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
  • F28F1/12—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
• • 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
  • F28F1/02—Tubular elements of cross-section which is non-circular
  • F28F1/022—Tubular elements of cross-section which is non-circular with multiple channels
• • 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
  • F28F1/126—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 consisting of zig-zag shaped fins
  • F28F1/128—Fins with openings, e.g. louvered fins
• • 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
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F3/00—Plate-like or laminated elements; Assemblies of plate-like or laminated elements
  • F28F3/02—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations
  • F28F3/025—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations the means being corrugated, plate-like elements
  • F28F3/027—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations the means being corrugated, plate-like elements with openings, e.g. louvered corrugated fins; Assemblies of corrugated strips
• • 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

Definitions

• the subject matter disclosed herein relates to heat exchangers. More specifically, the subject disclosure relates to fin and tube configurations for microchannel heat exchangers.
• Heating, ventilation, air conditioning and refrigeration (HVAC & R) systems include heat exchangers to reject or accept heat between the refrigerant circulating within the system and surroundings.
• One type of the heat exchanger that has become increasingly popular, due to its compactness, structural rigidity and superior performance is a microchannel or minichannel heat exchanger (MCHX) which includes two or more containment forms, such as tubes, through which a cooling or heating fluid (such as refrigerant or glycol solution) is circulated.
• the tubes typically have a flattened cross-section and multiple parallel channels. Fins are typically arranged to extend between the tubes to aid in the transfer of thermal energy between the cooling/heating fluid and the surrounding environment.
• the fins have a corrugated pattern, incorporate louvers to boost heat transfer and are typically secured to the tubes via brazing.
• Typical MCHX fin and tube arrangements have the disadvantage of retaining large quantities of moisture, water or condensate, within the fin and tube structure, due to their high compactness and thus increased surface tension. The accumulated moisture accelerates corrosion of the fin and tube structure which leads to decreased thermo-hydraulic performance or effectiveness of the heat exchanger and eventual failure of the heat exchanger when the tubes are corroded sufficiently to be perforated, thus releasing the cooling/heating fluid.
• the typical structure leads to the buildup of corrodant substances and mechanical stresses in the structure leading to stress corrosion which further accelerates deterioration of the fin and tube structure and resultant failure of the heat exchanger.
• the art would well receive a fin and tube structure which reduces the accumulation of moisture in the heat exchanger matrix thereby reducing corrosion of the heat exchanger.
• a heat exchanger includes a plurality of tubes, each tube configured for a flow of fluid therethrough and one or more fins located between adjacent tubes of the plurality of tubes.
• the one or more fins are spaced by a fin pitch (Fp) and are configured to improve thermal energy transfer between the plurality of tubes and ambient air.
• Each fin includes a fin face extending between the adjacent tubes, a substantially planar fin cap connected to the fin face secured to one or the tubes, and a fin radius (Rc) connecting the fin face to the fin cap such that the fin radius is minimized to promote removal of condensate from the heat exchanger.
• a heat exchanger includes a plurality of tubes, each tube configured for a flow of fluid therethrough.
• One or more fins are located between adjacent tubes of the plurality of tubes.
• the one or more fins are spaced by a fin pitch (F P ) and are configured to improve thermal energy transfer between the plurality of tubes and ambient air.
• Each fin includes a fin extension extending beyond a tube width. The extended portion of the fin is laterally flared and shaped to reduce capillary effects and enhance water drainage.
• FIG. 1 is cross-sectional view of an embodiment of a heat exchanger
• FIG. 2 is another cross-sectional view of an embodiment of a heat exchanger illustrating a fin face, fin cap, fin radius and louver of the heat exchanger;
• FIG. 3 is a cross-sectional view of an embodiment of a heat exchanger illustrating a fin extension
• FIG. 4 is a cross-sectional view of an embodiment of a heat exchanger including multiple heat exchanger tubes
• FIG. 5 is a cross-sectional view of an embodiment of a heat exchanger including a fin notch
• FIG. 6 is a perspective view of an embodiment of a heat exchanger including a fin notch
• FIG. 7 is a perspective view of an embodiment of a slotted heat exchanger tube.
• FIG. 8 is a cross-sectional view of a welded slotted heat exchanger tube.
• FIG. 1 Shown in FIG. 1 is an embodiment of a tube and fin arrangement of a heat exchanger 10.
• the heat exchanger 10 includes a plurality of tubes 12.
• Each tube 12 in the embodiment shown includes multiple channels 14 through which cooling fluid is circulated.
• each tube includes sixteen channels 14, but it is to be appreciated that any number of channels 14 may be utilized.
• a plurality of fins 16 extend between the tubes 12 to aid in increasing heat transfer between the tubes 12 and the surrounding air.
• the fins 16 are secured to the tubes 12 by, for example, brazing, or other suitable means such as for instance soldering or gluing, and in some embodiments, the fins 16 may have a fin thickness (F TH ) of between about 50 and about 100 microns.
• F TH fin thickness
• the fin thickness is merely exemplary, and other fin thicknesses outside of the described range may be utilized within the scope of the present disclosure.
• the heat exchanger 10 of FIG. 1 is typically a horizontal tube heat exchanger of the type used in, for example, air conditioning condenser applications. It is to be appreciated that other tube orientations are feasible and within the scope of the invention.
• the fins 16 are arranged along the tubes 12 and spaced from each other at a fin pitch (Fp) 18.
• the fins 16 of some embodiments are folded or corrugated fins 16.
• the fin 16 includes a fin face 20 extending between the tubes 12 at a fin angle 74 which, in some embodiments, is nonperpendicular to the tubes 12, and a fin cap 22 disposed at each end of the fin face 20 at the tubes 12 and extending along the tubes 12.
• the fin 16 is secured to the tubes 12 at the fin cap 22.
• the fin cap 22 is substantially planar, and in some embodiments, the fin face 20 is also substantially planar.
• Each fin face 20 includes a plurality of through openings, for example, louvers 24 arrayed along a lateral extent of the fin 16.
• the louvers 24 improve heat transfer and also assist in reducing water retention in the heat exchanger by providing an alternate passage for moisture, water, and/or condensate to drain through the heat exchanger 10.
• a transition between each fin cap 22 and fin face 20 is a fin radius (R c ) 26. It is desired to reduce the fin radius 26 in order for a louver height (L H ) 28 to be increased relative to a fin height (F H ) 30, thus increasing an overall size of the louver 24 opening within the fin 16.
• a ratio of louver height 28 to fin height 30, L H /F H is between about 0.8 and about 0.95, and the preferred range is between about 0.85 and about 0.92.
• the fin radius 26 relates to fin pitch 18 such that a ratio of fin radius 26 to fin pitch 18, Rc/Fp, is between about 0.1 and about 0.4.
• the preferred range of Rc/F P is between about 0.2 and about 0.3
• a fin width (Fw) 32 extends beyond a tube width 34 by an extension 36 at at least one tube side 38, and in some embodiments, both tube sides 38.
• the extension 36 extends laterally away from the tube side 38 as well as transversely at least partially across a tube thickness 40.
• the resulting extension 36 extends upwardly or downwardly in a horizontal tube 12 heat exchanger 10, and may be substantially linear or planar in profile, or in other embodiments may be substantially arcuate, a combination of linear and arcuate or other profile.
• the extension 36 may comprise two planar extension portions 74, and further, the extension 36 may have a substantially squared-off cross- section.
• the squared-off cross section is merely exemplary and other cross-sectional shapes are contemplated within the scope of the present disclosure. Extending the extensions 36 upwardly or downwardly reduces surface tension effects and utilizes gravitational forces to encourage flow of condensate 42 away from the tubes 12 thereby reducing corrosion of the tubes 12. To achieve the desired drainage, it is not required that an extension width (E w ) 44 be overly large relative to the overall fin width (F w ) 32.
• a ratio of extension width 44 to fin width 32, Ew Fw is between about 0.02 and about 0.1, while the preferred Ew Fw range is between about 0.02 and about 0.04, to enhance the desired drainage effect while minimizing the amount of space utilized by the fins 16.
• a transverse component (E T ) 48 of the extension 36 does not need to be overly great appreciable relative to the tube thickness ( ⁇ ) 40 to produce the desired effect.
• a ratio of the transverse component 48 to the tube thickness 40, ⁇ / ⁇ is between about 0.05 and about 0.4, while the preferred E T /T T range is between about 0.05 and about 0.15.
• the transverse component 48 be relatively large when compared to a fin thickness (F T ) 50 (shown in FIG. 2).
• a ratio between the transverse component 48 and the fin thickness 50, ⁇ /Fx is between about 1 and about 3, while the preferred ⁇ /Fx range is between about 1.75 and about 2.5.
• the transverse component 48 is related to the fin radius 26, such that a ratio of the transverse component 48 to the fin radius, E T /R C , is between about 0.2 and about 2.
• each fin 16 spans two or more tubes 12 located at each fin cap 22 with a gap (T G ) 52 between adjacent tubes 12.
• some embodiments include a fin notch 54 substantially aligned with the tube gap 52.
• a ratio of the notch height 58 to the tube pitch 56, N H /(T P -T T ) is about 0.15 to about 0.3.
• N H /(T P -T T ) is about 0.1 to about 0.2 to encourage moisture flow outward toward the extensions 36.
• each fin notch 54 has a notch width (Nw) 60 extending in a direction along the length of the tube 12.
• the notch width 60 is sized relative to the fin pitch 18, the fin height 30, and the tube pitch 56 in order to maximize the gravitational effects and reduction in surface tension desired. The relationship is expressed as follows:
• the relationship equals about 0.3 to about 0.9, while the preferred range of the relationship is about 0.4 to about 0.7.
• FIG. 7 Another embodiment is illustrated in FIG. 7.
• the embodiment of FIG. 7 illustrates a tube 12 including a tube slot 62 extending therethrough.
• the tube slot 62 defines an additional egress location for moisture, condensate, and/or water from the heat exchanger 10.
• the slot 62 has a slot width (Sw) 66.
• a ratio of the slot width 66 to a tube width (Tw) 68, Sw Tw, is between about 0.05 and about 0.2 to provide the moisture egress while not significantly reducing an amount of fluid the tube 12 is capable of carrying or effecting heat transfer and pressure drop characteristics of heat exchanger 10.
• the slot 62 has a slot length (S L ) 70 extending along a tube length (T L ) 72 of the tube 12.
• the slotted tube 12 may include one or more refrigerant inlets 74 and one or more refrigerant outlets 76, and may be connected to one or more coolant manifolds 78 at either end of the tube length 72.
• the slotted tube 12 may be formed one of many ways including extrusion of the slotted tube 12.
• the slot 62 may be formed in a secondary operation by, for example, punching. Referring to FIG. 8, the slotted tube 12 may be formed by welding of an inner sheet 80 and an outer sheet 82 to a corrugated sheet 84 which forms dividers between adjacent coolant passages 86.

Landscapes

• 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)

Applications Claiming Priority (2)

Publications (1)

Family

ID=44630291

Family Applications (1)

Country Status (4)

Families Citing this family (11)

Family Cites Families (16)

• 2011
  • 2011-08-09 CN CN201180043570.3A patent/CN103238038B/zh not_active Expired - Fee Related
  • 2011-08-09 US US13/818,386 patent/US20130153174A1/en not_active Abandoned
  • 2011-08-09 EP EP11743942.2A patent/EP2609389A2/de not_active Withdrawn
  • 2011-08-09 WO PCT/US2011/047044 patent/WO2012027098A2/en active Application Filing

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events