US20040020223A1 - Supercritical refrigerant cycle system - Google Patents

Supercritical refrigerant cycle system Download PDF

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Publication number
US20040020223A1
US20040020223A1 US10/453,936 US45393603A US2004020223A1 US 20040020223 A1 US20040020223 A1 US 20040020223A1 US 45393603 A US45393603 A US 45393603A US 2004020223 A1 US2004020223 A1 US 2004020223A1
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United States
Prior art keywords
refrigerant
evaporator
degree
superheat
outlet
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.)
Abandoned
Application number
US10/453,936
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English (en)
Inventor
Shigetoshi Doi
Toshiyuki Ebara
Yoshiaki Kurosawa
Mitsuhiko Ishino
Eiji Fukuda
Yoshihiko Kobayashi
Aritomo Yoshida
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Panasonic Intellectual Property Management Co Ltd
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Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2002163293A external-priority patent/JP2004011957A/ja
Priority claimed from JP2002163296A external-priority patent/JP2004011958A/ja
Application filed by Individual filed Critical Individual
Assigned to SONY ELECTRIC CO., LTD. reassignment SONY ELECTRIC CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DOI, SHIGETOSHI, EBARA, TOSHIYUKI, FUKUDA, EIJI, ISHINO, MITSUHIKO, KOBAYASHI, YOSHIHIKO, KUROSAWA, TOSHIAKI, YOSHIDA, ARITOMO
Publication of US20040020223A1 publication Critical patent/US20040020223A1/en
Priority to US11/029,392 priority Critical patent/US7143595B2/en
Assigned to PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD. reassignment PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SANYO ELECTRIC CO., LTD.
Abandoned legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • 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
    • 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
    • F25B2600/2513—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
    • F25B2700/197—Pressures 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
    • F25B2700/2104—Temperatures of an indoor room or compartment
    • 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
    • F25B2700/2106—Temperatures of fresh outdoor air
    • 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 refrigerant cycle system in which a compressor, a gas cooler, throttle means and an evaporator are sequentially connected in a cyclic form and a high pressure side is operated at a supercritical pressure.
  • a rotary compressor compressor
  • a gas cooler for air-conditioning the inside of an automobile
  • throttle means such as an expansion valve
  • evaporator for example, a rotary compressor (compressor), a gas cooler, an intermediate heat exchanger, throttle means (such as an expansion valve), an evaporator and the like are sequentially connected in a cyclic form via pipes so as to constitute a refrigerant cycle (refrigerant circuit).
  • a refrigerant gas is sucked into a low pressure chamber of a cylinder from a suction port of a rotary compression element of the rotary compressor and then compressed by the actions of a roller and a vane so as to become a high temperature/high pressure refrigerant gas.
  • the refrigerant gas goes out of a high pressure chamber, passes through a discharge port and a discharge silencing chamber, and flows into the gas cooler so as to dissipate heat.
  • the refrigerant gas exchanges heat with a refrigerant of lower pressure in the intermediate heat exchanger, it is reduced by the throttle means and fed to the evaporator.
  • the refrigerant evaporates therein, and during the evaporation, it exhibits a cooling effect by absorbing heat from its surroundings so as to air-condition the inside of the automobile.
  • CO 2 carbon dioxide
  • Japanese Patent Publication No. 18602/1995 is used as a refrigerant in place of conventionally used from and a high pressure side is operated as a supercritical pressure even in a refrigerant cycle such as the automotive air conditioner of the above type.
  • a receiver tank is provided subsequently to the evaporator so as to reserve a liquid refrigerant therein, the degree of superheat of a refrigerant at the outlet of the evaporator is not adjusted.
  • the amount of liquid refrigerant in the receiver tank has been adjusted to control the cooling capacity (refrigerating capacity). That is, since the degree of opening of the throttle means (expansion valve) is adjusted by the amount of the liquid refrigerant reserved in the receiver tank, a refrigerant in the evaporator shifts from a state of a mixture of two phases, i.e., gas and a liquid, to a gaseous state nearly completely when, for example, the throttle means is rather closed under a high heat load. Hence, a refrigerant of lower pressure which has flown into the intermediate heat exchanger cannot cool a refrigerant of high pressure sufficiently.
  • An object of the present invention is to improve a heat exchanging capability in an evaporator in a refrigerant cycle system in which a high pressure side is operated at a supercritical pressure.
  • the degree of opening of throttle means is adjusted based on the temperature and pressure of a refrigerant at the outlet of the evaporator of the refrigerant cycle system so as to control the degree of superheat at the outlet of the evaporator.
  • the degree of superheat at the outlet of the evaporator is rendered large by, for example, the throttle means, a difference in enthalpy of the refrigerant in the evaporator becomes large, so that an optimum heat exchanging capability in the evaporator can be attained.
  • the degree of opening of the throttle means is adjusted based on heat load conditions so as to control the degree of superheat at the outlet of the evaporator.
  • the degree of superheat at the outlet of the evaporator is decreased when a heat load is high and increased when the heat load is low, a difference in enthalpy in the refrigerant in the evaporator becomes large, and an optimum cooling capacity in the evaporator can be attained.
  • the system of the present invention further comprises an intermediate heat exchanger for allowing a refrigerant coming out of a gas cooler to exchange heat with a refrigerant coming out of the evaporator and a receiver tank for temporarily reserving a refrigerant to be sucked into the compressor and causes a refrigerant coming out of the evaporator and passing through the intermediate heat exchanger to flow into the receiver tank.
  • a low temperature refrigerant coming out of the evaporator is allowed to flow into the intermediate heat exchanger without passing through the receiver tank so as to cool a refrigerant coming out of the gas cooler more effectively.
  • a further improvement in the refrigerating capacity (cooling capacity) of the evaporator can be achieved.
  • a CO 2 refrigerant is used. This can contribute to the elimination of environmental issues.
  • FIG. 1 is a longitudinal section of a multistage compression rotary compressor which constitutes a refrigerant cycle of the present invention.
  • FIG. 2 is a diagram showing a refrigerant cycle of an air conditioner for an automobile which is an embodiment of the present invention.
  • FIG. 3 is a p-h diagram of the refrigerant cycle of FIG. 2.
  • FIG. 4 is a diagram showing the relationship between the degree of superheat at the outlet of an evaporator and a cooling capacity.
  • FIG. 5 is a p-h diagram of the refrigerant cycle of FIG. 2 under a high-load for illustrating another present invention.
  • FIG. 6 is a p-h diagram of the refrigerant cycle of FIG. 2 under a low load for illustrating another present invention.
  • FIG. 7 is a diagram showing the relationship between heat load conditions for controlling the degree of superheat and the degree of superheat in another present invention.
  • FIG. 1 is a longitudinal section of an internal intermediate pressure type multistage (two stage) compression rotary compressor 10 having first and second rotary compression elements as an embodiment of a compressor used in a refrigerant cycle system of the present invention.
  • reference numeral 10 denotes an internal intermediate pressure type multistage compression rotary compressor using CO 2 (carbon dioxide) as a refrigerant.
  • the compressor 10 comprises a sealed cylindrical vessel 12 which is formed of a steel plate, an electrically driven element 14 which is placed in an upper portion of the inside of the sealed vessel 12 , and a rotary compression mechanism 18 comprising a first rotary compression element 32 (first stage) and a second rotary compression element 34 (second stage) which are placed under the electrically driven element 14 and driven by-a rotation shaft 16 of the electrically driven element 14 .
  • the sealed vessel 12 holds oil at the bottom.
  • the sealed vessel 12 comprises a vessel body 12 A which accommodates the electrically driven element 14 and the rotary compression mechanism 18 and a nearly bowl shaped end cap 12 B for closing an opening at the top of the vessel body 12 A.
  • the end cap 12 B has a circular mounting hole 12 D formed at the center of its top surface, and a terminal (wiring omitted) 20 for supplying power to the electrically driven element 14 is installed in the mounting hole 12 D.
  • the electrically driven element 14 comprises a ring-shaped stator 22 which is installed along the internal surface of the upper portion of the sealed vessel 12 and a rotor 24 which is placed inside the stator 22 with a small spacing therebetween.
  • the rotor 24 is secured to the rotation shaft 16 which passes through the center and extends in a vertical direction.
  • the stator 22 has a laminate 26 of doughnut-shaped electromagnetic steel plates and a stator coil 28 which is formed by direct winding (concentrated winding) on the tooth of the-laminate 26 . Further, the rotor 24 is formed by a laminate 30 of electromagnetic steel plates as. in the case of the stator 22 and has a permanent magnet MG inserted in the laminate 30 .
  • An intermediate partition plate 36 is held between the above first rotary compression element 32 and the above second rotary compression element 34 . That is, the first rotary compression element 32 and the second rotary compression element 34 comprise the intermediate partition plate 36 , upper and lower cylinders 38 and 40 which are placed on the upper and lower surfaces of the intermediate partition plate .
  • upper and lower rollers 46 and 48 which eccentrically rotate in upper and lower eccentric portions 42 and 44 provided on the rotation shaft 16 at a phase difference of 180° in the upper and lower cylinders 38 and 40 , vanes 50 and 52 which are in contact with the upper and lower rollers 46 and 48 so as to section the inner portions of the upper and lower cylinders 38 and 40 into low pressure chambers and high pressure chambers, and upper and lower supporting members 54 and 56 as supporting members which close the upper opened surface of the upper cylinder 38 and the lower opened surface of the lower cylinder 40 and also serve as bearings for the rotation shaft 16 .
  • the upper and lower supporting members 54 and 56 have suction passages 60 (suction passage in the upper supporting member is not shown) which communicate with the internal portions of the upper and lower cylinders 38 and 40 at suction ports which are not shown and discharge silencing chambers 62 and 64 which are formed by making dents in the supporting members and covering the dents with upper and lower covers 66 and 68 .
  • the discharge silencing chamber 64 communicates with the inside of the sealed vessel 12 via a communicating passage penetrating the upper and lower cylinders 38 and 40 and the intermediate partition plate 36 .
  • a communicating passage penetrating the upper and lower cylinders 38 and 40 and the intermediate partition plate 36 .
  • an intermediate discharge pipe 121 is disposed at the upper end of the communicating passage.
  • a refrigerant of intermediate pressure compressed by the first rotary compression element 32 is discharged from the intermediate discharge pipe 121 into the sealed vessel 12 .
  • the upper cover 66 which closes the opening at the top of the discharge silencing chamber 62 which communicates with the internal portion of the upper cylinder 38 of the second rotary compression element 34 partitions the internal portion of the sealed vessel 12 into the discharge silencing chamber 62 and the electrically driven element 14 .
  • the refrigerant As the refrigerant, the foregoing CO 2 (carbon dioxide) which is a naturally occurring refrigerant is used in consideration of ecology-friendliness, inflammability and toxicity.
  • oil as a lubricating oil an existing oil such as a mineral oil, an alkylbenzene oil, an ether oil, an ester oil or PAG (polyalkyl glycol) is used.
  • sleeves 141 , 142 , 143 and 144 are secured by welding at positions corresponding to the suction passages 60 (upper suction passage is not shown) of the upper and lower supporting members 54 and 56 , the discharge silencing chamber 62 , and a portion above the upper cover 66 (or portion corresponding to nearly the lower end of the electrically driven element 14 ).
  • a refrigerant feeding pipe 92 for feeding a refrigerant gas to the upper cylinder 38 is inserted into and connected to the sleeve 141 .
  • This end of the refrigerant feeding pipe 92 communicates with the suction passage in the upper cylinder 38 which is not shown.
  • the other end of the refrigerant feeding pipe 92 passes over the sealed vessel 12 , reaches the sleeve 144 and is inserted into and connected to the sleeve 144 so as to communicate with the internal portion of the sealed vessel 12 .
  • a refrigerant feeding pipe 94 for feeding a refrigerant gas to the lower cylinder 40 is inserted into and connected to the sleeve 142 .
  • This end of the refrigerant feeding pipe 94 communicates with the suction passage 60 in the lower cylinder 40 .
  • the other end of the refrigerant feeding pipe 94 is connected to the lower portion of a receiver tank 158 to be described later.
  • a refrigerant discharge pipe 96 is inserted into and connected to the sleeve 143 , and one end of the refrigerant feeding pipe 96 communicates with the discharge silencing chamber 62 .
  • the receiver tank 158 is a tank which subjects a refrigerant sucked into the compressor 10 to gas-liquid separation and is attached to a bracket 147 welded to the side of the upper portion of the vessel body 12 A of the sealed vessel 12 .
  • FIG. 2 shows a refrigerant cycle when the present invention is applied to an automotive air conditioner for cooling the inside of an automobile.
  • the foregoing compressor 10 constitutes a portion of the refrigerant cycle of the automotive air conditioner shown in FIG. 2. More specifically, the refrigerant discharge pipe 96 of the compressor 10 is connected to the inlet of a gas cooler 154 . A pipe extending from the gas cooler 154 reaches an electronic expansion valve 156 which serves as throttle means via an intermediate heat exchanger 160 .
  • the outlet of the expansion valve 156 is connected to the inlet of an evaporator 157 , and the outlet of the evaporator 157 reaches the above receiver tank 158 via the intermediate heat exchanger 160 .
  • the outlet of the receiver tank 158 is connected to the refrigerant feeding pipe 94 .
  • Reference numeral 171 denotes a controller for controlling (adjusting) the number of revolutions of the electrically driven element 14 of the above compressor 10 and the degree of opening of the expansion valve 156 .
  • the intermediate pressure refrigerant gas in the sealed vessel 12 goes out from the sleeve 144 , passes through the refrigerant feeding pipe 92 and the suction passage which is formed in the upper supporting member 54 and not shown, and then sucked into the low pressure chamber of the upper cylinder 38 from a suction port which is not shown.
  • the intermediate pressure refrigerant gas sucked in is subjected to second compression by the actions of the roller 46 and the vane 50 , thereby becoming a high pressure/high temperature refrigerant gas.
  • the refrigerant gas goes out of the high pressure chamber, passes through a discharge port which is not shown and is then discharged from the refrigerant discharge pipe 96 to the outside via the discharge silencing chamber 62 formed in the upper supporting member 54 .
  • the refrigerant has been compressed to a supercritical pressure (state B indicated by the solid line in FIG. 3).
  • the refrigerant gas discharged from the refrigerant discharge pipe 96 flows into the gas cooler 154 to be cooled by air or water and then passes through the intermediate heat exchanger 160 .
  • the refrigerant is then further cooled by a refrigerant of lower pressure in the exchanger 160 (state C in FIG. 3) and then reaches the expansion valve 156 .
  • the refrigerant becomes a mixture of two phases, i.e., gas and a liquid, as shown by D indicated by the solid line in FIG. 3, due to a reduction in pressure at the expansion valve 156 and flows into the evaporator 157 in that state.
  • the refrigerant evaporates therein and absorbs heat from air circulating inside the automobile.
  • the refrigerant exhibits a cooling effect so as to cool the inside of the automobile.
  • the refrigerant flows out of the evaporator 157 (state A in FIG. 3).
  • the refrigerant passes through the intermediate heat exchanger 160 so as to be heated by a refrigerant of higher pressure and then reaches the receiver tank 158 .
  • the refrigerant undergoes gas-liquid separation, and only a gas refrigerant is sucked into the first rotary compression element 32 of the compressor 10 from the refrigerant feeding pipe 94 .
  • the above cycle is repeated.
  • the controller 171 controls the number of revolutions of the electrically driven element 14 of the compressor 10 based on the outputs of the in-car temperature sensor 161 , the solar radiation sensor 162 and the outside air temperature sensor 163 so as to adjust the cooling capacity (refrigerating capacity) of the refrigerant cycle, thereby keeping the temperature of the inside of the automobile at a set temperature.
  • the controller 171 controls the degree of opening of the expansion valve 156 based on the temperature and pressure of the refrigerant at the outlet of the evaporator 157 which are detected by the temperature sensor 159 A and the pressure sensor 159 B. At that time, the controller 171 rather reduces the degree of opening of the valve so that the degree of superheat (state A indicated by the solid line in FIG. 3) at the outlet of the evaporator 157 becomes as large a value as about 5 deg.
  • the refrigerant flow rate Gr can be made smaller than Gr′ (Gr ⁇ Gr′). Further, this indicates that the external diameter of the evaporator can be reduced.
  • An invariable capacity open compressor is driven by an engine via a belt. Therefore, the number of revolutions of the compressor depends on the number of revolutions of the engine, so that the amount of circulating refrigerant changes significantly according to a change in the speed of an automobile. Hence, it is difficult to keep the degree of superheat at the outlet of an evaporator at a predetermined value at all times, and a difference from the predetermined value is absorbed by the receiver tank.
  • a variable capacity open compressor or an invariable capacity compressor driven by an electric motor undergo a small change in the amount of circulating refrigerant, so that it is easy to control the degree of superheat to a predetermined value. That is, the present invention can be more effective in a refrigerant system which undergoes a small change in the amount of circulating refrigerant.
  • the degree of opening of the throttle means is adjusted based on the temperature and pressure of a refrigerant at the outlet of the evaporator so as to control the degree of superheat at the outlet of the evaporator.
  • the system further comprises an intermediate heat exchanger for allowing a refrigerant coming out of the gas cooler to exchange heat with a refrigerant coming out of the evaporator and a receiver tank for temporarily reserving a refrigerant to be sucked into the compressor and causes a refrigerant coming out of the evaporator and passing through the intermediate heat exchanger to flow into the receiver tank.
  • an intermediate heat exchanger for allowing a refrigerant coming out of the gas cooler to exchange heat with a refrigerant coming out of the evaporator and a receiver tank for temporarily reserving a refrigerant to be sucked into the compressor and causes a refrigerant coming out of the evaporator and passing through the intermediate heat exchanger to flow into the receiver tank.
  • a CO 2 refrigerant is used in the present invention. This can contribute to the elimination of environmental issues.
  • the controller 171 controls the degree of opening of the expansion valve 156 based on the temperature and pressure of a refrigerant at the outlet of the evaporator 157 which are sensed by the temperature sensor 159 A and the pressure sensor 159 B.
  • the controller 171 estimates a heat load based on the outputs of the in-car temperature sensor 161 , the solar radiation sensor 162 and the outside air temperature sensor 163 and adjusts the degree of opening of the expansion valve 156 based on the estimated heat load and the outputs of the temperature sensor 159 A and the pressure sensor 159 B.
  • the controller 171 estimates based on the outputs of the in-car temperature sensor 161 , the solar radiation sensor 162 and the outside air temperature sensor 163 that a heat load is high, the controller 171 rather increases the degree of opening of the expansion valve 156 so as to make the degree of superheat (state E indicated by the solid line in FIG. 5) at the outlet of the evaporator 157 as small as possible.
  • the temperature of the refrigerant of lower pressure is more liable to increase when the temperature of outside air is high, so that heat exchange cannot be performed satisfactorily since a difference in temperature between the refrigerant of higher pressure and the refrigerant of lower pressure becomes small.
  • a refrigerant in the evaporator 157 does not shift from a state of a mixture of two phases, i.e., gas and a liquid, to a gaseous state completely. Then, the liquid refrigerant evaporates in the intermediate heat exchanger 160 , thereby cooling a refrigerant of higher pressure. Consequently, the temperature of a refrigerant of lower pressure hardly increases in the intermediate heat exchanger 160 and is kept low, so that the refrigerant of higher pressure can be cooled sufficiently.
  • the controller 171 estimates based on the outputs of the in-car temperature sensor 161 , the solar radiation sensor 162 and the outside air temperature sensor 163 that a heat load is low (including medium and low loads), the controller 171 rather reduces the degree of opening of the valve so that the degree of superheat (state A indicated by the solid line in FIG. 6) at the outlet of the evaporator 157 becomes as large a value as about 5 deg.
  • FIG. 7 The above control of the degree of superheat is shown in FIG. 7. That is, when the heat load estimated based on the outputs of the in-car temperature sensor 161 , the solar radiation sensor 162 and the outside air temperature sensor 163 is a low load, the controller 171 rather reduces the degree of opening of the expansion valve 156 so as to make the degree of superheat large, while when the heat load is high, the controller 171 rather increases the degree of opening of the expansion valve 156 so as to make the degree of superheat small.
  • a refrigerant coming out of the evaporator 157 and passing through the intermediate heat exchanger 160 is allowed to flow into the receiver tank 158 . Therefore, a low temperature refrigerant coming out of the evaporator 158 is allowed to flow into the intermediate heat exchanger without passing through the receiver tank 158 so as-to cool a refrigerant coming out of the gas cooler more effectively. Thereby, a further improvement in the cooling capacity can be made.
  • a heat load is estimated based on a combination of the outputs of the in-car temperature sensor 161 , the solar radiation sensor 162 and the outside air temperature sensor 163 .
  • the present invention is not limited to such an embodiment, and the present invention is also effective in an embodiment in which a heat load is estimated based on the output of each of the ih-car temperature sensor, the solar radiation sensor or the outside air temperature sensor.
  • the degree of opening of the throttle means is adjusted based on heat load conditions so as to control the degree of superheat at the outlet of the evaporator.
  • the refrigerating capacity of the evaporator can be retained in an optimum condition all the time even if heat load conditions are changed.
  • the system comprises a receiver tank for temporarily reserving a refrigerant to be sucked into the compressor and causes a refrigerant coming out of the evaporator and passing through the intermediate heat exchanger to flow into the receiver tank.
  • a low temperature refrigerant coming out of the evaporator is allowed to flow into the intermediate heat exchanger without passing through the receiver tank so as to cool a refrigerant coming out of the gas cooler more effectively.
  • a further improvement in the cooling capacity of the evaporator can be achieved.
  • a CO 2 refrigerant is used. This can contribute to the elimination of environmental issues.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Air-Conditioning For Vehicles (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
US10/453,936 2002-06-04 2003-06-04 Supercritical refrigerant cycle system Abandoned US20040020223A1 (en)

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US11/029,392 US7143595B2 (en) 2002-06-04 2005-01-06 Supercritical refrigerant cycle system

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JP2002163293A JP2004011957A (ja) 2002-06-04 2002-06-04 超臨界冷媒サイクル装置
JP2002-163296 2002-06-04
JP2002163296A JP2004011958A (ja) 2002-06-04 2002-06-04 超臨界冷媒サイクル装置
JP2002-163293 2002-06-04

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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US20070074538A1 (en) * 2005-09-07 2007-04-05 Denso Corporation Refrigeration cycle device
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KR20030095240A (ko) 2003-12-18
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US7143595B2 (en) 2006-12-05
EP1369648A2 (en) 2003-12-10
US20050150240A1 (en) 2005-07-14

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