EP2909560B1 - Flat pipe - Google Patents

Description

Technical area

The invention relates to a flat tube according to the preamble of claim 1. The invention also relates to a heat exchanger with such flat tubes.

State of the art

In the prior art, flat tubes have become known as so-called rectangular tubes, which have two flat, broad side walls, which are connected by flat side walls. The corners between the flat wide and the flat side walls are provided with a small radius. These flat tubes are essentially rectangular and are used for various types of heat exchanger.

For use in exhaust gas coolers, these rectangular tubes are provided with projections projecting into the interior in order to improve the heat transfer between the flowing exhaust gas and the wall. The projections are also referred to as winglets. Outwardly projecting protrusions are also used as spacers between adjacent flat tubes, see also DE 10 2004 045 923 A1 , A flat tube according to the preamble of claim 1 is made EP 2 199 722 A2 known.

Also known in the art so-called flat round flat tubes, which have two flat wide side walls which are connected by arcuate side walls. These flat tubes are formed substantially rectangular-like with bulged side walls and are also used for different heat exchanger types.

For use in exhaust gas coolers, these flat-round flat tubes are provided with protrusions protruding into the interior space in the flat, broad side walls in order to improve the heat transfer between the exhaust gas flowing through and the wall. However, since the width of the flat side wall is reduced in this flat tubes compared to the rectangular tubes, because the lateral arc requires more space than a rectangular tube, the flat side wall, the embossed projections are narrower and the projections can not protrude into the regions of the fillets. This causes a reduced heat transfer in the flat round flat tube compared to the rectangular tube. Comparative measurements show reductions of up to 10%.

The flat-round flat tubes, however, have the advantage that they exhibit a significantly higher service life in the case of thermal change loads than comparable rectangular tubes, since the fillets have a higher strength than the flat side walls of the rectangular tubes.

Presentation of the invention, object, solution, advantages

Therefore, it is the object of the present invention to provide a flat-round flat tube, which achieves at least the same high power density as a comparable rectangular tube and at the same time retains the higher thermal shock resistance. In addition, it is the task of creating a heat exchanger with such flat tubes.

The object of the present invention with regard to the flat tube is achieved by a flat tube having the features according to claim 1.

An embodiment of the invention relates to a flat tube with two opposing substantially flat first walls arranged parallel to each other and with two arcuate second walls connecting the two flat first walls, with an interior for flowing through a medium, wherein in at least one of the flat first walls in the Interior projecting projections are provided, which are provided in the arcuate second walls in the interior protruding projections. This ensures that the flat round flat tube is increased with its high thermal shock resistance in the power density, because now in the area of the fillets in the interior protruding projections are provided. As a result, the interior areas are reduced, which can be flowed through by projections without turbulence.

It is advantageous if both opposing flat first walls each have projections projecting into the interior space. This leads to an increased power density.

It is particularly advantageous if both opposing arcuate second walls have protrusions protruding into the interior space. As a result, the power density is increased because protrusions are now provided on both end-side fillets.

According to the invention, at least one, preferably both, of the two opposite flat first walls have outwardly directed projections. As a result, nubs are created as spacers between adjacent flat tubes, so that the distance of the tubes is defined and the flat tubes can touch only in small areas.

It is also expedient if the inwardly directed projections of the flat first walls are arranged at a first repetition rate along the longitudinal axis of the flat tube. This results in a simpler production, because the projections can be embossed periodically by means of embossing rollers or correspondingly repeating embossing tools.

It is also advantageous if the inwardly directed projections of the arcuate second walls are arranged at a second repetition rate along the longitudinal axis of the flat tube. As a result, the projections can be generated periodically recurring by simplified tool design.

It is useful if a repetition rate is an integer multiple, including 1, the other repetition rate. As a result, the total period length is limited, which in turn facilitates a length variation of the tubes, and reduces the expense of periodically repeating tools.

It is particularly expedient if the second repetition rate is twice as high as the first repetition rate. With this constellation, the same power densities could be achieved with the flat-round flat tube, with the same pressure drop, as with a comparable rectangular tube.

It is also expedient if the protruding projections of the flat first walls are arranged in an X-shaped and / or O-shaped manner. As a result, an optimized flow can be achieved.

It is particularly advantageous if the outwardly projecting projections of the flat walls are arranged between the o-shaped protrusions of the first wall which project into the interior space.

Furthermore, it is expedient if the projections projecting into the interior of opposing first walls are arranged complementary to each other, so that an x-shaped arrangement in a first wall of an o-shaped arrangement opposite to an opposite first wall. As a result, an improved formation of turbulence is achieved.

It is also expedient if the projections provided in the arcuate second walls and projecting into the interior space have an oval cross-section.

It is also advantageous if a projection in the arcuate second wall is arranged substantially at the level of the center of a projection in the flat first wall. As a result, a favorable pipe design is created because the pipe constrictions are not arranged by the projections at the same height, which limits the pressure drop increase.

It is also expedient if at least one end region or preferably both end regions of the flat tube is or are formed without projections. This improves the boiling prevention in the tube of the heat exchanger. It is expedient if the end regions have a length of about 5 mm to 50 mm, these end regions for the various projections can be different lengths. Preferably 15 mm without any kind of projections and another 30 mm without protrusions are carried out to the outside.

It is also advantageous if at least one end region or preferably both end regions of the flat tube is or are formed without projections. This is particularly advantageous because winglets, nubs and dents do not start and / or end at the same longitudinal coordinate of the pipe.

The object of the present invention with respect to the heat exchanger is achieved by a heat exchanger with the features of claim 16.

Advantageous developments of the present invention are described in the subclaims and the following description of the figures.

Brief description of the drawings

Fig.1a

eine schematische Ansicht eines Flachrohrs in einer Ansicht von oben,

Fig.1b

eine schematische Ansicht eines Flachrohrs in einer Ansicht von der Seite,

Fig.1c

eine schematische Ansicht eines Flachrohrs in einer Ansicht von unten,

Fig.1d

eine schematische Ansicht eines Flachrohrs in einer Ansicht von vorn,

Fig.1e

eine schematische Ansicht eines Flachrohrs in einer perspektivischen Ansicht,

Fig.2a

eine schematische Ansicht eines Flachrohrs in einer Ansicht von oben,

Fig.2b

eine schematische Ansicht eines Flachrohrs in einer Ansicht von vorn,

Fig.2c

eine schematische Ansicht eines Flachrohrs in einer perspektivischen Ansicht,

Fig.3a

eine schematische Ansicht eines Ausschnitts eines Flachrohrs in einer Ansicht von oben,

Fig.3b

eine schematische Ansicht eines Ausschnitts eines Flachrohrs in einer Ansicht von unten,

Fig.3c

eine schematische Ansicht eines Vorsprungs in einer bogenförmigen Wandung.

In the following the invention with reference to an embodiment with reference to a drawing will be explained in detail. In the drawing shows:

1a

a schematic view of a flat tube in a view from above,

1b shows

a schematic view of a flat tube in a view from the side,

Figure 1C

a schematic view of a flat tube in a view from below,

Fig.1d

a schematic view of a flat tube in a front view,

1E

a schematic view of a flat tube in a perspective view,

2a

a schematic view of a flat tube in a view from above,

2b

a schematic view of a flat tube in a front view,

Figure 2c

a schematic view of a flat tube in a perspective view,

3a

a schematic view of a section of a flat tube in a view from above,

3b

a schematic view of a section of a flat tube in a view from below,

3 c

a schematic view of a projection in an arcuate wall.

Preferred embodiment of the invention

The FIGS. 1a to 1e show an embodiment of a flat round flat tube 1, which has two opposite flat first walls 2, 3. The two flat first walls 2, 3 are substantially flat and arranged parallel to each other. The flat first walls 2, 3 are connected to each other by means of arcuate second walls 4, 5 on the longitudinal side of the flat first walls 2, 3. The arcuate second walls 4, 5 are semicircular or otherwise arcuate, formed.

The flat tube defines between the substantially flat first walls 2, 3 and the arcuate second walls 4, 5 an inner space 6 for the flow through the flat tube by means of a medium. The medium is preferably exhaust gas or an exhaust gas-air mixture. The flat tube is advantageously used as a tube of an exhaust gas cooler or intercooler.

As can be seen, in the flat first walls 2, 3 projections 7 are impressed, which protrude into the interior 6 of the flat tube 1 in order to achieve there a turbulence of the flowing through the flat tube 1 medium.

The projections 7 are stamped as elongated projections 7 in the flat first wall 2, 3. The projections 7 are, as in the FIGS. 1a to 1e to recognize, x-shaped and O-shaped arranged in the opposite walls 2, 3 impressed, with the x-shaped indentations 8 alternate with the o-shaped indentations 9 viewed in the longitudinal direction of the flat tube 1.

An o-shaped arrangement of projections means that four of the projections are arranged diamond-shaped, so that they form a quasi O. An x-shaped arrangement of projections means that four of the projections are arranged x- or star-shaped, so that they form an X virtually.

Furthermore, in the walls 2, 3 outwardly directed projections 10 are provided which can serve as spacers of adjacent flat tubes 1, wherein the outwardly projecting projections 10 are arranged in the region of the o-shaped projections. The projections are arranged in the center of four o-shaped projections 7.

In comparison of the FIGS. 1 a and 1c it can be seen that the arrangement of the projections 7 on a wall 2 in relation to the arrangement of the projections 7 on the opposite wall 3 is offset from one another. Thus, with an x-shaped arrangement 8 of the projections 7 on the wall 2 opposite to the wall 3, an o-shaped arrangement 9 of the projections 7 and vice versa. The arrangement of the outwardly projecting projections 10 is offset between opposite first walls 2, 3 to each other.

Furthermore, it can be seen that in the arcuate second wall 4, 5 projections 11 are provided which protrude from the arcuate second wall 4, 5 in the interior 6 of the flat tube 1.

In the embodiment of FIGS. 1a to 1e the periodicity of the projections 7 is plotted with the Wiederhollänge L, wherein the periodicity of the projections 11 is denoted by the Wiederhollänge I. The repeat length is the length after which the same pattern is repeated. The repeat length I is in the characters 1a to 1e half the repetition length L, so that the repetition rate of the projections 11 is twice as high as the repetition rate of the projections 7.

In the FIGS. 1a to 1e It can be seen that the projections 11 are arranged opposite one another in both arcuate second walls 4, 5. Alternatively, the projections 11 of an arcuate wall 4 could also be arranged offset to the projections 11 of the opposite wall 5.

The FIGS. 2a to 2c show a further embodiment of a flat tube 21 according to the invention, which as well as the embodiment of FIGS. 1a to 1e has substantially flat first walls 22, 23 which are opposite and which are arranged parallel to each other. The first walls 22, 23 are formed by second arcuate walls 24, 25 connected to each other. In this case, projections, such as indentations, 27, 28 are provided in the flat first walls, which protrude from the first walls 22, 23. In this case, the projections 27 protrude into the interior 26 and the projections 28 protrude outward.

In the arcuate second walls 24, 25 projections 29 are also provided, which protrude into the interior 26. The arrangement of the projections 27, 28 substantially corresponds to the arrangement of the projections 7, 10 of the FIGS. 1 a to 1e, wherein the arrangement of the projections 29 substantially the arrangement of the projections 11 of FIGS. 1a to 1e equivalent. The difference between the embodiment of FIGS. 2a to 2c to the embodiment of the FIGS. 1 a to 1e is that the repetition length I 'in the embodiment of the FIGS. 2a to 2c the repeat length L of the projections 27 corresponds.

The FIGS. 3a and 3b show the arrangement of a projection 29 in relation to the arrangement of the projections 27. It can be seen that the center 30 of the projection 29 is approximately at the same height as the center 31 of a projection 27. The projection 29 is thus centered to a projection 27th that with a group of protrusions 27 is arranged in an O-shape, wherein in the center of the O-shaped arrangement, a projection 28 is arranged.

The Figure 3c shows the extension of a projection 29 by way of example, wherein the dimension transverse to the longitudinal direction of the flat tube, the embossing depth is about 1.0 mm and the embossing radii and the outlet radii are each about 6.0 mm. The embossing depth of the projections 29 can usefully be selected in the range between 0.5 mm and 1.2 mm in order to protrude sufficiently deep into the interior relative to the arcuate second wall. The impression is formed by a central embossing radius with two peripheral radii. The length, transverse to the embossing depth, can advantageously amount to several times the embossing depth.

In the FIGS. 3b and 3a It can be seen that the projections 27 are arranged at an angle of approximately 22 ° to the longitudinal axis of the tube, wherein the projections 28 are round or oval, wherein in the case of an oval shape the longitudinal axis is arranged parallel to the longitudinal axis of the tube.

Claims (15)

1. A flat tube (1) having two opposing, substantially flat first walls (2, 3) arranged parallel to one another, and two curved second walls (4, 5) connecting the two flat first walls (2, 3), with an interior space (6) through which a medium can flow, wherein projections (7) protruding into the interior space (6) are provided in at least one of the flat first walls (2, 3), wherein at least one, preferably both of the two opposing, flat first walls (2, 3) have outward-facing projections (10), characterised in that projections (11) protruding into the interior space (6) are provided in the curved second walls (4, 5).
2. The flat tube as claimed in claim 1, characterised in that both of the opposing, flat first walls (2, 3) each have projections (7) protruding into the interior space (6).
3. The flat tube as claimed in one of the preceding claims, characterised in that both of the opposing, curved second walls (4, 5) have projections (11) protruding into the interior space (6).
4. The flat tubes as claimed in one of the preceding claims, characterised in that the inward-facing projections (7) of the flat first walls (2, 3) are arranged with a first repeat rate along the longitudinal axis of the flat tube.
5. The flat tubes as claimed in one of the preceding claims, characterised in that the inward-facing projections (11) of the curved second walls (4, 5) are arranged with a second repeat rate along the longitudinal axis of the flat tube.
6. The flat tube as claimed in claim 5, characterised in that the one repeat rate substantially corresponds to a whole-number multiple of the other repeat rate.
7. The flat tube as claimed in claim 5, characterised in that the second repeat rate is twice the first repeat rate.
8. The flat tube as claimed in one of the preceding claims, characterised in that the projections (7) of the flat first walls protruding into the interior space are arranged in an x-shape (8) and/or o-shape (9).
9. The flat tube as claimed in one of the preceding claims, characterised in that the outwardly protruding projections (10) of the flat walls (2, 3) are arranged between the projections of the first wall arranged in an o-shape and protruding into the interior space.
10. The flat tube as claimed in claim 8 or 9, characterised in that the projections (7) of opposing first walls (2, 3) protruding into the interior space (6) are arranged so as to complement one another, so that an x-shaped arrangement in a first wall is situated opposite an o-shaped arrangement of an opposing first wall.
11. The flat tube as claimed in at least one of the preceding claims, characterised in that the projections provided in the curved second walls (4, 5) and protruding into the interior space have an oval cross section.
12. The flat tube as claimed in one of the preceding claims, characterised in that a projection (11) in the curved second wall (4, 5) is arranged substantially on a level with the centre of a projection (7) in the flat first wall (2, 3).
13. The flat tube as claimed in one of the preceding claims, characterised in that at least one end area or preferably both end areas of the flat tube (1) is/are formed without projections.
14. The flat tube as claimed in claim 13, characterised in that the recessed end areas for the respective projections may deviate from one another.
15. A heat exchanger having a plurality of flat tubes, wherein the flat tubes are formed having the features of at least one of the preceding claims.

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