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
  • F25B40/00—Subcoolers, desuperheaters or superheaters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/10—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically
  • F28D7/106—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically consisting of two coaxial conduits or modules of two coaxial conduits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
  • F28F1/42—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being both outside and inside the tubular element
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
  • F28F1/42—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being both outside and inside the tubular element
  • F28F1/422—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being both outside and inside the tubular element with outside means integral with the tubular element and inside means integral with the tubular element
• • 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

Definitions

• the present invention relates to a refrigeration cycle to be employed, for example, in an automobile air-conditioning refrigeration cycle, and also relates to an intermediate heat exchanger and a heat exchanger for use in such a cycle.
• Freon series refrigerant has been used. In recent years, however, it is getting to draw the attention of a refrigeration cycle using natural refrigerant such as carbon dioxide (CO 2 ) .
• refrigerant circulates such that high pressure refrigerant from a compressor and a gas cooler (condenser) passes through a decompressor and an evaporator into low pressure refrigerant and returns to the compressor.
• a gas cooler condenser
• tubular structure intermediate heat exchangers disclosed in, for example, the following patent documents have been known.
• Patent Document 1 Japanese Unexamined Laid-open Patent Document No. 2001-56188
• Patent Document 2 Japanese Unexamined Laid-open Patent Document No. 2002-181466
• Patent Document 3 In a heat exchanger as disclosed in International Publication No. WO 03/085344 (hereinafter, "Patent Document 3"), it is constituted by a tubular element in which an inner tube provided with a plurality of fins on an external periphery of the inner tube is inserted in an outer tube. In this heat exchanger, high pressure refrigerant passes through the inner tube and low pressure refrigerant passes in between both tubes to exchange the heat therebetween.
• the preferred embodiments of the present invention have been developed in view of the above-mentioned and/or other problems in the related art.
• the preferred embodiments of the present invention can significantly improve upon existing methods and/or apparatuses.
• some embodiments can provide a heat exchanger capable of improving heat exchanging performance and excellent in bending workability.
• some embodiments can provide an intermediate heat exchanger capable of improving heat exchanging performance and excellent in bending workability.
• some embodiments can provide a refrigeration cycle using the aforementioned heat exchanger or intermediate heat exchanger.
• the heat exchanger according to the present invention has the following structure as recited in the following Items [1] to [20].
• a heat exchanger comprising: an outer tube; an inner tube having a plurality of fins formed on an external periphery of the inner tube, the inner tube being disposed, in the outer tube; first fluid passing in the inner tube; and second fluid passing in between the outer tube and the inner tube, wherein the heat exchanger exchanges heat between the first fluid and the second fluid, and wherein a gap is formed between an internal periphery of the outer tube and a tip end of each of the plurality of fins of the inner tube.
• An intermediate heat exchanger for exchanging heat between high pressure refrigerant and low pressure refrigerant among refrigerant circulating a refrigeration cycle.
• the intermediate heat exchanger comprising: an inner tube provided with a plurality of fins on an external periphery thereof; and an outer tube in which the inner tube is disposed in a manner such that a gap is formed between an internal periphery of the outer tube and a tip end of each of the plurality of fins of the inner tube, wherein one of the high pressure refrigerant and the low pressure refrigerant passes through a first heat exchanging passage formed in the inner tube, and wherein the other of the high pressure refrigerant and the low pressure refrigerant passes through a second heat exchanging passage between the outer tube and the inner tube.
• An intermediate heat exchanger for exchanging heat between high pressure refrigerant and low pressure refrigerant among refrigerant circulating a refrigeration cycle.
• the intermediate heat exchanger comprising: an inner tube provided with a plurality of fins on an external periphery thereof; and an outer tube in which the inner tube is disposed in a manner such that a gap is formed between an internal periphery of the outer tube and the plurality of fins of the inner tube, wherein one of the high pressure refrigerant and the low pressure refrigerant passes through a first heat exchanging passage formed in the inner tube, and wherein the other of the high pressure refrigerant and the low pressure refrigerant passes through a second heat exchanging passage between the outer tube and the inner tube.
• the heat exchanger can be formed by combining the inner tube having fins and the outer tube. Therefore, as compared with the case in which a heat exchanging multi-bored tube is formed by a single extrusion procedure, the fin and tube can be decreased in thickness, and minute structure thereof can be formed. Accordingly, the heat exchanging performance can be improved.
• the heat exchanger can be bent easily and accurately into a desired configuration.
• the heat exchanger is excellent in bending performance.
• the second fluid can be mixed via the gaps, which can prevent deflection of the refrigerant temperature distribution.
• the heat exchanging efficiency can be further improved. According to the heat exchanger as recited in the aforementioned Item [2], the heat exchanging efficiency can be improved.
• the heat exchanging efficiency can be further improved.
• Fig. 1 is a refrigeration circuit diagram of an automobile air-conditioning refrigeration system in which an intermediate heat exchanger according to an embodiment of this invention is employed;
• Fig. 2 is a cross-sectional view showing the intermediate heat exchanger of the embodiment.
• Fig. 1 shows a refrigerant circuit diagram showing an automobile air-conditioning refrigeration system in which a heat exchanger according to an embodiment of this invention is employed.
• this refrigeration cycle uses carbon dioxide as refrigerant and includes a compressor 1, a gas cooler (condenser 2), a decompressor such as an expansion valve 3, an evaporator 4, and an intermediate heat exchanger 10 which will be detailed.
• a refrigerant circulation circuit is formed. That is, the refrigerant compressed by the compressor 1 is cooled by the gas cooler 2, and then decompressed by the expansion valve 3. Thereafter, the refrigerant is evaporated by the evaporator 4 and then returns to the compressor 1.
• the high pressure refrigerant (forwarding refrigerant) flowing from the gas cooler 2 toward the expansion valve 3 passes through a high pressure refrigerant heat exchanging passage 25 in the intermediate heat exchanger 10, and the low pressure refrigerant (returning refrigerant) flowing from the evaporator 4 toward the compressor 1 passes through a low pressure refrigerant heat exchanger passage 35 to exchange the heat therebetween.
• the intermediate heat exchanger 10 has a double-tube structure including an inner tube 20 which is an aluminum (including its alloy) extruded member and an outer tube 30 which is an aluminum (including its alloy) extruded member.
• the inner tube 20 is provided a plurality of fins 21 integrally formed on the external periphery of the inner tube.
• the fins 21 extend along the longitudinal direction of the tube and arranged on the external periphery at certain equal intervals in the circumferential direction.
• a plurality of inner fins 22 extending along the longitudinal direction of the inner tube and arranged at certain equal intervals in the circumferential direction are integrally provided.
• the outer tube 30 has a tube aperture having an internal diameter larger than the external diameter of the fins 21 of the inner tube 20, and the inner tube 20 is inserted in the tube aperture of the outer tube in a manner such that the axial center of the inner tube 20 coincides with that of the outer tube 30.
• the inside of the inner tube 20 constitutes a first heat exchanging passage 25 through which high pressure refrigerant (first fluid) passes, and the space between the inner tube 20 and the outer tube 30 constitutes a second heat exchanging passage 35 through which low pressure refrigerant (second fluid) passes.
• the inner tube 20 is disposed in the outer tube 30 so as to form a gap S between the tip end of the fin 21 and the internal periphery of the outer tube 30 so that the inner tube 20 is not restrained by the outer tube 30.
• the size Ls of the gap S is adjusted to 0.2 to 1 mm.
• the difference between the inner diameter of the outer tube 30 and the external diameter of the inner tube 20 including the fins 21 is adjusted to 0.4 to 2 mm.
• the gap S is smaller than the lower limit, the inner tube 20 may be restrained by the outer tube 30, and therefore external force applied to the outer tube 30 greatly acts on the inner tube 20. Therefore, when the intermediate heat exchanger 10 constituted by both the tubes 20 and 30 is subjected to bending work, the bending stress will concentrate on the outside of the bending portion of the fins 21 of the inner tube 20, which may cause cracks in fins 21.
• the gap S is larger than the upper limit, the size (height) of the fin 21 becomes small (low), which may cause deteriorated heat transfer property, resulting in deteriorated heat exchanging performance.
• the number of fins 21 is set to 13 to 18, more preferably 15 to 17. If the number of fins is smaller than the lower limit, the heat transfer property may deteriorate, which in turn may cause a deterioration of heat exchanging performance. On the other hand, if the number of fins exceeds the upper limit, the fin pitch becomes small, decreasing the width between adjacent fins, which results in deteriorated heat exchanging performance due to the increased flow resistance of the refrigerant passing threrethrough.
• the thickness T of the fin 21 is set to 0.3 to 1.3 mm, more preferably
• the fin thickness T is smaller than the lower limit, it becomes difficult to secure sufficient strength. To the contrary, if the fin thickness T exceeds the upper limit, the heat transfer property deteriorates and the flow resistance increases, resulting in deteriorated heat exchanging performance.
• the opening angle ⁇ of the adjacent fins 21 and 21 is preferably set to 15 to 30 ° , more preferably 18 to 26° . If the opening angle ⁇ is smaller than the lower limit, the width between the adjacent fins 21 and 21 becomes small, causing increased flow resistance of the refrigerant passing therethrough, which in turn results in deteriorated heat exchanging performance. To the contrary, if the opening angle ⁇ exceeds the upper limit, the number of fins 21 decreases, causing deteriorated heat transfer performance, which in turn results in deteriorated heat exchanging performance.
• the inner tube 20 with fins is inserted and disposed in the outer tube 30 as mentioned above. Therefore, the heat exchanger can be manufactured by forming both the tubes 20 and 30 separately and then combining them.
• the fin and tube can be decreased in thickness, and minute structure thereof can be formed. Accordingly, desired heat transfer performance and heat exchanging performance can be attained more assuredly. Furthermore, in this embodiment, since a gap S is formed between the tip end of the fin 21 of the inner tube 20 and the internal periphery of the outer tube 30, the inner tube 20 will not be restrained excessively by the outer tube 30.
• the heat exchanger can be bent easily and accurately into a desired configuration because of the excellent bending performance.
• the heat exchanger can be bent into a desired configuration in accordance with the limited available installing space in the automobile, which dramatically improves the degree of design freedom.
• the gap S is formed at the tip end of each fin 21 in the second heat exchanging passage 35, the refrigerant in the heat exchanging passage 35 will be mixed via the gaps S. Therefore, deflection of the refrigerant temperature distribution can be effectively prevented, which further improves the heat exchanging efficiency.
• the conditions were set as follows: the length of the intermediate heat exchanger (length of the outer tube) was set to 500 mm, the external diameter of the outer tube 30 was set to 21.0 mm, the internal diameter of the outer tube 30 was set to 15.0 mm, the external diameter of the inner tube 20 including the outer fins 21 was set to 14.0 mm, the external diameter of the inner tube 20 excluding the outer fins 21 was set to 7.0 mm, the internal diameter of the tubular portion of the inner tube 20 excluding the inner fins 22 was set to 4.0 mm, and the inner diameter of the inner tube 20 including the inner fins 22 was set to 3.5 mm. Table 1
• the heat exchanger, intermediate heat exchanger and refrigeration cycle according to the present invention can be employed in a refrigeration system for use in, example, automobile air-conditioners.
• the terminology “present invention” or “invention” may be used as a reference to one or more aspect within the present disclosure.
• the language present invention or invention should not be improperly interpreted as an identification of criticality, should not be improperly interpreted as applying across all aspects or embodiments (i.e. , it should be understood that the present invention has a number of aspects and embodiments), and should not be improperly interpreted as limiting the scope of the application or claims.
• the terminology “embodiment” can be used to describe any aspect, feature, process or step, any combination thereof, and/or any portion thereof, etc. In some examples, various embodiments may include overlapping features. In this disclosure and during the prosecution of this case, the following abbreviated terminology may be employed: “e.g.” which means “for example;” and “NB” which means “note well.”

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Geometry (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Priority Applications (2)

Applications Claiming Priority (4)

Publications (1)

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• 2005
  • 2005-08-03 JP JP2005224926A patent/JP2006071270A/ja active Pending
  • 2005-08-05 US US11/571,893 patent/US20080066488A1/en not_active Abandoned
  • 2005-08-05 DE DE112005001885T patent/DE112005001885T5/de not_active Withdrawn
  • 2005-08-05 CN CNA2005800213825A patent/CN1977139A/zh active Pending
  • 2005-08-05 WO PCT/JP2005/014810 patent/WO2006014032A1/en active Application Filing

Patent Citations (2)

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