US20240310092A1 - Refrigeration cycle apparatus - Google Patents

Refrigeration cycle apparatus Download PDF

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Publication number
US20240310092A1
US20240310092A1 US18/263,405 US202118263405A US2024310092A1 US 20240310092 A1 US20240310092 A1 US 20240310092A1 US 202118263405 A US202118263405 A US 202118263405A US 2024310092 A1 US2024310092 A1 US 2024310092A1
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Prior art keywords
heat exchanger
refrigerant
temperature sensor
flow rate
degree
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US18/263,405
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English (en)
Inventor
Soichiro KOSHI
Takuya Matsuda
Hiroki Ishiyama
Yusuke Tashiro
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Assigned to MITSUBISHI ELECTRIC CORPORATION reassignment MITSUBISHI ELECTRIC CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MATSUDA, TAKUYA, ISHIYAMA, HIROKI, KOSHI, Soichiro, TASHIRO, YUSUKE
Publication of US20240310092A1 publication Critical patent/US20240310092A1/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
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F25B41/22—Disposition of valves, e.g. of on-off valves or flow control valves between evaporator and compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • 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
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/39—Dispositions with two or more expansion means arranged in series, i.e. multi-stage expansion, on a refrigerant line leading to the same evaporator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
    • F25B2313/0234—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in series arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
    • F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—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
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/23—Separators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/19—Calculation of parameters
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2501—Bypass valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2509—Economiser valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2513—Expansion valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2515—Flow valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a condenser
    • F25B2700/21162—Temperatures of a condenser of the refrigerant at the inlet of the condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a condenser
    • F25B2700/21163—Temperatures of a condenser of the refrigerant at the outlet of the condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2117—Temperatures of an evaporator
    • F25B2700/21174—Temperatures of an evaporator of the refrigerant at the inlet of the evaporator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2117—Temperatures of an evaporator
    • F25B2700/21175—Temperatures of an evaporator of the refrigerant at the outlet of the evaporator

Definitions

  • the present disclosure relates to a refrigeration cycle apparatus.
  • Such a refrigeration cycle apparatus includes a compressor, a condenser, a decompressor, a first evaporator, a second evaporator, and a gas-liquid separator, which are connected, and is configured to guide refrigerant in gaseous state separated in the gas-liquid separator to an inlet side of the compressor and guide refrigerant in liquid state separated in the gas-liquid separator to the second evaporator.
  • PTL 1 can improve the efficiency of operating a refrigeration cycle by separating the refrigerant into refrigerant in gaseous state and refrigerant in liquid state by the gas-liquid separator before guiding the refrigerant in liquid state to the second evaporator.
  • PTL 1 discloses a technique of exclusively applying the gas-liquid separator to the evaporator. As a result, a system in which a heat exchanger is caused to function not only as an evaporator but also as a condenser fails to efficiently utilize such a technique.
  • An object of the present disclosure is to provide a refrigeration cycle apparatus that can have operating efficiency improved with the use of a gas-liquid separator when a heat exchanger is caused to function as either an evaporator or a condenser.
  • the present disclosure relates to a refrigeration cycle apparatus.
  • the refrigeration cycle apparatus includes a compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, an expansion device, a gas-liquid separator, a first flow rate control device, and a switch device.
  • the switch device is configured to switch a refrigerant circulation path between a first route corresponding to a first operation mode and a second route corresponding to a second operation mode.
  • refrigerant flows in order of the compressor, the first heat exchanger, the expansion device, the second heat exchanger, and the gas-liquid separator, the refrigerant in liquid state discharged from the gas-liquid separator flows into the third heat exchanger, the refrigerant in gaseous state discharged from the gas-liquid separator joins, through the first flow rate control device, the refrigerant discharged from the third heat exchanger at a first junction point, and the refrigerant after joining at the first junction point flows to the compressor.
  • the refrigerant flows in order of the compressor, the second heat exchanger, and the gas-liquid separator
  • the refrigerant in gaseous state discharged from the gas-liquid separator flows through the first flow rate control device into the third heat exchanger
  • the refrigerant in liquid state discharged from the gas-liquid separator joins the refrigerant discharged from the third heat exchanger at a second junction point
  • the refrigerant after joining at the second junction point flows in order of the expansion device, the first heat exchanger, and the compressor.
  • the refrigeration cycle apparatus can have operating efficiency improved with the use of the gas-liquid separator when the heat exchanger is caused to function as either an evaporator or a condenser.
  • FIG. 1 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus (Embodiment 1).
  • FIG. 2 shows a refrigerant flow in a first operation mode of the refrigeration cycle apparatus (Embodiment 1).
  • FIG. 3 shows a refrigerant flow in a second operation mode of the refrigeration cycle apparatus (Embodiment 1).
  • FIG. 4 is a p-h diagram showing changes in the state of refrigerant in the first operation mode (Embodiment 1).
  • FIG. 5 is a p-h diagram showing changes in the state of refrigerant in the second operation mode (Embodiment 1).
  • FIG. 6 is a flowchart for describing control of a controller in the first operation mode (Embodiment 1).
  • FIG. 7 is a flowchart for describing control of the controller in the second operation mode (Embodiment 1).
  • FIG. 8 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus (Embodiment 2).
  • FIG. 9 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus (Embodiment 3).
  • FIG. 10 is a flowchart for describing control of a controller in the second operation mode (Embodiment 3).
  • FIG. 1 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus 100 according to Embodiment 1.
  • Refrigeration cycle apparatus 100 includes a refrigerant circuit composed of at least a compressor 1 , an expansion device 3 , a four-way valve 4 , a gas-liquid separator 6 , a first heat exchanger 10 , a second heat exchanger 20 , a third heat exchanger 30 , a first flow rate control device 51 , and a controller 90 .
  • First heat exchanger 10 is mounted in an indoor unit.
  • Second heat exchanger 20 and third heat exchanger 30 are mounted in an outdoor unit.
  • a gas-liquid separator 6 is disposed between second heat exchanger 20 and third heat exchanger 30 .
  • This configuration is equivalent to a configuration in which a heat exchanger on the outdoor unit side is divided into two heat exchangers, and gas-liquid separator 6 is disposed between one of the heat exchangers and the other heat exchanger.
  • Second heat exchanger 20 has a first port P 1 and a second port P 2 .
  • Third heat exchanger 30 has a third port P 3 and a fourth port P 4 .
  • Gas-liquid separator 6 includes an inflow port P 61 , a gas discharge port P 62 , and a liquid discharge port P 63 .
  • a first flow rate control device 51 which adjusts a flow rate of the refrigerant, is provided between gas discharge port P 62 and third heat exchanger 30 .
  • First flow rate control device 51 includes a valve for adjusting a flow rate of the refrigerant.
  • First flow rate control device 51 adjusts a degree of opening of the valve to change a flow rate of the refrigerant.
  • Gas discharge port P 62 is connected via first flow rate control device 51 to third port P 3 of third heat exchanger 30 .
  • Gas discharge port P 62 discharges the refrigerant in gaseous state from gas-liquid separator 6 .
  • Liquid discharge port P 63 is connected to fourth port P 4 of third heat exchanger 30 . Liquid discharge port P 63 discharges the refrigerant in liquid state from gas-liquid separator 6 .
  • the refrigerant in gaseous state is referred to as gaseous refrigerant
  • the refrigerant in liquid state is referred to as liquid refrigerant.
  • the term “refrigerant” is merely used.
  • Four-way valve 4 has a first switch port P 41 , a second switch port P 42 , a third switch port P 43 , and a fourth switch port P 44 .
  • An outlet port of compressor 1 is connected to first switch port P 41
  • an inlet port of compressor 1 is connected to second switch port P 42 .
  • the refrigerant circuit of refrigeration cycle apparatus 100 is provided with a first check valve 41 , a second check valve 42 , a third check valve 43 , and a fourth check valve 44 .
  • First check valve 41 is provided between fourth switch port P 44 of four-way valve 4 and a point a, shown in FIG. 1 , on the refrigerant circuit.
  • Point a corresponds to a first junction point at which the refrigerant discharged from third port P 3 of third heat exchanger 30 joins the refrigerant discharged from first flow rate control device 51 .
  • First check valve 41 interrupts a flow of the refrigerant from fourth switch port P 44 toward first junction point a.
  • Second check valve 42 is provided between fourth switch port P 44 of four-way valve 4 and first port P 1 of second heat exchanger 20 . Second check valve 42 interrupts a flow of the refrigerant from expansion device 3 toward fourth switch port P 44 of four-way valve 4 .
  • Third check valve 43 is provided among fourth switch port P 44 , expansion device 3 , and first port P 1 of second heat exchanger 20 . Third check valve 43 interrupts a flow of the refrigerant from the fourth switch port toward expansion device 3 .
  • Fourth check valve 44 is provided between expansion device 3 and a point b, shown in FIG. 1 , on the refrigerant circuit.
  • Point b corresponds to a second junction point at which the refrigerant discharged from fourth port P 4 of third heat exchanger 30 joins the refrigerant discharged from liquid discharge port P 63 of gas-liquid separator 6 .
  • Fourth check valve 44 interrupts a flow of the refrigerant from expansion device 3 to second junction point b.
  • Four-way valve 4 changes between a first state and a second state.
  • first switch port P 41 communicates with third switch port P 43
  • second switch port P 42 communicates with fourth switch port P 44
  • first switch port P 41 communicates with fourth switch port P 44
  • second switch port P 42 communicates with third switch port P 43 .
  • Four-way valve 4 changes between the first state and the second state, thus switching the direction in which the refrigerant discharged from compressor 1 flows through a flow path.
  • first check valve 41 , second check valve 42 , third check valve 43 , and fourth check valve 44 function, the order in which the refrigerant circulates is switched between a first order and a second order.
  • the operation mode of refrigeration cycle apparatus 100 is switched between the first operation mode and the second operation mode.
  • first operation mode high-pressure refrigerant flows into first heat exchanger 10 .
  • second operation mode low-pressure refrigerant flows into first heat exchanger 10 .
  • first heat exchanger 10 is mounted in the indoor unit
  • the first operation mode corresponds to a heating operation
  • the second operation mode corresponds to a cooling operation.
  • Controller 90 sets four-way valve 4 to the first state in the first operation mode and sets four-way valve 4 to the second state in the second operation mode.
  • Switch device 40 switches the route in which the refrigerant discharged from compressor 1 circulates between a first route corresponding to the first operation mode and a second route corresponding to the second operation mode.
  • the refrigerant circuit of refrigeration cycle apparatus 100 is provided with a plurality of temperature sensors including a first temperature sensor 71 , a second temperature sensor 72 , and a third temperature sensor 73 .
  • First temperature sensor 71 is provided on the side of gas-liquid separator 6 on which the refrigerant in gaseous state is discharged. More specifically, first temperature sensor 71 is provided between first flow rate control device 51 and the side of gas-liquid separator 6 on which the refrigerant in gaseous state is discharged.
  • Second temperature sensor 72 is provided on the third port P 3 side of third heat exchanger 30 . More specifically, second temperature sensor 72 is provided between first junction point a and the third port P 3 side of third heat exchanger 30 .
  • Third temperature sensor 73 is provided on the fourth port P 4 side of third heat exchanger 30 . More specifically, third temperature sensor 73 is provided between second junction point b and the fourth port P 4 side of third heat exchanger 30 .
  • Controller 90 includes a processor 91 and a memory 92 .
  • Memory 92 includes a Read Only Memory (ROM) and a Random Access Memory (RAM).
  • Processor 91 deploys a program stored in the ROM to the RAM or the like and executes the program.
  • the program stored in the ROM is a program in which a procedure of controller 90 is described.
  • Controller 90 controls each device in refrigeration cycle apparatus 100 according to the program stored in memory 92 .
  • controller 90 controls compressor 1 , expansion device 3 , four-way valve 4 , and first flow rate control device 51 .
  • second heat exchanger 20 is located upstream of the refrigerant and third heat exchanger 30 is located downstream of the refrigerant, where compressor 1 is a starting point, in either the first route or the second route, as apparent from the description below.
  • the present disclosure will be described by taking a zeotropic refrigerant mixture, such as R466A, as an example of the refrigerant.
  • the zeotropic refrigerant mixture is obtained by mixing two or more types of refrigerant having different boiling points.
  • the zeotropic refrigerant mixture is characterized by divergence that occurs between saturated gas temperature and saturated liquid temperature under constant pressure.
  • the saturated gas temperature is usually higher than the saturated liquid temperature.
  • Such a temperature difference is referred to as a temperature gradient.
  • the presence of temperature gradient may cause an imbalance in the temperature in the heat exchanger, leading to reduced operating efficiency.
  • the present disclosure proposes a configuration that can improve operating performance while reducing a pressure loss when the zeotropic refrigerant mixture is used.
  • the present disclosure proposes a configuration applicable to either the first operation mode or the second operation mode.
  • the heat exchanger in the outdoor unit is divided into second heat exchanger 20 on the upstream side and third heat exchanger 30 on the downstream side, and gas-liquid separator 6 is disposed in the flow path at some midpoint between second heat exchanger 20 and third heat exchanger 30 .
  • liquid refrigerant or gaseous refrigerant is flowed to third heat exchanger 30 on the downstream side according to the operation mode, to thereby improve operating capability.
  • the refrigerant applicable to refrigeration cycle apparatus 100 is not limited to the zeotropic refrigerant mixture.
  • FIG. 2 shows a refrigerant flow in the first operation mode of refrigeration cycle apparatus 100 .
  • the refrigerant flow in the first operation mode will be described with reference to FIG. 2 .
  • controller 90 controls four-way valve 4 such that the flow path indicated by the solid line in FIG. 2 is formed in four-way valve 4 .
  • the refrigerant flows through the refrigerant circuit of refrigeration cycle apparatus 100 , as indicated by the arrows, by the action of switch device 40 including four-way valve 4 .
  • the refrigerant discharged from compressor 1 flows through first switch port P 41 and third switch port P 43 of four-way valve 4 and then in order of first heat exchanger 10 , expansion device 3 , second heat exchanger 20 , and gas-liquid separator 6 .
  • the liquid refrigerant discharged from liquid discharge port P 63 of gas-liquid separator 6 flows from fourth port P 4 into third heat exchanger 30 .
  • the gaseous refrigerant discharged from gas discharge port P 62 of gas-liquid separator 6 flows through first flow rate control device 51 toward first junction point a shown in FIG. 2 .
  • the refrigerant discharged from third port P 3 of third heat exchanger 30 also flows into first junction point a.
  • the refrigerant after joining at first junction point a from two directions flows through four-way valve 4 into the inlet port of compressor 1 .
  • the first route of the refrigerant in the first operation mode is formed by the route of the refrigerant outlined.
  • the refrigerant flows in order of compressor 1 , first heat exchanger 10 , expansion device 3 , second heat exchanger 20 , and gas-liquid separator 6 , and then, the refrigerant in liquid state discharged from gas-liquid separator 6 flows into third heat exchanger 30 , whereas the refrigerant in gaseous state discharged from gas-liquid separator 6 joins, through first flow rate control device 51 , the refrigerant discharged from third heat exchanger 30 at first junction point a.
  • the refrigerant after joining at first junction point a flows to compressor 1 .
  • first heat exchanger 10 on the indoor unit side functions as a condenser
  • second heat exchanger 20 and third heat exchanger 30 on the outdoor unit side function as an evaporator.
  • High-temperature, high-pressure gaseous refrigerant discharged from compressor 1 flows through four-way valve 4 and then into first heat exchanger 10 on the indoor unit side.
  • the gaseous refrigerant that has flowed into first heat exchanger 10 condenses by heat dissipation to the indoor air. As a result, liquefaction of the refrigerant advances in first heat exchanger 10 .
  • the refrigerant discharged from first heat exchanger 10 flows into expansion device 3 .
  • Expansion device 3 includes a valve for adjusting a degree of expansion of the refrigerant.
  • the refrigerant discharged from first heat exchanger 10 expands in expansion device 3 to turn into two-phase refrigerant that is a mixture of gas and liquid.
  • the two-phase refrigerant discharged from expansion device 3 flows through third check valve 43 from first port P 1 to second heat exchanger 20 on the outdoor unit side.
  • a flow of the refrigerant from expansion device 3 toward second junction point b is interrupted by fourth check valve 44 .
  • the two-phase refrigerant Since the two-phase refrigerant partly evaporates in second heat exchanger 20 , the two-phase refrigerant with an increased dryness fraction is discharged from second port P 2 of second heat exchanger 20 .
  • the two-phase refrigerant discharged from second port P 2 flows from inflow port P 61 into gas-liquid separator 6 to be separated into gaseous refrigerant and liquid refrigerant.
  • the liquid refrigerant separated in gas-liquid separator 6 is discharged from liquid discharge port P 63 .
  • the liquid refrigerant discharged from liquid discharge port P 63 flows from fourth port P 4 into third heat exchanger 30 .
  • the liquid refrigerant discharged from liquid discharge port P 63 does not flow through fourth check valve 44 to the expansion device 3 side. This is because the pressure of the liquid refrigerant discharged from liquid discharge port P 63 is lower than the pressure of the refrigerant that flows from expansion device 3 toward third check valve 43 .
  • the pressure difference therebetween corresponds to the amount of pressure loss between second heat exchanger 20 and third check valve 43 .
  • Third temperature sensor 73 detects the temperature of the liquid refrigerant that flows from fourth port P 4 into third heat exchanger 30 . The temperature detected by third temperature sensor 73 is transmitted to controller 90 .
  • the gaseous refrigerant separated in gas-liquid separator 6 is discharged from gas discharge port P 62 .
  • the gaseous refrigerant discharged from gas discharge port P 62 flows through first flow rate control device 51 toward first junction point a on the downstream side of third heat exchanger 30 without flowing into third heat exchanger 30 .
  • the liquid refrigerant flows, and the gaseous refrigerant does not flow, into third heat exchanger 30 on the downstream side.
  • First temperature sensor 71 detects the temperature of the gaseous refrigerant separated in gas-liquid separator 6 .
  • the temperature detected by first temperature sensor 71 is transmitted to controller 90 .
  • This temperature is equivalent to the saturated gas temperature of the refrigerant that has flowed into gas-liquid separator 6 .
  • Controller 90 estimates the pressure in gas-liquid separator 6 from the temperature detected by first temperature sensor 71 .
  • third heat exchanger 30 the liquid refrigerant is subjected to heat exchange with the outside air to be gasified.
  • the gaseous refrigerant does not flow into third heat exchanger 30 , a temperature gradient does not occur in third heat exchanger 30 . Consequently, a temperature imbalance does not occur in third heat exchanger 30 .
  • the refrigerant gasified in third heat exchanger 30 is discharged from third port P 3 .
  • Second temperature sensor 72 detects the temperature of the gaseous refrigerant discharged from third port P 3 .
  • the temperature detected by second temperature sensor 72 is transmitted to controller 90 .
  • the temperature detected by second temperature sensor 72 corresponds to the temperature at the outlet of the evaporator in the first operation mode.
  • Controller 90 estimates a degree of superheat (SH) at the outlet of the evaporator based on the temperature detected by first temperature sensor 71 and the temperature detected by second temperature sensor 72 .
  • SH degree of superheat
  • the gaseous refrigerant discharged from third port P 3 of third heat exchanger 30 joins the gaseous refrigerant discharged from first flow rate control device 51 at first junction point a.
  • the gaseous refrigerant after joining from two directions flows through first check valve 41 and four-way valve 4 into the inlet side of compressor 1 .
  • the gaseous refrigerant does not flow through second check valve 42 to second heat exchanger 20 .
  • the pressure of the gaseous refrigerant between first check valve 41 and four-way valve 4 is lower than the pressure of the refrigerant at first port P 1 of second heat exchanger 20 .
  • the pressure difference therebetween corresponds to the amount of pressure loss between second heat exchanger 20 and first check valve 41 .
  • FIG. 3 shows a refrigerant flow in the second operation mode of refrigeration cycle apparatus 100 .
  • the refrigerant flow in the second operation mode will be described with reference to FIG. 3 .
  • controller 90 controls four-way valve 4 such that the flow path indicated by the solid line in FIG. 3 is formed in four-way valve 4 .
  • the refrigerant flows through the refrigerant circuit of refrigeration cycle apparatus 100 , as indicated by the arrows, by the action of switch device 40 including four-way valve 4 .
  • the refrigerant discharged from compressor 1 flows through first switch port P 41 and fourth switch port P 44 of four-way valve 4 , and then in order of second heat exchanger 20 and gas-liquid separator 6 .
  • the gaseous refrigerant discharged from gas discharge port P 62 of gas-liquid separator 6 flows through first flow rate control device 51 from third port P 3 into third heat exchanger 30 .
  • liquid refrigerant discharged from liquid discharge port P 63 of gas-liquid separator 6 joins the refrigerant discharged from fourth port P 4 of third heat exchanger 30 at second junction point b.
  • the refrigerant after joining at second junction point b flows in order of expansion device 3 and first heat exchanger 10 , and then flows through four-way valve 4 into the inlet port of compressor 1 .
  • the second route of the refrigerant in the second operation mode is formed by the route of the refrigerant outlined.
  • the refrigerant flows in order of compressor 1 , second heat exchanger 20 , and gas-liquid separator 6 , and the refrigerant in gaseous state discharged from gas-liquid separator 6 flows through first flow rate control device 51 into third heat exchanger 30 , whereas the refrigerant in liquid state discharged from gas-liquid separator 6 joins the refrigerant discharged from third heat exchanger 30 at second junction point b, and the refrigerant after joining at second junction point b flows in order of expansion device 3 , first heat exchanger 10 , and compressor 1 .
  • first heat exchanger 10 on the indoor unit side functions as an evaporator
  • second heat exchanger 20 and third heat exchanger 30 on the outdoor unit side function as a condenser.
  • High-temperature, high-pressure gaseous refrigerant discharged from compressor 1 flows through four-way valve 4 , and then flows through second check valve 42 from first port P 1 into second heat exchanger 20 on the outdoor unit side.
  • a flow of the refrigerant from four-way valve 4 toward first junction point a is interrupted by first check valve 41 .
  • the gaseous refrigerant that has flowed into second heat exchanger 20 condenses by heat dissipation to the outside air to turn into two-phase refrigerant that is a mixture of gas and liquid.
  • the two-phase refrigerant discharged from the second port of second heat exchanger 20 flows from inflow port P 61 into gas-liquid separator 6 to be separated into gaseous refrigerant and liquid refrigerant.
  • the gaseous refrigerant separated in gas-liquid separator 6 is discharged from gas discharge port P 62 .
  • the gaseous refrigerant discharged from gas discharge port P 62 flows through first flow rate control device 51 from third port P 3 into third heat exchanger 30 .
  • the gaseous refrigerant discharged from first flow rate control device 51 does not flow through first check valve 41 to the fourth switch port P 44 side of four-way valve 4 .
  • the pressure difference therebetween is equivalent to the amount of pressure loss between four-way valve 4 and first check valve 41 .
  • liquid refrigerant separated in gas-liquid separator 6 is discharged from liquid discharge port P 63 .
  • the liquid refrigerant discharged from liquid discharge port P 63 flows downstream of third heat exchanger 30 without flowing into third heat exchanger 30 .
  • the gaseous refrigerant flows, and the liquid refrigerant does not flow, into third heat exchanger 30 on the downstream side.
  • third heat exchanger 30 the gaseous refrigerant is subjected to heat exchange with the outside air to be condensed. As a result, the liquefaction of the refrigerant advances in third heat exchanger 30 . Thus, since the liquid refrigerant does not flow into third heat exchanger 30 , a temperature gradient does not occur in third heat exchanger 30 . Consequently, a temperature imbalance does not occur in third heat exchanger 30 .
  • the liquid refrigerant discharged from fourth port P 4 of third heat exchanger 30 joins the liquid refrigerant discharged from liquid discharge port P 63 of gas-liquid separator 6 at second junction point b.
  • the liquid refrigerant after joining at second junction point b flows through fourth check valve 44 into expansion device 3 .
  • the liquid refrigerant does not flow through third check valve 43 to second heat exchanger 20 .
  • the pressure of the refrigerant at fourth check valve 44 is lower than the pressure of the refrigerant at first port P 1 of second heat exchanger 20 .
  • the pressure difference therebetween is equivalent to the amount of pressure loss among second heat exchanger 20 , first flow rate control device 51 , and fourth check valve 44 .
  • the refrigerant that has flowed into expansion device 3 is expanded by expansion device 3 , and then flows into first heat exchanger 10 on the indoor unit side.
  • the refrigerant that has flowed into first heat exchanger 10 evaporates by heat absorption from the indoor air, and then flows through four-way valve 4 into the inlet side of compressor 1 .
  • first check valve 41 and second check valve 42 constitute a first valve mechanism.
  • Third check valve 43 and fourth check valve 44 constitute a second valve mechanism.
  • the first valve mechanism causes expansion device 3 to communicate with first port P 1 of second heat exchanger 20 and interrupts the communication between expansion device 3 and fourth port P 4 of third heat exchanger 30 .
  • the first valve mechanism opens a flow of the refrigerant from first junction point a to fourth switch port P 44 and interrupts a flow of the refrigerant from expansion device 3 to fourth switch port P 44 .
  • the first valve mechanism opens a flow of the refrigerant from fourth switch port P 44 to second heat exchanger 20 and interrupts a flow of the refrigerant from fourth switch port P 44 to first junction point a.
  • the second valve mechanism opens a flow of the refrigerant from expansion device 3 to second heat exchanger 20 and interrupts a flow of the refrigerant from expansion device 3 to second junction point b in the first operation mode, and opens a flow of the refrigerant from second junction point b to expansion device 3 and interrupts a flow of the refrigerant from fourth switch port P 44 to expansion device 3 in the second operation mode.
  • FIG. 4 is a p-h diagram showing changes in the state of refrigerant in the first operation mode. FIG. 4 will be described with reference to FIG. 2 .
  • hout, hout′, hg, hl, hin, and hsep in FIG. 4 correspond to Poout, Poout′, Pog, Pol, Poin, and Posep in FIG. 2 , respectively.
  • the enthalpy at a position Poin of the refrigerant circuit in FIG. 2 corresponds to hin shown in FIG. 4 .
  • High-temperature, high-pressure gaseous refrigerant discharged from compressor 1 is condensed by first heat exchanger 10 . Subsequently, the refrigerant is separated into two phases, that is, gaseous refrigerant and liquid refrigerant, in expansion device 3 , and then flows into second heat exchanger 20 . The enthalpy of the refrigerant at this time is hin. The two-phase refrigerant with a higher dryness fraction is discharged from second heat exchanger 20 . The discharged two-phase refrigerant flows into gas-liquid separator 6 . The enthalpy of the refrigerant at this time is hsep.
  • the two-phase refrigerant that has flowed into gas-liquid separator 6 is separated into gaseous refrigerant and liquid refrigerant in gas-liquid separator 6 .
  • the gaseous refrigerant discharged from gas-liquid separator 6 flows toward first flow rate control device 51 .
  • the enthalpy of the gaseous refrigerant at this time is hg.
  • the liquid refrigerant discharged from gas-liquid separator 6 flows toward third heat exchanger 30 .
  • the enthalpy of the liquid refrigerant at this time is hl.
  • Equation (1) evaporation capacity
  • a flow rate X depends on the rotation speed of compressor 1 , the density of the refrigerant suctioned into compressor 1 , and the like.
  • a flow rate Y and a flow rate Z depend on the degree of opening of first flow rate control device 51 attached to the gaseous refrigerant outlet side of gas-liquid separator 6 .
  • An enthalpy hsep of the refrigerant that flows into gas-liquid separator 6 can be adjusted by the size, air volume, and the like of second heat exchanger 20 that functions as an evaporator.
  • evaporation capacity can be improved by adjusting the degree of opening of first flow rate control device 51 while taking into account changes in the composition of the refrigerant.
  • the liquid refrigerant that has flowed into third heat exchanger 30 is subjected to heat exchange with the outside air to be gasified. Consequently, the enthalpy of the refrigerant discharged from third heat exchanger 30 is hout′.
  • the gaseous refrigerant discharged from third heat exchanger 30 joins the gaseous refrigerant discharged from first flow rate control device 51 at first junction point a.
  • the enthalpy of the gaseous refrigerant at this time is hout. Subsequently, the gaseous refrigerant flows through four-way valve 4 back to compressor 1 .
  • a pressure loss can be reduced compared with the case where the total amount of two-phase refrigerant is flowed to third heat exchanger 30 .
  • third heat exchanger 30 since only the liquid refrigerant having a higher density than that of the gaseous refrigerant is flowed to third heat exchanger 30 , the dryness fraction at the inlet of third heat exchanger 30 is almost zero. Thus, the flow rate of the refrigerant that flows through third heat exchanger 30 can be reduced compared with the case where two-phase refrigerant is flowed. As a result, a pressure loss can be reduced also in terms of flow rate.
  • third heat exchanger 30 On the downstream side.
  • the gaseous refrigerant flows through a flow path at a relatively high position
  • the liquid refrigerant flows through a flow path at a relatively low position.
  • an imbalance occurs in the refrigerant temperature due to the temperature gradient of the zeotropic refrigerant mixture.
  • liquid refrigerant having an almost zero dryness fraction is flowed to third heat exchanger 30 .
  • Such liquid refrigerant is insusceptible to gravity or a flow imbalance.
  • the flow rate of the refrigerant in each flow path can be made uniform as only the liquid refrigerant is flowed to third heat exchanger 30 .
  • the present embodiment can reduce an imbalance in the refrigerant temperature due to a temperature gradient.
  • the present embodiment can control the amount of the liquid refrigerant that flows through third heat exchanger 30 by adjusting the degree of opening of first flow rate control device 51 .
  • the degree of opening of first flow rate control device 51 is increased with the rotation speed of compressor 1 and the degree of opening of expansion device 3 being kept constant, the amount of the gaseous refrigerant that is bypassed to the outlet side of third heat exchanger 30 that functions as an evaporator increases, and the amount of liquid refrigerant that flows through third heat exchanger 30 decreases.
  • the degree of superheat at the outlet of third heat exchanger 30 increases. Contrastingly, as the degree of opening of first flow rate control device 51 is reduced, the amount of the liquid refrigerant that flows into third heat exchanger 30 increases, so that the liquid refrigerant will not entirely gasify within third heat exchanger 30 . As a result, the degree of superheat decreases. Thus, the degree of superheat at the outlet portion of third heat exchanger 30 can be controlled to an optimum value by adjusting the degree of opening of first flow rate control device 51 to increase or decrease the amount of gaseous refrigerant to be bypassed.
  • the degree of superheat at the outlet portion of third heat exchanger 30 can be estimated based on the temperature detected by first temperature sensor 71 and the temperature detected by second temperature sensor 72 . It is difficult to estimate a saturation temperature from the temperature of the refrigerant in two-phase state because the zeotropic refrigerant mixture has a temperature gradient, but the degree of superheat can be estimated more accurately based on the temperature of the gaseous refrigerant brought to a single-phase state by gas-liquid separator 6 .
  • FIG. 5 is a p-h diagram showing changes in the state of refrigerant in the second operation mode. FIG. 5 will be described with reference to FIG. 3 .
  • hout, hout′, hg, hl, hin, and hsep in FIG. 5 correspond to Poout, Poout′, Pog, Pol, Poin, and Posep in FIG. 3 , respectively.
  • the enthalpy of the refrigerant at this time is hin.
  • the refrigerant that has flowed into second heat exchanger 20 condenses to turn into two-phase refrigerant, and is then discharged.
  • the two-phase refrigerant discharged from second heat exchanger 20 flows into gas-liquid separator 6 .
  • the enthalpy of the refrigerant at this time is hsep.
  • the two-phase refrigerant that has flowed into gas-liquid separator 6 is separated into gaseous refrigerant and liquid refrigerant in gas-liquid separator 6 .
  • the gaseous refrigerant discharged from gas-liquid separator 6 flows through first flow rate control device 51 toward third heat exchanger 30 .
  • the enthalpy of the gaseous refrigerant upstream of first flow rate control device 51 is hg.
  • the liquid refrigerant discharged from gas-liquid separator 6 flows downstream of third heat exchanger 30 .
  • the enthalpy of the liquid refrigerant at this time is hl.
  • condensation capacity is expressed by Equation (2) below.
  • the gaseous refrigerant that has flowed into third heat exchanger 30 is subjected to heat exchange with the outside air to be condensed.
  • the enthalpy of the refrigerant discharged from third heat exchanger 30 is hout′.
  • the refrigerant discharged from third heat exchanger 30 joins the liquid refrigerant discharged from gas-liquid separator 6 at second junction point b.
  • the enthalpy of the refrigerant at this time is hout.
  • the refrigerant expands in expansion device 3 , flows into first heat exchanger 10 , evaporates, and then flows through four-way valve 4 back to compressor 1 .
  • the flow rate of the refrigerant that flows to third heat exchanger 30 can be reduced compared with the case where the total amount of the two-phase refrigerant including gaseous refrigerant and liquid refrigerant is flowed to third heat exchanger 30 .
  • a pressure loss can be reduced compared with the case where the total amount of the two-phase refrigerant is flowed to third heat exchanger 30 .
  • the second operation mode when the zeotropic refrigerant mixture flows into second heat exchanger 20 on the outdoor unit side, refrigerant having a higher boiling point is condensed preferentially in second heat exchanger 20 over refrigerant having a lower boiling point.
  • the gaseous refrigerant in gas-liquid separator 6 is mostly refrigerant containing low-boiling components
  • the liquid refrigerant in gas-liquid separator 6 is mostly refrigerant having a high boiling point.
  • the second operation mode since only the gaseous refrigerant separated in gas-liquid separator 6 is flowed to third heat exchanger 30 , it is refrigerant containing low-boiling components that is condensed in third heat exchanger 30 .
  • gas-liquid separator 6 allows refrigerant containing more low-boiling components to flow to third heat exchanger 30 on the downstream side, of second heat exchanger 20 and third heat exchanger 30 .
  • the efficiency of the refrigeration cycle can be improved.
  • the amount of the refrigerant that flows to third heat exchanger 30 can be adjusted by adjusting the degree of opening of first flow rate control device 51 while taking into account changes in the composition of the refrigerant, as in the first operation mode. For example, when the degree of opening of first flow rate control device 51 is increased with the rotation speed of compressor 1 and the degree of opening of expansion device 3 being kept constant, the amount of gaseous refrigerant that flows into third heat exchanger 30 increases.
  • the degree of supercool at the outlet portion of third heat exchanger 30 can be estimated based on the temperature detected by first temperature sensor 71 and the temperature detected by third temperature sensor 73 .
  • FIG. 6 is a flowchart for describing control of controller 90 in the first operation mode.
  • controller 90 changes the rotation speed of compressor 1 (step S 1 ).
  • the rotation speed of compressor 1 is determined according to, for example, a difference between the indoor temperature and the temperature set with a remote control for the indoor unit.
  • Controller 90 changes the rotation speed of compressor 1 to an appropriate value.
  • Controller 90 then adjusts the degree of opening of expansion device 3 (step S 2 ).
  • Controller 90 then calculates the degree of supercool (SC) at the outlet of first heat exchanger 10 that functions as a condenser (step S 3 ).
  • the degree of supercool at the outlet of first heat exchanger 10 can be calculated from, for example, the temperature at the outlet of first heat exchanger 10 and the pressure of first heat exchanger 10 .
  • a sensor that detects temperature and a sensor that detects pressure can be disposed in the refrigerant circuit as appropriate.
  • Controller 90 determines whether the degree of supercool at the outlet of first heat exchanger 10 that functions as a condenser is within a target range (step S 4 ). When determining that the degree of supercool at the outlet of first heat exchanger 10 is not within the target range, controller 90 adjusts the degree of opening of expansion device 3 again in step S 2 .
  • controller 90 repeatedly adjusts the degree of opening of expansion device 3 in step S 2 until the degree of supercool at the outlet of first heat exchanger 10 falls within the target range that is set for every rotation speed of compressor 1 .
  • the target range is a target value ⁇ a target error.
  • controller 90 adjusts the degree of opening of first flow rate control device 51 (step S 5 ).
  • Controller 90 then calculates the degree of superheat (SH) at the outlet of third heat exchanger 30 that functions as an evaporator (step S 6 ). At this time, controller 90 calculates the degree of superheat at the outlet portion of third heat exchanger 30 based on the temperature detected by first temperature sensor 71 and the temperature detected by second temperature sensor 72 .
  • Controller 90 determines whether the degree of superheat at the outlet of third heat exchanger 30 that functions as an evaporator is within the target range (step S 7 ). When determining that the degree of superheat at the outlet of third heat exchanger 30 is not within the target value, controller 90 adjusts the degree of opening of first flow rate control device 51 again in step S 5 .
  • controller 90 repeatedly adjusts the degree of opening of first flow rate control device 51 in step S 5 until the degree of superheat at the outlet of third heat exchanger 30 falls within the target range that is set for every rotation speed of compressor 1 .
  • controller 90 ends the process.
  • controller 90 may set the degree of opening of first flow rate control device 51 to zero to block the flow path, thereby allowing the gaseous refrigerant to flow to third heat exchanger 30 . In this case, controller 90 checks whether the rotation speed of compressor 1 is within the prescribed rotation speed range every time the rotation speed of compressor 1 changes.
  • controller 90 calculates the degree of superheat of third heat exchanger 30 based on a detected value of first temperature sensor 71 and a detected value of second temperature sensor 72 and adjusts the degree of opening of first flow rate control device 51 , thereby controlling the degree of superheat of third heat exchanger 30 .
  • FIG. 7 is a flowchart for describing control of controller 90 in the second operation mode.
  • controller 90 changes the rotation speed of compressor 1 as in the process of step S 1 (step S 11 ).
  • controller 90 adjusts the degree of opening of expansion device 3 such that the discharge temperature of compressor 1 is within the target range (step S 12 ).
  • the discharge temperature of compressor 1 can be specified based on, for example, a detected value of the temperature sensor provided at the discharge portion of compressor 1 .
  • Controller 90 determines whether the discharge temperature of compressor 1 is within the target range (step S 13 ). When determining that the discharge temperature of compressor 1 is not within the target range, controller 90 adjusts the degree of opening of expansion device 3 again in step S 12 .
  • controller 90 adjusts the degree of opening of first flow rate control device 51 (step S 14 ).
  • Controller 90 then calculates the degree of supercool at the outlet of third heat exchanger 30 that functions as a condenser (step S 15 ). At this time, controller 90 calculates the degree of supercool at the outlet portion of third heat exchanger 30 based on the temperature detected by first temperature sensor 71 and the temperature detected by third temperature sensor 73 .
  • Controller 90 determines whether the degree of supercool at the outlet of third heat exchanger 30 that functions as a condenser is within the target range that is set for every rotation speed of compressor 1 (step S 16 ). When determining that the degree of supercool at the outlet of third heat exchanger 30 is not within the target range, controller 90 adjusts the degree of opening of first flow rate control device 51 again in step S 14 .
  • controller 90 repeatedly adjusts the degree of opening of first flow rate control device 51 in step S 14 until the degree of supercool at the outlet of third heat exchanger 30 falls within the target range that is set for every rotation speed of compressor 1 .
  • controller 90 ends the process.
  • controller 90 calculates the degree of supercool of third heat exchanger 30 based on the detected value of first temperature sensor 71 and the detected value of third temperature sensor 73 and adjusts the degree of opening of first flow rate control device 51 , thereby controlling the degree of supercool of third heat exchanger 30 .
  • refrigeration cycle apparatus 100 has operation capability improved by flowing liquid refrigerant or gaseous refrigerant to third heat exchanger 30 on the downstream side according to its operation mode.
  • Refrigeration cycle apparatus 100 can thus have improved efficiency of operating a refrigeration cycle in either the first operation mode or the second operation mode.
  • refrigeration cycle apparatus 100 can have operating efficiency improved with the use of gas-liquid separator 6 when second heat exchanger 20 and third heat exchanger 30 on the outdoor unit side are caused to function as either an evaporator or a condenser.
  • the effect of improving the efficiency of operating a refrigeration cycle can be improved when a zeotropic refrigerant mixture is used.
  • FIG. 8 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus 110 according to Embodiment 2.
  • Refrigeration cycle apparatus 110 according to Embodiment 2 is different from refrigeration cycle apparatus 100 according to Embodiment 1 in the configuration of the switch device.
  • Refrigeration cycle apparatus 110 according to Embodiment 2 includes a switch device 400 composed of a first three-way valve 45 and a second three-way valve 46 .
  • First three-way valve 45 is provided among fourth switch port P 44 , second heat exchanger 20 , and first junction point a. First three-way valve 45 switches a target to be connected to fourth switch port P 44 between second heat exchanger 20 and first junction point a.
  • Second three-way valve 46 is provided among expansion device 3 , second heat exchanger 20 , and second junction point b. Second three-way valve 46 switches a target to be connected to expansion device 3 between second heat exchanger 20 and second junction point b.
  • Controller 90 controls four-way valve 4 , first three-way valve 45 , and second three-way valve 46 such that the flow path indicated by the solid line in FIG. 8 is formed in the first operation mode.
  • the refrigerant circulates through the refrigerant circuit in the same order as the order shown in FIG. 2 .
  • controller 90 controls four-way valve 4 as shown in FIG. 3 and also switches the manner of connection of first three-way valve 45 and second three-way valve 46 to the manner indicated by the broken line in FIG. 8 .
  • the refrigerant circulates through the refrigerant circuit in the same order as the order shown in FIG. 3 .
  • First three-way valve 45 functions similarly to first check valve 41 and second check valve 42 of refrigeration cycle apparatus 100 according to Embodiment 1.
  • Second three-way valve 46 functions similarly to third check valve 43 and fourth check valve 44 of refrigeration cycle apparatus 100 according of Embodiment 1.
  • the first valve mechanism includes first three-way valve 45
  • the second valve mechanism includes second three-way valve 46 .
  • the first valve mechanism according to Embodiment 1 includes first check valve 41 and second check valve 42 .
  • the first valve mechanism according to Embodiment 2 includes first three-way valve 45 .
  • the second valve mechanism according to Embodiment 1 includes third check valve 43 and fourth check valve 44 .
  • the second valve mechanism according to Embodiment 2 includes second three-way valve 46 .
  • Embodiment 2 can thus reduce the number of components compared with Embodiment 1.
  • FIG. 9 is a refrigerant circuit diagram showing a configuration of a refrigeration cycle apparatus 120 according to Embodiment 3. Compared with refrigeration cycle apparatus 100 according to Embodiment 1, refrigeration cycle apparatus 120 according to Embodiment 3 further includes a second flow rate control device 52 and a fourth temperature sensor 74 .
  • Second flow rate control device 52 is provided between second junction point b and the side of gas-liquid separator 6 on which the refrigerant in liquid state is discharged.
  • Fourth temperature sensor 74 is provided between second flow rate control device 52 and the side of gas-liquid separator 6 on which liquid refrigerant is discharged.
  • controller 90 can more finely adjust the amount of gaseous refrigerant and the amount of liquid refrigerant discharged from gas-liquid separator 6 .
  • first temperature sensor 71 since the detection target of first temperature sensor 71 is a temperature of gaseous refrigerant, the temperature gradient of the zeotropic refrigerant mixture needs to be taken into account when the saturation temperature of liquid refrigerant is calculated using a detected value of first temperature sensor 71 .
  • the saturation temperature of the liquid refrigerant can be directly detected with fourth temperature sensor 74 . This allows controller 90 to more accurately calculate a degree of supercool based on a detected value of third temperature sensor 73 and a detected value of fourth temperature sensor 74 .
  • FIG. 10 is a flowchart for describing control of controller 90 in the second operation mode according to Embodiment 3.
  • the flowchart shown in FIG. 10 is different from the flowchart shown in FIG. 7 only in that step S 24 is provided in place of step S 14 .
  • steps S 21 to S 23 in FIG. 10 are the same as the processes of steps S 11 to S 13 in FIG. 7 , description of which will not be repeated.
  • step S 24 controller 90 adjusts the degrees of opening of first flow rate control device 51 and second flow rate control device 52 .
  • Controller 90 then calculates the degree of supercool at the outlet of third heat exchanger 30 that functions as a condenser (step S 25 ). At this time, controller 90 calculates the degree of supercool at the outlet portion of third heat exchanger 30 based on the temperature detected by third temperature sensor 73 and the temperature detected by fourth temperature sensor 74 . Thus, controller 90 can more accurately calculate a degree of supercool than when calculating the degree of supercool at the outlet portion of third heat exchanger 30 based on the temperature detected by first temperature sensor 71 and the temperature detected by third temperature sensor 73 .
  • Controller 90 determines whether the degree of supercool at the outlet of third heat exchanger 30 that functions as a condenser is within the target range that is set for every rotation speed of compressor 1 (step S 26 ). When determining that the degree of supercool at the outlet of third heat exchanger 30 is not within the target range, controller 90 adjusts the degrees of opening of first flow rate control device 51 and second flow rate control device 52 again in step S 24 .
  • controller 90 repeatedly adjusts the degrees of opening of first flow rate control device 51 and second flow rate control device 52 in step S 24 until the degree of supercool at the outlet of third heat exchanger 30 falls within the target range that is set for every rotation speed of compressor 1 .
  • controller 90 ends the process.
  • the first valve mechanism includes first check valve 41 and second check valve 42
  • the second valve mechanism includes third check valve 43 and fourth check valve 44
  • the first valve mechanism may include first three-way valve 45
  • the second valve mechanism may include second three-way valve 46 .
  • refrigerant flows in order of the compressor ( 1 ), the first heat exchanger ( 10 ), the expansion device ( 3 ), the second heat exchanger ( 20 ), and the gas-liquid separator ( 6 ), and then, the refrigerant in liquid state discharged from the gas-liquid separator ( 6 ) flows into the third heat exchanger ( 30 ), and the refrigerant in gaseous state discharged from the gas-liquid separator ( 6 ) joins, through the first flow rate control device ( 51 ), the refrigerant discharged from the third heat exchanger ( 30 ) at a first junction point (a). The refrigerant after joining at the first junction point (a) flows to the compressor ( 1 ).
  • the refrigerant flows in order of the compressor ( 1 ), the second heat exchanger ( 20 ), and the gas-liquid separator ( 6 ), the refrigerant in gaseous state discharged from the gas-liquid separator ( 6 ) flows through the first flow rate control device ( 51 ) into the third heat exchanger ( 30 ), the refrigerant in liquid state discharged from the gas-liquid separator ( 6 ) joins the refrigerant discharged from the third heat exchanger ( 30 ) at a second junction point (b), and the refrigerant after joining at the second junction point (b) flows in order of the expansion device ( 3 ), the first heat exchanger ( 10 ), and the compressor ( 1 ).
  • the efficiency of operating a refrigeration cycle can be improved in either the first operation mode or the second operation mode.
  • the operating efficiency can be improved with the gas-liquid separator when the heat exchanger is caused to function as either an evaporator or a condenser.
  • the efficiency of operating a refrigeration cycle can be improved when a zeotropic refrigerant mixture is used.
  • the switch device ( 40 ) includes a four-way valve ( 4 ), a first valve mechanism ( 41 , 42 ), and a second valve mechanism ( 43 , 44 ).
  • the four-way valve ( 4 ) has a first switch port (P 41 ), a second switch port (P 42 ), a third switch port (P 43 ), and a fourth switch port (P 44 ), an outlet port of the compressor ( 1 ) is connected to the first switch port (P 41 ), and an inlet port of the compressor ( 1 ) is connected to the second switch port (P 42 ).
  • the four-way valve ( 4 ) is configured to, in the first operation mode, cause the first switch port (P 41 ) to communicate with the third switch port (P 43 ) and cause the second switch port (P 42 ) to communicate with the fourth switch port (P 44 ), and in the second operation mode, cause the first switch port (P 41 ) to communicate with the fourth switch port (P 44 ) and cause the second switch port (P 42 ) to communicate with the third switch port (P 43 ).
  • the first valve mechanism ( 41 , 42 ) is configured to, in the first operation mode, open a flow of the refrigerant from the first junction point (a) to the fourth switch port (P 44 ) and interrupt a flow of the refrigerant from the expansion device ( 3 ) to the fourth switch port (P 44 ), and in the second operation mode, open a flow of the refrigerant from the fourth switch port (P 44 ) to the second heat exchanger ( 20 ) and interrupt a flow of the refrigerant from the fourth switch port (P 44 ) to the first junction point (a).
  • the second valve mechanism ( 43 , 44 ) is configured to, in the first operation mode, open a flow of the refrigerant from the expansion device ( 3 ) to the second heat exchanger ( 20 ) and interrupt a flow of the refrigerant from the expansion device ( 3 ) to the second junction point (b), and in the second operation mode, open a flow of the refrigerant from the second junction point (b) to the expansion device ( 3 ) and interrupt a flow of the refrigerant from the fourth switch port (P 44 ) to the expansion device ( 3 ).
  • the first valve mechanism ( 41 , 42 ) includes a first check valve ( 41 ) provided between the fourth switch port (P 44 ) and the first junction point (a) and configured to interrupt a flow of the refrigerant from the fourth switch port (P 44 ) toward a first junction point (a), and a second check valve ( 42 ) provided among the expansion device ( 3 ), the fourth switch port (P 44 ), and the second heat exchanger ( 20 ) and configured to interrupt a flow of the refrigerant from the expansion device ( 3 ) to the fourth switch port (P 44 ).
  • the second valve mechanism ( 43 , 44 ) includes a third check valve ( 43 ) provided among the fourth switch port (P 44 ), the expansion device ( 3 ), and the second heat exchanger ( 20 ) and configured to interrupt a flow of the refrigerant from the fourth switch port (P 44 ) to the expansion device ( 3 ), and a fourth check valve ( 44 ) provided between the expansion device and the second junction point (b) and configured to interrupt a flow of the refrigerant from the expansion device ( 3 ) to the second junction point (b).
  • the first valve mechanism may include a first three-way valve ( 45 ).
  • the second valve mechanism may include a second three-way valve ( 46 ).
  • the first three-way valve ( 45 ) is provided among the fourth switch port (P 44 ), the second heat exchanger ( 20 ), and the first junction point (a) and is configured to switch a target to be connected to the fourth switch port (P 44 ) between the second heat exchanger ( 20 ) and the first junction point (a).
  • the second three-way valve ( 46 ) is provided among the expansion device ( 3 ), the second heat exchanger ( 20 ), and the second junction point (b) and is configured to switch a target to be connected to the expansion device ( 3 ) between the second heat exchanger ( 20 ) and the second junction point (b).
  • the refrigeration cycle apparatus further includes a first temperature sensor ( 71 ) provided between the first flow rate control device ( 51 ) and a side (P 62 ) of the gas-liquid separator ( 6 ) on which the refrigerant in gaseous state is discharged, a second temperature sensor ( 72 ) provided between the third heat exchanger ( 30 ) and the first junction point (a), and a controller ( 90 ) configured to control the first flow rate control device ( 51 ).
  • the controller ( 90 ) is configured to, in the first operation mode, calculate a degree of superheat of the third heat exchanger ( 30 ) based on a detected value of the first temperature sensor ( 71 ) and a detected value of the second temperature sensor ( 72 ) (step S 6 ) and adjust a degree of opening of the first flow rate control device ( 51 ) to control the degree of superheat of the third heat exchanger ( 30 ) (step S 5 to step S 7 ).
  • the refrigeration cycle apparatus may further include a third temperature sensor ( 73 ) provided between the third heat exchanger ( 30 ) and the second junction point (b).
  • the controller ( 90 ) is configured to, in the second operation mode, calculate a degree of supercool of the third heat exchanger ( 30 ) based on a detected value of the first temperature sensor ( 71 ) and a detected value of the third temperature sensor ( 73 ) (step S 15 ), and adjust the degree of opening of the first flow rate control device ( 51 ) to control the degree of supercool of the third heat exchanger ( 30 ) (step S 14 to step S 16 ).
  • the refrigeration cycle apparatus may further include a second flow rate control device ( 52 ) provided between the second junction point (b) and a side (P 63 ) of the gas-liquid separator ( 6 ) on which the refrigerant in liquid state is discharged, a third temperature sensor ( 73 ) provided between the third heat exchanger ( 30 ) and the second junction point (b), and a fourth temperature sensor ( 74 ) provided between the second flow rate control device ( 52 ) and a side (P 63 ) of the gas-liquid separator ( 6 ) on which the refrigerant in liquid state is discharged.
  • a second flow rate control device ( 52 ) provided between the second junction point (b) and a side (P 63 ) of the gas-liquid separator ( 6 ) on which the refrigerant in liquid state is discharged.
  • the controller ( 90 ) is configured to, in the second operation mode, calculate a degree of supercool of the third heat exchanger ( 30 ) based on a detected value of the third temperature sensor ( 73 ) and a detected value of the fourth temperature sensor ( 74 ) (step S 25 ), and adjust degrees of opening of the first flow rate control device ( 51 ) and the second flow rate control device ( 52 ) to control the degree of supercool of the third heat exchanger ( 30 ) (step S 24 to step S 26 ).

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
US18/263,405 2021-03-24 2021-03-24 Refrigeration cycle apparatus Abandoned US20240310092A1 (en)

Applications Claiming Priority (1)

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PCT/JP2021/012114 WO2022201336A1 (ja) 2021-03-24 2021-03-24 冷凍サイクル装置

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EP (1) EP4317847A4 (https=)
JP (1) JP7507963B2 (https=)
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WO (1) WO2022201336A1 (https=)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6225644U (https=) 1985-07-31 1987-02-17
JP2003106685A (ja) * 2001-09-28 2003-04-09 Mitsubishi Electric Corp 冷凍空調装置
JP4196873B2 (ja) * 2004-04-14 2008-12-17 株式会社デンソー エジェクタサイクル
JP7033967B2 (ja) * 2018-03-16 2022-03-11 三菱電機株式会社 冷凍サイクル装置
WO2021024443A1 (ja) * 2019-08-07 2021-02-11 三菱電機株式会社 冷凍サイクル装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JP H07-146019 (Year: 1995) *

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JP7507963B2 (ja) 2024-06-28
EP4317847A4 (en) 2024-05-01
JPWO2022201336A1 (https=) 2022-09-29
WO2022201336A1 (ja) 2022-09-29
CN116981894A (zh) 2023-10-31
EP4317847A1 (en) 2024-02-07

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