Classifications

• • 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
  • F28D1/053—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 straight
  • F28D1/0535—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 straight the conduits having a non-circular cross-section
  • F28D1/05366—Assemblies of conduits connected to common headers, e.g. core type radiators
  • F28D1/05383—Assemblies of conduits connected to common headers, e.g. core type radiators with multiple rows of conduits or with multi-channel conduits
• • 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
  • F25B39/02—Evaporators
  • F25B39/022—Evaporators with plate-like or laminated 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
  • 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
  • F28F1/325—Fins with openings
• • 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
  • F28D2001/0253—Particular components
  • F28D2001/026—Cores
  • F28D2001/0266—Particular core assemblies, e.g. having different orientations or having different geometric features
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F2260/00—Heat exchangers or heat exchange elements having special size, e.g. microstructures
  • F28F2260/02—Heat exchangers or heat exchange elements having special size, e.g. microstructures having microchannels

Definitions

• This invention relates generally to a microchannel heat exchanger that improves water shedding from a surface of tubes.
• MicroChannel heat exchangers can be used as a condenser in a refrigeration system.
• the microchannel heat exchanger includes horizontal tubes with a flattened surface that extend between two vertical headers.
• the flattened surface of the tubes is substantially horizontal, and water does not shed from fins effectively. Water sits on the tubes, decreasing heat transfer performance, causing an increase in pressure drop, and allowing the gradual build up of ice under frosting conditions. For this reason, microchannel heat exchangers have not been widely applied as evaporators or as outdoor coils for heat pumps.
• the tubes are oriented vertically to prevent the accumulation of water on the tubes. Any condensate that forms gradually drains through louvers in the fins of the microchannel heat exchanger. However, this is not optimal as the louvers are blocked by the water, reducing heat transfer performance.
• the length of the horizontal headers could be eight feet in length and must be bent several times to fit into a chassis. This creates manufacturing difficulties and reliability concerns and is more expensive than the vertical header/horizontal tube configuration.
• a heat exchanger includes a two headers and tubes that extend between the headers. Channels are defined in each of the tubes. Refrigerant flows through the channels of the tubes, and air that passes over the tubes exchanges heat with the refrigerant.
• the heat exchanger is a microchannel evaporator.
• Each tube has an elongated cross-section taken perpendicular to a length of the tubes, the cross-section of the tubes having a first end and an opposing second end.
• each tube is angled relative to the horizontal such that a line defined between the ends of each tube is angled relative to the horizontal. As the tubes are angled, water that collects on the tubes is directed away from the tubes.
• a plate fin directs water away from the tubes.
• the plate fin includes openings, and a louver including parallel vertical slots is located between each opening.
• Each tube is interference fit in one of the openings of the plate fin, positioning a louver between each of the tubes.
• Figure 1 illustrates a prior art refrigeration system
• Figure 2 illustrates a microchannel heat exchanger
• Figure 3 illustrates a cross-section of a tube of the microchannel heat exchanger
• Figure 4 illustrates a header of the microchannel heat exchanger
• Figure 5 illustrates a plate fin of the microchannel heat exchanger
• Figure 6 illustrates a cross-sectional view of a portion of the plate fin of Figure 5 showing a louver and a v-shaped channel;
• Figure 7 illustrates an alternate plate fin of the microchannel heat exchanger
• Figure 8 illustrates a cross-sectional view of the microchannel heat exchanger
• Figure 9 illustrates a cross-sectional view of another configuration of the microchannel heat exchanger.
• Figure 1 illustrates a refrigeration system 20 including a compressor 22, a first heat exchanger 24, an expansion device 26, and a second heat exchanger 28.
• Refrigerant circulates through the closed circuit refrigeration system 20.
• the refrigerant exits the compressor 22 at a high pressure and a high enthalpy and flows through the first heat exchanger 24, which acts as a condenser.
• the refrigerant rejects heat to air and is condensed into a liquid that exits the first heat exchanger 24 at a low enthalpy and a high pressure.
• a fan 30 directs the air through the first heat exchanger 24.
• the cooled refrigerant then passes through the expansion device 26, expanding the refrigerant to a low pressure.
• the refrigerant flows through the second heat exchanger 28, which acts as an evaporator.
• the refrigerant accepts heat from air, exiting the second heat exchanger 28 at a high enthalpy and a low pressure.
• a fan 32 blows air through the second heat exchanger 28.
• the refrigerant then flows to the compressor 22, completing the cycle.
• the first heat exchanger 24 accepts heat from the air and functions as an evaporator, and the second heat exchanger 28 rejects heat to the air and functions as a condenser.
• the heat exchangers 24 and 28 are microchannel heat exchangers 38.
• the microchannel heat exchanger 38 can be part of a refrigeration system 20 used with a microdevice or an automobile air conditioner.
• FIG. 2 shows the microchannel heat exchanger 38.
• the microchannel heat exchanger 38 includes two headers 40 and 42 that extend along an axis Y, and tubes 44 having a length that extend between the two headers 40 and 42 along an axis X.
• the tubes 44 include channels or openings 46 (shown in Figure 3).
• the headers 40 and 42 are substantially vertical, and the tubes 44 extend substantially horizontally between the headers 40 and 42.
• the refrigerant flows through the tubes 44 and exchanges heat with the air that flows over the tubes 44.
• the openings 46 can be substantially circular, rectangular, or have any shape or geometry.
• a cross-section of the tubes 44 taken perpendicular to the axis X has an elongated shape, such as a rectangle or oval.
• the tubes 44 can include an outer surface 36 with a flattened portion.
• the line A defined between the ends 48 and 50 of the tubes 44 extends at an angle B 0 relative to the horizontal.
• the first end 48 is a distance S from the ground G
• the opposing second end 50 is a distance R from the ground G. That is, the first end 48 is farther from the ground G than the opposing second end 50 is from the ground G (the first end 48 is higher than the second end 50).
• the tubes 44 are optimally angled to balance the competing effects of shedding water and airside pressure drop.
• Figure 4 shows the header 40. Although only the header 40 is illustrated and described, the header 42 also includes the same features.
• the tubes 44 extend into and out of the page along the axis X.
• Figure 5 shows a plate fin 52 including c-shaped collars 54 that each define an opening 64.
• the collars 54 create various different fin densities required for different applications.
• the collars 54 include a V-shaped channel 68 (shown in Figure 6) that surrounds and defines the opening 64.
• the openings 64 and the collars 54 extend at the angle B 0 relative to the horizontal.
• the plate fin 52 includes a first edge 70 and a second edge 72 that extend along the axis Y. The first edge 70 is continuous, and the second edge 72 is interrupted by the openings 64.
• An elongated surface 74 is defined between the first edge 70 and the openings 64.
• the elongated surface 74 is located on the side 70 near the second end 50 of the tubes 44 (the lower end of the tubes 44).
• the plate fin 52 also includes at least one louver 56 having parallel slots 58.
• the parallel slots 58 are vertical and extend along the axis Y.
• a louver 56 is located between each of the openings 64 and extend at the angle B 0 relative to the horizontal. That is, the louvers 56 and the openings 64 alternate along the axis Y.
• the second edge 72 is continuous and not interrupted by the openings 64.
• the material of the plate fin 52 completely surrounds the openings 64, and the collars 54 can have an oval or rectangular shape.
• the tubes 44 are laced in the openings 64 and received in the openings 64 with an interference fit. The tubes 44 are then brazed to the plate fin 52.
• louvers 56 extend upwardly relative to the first edge 70. In another example shown in Figure 8, the louvers 56 extend downwardly relative to the first edge 70.
• Each tube 44 is received in one of the openings 64 of the plate fin 52 with an interference fit, positioning a louver 56 between adjacent tubes 44 to improve heat transfer.
• the plate fin 52 is then brazed to the tubes 44.
• the microchannel heat exchanger 38 As refrigerant flows through the openings 46 in the tubes 44, it exchanges heat with the air that flows over the tubes 44. If the refrigerant is accepting heat from the air, the microchannel heat exchanger 38 is acting as an evaporator, and condensate can form on the surface of the tubes 44. As the tubes 44 are angled relative to the horizontal, water sheds from the tubes 44 and does not collect on the tubes 44. The collars 54 and the v- shaped channels 68 allow the water to flow towards the first edge 70 and then downwardly towards the bottom of the microchannel heat exchanger 38 along the elongated surface 74. The parallel slots 58 also direct water downwardly. Shedding water or condensate from the surface of the tubes 44 increases heat performance, does not cause an increase in pressure drop, and prevents the accumulation of ice.

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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 (4)

Applications Claiming Priority (1)

Publications (1)

Family

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Family Applications (1)

Country Status (4)

Cited By (4)

Families Citing this family (6)

Citations (5)

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• 2007
  • 2007-12-18 US US12/674,971 patent/US20110120177A1/en not_active Abandoned
  • 2007-12-18 WO PCT/US2007/087901 patent/WO2009078869A1/en active Application Filing
  • 2007-12-18 CN CN2007801019840A patent/CN101903736A/zh active Pending
  • 2007-12-18 EP EP07869412.2A patent/EP2235467A4/de not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (1)

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