US20100205987A1 - Refrigeration cycle apparatus - Google Patents

Refrigeration cycle apparatus Download PDF

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Publication number
US20100205987A1
US20100205987A1 US12/738,924 US73892408A US2010205987A1 US 20100205987 A1 US20100205987 A1 US 20100205987A1 US 73892408 A US73892408 A US 73892408A US 2010205987 A1 US2010205987 A1 US 2010205987A1
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Prior art keywords
temperature
detection means
refrigerant
outlet
heat exchanger
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US12/738,924
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English (en)
Inventor
Takashi Okazaki
Fumitake Unezaki
Tomoyoshi Oobayashi
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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: OKAZAKI, TAKASHI, OOBAYASHI, TOMOYOSHI, UNEZAKI, FUMITAKE
Publication of US20100205987A1 publication Critical patent/US20100205987A1/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
    • 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
    • F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
    • 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
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
    • F25B2309/061—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical pressure
    • 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
    • F25B2341/00—Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
    • F25B2341/06—Details of flow restrictors or expansion valves
    • F25B2341/063—Feed forward 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
    • F25B2600/17—Control issues by controlling the pressure 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
    • 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
    • F25B2700/19—Pressures
    • F25B2700/193—Pressures of the compressor
    • F25B2700/1933—Suction pressures
    • 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
    • F25B2700/2102—Temperatures at the outlet of the gas cooler
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2115—Temperatures of a compressor or the drive means therefor
    • F25B2700/21151—Temperatures of a compressor or the drive means therefor at the suction side of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2115—Temperatures of a compressor or the drive means therefor
    • F25B2700/21152—Temperatures of a compressor or the drive means therefor at the discharge side of the compressor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a condenser
    • F25B2700/21161—Temperatures of a condenser of the fluid heated by 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
    • F25B40/00—Subcoolers, desuperheaters or superheaters

Definitions

  • the present invention relates to a refrigeration cycle apparatus using an internal heat exchanger, more particularly to a refrigerant control for stably securing performance.
  • a hot water supply apparatus is proposed as a built-in refrigeration cycle apparatus such as:
  • a hot water supply apparatus comprising a refrigeration cycle including a compressor, a hot water supply heat exchanger, an electronic expansion valve, and a heat source side heat exchanger whose heat source is an external air, and a hot water supply cycle including a hot water supply heat exchanger and a hot water supply tank,
  • expansion valve opening degree control means for controlling an opening degree of an electronic expansion valve so as to make a discharge temperature of a compressor to be a target value in response to changes in external environment conditions (an external temperature, for example) of the heat source side heat exchanger and rotation speed control means for controlling a rotation speed of the compressor to be a target value in response to changes in the external environment conditions of the heat source side heat exchanger are attached
  • an opening of the electronic expansion valve is controlled so as to make the discharge temperature of the compressor becomes a target value in response to changes in the external environment conditions (an external temperature, for example) of the heat source side heat exchanger
  • the rotation speed of the compressor is controlled to be a target value in response to changes in the external environment conditions of the heat source side heat exchanger
  • a water heater is also proposed such as:
  • a water heater for heating a hot water supply fluid in a supercritical heat pump cycle where a refrigerant pressure in a high pressure side becomes equal to or more than the critical pressure of the refrigerant comprising:
  • a radiator that performs heat exchange between a refrigerant discharged from the compressor and a hot water supply fluid and is configured so that a refrigerant flow and the hot water supply fluid flow opposes
  • an evaporator that makes the refrigerant that flows out of the compressor evaporate, makes the refrigerant absorb a heat to discharge it into a suction side of the compressor
  • a refrigerant pressure of a high-pressure side is controlled so that a temperature difference ( ⁇ T) between the refrigerant that flows out of the radiator and the hot water supply fluid that flows therein becomes a predetermined temperature difference ( ⁇ To).
  • ⁇ T temperature difference
  • ⁇ To predetermined temperature difference
  • Patent Document 1 Japanese Patent Gazette No. 3601369 (pp. 6; FIG. 1)
  • Patent Document 2 Japanese Patent Gazette No. 3227651 (pp. 1-3; FIG. 2)
  • the present invention is made to solve the above problems in the prior art.
  • the object is to obtain a refrigeration cycle apparatus capable of stably achieving efficient operation conditions by controlling operation values based on standard conditions of the radiator and outlet conditions of the radiator to be a target value.
  • the refrigeration cycle apparatus includes at least a compressor, a radiator, decompression means capable of changing an open degree, a heat absorber, an internal heat exchanger that performs heat exchange between a refrigerant at an outlet of the radiator and the refrigerant at the outlet of the heat absorber.
  • the refrigeration cycle apparatus is characterized in that at least first refrigerant conditions detection means for detecting standard conditions of the radiator and second refrigerant conditions detection means for detecting refrigerant conditions between an outlet of the radiator and a high-pressure side inlet of an internal heat exchanger are provided, and an opening degree of decompression means is controlled so that a calculation value calculated based on an output of the first refrigerant conditions detection means and the output of the second refrigerant conditions detection means becomes a target value.
  • the expansion valve opening degree is controlled so that the COP becomes maximum based on standard conditions of the radiator and refrigerant conditions of the radiator outlet part, so that a refrigerant cycle apparatus capable of stably achieving efficient operation can be obtained.
  • FIG. 1 is a diagram showing a configuration of a refrigeration cycle apparatus according to Embodiment 1 of the present invention.
  • FIG. 2 is a diagram showing an operation behavior on a P-h diagram according to Embodiment 1 of the present invention.
  • FIG. 3 is a diagram showing a temperature distribution of a refrigerant and water in a water heat exchanger according to Embodiment 1 of the present invention.
  • FIG. 4 is a diagram showing cycle conditions against an expansion valve opening degree according to Embodiment 1 of the present invention.
  • FIG. 5 is a diagram showing changes in each calculation value, heating ability, and COP against an expansion valve opening degree according to Embodiment 1 of the present invention.
  • FIG. 6 is a diagram showing changes in other calculation value, heating ability, and COP against an expansion valve opening degree according to Embodiment 1 of the present invention.
  • FIG. 7 is a diagram showing a control flowchart according to Embodiment 1 of the present invention.
  • FIG. 8 is a diagram showing a refrigeration cycle apparatus according to Embodiment 2 of the present invention.
  • FIG. 9 is a diagram showing an operation behavior on a P-h diagram according to Embodiment 2 of the present invention.
  • Embodiment 1 Descriptions will be given to a refrigerant cycle apparatus by Embodiment 1 according to the present invention.
  • FIG. 1 shows a configuration diagram of the refrigerant cycle apparatus according to the present embodiment.
  • the refrigerant cycle apparatus according to the present embodiment is a hot water supply apparatus using carbon dioxide (hereinafter, CO 2 ) as a refrigerant, composed of a heat source apparatus 50 , a hot water storage apparatus 60 , and a controller 40 for controlling these.
  • CO 2 carbon dioxide
  • the present embodiment shows an example of the hot water supply apparatus, however, it is not limited thereto.
  • the apparatus may be an air conditioner.
  • the refrigerant is not limited to carbon dioxide but an HFC refrigerant may be used.
  • the heat source apparatus 50 is composed of a compressor 1 for compressing the refrigerant, a radiator 2 (hereinafter, referred to “water heat exchanger”) for taking out heat of a high-temperature high-pressure refrigerant compressed in the compressor 1 , an internal heat exchanger 5 for further cooling the refrigerant output from the water heat exchanger 2 , a decompressor 3 (hereinafter, referred to “expansion valve”) that decompresses the refrigerant and whose opening degree can be changed, an heat-absorber 4 (hereinafter, referred to “evaporator”) for evaporating the refrigerant decompressed in the expansion valve 3 , and an internal heat exchanger 5 for further heating the refrigerant flowed out of the evaporator 4 .
  • a compressor 1 for compressing the refrigerant
  • a radiator 2 hereinafter, referred to “water heat exchanger”
  • water heat exchanger 5 for further cooling the refrigerant output from the water heat exchanger 2
  • the internal heat exchanger 5 is a heat exchanger that heat-exchanges the refrigerant at an outlet of the water heat exchanger 2 with the refrigerant at the outlet of the evaporator 4 .
  • a blower 29 is provided for sending air on an outer surface of the evaporator 4 .
  • first temperature detection means 30 for detecting a discharge temperature of the compressor 1
  • second temperature detection means 31 for detecting an outlet temperature of the water heat exchanger 2
  • fifth temperature detection means 32 for detecting an inlet refrigerant temperature of the evaporator 4
  • sixth temperature detection means 33 for detecting a suction temperature of the compressor 1 .
  • the first temperature detection means 30 and the second temperature detection means 31 correspond to a first refrigerant conditions detection means and second refrigerant conditions detection means respectively in an example of control in FIG. 7 to be described later.
  • a hot water storage apparatus 60 is connected with the water heat exchanger 2 , which is a radiator, via piping, being composed of a heat source side pump 20 , a hot water storage tank 21 , a use side pump 22 , and on-off valves 23 , 24 , 25 .
  • on-off valves 23 , 24 , 25 may be a simple valve only for switching operation or an opening variable valve.
  • the on-off valves 24 , 25 are closed, the on-off valve 23 is opened, and hot water storage operation is performed in which supplied water is heated up to a predetermined temperature.
  • the on-off valves 23 , 25 are closed, the on-off valve 24 is opened, and circulation heating operation is performed in which low-temperature hot water in the hot water storage tank 21 is re-boiled.
  • the on-off valves 23 , 24 are closed, the on-off valve 25 is opened, the use side pump 22 starts operation to transfer stored hot water to the use side.
  • third temperature detection means 41 is attached for detecting an inlet temperature of a medium (water) to be heated.
  • fourth temperature detection means 42 is attached for detecting the outlet temperature of the medium (water) to be heated.
  • a controller 40 performs calculation using detected values from first temperature detection means 30 , second temperature detection means 31 , fifth temperature detection means 32 , sixth temperature detection means 33 , third temperature detection means 41 , and fourth temperature detection means 42 to control an opening degree of the expansion valve 3 , a rotation speed of the compressor 1 , and the rotation speed of the hot water supply side pump 20 , respectively.
  • FIG. 2 is a P-h diagram describing cycle conditions during hot water storage operation in the refrigeration cycle apparatus shown in FIG. 1 .
  • solid lines denote refrigerant conditions at a certain expansion valve opening degree and A, B, C, D, and E denote refrigerant conditions in the hot water storage operation.
  • A high-temperature high-pressure refrigerant
  • A discharged from the compressor 1 flows into the water heat exchanger 2 .
  • the refrigerant heats supplied water while dissipating heat to water circulating the hot water storage circuit to decrease the own temperature.
  • a refrigerant (B) flowed out of the water heat exchanger 2 dissipates heat in the internal heat exchanger 5 to further decrease (C) the temperature, being decompressed (D) by the expansion valve 3 to turn into a low-temperature low-pressure refrigerant.
  • the low-temperature low-pressure refrigerant absorbs heat from the air in the evaporator 4 to evaporate (E).
  • the refrigerant flowed out of the evaporator 4 is heated in the internal heat exchanger 5 to turn into a gas (F) and sucked by the compressor 1 to form a refrigeration cycle.
  • the expansion valve 3 is controlled so that a suction superheat degree of the compressor 1 becomes a target value (for example, 5 to 10° C.).
  • a target value for example, 5 to 10° C.
  • a detection value of fifth temperature detection means 32 detecting an inlet refrigerant temperature of the evaporator 4 a temperature decrease amount due to a pressure loss in the evaporator 4 and the internal heat exchanger 5 is corrected, an evaporation temperature (ET) is estimated, a suction superheat degree SH s is calculated by the following formula using a detection value (T s ) of sixth temperature detection means 33 detecting a suction temperature of the compressor 1 .
  • an opening degree of the expansion valve 3 is controlled so that SH s becomes a target value.
  • An example is given in which an evaporation temperature (ET) is estimated based on the detection value of the fifth temperature detection means 32 , however, it is not limited thereto.
  • Pressure detection means (second pressure detection means) 51 (refer to FIG. 1 ) is installed between a low-pressure side outlet of the internal heat exchanger 5 and the inlet of the compressor 1 , and from the detection value, a refrigerant saturation temperature may be obtained.
  • a suction superheat degree control precedes other high efficiency operation control because a function to prevent liquid return of the compressor 1 precedes a function to efficiently operate the water heat exchanger 2 from the viewpoint of securing reliability of the equipment.
  • FIG. 3 shows a refrigerant and water temperature distribution in the water heat exchanger 2 .
  • thick solid lines show a change in refrigerant temperature
  • a thin solid lines denote a change in water temperature.
  • ⁇ T 1 denotes a temperature difference between the water heat exchanger inlet temperature and water outlet temperature
  • ⁇ T 2 denotes a temperature difference between the water heat exchanger outlet temperature and water inlet temperature.
  • ⁇ Tp is a temperature difference at a pinch point where the temperature difference between a refrigerant and water in the water heat exchanger 2 becomes minimum.
  • ⁇ T denotes a temperature difference between the water heat exchanger inlet temperature and the water heat exchanger outlet temperature.
  • FIG. 5 shows changes in operation values obtained from the temperature of each part when the opening degree of the expansion valve 3 changes.
  • the horizontal axis represents the opening degree (%) of the expansion valve 3
  • the vertical axis represents the suction superheat degree, discharge temperature, temperature difference ⁇ T 2 between the outlet temperature of the water heat exchanger and water inlet temperature, heating ability ratio, COP ratio.
  • the heating ability ratio and COP ratio show a ratio when a maximum value against the expansion valve opening degree is set as 100%, respectively.
  • changes in the suction superheat degree can be regarded as almost a constant value, so that it is understood that changes in the heating ability ratio and the COP ratio cannot be judged by the suction superheat degree.
  • changes in the discharge temperature and temperature difference ⁇ T 2 are small in the vicinity of the expansion valve opening degree when the COP reaches maximum as shown by a dotted line in the figure, so that it is found that a high accuracy temperature measurement is required for controlling COP to be maximum.
  • FIG. 6 shows changes in other operation values obtained from temperatures of each part when the opening degree of the expansion valve 3 is changed.
  • the horizontal axis represents the opening degree (%) of the expansion valve 3 .
  • the vertical axis represents an outlet/inlet temperature difference ⁇ Thx of the internal heat exchanger, a temperature difference ⁇ T between a discharge temperature and an outlet temperature of the water heat exchanger, a total temperature difference ⁇ T of the above ⁇ T 1 and ⁇ T 2 , heating ability, and a COP ratio, respectively.
  • a total temperature difference ⁇ T of the temperature difference ⁇ T 1 between the water heat exchanger inlet temperature and water outlet temperature and the temperature difference ⁇ T 2 between the water heat exchanger outlet temperature and water inlet temperature becomes a minimum.
  • the control based on such an index has a physical meaning and being reasonable.
  • high-precision temperature detection is required because change in temperature is small in the vicinity where the COP becomes a maximum compared with the temperature difference ⁇ T.
  • FIG. 3 it is considered that when the COP becomes a maximum value, a temperature difference ⁇ Tp at a pinch point is almost the same as that of ⁇ T 2 between the water heat exchanger outlet temperature and water inlet temperature.
  • FIG. 7 is a flowchart showing a control operation of the refrigeration cycle apparatus.
  • the suction superheat degree (SHs) control of the compressor 1 precedes the temperature difference ⁇ T control for securing the heating ability.
  • the expansion valve opening degree is increased until the suction superheat degree (SHs) converges.
  • the temperature difference ⁇ T is made to converge at the target value.
  • the temperature difference ⁇ T is made to converge at the target value.
  • the expansion opening degree is increased and ⁇ T is made to converge.
  • ⁇ Thx When using ⁇ Thx, internal heat exchanger outlet temperature detection means 52 is attached (refer to FIG. 1 ) between a high-pressure side outlet of the internal heat exchanger 5 and an inlet of the expansion valve 3 , the temperature difference ⁇ Thx is obtained from a detection temperatures by the second temperature detection means 31 and the internal heat exchanger outlet temperature detection means 52 .
  • the expansion valve opening degree is made to be controlled so that the COP becomes maximum based on a temperature difference ⁇ T (or ⁇ T, ⁇ T 1 ⁇ T 2 , ⁇ Thx) between the discharge temperature and the water heat exchanger outlet temperature, a high efficiency refrigeration cycle apparatus can be obtained.
  • a refrigerant saturation temperature (ET) is obtained based on an output of the fifth temperature detection means 32 or pressure detection means, the suction superheat degree (SHs) is obtained by the detection temperature (Ts) of the sixth temperature detection means and the refrigerant saturation temperature (ET), and the expansion valve opening degree is controlled so that the suction superheat degree (SHs) becomes a target value, so that the superheat degree of the suction part of the compressor 1 is secured, liquid return to the compressor 1 can be prevented, and reliability can be secured.
  • Ts detection temperature
  • ET refrigerant saturation temperature
  • the fifth temperature detection means 32 is provided between the expansion valve 3 and the evaporator 4 , it can be disposed at any position between the inlet of the evaporator 4 and a low-pressure side inlet of the internal heat exchanger 5 .
  • the control of the superheat degree precedes the control of the above temperature differences. From this point, the reliability of the compressor 1 is secured.
  • the radiator is composed of the water heat exchanger, so that a high efficiency hot water supply apparatus can be obtained.
  • FIG. 8 is a drawing showing a configuration of the refrigeration cycle apparatus according to the present invention.
  • a first pressure detection means 35 is provided in place of the first temperature detection means 30 for detecting the discharge temperature of the compressor 1 .
  • a virtual saturation temperature is obtained, which is a standard condition of the water heat exchanger 2 .
  • the pressure detection means 35 can be shared with a pressure sensor provided, for example, to prevent an abnormal rise in high pressure. Descriptions on an operation behavior will be omitted because they are the same as Embodiment 1.
  • a virtual superheat degree of the water heat exchanger 2 outlet is calculated to control the refrigerant conditions thereof.
  • a virtual saturation temperature is calculated as a standard condition of the water heat exchanger 2 and from the difference between a virtual saturation temperature Tsat and outlet temperature Tcount of the water heat exchanger 2 detected by the second temperature detection means 31 , a virtual superheat degree SC is obtained from the following formula.
  • the opening degree of the expansion valve 3 is controlled in the same way as the flowchart of FIG. 7 so that the SC obtained by the above formula becomes a target value (SCm) whose efficiency is maximum.
  • FIG. 9 is a diagram showing an operation behavior of the refrigeration cycle apparatus according to the present invention on a P-h diagram.
  • the virtual saturation temperature can be freely defined by demonstrating a definition such as a pseudo critical temperature trajectory connecting flexion points of isothermal lines like a dashed line ⁇ and a vertical line like a dotted line ⁇ extended with an enthalpy at a critical point being a constant.
  • a virtual saturation temperature should be selected under which the temperature difference becomes large in the vicinity of the maximum efficiency as mentioned above.
  • the virtual saturation temperature can be obtained as an intersection of a constant pressure line with a pressure at a point B, which is a detection value by first pressure detection means 35 and the dashed line ⁇ , or as an intersection of a constant pressure line with a pressure at a point B, which is a detection value by first pressure detection means 35 and the dotted line ⁇ .
  • first temperature detection means 30 in FIG. 1 can be omitted and low cost can be achieved.
  • superheat degree of the outlet of the water heat exchanger 2 is controlled, therefore, control of the expansion valve can be applied as it is, which has been conventionally used.
US12/738,924 2007-11-30 2008-11-20 Refrigeration cycle apparatus Abandoned US20100205987A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2007310097A JP4948374B2 (ja) 2007-11-30 2007-11-30 冷凍サイクル装置
JP2007-310097 2007-11-30
PCT/JP2008/071069 WO2009069524A1 (ja) 2007-11-30 2008-11-20 冷凍サイクル装置

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US12/738,924 Abandoned US20100205987A1 (en) 2007-11-30 2008-11-20 Refrigeration cycle apparatus

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Country Link
US (1) US20100205987A1 (de)
EP (5) EP2647927B1 (de)
JP (1) JP4948374B2 (de)
CN (2) CN101842645B (de)
DK (5) DK2196745T3 (de)
ES (5) ES2700938T3 (de)
WO (1) WO2009069524A1 (de)

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US20130219936A1 (en) * 2010-10-15 2013-08-29 Toshiba Carrier Corporation Heat source apparatus
US20140083124A1 (en) * 2011-08-04 2014-03-27 Mitsubishi Electric Corporation Refrigeration apparatus
US20150253045A1 (en) * 2012-10-08 2015-09-10 Denso Corporation Refrigeration cycle device
US20150330689A1 (en) * 2012-12-26 2015-11-19 Mitsubishi Electric Corporation Refrigeration cycle apparatus and control method of refrigeration cycle apparatus
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US11365921B2 (en) * 2015-09-18 2022-06-21 Carrier Corporation System and method of freeze protection for a chiller
US20210231355A1 (en) * 2018-10-10 2021-07-29 Mitsubishi Electric Corporation Plate heat exchanger and heat pump apparatus
DE102020115274A1 (de) 2020-06-09 2021-12-09 Stiebel Eltron Gmbh & Co. Kg Verfahren zum Betrieb einer Kompressionskälteanlage
DE102021127213A1 (de) 2021-10-20 2023-04-20 Lauda Dr. R. Wobser Gmbh & Co. Kg Kälteanlage und Verfahren zum Betreiben einer Kälteanlage
EP4311990A1 (de) * 2022-07-26 2024-01-31 Lauda Dr. R. Wobser GmbH & Co. KG Prozesskühlaggregat und verfahren zur regelung eines prozesskühlaggregats
DE102022118670A1 (de) 2022-07-26 2024-02-01 Lauda Dr. R. Wobser Gmbh & Co. Kg Prozesskühlaggregat und Verfahren zur Regelung eines Prozesskühlaggregrats

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EP2647926A2 (de) 2013-10-09
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EP2647925A2 (de) 2013-10-09
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EP2647926B1 (de) 2018-10-24
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DK2647927T3 (da) 2020-10-19
DK2647925T3 (en) 2017-02-06
ES2605462T3 (es) 2017-03-14
CN102425872B (zh) 2014-06-25
WO2009069524A1 (ja) 2009-06-04
EP2196745A1 (de) 2010-06-16
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EP2647927A3 (de) 2015-07-29
DK2647928T3 (en) 2016-12-12

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