering to the freezer heat exchanger 84 is melted.
  • the refrigerant condensed in the freezer heat exchanger 84 passes through the freezer expansion valve 83 , the drain pan heater 82 , and the refrigerant heat exchanger 81 and then flows through the freezer side branch liquid pipe 21 b and then flows into the second liquid side connection piping 23 and then merges with the refrigerant from the outdoor unit 11 .
  • the degree of opening of the electronic expansion valve 87 is adjusted according to the temperature of the refrigerant discharged from the booster compressor 85 .
  • the degree of opening of the electronic expansion valve 87 is made larger.
  • part of the refrigerant condensed by the freezer heat exchanger 84 is passed through the branch pipe 86 of the liquid injection passage 99 and is sent to the booster compressor 85 .
  • the refrigerant sucked into the booster compressor 85 is refrigerated.
  • this can prevent the temperature of the refrigerant discharged from the booster compressor 85 from being abnormally increased.
  • the refrigerants merged with each other in the second liquid side connection piping 23 are supplied to the air-conditioning circuit 60 . Subsequent operations are the same as in the embodiment shown in FIG. 3 .
  • the refrigerant flowing into the air-conditioning circuit 60 passes through the air-conditioning expansion valve 61 , the refrigerant has its pressure reduced and then is introduced into the air-conditioning heat exchanger 62 .
  • the refrigerant absorbs heat from the indoor air, thereby being evaporated.
  • the indoor air refrigerated by the air-conditioning heat exchanger 62 is supplied into the store.
  • the refrigerant evaporated in the air-conditioning heat exchanger 62 passes through the second gas side connection piping 24 and flows into the outdoor circuit 30 and then passes through the second gas pipe 51 , the first four-way switching valve 35 , and the second four-way switching valve 36 in sequence, and then passes through the second low-pressure gas pipe 44 , the second suction pipe 41 b , and the third suction pipe 41 c , and then is sucked by the first non-inverter compressor 31 b and the second non-inverter compressor 31 c .
  • the first non-inverter compressor 31 b and the second non-inverter compressor 31 c compress the sucked refrigerant and discharge the compressed refrigerant into the second discharge pipe 48 b and the third discharge pipe 48 c.
  • the chiller heat exchanger 72 and the freezer heat exchanger 84 can be defrosted at the same time by the use of heat absorbed by the indoor heat exchanger 62 and heat produced by compressing the refrigerant by the first and second non-inverter compressors 31 b , 31 c of the outdoor circuit 30 and the booster compressor 85 of the freezer circuit 80 .
  • the same operation as shown in FIG. 4 can be also performed and the operation can be also performed in which only the freezer heat exchanger 84 is defrosted by closing the chiller expansion valve 71 .
  • this embodiment 4 can switch the first defrosting operation and the second defrosting operation and when the defrosting capacity of the freezer heat exchanger 84 is not sufficient in the first defrosting operation, the second defrosting operation of operating also the booster compressor 85 is operated. For this reason, according to the embodiment 4, heat to be given to the refrigerant by the second defrosting operation can be increased and hence the defrosting capacity of the freezer heat exchanger 84 can be increased. Thus, the freezer heat exchanger 84 can be effectively defrosted by the second defrosting operation.
  • an abnormal increase in the temperature of the refrigerant discharged from the booster compressor 85 can be prevented by injecting liquid into the booster compressor 85 during the second defrosting operation, so the booster compressor 85 can be protected with reliability.
  • the branch pipe 86 of the liquid injection passage 99 is connected to the intermediate-pressure position of the booster compressor 85 , but this branch pipe 86 may be connected to the first introduction passage 96 of the suction pipe of the booster compressor 85 .
  • an abnormal increase in the temperature of the refrigerant discharged from the booster compressor 85 can be prevented by injecting the liquid into the booster compressor 85 , but the operating capacity of the booster compressor 85 may be controlled in place of injecting the liquid. This can also prevent an abnormal increase in the temperature of the refrigerant discharged from the booster compressor 85 .
  • a refrigeration system 10 of an embodiment 5 is an embodiment that is different from the refrigeration system 10 of the embodiment 1 in a part of the construction of the refrigerant circuit 20 and also in the construction of the hot gas introduction passages 100 , 102 .
  • the points in which this embodiment 5 is different from the embodiment 1 will be mainly described below.
  • the sensors are omitted in the drawing.
  • the high-pressure introduction pipe 47 shown in FIG. 1 is not shown in the outdoor unit 11 , but the high-pressure introduction pipe 47 is provided, just as with the embodiment 1, to introduce the high pressure of the refrigerant circuit 20 into the fourth port P 4 of the third four-way switching valve 37 .
  • the refrigerant heat exchanger 81 is not provided but the gas side piping 110 ( 88 ) of the freezer heat exchanger 84 is connected to the suction side of the booster compressor 85 .
  • An oil separator 120 is disposed in the discharge pipe 98 of the booster compressor 85 and an oil return pipe 122 having a capillary tube 121 is connected between the oil separator 120 and the suction pipe 111 of the booster compressor 85 .
  • a bypass piping 125 bypassing the booster compressor 85 when the booster compressor 85 fails is connected to the suction pipe 111 and the discharge pipe 98 of the booster compressor 85 .
  • This bypass piping 125 has a check valve CV 10 disposed therein.
  • the hot gas introduction passage 100 is not disposed individually on the higher stage side and the lower stage side but is constructed of one piping connected to the discharge line (high-pressure gas pipe) 45 of the compression mechanism 31 of the outdoor unit 11 and to the gas side piping 110 of the freezer heat exchanger 84 .
  • This hot gas introduction passage 100 has an electronic expansion valve 101 disposed therein as a flow control mechanism.
  • the hot gas introduction passage 100 not only to the freezer heat exchanger 84 but also, as shown by a broken line in FIG. 23 , to the gas side piping 112 of the chiller heat exchanger 72 by a branch pipe (hot gas introduction passage) 102 disposed in the hot gas introduction passage 100 and to provide a switching mechanism 103 such as a three-way valve capable of switching or selecting a hot gas flow to the freezer heat exchanger 84 and a hot gas flow to the chiller heat exchanger 72 .
  • a switching mechanism 103 such as a three-way valve capable of switching or selecting a hot gas flow to the freezer heat exchanger 84 and a hot gas flow to the chiller heat exchanger 72 .
  • the freezer heat exchanger 84 when the freezer heat exchanger 84 is defrosted, part of the refrigerant discharged from the compression mechanism 31 of the outdoor unit 11 flows through the hot gas introduction passage 100 and is introduced into the freezer heat exchanger 84 .
  • the frost adhering to the freezer heat exchanger 84 is melted by the heat of the high-pressure refrigerant.
  • the refrigerant is evaporated in the chiller heat exchanger 72 , the air-conditioning heat exchanger 62 , or the outdoor heat exchanger 32 and then is sucked by the compressor mechanism 31 .
  • the above-mentioned embodiments may be constructed in the following manner.
  • an example has been described in which one air-conditioning unit 12 , one chiller showcase 13 , and one freezer showcase 14 are connected, but the numbers of the air-conditioning unit 12 , the chiller showcase 13 , and the freezer showcase 14 may be changed as appropriate.
  • the refrigeration system 10 of each embodiment does not need to be provided with the air-conditioning unit 12 .
  • the compression mechanism 31 of the outdoor unit 11 is constructed of three compressors 31 a , 31 b , and 31 c in the respective embodiments, the number of compressors may be changed and when the air-conditioning unit 12 is not provided, the number of compressor may be one.
  • the embodiment 4 is an embodiment in which the effect of the defrosting operation is enhanced by utilizing the booster compressor 85 at the time of defrosting the freezer heat exchanger 84 in the embodiment 1.
  • the same idea can be applied also to the embodiment 2 and the embodiment 3.
  • the refrigerant discharged from the compressor mechanism 31 of the outdoor unit 11 is circulated while part of the refrigerant is supplied to the freezer heat exchanger 84 and while the other part of the refrigerant is supplied to the booster compressor 85 .
  • the entire refrigerant discharged from the compressor mechanism 31 may be supplied to and compressed by the booster compressor 85 and then be supplied to the freezer heat exchanger 84 .
  • the present invention is useful for a refrigeration system having a refrigerant circuit of a vapor compression type refrigeration cycle of the construction in which plural lines of refrigeration circuits each having a refrigeration heat exchanger are connected to an outdoor circuit provided with an outdoor heat exchanger and a compression mechanism and in which an auxiliary compressor is connected in series to the refrigeration heat exchanger in at least one line of refrigeration circuit.

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  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
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  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
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TWI316596B (ja) 2009-11-01
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TW200643351A (en) 2006-12-16
EP1892486A1 (en) 2008-02-27
AU2006258762A1 (en) 2006-12-21

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