Heat Exchanger

Abstract

The invention relates to a heat exchanger having at least one partition and surface elements which project from at least one side of the partition and which enlarge the surface of the partition and around which a fluid can flow. The problem addressed by the present invention is that of proposing heat exchangers of low mass with high thermal transmission capacity. This problem is solved by means of a heat exchanger in which the surface elements are formed so as to project in the manner of fins from the partition, and the surface elements have reinforcement beads, wherein the reinforcement beads extend as far as the partition.

Claims

1. Heat exchanger (1) comprising at least one partition and surface elements (3) which project from at least one side of the partition and which enlarge the surface of the partition and around which a fluid can flow, the surface elements (3) being formed so as to project in the manner of fins from the partition and the surface elements (3) having reinforcement beads (4) and face regions (5) located between the reinforcement beads (4), the reinforcement beads (4) extending as far as the partition, characterised in that the reinforcement beads (4) have a circular or oval cross-sectional shape.

2. Heat exchanger (1) according to claim 1, characterised in that the heat exchanger (1) is a ribbed tube heat exchanger having at least one tube (2) for the flow of a first fluid inside the tube (2) and having surface elements (3) which enlarge the surface of the tube (2) on the outside and around which a second fluid can flow in the cross-flow to the fluid 1, the tube (2) forming the partition of the heat exchanger (1).

3. Heat exchanger (1) according to claim 2, characterised in that the reinforcement beads (4) extend orthogonally to the surface of the tube (2).

4. Heat exchanger (1) according to claim 1, characterised in that the reinforcement beads (4) extend through the entire surface element (3) as far as an outer edge of the surface element (3).

5. Heat exchanger (1) according to claim 1, characterised in that the reinforcement beads (4) have a circular cross section and the diameter of the reinforcement beads is at least twice as large as the thickness of the face regions (5) between the reinforcement beads (4) of the surface elements (3).

6. Heat exchanger (1) according to claim 1, characterised in that the reinforcement beads (4) of adjacent surface elements (3) are offset from one another so as to form an offset (7) in a flow direction of the second fluid between the surface elements (3).

7. Heat exchanger (1) according to claim 2, characterised in that the tube (2) of the ribbed tube heat exchanger is formed as an oval tube, the cross section of which is formed from two semicircles and two straight lines connecting the semicircles, the surface elements (3) having an oval shape are arranged in a plane which is orthogonal to a longitudinal axis of the tube and adjacent surface elements (3) are arranged in parallel with one another.

8. Heat exchanger (1) according to claim 7, characterised in that the length of the straight lines (8) of the cross section of the oval tube is at least as large as the diameter (9) of the semicircle of the cross section of the oval tube, in particular 2.5 times as large.

9. Heat exchanger (1) according to claim 6, characterised in that the tube (2) of the ribbed tube heat exchanger is formed as an oval tube, the cross section of which is formed from two semicircles and two straight lines connecting the semicircles, the surface elements (3) having an oval shape are arranged in a plane which is orthogonal to a longitudinal axis of the tube and adjacent surface elements (3) are arranged in parallel with one another.

10. Heat exchanger (1) according to claim 9, characterised in that the length of the straight lines (8) of the cross section of the oval tube is at least as large as the diameter (9) of the semicircle of the cross section of the oval tube, in particular 2.5 times as large.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be explained in more detail below with reference to figures, in which

[0019] FIG. 1 is a perspective view of a heat exchanger according to the invention,

[0020] FIG. 2 shows a fluid flow in the heat exchanger according to the invention,

[0021] FIG. 3 is a view of a ribbed tube heat exchanger according to the invention in a viewing direction along the tube and

[0022] FIG. 4 is a view of the ribbed tube heat exchanger according to the invention in a viewing direction which is transverse to the tube.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] FIG. 1 shows a detail of a heat exchanger 1 according to the invention, specifically a ribbed tube heat exchanger, in a perspective view. The oval tube 2 can be seen in the centre of the object illustrated. The walls of the tube 2 are partitions between a first fluid inside the tube 2 and a second fluid outside the tube 2. Heat is exchanged between the first and the second fluid through the partition or the tube wall without the first and the second fluid coming into contact with one another materially. On the outside, the tube 2 has surface-enlarging ribs which give the ribbed tube heat exchanger its name. In the heat exchanger 1 according to the invention illustrated here, the ribs connected to the tube are formed as substantially two-dimensional surface elements 3 of low volume. In the illustrated embodiment, the surface elements 3 have pin-shaped reinforcement beads 4 having a round cross section. These reinforcement beads 4 extend from the tube 2 as far as the outer edge of the surface elements 3. Between the reinforcement beads 4, the surface element 3 has face regions 5 which have a smaller thickness than the reinforcement beads 4.

[0024] FIG. 2 shows a detail of the heat exchanger from FIG. 1 in a schematic side view of the tube 2. Like reference numerals in the figures indicate the same or similar elements. To avoid repetition, reference is made to the description of FIG. 1. In FIG. 2, the flow of the second fluid outside the tube 2 is illustrated schematically using flow lines 6. The reinforcement beads 4 interfere with a laminar flow between adjacent surface elements 3 by causing turbulences. The turbulences improve the heat transfer between the second fluid and the surface element 3. On the planar side of the oval tube 2, the reinforcement beads 4 of adjacent surface elements 3 are arranged in parallel with one another. In addition, they are each arranged at an offset 7 from one another in the flow direction, which extends from the bottom to the top in the illustration. By means of the offset 7, the turbulences of the individual reinforcement beads 4 are superimposed to form the flow-efficient wave path outlined by the flow lines 6.

[0025] In FIGS. 3 and 4, a very specific design example of the ribbed tube heat exchanger of FIGS. 1 and 2 is illustrated in two different views along the tube 2 and transversely thereto. The tube 2 is here designed as an oval tube which offers, with the same cross section, a lower resistance to the flow illustrated in FIG. 2 by the flow lines 6 than a round tube of the same cross-sectional size. The specific oval tube has an outer diameter 9 of 12 millimetres of the semicircular wall portions thereof and a length 8 of the straight side regions of 30 millimetres. For scaling the tube, it can be generalised that the ratio of the straight length 8 to the diameter 9 is 2.5. The exact size of this ratio can be used as an optimisation parameter in designing the heat exchanger based on predefined framework conditions. It can be seen in FIG. 4 that the face regions 5 have a small thickness of only 1 millimetre and the reinforcement beads 4 having a maximum thickness of 3 mm have an enlarged cross section or a thickness three times larger compared with the face regions 5.

[0026] It can be seen in the detail from FIG. 4 that the left surface element 3 has only three reinforcement beads 4 on the planar surface region of the oval tube 2. The right surface element 3 has, however, four reinforcement beads 4 in the same region. Due to the different number of reinforcement beads 4, the offset 7 is realised and ultimately also the flow path outlined in FIG. 2 by the flow lines 6. Furthermore, the offset of the reinforcement beads ensures different temperature profiles and thus large temperature differences between the fluid 2 and a surface element 3 in each case and therefore large heat flux densities are possible.

[0027] In the illustrated embodiments, the adjacent surface elements 3 are mounted on a tube 2. In other examples (not shown), adjacent surface elements 3 are mounted on adjacent tubes 2 and the ribs of adjacent tubes engage in one another in a comb-like manner. Further embodiments can be derived by a person skilled in the art from the above examples by adapting to a given statement of the problem.

LIST OF REFERENCE NUMERALS

[0028] 1 Heat exchanger

[0029] 2 Tube

[0030] 3 Surface element

[0031] 4 Reinforcement bead of the surface element

[0032] 5 Face region of the surface element

[0033] 6 Flow lines of a fluid between adjacent surface elements

[0034] 7 Offset of reinforcement beads

[0035] 8 Straight line of the oval tube cross section

[0036] 9 Diameter of the semicircle in the oval tube cross section