EP2765370A1 - Refrigeration cycle apparatus and hot water generator provided with the same - Google Patents

Refrigeration cycle apparatus and hot water generator provided with the same Download PDF

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Publication number
EP2765370A1
EP2765370A1 EP14152911.5A EP14152911A EP2765370A1 EP 2765370 A1 EP2765370 A1 EP 2765370A1 EP 14152911 A EP14152911 A EP 14152911A EP 2765370 A1 EP2765370 A1 EP 2765370A1
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EP
European Patent Office
Prior art keywords
refrigerant
evaporator
temperature
radiator
heat exchanger
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14152911.5A
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German (de)
English (en)
French (fr)
Inventor
Shunji Moriwaki
Shigeo Aoyama
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Panasonic Corp
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Panasonic Corp
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Filing date
Publication date
Application filed by Panasonic Corp filed Critical Panasonic Corp
Publication of EP2765370A1 publication Critical patent/EP2765370A1/en
Withdrawn legal-status Critical Current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
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B40/00—Subcoolers, desuperheaters or superheaters
    • F25B40/02—Subcoolers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02—Defrosting cycles
    • F25B47/022—Defrosting cycles hot gas defrosting
    • F25B47/025—Defrosting cycles hot gas defrosting by reversing the cycle
    • 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
    • F25B2339/00—Details of evaporators; Details of condensers
    • F25B2339/04—Details of condensers
    • F25B2339/047—Water-cooled condensers
    • 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
    • F25B2400/12—Inflammable refrigerants
    • 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
    • F25B2600/21—Refrigerant outlet evaporator temperature
    • 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
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a 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 invention relates to a refrigeration cycle apparatus using R32 as refrigerant, and to a hot water generator using the refrigeration cycle apparatus.
  • a supercooling heat exchanger is provided downstream of a radiator of a refrigerant circuit, and expanded refrigerant is made to flow into the supercooling heat exchanger, thereby supercooling the refrigerant which flows out from the radiator (see patent document 1 for example).
  • Fig. 9 shows the conventional refrigeration cycle apparatus described in patent document 1.
  • the refrigeration cycle apparatus 100 includes a refrigerant circuit 110 through which refrigerant circulates and a bypass passage 120.
  • the refrigerant circuit 110 is configured by annularly connecting a compressor 111, a radiator 112, a supercooling heat exchanger 113, a main expansion valve 114 and an evaporator 115 to one another through pipes.
  • the bypass passage 120 branches off from the refrigerant circuit 110 between the supercooling heat exchanger 113 and the main expansion valve 114, and is connected to the refrigerant circuit 110 between the evaporator 115 and the compressor 111 through the supercooling heat exchanger 113.
  • the bypass passage 120 is provided with a bypass expansion valve 121 upstream of the supercooling heat exchanger 113.
  • the supercooling heat exchanger 113 is configured so that a ratio of a heat exchange amount between refrigerant which is decompressed by the bypass expansion valve 121 in the supercooling heat exchanger 113 and refrigerant which flows out from the radiator 112 with respect to a heat exchange amount between refrigerant which flows into the radiator 112 and to-be heated fluid in the radiator 112 becomes 0.2 or more and 0.8 or less, when an opening degree of the bypass expansion valve 121 is adjusted such that dryness fraction of refrigerant which flows out from the supercooling heat exchanger 113 in the bypass passage 120 becomes 0.8 or more and less than 1.0.
  • R32 having low global warming potential is used as refrigerant which circulates through the refrigeration cycle apparatus, thereby realizing low global warming potential (see patent document 2 for example).
  • the evaporator is utilized with high heat exchanging efficiency.
  • the present invention has been accomplished to solve the problem of the conventional techniques, and it is an object of the invention to provide a refrigeration cycle apparatus which can efficiently be operated while suppressing excessive temperature rise of refrigerant discharged from a compressor even if refrigerant having a large specific heat ratio is used.
  • the present invention provides a refrigeration cycle apparatus comprising: a refrigerant circuit configured by annularly connecting a compressor, a radiator, a supercooling heat exchanger, a main expansion means and an evaporator to one another through refrigerant pipes; a bypass passage which branches off from the refrigerant circuit at a location between the radiator and the main expansion means and which extends through the supercooling heat exchanger to be connected to a compression chamber of the compressor or to the refrigerant circuit between the evaporator and the compressor; a bypass expansion means connected to an upstream side of the supercooling heat exchanger in the bypass passage; and a control device, wherein R32 is used as refrigerant which circulates through the refrigerant circuit, and the supercooling heat exchanger is configured so that a heat exchange ratio Qsc/Qc which is a ratio of a heat exchange amount Qsc between the refrigerant which is decompressed by the bypass expansion means and the refrigerant which flows out from the radiator in the supercooling heat exchange
  • a first aspect of the present invention provides a refrigeration cycle apparatus comprising: a refrigerant circuit configured by annularly connecting a compressor, a radiator, a supercooling heat exchanger, a main expansion means and an evaporator to one another through refrigerant pipes; a bypass passage which branches off from the refrigerant circuit at a location between the radiator and the main expansion means and extends through the supercooling heat exchanger to be connected to a compression chamber of the compressor or to the refrigerant circuit between the evaporator and the compressor; a bypass expansion means connected to an upstream side of the supercooling heat exchanger in the bypass passage; and a control device, wherein R32 is used as refrigerant which circulates through the refrigerant circuit, and the supercooling heat exchanger is configured so that a heat exchange ratio Qsc/Qc which is a ratio of a heat exchange amount Qsc between the refrigerant which is decompressed by the bypass expansion means and the refrigerant which flows out from the radiator in the supercool
  • the refrigerant dryness fraction at the outlet of the evaporator becomes 0.8 or more and less than 1.0 at which an evaporation heat-transfer coefficient becomes maximum and therefore, heat-transfer efficiency of the evaporator is enhanced.
  • the heat exchange ratio Qsc/Qc is set to 0.1 or more, a supercooling degree of refrigerant at the outlet of the supercooling heat exchanger is reliably increased, gas phase refrigerant which flows into the evaporator is reduced, and a pressure loss in a low pressure-side pipe of the refrigeration cycle is reduced.
  • the heat exchange ratio Qsc/Qc is set to 0.6 or less, the refrigerant dryness fraction at the outlet of the bypass passage is maintained in a low state.
  • the control device controls the main expansion means by a temperature difference between temperature of the refrigerant which flows into the evaporator and temperature of the refrigerant which flows out from the evaporator such that dryness fraction of the refrigerant which flows out from the evaporator becomes equal to 0.8 or more and less than 1.0.
  • the refrigerant dryness fraction at the outlet of the evaporator is controlled into an appropriate level in accordance with loads applied to the evaporator and a radiator. Therefore, in a wide operating range, it is possible to obtain an optimal driving state and thus, reliability and energy saving of the refrigeration cycle are enhanced.
  • the refrigeration cycle apparatus further comprises an evaporation temperature detecting means which detects evaporation temperature of the refrigerant in the evaporator, and when the evaporation temperature detecting means detects a decrease in the evaporation temperature, the control device controls the bypass expansion means such that the heat exchange ratio becomes greater.
  • the refrigeration cycle apparatus further comprises a condensation temperature detecting means which detects condensation temperature of the refrigerant in the radiator, and when the condensation temperature detecting means detects a decrease in the condensation temperature, the control device controls the bypass expansion means such that the heat exchange ratio becomes greater.
  • a hot water generator comprising the refrigeration cycle apparatus according to any one of the first to fourth aspects of the invention, the to-be heated fluid is water or antifreeze liquid, and the to-be heated fluid heated by the radiator is utilized for supplying hot water or for air heating.
  • heat exchanger which supplies hot water or heats a room using to-be heated fluid
  • heat exchanger is limited to a water/air heat exchanger or an antifreeze liquid/water heat exchanger. Therefore, heat medium which is heated by the radiator can widely be used for heating equipment (hot-air type heater, radiator, floor heating panel and the like), a water heater and the like, and the same effects as those of the first to fourth aspects of the invention can be obtained.
  • Fig. 1 is a schematic block diagram of a refrigeration cycle apparatus and a hot water generator according to the embodiment of the invention.
  • the refrigeration cycle apparatus 1A includes a refrigerant circuit 2 through which refrigerant circulates, a bypass passage 3 and a control device 4.
  • the refrigerant R32 which has low global warming potential is used.
  • the refrigerant circuit 2 is configured by annularly connecting a compressor 21, a radiator 22, a supercooling heat exchanger 23, a main expansion valve (main expansion means) 24 and an evaporator 25 to one another through refrigerant pipes.
  • a sub-accumulator 26 and a main accumulator 27 which separate gas and liquid from each other are provided between the evaporator 25 and the compressor 21.
  • the refrigerant circuit 2 is provided with a four-way valve 28 for switching between a normal operation for heating non-heated fluid at the radiator 22 and a defrosting operation for melting frost attached to the evaporator 25.
  • the refrigeration cycle apparatus 1A is used as heating means.
  • the hot water generator is configured.
  • the hot water generator can utilize hot water generated by the refrigeration cycle apparatus 1A for air heating. Hot water is produced in such a manner that the radiator 22 exchanges heat between refrigerant and water (to-be heated fluid). More specifically, a supply pipe 71 and a collecting pipe 72 are connected to the radiator 22, water is supplied to the radiator 22 through the supply pipe 71, and water (hot water) heated by the radiator 22 is collected through the collecting pipe 72. Water (hot water) collected through the collecting pipe 72 is sent to a heater such as a radiator directly or through a hot water tank and according to this, a room is heated and hot water is supplied.
  • a heater such as a radiator directly or through a hot water tank
  • the bypass passage 3 branches off from the refrigerant circuit 2 at a location between the supercooling heat exchanger 23 and the main expansion valve 24, and extends through the supercooling heat exchanger 23 to be connected to the refrigerant circuit 2 at a location between the evaporator 25 and the compressor 21.
  • the bypass passage 3 is connected to the refrigerant circuit 2 at a location between the sub-accumulator 26 and the main accumulator 27.
  • the bypass passage 3 is provided with a bypass expansion valve (bypass expansion means) 31 at a location upstream of the supercooling heat exchanger 23.
  • refrigerant discharged from the compressor 21 flows into the radiator 22 through the four-way valve 28.
  • refrigerant discharged from the compressor 21 is sent to the evaporator 25 through the four-way valve 28.
  • Arrows in Fig. 1 show a flowing direction of refrigerant at the time of normal operation. A state variation of refrigerant at the time of normal operation will be described below.
  • High pressure refrigerant discharged from the compressor 21 flows into the radiator 22 and dissipates heat to water which passes through the radiator 22.
  • the high pressure refrigerant which flows out from the radiator 22 flows into the supercooling heat exchanger 23, exchanges heat with low pressure refrigerant which is decompressed by a bypass expansion valve 31 and according to this, the refrigerant is supercooled.
  • the high pressure refrigerant which flows out from the supercooling heat exchanger 23 is shunted into the main expansion valve 24 and the bypass expansion valve 31.
  • the high pressure refrigerant which flowed into the main expansion valve 24 is decompressed by the main expansion valve 24 and expanded and then, the refrigerant flows into the evaporator 25.
  • the low pressure refrigerant which flowed into the evaporator 25 absorbs heat from air here.
  • High pressure refrigerant which flowed into the bypass expansion valve 31 is decompressed by the bypass expansion valve 31 and expanded and then, the refrigerant flows into the supercooling heat exchanger 23.
  • the low pressure refrigerant which flowed into the supercooling heat exchanger 23 is heated by the high pressure refrigerant which flowed out from the radiator 22. Thereafter, the low pressure refrigerant which flowed out from the supercooling heat exchanger 23 merges with the low pressure refrigerant which flowed out from the evaporator 25 and is again sucked into the compressor 21.
  • control device 4 reduces an opening degree of the main expansion valve 24, reduces a circulation amount of refrigerant which flows into the evaporator 25, and secures an absorption heat amount per unit flow rate in the evaporator 25. If the circulation amount of refrigerant is reduced, a compression ratio of refrigerant in the compressor 21 is increased and discharge temperature gradually rises. It is an object of the present invention to suppress the excessive discharge temperature rise while suppressing deterioration in operation efficiency.
  • refrigerant which flows into the evaporator 25 is supercooled, an enthalpy difference in the evaporator 25 is increased, and wet refrigerant is made to flow into the bypass passage 3.
  • a heat-transfer area of the supercooling heat exchanger 23 is set such that a heat exchange ratio Qsc/Qc which is a ratio of a heat exchange amount Qsc between refrigerant which is decompressed by the bypass passage 3 and refrigerant which flows out from the radiator 22 in the supercooling heat exchanger 23 with respect to a heat exchange amount Qc between water and refrigerant in the radiator 22 becomes 0.1 or more and 0.6 or less.
  • a local evaporation heat-transfer coefficient in the refrigerant pipe which is placed horizontally becomes a maximum value when dryness fraction is 0.8 or more and less than 1.0. If the dryness fraction of refrigerant which flows out from the evaporator 25 is adjusted in a range of 0.8 or more and less than 1.0 as in this configuration, heat-transfer efficiency of the evaporator becomes high, and operation efficiency of the refrigeration cycle apparatus 1A is enhanced.
  • the heat-transfer area of the supercooling heat exchanger 23 is appropriately set. Therefore, if the circulation amount of refrigerant which passes through the evaporator 25 is adjusted so that dryness fraction of refrigerant at the outlet of the evaporator 25 becomes an appropriate value, a circulation amount of refrigerant which flows through the bypass passage 3 is inevitably adjusted appropriately. As a result, refrigerant which flows through the refrigerant circuit 2 is appropriately supercooled, and dryness fraction of refrigerant at the outlet of the bypass passage 3 flowing out from the supercooling heat exchanger 23 becomes small.
  • a heat exchange ratio Qsc/Qc is set based on a condition that outside air temperature is low and condensation temperature is high, i.e., a condition that it is necessary to maximally secure the heat exchange amount Qsc in the supercooling heat exchanger 23 to secure heating ability in the radiator 22. That is, as shown in Figs. 4 (a) and 4 (b) , in the hot water generator, as a lower limit of outside air temperature in a heat pump apparatus, it is assumed that the outside air temperature AT is -25°C. As an upper limit of condensation temperature in a heat pump apparatus using R32, it is assumed that condensation temperature Tc is 60°C.
  • the heat exchange ratio Qsc/Qc is 0.6, the dryness fraction Xei of refrigerant which flows into the evaporator 25 becomes 0 ( ⁇ in the drawing), the enthalpy difference in the evaporator 25 is increased, and an absorption heat amount in the evaporator 25 can be secured. If the heat exchange ratio Qsc/Qc is set such that the dryness fraction Xei of refrigerant which flows into the evaporator 25 becomes greater than 0 and less than 0.43 as described above, refrigerant which flows out from the supercooling heat exchanger 23 in the refrigerant circuit 2 can reliably be supercooled.
  • heat exchange amount Qsc in the supercooling heat exchanger 23 can be secured.
  • the heat exchange ratio Qsc/Qc is set to 0.1 or more so that refrigerant on the side of the outlet of the supercooling heat exchanger 23 of the refrigerant circuit 2 can reliably be supercooled, i.e., so that the dryness fraction Xei of refrigerant which flows into the evaporator 25 reliably becomes less than 0.43.
  • the permissible temperature is set to 100° while taking deterioration of refrigerant oil in the compressor 21 and safety of compressor 21 into consideration.
  • the heat-transfer area of the supercooling heat exchanger 23 is set so that the heat exchange ratio Qsc/Qc falls within the range of 0.1 or more and 0.6 or less.
  • Pc represents pressure of refrigerant which passes through the radiator 22
  • Ps represents pressure of refrigerant which passes through the evaporator 25.
  • control operation performed by the control device 4 will be described.
  • the refrigerant circuit 2 is provided with a first temperature sensor 61 which detects temperature (evaporator temperature) Te of refrigerant which flows into the evaporator 25, a second temperature sensor 62 which detects temperature (evaporator outlet temperature) Teo of refrigerant which flows out from the evaporator 25, and a pressure sensor 51 which detects pressure (condensation pressure) Pc of refrigerant which flows into the radiator 22.
  • a first temperature sensor 61 which detects temperature (evaporator temperature) Te of refrigerant which flows into the evaporator 25
  • a second temperature sensor 62 which detects temperature (evaporator outlet temperature) Teo of refrigerant which flows out from the evaporator 25
  • a pressure sensor 51 which detects pressure (condensation pressure) Pc of refrigerant which flows into the radiator 22.
  • the control device 4 controls the number of rotations of the compressor 21, a switching operation of the four-way valve 28, and opening degrees of the main expansion valve 24 and the bypass expansion valve 31 based on detection values detected by these sensors 51, 61 and 62.
  • control device 4 controls the main expansion valve 24 so that dryness fraction of refrigerant which flows out from the evaporator 25 becomes 0.8 or more and less than 1.0 in the refrigerant circuit 2 at the time of normal operation. More specifically, an opening degree of the main expansion valve 24 is adjusted so that a temperature difference ⁇ Te between evaporation temperature Te detected by the first temperature sensor 61 and evaporator outlet temperature Teo detected by the second temperature sensor 62 becomes equal to a predetermined temperature difference ⁇ Tt.
  • the second temperature sensor 62 is placed downstream of the four-way valve 28, and temperature of refrigerant which flows out from the evaporator 25 after this refrigerant absorbs heat from discharged refrigerant of the compressor 21 in the four-way valve 28 is detected as the evaporator outlet temperature Teo. According to this, the evaporator outlet temperature Teo becomes higher than temperature of refrigerant of the outlet of the evaporator 25.
  • dryness fraction of the refrigerant of the outlet of the evaporator 25 becomes closer to a value less than 1.0 as compared with the refrigerant which absorbs heat from the discharged refrigerant of the compressor 21 in the four-way valve 28.
  • a temperature difference in which dryness fraction becomes equal to a desired value should be set to ⁇ Tt while taking a relation between temperature of refrigerant of the outlet of the evaporator 25 and the evaporator outlet temperature Teo into consideration.
  • the control device 4 sets the opening degree of the bypass expansion valve 31 to a predetermined set opening degree Sb which is determined by saturated temperature (condensation temperature) Tc calculated based on condensation pressure Pc detected by the pressure sensor 51 and evaporation temperature Te detected by the first temperature sensor 61.
  • This set opening degree Sb is set such that as the evaporation temperature Te is lower and as the condensation temperature Tc is higher, the heat exchange ratio Qsc/Qc becomes greater.
  • control device 4 controls the main expansion valve 24 and the bypass expansion valve 31 such that as the evaporation temperature Te is lower and as the condensation temperature Tc is higher, the heat exchange ratio Qsc/Qc is increased.
  • the control device 4 detects the evaporation temperature Te by the first temperature sensor 61 and the evaporator outlet temperature Teo by the second temperature sensor 62 (step S1). Then, the control device 4 calculates the temperature difference ⁇ Te by Teo - Te (step S2). Then, the control device 4 adjusts an opening degree of the main expansion valve 24 so that the temperature difference ⁇ Te becomes equal to a target temperature difference ⁇ Tt which is set such that refrigerant dryness fraction of the outlet of the evaporator 25 becomes an appropriate value (step S3).
  • control device 4 detects condensation pressure Pc by the pressure sensor 51 (step S4), and calculates saturated temperature (condensation temperature) Tc under pressure of refrigerant which flows into the radiator 22 from the detected condensation pressure Pc (step S5). This calculation of the condensation temperature Tc is carried out using a refrigerant physicality equation.
  • control device 4 determines a set opening degree Sb (step S6) corresponding to the current evaporation temperature Te and the condensation temperature Tc from a setting opening degree table in which an opening degree of the bypass expansion valve 31 determined by a predetermined evaporation temperature Te and the condensation temperature Tc is recorded, and the control device 4 adjusts the opening degree of the bypass expansion valve 31 to the set opening degree Sb (step S7).
  • control device 4 controls the bypass expansion valve 31 such that a heat exchange ratio is increased.
  • a condensation temperature detecting means 51 detects condensation temperature drop
  • the control device 4 controls the bypass expansion valve 31 such that the heat exchange ratio is increased.
  • the supercooling heat exchanger 23 is configured so that the heat exchange ratio which is a ratio of the heat exchange amount between refrigerant decompressed by the bypass expansion valve 31 and refrigerant which flows out from the radiator 22 with respect to the heat exchange amount between water and refrigerant in the radiator 22 becomes 0.1 or more and 0.6 or less, when the opening degrees of the main expansion valve 24 and the bypass expansion valve 31 in the supercooling heat exchanger 23 are adjusted such that dryness fraction of refrigerant which flows out from the evaporator 25 becomes 0.8 or more and less than 1.0.
  • the refrigerant dryness fraction at the outlet of the evaporator 25 becomes 0.8 or more and less than 1.0 at which the local evaporation heat-transfer coefficient in the horizontally placed refrigerant pipe becomes the maximum and therefore, the heat-transfer efficiency of the evaporator 25 is enhanced. Since the heat exchange ratio Qsc/Qc is set to 0.1 or more, the refrigerant supercooling degree at the outlet of the supercooling heat exchanger 23 is reliably increased, and an amount of gas phase refrigerant which flows into the evaporator 25 is reduced. Since the heat exchange ratio Qsc/Qc is set to 0.6 or less, refrigerant dryness fraction at the outlet of the bypass passage 3 is maintained at a low level.
  • control device 4 controls the main expansion valve 24 such that dryness fraction of refrigerant which flows out from the evaporator 25 at the time of normal operation becomes 0.8 or more and less than 1.0. Therefore, even if loads on the evaporation side and on the condensation side are varied, refrigerant dryness fraction at the outlet of the evaporator 25 becomes an appropriate value in accordance with the loads. Hence, reliability and energy saving of the refrigeration cycle are always enhanced.
  • bypass expansion valve 31 is controlled such that as the evaporation temperature Te in the evaporator 25 becomes lower, and as the condensation temperature Tc in the radiator 22 becomes higher, the heat exchange ratio Qsc/Qc becomes greater.
  • the pressure sensor 51 is provided between the four-way valve 28 and the radiator 22 in the refrigerant circuit 2 in Fig. 1 , the pressure sensor 51 may be provided at any position of the refrigerant circuit 2 only if the pressure sensor 51 is located between a discharging portion of the compressor 21 and an inlet of the main expansion valve 24. That is, it is only necessary that a pressure loss from the radiator 22 to the pressure sensor 51 is complemented.
  • condensation temperature detecting means may be configured by appropriately placing the pressure sensor and the temperature sensor.
  • the first temperature sensor 61 it is possible to employ such a configuration that a pressure sensor is placed between an outlet of the main expansion valve 24 and a suction portion of the compressor 21, saturated temperature is calculated based on pressure detected by the pressure sensor, and the calculated saturated temperature may be used as the evaporation temperature Te. That is, it is only necessary that the evaporation temperature detecting means is configured by appropriately placing the pressure sensor and the temperature sensor.
  • bypass passage 3 branches off from the refrigerant circuit 2 at a location between the supercooling heat exchanger 23 and the main expansion valve 24, and the bypass passage 3 may branch off from the refrigerant circuit 2 at a location between the radiator 22 and the supercooling heat exchanger 23.
  • the bypass passage 3 may be connected directly to a compression chamber of the compressor 21.
  • main expansion means and the bypass expansion means of the present invention are expansion valves, and they may be expanding machines which collect power from expanding refrigerant.
  • the number of rotations of the expanding machine may be controlled by varying a load by a generators connected to the expanding machine.
  • the to-be heated fluid which is heated by the radiator 22 is water, and the to-be heated fluid may be air. That is, the present invention can be applied also to an air conditioner.
  • the present invention is especially effective for a hot water generator which heats water by a refrigeration cycle apparatus and which utilizes the heated water for air heating.
EP14152911.5A 2013-02-08 2014-01-28 Refrigeration cycle apparatus and hot water generator provided with the same Withdrawn EP2765370A1 (en)

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CN (1) CN103983052A (ja)

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EP3249323A1 (en) * 2016-05-24 2017-11-29 Lu-Ve S.P.A. Method and system for controlling superheating of compression refrigerating cycles with a recuperator
EP3312524A4 (en) * 2015-06-18 2018-07-04 Mitsubishi Electric Corporation Refrigeration cycle device
EP3404341A1 (en) * 2017-05-15 2018-11-21 Panasonic Intellectual Property Management Co., Ltd. Refrigeration cycle apparatus and liquid circulating apparatus including the same
EP3452761A4 (en) * 2016-05-02 2020-01-08 Wong, Lee Wa CENTRAL AIR CONDITIONING AND HEAT PUMP WITH ENERGY EFFICIENT ARRANGEMENT

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CN105180536B (zh) * 2015-08-27 2018-02-06 广东美的暖通设备有限公司 一种热泵热水机除霜装置及应用该装置除霜的方法
CN107843037B (zh) * 2017-10-31 2021-02-23 广东美的暖通设备有限公司 多联机系统及其过冷控制装置和方法
WO2019234986A1 (ja) * 2018-06-07 2019-12-12 パナソニックＩｐマネジメント株式会社 冷凍サイクル装置およびそれを備えた液体加熱装置
JP7038277B2 (ja) * 2018-06-29 2022-03-18 パナソニックＩｐマネジメント株式会社 冷凍サイクル装置およびそれを備えた液体加熱装置
CN110595116A (zh) * 2019-09-24 2019-12-20 青岛澳柯玛超低温冷冻设备有限公司 单机二次节流回热式制冷循环系统
CN111121342B (zh) * 2019-12-31 2021-11-05 青岛海信日立空调系统有限公司 热泵系统
CN111578547B (zh) * 2020-05-28 2021-06-08 珠海格力电器股份有限公司 双回热制冷系统的控制方法

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JP2011080634A (ja) 2009-10-05 2011-04-21 Panasonic Corp 冷凍サイクル装置および温水暖房装置
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EP3312524A4 (en) * 2015-06-18 2018-07-04 Mitsubishi Electric Corporation Refrigeration cycle device
EP3457049A1 (en) * 2015-06-18 2019-03-20 Mitsubishi Electric Corporation Refrigeration cycle device
EP3452761A4 (en) * 2016-05-02 2020-01-08 Wong, Lee Wa CENTRAL AIR CONDITIONING AND HEAT PUMP WITH ENERGY EFFICIENT ARRANGEMENT
EP3249323A1 (en) * 2016-05-24 2017-11-29 Lu-Ve S.P.A. Method and system for controlling superheating of compression refrigerating cycles with a recuperator
EP3404341A1 (en) * 2017-05-15 2018-11-21 Panasonic Intellectual Property Management Co., Ltd. Refrigeration cycle apparatus and liquid circulating apparatus including the same
CN108870788A (zh) * 2017-05-15 2018-11-23 松下知识产权经营株式会社 制冷循环装置和具有该制冷循环装置的液体循环装置

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JP2014169854A (ja) 2014-09-18
CN103983052A (zh) 2014-08-13

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