EP0134012A2

EP0134012A2 - Profiled tube heat exchanger

Info

Publication number: EP0134012A2
Application number: EP84109338A
Authority: EP
Inventors: Klaus Dipl.-Ing. Hagemeister
Original assignee: MTU Aero Engines GmbH; MTU Motoren und Turbinen Union Muenchen GmbH
Current assignee: MTU Aero Engines GmbH
Priority date: 1983-08-12
Filing date: 1984-08-07
Publication date: 1985-03-13
Also published as: US4577684A; EP0134012A3; DE3329202A1; JPH041279B2; DE3463841D1; EP0134012B1; JPS6078295A

Description

The invention relates to a profile tube heat exchanger according to the preamble of claim 1. Such a heat exchanger is known from GB-OS 2 o43 231 A. However, this publication does not provide any indication of the layer structure of a heat exchanger matrix discussed later. Rather, pre-perforated sheet metal plates are proposed as profile spacers in the present known case, the disadvantages of which are explained in detail below.

- The assembly is very cumbersome, since each profile tube must be inserted in the direction of its longitudinal axis and threaded through the various levels.
- The perforated field in the metal sheets is very difficult to produce.
- The perforated sheets are subject to thermal gradients and the resulting stresses. Since the hole pattern contains narrow material webs, stress concentrations arise at these points with the risk of tearing open, as a result of which the organizing and retaining effect is lost at least locally.
- The basic principle of the free longitudinal displacement of each individual profile pipe causes frictional movements between the pipe surface and the flank of the associated hole in the perforated sheet that holds it laterally. There is therefore a considerable risk that the pipe will be rubbed off in an inadmissible manner at this point.

When the profile tube heat exchanger is exposed to high temperatures, each tube should be able to expand freely in the direction of its longitudinal axis, depending on its individual thermal state, independently of adjacent profile tubes.

As a component of an ordered field of flow-around profiles, each tube is assigned a specific location and position, which it must not leave - in the plane of the cross-section through the field - even under the effect of thermal deformations.

Brackets are required for this purpose.

It has already been proposed to use appropriately perforated sheets which - arranged at different heights - ensure the assignment of the profile tubes.

This construction has several disadvantages of considerable weight:

- The assembly is very cumbersome, since each profile tube must be inserted in the direction of its longitudinal axis and threaded through the different levels.
- The perforated field in the sheets is very difficult to manufacture.
- The level of the perforated sheets is subject to thermal gradients and the resulting stresses. Since the hole pattern contains narrow material webs, stress concentrations arise at these points with the risk of tearing open, as a result of which the ordering and holding effect is lost at least locally.
- The basic principle of the free longitudinal movement of each individual profile tube causes rubbing movements between the tube surface and the side of the associated hole in the perforated plate that holds it to the side. There is therefore a considerable risk that the pipe will be rubbed in an unacceptable manner at this point.

The object of the invention is to provide a heat exchanger with a field of layered profiled connecting pipes, in which the aforementioned disadvantages are overcome and, in particular with a simple construction and simple assembly, the profiled pipes are locally ordered and are supported essentially without tension.
To solve the object of the invention, reference is made primarily to the features of the invention according to the characterizing part of claim 1. Expressed in general terms, it is proposed according to the invention to enclose the profile tubes at predetermined locations with profile strips or sheet metal strips, which by both sides of the profile tube and connected to each other or with the profile tube or in both ways equally so that the profile tube is immovably surrounded by the material of the strips or strips. The spacing by means of sheet metal strips can be carried out in the simplest way by the sheets comprising the profile having a thickness which corresponds to the half of the smallest distance to be bridged between adjacent profile tubes. The contacts arise - depending on the shape of the profile - at points between the tip and the center of the profile tube. The contacting flank sections have a course at these points that lies at an angle to the layer plane. If an individual profile tube is displaced in relation to the rest of the tube field in or against the direction of the layer - for example due to thermal distortions - a wedge effect develops in this embodiment. As a result of this wedge effect, a displacing force acting locally in the plane of the associated layer triggers large cross-reactions which counteract it and have a splitting effect on the locations of the profiles arranged adjacent in the field. With this type of spacing, the regular arrangement of, for example, lancet-shaped profile tubes in the field also represents their closest packing. Any deviation of individual or groups of lancets from their position, for example due to thermal bending, causes expansion via the described wedge effect and elastic displacements of the lancet field.
This effect can be avoided by an advantageous further embodiment of the invention, in that the sheet metal strips enclosing the profile extend in the direction of the external flow around the profile tube from the points on which they meet in pairs, extend further on both sides into the gaps that result in the flow direction from the assignment of the profiles in the field to the next and the previous profile tube. These ends or extensions of the profile or sheet metal strips meet - coming from the respective front profile tube in the flow direction from the respective rear profile tube against the direction of the flow - in the middle of the spaces described above. At the contact points thus created, they are supported against one another in such a way that the profiles standing one behind the other in this direction cannot move out of the position assigned to them in the field. Since there is only a flat contact at these points, but no connection, there is no impediment to the individual longitudinal expansion of the profile tubes or the structure of the profile tube and the profile strip sheath, with the exception of frictional reactions that can occur at the contact points as a result of the holding forces acting there. For better transmission of these holding forces, the contact points can be represented by contact pieces or transmission bodies of the type described above. The contact pieces can be connected to the ends or extensions of the metal strips, either by being enclosed by them or by enclosing them.
It is also possible to use a contact piece which connects the ends of the sheet metal strips to one another at said point between two profile tubes of a layer lying one behind the other in the flow direction, in each case forming an articulated connection point. The connection point can also be designed to be inclusive or inclusive.
At a terminal of the latter alternative be - affects the individual longitudinal expansion of a profile tube or the structure of the profile tube along with profile strips covering over the thus linked with him further profile pipe or structure an angular displacement of the contact piece. The interlinking can be represented by an articulated connection with bushings and bolts, which are made of wear-resistant materials. Links for chain links can also be provided.
Another very advantageous effect of the transmission body or contact pieces comes about if they are dimensioned in width so that they fill the gap between two profile tubes adjacent to the direction of flow. As a result, they also act as distance-keeping elements in this direction. The spacing elements have the function of maintaining the order of the profile tubes in the field. They counteract the tendencies of the profile elements to leave their position due to internal stresses, for example from temperature gradients. As a result of thus induced strain restriction must to the D istanzhaltung guaranteeing bodies forces are transmitted. The system-related and structurally unwanted differential expansion in height direction of the above described Pro - filrohre effect on the space-maintaining friction pads reactions under the action of said holding forces. The relatively slow-running friction movements are superimposed by those resulting from vibrations in the profile field.
In terms of vibration dynamics, the contact points are advantageous attenuators. However, the contacting surfaces are subject to frictional movements. In view of this, it is advantageous that the contact points are formed from additional links - flanks of the profile or metal strips and the contact pieces. On the one hand, the profile tube surfaces are protected against fretting, on the other hand, the contact points can be made resistant to friction by choosing an appropriate material or applying wear-resistant layers.
Of great importance is the fact that the proposed design principle prevents torsional deformations of the profile tubes over the greatest possible distance and therefore the pair of forces resulting from the reaction moment of the support at the contact points is small.
It is also advantageous that the holding forces are transmitted transversely to the direction of flow in the area of the profile crosspieces. Forces that result from the support of the profile tube matrix on surrounding components, for example from mass effects due to impacts and vibrations, can be added up through the profile tube field and propagated as pressure loads over the rigid points of the profile tubes. This applies in a similar way to the force dissipation in the flow direction, in which the rigidity of the field results from the shape of the profile tubes (bending over a long length).
In a further embodiment of the basic idea of the invention, the distance-maintaining contact pieces or transmission bodies can also be provided with fork-shaped approaches be, which, pushed from both sides over the profile tube, embrace the latter and are connected at the joints with the profile tube and also with one another. Alternatively, the joint can be bridged by a pressure piece that absorbs the lateral forces from the transmission bodies.
In a further embodiment, the contact points can also engage in one another in a form-fitting manner, the longitudinal displacement of the profile tube structures being possible.
With regard to the advantageous embodiment of the invention, reference is made to the features according to claims 2 to 16.

1 shows a schematic cross-sectional view of the field of profiled tubes of a profiled tube heat exchanger,
FIG. 2 shows the profile tubes according to FIG. 1 in a partial cross-sectional view in the area of the spacer,
3 shows a profile tube holder of a different configuration of the support elements,
4 shows a profile tube holder according to FIG. 3 with a different configuration of the contact pieces,
5 shows a single profile tube from FIG. 4 with an enclosed contact piece,
F ig. 6 a single profile tube of FIG. 4 with a surrounding contact piece,
7 shows a profile tube holder in the form of a contact piece articulated in the manner of a chain link in a schematic partial cross-sectional view,
8 shows the holder according to FIG. 7 in a top view,
9 shows a schematic cross-sectional view of a further chain-like contact piece between two adjacent profile tubes,
Fig.lo shows a profiled individual tube with fork-shaped transmission bodies,
11 shows the embodiment according to FIG. 1o with pressure pieces arranged in between and
FIG. 12 neighboring profile tubes with a further embodiment of transmission bodies.

The invention is explained in more detail below using an example with reference to the drawing;

show it:;

1 is a schematic cross-sectional view of the field of profiled tubes of a profile tube heat exchanger,
1 in a partial cross-sectional view in the region of the spacer,
3 shows a profile tube holder of a different configuration of the support elements,
4 a profile tube holder according to FIG. 3 with a different configuration of the contact pieces,
5 shows a single profile tube from FIG. 4 with an enclosed contact piece,
F ig. 6 a single profile tube of FIG. 4 with a surrounding contact piece,
7 a profile tube holder in the form of a chain link-like articulated contact piece in a schematic partial cross-sectional view,
8 is a top view of the holder according to FIG. 7,
9 is a schematic cross-sectional view of another chain-like contact piece between two adjacent profile tubes,
Fig. Lo a profiled single tube with fork-shaped transmission bodies,
11 shows the embodiment according to FIG. 1o with intermediate pressure pieces and
12 adjacent profile tubes with a further embodiment of transmission bodies.

1, an arrangement 1 of profile tubes 2 is shown schematically in the area of the flow through the matrix of a profile tube heat exchanger in a partial cross-sectional view. Each profile tube 2 is assigned a specific location and a specific position as part of an ordered profile tube field, which it must not leave in the plane of the cross section through the field according to FIG. 1, even under the effect of thermal deformations.
As illustrated in FIG. 2, profile strips 3, 4, which are connected flat in the form of sheet metal strips, are provided as spacers at predetermined points for a position assignment and holding of the profile tubes 2. 2 each profile tube 2 has a left profile strip 3 and a right profile strip 4, which are essentially the same. Both strips 3, 4 extend essentially in the direction of the hot gas direction A of the profile tube field or the heat exchanger matrix and have the same length, which is longer than that of the tube profile.
The profile strips 3, 4 according to FIG. 2 are dimensioned in such a way that they fill the gaps between the tips of the tubular profiles and the spacing contacts are made at these points. Such a configuration has a simple structure and is easy and inexpensive to manufacture. The forces are transmitted in the area of an oblique contact position between the associated strips ("wedge-shaped support contacts"). All of the profile tubes 2 enclosed in such a flat manner lie next to one another in layers in the overall field of profile tubes according to FIG. 2. The profile tubes 2 or the structures made of profile tube 2 and the associated profile strip sheathing of a layer 1 0 , 11, 12, 13 or 14 shown in the aforementioned manner are linearly adjacent to the layer adjacent to the right and left in the said oblique contact position and are relative in the longitudinal direction of the tube movable relative to each other. The profile strips 3, 4 of a profile tube 2 according to the embodiment of FIG. 2 are firmly connected to one another, so that the enclosed profile tube 2 is immovably enclosed by the material of the strips.
The spacing by means of profile strips or sheet metal strips, which locally encompass the profile tube, can meet higher demands on the accuracy of the positioning, in particular even when there are higher temperature gradients th in the ways shown in Fig. 3 ff. Here, too, the profile tubes 2, which are surrounded by profile strips, lie side by side in layers in the overall field of profile tubes according to FIG. 3. Adjacent profile tubes 2 from adjacent layers are offset from one another in a cross-sectional view, given the same overall longitudinal alignment. The mutual support in the transverse direction takes place through the side surfaces 15, 16 of the profile strip ends 7, 8 each centrally on the outer sides of the profile strips 3, 4 of the adjacent layers which adjoin the right and left. In the longitudinal direction, the mutual support takes place flat on the end faces 17 of the profile strip ends 7, 8. The width spacing of the side surfaces 15, 16 of the profile strip ends 3, 4 is dimensioned according to FIG. 3 so that it crosses the gap between the profile strips 3, 4 two Fills the direction of flow of adjacent profile pipes, which belong to the two adjacent layers on the right and left. The distance required between the profile strip ends 7 and 8 can be represented by stamped-in knobs or, according to FIG. 3, by connecting bodies 18, 19 interposed.
The connecting bodies can also be designed as contact pieces 15 ', 16' according to FIGS. 4 and 5. Both profile strips 3, 4 of each profile tube 2 have mutually parallel, mutually spaced ends, the first (according to FIG. 4 lower) profile strip ends 7 a first contact piece 15 'and the corresponding second profile strip ends 8 on the other side of the same profile tube 2 Take up the corresponding second contact piece 16 '.
The height or width of the contact pieces 15 ', 16' acting as connecting bodies is dimensioned such that they fill the gap between two profile tubes 2 which are adjacent transversely to the direction of flow, the respective side surfaces of the contact pieces 15 ', as can also be seen from FIG. 4. , 16 'have a curved shape according to the adjacent counter surfaces of the profile strips 3, 4. i
The contact pieces 15 ', 16' thus act not only in the flow direction, but also in the transverse direction as spacing elements. The spacing elements have the function of maintaining the order of the profile tubes in the overall field.
The contact pieces 15 ', 16' are supported in an area of the adjacent profile tubes 2, in which they have an inner central crosspiece 9. This ensures good power transmission ratios. 'The arrangement is such that individual profile tubes are longitudinally displaceable with respect to one another due to the effects of heat, without changing the position assignment in the plane of the cross section through the field. Adjacent contact pieces 15 ', 16' lead a relative movement to one another and to adjacent profile strips fen 3, 4 out. In order to minimize frictional wear, at least the outer surfaces of the profile strips 3, 4 can be surface-hardened or provided with a wear-resistant layer.
The exemplary embodiment of a holder for profile tubes 2 illustrated in FIG. 6 comprises connecting bodies 15 "16" which grip the associated profile strip ends, for example 8, in the manner of pliers, in contrast to the exemplary embodiment according to FIG. 5. Furthermore, a contact piece 20 can be used as connecting body between adjacent profile tubes 2 of a layer, which connects the extensions or ends 7, 8 of the profile strips 3, 4 in an articulated manner like a chain link, as shown in FIGS. 7 and 8. The chain link-like contact piece 2o has an articulated bolt connection 21 for each pair of strips. When a terminal or a holder according to the F ig. 7 and 8 cause the individual longitudinal expansion of a profiled tube with respect to the tube thus chained to it causes an angular displacement of the contact piece 2 0 .
The chaining can also be designed as shown in FIG. 9. Here, the articulated movement between bushes 24 and bolts 21, which are made of wear-resistant material. Such a chain link-like contact piece 22 also has two outer plates 22 'and 23.
In a further embodiment of the basic idea of the invention, the distance-maintaining elements can also be formed by transmission bodies or profile strips 5 and 6, which have fork-shaped projections which comprise the profile tube 2 pushed from both sides and at the abutment points, as in FIG
Fig. 1o shown, can be connected to each other by welding.
A joint between the associated fork-shaped parts of the profile strips 5, 6 can also be bridged by pressure pieces 25 according to FIG. 11, which absorb the lateral forces from the profile strips.
In a further embodiment, adjacent fork-shaped profile strips 5, 6 of adjacent profile tubes 2 of a tube layer can be form-fitting, i.e. centering, as shown, for example, in FIG. 12. Longitudinal displaceability in the longitudinal direction of the pipe is also possible here.
Furthermore, the profile strips can be surface-hardened or at least partially provided with a friction-wear-resistant layer.
In training, eg as sheet metal strips, the profile strips can be arranged in a common matrix transverse plane or in several respectively common matrix transverse planes.
4 and 5, it follows that the width h of the contact pieces 15 ', 16' of two profile tubes 2 of a layer 11 is equal to the distance between the left profile strip 3 of the profile tube 2 of a first layer 10 and the right one Profile strip 4 of the associated profile tube 2 of a third layer 12 adjoining it in the transverse direction of the matrix.
Moreover, as already mentioned at the beginning, each profile tube 2 cannot be moved from the profile strips, e.g. 3, 4 (Fig. 4) be enclosed so that the profile strips 3, 4 are longitudinally displaceable together with the respective profile tube 2.

Claims

2. Heat exchanger according to claim 1, characterized in that the individual profile tubes (2) in the longitudinal layer direction over the abutting edges (17) of the abutting profile strip ends (7,8) are supported against each other.

3. Heat exchanger according to claim 1 and 2, characterized in that compliance with the required width dimension for the side surfaces (15, 16) of the profile strip ends (7, 8) of a profile tube (2) by means of connecting bodies (18, 19) inserted between said ends. he follows.

4. Heat exchanger according to claims 1, 2 and 3, characterized in that the profile strip ends (7,8) of adjacent profile tubes (2) of a layer by at least one contact piece (15 ', 16') are loosely or firmly connected to one another.

5. Heat exchanger according to claims 1 to 4, characterized in that at each contact point two contact pieces (15 ', 16') directed towards each other in the longitudinal direction of the layer are provided, which are at least partially enclosed by associated profile strip ends (7, 8) and at their not included, Adjacent end faces widened like a hammer head and axially displaceable in the longitudinal direction of the pipe.

6. Heat exchanger according to claims 1 to 4, characterized in that two contact pieces (15 ", 16") are provided at each contact point in the longitudinal direction of the layer, which at least partially grip around the associated profile strip ends (7,8) like pliers and at their other end faces Adjacent to the surface and axially displaceable in the longitudinal direction of the pipe.

7. Heat exchanger according to claims 1 to 6, characterized in that the contact pieces (20, 22) are articulated like a chain link to associated profile strip ends (7, 8).

8. Heat exchanger according to claims 1 to 7, characterized in that two fork-shaped profile strips (5, 6) are provided for a profile tube (2), of which one (5) has a profile tube side and the other profile strip (6) grips the other side of the profile tube on the left and right side.

9. Heat exchanger according to claims 1 to 8, characterized in that the fork ends directed against the transverse cross-plane of the profile strips (5,6) are firmly connected.

10. A heat exchanger according to claims 1 to 9, characterized in that the fork ends of the profile strips (5, 6) directed against the cross-sectional central plane are connected to one another by pressure pieces (25).

11. Heat exchanger according to claims 1 to 10, characterized in that the one-piece end parts of the profiled strips (5, 6) facing away from the respective fork section (5, 6) of adjacent profiled tubes (2) of a layer - with a mutual interlocking, longitudinally displaceable - interlocking in a form-fitting manner.

12. Heat exchanger according to claims 1 to 11, characterized in that the profile strips (3, 4 or 5, 6) are surface-hardened or at least partially provided with a wear-resistant layer.

13. Heat exchanger according to claims 1 to 12, characterized in that the profile strips (3, 4 or 5, 6) are sheet metal strips which are arranged in a common transverse matrix plane or in several respectively common transverse matrix planes.

14. Heat exchanger according to claims 1 to 13, characterized in that the width (h) of the contact pieces (15 ', 16') of two profile tubes (2) of a layer (11) equal to the distance between the left profile strip (3) of the profile tube (2) a first layer (10) and the right profile strip (4) of the associated profile tube (2) of a third layer (12) adjoining it in the transverse direction of the matrix (see FIG. 4).

15. Heat exchanger according to claims 1 to 14, characterized in that the side surfaces of the contact pieces (15 ', 16') have a curved shape according to the adjacent counter surfaces of the profile strips (3, 4).

16. 'heat exchanger according to claims 1 to 15, characterized in that each profile tube (2) is immovably surrounded by the profile strips (3,4), the profile strips (3,4) together with the respective profile tube (2) are longitudinally displaceable .