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
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D7/00—Bending rods, profiles, or tubes
  • B21D7/02—Bending rods, profiles, or tubes over a stationary forming member; by use of a swinging forming member or abutment
  • B21D7/024—Bending rods, profiles, or tubes over a stationary forming member; by use of a swinging forming member or abutment by a swinging forming member
• • 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
  • F28D1/0478—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 the conduits having a non-circular cross-section
• • 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
  • F28F1/006—Tubular elements; Assemblies of tubular elements with variable shape, e.g. with modified tube ends, with different geometrical 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
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/02—Tubular elements of cross-section which is non-circular
  • F28F1/025—Tubular elements of cross-section which is non-circular with variable shape, e.g. with modified tube ends, with different geometrical features
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4935—Heat exchanger or boiler making
  • Y10T29/49391—Tube making or reforming

Definitions

• the present invention relates to a U-shaped heat exchanger tube. More particularly, the present invention is directed to a U-shaped heat exchanger tube with a concavity formed into a return bend of the U-shaped heat exchanger tube.
• straight tubes are bent in an approximate range of bend angles of 170° and 190° so as to form a unitary construction of two straight tube sections integrally connected with a return bend formed at a selected bend angle.
• a skilled artisan would appreciate that if the straight tube is bent precisely 180°, the two straight tube sections would extend parallel to one another while if the straight tube is bent at a selected bend angle anywhere in the approximate range other than 180°, the straight tube sections would extend generally parallel with one another.
• the term "generally parallel” shall refer to the relationship of the two straight tube sections after the straight tube is bent at any selected angle in the approximate range of 170° and 190° including the precise bend angle of 180°.
• Figures 2-6 illustrate sequential steps in the process of forming a tubular heat exchanger from straight stainless steel or aluminized steel tube.
• Figure 2 shows a tube bend tooling 6 that includes a bend die 8, clamp die 10, a pressure die 12, a plastic plug mandrel 14 and a plastic follower 16.
• the bend die 8 is a split die having symmetrical upper and lower sections 8a and 8b which, as shown in Figure 6, can be vertically separated at a midportion. When sections 8a and 8b are fitted together, these sections form a generally circular or cylindrical block having a horizontal tube groove 18 that has a generally elliptical curvature and is adapted for receiving a tube 20 or pipe.
• the tube groove 18 has a plurality of vertical elongated controlled-wrinkle serrations 22 that are disposed in an arc greater than 180 degrees. That is, the serrations 22 extend beyond the tangents of the bend portion of bend die 8.
• the centerline radius of the bend die is here approximately 2.5 inches. That is, the distance from the rotational axis of bend die 8 to the entrance of tube groove 18 is such that tube bent with the bend die 8 has a centerline radius of approximately 2.5 inches.
• Grip section 24 has a grip section tube groove 26 conforming to tube groove 18 except that it is linear and extends tangentially from tube groove 18.
• the bend die 8 is mounted to a rotary drive 28 such that the bend die 8 can be rotated during bending.
• the pressure die 12 and the clamp die 10 have respective linear tube grooves 30 and 32 that may preferably be elliptically shaped and adapted for receiving the tube 20. Initially, the pressure die 12 and the clamp die 10 are aligned side-by-side with tube grooves 30 and 32 linearly aligned and are spaced from an axis defined by tube groove 18 and the grip section 24.
• the plastic follower 16 having an arcuate surface generally conforming to the outer diameter of the tube 20 being bent is mounted behind the bend die 8 opposite the pressure die 12.
• a mandrel rod 34 with the plastic plug mandrel 14 on the end extends forwardly with the bend die 8 and the plastic follower 16 on one side and the pressure die 12 and the clamp die 10 on the opposite side.
• the drive mechanisms for the bend die 8, the pressure die 12, the clamp die 10, the mandrel rod 34, and the plastic follower 16 are not described in detail because they are conventional and an explanation of them is not necessary for understanding the invention.
• the tube 20 is positioned on the mandrel rod 34 and is held in place by a collet 36.
• the pressure die 12 and the clamp die 10 are then moved laterally so as to engage the tube 20. More specifically, the clamp die 10 is moved diametrically to the grip section 24 such that the face edges 38 of clamp die 10 respectively seat in conforming grip section notches 40 that are adjacent the grip section tube groove 26. Accordingly, the clamp die 10 and the grip section 24 are interlocked and the tube 20 is firmly clamped therebetween.
• a portion of the tube 20 immediately behind the clamp die 10 is received in the linear tube groove 30 of the pressure die 12. Lateral pressure exerted on the tube 20 by the pressure die 12 is restrained by the plastic follower 16. Also, a portion of face edges 38 (see Figure 4) of the pressure die 12 seat in and interlock with conforming notches 42 of the bend die 8.
• the bend die 8 and the clamp die 10 are rotated in unison while the pressure die 12 drives linearly forward with portions of face edges 44 continuously being seated in the conforming notches 42.
• the tube 20, which remains held by the collet 36, is driven forwardly to the bend point of the bend die 8.
• the plastic follower 16 has a relatively low coefficient of friction such that the tube 20 readily slides over it while the plastic follower 16 continues to restrain the pressure of the pressure die 12.
• the tube 20 continues to be clamped between the clamp die 10 and the grip section 24 as the clamp die 10 is driven by a suitable rotating arm 46.
• the tube 20 As the tube 20 bends around the rotating bend die 8, the inside of the tube bend is compressed and the metal flows into the elongated vertical serrations 22 thereby forming controlled wrinkles 48.
• the tube 20 is shown after it has been bent a full 180 degrees such that segments 20a and 20b are parallel.
• the bend die 8 has rotated 180 degrees from its initial orientation and likewise the clamp die 10 has been rotated 180 degrees about the central axis of the bend die 8 such that the linear tube groove 32 now faces in the opposite direction from its initial position and still clamps the tube 20 to the grip section 24 of the bend die 8.
• the pressure die 12 is shown to have linearly traversed to its forwardmost position where it still engages the tube 20 at its tangency point to the bend die 8.
• the plastic plug mandrel 14 remains in a stationary position within the tube 20 and thereby functions to limit the collapse of the pipe 20. More specifically, the plastic plug mandrel 14 does not advance around the bend as a multi-ball mandrel would but rather remains stationary with its tip being in an approximate region of the bend point.
• the plastic plug mandrel 14 is subject to wear that particularly occurs on the outside as the wall of the pipe 20 slides against it but the plastic plug mandrels 14 are relatively inexpensive to replace.
• tubes 20 may be bent without using a plastic plug mandrel or any other internal supporting structure.
• the tubes 20 can be bent as shown in Figures 2-6 without any collapse suppressing structure on the inside.
• the pressure die 12 and the clamp die 10 are moved in respective directions away from bend die 8 so as to release the tube 20.
• the upper section 8a of the bend die 8 is separated from the lower section 8b using a suitable apparatus so that the tube 20 can be removed from the bend die 8. More specifically, the flow of metal from the inside bends of the tube 20 into serrations 22 prevents the removal of the tube 20 from the bend die 8 without first splitting the bend die 8 and raising the tube 20 so that the tube 20 can be advanced forward for the next sequential rotation and bend.
• the tube 20 could not be removed horizontally from bend die 8 because the wrinkles 48 near the bend extremities engaged the corresponding serrations 22.
• the upper section 8a of the bend die 8 may be raised approximately 3/4 inches and then the tube 20 raised 3/8 inches to free it.
• the upper section 8a of the bend die 8 is re-engaged to the lower section 8b and the bend die 8 is rotated clockwise as shown back to the original orientation as shown in Figure 2.
• the clamp die 10 is rotated back adjacent the pressure die 12 and both are moved rearwardly to the starting position as shown in Figure 2.
• the tube 20 is moved forwardly to a new bend position and preferably rotated on its axis so that subsequent parallel segments are not linearly disposed with segments 20a and 20b. That is, the tube 20 may rotated in opposite directions from bend-to-bend so that the serpentine segments are vertically staggered so as to provide a desirable low profile arrangement for a tubular heat exchanger.
• Figure 1 shows a sectioned view of tube 20 after being bent in accordance with the conventional bending method with the bend of the tube having controlled wrinkles 48. As shown, there are controlled wrinkles 48 on the inside of the bend and some of the wrinkles 48 extend beyond a 180 degree arc. That is, the wrinkles 48 extend beyond the tangent points that provide the bend arc which makes segments 20a and b parallel with each other.
• An object of the present invention is to provide a heat exchanger tube having a U-shaped tube section defining a return bend and a pair of straight tube sections with the U-shaped tube section having a concavity formed thereinto.
• Yet another object to the invention is to provide a heat exchanger tube with a tight return bend with a concavity formed into the tight return bend that results in a reduced pressure loss of the heat exchange fluid as the heat exchange fluid flows therethrough.
• a heat exchanger tube includes a tube body that forms a hollow passageway and has a U- shaped tube section defining a return bend and a pair of straight tube sections.
• Respective ones of the straight tube sections are connected to the U-shaped section at respective connection locations and extend generally parallel to one another to define an internal space disposed between and among the U-shaped tube section and the straight tube sections connected to the U-shaped tube section.
• the U- shaped tube section has a concavity formed thereinto with the concavity defining a portion of the internal space.
• a heat exchanger serpentine tube includes a plurality of straight tube sections and a plurality of U-shaped tube sections.
• the plurality of straight tube sections are arranged in a plurality of generally parallel rows and disposed in a common plane.
• the plurality of U-shaped tube sections are connected to the plurality of straight tube sections in a manner such that a respective one of the U-shaped tube sections defining a return bend connects sequential ones of the plurality of straight tube sections to form a serpentine configuration.
• Sequential ones of straight tube sections connected to a respective one of the U-shaped sections define an internal space disposed between and among the respective U-shaped tube section and the sequential ones of the straight tube sections.
• Each one of the U-shaped tube sections has a concavity formed thereinto with the concavity defining a portion of the internal space.
• Another exemplary embodiment of the present invention is a heat exchanger that includes an inlet header, an inlet connection connected to the inlet header, an outlet header, an outlet connection connected to the outlet header and a plurality of heat exchanger serpentine tube bodies.
• the plurality of serpentine tube bodies interconnects the inlet and outlet headers.
• Figure 1 is a partial cross-sectional view of a prior art heat exchanger tube having a bend with wrinkles of formed therein.
• Figure 2 is a perspective view of prior art tube bending tooling prior to receiving a heat exchanger tube to be bent.
• Figure 3 is a perspective view of the prior art tube bending tooling with the heat exchanger tube being clamped in the prior art tube bending tooling before bending.
• Figure 4 is a perspective view of the prior art tube bending tooling with the heat exchanger tube bent at approximately 90°.
• Figure 5 is a perspective view of the prior art tube bending tooling with the heat exchanger tube bent at approximately 180°.
• Figure 6 is a perspective view of the prior art tube bending tooling with the heat exchanger tube bent at approximately 180° being removed therefrom.
• Figure 7 is a perspective view of a first exemplary embodiment of a heat exchanger tube of the present invention a U-shaped tube section defining a return bend with a concavity formed into the return bend and a pair of straight tube sections connected to the U-shaped section.
• Figure 8 is a top planar view of the first exemplary embodiment of the heat exchanger tube of the present invention shown in Figure 7.
• Figure 9 is a cross-sectional view of the first exemplary embodiment of the heat exchanger tube taken along line 9-9 in Figure 8.
• Figure 10 is a cross-sectional view of the first exemplary embodiment of the heat exchanger tube taken along line 10-10 in Figure 8.
• Figure 11 is a cross-sectional view of the first exemplary embodiment of the heat exchanger tube taken along line 11-11 in Figure 8.
• Figure 12 is a perspective view of a second exemplary embodiment of a heat exchanger serpentine tube of the present invention.
• Figure 13 is a perspective view of a third exemplary embodiment of a heat exchanger tube of the present invention having a generally elliptical-shaped cross- section.
• Figure 14 is a top planar view of the third exemplary embodiment of the heat exchanger tube shown in Figure 13.
• Figure 15 is a cross-sectional view of the third exemplary embodiment of the heat exchanger tube taken along line 15-15 in Figure 14.
• Figure 16 is a cross-sectional view of the third exemplary embodiment of the heat exchanger tube taken along line 16-16 in Figure 14.
• Figure 17 is a cross-sectional view of the third exemplary embodiment of the heat exchanger tube taken along line 17-17 in Figure 14.
• Figure 18 is a top planar view of a fourth exemplary embodiment of the heat exchanger tube of the present invention.
• Figure 19 is a cross-sectional view of the fourth exemplary embodiment of the heat exchanger tube taken along line 19-19 in Figure 18.
• Figure 20 is a cross-sectional view of the fourth exemplary embodiment of the heat exchanger tube taken along line 20-20 in Figure 18.
• Figure 21 is a cross-sectional view of the fourth exemplary embodiment of the heat exchanger tube taken along line 21-21 in Figure 18.
• Figure 22 is a top planar view of the fifth exemplary embodiment of the heat exchanger tube of the present invention.
• Figure 23 is a cross-sectional view of the fifth exemplary embodiment of the heat exchanger tube taken along line 23-23 in Figure 22.
• Figure 24 is a cross-sectional view of the fifth exemplary embodiment of the heat exchanger tube taken along line 24-24 in Figure 22.
• Figure 25 is a cross-sectional view of the fifth exemplary embodiment of the heat exchanger tube taken along line 25-25 in Figure 22.
• Figure 26 is a perspective view of a bend die.
• Figure 27 is a cross-sectional view of the bend die shown in Figure 26.
• Figure 28 is a perspective view of a sixth exemplary embodiment of a heat exchanger.
• Figure 29 is a cross-sectional view of a generally symmetrical U-shaped tube section of a heat exchanger tube formed with a concavity.
• the heat exchanger tube 50 can be any type of tube and is not limited to its use for a heat exchanger.
• the heat exchanger tube 50 includes a tube body 52 that forms a hollow passageway 54.
• the heat exchanger tube 50 has a U-shaped tube section 56 that defines a return bend and a pair of straight tube sections 58a and 58b. Respective ones of the straight tube sections 58a and 58b are connected to the U- shaped section 56 at respective connection locations CL1 and CL2 represented by dashed lines.
• connection locations CL1 and CL2 are approximate locations only that represent approximately where the straight tube sections 58a and 58b are integrally connected to the U-shaped section 56.
• the straight tube sections 58a and 58b extend generally parallel to one another to define an internal space IS as best shown in Figure 7.
• the internal space IS is disposed between and among the U-shaped tube section 56 and the straight tube sections 58a and 58b connected to the U-shaped tube section 56 as well as between the double dashed lines DDL. Further, the U-shaped tube section 56 has a concavity 60 formed into itself.
• the concavity 60 defines a portion of the internal space IS.
• the concavity 60 extends continuously radially along the U- shaped tube section 56 as represented by the arcuate arrow X.
• the concavity 60 terminates adjacent the respective ones of the connection locations CL1 and CL2.
• the concavity 60 has a generally constant depth Dc as the concavity 60 extends continuously radially along the U-shaped tube section 56 as represented by the arcuate arrow Y.
• the concavity 60 has a generally tapering depth Dt that lessens commencing from where the constant depth Dc ends and as the concavity 60 terminates adjacent the respective connection locations CL1 and CL2.
• the respective ones of the straight tube sections 58a and 58b as viewed in cross-section are circular in cross-section.
• the U-shaped tube section 56 as viewed in cross-section is generally kidney-shaped.
• the concavity 60 is also configured in cross-section generally as a U-shape.
• the U-shaped tube section 56 includes a main piece 62 integrally connected to the concavity as viewed in cross-section to define a continuous loop.
• the concavity 60 forms an apex 64 that projects into the hollow passageway 54.
• the main piece 62 has a first imaginary reference point 66 disposed diametric to the apex 64, a second imaginary reference point 68 and a third imaginary reference point 70.
• a first axis Af as viewed in cross-section extends through the apex 64 and the first imaginary reference point 66 which, in turn, divides the U-shaped tube section 56 generally symmetrically in imaginary half-sections 56a and 56b with the apex 64 and the first imaginary reference point 66 being disposed apart from one another at a distance therebetween to define a height H.
• a second axis As as viewed in cross-section perpendicularly intersects the first axis Af and extends through the second imaginary reference point 68 disposed on the half-sections 56b and the third imaginary reference point 70 disposed on the other remaining half-section 56a.
• the second and third imaginary reference points 68 and 70 respectively are disposed apart from one another at a widest distance therebetween on the respective half-sections 56a and 56b to define a width W.
• a ratio of the height H to the width W i.e. H/W
• H/W is in a range of approximately 0.6 and 0.9 based upon inside dimensions of the U-shaped tube section 56 as reflected in Figure 11.
• one of the straight tube sections 58a or 58b defines in cross-section a straight tube cross-sectional area XAst of the hollow passageway 54.
• the U-shaped tube section 56 defines in cross-section a U-shaped tube cross-sectional area XAu of the hollow passageway 54.
• the U-shaped tube cross-sectional area XAu is smaller than the straight tube cross-sectional area XAst. It is estimated that the U-shaped tube cross- sectional area XAu is smaller than the straight tube cross-sectional area XAst by an amount of approximately 20%. However, it is believed that the U-shaped tube cross- sectional area XAu can be smaller than the straight tube cross-sectional area XAst by an approximate range of 10% and 30%.
• FIG. 12 A second exemplary embodiment of a heat exchanger serpentine tube 80 of the present invention is illustrated in Figure 12.
• the heat exchanger serpentine tube 80 can be any type of a tubular serpentine tube for other uses.
• the heat exchanger serpentine tube 80 includes a plurality of straight tube sections 56a, 56b, ...56n and a plurality of U-shaped tube sections 56.
• the plurality of straight tube sections 56a, 56b, ...56n are arranged in a plurality of generally parallel rows and disposed in a common plane P.
• the plurality of U- shaped tube sections 56 are connected to the plurality of straight tube sections 56a, 56b, ...56n in a manner such that a respective one of the U-shaped tube sections 56 defining a return bend connects sequential ones of the plurality of straight tube sections 56a, 56b, ...56n to form a serpentine configuration.
• Each of the sequential ones of straight tube sections 56a, 56b, ...56n are connected to a respective one of the U-shaped sections 56 to define the internal space IS.
• the internal space IS is disposed between and among the respective U-shaped tube section 56 and the sequential ones of the straight tube sections 56a and 56b, for example.
• Each one of the U-shaped tube sections 56 has the concavity 60 as described above.
• Each U-shaped tube section 56 and sequential ones of the straight tube sections 56a, 56b, ...56n are integrally connected at respective connection locations as discussed above.
• each concavity 60 extends continuously and radially along each one of the U-shaped tube sections 56 and terminates adjacent the sequential ones of the straight tube sections 56a and 56b, for example, at the respective connection locations.
• a third exemplary embodiment of a heat exchanger tube 350 of the present invention has a generally elliptical-shaped cross- section.
• Straight tube sections 358a and 358b are elliptically-shaped in cross- section and a U-shaped tube section 356 is also generally elliptically-shaped in cross-section and formed with a concavity 360.
• a fourth exemplary embodiment of a heat exchanger tube 450 of the present invention has a generally flattened circular cross- sectional U-shaped tube section 356.
• Straight tube sections 458a and 458b are circularly-shaped in cross-section and a U-shaped tube section 356 is generally flattened circularly-shaped in cross-section and formed with a concavity 460.
• a fifth exemplary embodiment of a heat exchanger tube 550 of the present invention has a generally flattened elliptical cross- sectional U-shaped tube section 556.
• Straight tube sections 558a and 558b are elliptically-shaped in cross-section and the U-shaped tube section 556 is generally flattened elliptically-shaped in cross-section and formed with a concavity 560.
• the heat exchanger tube of the present invention might be constructed using various combinations of the cross-sectional configurations of the U-shaped tube section and the straight tube sections other than the ones discussed above.
• the straight tube sections might be configured as shown in Figure 9 while the U-shaped tube section integrally connected to these straight tube sections might be configured as shown in Figure 25.
• a sixth exemplary embodiment of the present invention is a method of forming a straight tube into a U-shaped tube.
• the method provides a cylindrically- shaped bend die 608 shown in Figures 26 and 27.
• the bend die 608 has a pair of grooves 610a and 610b extending into and circumferentially about an outer circumferential surface 612 of the bend die 608.
• a protuberance 614 is disposed between the pair of grooves 610a and 610b and projects outwardly relative to the pair of grooves 61 Oa and 610b.
• the protuberance 614 is a ring-like member having a rectangular cross-sectional configuration.
• the straight tube is bent about the bend die 608 180° (or within an approximate range of 170° and 190° or whatever bend angle is desired) in a manner to form the U-shaped tube having the U-shaped tube section defining the return bend and the pair of straight tube sections with the U-shaped tube section having the concavity formed thereinto with the concavity defining a portion of the internal space as discussed above.
• the bend die 608, if split along line S-S shown in Figure 27, can be incorporated into the tube bending tooling 6 shown in Figures 2-6 in order to produce the heat exchanger tubes of the present invention formed with concavities 60.
• a skilled artisan would appreciate that other methods might be used to produce the heat exchanger tube of the present invention formed with concavities 60.
• the heat exchanger tube of the present invention can be made using the bending tooling 6 shown in Figures 2-6 without using the plastic plug mandrel 14, the plastic follower 16, the mandrel rod 34 and the collet 36.
• long lengths of straight tubing can be bent to form heat exchanger serpentine tubes having, for example, 12 straight tube sections and 11 return bends with a fluid passage extending, for example, 300 feet.
• a heat exchanger 710 of the present invention includes an inlet header 712, an inlet connection 714 connected to the inlet header 712, an outlet header 716, an outlet connection 718 connected to the outlet header 716 and a plurality of heat exchanger serpentine tube bodies 80 as described above that interconnect the inlet and outlet headers 712 and 716 respectively.
• the heat exchanger 710 is a conventional heat exchanger except that each one of the plurality of serpentine tube bodies 80 includes a concavity 60 as best shown, for example, in Figures 7, 8 and 11.
• the heat exchanger tube of the present invention with a U-shaped tube section defining a return bend having a concavity formed thereinto results in a reduced pressure loss of the heat exchange fluid as the heat exchange fluid flows therethrough. Further, the heat exchanger tube of the present invention is wrinkle-free even if the heat exchanger tube includes a tight return bend and the heat exchanger tube is fabricated from a material difficult to bend such as stainless steel. Additionally, the serpentine tube of the present invention can be fabricated without the use of a mandrel rod and a mandrel assembly.

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

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• 2006
  • 2006-03-24 US US11/387,786 patent/US20070221365A1/en not_active Abandoned
• 2007
  • 2007-02-28 EP EP07751659A patent/EP1999424A4/de not_active Withdrawn
  • 2007-02-28 WO PCT/US2007/004917 patent/WO2007111804A2/en not_active Ceased
  • 2007-02-28 CN CN200780010527.0A patent/CN101410687A/zh active Pending

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