WO2019118872A1 - Échangeurs de chaleur ayant des joints tubes-ailettes brasés et leurs procédés de production - Google Patents

Échangeurs de chaleur ayant des joints tubes-ailettes brasés et leurs procédés de production Download PDF

Info

Publication number
WO2019118872A1
WO2019118872A1 PCT/US2018/065743 US2018065743W WO2019118872A1 WO 2019118872 A1 WO2019118872 A1 WO 2019118872A1 US 2018065743 W US2018065743 W US 2018065743W WO 2019118872 A1 WO2019118872 A1 WO 2019118872A1
Authority
WO
WIPO (PCT)
Prior art keywords
tube
fins
slots
heat exchanger
circular
Prior art date
Application number
PCT/US2018/065743
Other languages
English (en)
Inventor
Yoram Shabtay
Daniel BACELLAR
Cara Martin
Dennis NASUTA
Reinhard Radermacher
John Black
Original Assignee
Heat Transfer Technologies Llc
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 Heat Transfer Technologies Llc filed Critical Heat Transfer Technologies Llc
Priority to US16/478,079 priority Critical patent/US20200318911A1/en
Publication of WO2019118872A1 publication Critical patent/WO2019118872A1/fr

Links

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
    • F28D1/047—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/0008—Soldering, e.g. brazing, or unsoldering specially adapted for particular articles or work
    • B23K1/0012—Brazing heat exchangers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/008—Soldering within a furnace
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/19—Soldering, e.g. brazing, or unsoldering taking account of the properties of the materials to be soldered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/20—Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
    • B23K1/203—Fluxing, i.e. applying flux onto surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • B23P15/26—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass heat exchangers or the like
    • 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
    • F28D1/0233—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 air flow channels
    • F28D1/024—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 air flow channels with an air driving element
    • 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
    • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/0233—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes the conduits having a particular shape, e.g. non-circular cross-section, annular
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/0246—Arrangements for connecting header boxes with flow lines
    • F28F9/0256—Arrangements for coupling connectors with flow lines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/04—Tubular or hollow articles
    • B23K2101/06—Tubes
    • B23K2101/08—Tubes finned or ribbed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/04—Tubular or hollow articles
    • B23K2101/14—Heat exchangers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/08—Non-ferrous metals or alloys
    • B23K2103/10—Aluminium or alloys thereof
    • 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
    • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/0283—Means for filling or sealing heat pipes
    • 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
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2225/00—Reinforcing means
    • F28F2225/04—Reinforcing means for 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
    • F28F2275/00—Fastening; Joining
    • F28F2275/04—Fastening; Joining by brazing
    • F28F2275/045—Fastening; Joining by brazing with particular processing steps, e.g. by allowing displacement of parts during brazing or by using a reservoir for storing brazing material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2275/00—Fastening; Joining
    • F28F2275/06—Fastening; Joining by welding

Definitions

  • the present invention generally relates to brazing and heat exchanger technologies.
  • the invention encompasses methods of producing heat exchangers by brazing serpentine round tubes to a plurality of fins.
  • the present invention provides heat exchangers and method of producing the same that include brazed tube-to-fin joints with a significantly reduced number of tube brazed joints, increased strength, and increased fin contact area relative to conventional heat exchangers with mechanical interference-fit tube-to-fin joints.
  • a heat exchanger includes fins having“dogbone”-shaped slots formed therethrough that each defines one or more circular portions interconnected with and intersected by a rectilinear portion that has a width that is narrower than a diameter of the circular portions.
  • Each circular portion has an incomplete circular perimeter and a collar bordering the incomplete circular perimeter.
  • At least one tube is provided having reverse bends forming at least two parallel tube runs to define a serpentine coil. The tube traverses back and forth through the slots formed in the fins.
  • the perimeters of the collars are metallurgically joined to corresponding portions of the tube with brazed joints, and the fins each comprise surface enhancements located between the slots thereof and located along the rectilinear portions thereof.
  • a method of producing a heat exchanger includes the steps of providing fins having“dogbone” -shaped slots formed therethrough such that each slot defines a one or more circular portions interconnected with and intersected by a rectilinear portion therebetween that has a width that is narrower than a diameter of the circular portions.
  • Each circular portion has an incomplete circular perimeter and a collar bordering the incomplete circular perimeter.
  • the fins each comprise surface enhancements located between the slots thereof and located along the rectilinear portions thereof.
  • the fins are assembled with at least one tube having reverse bends forming at least two parallel tube runs to define a serpentine coil such that the tube traverses back and forth through the slots formed in the fins, wherein either the fins or the tube is formed of a material clad with a braze material, and then performing a brazing operation on the fins and the tube such that the collars are metallurgically joined to corresponding portions of the tube with brazed joints formed by the braze material.
  • a heat exchanger as described above comprises a hole in at least a first of the reverse bends and a connection fluidically coupled to the hole is configured to either feed a fluid into or discharge the fluid from a pair of circuits of the tube coupled to opposite ends of the first reverse bend.
  • FIGS. 1 and 2 schematically represent nonlimiting first and second embodiments of heat exchangers comprising one or more serpentine tubes in accordance with certain aspects of the invention.
  • FIG. 3A schematically represents fluid flow in a prior art heat exchanger
  • FIG. 3B schematically represents fluid flow in a heat exchanger that utilizes a serpentine tube in accordance with a nonlimiting aspect of the invention
  • FIG. 3C represents a detailed view of an optional split adapter used in the construction of the heat exchanger configuration of FIG. 3B.
  • FIGS. 4A through 4D represent methods of producing holes in round bends of a serpentine tube in accordance with certain aspects of the invention.
  • FIG. 5A represents locations of multiple brazed joints in a prior art non- continuous“hairpin” tube type heat exchanger. Each hairpin has a mating return “U” bend resulting in two brazed connections for each hairpin.
  • FIG. 5B represents a heat exchanger that utilizes a continuous serpentine tube having brazed joints at only the inlet and outlet thereof in accordance with a nonlimiting aspect of the invention.
  • FIGS. 6A and 6B schematically represent serpentine tubes having different degrees of orientation in accordance with nonlimiting aspects of the invention.
  • FIG. 7 represents tube flow configurations for heat exchangers equipped with serpentine tubes in accordance with nonlimiting aspects of the invention.
  • FIG. 8 represents partial views of two fins having surface enhancements and different types of dogbone-type slots formed therein for receiving a serpentine tube in accordance with nonlimiting aspects of the invention.
  • FIG. 9 schematically represents plan and cross-sectional views of a portion of either fin of FIG. 8 and a collar formed on the fin to surround a circular portion of the slot in the fin.
  • FIGS. 10A and 10B represent methods of assembling serpentine tubes with fins having the types of slots represented in FIG. 8.
  • FIG. 11 shows images of brazed tube-to-fin joints of a serpentine heat exchanger produced using a brazing method in accordance with certain aspects of the invention.
  • FIG. 12 shows images of mechanical interference-fit tube-to-fin joints of a prior art non-brazed serpentine heat exchanger.
  • FIG. 13A represents partial plan and end views of a prior art fin configured for receiving an individual round tube of a prior art heat exchanger
  • FIGS. 13B and 13C represent partial plan and end views of two nonlimiting enhanced fins for receiving a portion of a serpentine tube in accordance with nonlimiting aspects of the invention.
  • FIG. 14 represents plan and end views of a fin with surface enhancements having a non-limiting circular portion with a 100-degree perimeter in accordance with another nonlimiting aspects of the invention.
  • FIG. 15 is a graph plotting simulation results of a continuous serpentine tube-type heat exchanger of the type represented in FIGS. 1 and 2, compared to a baseline air conditioning heat exchanger conventionally formed with hairpin-style tubes and fins with surface enhancements.
  • FIG. 5A schematically represents typical locations of multiple brazed joints in a noncontinuous serpentine tube 14A of a prior art non-continuous “hairpin” round tube-type heat exchanger.
  • the serpentine tube 14A comprises hairpins 46 and U-shaped tube sections (U-bends) 48.
  • Each hairpin tube 46 is inserted into a stack of fins (not shown) with round holes and collars.
  • the tubes 46 are then mechanically expanded to interface and contact the collars.
  • the U-bends 48 are brazed to ends of each hairpin tube 46 to form multiple brazed joints 47 as shown.
  • Each return U-bend 48 results in two brazed joints 47.
  • Fig 5B represents a single continuous serpentine tube 14B capable of use in heat exchangers in accordance with nonlimiting aspects of this invention.
  • the continuous serpentine tube 14B of FIG. 5B only requires brazed joints 17 at its inlet and outlet.
  • Various embodiments of the invention will be described below as incorporating a continuous serpentine tube of the type represented in FIG. 5B, in part because the ability to reduce the number of brazed joints 17 reduces the likelihood of refrigerant leaks.
  • FIGS. 1 and 2 schematically represent nonlimiting examples of heat exchangers 10A and 10B that utilize aspects of the continuous serpentine tube 14B of FIG. 5B.
  • Each heat exchanger 10A and 10B comprises one or more round continuous serpentine tubes 14, each having multiple reverse (180 degree or U- shaped) bends (elbows) 16 and parallel straight tube runs 18.
  • multiple continuous serpentine tubes 14 are used to define multiple discrete fluid circuits of the heat exchanger 10A, and the tubes 14 are connected to define what may be referred to as a serpentine coil.
  • FIG. 1 schematically represent nonlimiting examples of heat exchangers 10A and 10B that utilize aspects of the continuous serpentine tube 14B of FIG. 5B.
  • Each heat exchanger 10A and 10B comprises one or more round continuous serpentine tubes 14, each having multiple reverse (180 degree or U- shaped) bends (elbows) 16 and parallel straight tube runs 18.
  • multiple continuous serpentine tubes 14 are used to define multiple discrete fluid circuits of the heat exchanger 10A, and the tubes 14 are connected
  • a reduced number of brazed joints is achieved with a single continuous serpentine tube 14 that defines a serpentine coil and multiple discrete fluid circuits of the heat exchanger 10B.
  • the multiple discrete fluid circuits of the heat exchangers 10A and 10B offer the advantages of additional circuitry connections and reduced pressure drop as compared to a long continuous serpentine tube of the type represented in FIG. 5B.
  • the tubes 14 traverse back and forth through series of slots (not shown) formed in a plurality of parallel fins 12, and each fin 12 is metallurgically joined with a brazing material to corresponding tube runs 18 of the tubes 14 to define brazed joints at the slots of the fin 12.
  • the heat exchangers 10A and 10B are configured to transfer heat between a fluid (hereinafter referred to as a liquid as a matter of convenience) flowing through their respective coils with another fluid (hereinafter referred to as a gas as a matter of convenience) flowing through the stack of fins 12 (for example, in a direction perpendicular to the plane of the images of FIGS. 1 and 2) for the purpose of heating or cooling the liquid and/or gas.
  • a fluid hereinafter referred to as a liquid as a matter of convenience
  • a gas as a matter of convenience
  • the flow directions of a liquid through the tubes 14 are represented with arrows in FIGS. 1 and 2.
  • the continuous serpentine tube-type heat exchangers 10A and 10B of FIGS. 1 and 2 may be assembled by inserting a complete serpentine tube 14 into a stack of fins 12 each having elongated’’dogbone” shaped slots (i.e. , slots having a pair of generally circular portions and a rectilinear portion therebetween that is narrower than the circular portions).
  • the leading edge of the serpentine tube 14 is narrowed (e.g., flattened slightly) to allow the serpentine tube 14 to be inserted through the slots in the fins 12.
  • the fins 12 of the continuous serpentine tube-type heat exchangers 10A and 10B are also formed to have surface enhancements at locations along and between their dogbone slots to promote the heat transfer efficiency of the heat exchangers 10A and 10B.
  • the heat exchangers 10A and 10B comprise certain features and aspects that are believed to provide comparable or improved performance relative to conventional heat exchangers that have serpentine round tubes and non-enhanced fins, or have hairpin-tubes with enhanced fins that are joined mechanically to yield what are referred to herein as mechanical interference-fit tube-to-fin joints, or more simply mechanical joints.
  • Exemplary improvements are represented in FIG. 15, which shows simulation results of a continuous serpentine tube-type heat exchanger of the type described above in reference to FIGS. 1 and 2, compared to a baseline air conditioning heat exchanger conventionally formed with hairpin-style tubes and fins with surface enhancements.
  • the heat exchangers 10A and 10B may provide improvements for a wide variety of applications including air conditioning, refrigeration, heat pumps, and other devices that use a heat exchanger to transfer heat between a gas and a liquid.
  • FIG. 1 represents an example of a joining configuration for serpentine tube heat exchangers where parallel circuitry is desired in order to reduce liquid pressure drop, wherein each tube 14 of the serpentine coil individually has a connection for receiving the liquid and a connection for discharging the liquid from the discrete fluid circuit defined by the tube 14.
  • the heat exchanger of FIG. 2 represents an example of advantageously reducing the number of brazed joints as compared to the heat exchanger 10A of FIG. 1 by using a split joining configuration wherein multiple circuits (in FIG. 2, pairs of adjacent circuits) receive the liquid through a shared split connection 19A and multiple circuits (in FIG. 2, one pair of adjacent circuits) discharge the liquid through a shared split connection 19B, thus resulting in fewer overall feeding/discharging connections required.
  • the split joining configuration of FIG. 2 provides for a significant reduction in joints per circuit and a potential reduction in refrigerant pressure drop and further reduced risk of refrigerant leakage.
  • FIG. 3A schematically represents a row of prior art hairpins 46 prior to their assembly and brazing to return“U-bends” to yield a discontinuous serpentine tube with multiple braze joints.
  • FIGS. 3B and 3C schematically represent a continuous serpentine tube 40 with adjacent bends, one of which is equipped with a straight tube section 42 forming a split joining configuration that can function as an inlet or outlet (indicated as an outlet in FIG. 3B).
  • FIG. 3C schematically represents an isolated view of a bend of the serpentine tube 40 that was produced to include the straight tube section 42 during investigations leading to the present invention.
  • a hole was formed in the bend via electrical discharge machining (EDM) and then expanded to form a collar (not shown) to accept the tube section 42.
  • EDM electrical discharge machining
  • the tube section 42 was then partially inserted into the hole so that the collar firmly held the tube section 42 in place prior to brazing.
  • the technique can also be used to form the split connections of a continuous serpentine tube similar to that of FIG. 2. That is, EDM may be used to provide a hole directly in one or more of the bends 16 of the continuous serpentine coil, and the holes may undergo additional forming to produce collars into which straight tube sections 42 may be inserted. The straight tube sections 42 and bends 16 are then metallurgically joined with brazed joints formed during a subsequent brazing process.
  • FIGS. 4A through 4D represent four methods of providing holes in a bend of a serpentine tube (such as the U-shaped bends 16 of the tube 14 in FIG. 2).
  • FIG. 4A depicts a first method in which partial holes are cut in edges of a sheet before rolling the sheet into a tube, which can then undergo bending to form a U-shaped bend.
  • FIG. 4A depicts a first method in which partial holes are cut in edges of a sheet before rolling the sheet into a tube, which can then undergo bending to form a U-shaped bend.
  • FIG. 4B depicts a second method in which a hole is punched in a tube after the tube has been bent to form a U-shaped bend.
  • the bend is punctured to form the hole after the tube has been brazed to fins to avoid hole tapping with any cladding material on surfaces of the tube 14.
  • a particular challenge for this method is having a tool that fits within the confined space between the inside of the bend and the fins.
  • FIG. 4C depicts a third method in which a round hole is punched in a straight round tube before the tube is bent to form a U-shaped bend. Puncturing the tube is relatively easy, but the round hole becomes elliptical once the tube is bent to form the bend. Additionally, hole locations need to be precisely calculated to match the coil design.
  • FIG. 4D depicts a fourth method in which an elliptical hole is punched in a straight round tube before the tube is bent to form a U-shaped bend, and the hole acquires a rounder shape when the tube is bent to form
  • serpentine tubes 14 (FIGS. 1 and 2), 40 (FIGS. 3B and 3C), and 14B (FIG. 5B) define serpentine coils that essentially entirely lie in a single plane, such that adjacent bends 16 of the coil are oriented at an angle Q of 0 degrees, as represented by the tube 14 in FIG. 6B.
  • adjacent bends 16 of the serpentine coil may be oriented at a corrugation angle Q other than 0 degrees (slanted) such that the coil "zigzags" back and forth between what can be described as separate banks of tubes that lie in separate but parallel planes, as represented by the tube 14 in FIG. 6A.
  • the heat exchangers 10A and 10B may include one or more banks of tubes.
  • either or both coil configurations of FIGS. 6A and 6B may be used.
  • the coil configuration of FIG. 6B can be utilized in full-cross counter flow heat exchangers, while the coil configuration of FIG. 6A can be utilized in semi-cross parallel or counter flow heat exchangers.
  • FIG. 8 represents two nonlimiting types of slots (Type 1 and Type 2) that may be formed in the fins 12 of the heat exchangers 10A and 10B to receive their serpentine tubes 14.
  • the fin 12 identified as Type 1 has a“dogbone” slot 22 aligned parallel to the longitudinal length of the fin 12 and defined by a pair of generally circular portions 24 intersected and interconnected by an intermediate rectilinear portion 26 therebetween that is narrower than the circular portions 24.
  • the fin 12 identified as Type 2 has partial “dogbone” slots 23 each aligned perpendicular to the longitudinal length of the fin 12 and defined by a single circular portion 24 intersected by a rectilinear portion 27 that is narrower than the circular portion 24 and defines an opening at a downstream edge of the fin 12.
  • the circular portions 24 of the slots 22 and 23 do not have complete circular perimeters, but instead each circular portion 24 has an incomplete circular perimeter that spans an arc of greater than 180 degrees.
  • the circular sections 24 are not required to form mechanical interference-fit joints with the tubes 14 with which they are assembled.
  • the circular portions 24 of the slots 22 and 23 can be sized to define a radial gap 33 between the tube 14 and fin 12 of greater than 0 mm up to about 0.1 mm, for example, from about 0.05 to 0.1 mm, which must be bridged by a brazed joint.
  • a Type 2 fin slot 23 may be complete and similar to a Type 1 slot 22.
  • the Type 2 fin is similar to Type 1 except that the slot orientation is perpendicular to the Type 1 slot.
  • a collar 32 borders at least a portion of, and preferably the entire, incomplete circular perimeter of each circular portion 24 of the slots 22 and 23, so that an inner surface of the collar 32, and not just the inner edge of the circular portion 24, faces the outer circumference of the tube 14 and is available as a heat transfer path between the tube 14 and fin 12.
  • the collars 32 can be formed by material of the fin 12 that has been bent away from adjoining surfaces of the fin 12. As represented in FIG.
  • the collars 32 may be preferably formed to have a reflare section 34, defined herein as a surface that bends away from the central axis of the collar 32 and the circular portion 24 it borders.
  • the reflare sections 34 of the collars 32 allow the fins 12 to be stacked one against the other without the fins 12 telescoping into each other, which allows for the assembly of heat exchangers 10A and 10B with increased fin densities relative to, for example, conventional refrigerator low-fin density evaporators using serpentine tube designs.
  • FIG. 10A schematically represents the manner in which a serpentine tube 14 can be inserted into a stack of the Type 1 fins 12 of FIG. 8 in the transverse (z-axis) direction of the fins 12.
  • This insertion method is essentially the same as would be employed to assemble a serpentine tube with a stack of conventional fins.
  • the interference fit required to create the mechanical joints between a tube and conventional fins requires a relatively high force to insert the tube through a stack of fins. This necessitates the use of fins that are stiff, which discourages the presence of surface enhancements on the fins.
  • the gap 33 between the fins 12 and tube 14 of this invention reduce the force required to insert the tube 14 into a stack of the Type 1 fins 12 of FIG. 8.
  • the fins 12 can be equipped with surface enhancements 36 capable of significantly increasing the thermal efficiency of the fins 12. Investigations leading up to the present invention showed that gap 33 between the fins 12 and a tube 14 of up to about 0.1 mm can be easily bridged by a braze material.
  • FIG. 10B represents two methods of inserting serpentine tubes 14 into a Type 2 fin 12 of FIG. 8.
  • One method involves lateral insertion of the tube 14 in the x-axis direction of each fin 12, and the other method involves bending the series of the bends 12 on one end of the tube 14 so that it can move through the slots 23 in the transverse (z-axis) direction of each fin 12.
  • solid white arrows indicate the directions of tube insertion.
  • the serpentine tube lead area is slightly flattened to allow the tube 14 to penetrate the“dogbone” shape slot 23.
  • the tube leading bends in FIG. 10A are slightly flattened to allow penetration of the serpentine tube 14 through the rectilinear portion 27 of the slot 23.
  • the entire heat exchanger assembly may be de-greased to remove process oils if needed. Then the entire heat exchanger is placed in a furnace and heated at appropriate temperatures and durations to form complete brazed joints between the tubes 14 and fins 12.
  • the components of the heat exchangers 10A and 10B may be formed of various materials suitable for brazing and producing brazed joints between the tubes 14 and fins 12.
  • either the tubes 14 or fins 12 may be formed of a material having a cladding material thereon that contains a source of the braze material.
  • the tubes 14 may be formed of an aluminum alloy having a clad layer formed of a 4000-series aluminum-silicon alloy as the braze material. Such alloys typically contain about 10 to 12% silicon and the clad layer thickness accounts for about 10% of the wall thickness of the tube 14.
  • Fluxing of the heat exchanger assembly prior to brazing can be performed using various methods capable of depositing a small controlled amount of flux on the components of the assembly. For example, one such method involves mixing a flux powder with isopropyl alcohol and spraying the resulting flux mixture on the assembly while the flux powder is kept in suspension. Another such method involves pouring a mixture of a flux powder and water on the assembly. After the flux mixtures are applied, the heat exchanger assembly is preferably dried, for example, using forced hot air or in a drying furnace.
  • the brazing operation is performed in a furnace that contains an inert atmosphere, for example, nitrogen gas, to reduce the likelihood of oxidation of the alloy from which the tubes 14 are made.
  • a controlled atmosphere brazing furnace (CAB) is particularly well suited for this purpose, though other aluminum brazing equipment and methods may be used.
  • the temperature profile of the brazing operation may include a rapid temperature increase up to the point where the flux melts.
  • the flux removes any oxide layer from the surfaces of the heat exchanger components and allows the cladding material, as the source of the braze material, to properly flow and wet the surfaces to be joined by the braze material.
  • the temperature of the assembly preferably continues to increase to the liquidus temperature of the braze material.
  • Tube-to-fin joints are created as the braze material flows to create the required braze joint fillets.
  • the creation of the fillets is also aided by capillary action of the gap 33 between the tube 14 and fins 12, which is preferably not greater than about 0.1 mm to reduce the risk of forming incomplete fillets if there is insufficient braze material.
  • the assembly is held at the liquidus temperature of the braze material for a duration dependent on a few factors. For example, the size of the heat exchanger assembly and how homogeneous the temperature distribution is within the furnace. Afterwards, the resulting brazed heat exchanger is moved from the brazing chamber to a cooling zone of the furnace where the brazed heat exchanger is cooled before exiting the furnace. If removal of the dried flux residue is desired, the heat exchanger can be washed.
  • sample heat exchanger assemblies were produced using aluminum alloy (Alloy 3003) tubes having 7.2 or 8 mm outer diameters and 0.6 mm wall thicknesses, and an outer clad layer containing an aluminum-silicon eutectic brazing alloy (Alloy 4045) and 1 % zinc.
  • the clad layer constituted about 10% of the wall thickness.
  • the tubes were assembled with fins resembling the Type 1 fin represented in FIG. 8 as having a“dogbone” slot and circular portions bordered by collars with a reflare section, as described above in reference to FIG. 9.
  • the reflare sections of the collars were intentionally formed to promote stacking of the fins without the fins telescoping into each other and to allow for the building of heat exchangers 10A and 10B with increased fin densities and homogeneous fin spacing relative to, for example, conventional low-density, no enhancement fin refrigerator evaporators using serpentine tube designs.
  • the sizes of the slots and collars of the fins were such that radial gaps of up to 0.1 mm were present between the fins and the tubes assembled therewith.
  • the samples were coated with a standard aluminum brazing flux. It was observed that even when the fins were stacked closely such that their collars contacted adjacent fins, the flux was able to penetrate and coat surfaces of the tubes and fins within the areas of contact between the tubes and the fin collars. In particular, the flux appeared to penetrate and coat the required area of the collar and tube through the remaining open area within each slot.
  • the samples were brazed in a nitrogen atmosphere furnace following a temperature profile of a temperature rise up to 605°C, a soak time of about one minute, and cooling to about 150°C, after which the samples were removed from the furnace and air cooled to room temperature.
  • brazed joints were achieved with complete fillets inside and around each fin collar, filling the gaps between the collars and tubes. Therefore, it was concluded that the reflare sections of the collars were beneficial to stacking the fins to increase fin densities without the fins telescoping into each other and that flux could penetrate to the required areas to provide a good braze joint.
  • FIG. 1 1 shows images of brazed joints of a serpentine heat exchanger produced during the investigation.
  • FIG. 12 shows images of mechanical joints of a conventional non-brazed serpentine heat exchanger. Without brazed joints, there are gaps between the tube and fins in FIG. 12, and the gaps can be larger than the fin thickness. In contrast, the brazed joints completely fill the gaps between the tube and fins in FIG. 1 1 . Even where the gap between a fin and the tube was large, the braze material was able to completely bridge the gap.
  • the brazed joint established a much wider contact area that extended from beyond the tip of the "pseudo-collar” to the tip of the braze material between the tube and the "elbow” of the "pseudo-collar.”
  • This wider contact area between the fins and tubes improves the heat transfer and therefore increases the performance of the heat exchanger.
  • This increased contact surface area compensates for the lack of fin surface area due to the large dogbone slot 22, compared with a conventional fin having a circular hole (FIG 13A).
  • brazed heat exchangers 10A and 10B may include smooth planar fins 12 of the types used on conventional heat exchangers, they may also or alternatively include fins 12 having surface enhancements that significantly increase fin efficiency. Such enhancements have been determined to allow fins 12 having dogbone-shaped slots 22 or 23 to perform competitively with conventional fins having circular interference-fit holes despite a reduced surface area due to the presence of the rectilinear portion 26 or 27 of the slot 22 or 23.
  • FIG. 13A represents a fragment of a fin 12A of a type used in conventional mechanically-expanded tube heat exchangers used in air- conditioners, having multiple hair-pin tubes, multiple brazed 'll” bends, and fully circular (360 degree) holes 20 with louvers 28 between each hole 20 that serve as surface enhancements.
  • FIGS. 13B and 13C represent two nonlimiting embodiments by which surface enhancements can be incorporated into brazed serpentine tube heat exchangers of the type disclosed above (e.g., FIGS. 1 and 2) to improve the performance of the heat exchangers such that they perform equal to or better than conventional air-conditioner heat exchangers.
  • FIGS. 13B and 13C represent fragments of fins 12B and 12C having“dogbone” shaped slots 22 and rectilinear portions 26 that subtend an angle of about 120 degrees of their respective circular portions 24.
  • FIG. 13B represents the fin 12B as having eight louvers 28 between the slots 22 and twelve winglets 30 adjacent to the slot 22.
  • FIG. 13C represents the fin 12C as having twelve upper louvers 28A between the slots 22 and eight lower louvers 28B adjacent to the slots 22.
  • the upper and lower louvers 28A and 28B do not necessarily have the same dimensions and characteristics.
  • the end views of each fin 12A, 12B, and 12C show relative angles of the louvers 28. Fins 12 having other enhancement configurations are foreseeable and within the scope of the invention.
  • FIG. 14 represents a modified version of the fin 12C of FIG. 13C, labeled in FIG. 14 as 12D, wherein the rectilinear portions 26 are narrowed such that they subtend an angle of about 100 degrees of their respective circular portions 24.
  • This modification increases the tube-to-fin contact area at the collar (not shown).
  • the lower louvers 28B also include larger dimensions since there is additional space available.
  • narrowing the rectilinear portion 26 requires the tube 14 to be further flattened in order to be inserted into the slot 22. As the tube 14 flattens, its cross-sectional area reduces, thus increasing a local flow resistance and resulting in a pressure drop penalty.
  • Brazing serpentine tube-to-fin joints as described herein provides significantly increased joint strength compared to mechanical joints. This improved strength allows for the production of larger heat exchangers, particularly for air-conditioning and large refrigeration systems which were previously limited in size due to mechanical joints in the prior art heat exchanger.
  • the brazed joints also provide increased surface contact area and therefore increased thermal conductivity between tube and fin thus improving heat exchanger performance. Brazed joints also allow for the introduction of surface enhancements like louvers on the fin surface since little pressure is exerted on the fins during insertion into the serpentine tube.
  • the heat exchanger 10 and its components could differ in appearance and construction from the embodiment described herein and shown in the drawing, functions of certain components of the heat exchanger 10 could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function, various materials could be used in the fabrication of the heat exchanger 10 and/or its components, and the heat exchanger 10 could be installed in various types of heating, cooling, or electrical systems.
  • the invention encompasses additional or alternative embodiments in which one or more features or aspects of a particular embodiment could be eliminated.

Abstract

L'invention concerne des échangeurs de chaleur et des procédés de production de ceux-ci, lesquels échangeurs ont des ailettes avec des fentes formées à travers celles-ci, et un tube continu ayant des passages de tube parallèles reliés par des coudes inverses de façon à définir un enroulement en serpentin qui traverse en aller et retour les fentes formées dans les ailettes. Chaque ailette a des améliorations de surface et est reliée de façon métallurgique à des parties correspondantes du tube au niveau des fentes avec des joints brasés entre celles-ci.
PCT/US2018/065743 2017-12-15 2018-12-14 Échangeurs de chaleur ayant des joints tubes-ailettes brasés et leurs procédés de production WO2019118872A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US16/478,079 US20200318911A1 (en) 2017-12-15 2018-12-14 Heat exchangers having brazed tube-to-fin joints and methods of producing the same

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201762599047P 2017-12-15 2017-12-15
US62/599,047 2017-12-15

Publications (1)

Publication Number Publication Date
WO2019118872A1 true WO2019118872A1 (fr) 2019-06-20

Family

ID=66820670

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2018/065743 WO2019118872A1 (fr) 2017-12-15 2018-12-14 Échangeurs de chaleur ayant des joints tubes-ailettes brasés et leurs procédés de production

Country Status (2)

Country Link
US (1) US20200318911A1 (fr)
WO (1) WO2019118872A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021046314A1 (fr) * 2019-09-05 2021-03-11 Carrier Corporation Échangeur de chaleur à vortex amélioré

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11774187B2 (en) * 2018-04-19 2023-10-03 Kyungdong Navien Co., Ltd. Heat transfer fin of fin-tube type heat exchanger
KR20200078936A (ko) * 2018-12-24 2020-07-02 삼성전자주식회사 열 교환기
US11359836B2 (en) * 2020-08-04 2022-06-14 Rheem Manufacturing Company Heat exchangers providing low pressure drop

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5509469A (en) * 1994-04-19 1996-04-23 Inter-City Products Corporation (Usa) Interrupted fin for heat exchanger
US5535820A (en) * 1995-07-18 1996-07-16 Blissfield Manufacturing Company Method for assembling a heat exchanger
US20030196784A1 (en) * 2002-03-07 2003-10-23 Utter Robert E. Plate-fin and tube heat exchanger with a dog-bone and serpentine tube insertion
EP1528346A2 (fr) * 2003-10-30 2005-05-04 Brazeway, Inc. ailette et échangeur de chaleur
KR20100108754A (ko) * 2009-03-30 2010-10-08 주식회사 한국번디 턴핀형 열교환기, 이를 이용한 열교환 시스템 및 턴핀형 열교환기의 제조방법
KR101782646B1 (ko) * 2011-01-12 2017-09-28 엘지전자 주식회사 공기 조화기

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5509469A (en) * 1994-04-19 1996-04-23 Inter-City Products Corporation (Usa) Interrupted fin for heat exchanger
US5535820A (en) * 1995-07-18 1996-07-16 Blissfield Manufacturing Company Method for assembling a heat exchanger
US20030196784A1 (en) * 2002-03-07 2003-10-23 Utter Robert E. Plate-fin and tube heat exchanger with a dog-bone and serpentine tube insertion
EP1528346A2 (fr) * 2003-10-30 2005-05-04 Brazeway, Inc. ailette et échangeur de chaleur
KR20100108754A (ko) * 2009-03-30 2010-10-08 주식회사 한국번디 턴핀형 열교환기, 이를 이용한 열교환 시스템 및 턴핀형 열교환기의 제조방법
KR101782646B1 (ko) * 2011-01-12 2017-09-28 엘지전자 주식회사 공기 조화기

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021046314A1 (fr) * 2019-09-05 2021-03-11 Carrier Corporation Échangeur de chaleur à vortex amélioré
US11519679B2 (en) 2019-09-05 2022-12-06 Carrier Corporation Vortex-enhanced heat exchanger

Also Published As

Publication number Publication date
US20200318911A1 (en) 2020-10-08

Similar Documents

Publication Publication Date Title
US20200318911A1 (en) Heat exchangers having brazed tube-to-fin joints and methods of producing the same
US9322602B2 (en) Heat exchanger having a plurality of plate-like fins and a plurality of flat-shaped heat transfer pipes orthogonal to the plate-like fins
KR100365639B1 (ko) 열교환기
EP1714100B1 (fr) Méthode de production d'un échangeur thermique à ailettes en plaques brasées
EP2929269B1 (fr) Échangeur thermique et son procédé de fabrication
US20100314092A1 (en) Heat transfer tube
EP2863159B1 (fr) Echangeur de chaleur, méthode de production de celui-ci et dispositif à cycle de réfrigération
EP2738506A2 (fr) Échangeur de chaleur et son procédé de fabrication
CN106482568B (zh) 用于换热器的换热管、换热器及其装配方法
JP2004020174A (ja) 平板形放熱フィン、それを用いた熱交換器及びその製造方法
JP4080352B2 (ja) フィンチューブ型熱交換器の製造方法及び空調冷凍装置
JP2012247091A (ja) フィン・アンド・チューブ型熱交換器
US20060169019A1 (en) Tabbed transfer fins for air-cooled heat exchanger
EP3845851B1 (fr) Échangeur de chaleur, unité d'échangeur de chaleur et dispositif à cycle de réfrigération
EP3578913B1 (fr) Échangeur de chaleur et appareil à cycle frigorifique
JP2012172892A (ja) フィン・アンド・チューブ型熱交換器
JPH03128167A (ja) 熱交換器の製造方法
JP2011257084A (ja) オールアルミニウム熱交換器
JP6674262B2 (ja) 熱交換器及びその製造方法
EP1179719A2 (fr) Procédé de fabrication d'un tube d'échangeur de chaleur
JP2004279025A (ja) クロスフィンチューブ式熱交換器
JP2012202572A (ja) フィン・アンド・チューブ型熱交換器
KR19990021468A (ko) 핀형 응축기 및 핀형 응축기용 파이프의 밴딩방법
JP2001091179A (ja) プレートフィンチューブ型熱交換器およびその製造方法とそれを用いた冷蔵庫
EP2405224A1 (fr) Procédé de fabrication d'un échangeur de chaleur

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18888972

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18888972

Country of ref document: EP

Kind code of ref document: A1