Heat exchanger tube

Abstract

The invention relates to a heat exchanger tube having a tube longitudinal axis, wherein fins extend continuously from the tube wall on the tube outer face and/or the tube inner face, or extend axially parallel thereto or in the form of a helix. Continuously extending primary grooves are formed between adjacent fins, said fins have at least one structured area on the tube outer face and/or tube inner face, and the structured area has a plurality of projections of a projection height projecting from the surface, the projections being separated by notches. According to the invention, a plurality of projections are deformed relative one another in pairs to such an extent that cavities are formed between adjacent projections. Furthermore, according to the invention, a plurality of projections are deformed in the direction of the tube wall such that cavities are formed between a respective projection and the tube wall.

Claims

1. 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; axially parallel or helically circumferential continuous fins formed from the tube wall on at least one of the outer tube face or the inner tube face; continuously extending primary grooves formed between respectively adjacent fins; the fins having at least one structured region on the at least one outer tube face or inner tube face; the structured region having a multiplicity of projections which project from the at least one outer tube face or inner tube face with a projection height, wherein the projections are separated by notch formations and wherein each projection has a tip; a plurality of the projections being shaped with respect to each other in pairs such that cavities are formed between adjacent projections, the tips of two of the projections disposed adjacent one another along the same fin are in contact with one another and are a first pair of contacting projections, and the tips of two of the projections disposed adjacent one another along the same fin are in contact with one another and are a second pair of contacting projections, the first and second pairs of contacting projections being disposed along the same fin, and at least one stand-alone projection is disposed between, and on the same fin as, the first and second pairs of contacting projections.

2. The heat exchanger tube as claimed in claim 1, wherein the notch formations are formed between the primary grooves by cutting the fins at a cutting depth transversely with respect to a longitudinal extent of the fin to form fin layers and by raising the fin layers in a main orientation along the longitudinal extent of the fin.

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

4. The heat exchanger tube as claimed in claim 1, wherein at least one of the projections has a face facing away from the tube wall and the tip of the at least one projection runs to a point at the face.

5. The heat exchanger tube as claimed in claim 1, wherein at least one of the projections has a face facing away from the tube wall and the tip of the at least one projection is curved on the face, the curved tip having a local curvature radius which decreases starting from the tube wall as a distance from the tube wall increases along the at least one projection.

6. The heat exchanger tube as claimed in claim 1, wherein the two projections of each of the first and second pairs of contacting projections each have a concave face, the concave faces of the two projections of the first and second pairs of contacting projections facing one another and defining the respective cavity therebetween.

7. 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; each fin having at least one structured region, the structured region including a plurality of projections disposed one after another along a longitudinal extent of the fin and separated from one another by respective notch formations, the projections extending outwardly from the at least one outer tube face or inner tube face such that each of the projections has a projection height, first and second pairs of the projections disposed along the same fin each including two projections disposed immediately adjacent one another and shaped to form a cavity therebetween, the projections of the first pair of projections disposed along the same fin have respective tips disposed in contact with one another, the projections of the second pair of projections disposed along the same fin have respective tips disposed in contact with one another, and at least one stand-alone projection is disposed between, and on the same fin as, the first and second pairs of projections.

8. The heat exchanger tube as claimed in claim 7, wherein the projections of the first and second pairs of projections have respective concave faces which face one another and define the respective cavity therebetween.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a schematic, oblique view of a tube detail of the heat exchanger tube with an inventive structure on the inner tube face;

(3) FIG. 2 is a schematic, oblique view of a tube detail of the heat exchanger tube with a further inventive structure;

(4) FIG. 3 is a schematic, oblique view of a tube detail of the heat exchanger tube with a further inventive structure on the inner tube face;

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

(6) FIG. 5 shows a schematic view of a fin section with two projections which are in contact with one another along the fin profile;

(7) FIG. 6 shows a schematic view of a fin section with two projections which cross over one another along the fin profile;

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

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

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

DETAILED DESCRIPTION

(11) FIG. 1 is a schematic, oblique view of a tube detail of the heat exchanger tube 1 with an 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 from the tube wall 2 on the inner tube face 22. The longitudinal tube axis A runs at a certain angle with respect to the fins 3. Continuously extending primary grooves 4 are formed between respectively adjacent fins 3.

(12) A plurality of projections 6 are shaped with respect to one another in pairs in such a way that cavities 10 are formed between adjacent projections 6. In this context, the tips 61 of at least two projections 6 are in contact with one another along the fin profile.

(13) The projections 6 are formed between primary grooves 4 by cutting the fins 3 at a cutting depth transversely with respect to the fin profile to form fin layers and by raising the fin layers in a main orientation along the fin profile. The notch formations 7 between the projections 6 can also be formed with a changing notch depth in one fin 3.

(14) FIG. 2 shows a schematic, oblique view of a tube detail of the heat exchanger tube 1 with a further inventive structure. A plurality of projections 6 are shaped with respect to one another in pairs in such a way that cavities are formed between adjacent projections 6. In this context, the tips 61 of at least two projections 6 extend over the primary groove 4 and are in contact with one another. However, the tips 61 of projections 6 which are shaped with respect to one another in pairs can also be at a certain distance from one another. However, this distance is so small that effective cavities 10 are still formed.

(15) The projections 6 are in turn formed between primary grooves 4 by cutting the fins 3 at a cutting depth transversely with respect to the fin profile to form fin layers and by raising the fin layers in a main orientation along the fin profile. The notch formations 7 between the projections 6 can also be formed with a changing notch depth in one fin 3.

(16) FIG. 3 shows a schematic, oblique view of a tube detail of the heat exchanger tube 1 with a further inventive structure on the inner tube face 22. A plurality of projections 6 are shaped in the direction of the tube wall 2, with the result that cavities 10 are formed between a respective projection and the tube wall 2.

(17) In this context, the distance between the tips 61 of a projection and the tube wall is shorter than the residual fin height. Consequently a hook-like shape is produced. However, a projection 6 can be shaped in such a way that its tip 61 is in contact with the inner tube side 22. In this case which is not illustrated in FIG. 3, an eyelet-like shape is preferably produced. The projections 6 are in turn formed by cutting the fins 3 in a way analogous to FIGS. 1 and 2.

(18) FIG. 4 shows a schematic view of a fin section 31 with a different 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 notch depths t.sub.1, t.sub.2, t.sub.3 by means of a fin 3. The original, shaped helically circumferential fin 3 is indicated by dashed lines in FIG. 4. The projections 6 are formed from said fin 3 by cutting the fin 3 at a notch/cutting depth t.sub.1, t.sub.2, t.sub.3 transversely with respect to the fin profile to form fin layers and by raising the fin layers in a main orientation along the fin profile. The different notch/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 is expediently defined in FIG. 2 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 on the projection which is furthest 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 tip 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. 5 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. 6 shows a schematic view of a fin section 31 with two projections 6 which cross over one another along the fin profile. FIG. 7 also shows a schematic view of a fin section 31 with two projections 6 which are in contact with one another over the primary groove. FIG. 8 shows a schematic view of a fin section 31 with two projections 6 which cross over one another over the primary groove.

(22) With the structure elements illustrated in FIGS. 5 to 8, it is advantageous, specifically in the reversible operating mode with two-phase fluids, that they form a type of cavity 10 for the evaporation. The cavities 10 of this particular type form the starting points for bubble nuclei of an evaporating fluid.