Arrowhead fin for heat exchange tubing

Abstract

A new heat exchange tube fin design in which a plurality of arrowhead shapes are pressed into or embossed onto each fin, the arrowhead shape defined by two intersecting wedge sections. The pressed arrowhead shapes are grouped into nested pairs, and one of the arrowheads in a pair is pressed as a positive relative to the fin plane and the other of the pair is pressed as a negative relative to the fin plane. The arrowhead pairs are placed in rows parallel to the air flow direction and arrowhead pairs in one row are preferably staggered relative to the arrowhead pairs in the adjacent row along the fin in the air flow direction.

Claims

1. A fin for a heat exchange tube comprising a plurality of fin segments each fin segment comprising arrowhead shapes arranged along a length of said fin segment, said length parallel to an air flow direction along said fin segment; wherein said arrowhead shapes are arranged into arrowhead pairs, each arrowhead pair comprising an indented arrowhead shape and a raised arrowhead shape, where a pointed end of one arrowhead shape of a pair shares a point on the fin segment with a forked end of a second arrowhead shape of the pair, and wherein said pairs of arrowhead shapes are spaced apart along said length, the pointed end of each arrowhead pair separated from the forked end of an adjacent arrowhead pair by a portion of said fin segment that is flat.

2. The fin according to claim 1, wherein said arrowhead pairs each comprise two intersecting arrowhead shapes, a first arrowhead shape comprising said indented arrowhead shape and a second arrowhead shape comprising said raised arrowhead shape.

3. The fin according to claim 1, wherein said arrowhead shapes are arranged in two or more rows on each fin segment, said rows aligned with and parallel to said length of said fin segment.

4. The fin according to claim 1, wherein a first plurality of said arrowhead shapes are pressed in a first direction perpendicular to a plane of said fin segment, and a second plurality of said arrowhead shapes are pressed in a second direction perpendicular to said plane of said fin segment, said second direction opposite to said first direction.

5. The fin according to claim 1, wherein a first arrowhead shape of an arrowhead pair is pressed in a first direction perpendicular to a plane of said fin segment, and a second arrowhead shape of said arrowhead pair is pressed in a second direction perpendicular to said plane of said fin segment, said second direction opposite to said first direction.

6. The fin according to claim 1, wherein arrowhead pairs in a single row are spaced apart from one-another by a factor of 6 to 12 times the spacing between adjacent fin segments.

7. The fin according to claim 1, wherein said arrowheads have a width that is 2 to 3 times the spacing between adjacent fin segments.

8. The fin according to claim 1, wherein said arrowheads have a length that is 5 to 8 times the spacing between adjacent fin segments.

9. A heat exchange tube having a fin attached thereto, said fin comprising a plurality of fin segments, each said fin segment comprising arrowhead shapes arranged along a length of said fin segment, said length parallel to an air flow direction along said fin segment; wherein said arrowhead shapes are arranged into arrowhead pairs, each arrowhead pair comprising an indented arrowhead shape and a raised arrowhead shape, where a pointed end of one arrowhead shape of a pair shares a point on the fin segment with a forked end of a second arrowhead shape of the pair, and wherein said pairs of arrowhead shapes are spaced apart along said length, the pointed end of each arrowhead pair separated from the forked end of an adjacent arrowhead pair by a portion of said fin segment that is flat.

10. The heat exchange tube according to claim 9, wherein said arrowhead pairs each comprise two intersecting arrowhead shapes, a first arrowhead shape comprising said indented arrowhead shape and a second arrowhead shape comprising said raised arrowhead shape.

11. The heat exchange tube according to claim 9, wherein said arrowhead shapes are arranged in two or more rows on each fin segment, said rows aligned with and parallel to said length of said fin segment.

12. The heat exchange tube according to claim 9, wherein a first plurality of said arrowhead shapes are pressed in a first direction perpendicular to a plane of said fin segment, and a second plurality of said arrowhead shapes are pressed in a second direction perpendicular to said plane of said fin segment, said second direction opposite to said first direction.

13. The heat exchange tube according to claim 9, wherein a first arrowhead shape of an arrowhead pair is pressed in a first direction perpendicular to a plane of said fin segment, and a second arrowhead shape of said arrowhead pair is pressed in a second direction perpendicular to said plane of said fin segment, said second direction opposite to said first direction.

14. According to the heat exchange tube of claim 9, wherein arrowhead pairs in a single row are spaced apart from one-another by a factor of 6 to 12 times the spacing between adjacent fin segments.

15. The heat exchange tube according to claim 9, wherein said arrowheads have a width that is 2 to 3 times the spacing between adjacent fin segments.

16. The heat exchange tube according to claim 9, wherein said arrowheads have a length that is 5 to 8 times the spacing between adjacent fin segments.

17. A field erected air cooled industrial steam condenser comprising a plurality of heat exchange tubes, said heat exchange tubes each having a fin attached to an external surface of a flat surface of said tube, said fin comprising a plurality of single fin segments extending between adjacent surfaces of a pair of heat exchange tubes, each said fin segment comprising arrowhead shapes arranged along a length of said fin segment, said length parallel to an air flow direction along said fin; wherein said arrowhead shapes are arranged into arrowhead pairs, each arrowhead pair comprising an indented arrowhead shape and a raised arrowhead shape, where a pointed end of one arrowhead shape of a pair shares a point on the fin segment with a forked end of a second arrowhead shape of the pair, and wherein said pairs of arrowhead shapes are spaced apart along a said length, the pointed end of each arrowhead pair separated from the forked end of an adjacent arrowhead pair by a portion of said fin segment that is flat.

18. The field erected air cooled industrial steam condenser according to claim 17, wherein said arrowhead pairs each comprise two intersecting arrowhead shapes, a first arrowhead shape comprising said indented arrowhead shape and a second arrowhead shape comprising said raised arrowhead shape.

19. The field erected air cooled industrial steam condenser according to claim 17, wherein said arrowhead shapes are arranged in two or more rows on each fin segment, said rows aligned with and parallel to said length of said fin segment.

20. The field erected air cooled industrial steam condenser according to claim 17, wherein a first plurality of said arrowhead shapes are pressed in a first direction perpendicular to a plane of said fin segment, and a second plurality of said arrowhead shapes are pressed in a second direction perpendicular to said plane of said fin segment, said second direction opposite to said first direction.

21. The field erected air cooled industrial steam condenser according to claim 17, wherein a first arrowhead shape of an arrowhead pair is pressed in a first direction perpendicular to a plane of said fin segment, and a second arrowhead shape of said arrowhead pair is pressed in a second direction perpendicular to said plane of said fin segment, said second direction opposite to said first direction.

22. The field erected air cooled industrial steam condenser according to claim 17, wherein arrowhead pairs in a single row are spaced apart from one-another by a factor of 6 to 12 times the spacing between adjacent fin segments.

23. The field erected air cooled industrial steam condenser according to claim 17, wherein said arrowheads have a width that is 2 to 3 times the spacing between adjacent fin segments.

24. The field erected air cooled industrial steam condenser according to claim 17, wherein said arrowheads have a length that is 5 to 8 times the spacing between adjacent fin segments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is perspective view of a fin according to an embodiment of the invention.

(2) FIG. 2 is a side view of a fin according to an embodiment of the invention

(3) FIG. 3 is a set of engineering drawings showing an embodiment of the invention.

(4) FIG. 4 is an excerpt from FIG. 3 showing a cross-sectional view of an embodiment of the invention along line A-A in FIG. 3.

(5) FIG. 5 is an excerpt from FIG. 3 showing a cross-sectional view of an embodiment of the invention along line B-B in FIG. 3.

(6) FIG. 6 is an excerpt from FIG. 3 showing Detail E from FIG. 3.

(7) FIG. 7 is an excerpt from FIG. 3 showing a cross-sectional view of an embodiment of the invention along line F-F in FIG. 3.

(8) FIG. 8 is a side view according to another embodiment of the invention.

(9) FIG. 9 is a perspective view according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(10) Referring to the Figures, and in particular, FIGS. 1, 2, 8, and 9, a plurality of arrowhead shapes 2 are pressed into or embossed onto each fin 4. Each arrowhead shape 2 is defined by two intersecting wedge sections 6a, 6b. The shapes of the volume described by the embossed metal surface and the plane of the flat fin may be characterized as similar in form to a prism. The wedge sections 6a, 6b are triangular in cross section normal to their length. The two intersecting wedge sections 6a, 6b form a pointed end 8 at the leading end of the arrowhead shape 2 and a forked end 10 at the trailing end of the arrowhead shape 2.

(11) The height of each wedge 6a, 6b (in a direction perpendicular to the plane of the fin is 50% or approximately 50% of the distance between adjacent fins 4 (See FIGS. 4, 5, and 7). The leading edges 12 and trailing edges 14 of each wedge are preferably oriented at 30° or approximately 30° from the air flow direction/longitudinal axis of the fin 4. The top wedge section 6a (relative to the location of the tube) forming an arrowhead shape 2 has leading and trailing edges oriented 30° up, and the lower wedge section 6b for each arrowhead shape 2 has leading and trailing edges 12, 14 oriented 30° down.

(12) Referring in particular to FIGS. 1 and 2, the pressed arrowhead shapes 2 may be grouped into pairs 16, where a first arrowhead shape 16a of a pair is immediately upstream of the second arrowhead shape 16b in the pair. The pointed end of the second arrowhead shape 16b may be nested into the back end (or “forked end”) of the first arrowhead shape 16a. Consistent with a preferred embodiment of the invention, FIG. 1 shows one of the arrowheads in a pair pressed as a positive relative to the fin plane (out of the fin plane) and the other of the pair pressed as a negative relative to the fin plane (into the fin plane).

(13) FIGS. 1, 8, and 9 show the arrowhead pairs placed in two rows parallel to the air flow direction. The rows are spaced from one-another normal to the air flow direction one to two times the fin width dimension. The arrowhead pairs in one row are shown staggered relative to the arrowhead pairs in the adjacent row along the fin in the air flow direction so that first arrowhead in the second row is spaced down the air flow direction along the fin by half of the space between arrowhead pairs along the rows.

(14) Referring to FIGS. 1, 2, 8, and 9, the arrowhead pairs in a single row are shown spaced in the direction of air flow according to a multiple of the fin spacing, preferably 6 to 12 times the fin spacing and more preferably 8 or 9 times the fin spacing.

(15) The dimensions of the arrowheads are preferably a function of the fin height. The arrowhead width (normal to the flow in the plane of the fin) is preferably nominally 2 to 3 times fin spacing (0.209″=2.3*0.091″). The arrowhead length (parallel to the flow) is preferably 5 to 8 times the fin spacing (0.091*6.5=0.591) (0.41+0.181=) 0.591.

(16) All arrowhead pressings on a given fin point in the same direction with respect to the flow direction. With each subsequent fin, the arrowhead pressings alternate between pointing in the flow direction and against the flow direction.