EP0798529B1 - Heat transfer tube - Google Patents

Abstract

The tube has a structured inner surface which comprises ribs (14). The ribs have inclined flanks and channels (13) are laterally limited by the ribs. Troughs (18) penetrate the ribs crossways and also have inclined flanks which extend at an angle ( gamma ) deviating from 90 degrees to the tube longitudinal axis (6). Out of two ribs (7,14) running next to each other in a peripheral direction a primary rib has a greater radial extent than the adjacent secondary rib. It is also possible for the primary and secondary ribs to have the same radial extent. They can also run at the same angle ( alpha ) or at different angles to the tube longitudinal axis.

Description

The invention relates to an exchanger tube for a heat exchanger according to the features in the preamble of the claim 1.

Such an exchanger tube counts through the EP 0 692 694 A2 relating to the prior art. Here both point the ribs as well as those laterally delimited by the ribs Channels each have a trapezoidal cross-section. The Flanks of the ribs are flat. The transitions from the flanks on the channel soles are designed with sharp edges. Sharp-edged transitions are also between the flanks and the flat top of the ribs. The Cross-sectional volume of the ribs is about half the size of that Dimensioned cross-sectional volume of the channels. The one another parallel ribs extend under one of 90 ° angle to the pipe longitudinal axis. All the ribs have the same radial extension (height).

The troughs running through the ribs also run at an angle deviating from 90 ° to the pipe longitudinal axis. The flanks of the troughs are convex. The transitions from the flanks on the flat bottoms of the troughs and on the flat head sides of the rib areas between two neighboring hollows of a rib are sharp-edged educated. The depth of the troughs is smaller than the radial one Dimension of the ribs. All troughs are of the same depth educated. In the production of the troughs, this becomes the Deformed material ribs in the front of the troughs Channels deformed into it.

The production of the known exchanger tube takes place in preferably in that first in a rolling process the structure of the later inner surface on one side a metal band, then the metal band a slotted tube with an internal surface structure is formed and then the slot edges are welded become.

Due to the flat head sides and the flat flanks of the It can rib in practical use of the exchanger tube to form difficult-to-tear, the condensation delaying condensate films. So you can Form barrier layers with heat-insulating properties. There are then only a few edges for the evaporation Steam bubble germs available.

The invention is based on the prior art Task, an exchanger tube with an inner To create surface structure, with which a clearly more intensive flow through the channels can be guaranteed can and take advantage of an equally good Evaporation or condensation performance with reduced Connect rib weight.

According to the invention, this object is achieved in the listed in the characterizing part of claim 1 Features.

Because now every second one in the circumferential direction successive primary and secondary ribs one with respect of the adjacent secondary or primary ribs has a different radial extension (height) alternating high primary ribs and low secondary ribs educated. This design brakes the given in the channels Flow rate only insignificantly. Still can become stronger in the channels at suitable points Form turbulence, which ultimately the heat transfer from Intensify flowing fluid on the pipe wall. internal Studies have shown that a clear Performance increase in heat exchange through the alternating Heights of the primary and secondary ribs can be reached.

The embodiment of claim 2 provides that on the one hand all primary ribs and on the other hand all secondary ribs each have the same radial extent. This means, all primary ribs have the same height as well all secondary ribs have the same height.

Internal tests have shown that according to the characteristics of the Claim 3, the primary ribs and the secondary ribs at an angle ≥ 20 °, however ≤ 90 ° to the pipe longitudinal axis. Prefers the primary ribs and the secondary ribs extend at an angle between 20 ° and 40 ° to the pipe longitudinal axis.

The features of claim 4 are of particular advantage connected that when pulling in an exchanger tube, e.g. in the fins of a heat exchanger, in particular by Widening by means of a moving through the exchanger tube Tool, the rounded tops of the primary ribs and the Secondary ribs are only slightly flattened. To this Wise is the formation of difficult to tear open Effectively counteracted condensate films.

The features of claim 5 also contribute decisively to ensure that the heat exchange between the in the exchanger tube flowing fluid and the wall of the exchanger tube is optimized.

A slim rib contour is characterized by the features of the claim 6 scored. Then the flank angle is Primary ribs and the secondary ribs 20 ° to 40 °, preferably 25 °.

A preferred development of the invention Basic idea with a view to further improving the Heat transfer is in the features of claim 7 sees. It was recognized that under at a special angle to the pipe longitudinal axis Primary ribs alternating with one another in the circumferential direction following lower secondary ribs the ratio of the Distance between the median longitudinal planes of two neighboring ones Primary ribs for the radial extension of the secondary ribs of is of particular importance. This ratio is 15: 1 to 8: 1, preferably 10: 1.

In this context, it has a corresponding claim 8 proved to be particularly useful, the distance of the Central longitudinal planes of two adjacent primary ribs between about 0.8 mm and 2.0 mm.

The size of the radial extension of the primary ribs moves advantageous according to claim 9 between about 0.15 mm and 0.40 mm.

Also the cross-sectional area ratio of the primary ribs relative to the secondary ribs plays to achieve a particularly good heat transfer play an important role. According to the features of claim 10, the area ratio of the primary ribs to that of the secondary ribs approximately like 15: 1 to 5: 1, preferably 8: 1 to 6: 1.

According to claim 11, at least the soles of the channels roughened. It is also conceivable to roughen everyone Surfaces of the primary and secondary ribs. Here it can is a micro roughness. Such Roughness is particularly evident in condensation and Evaporation of refrigerants is noticeable when the exchanger tube integrated into a corresponding heat exchanger becomes. The micro roughness makes it possible due to the large fin surfaces for effective evaporation advantageous large number of projections, edges, tips and to provide depressions as vapor bubble nuclei without that on the other hand larger quantities of material for this would be required.

According to claim 12, it is also advantageous if the Depth of the troughs of the radial extension of the primary ribs or the secondary ribs. Preferably extend those formed in adjacent primary or secondary ribs Troughs coaxially one behind the other.

The production of an exchanger tube according to the invention thereby facilitated that according to the characteristics of the Claim 13 the cross section of the troughs about the cross section a rib area separating two adjacent troughs equivalent.

In this context, according to claim 14 the troughs and the rib areas have a triangular shape Cross section on.

Also here are the concave soles of claim 15 Troughs curved more than the tops of the rib areas.

A preferred application of the exchanger tube according to the invention is then according to the features of claim 16 given if it is made of copper or a copper alloy is formed. The exchanger tube can be round or have an oval cross-section. Round exchanger tubes preferably have an outer diameter of about 6 mm to 20 mm on.

In other situations, it can also make sense that according to claim 17, the exchanger tube made of aluminum or an aluminum alloy or according to Claim 18 is formed from iron or an iron alloy.

Figur 1

in der Perspektive einen Längenabschnitt eines Austauscherrohrs;

Figur 2

in der Draufsicht einen Längenabschnitt eines strukturierten Blechbands zur Bildung eines Austauscherrohrs gemäß Figur 1;

Figuren 3a und 3b

in der Perspektive den Ausschnitt III der Figur 2 aus zwei verschiedenen Blickrichtungen;

Figur 4

in vergrößerter Darstellung einen vertikalen Querschnitt entlang der Linie IV-IV der Figur 2;

Figur 5

in vergrößerter Darstellung einen vertikalen Querschnitt entlang der Linie V-V der Figur 2 und

Figur 6

anhand eines Diagramms einen Leistungsvergleich von Koaxialkondensatoren, bestückt mit verschiedenen Innenrohren.

An embodiment of the invention is explained below with reference to the drawings. Show it:

Figure 1

in perspective a length section of an exchanger tube;

Figure 2

in plan view a length section of a structured sheet metal strip to form an exchanger tube according to Figure 1;

Figures 3a and 3b

in perspective the section III of Figure 2 from two different directions;

Figure 4

in an enlarged view a vertical cross section along the line IV-IV of Figure 2;

Figure 5

in an enlarged view a vertical cross section along the line VV of Figure 2 and

Figure 6

Using a diagram, a performance comparison of coaxial capacitors equipped with different inner tubes.

1 in FIG. 1 is a longitudinal section of a longitudinally welded seam Exchanger tube for one otherwise not Heat exchanger shown for condensation and Evaporation of refrigerants.

The exchanger tube 1 consists of oxygen-free, phosphorus deoxidized copper (SF-Cu soft). It has a Outside diameter D of 9.52 mm.

The exchanger tube, which is circular in the outside and inside cross section 1 has a smooth outer surface 2 and one structured inner surface 3.

The exchanger tube 1 is produced from a Flat sheet metal strip, not shown, on both sides SF-Cu. The sheet metal strip is a one-step roll stamping process subjected, whereby according to the representation of Figures 2 and 3 one side of the then deformed metal strip 4 smooth remains (the later outer surface 2 of the exchanger tube 1) and the other side with a textured surface (the later inner surface 3 of the exchanger tube 1) is provided. Only those used for welding Edge areas 5 of the metal strip 4 (FIG. 2) remain unstructured. After the roll stamping, the sheet metal strip 4 is closed molded into a slotted tube and then welded lengthwise as well as divided into lengths.

The structure of the inner surface 3 of the exchanger tube 1 (see Figures 2 to 5) comprises at an angle α of 25 ° parallel to the longitudinal axis 6 of the exchanger tube 1 Primary ribs 7 (FIGS. 2 to 4) with inclined flanks 8 (Figures 3a / b and 4). The flank angle β of the primary ribs 7 is 25 ° in the exemplary embodiment and the distance A is Middle longitudinal planes MLE of two adjacent primary ribs 7 1.0 mm (Figure 4). Its height H (radial extension) is to 0.30 mm (Figure 4). The primary ribs 7 connecting wall 9 of the exchanger tube 1 has a thickness of 0.30 mm (Figure 4).

To clarify the respective line of sight is in the Figures 3a and 3b, the longitudinal axis 6 of the exchanger tube entered. Furthermore, from FIGS. 3a and 3b recognize that the crests 10 of the primary ribs 7 flat are trained. The throats 11 between the flanks 8 and the flat soles 12 of the channels 13 are rounded (Figure 4). The cross-sectional volume of the primary ribs 7 is clear smaller than the cross-sectional volume of the channels 13 between dimensioned the primary ribs 7.

Figures 2 to 4 also show that between two adjacent primary ribs 7 in height H1 (radial extension) smaller secondary ribs 14 extend. The height H1 of the secondary ribs 14 is 0.10 mm. The crests 15 of the secondary ribs 14 are also rounded. The throats 16 between the flanks 17 of the Secondary ribs 14 and the soles 12 of the channels 13 are also rounded. The flank angle β is, as with Flank angle β of the primary ribs 7 25 °.

The secondary ribs 14 run at the same angle α to Longitudinal tube axis 6 as the primary ribs 7. The distance A1 parallel secondary ribs 14 corresponds to the distance A. parallel primary ribs 7 (Figure 2).

As Figures 3a and 5 illustrate, each primary rib is 7 seen in longitudinal section with parallel to each other troughs 18 which are triangular in cross section Mistake. As shown in this context, Figure 2 are Troughs 18 of adjacent primary ribs 7 at an angle γ of 35 ° to the pipe longitudinal axis 6 aligned one behind the other. The between the central longitudinal plane MLE of the primary ribs 7 and the central longitudinal planes MLE1 of the troughs 18 included Angle δ is 60 °. The distance A2 in the longitudinal direction a primary rib 7 of adjacent troughs 18 is 0.4 mm (Figures 2 and 5).

The troughs 18 have a depth T, which is the height H of the Primary ribs 7 corresponds. The flanks 19 of the troughs 18 are just trained. Between the troughs 18 are trapezoidal Rib areas 20 formed, the tops 21 are flat. The Bottoms 22 of the troughs 18 are rounded (Figure 5).

As shown in FIG. 3a, the secondary ribs 14 also have Troughs 23 according to the arrangement and configuration of the Troughs 18 in the primary ribs 7. In this respect, the hollows 23 not explained again below.

At least the soles 12 of the channels 13 are not shown in FIG shown with a micro roughness is generated directly during roll embossing.

Due to the structured inner surface 3, the exchanger tube 1 illustrated in FIG. 1 has a significantly better heat transfer coefficient k '(not only compared to an exchanger tube 24 with a smooth inner surface, but also to an internally grooved exchanger tube 25 (commercially available V-profile)). W / m ² K) (Figure 6).

This fact is due to the comparative Examinations created diagram according to Figure 6 without additional Explanations recognizable.

REFERENCE NUMBERS

1 -

Exchanger

2 -

outer surface v. 1

3 -

inner surface v. 1

4 -

metal strip

5 -

Marginal areas v. 4

6 -

tube longitudinal axis

7 -

primary fins

8th -

Flanks v. 7

9 -

Wall v. 1

10 -

Kuppen v. 7

11 -

Throats between 8 and 12

12 -

Soles v. 13

13 -

channels

14 -

secondary ribs

15 -

Kuppen v. 14

16 -

Throats between 17 and 12

17 -

Flanks v. 14

18 -

Troughs in 7

19 -

Flanks v. 18

20 -

rib areas

21 -

Kuppen v. 20

22 -

Floors v. 18

23 -

Troughs in 14

24 -

Exchanger tube, smooth

25 -

Exchanger tube, grooved

α -

Angle between 7 or 14 u. 6

β -

Flank angle v. 7 u. 14

γ -

Angle between 18 u. 6

δ -

Angle between MLE and MLE1

A -

Distance from 7

A1 -

Distance from 14

A2 -

Distance from 18

D -

Diameter of 1

D1 -

Thickness v. 9

H -

Height of 7

H1 -

Height of 14

MLE

Median longitudinal plane v. 7

MLE1-

Median longitudinal plane v. 18

T -

Depth of 18

Claims (18)

1. Exchanger tube for a heat exchanger which exhibits a textured internal surface (3) which is formed of ribs (7, 14) running at an angle (α) of other than 90° to the longitudinal axis (6) of the tube and having inclined flanks (8, 17), channels (13) bounded laterally by the ribs (7, 14), and troughs (18, 23) passing transversely through the ribs (7, 14) and also having inclined flanks (19), which extend at an angle (γ) of other than 90° to the longitudinal axis (6) of the tube, characterised in that of two ribs (7, 14) running next to one another in the circumferential direction, one of the ribs, the primary rib (7), exhibits a greater radial extension (H) than the neighbouring rib, the secondary rib (14), so that high primary ribs (7) and low secondary ribs (14) are formed in alternation, and the ratio of the radial extension (H) of the primary ribs (7) to the radial extension (H1) of the secondary ribs (14) is approximately 3 : 1.
2. Exchanger tube according to claim 1, characterised in that in each case all the primary ribs (7) and all the secondary ribs (14) exhibit the same radial extension (H and H1 respectively).
3. Exchanger tube according to claim 1 or 2, characterised in that the primary ribs (7) and the secondary ribs (14) run at an angle (α) of at least 20° and at most 90°, preferably 20° to 40°, to the longitudinal axis (6) of the tube.
4. Exchanger tube according to one of claims 1 to 3, characterised in that both the primary ribs (7) and the secondary ribs (14) exhibit rounded crests (10, 15) and flat flanks (8, 17).
5. Exchanger tube according to one of claims 1 to 4, characterised in that the flanks (8) of the primary ribs (7) run into the bottoms (12) of the channels (13) via rounded fillets (11) and the flanks (17) of the secondary ribs (14) run into the bottoms (12) of the channels (13) via rounded fillets (16).
6. Exchanger tube according to one of claims 1 to 5, characterised in that the flank angle (β) of the primary ribs (7) and the secondary ribs (14) is 20° to 40°, preferably 25°.
7. Exchanger tube according to one of claims 1 to 6, characterised in that the ratio of the distance (A) between the median longitudinal planes (MLE) of two neighbouring primary ribs (7) to the radial extension (H1) of the secondary ribs (14) is 15 : 1 to 8 : 1, preferably 10 : 1:.
8. Exchanger tube according to one of claims 1 to 7, characterised in that the distance (A) between the median longitudinal planes (MLE) of two neighbouring primary ribs (7) lies between approximately 0.8 mm and 2.0 mm.
9. Exchanger tube according to one of claims 1 to 8, characterised in that the radial extension (H) of the primary ribs (7) lies between 0.15 mm and 0.40 mm.
10. Exchanger tube according to one of claims 1 to 9, characterised in that - viewed in cross-section - the ratio of the area of the primary ribs (7) to that of the secondary ribs (14) is approximately 15 : 1 to 5: 1, preferably 8 : 1 to 6 : 1.
11. Exchanger tube according to one of claims 1 to 10, characterised in that at least the bottoms (12) of the channels (13) are roughened.
12. Exchanger tube according to one of claims 1 to 11, characterised in that the depth (T) of the troughs (18, 23) corresponds to the radial extension (H) of the primary ribs (7) or (H1) of the secondary ribs (14).
13. Exchanger tube according to one of claims 1 to 12, characterised in that the cross-section of the troughs (18, 23) roughly corresponds to the cross-section of a rib area (20) separating two neighbouring troughs (18, 23).
14. Exchanger tube according to claim 13, characterised in that the troughs (18, 23) and the rib areas (20) exhibit a triangular cross-section.
15. Exchanger tube according to one of claims 13 or 14, characterised in that the bottoms (22) of the troughs (18, 23) are curved more sharply than the crests (21) of the rib areas (20).
16. Exchanger tube according to one of claims 1 to 15, characterised in that it is formed of copper or a copper alloy.
17. Exchanger tube according to one of claims 1 to 15, characterised in that it is formed of aluminium or an aluminium alloy.
18. Exchanger tube according to one of claims 1 to 15, characterised in that it is formed of iron or an iron alloy.

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