EP2077429A1 - Échangeur de chaleur et dispositif de réfrigération - Google Patents

Échangeur de chaleur et dispositif de réfrigération Download PDF

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Publication number
EP2077429A1
EP2077429A1 EP07829000A EP07829000A EP2077429A1 EP 2077429 A1 EP2077429 A1 EP 2077429A1 EP 07829000 A EP07829000 A EP 07829000A EP 07829000 A EP07829000 A EP 07829000A EP 2077429 A1 EP2077429 A1 EP 2077429A1
Authority
EP
European Patent Office
Prior art keywords
oil
heat transfer
transfer tube
heat exchanger
grooves
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Withdrawn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
EP07829000A
Other languages
German (de)
English (en)
Other versions
EP2077429A4 (fr
Inventor
Shun Yoshioka
Hyunyoung Kim
Kazushige Kasai
Yoshio Oritani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daikin Industries Ltd
Original Assignee
Daikin Industries Ltd
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
Application filed by Daikin Industries Ltd filed Critical Daikin Industries Ltd
Publication of EP2077429A1 publication Critical patent/EP2077429A1/fr
Publication of EP2077429A4 publication Critical patent/EP2077429A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F28F1/40—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only inside 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
    • F25B39/00—Evaporators; Condensers
    • 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
    • F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
    • F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
    • F28D1/04—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits
    • F28D1/047—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits the conduits being bent, e.g. in a serpentine or zig-zag
    • F28D1/0477—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits the conduits being bent, e.g. in a serpentine or zig-zag the conduits being bent in a serpentine or zig-zag
    • 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
    • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
    • F28F1/24—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely
    • F28F1/32—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely the means having portions engaging further tubular elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/18—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
    • F28F13/185—Heat-exchange surfaces provided with microstructures or with porous coatings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F17/00—Removing ice or water from heat-exchange apparatus
    • F28F17/005—Means for draining condensates from heat exchangers, e.g. from evaporators
    • 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
    • F25B43/00—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat
    • F25B43/02—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat for separating lubricants from the refrigerant

Definitions

  • the present invention relates to a heat exchanger applied to a refrigeration system which performs a refrigeration cycle, and a refrigeration system including the heat exchanger.
  • the invention relates to measures to enhance heat transfer in the heat exchanger.
  • an air conditioner disclosed by Patent Document 1 includes a refrigerant circuit connecting a compressor, an outdoor heat exchanger, an expander, and an indoor heat exchanger.
  • the refrigerant circuit is filled with carbon dioxide as a refrigerant.
  • the refrigerant compressed to a critical pressure or higher flows through the outdoor heat exchanger.
  • the outdoor heat exchanger the refrigerant exchanges heat with outdoor air by dissipating heat into the outdoor air.
  • the refrigerant that dissipated heat in the outdoor heat exchanger is reduced in pressure in the expander, and then flows into the indoor heat exchanger.
  • the indoor heat exchanger the refrigerant exchanges heat with indoor air by absorbing heat from the indoor air to evaporate. As a result, the indoor air is cooled.
  • the refrigerant evaporated in the indoor heat exchanger is sucked into the compressor and recompressed.
  • lubricating oil (refrigeration oil) is used to smoothen the movement of sliding parts of the compressor.
  • the oil is contained in the refrigerant flowing through the refrigerant circuit. Therefore, when the refrigerant flows through the heat exchanger such as an evaporator and a radiator, the oil remaining unsolved in the refrigerant adheres to an inner wall of a heat transfer tube, and an oil film may be formed over the whole inner circumferential wall of the heat transfer tube. This has been disadvantageous because the oil film may disturb heat transfer between the refrigerant and the air, and may deteriorate heat transfer performance of the heat exchanger.
  • PAG polyalkylene glycol
  • the oil of this kind is less compatible with carbon dioxide, and therefore it is likely to form the oil film in the heat transfer tube of the heat exchanger. Therefore, in the heat exchanger applied to the refrigeration system using the carbon dioxide refrigerant, decrease in heat transfer performance derived from the generation of the oil film has been significant.
  • an object of the present invention is to prevent the decrease in heat transfer performance of the heat exchanger derived from the generation of the oil film on the inner wall surface of the heat transfer tube of the heat exchanger.
  • the present invention relates to a heat exchanger which is applied to a refrigeration system for performing a vapor compression refrigeration cycle and has a heat transfer tube (22).
  • a heat transfer tube (22) of the heat exchanger In the heat transfer tube (22) of the heat exchanger, an oil groove (25) for trapping and transporting oil in a refrigerant is formed in an inner wall surface of the heat transfer tube (22).
  • the oil groove (25) is formed in the inner wall surface of the heat transfer tube (22) in the heat exchanger.
  • oil contained in the refrigerant flowing through the heat transfer tube (22) is trapped in the oil groove (25) and transported through the oil groove (25).
  • the refrigerant flows through the heat transfer tube (22), the refrigerant passes a center part in the heat transfer tube (22), and the oil remaining unsolved in the refrigerant passes an outer part in the heat transfer tube (22). That is, the oil flows along the inner wall surface of the heat transfer tube (22), and forms an oil film on the whole inner wall surface of the heat transfer tube (22).
  • the oil groove (25) is formed in the inner wall surface of the heat transfer tube (22). Therefore, the oil covering the inner wall surface of the heat transfer tube (22) is drawn into the oil groove (25) by surface tension, and flows in the oil groove (25).
  • the present invention makes it possible to avoid the generation of the oil film on the inner wall surface of the heat transfer tube (22).
  • the oil groove (25) extends in an axial direction of the heat transfer tube (22).
  • the oil groove (25) is formed in the inner wall surface of the heat transfer tube (22) to extend in the axial direction of the heat transfer tube (22). That is, according to the present invention, the oil groove (25) extends in the same direction as the flow direction of the refrigerant. Therefore, when the oil is trapped in the oil groove (25) as described above, the oil smoothly flows in the oil groove (25) in the same direction as the refrigerant flowing outside the oil groove (25). Thus, the present invention allows suppression of the oil trapped in the oil groove (25) from flowing out of the oil groove (25).
  • a plurality of oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22) to be aligned at regular intervals in a circumferential direction of the heat transfer tube (22).
  • the plurality of oil grooves (25) extending in the axial direction of the heat transfer tube (22) are aligned at regular intervals in the circumferential direction of the inner wall surface of the heat transfer tube (22). Therefore, the oil film formed on the whole inner wall surface of the heat transfer tube (22) is easily trapped in the oil grooves (25). Further, the amounts of oil trapped in the oil grooves (25) are equalized, and the oil trapping effect of the oil grooves (25) is improved.
  • a plurality of V-shaped oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22) to be aligned in the axial direction of the heat transfer tube (22).
  • the plurality of V-shaped oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22).
  • the oil grooves (25) are aligned in the axial direction of the heat transfer tube (22) so that every oil groove (25) is oriented to one side in the axial direction.
  • the refrigerant trapped in the oil grooves (25) is collected toward the pointed ends of the V-shaped grooves, and then comes out of the oil grooves (25) and flows in the same direction as the refrigerant.
  • a lipophilic layer (27) made of a lipophilic material is formed on an inner wall surface of the oil groove (25).
  • the lipophilic layer (27) having lipophilicity is formed on the inner wall surface of the oil groove (25). Therefore, the oil in the heat transfer tube (22) is easily drawn into the oil groove (25), and the oil is effectively trapped in the oil groove (25).
  • an oil repellent layer (28) made of an oil repellent material is formed on part of the inner wall surface of the heat transfer tube (22) other than the oil groove (25).
  • the oil repellent layer (28) is formed on the inner wall surface of the heat transfer tube (22) outside the oil groove (25). Therefore, according to the present invention, the oil present at the outside of the oil groove (25) is repelled by the oil repellent layer (28) and easily drawn into the oil groove (25). As a result, the oil is efficiently trapped in the oil groove (25).
  • a plurality of heat transfer enhancement grooves (50) helically running in a circumferential direction of the heat transfer tube (22) for enhancing heat transfer are formed in the inner wall surface of the heat transfer tube (22).
  • the helical heat transfer enhancement grooves (50) are formed in the inner wall surface of the heat transfer tube (22). With the heat transfer enhancement grooves (50) thus formed, the surface area of the inner wall surface of the heat transfer tube (22) is increased, and the heat transfer performance of the heat exchanger is improved.
  • the oil groove (25) extends in the axial direction of the heat transfer tube (22) to intersect with the heat transfer enhancement grooves (50).
  • the oil groove (25) is formed in the inner wall surface of the heat transfer tube (22) to extend in the axial direction of the heat transfer tube (22) to intersect with the heat transfer enhancement grooves (50). That is, the oil groove (25) is formed to be connected with the plurality of heat transfer enhancement grooves (50). Therefore, even when the oil is accumulated in the heat transfer enhancement grooves (50), the oil can flow into the oil groove (25) through the heat transfer enhancement grooves (50). This avoids the generation of the oil film in the heat transfer enhancement grooves (50).
  • a plurality of oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22) to be aligned at regular intervals in the circumferential direction of the heat transfer tube (22).
  • the plurality of oil grooves (25) extending in the axial direction of the heat transfer tube (22) are aligned at regular intervals in the circumferential direction of the heat transfer tube (22). Therefore, the oil film formed on the whole inner wall surface of the heat transfer tube (22) is easily trapped in the oil grooves (25).
  • the amounts of oil trapped in the oil grooves (25) are equalized, and the oil trapping effect of the oil grooves (25) is improved.
  • the oil accumulated in the heat transfer enhancement grooves (50) can quickly be discharged into the oil grooves (25), so that the generation of the oil film in the heat transfer enhancement grooves (50) can be avoided with more reliability.
  • a width of an opening of the oil groove (25) is larger than a width of an opening of the heat transfer enhancement groove (50).
  • the width of the opening of the oil groove (25) is larger than the width of the opening of the heat transfer enhancement groove (50). Therefore, the oil is less likely to enter the heat transfer enhancement grooves (50), and the oil is more likely enter the oil groove (25). Thus, the oil trapping effect of the oil groove (25) is improved.
  • a depth of the oil groove (25) is equal to or larger than a depth of the heat transfer enhancement groove (50).
  • the depth of the oil groove (25) is equal to or larger than the depth of the heat transfer enhancement groove (50). Therefore, the oil accumulated in the heat transfer enhancement grooves (50) can easily flow into the oil groove (25).
  • the present invention relates to a refrigeration system including a refrigerant circuit (10) which performs a vapor compression refrigeration cycle, wherein carbon dioxide as a refrigerant and polyalkylene glycol as refrigeration oil circulate in the refrigerant circuit (10), and the refrigerant circuit (10) includes the heat exchanger (12, 13) of any one of the first to eleventh aspects of the invention.
  • the refrigerant is used as the refrigerant
  • polyalkylene glycol (APG) is used as the refrigeration oil for smoothening the compressor mechanism, and the like. Due to low compatibility of PAG to carbon dioxide, the refrigerant and the oil are likely to separate in the heat exchanger (12, 13), and the oil film is easily formed on the whole inner wall surface of the heat transfer tube (22). However, according to the present invention, the oil groove (25) for trapping and transporting the oil is formed in the inner wall surface of the heat transfer tube (22). Therefore, in this refrigeration system, the generation of the oil film can be avoided in advance, and the decrease in heat transfer performance of the heat exchanger (12, 13) can be prevented.
  • the oil groove (25) for trapping the oil is formed in the inner wall surface of the heat transfer tube (22). Therefore, in contrast to the conventional heat exchanger in which the oil film is formed on the whole inner wall surface of the heat transfer tube, and the heat transfer performance of the heat exchanger is decreased, the present invention makes it possible to suppress the generation of the oil film by trapping the oil flowing on the inner wall surface of the heat transfer tube (22) in the oil groove (25). As a result, a contact area between the inner wall surface and the refrigerant is increased in the heat transfer tube (22), and the heat transfer between the refrigerant and a heating medium can be enhanced. By preventing the generation of the oil film in this manner, increase in pressure loss in the heat transfer tube (22) derived from the generation of the oil film can also be prevented.
  • the oil trapped in the oil groove (25) flows through the oil groove (25) and is quickly discharged out of the heat exchanger. This makes it possible to prevent the accumulation of the oil in the heat exchanger, and return a sufficient amount of oil to the compressor mechanism, and the like, with reliability.
  • the oil groove (25) extends in the axial direction of the heat transfer tube (22). Therefore, the oil trapped in the oil groove (25) smoothly flows in the oil groove (25). This makes it possible to avoid the oil once trapped in the oil groove (25) from flowing out of the oil groove (25) and covering the inner wall surface of the heat transfer tube (22). Further, the oil accumulated in the oil groove (25) can quickly be discharged out of the heat exchanger through the oil groove (25).
  • a plurality of oil grooves (25) are aligned at regular intervals in the circumferential direction of the heat transfer tube (22). Therefore, according to the present invention, the oil present on the inner wall surface of the heat transfer tube (22) is easily drawn into the oil grooves (25), and the amounts of oil trapped in the oil grooves (25) can be equalized. Thus, the generation of the oil film described above can be prevented with more reliability.
  • a plurality of V-shaped oil grooves (25) are formed to provide an oil path in the heat transfer tube (22) with reliability, so that the oil can quickly be discharged out of the heat exchanger.
  • the present invention makes it possible to return a sufficient amount of oil to the compressor mechanism, and the like, with reliability.
  • the lipophilic layer (27) is formed on the inner wall surface of the oil groove (25). Therefore, the oil trapping effect of the oil groove (25) can be improved, and the generation of the oil film can be prevented with more reliability. Further, the trapped oil is reliably transported through the oil groove (25) so that it is discharged out of the heat exchanger.
  • the oil repellent layer (28) is formed on the inner wall surface of the heat transfer tube (22). Therefore, the oil which is about to cover the inner wall surface of the heat transfer tube (22) can be repelled and guided into the oil groove (25). Thus, the oil trapping effect of the oil groove (25) can further be improved.
  • the helical heat transfer enhancement grooves (50) are formed in the inner wall surface of the heat transfer tube (22). Therefore, the surface area of the inner wall surface of the heat transfer tube (22) is increased, and the heat transfer performance of the heat transfer tube (22) can further be improved.
  • the oil groove (25) extends in the axial direction of the heat transfer tube (22) to intersect with the helical heat transfer enhancement grooves (50). Therefore, the oil accumulated in the heat transfer enhancement grooves (50) can be discharged into the oil groove (25). Thus, the generation of the oil film in the heat transfer enhancement grooves (50) can be avoided, and the decrease in heat transfer performance of the heat transfer tube (22) can be prevented.
  • a plurality of oil grooves (25) are aligned at regular intervals in the circumferential direction of the heat transfer tube (22). Therefore, according to the present invention, the oil present on the inner wall surface of the heat transfer tube (22) is easily drawn into the oil groove (25), and the amounts of oil trapped in the oil grooves (25) can be equalized. Thus, the generation of the oil film on the inner wall surface of the heat transfer tube (22) can be prevented with more reliability. Further, since the oil accumulated in the heat transfer enhancement grooves (50) can quickly be discharged into the oil grooves (25), the generation of the oil film in the heat transfer enhancement grooves (50) can also be prevented with reliability.
  • the width of the opening of the oil groove (25) is larger than the width of the opening of the heat transfer enhancement groove (50). Therefore, the oil in the heat transfer tube (22) can actively be drawn into the oil grooves (25).
  • the depth of the oil grooves (25) is equal to or larger than the depth of the heat transfer enhancement grooves (50). Therefore, the oil trapped in the heat transfer enhancement grooves (50) can reliably be discharged into the oil grooves (25).
  • the heat transfer can sufficiently be enhanced by the heat transfer enhancement grooves (50), and the heat transfer performance of the heat transfer tube (22) can further be improved.
  • PAG which is less compatible with carbon dioxide can be trapped in the oil groove (25). That is, according to the present invention, in contrast to the conventional refrigeration system in which the oil film is easily formed on the inner wall surface of the heat transfer tube, the generation of the oil film can be prevented with reliability, and sufficient heat transfer performance of the heat exchanger (12, 13) can be obtained with reliability.
  • a heat exchanger according to Embodiment 1 of the present invention is applicable to a refrigeration system (1) which performs a vapor compression refrigeration cycle.
  • the refrigeration system (1) of Embodiment 1 constitutes an air conditioner (1) capable of performing switchable cooling and heating of indoor air.
  • the air conditioner (1) includes a refrigerant circuit (10) filled with a refrigerant.
  • the refrigerant circuit (10) is filled with carbon dioxide as the refrigerant.
  • polyalkylene glycol (PAG) which is oil having polarity, is used as lubricating oil (refrigeration oil) for smoothening sliding parts of a compressor (11).
  • PAG flows through the refrigerant circuit (10) together with the refrigerant discharged from the compressor (11). Therefore, carbon dioxide as the refrigerant and PAG as the refrigeration oil circulate in the refrigerant circuit (10).
  • the refrigerant circuit performs a refrigeration cycle by compressing carbon dioxide to a critical pressure or higher (a so-called supercritical cycle).
  • the refrigerant circuit (10) includes a compressor (11), an outdoor heat exchanger (12), an indoor heat exchanger (13) and an expansion valve (14).
  • the compressor (11) may be, for example, a scroll compressor.
  • the compressor (11) is connected to a discharge pipe (11a) into which the refrigerant discharged from the compressor mechanism flows, and a suction pipe (11b) into which the refrigerant to be sucked into the compressor mechanism flows.
  • the outdoor heat exchanger (12) is placed in outdoor space. In the outdoor heat exchanger (12), the refrigerant flowing therein exchanges heat with outdoor air.
  • the indoor heat exchanger (13) is placed in indoor space. In the indoor heat exchanger (13), the refrigerant flowing therein exchanges heat with indoor air.
  • the outdoor heat exchanger (12) and the indoor heat exchanger (13) are heat exchangers of the present invention and constitute cross-fin heat exchangers, respectively.
  • the expansion valve (14) is connected between the outdoor heat exchanger (12) and the indoor heat exchanger (13).
  • the expansion valve (14) may be, for example, an electronic expansion valve.
  • a four-way switching valve (15) is also arranged in the refrigerant circuit (10).
  • the four-way switching valve (15) has first to fourth ports. In the four-way switching valve (15), the first port is connected to the outdoor heat exchanger (12), the second port is connected to a suction side of the compressor (11), the third port is connected to a discharge side of the compressor (11), and the fourth port is connected to the indoor heat exchanger (13).
  • the four-way switching valve (15) is switchable between a first state in which the first and third ports communicate with each other, and the second and fourth ports communicate with each other (a state depicted by a solid line in FIG. 1 ), and a second state in which the first and second ports communicate with each other, and the third and fourth ports communicate with each other (a state depicted by a broken line in FIG. 1 ).
  • each of the heat exchangers (12, 13) includes a plurality of fins (21) and a heat transfer tube (22).
  • Each of the fins (21) is made of aluminum and in the shape of a rectangular plate.
  • the fins (21) are arranged parallel to each other at predetermined intervals.
  • the heat transfer tube (22) is made of a copper tube.
  • the heat transfer tube (22) includes a plurality of straight portions (22a) and curved portions (22b) connecting the straight portions (22a).
  • Each of the straight portions (22a) extends in the arrangement direction of the fins (21) and penetrates the fins (21).
  • the curved portions (22b) are attached to the fin (21) at the front end and the fin (21) at the back end among the plurality of fins (21, 21, ).
  • Each of the curved portions (22b) is curved to connect the ends of two linear portions (22a).
  • a plurality of oil grooves (25) for trapping and transporting the oil in the refrigerant are formed in an inner wall surface of the heat transfer tube (22) in each of the heat exchangers (12, 13).
  • four oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22).
  • the oil grooves (25) are formed in both of the straight portions (22a) and the curved portions (22b).
  • the oil grooves (25) may be formed only in the straight portions (22a).
  • Each of the oil grooves (25) is defined by a pair of inclined surfaces (25a, 25a) inclined to separate from each other in a radially inward direction of the heat transfer tube (22), and a bottom surface (25b) formed between the inclined surfaces (25a, 25a). That is, when viewed in longitudinal section, each of the oil grooves (25) is in the shape of a trapezoid so that an opening area thereof is increasing in the radially inward direction of heat transfer tube (22).
  • each of the oil grooves (25) extends in the axial direction of the heat transfer tube (22). That is, the oil grooves (25) are formed along the flow direction of the refrigerant in the heat transfer tube (22).
  • the oil grooves (25) are arranged at regular intervals in the circumferential direction of the heat transfer tube (22). Specifically, the oil grooves (25) are arranged at angular intervals of 90° in the circumferential direction of the heat transfer tube (22).
  • the ratio (S2/S1) of the total longitudinal sectional area S2 of the oil grooves (25) to the longitudinal sectional area S1 of the heat transfer tube (22) is preferably 0.01 to 0.2, both inclusive.
  • the circulating direction of the refrigerant is changed by the setting of the four-way switching valve (15).
  • the four-way switching valve (15) is set to the state indicated by the solid line in FIG. 1 .
  • a refrigeration cycle is performed in which the outdoor heat exchanger (12) functions as a radiator, and the indoor heat exchanger (13) functions as an evaporator.
  • the four-way switching valve (15) is set to the state indicated by the broken line in FIG. 1 .
  • the refrigerant compressed to a critical pressure or higher in the compressor (11) is discharged from the discharge pipe (11a).
  • oil used to smoothen the sliding parts of the compressor is discharged together with the high pressure refrigerant from the compressor (11).
  • the refrigerant flows into the outdoor heat exchanger (12).
  • the high pressure refrigerant dissipates heat into outdoor air.
  • the high pressure refrigerant that dissipated heat into the outdoor heat exchanger (12) is reduced in pressure as it passes through the expansion valve (14), and converted to a low pressure refrigerant.
  • the refrigerant flows into the indoor heat exchanger (13).
  • the refrigerant absorbs heat from indoor air and evaporates. As a result, the indoor air is cooled.
  • the refrigerant evaporated in the indoor heat exchanger (13) flows through the suction pipe (11b) to be sucked into the compressor (11), and is recompressed.
  • the heat transfer performance of the heat exchangers is significantly decreased, and the cooling and heating capacities of the air conditioner are also decreased.
  • the oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22) to trap the oil in the oil grooves (25) for the purpose of preventing the decrease in heat transfer performance derived from the generation of the oil film.
  • oil-containing refrigerant flows through the indoor heat exchanger (13) in the above-described cooling operation
  • an evaporated gaseous refrigerant (40) flows in a center part of the heat transfer tube (22)
  • a liquid refrigerant (41) flows outside the gaseous refrigerant (40), as shown in FIG. 6 .
  • Oil (42) which is relatively high in viscosity and density flows outside the liquid refrigerant (41) on the inner wall surface of the heat transfer tube (22). Since the above-described oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22), the oil (42) is drawn into the oil grooves (25) by surface tension, and trapped in the oil grooves (25).
  • the above-described oil film is hardly generated on the inner wall surface of the heat transfer tube (22), and the liquid refrigerant (41) and the inner wall surface of the heat transfer tube (22) are brought into direct contact.
  • the indoor heat exchanger (13) heat transfer between the indoor air and the liquid refrigerant is enhanced, and the liquid refrigerant evaporates with efficiency.
  • the oil trapped in the oil grooves (25) flows in the oil grooves (25) in the same direction as the gaseous refrigerant (40) and the liquid refrigerant. Then, the oil is quickly discharged out of the indoor heat exchanger (13) together with the refrigerant.
  • the oil grooves (25) for trapping the oil are formed in the inner wall surface of the heat transfer tube (22). Therefore, in contrast to the conventional heat exchanger in which the oil film is formed on the whole inner wall surface of the heat transfer tube, and the heat transfer performance of the heat exchanger is decreased, the generation of the oil film can be suppressed by trapping the oil flowing on the inner wall surface of the heat transfer tube (22) in the oil grooves (25) of Embodiment 1. As a result, the decrease in heat transfer performance derived from the generation of the oil film can be prevented. Further, by preventing the generation of the oil film in this manner, increase in pressure loss in the heat transfer tube (22) derived from the generation of the oil film can also be prevented.
  • the oil grooves (25) extend in the axial direction of the heat transfer tube (22). Therefore, the oil trapped in the oil grooves (25) smoothly flows in the oil grooves (25). This makes it possible to avoid the oil once trapped in the oil grooves (25) from flowing out of the oil grooves (25) and covering the inner wall surface of the heat transfer tube (22). Further, the oil accumulated in the oil grooves (25) can quickly be discharged out of the heat exchanger through the oil grooves (25). Thus, the oil can be avoided from remaining in the heat exchanger (12, 13), and lack of oil returning to the compressor (11) can be avoided.
  • a plurality of oil grooves (25) are arranged at angular intervals of 90° in the circumferential direction of the heat transfer tube (22). Therefore, according to Embodiment 1, the oil present on the inner wall surface of the heat transfer tube (22) is easily drawn into the oil grooves (25), and the amounts of oil trapped in the oil grooves (25) can be equalized. Thus, the generation of the oil film described above can be prevented with more reliability.
  • Heat exchangers (12, 13) according to Embodiment 2 of the present invention are different from those of Embodiment 1 in the structure of the heat transfer tube (22). Specifically, as shown in FIG. 7 , the heat transfer tube (22) of Embodiment 2 is provided with more oil grooves (25) than those formed in Embodiment 1. In the same manner as Embodiment 1, the oil grooves (25) extend in the axial direction of the heat transfer tube (22).
  • a lipophilic layer (27) made of a lipophilic material is applied to the bottom surface (25b) of each of the oil grooves (25).
  • the lipophilic material constituting the lipophilic layer (27) may be water glass, acrylic, an epoxy resin, polyvinyl alcohol, and other materials.
  • an oil repellent layer (28) made of an oil repellent material is applied on the inner wall surface of the heat transfer tube (22) outside the oil grooves (25).
  • Examples of the oil repellent material constituting the oil repellent layer (28) may be materials based on polytetrafluoroethylene (so-called Teflon ® ), fluorine, paraffin, and silicon.
  • the generation of the oil film on the inner wall surface of the heat transfer tube (22) can also be prevented by forming the oil grooves (25) in the heat transfer tube (22). Further, the lipophilic layer (27) is formed on the inner wall surface of each of the oil grooves (25), and the oil repellent layer (28) is formed on part of the inner wall surface of the heat transfer tube (22) outside the oil grooves (25). Therefore, according to Embodiment 2, the oil trapping effect of the oil grooves (25) can be improved, and the generation of the oil film can be prevented with more reliability. Further, according to Embodiment 2, the trapped oil can reliably be transported through the oil grooves (25) and discharged out of the heat exchanger.
  • Only one of the lipophilic layer (27) and the oil repellent layer (28) of Embodiment 2 may be formed in the heat transfer tube (22).
  • the lipophilic layer (27) may be formed on the inclined surfaces (25a) of the oil grooves (25). Further, the lipophilic layer (27) and the oil repellent layer (28) of Embodiment 2 may be applied to the heat exchangers (12, 13) of Embodiment 1.
  • Heat exchangers (12, 13) according to Embodiment 3 of the present invention are different from those of Embodiments 1 and 2 in the structure of the heat transfer tube (22). Specifically, as shown in FIG. 9 , a plurality of V-shaped oil grooves (25) are formed in the inner wall surface of the heat transfer tube (22) of Embodiment 3. Each of the V-shaped oil grooves (25) is formed by connecting the ends of a pair of grooves (25c, 25c) running at an angle to the axial direction of the heat transfer tube (22). The oil grooves (25) are aligned at predetermined intervals in the axial direction of the heat transfer tube (22).
  • the oil grooves (25) are formed so that a pointed end (25d) of each of the V-shaped grooves (25), at which the pair of grooves (25c, 25c) are connected, is directed to a discharge side in the flow direction of the refrigerant in the heat transfer tube (22). That is, the pointed ends (25d) of the oil grooves (25) are oriented to one side in the axial direction of the heat transfer tube (22).
  • a group of the aligned oil grooves (25) is connected to another group of the aligned oil grooves (25) adjacent thereto in the circumferential direction, so that a so-called plurality of W-shaped grooves are formed in the heat transfer tube (22).
  • Embodiment 3 the generation of the oil film on the inner wall surface of the heat transfer tube (22) can be prevented by forming the oil grooves (25) in the heat transfer tube (22).
  • a plurality of V-shaped oil grooves (25) are formed to reliably form a flow path of the trapped oil, so that the oil can quickly be discharged out of the heat exchanger (12, 13).
  • Embodiment 3 makes it possible to reliably avoid the lack of oil returning to the compressor (11).
  • Heat exchangers (12, 13) according to Embodiment 4 of the present invention are different from those of Embodiments described above in the structure of the heat transfer tube (22). Specifically, as shown in FIGS. 11 to 14 , a plurality of heat transfer enhancement grooves (50) are formed in the inner wall surface of the heat transfer tube (22) of Embodiment 4.
  • the heat transfer enhancement grooves (50) are helically running in the circumferential direction of the heat transfer tube (22) and parallel to each other.
  • the longitudinal section of the heat transfer enhancement groove (50) is substantially in the shape of a trapezoid or a triangle, in which the opening area of the groove is increasing toward the opening end.
  • the oil grooves (25) extend in the axial direction of the heat transfer tube (22) and arranged at angular intervals of 90° in the circumferential direction of the heat transfer tube (22).
  • the oil grooves (25) may not always extend linearly, and they may extend at a helix angle of 0 to 5 degrees.
  • the longitudinal section of the oil groove (25) is substantially in the shape of a trapezoid, in which the opening area of the groove is increasing toward the opening end.
  • Each of the oil grooves (25) intersects with the plurality of heat transfer enhancement grooves (50) by crossing them. That is, as shown in FIG. 13 (a perspective view illustrating an enlargement of the inner wall surface of the heat transfer tube), the helical heat transfer enhancement grooves (50) are connected to the oil grooves (25) at both lengthwise ends.
  • a width W1 of the opening of the oil groove (25) is larger than a width W2 of the opening of the heat transfer enhancement groove (50).
  • a depth D1 of the oil groove (25) is the same as a depth D2 of the heat transfer enhancement groove (50). However, the depth D1 may be larger than the depth D2, or the depth D1 may be equal to or larger than the depth D2.
  • the width W1 of the opening of the oil groove (25) is suitably in the range of 0.2 mm to 1.0 mm.
  • oil (42) in the heat transfer tube (22) enters the oil grooves (25).
  • the oil (42) may enter the heat transfer enhancement grooves (50), but it flows through the heat transfer enhancement grooves (50) and is discharged into the oil grooves (25) (see FIG. 13 ). Therefore, the generation of the oil film in the heat transfer enhancement grooves (50) is prevented. In this way, the oil (42) trapped in the oil grooves (25) is discharged out of the heat exchanger (12, 13) through the oil grooves (25).
  • the helical heat transfer enhancement grooves (50) are formed in the inner wall surface of the heat transfer tube (22). Therefore, the surface area of the inner wall surface of the heat transfer tube (22) is increased, and the heat transfer performance of the heat transfer tube (22) can further be improved. Further, since the oil grooves (25) extending in the axial direction of the heat transfer tube (22) intersect with the helical heat transfer enhancement grooves (50), the oil accumulated in the heat transfer enhancement grooves (50) can be discharged to the oil grooves (25). Therefore, the generation of the oil film in the heat transfer enhancement grooves (50) can be avoided, and the decrease in heat transfer performance of the heat transfer tube (22) can be prevented.
  • the four oil grooves (25) are aligned at equal intervals in the circumferential direction of the heat transfer tube (22). Therefore, the oil present on the inner wall surface of the heat transfer tube (22) is easily drawn into the oil grooves (25), and the amounts of oil trapped in the oil grooves (25) can be equalized. Thus, the generation of the oil film on the inner wall surface of the heat transfer tube (22) can be prevented with more reliability. Moreover, since the oil accumulated in the heat transfer enhancement grooves (50) can quickly be discharged to the oil grooves (25), the generation of the oil film in the heat transfer enhancement grooves (50) can also be prevented with reliability.
  • the width W1 of the opening of the oil groove (25) is larger than the width W2 of the opening of the heat transfer enhancement groove (50). Therefore, the oil in the heat transfer tube (22) can actively be drawn into the oil grooves (25). Further, since the depth D1 of the oil grooves (25) is equal to or larger than the depth D2 of the heat transfer enhancement grooves (50), the oil trapped in the heat transfer enhancement grooves (50) can reliably be discharged into the oil grooves (25). Thus, the heat transfer can sufficiently be enhanced by the heat transfer enhancement grooves (50), and the heat transfer performance of the heat transfer tube (22) can further be improved.
  • the shape of the oil groove (25) formed in the inner wall surface of the heat transfer tube (22) may be different from those described in the above-described embodiments.
  • the oil groove (25) may be a helical or serpentine groove, or the longitudinal section of the oil groove (25) may be in the shape of a triangle, an oval, or a semicircle.
  • the number of the oil grooves (25) is not limited to four.
  • the number of the oil grooves may be one, or more than four.
  • the heat exchangers (12, 13) of the present invention are applied to the refrigeration system in which carbon dioxide is used as the refrigerant, and PAG is used as the refrigeration oil.
  • the heat exchangers (12, 13) may be applied to a refrigeration system using a refrigerant and refrigeration oil other than those described above.
  • the refrigerant may be R134a, R410a, R407c, R32, or other refrigerants
  • the refrigeration oil may be poly- ⁇ -olefine, P06, fluorine-based oils, or other oils.
  • the present invention is useful for heat exchangers applied to refrigeration systems that perform a refrigeration cycle.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
EP07829000.4A 2006-10-18 2007-10-02 Échangeur de chaleur et dispositif de réfrigération Withdrawn EP2077429A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2006283802 2006-10-18
JP2007133988A JP2008122059A (ja) 2006-10-18 2007-05-21 熱交換器及び冷凍装置
PCT/JP2007/069260 WO2008050587A1 (fr) 2006-10-18 2007-10-02 Échangeur de chaleur et dispositif de réfrigération

Publications (2)

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EP2077429A1 true EP2077429A1 (fr) 2009-07-08
EP2077429A4 EP2077429A4 (fr) 2014-05-07

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EP (1) EP2077429A4 (fr)
JP (1) JP2008122059A (fr)
CN (1) CN101523149B (fr)
WO (1) WO2008050587A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8904812B2 (en) 2010-02-10 2014-12-09 Mitsubishi Electric Corporation Refrigeration cycle apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103968589B (zh) * 2010-02-10 2016-05-25 三菱电机株式会社 冷冻循环装置
CN111457627B (zh) 2014-03-31 2022-12-02 特灵国际有限公司 制冷系统中的疏亲结构和制冷系统中的液体蒸汽分离
WO2023188387A1 (fr) * 2022-03-31 2023-10-05 三菱電機株式会社 Dispositif à cycle frigorifique

Citations (4)

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Publication number Priority date Publication date Assignee Title
EP0753709A2 (fr) * 1995-07-12 1997-01-15 Sanyo Electric Co., Ltd. Echangeur de chaleur pour circuit frigorifique
JPH1194481A (ja) * 1997-09-25 1999-04-09 Gac Kk 熱交換器用チューブおよび熱交換器
US20030167793A1 (en) * 2002-03-08 2003-09-11 Tomoo Honda Vapor-compression type refrigerating machine and heat exchanger therefor
EP1389721A1 (fr) * 2001-05-23 2004-02-18 Matsushita Electric Industrial Co., Ltd. Dispositif a cycle de refrigeration

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JPH06300372A (ja) * 1993-04-12 1994-10-28 Matsushita Refrig Co Ltd 冷凍装置
JP3751393B2 (ja) * 1997-01-17 2006-03-01 株式会社コベルコ マテリアル銅管 管内面溝付伝熱管
JP2001116371A (ja) 1999-10-20 2001-04-27 Daikin Ind Ltd 空気調和装置
JP4597475B2 (ja) * 2002-12-12 2010-12-15 住友軽金属工業株式会社 熱交換器用クロスフィンチューブの製造方法及びクロスフィン型熱交換器

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Publication number Priority date Publication date Assignee Title
EP0753709A2 (fr) * 1995-07-12 1997-01-15 Sanyo Electric Co., Ltd. Echangeur de chaleur pour circuit frigorifique
JPH1194481A (ja) * 1997-09-25 1999-04-09 Gac Kk 熱交換器用チューブおよび熱交換器
EP1389721A1 (fr) * 2001-05-23 2004-02-18 Matsushita Electric Industrial Co., Ltd. Dispositif a cycle de refrigeration
US20030167793A1 (en) * 2002-03-08 2003-09-11 Tomoo Honda Vapor-compression type refrigerating machine and heat exchanger therefor

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Title
See also references of WO2008050587A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8904812B2 (en) 2010-02-10 2014-12-09 Mitsubishi Electric Corporation Refrigeration cycle apparatus
US9285142B2 (en) 2010-02-10 2016-03-15 Mitsubishi Electric Corporation Refrigeration cycle apparatus

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EP2077429A4 (fr) 2014-05-07
JP2008122059A (ja) 2008-05-29
CN101523149B (zh) 2011-02-16
WO2008050587A1 (fr) 2008-05-02
CN101523149A (zh) 2009-09-02

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