Heat exchanger tube

Abstract

The invention relates to a heat exchanger tube (1) having a tube longitudinal axis (A), a tube wall (2), an outer tube face (21) and an inner tube face (22), wherein axially parallel or helically circumferential continuous fins (3) are formed on the outer tube face (21) and/or inner tube face (22) which fins continuously run from the tube wall, and continuously extending primary grooves (4) are formed between respectively adjacent fins (3). According to the invention, the fins (3) along the fin profile are subdivided into periodically repeating fin sections (31) which are divided into a multiplicity of projections (6) with a projection height (h), wherein the projections (6) are formed between primary grooves (4) by making cuts into the fins (3) at a cutting depth transversely with respect to the fin profile to form fin segments and by raising the fin segments in a main orientation along the fin profile.

Claims

1. A heat exchanger tube having a tube longitudinal axis, the heat exchanger tube comprising: a tube wall, an outer tube face and an inner tube face; axially parallel or helically circumferential fins formed on at least one of the outer tube face or the inner tube face, the fins being formed from the tube wall and extending continuously along tube wall; continuously extending primary grooves formed between respectively adjacent fins; and each of the fins are subdivided into a plurality of fin sections, the fin sections of each fin periodically repeating longitudinally along the respective fin such that adjacent pairs of the fin sections are longitudinally spaced-apart from one another along the respective fin by a gap disposed therebetween, each fin section being divided into a multiplicity of projections each having a projection height, wherein the gap between adjacent fin sections of each fin has a greater longitudinal dimension than a dimension of a space defined longitudinally between adjacent projections of each fin section, and the projections are formed between the primary grooves by making cuts into the fins at a cutting depth transversely with respect to a longitudinal extent of the fin to form fin segments and by raising the fin segments in a main orientation along the longitudinal extent of the fin.

2. The heat exchanger tube as claimed in claim 1, wherein the gaps separate the fin sections of each fin and are formed in the respective fin, each gap comprising a secondary groove, the secondary grooves running at a pitch angle, wherein the pitch angle is measured with respect to the tube longitudinal axis.

3. The heat exchanger tube as claimed in claim 1, wherein the projections of the respective fin sections are formed by making cuts into the respective fin, the cuts having alternately changing cutting depths.

4. The heat exchanger tube as claimed in claim 1, wherein at least one of the projections of each fin section protrudes from the main orientation over an adjacent one of the primary grooves.

5. The heat exchanger tube as claimed in claim 1, wherein the fin sections extend in an elongated fashion along the respective fin.

6. The heat exchanger tube as claimed in claim 1, wherein some of the projections of the respective fin sections have a surface parallel to the tube longitudinal axis at a point farthest away from the tube wall.

7. The heat exchanger tube as claimed in claim 1, wherein the projections of the respective fin sections vary with respect to one another in projection height, shape and orientation.

8. The heat exchanger tube as claimed in claim 1, wherein one of the projections of the respective fin sections has a face which faces away from the tube wall and a tip running to a point at the face.

9. The heat exchanger tube as claimed in claim 1, wherein one of the projections of the respective fin sections has a face facing away from the tube wall and a curved tip on the face whose local curvature radius decreases starting from the tube wall as a distance from the tube wall increases.

10. The heat exchanger tube as claimed in claim 1, wherein the projections of the respective fin sections have at least one of a different shape or a different height from a start of the tube along the tube longitudinal axis as far as an end of the tube located opposite the start thereof.

11. The heat exchanger tube as claimed in claim 1, wherein tips of at least two of the projections of the respective fin sections are in contact with one another or cross over one another along the longitudinal extent of the respective fin.

12. The heat exchanger tube as claimed in claim 1, wherein tips of at least two of the projections of the respective fin sections are in contact with one another or cross over one another over an adjacent one of the primary grooves.

13. The heat exchanger tube as claimed in claim 1, wherein at least one of the projections of the respective fin sections has a tip which is shaped such that the tip is in contact with the at least one outer tube face or inner tube face.

14. The heat exchanger tube as claimed in claim 1, wherein the projections of the respective fin sections are formed from their respective fins, wherein at least one of the fins differs from the others in at least one of fin height, fin spacing, fin tip, fin intermediate space, fin angle of aperture or twist.

15. The heat exchanger tube as claimed in claim 1, wherein the space defined between adjacent projections of the respective fin sections comprises a cut out notch area of the respective fin, each cut out notch area having a notch depth, the notch depths of each fin section being different from one another.

16. The heat exchanger tube as claimed in claim 1, wherein each gap comprises an area of the respective fin which is free of said projections.

17. A heat exchanger tube having a longitudinal tube axis, the heat exchanger tube comprising: a tube wall, an outer tube face and an inner tube face facing away from the outer tube face; a plurality of elongate fins formed from the tube wall and extending continuously along at least one of the outer tube face or the inner tube face; and a plurality of elongate grooves extending continuously along the tube wall, each groove extending between two adjacent fins; wherein each of the fins has a plurality of elongate fin sections extending therealong and being longitudinally spaced and separated from one another by respective gaps, each of the fin sections comprising a plurality of projections extending outwardly in a direction away from the at least one outer tube face or inner tube face such that each of the projections has a projection height, adjacent ones of the projections of each fin section being separated from one another by a cut out notched area of the respective fin, and the gap disposed between longitudinally adjacent fin sections has a greater longitudinal dimension than a longitudinal dimension of the cut out notched area disposed between two adjacent projections.

18. The heat exchanger tube as claimed in claim 17, wherein each cut out notched area of the respective fin sections has a notch depth, the notch depths of each fin section being different from one another.

19. The heat exchanger tube as claimed in claim 17, wherein each gap comprises an area of the respective fin which is free of said projections.

20. The heat exchanger tube as claimed in claim 17, wherein the plurality of grooves comprise primary grooves, the gaps which separate the respective fin sections of each fin are formed in the respective fin, each gap comprising a secondary groove, the secondary grooves running at a pitch angle measured with respect to the longitudinal tube axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 shows a schematic, oblique view of a section of the tube with the inventive structure on the inner tube face;

(3) FIG. 2 shows a further schematic, oblique view of a section of the tube with the inventive internal structure with secondary groove;

(4) FIG. 3 shows a schematic view of a fin section with different notch depth;

(5) FIG. 4 shows a schematic view of a fin section with a structure element which protrudes over the primary groove;

(6) FIG. 5 shows a schematic view of a fin section with a projection which is curved at the tip in the direction of the fins;

(7) FIG. 6 shows a schematic view of a fin section with a projection having a parallel surface at the point farthest away from the tube wall;

(8) FIG. 7 shows a schematic view of a fin section with two projections which are in contact with one another along the fin profile;

(9) FIG. 8 shows a schematic view of a fin section with two projections which cross over one another along the fin profile;

(10) FIG. 9 shows a schematic view of a fin section with two projections which are in contact with one another over the primary groove;

(11) FIG. 10 shows a schematic view of a fin section with two projections which cross over one another over the primary groove.

(12) Mutually corresponding parts are provided in all figures with the same reference signs.

DETAILED DESCRIPTION

(13) FIG. 1 shows a schematic, oblique view of a section of the tube of the heat exchanger tube 1 with the inventive structure on the inner tube face 22. The heat exchanger tube 1 has a tube wall 2, an outer tube face 21 and an inner tube face 22. Helically circumferential continuous fins 3 are formed which continuously run from the tube wall 2 on the inner tube face 22. The tube longitudinal axis A runs at a certain angle with respect to the fins. Continuously extending primary grooves 4 are formed between respectively adjacent fins 3.

(14) The fins 3 are subdivided along the fin profile into periodically repeating fin sections 31 which are divided into a multiplicity of projections 6. The projections 6 are formed between primary grooves 4 by making cuts into the fins 3 at a cutting depth transversely with respect to the fin profile to form fin segments and by raising the fin segments in a main orientation along the fin profile.

(15) In FIG. 1, the fin sections 31 of the fins 3 are formed in an elongated fashion along the fin profile. In this case, one fin section 31 is delimited from the following section by a non-cut partial region of a fin 3. The original height of the primary fin 3 can also be still partially retained there.

(16) FIG. 2 shows a further schematic, oblique view of a section of the tube of the heat exchanger tube 1 with the inventive structure on the inner tube face 22 having secondary grooves 5. The fins 3 are in turn subdivided along the fin profile into periodically repeating fin sections 31 which are divided into a multiplicity of projections 6.

(17) In FIG. 2, the fin sections 31 of the fins 3 are in turn formed in an elongated fashion along the fin profile. One fin section 31 is delimited with respect to the following section by a secondary groove 5 running at a pitch angle , measured with respect to the tube longitudinal axis A. The secondary groove 5 can have a small notch depth or, as in the examplary embodiment shown, extend to close to the primary groove with a large notch depth.

(18) FIG. 3 shows a schematic view of a fin section 31 with a different cutting depth or notch depth t.sub.1, t.sub.2, t.sub.3. The terms cutting depth and notch depth express the same concept within the scope of the invention. The projections 6 have alternately changing cutting depths t.sub.1, t.sub.2, t.sub.3 by means of a fin 3. The original, shaped helically circumferential continuous fin 3 is indicated by dashed lines in FIG. 3. The projections 6 are formed from said fin 3 by making cuts into the fin 3 at a cutting depth t.sub.1, t.sub.2, t.sub.3 transversely with respect to the fin profile to form fin segments and by raising the fin segments in a main orientation along the fin profile. The different cutting depths t.sub.1, t.sub.2, t.sub.3 are consequently measured at the notch depth of the original fin in the radial direction.

(19) The projection height h in FIG. 2 is drawn as the dimension of a projection in the radial direction. The projection height h is then the distance starting from the tube wall as far as the point of the projection which is farthest away from the tube wall in the radial direction.

(20) The notch depth t.sub.1, t.sub.2, t.sub.3 is the distance measured in the radial direction starting from the original fin tips as far as the deepest point of the notch. In other words: The notch depth is the difference between the original fin height and the residual fin height remaining at the deepest point of a notch.

(21) FIG. 4 shows a schematic view of a fin section 31 with a structure element 6 which protrudes over the primary groove 4; This is a projection 6 which extends along the fin profile from the main orientation with the tip 62 over the primary groove 4. The wider the protrusion is made, the more intensive the disruption of the boundary layer of the fluid which is formed in the fin intermediate space, which brings about improved transfer of heat.

(22) FIG. 5 shows a schematic view of a fin section 31 with a projection 6 which is curved at the tip 62 in the direction of the fin. The projection 6 has a changing curvature profile at the curved tip 62. In this context, the local curvature radius decreases starting from the tube wall as the distance increases. In other words: The curvature radius becomes smaller along the line to the tip 62 which line is indicated by the points P1, P2, P3. This has the advantage that the condensate which is produced at the tip 62 in the case of two-phase fluids is transported more quickly to the fin foot by the increasing convex curvature. This optimizes the transfer of heat when liquefaction occurs.

(23) FIG. 6 shows a schematic view of a fin section 31 with a projection 6 with a parallel surface 61 at the point which is farthest away from the tube wall, in the region of the tip 62.

(24) FIG. 7 shows a schematic view of a fin section 31 with two projections 6 which are in contact with one another along the fin profile. Furthermore, FIG. 8 shows a schematic view of a fin section 31 with two projections 6 which cross over one another along the fin profile. FIG. 9 shows also a schematic view of a fin section 31 with two projections which come into contact with one another over the primary groove 4. FIG. 10 shows a schematic view of a fin section 31 with two projections 6 which cross over one another over the primary groove 4.

(25) With the structure elements illustrated in FIGS. 7 to 10, it is advantageous, specifically in the reversible operating mode with two-phase fluids, that they form a type of cavity for the evaporation. The cavities of this particular type form the starting points for bubble nuclei of an evaporating fluid.