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, a tube wall, an outer tube face and an inner tube face, wherein axially parallel or helically circumferential continuous fins are formed on the outer tube face and/or inner tube face which fins continuously run from the tube wall, continuously extending primary grooves are formed between respectively adjacent fins, characterized in that the fins are subdivided along the fin profile into periodically repeating fin sections which are divided into a multiplicity of projections with a projection height, and in that the projections are formed between primary grooves by making cuts into the fins 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.

2. The heat exchanger tube as claimed in claim 1, characterized in that the fin sections of the fins are formed from the fins by secondary grooves running at a pitch angle , measured with respect to the tube longitudinal axis.

3. The heat exchanger tube as claimed in claim 1, characterized in that the projections have alternately changing cutting depths by means of a fin.

4. The heat exchanger tube as claimed in claim 1, characterized in that at least one projection protrudes from the main orientation along the fin profile over the primary groove.

5. The heat exchanger tube as claimed in claim 2, characterized in that the fin sections of the fins are formed in an elongated fashion along the fin profile.

6. The heat exchanger tube as claimed in claim 1, characterized in that a plurality of projections have a surface parallel to the tube longitudinal axis at the point farthest away from the tube wall.

7. The heat exchanger tube as claimed in claim 1, characterized in that the projections vary with respect to one another in terms of projection height, shape and orientation.

8. The heat exchanger tube as claimed in claim 1, characterized in that a projection has a tip, running to a point, at the face facing away from the tube wall.

9. The heat exchanger tube as claimed in claim 1, characterized in that a projection has, at the face facing away from the tube wall, a curved tip whose local curvature radius is decreased starting from the tube wall as the distance increases.

10. The heat exchanger tube as claimed in claim 1, characterized in that the projections have a different shape and/or height from the start of a tube along the tube longitudinal axis as far as the end of the tube located opposite.

11. The heat exchanger tube as claimed in claim 1, characterized in that the tips of at least two projections are in contact with one another or cross over one another along the fin profile.

12. The heat exchanger tube as claimed in claim 1, characterized in that the tips of at least two projections are in contact with one another or cross over one another over the primary groove.

13. The heat exchanger tube as claimed in claim 1, characterized in that at least one of the projections is shaped in such a way that its tip is in contact with the inner tube face or the outer tube face.

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

Description

[0042] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0043] In the drawings:

[0044] FIG. 1 shows a schematic, oblique view of a section of the tube with the inventive structure on the inner tube face;

[0045] FIG. 2 shows a further schematic, oblique view of a section of the tube with the inventive internal structure with secondary groove;

[0046] FIG. 3 shows a schematic view of a fin section with different notch depth;

[0047] FIG. 4 shows a schematic view of a fin section with a structure element which protrudes over the primary groove;

[0048] 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;

[0049] 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;

[0050] FIG. 7 shows a schematic view of a fin section with two projections which are in contact with one another along the fin profile;

[0051] FIG. 8 shows a schematic view of a fin section with two projections which cross over one another along the fin profile;

[0052] FIG. 9 shows a schematic view of a fin section with two projections which are in contact with one another over the primary groove;

[0053] FIG. 10 shows a schematic view of a fin section with two projections which cross over one another over the primary groove.

[0054] Mutually corresponding parts are provided in all figures with the same reference signs.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 for 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

LIST OF REFERENCE SIGNS

[0068] 1 Heat exchanger tube [0069] 2 Tube wall [0070] 21 Outer tube face [0071] 22 Inner tube face [0072] 3 Fin [0073] 31 Fin section [0074] 4 Primary groove [0075] 5 Secondary groove [0076] 6 Projection [0077] 61 Parallel surface [0078] 62 Tip [0079] A Tube longitudinal axis [0080] R Pitch angle [0081] t.sub.1 First cutting depth [0082] t.sub.2 Second cutting depth [0083] t.sub.3 Third cutting depth [0084] h Projection height