EP2631585A2

EP2631585A2 - Heat exchanger, heat exchanger plate, and method for producing a heat exchanger

Info

Publication number: EP2631585A2
Application number: EP13000055.7A
Authority: EP
Inventors: Lars Persson
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 2012-01-23
Filing date: 2013-01-08
Publication date: 2013-08-28
Anticipated expiration: 2033-01-08
Also published as: ES2698099T3; RU2523080C1; RU2013102013A; EP2631585A3; CN103217031B; CN103217031A; EP2631585B1

Abstract

A heat exchanger is provided comprising a plurality of pairs of heat exchanger plates (1a) formed of sheet metal having a three-dimensional structured pattern, a first flow path being defined within the plurality of said pairs and a second flow path being defined between said pairs, each plate (1a) having at least one through-opening.

It is intended to have a solid connection between adjacent heat exchanger plates (1a, 1b, 1c) in the area of the through-opening.

To this end said through-opening is surrounded by tongues (10, 12, 13) cut from the area of the through-opening and bend out, wherein the tongues (10, 12) of one plate (1a, 1b) are inserted into the through-opening of a neighbouring plate (1b, 1c).

Description

The invention relates to a heat exchanger comprising a plurality of pairs of heat exchanger plates formed of sheet metal having a three-dimensional structured pattern, a first flow path being defined within the plurality of said pairs and a second flow path being defined between said pairs, each plate having at least one through-opening.
Furthermore, the invention relates to a heat exchanger plate formed of sheet metal having a three-dimensional structured pattern, and having at least one through-opening.
The invention relates as well to a method for producing a heat exchanger forming a stack of pairs of heat exchanger plates formed of sheet metal having a three-dimensional structured pattern, each plate having at least one through-opening.
A heat exchanger of the kind mentioned above is known from US 2007/0261829 A1 . The heat exchanger plates of this heat exchanger have a three-dimensional structured pattern comprising bulges and hollows. The bulges and hollows are placed against respective hollows and bulges of an adjacent heat exchanger plate to form the flow path on the primary and on the secondary side of the heat exchanger.
Other kinds of heat exchanger plates comprise a kind of herringbone pattern.
A heat exchanger requires four connections, i.e. two pairs of connections. One pair of connections is necessary for the primary side, i.e. a supply connection and a return connection. The other pair of connections is necessary for the secondary side, i.e. for receiving and returning the fluid which should be heated or cooled with the help of the heat exchanger.
In many cases the connections are made with help of through going bores which are briefly termed as "through-openings". These through-openings are provided in the corners of the heat exchanger plates. A heat exchanger formed of a stack of plates needs to be formed in a manner where the inlet and outlet channels defined by the through-openings are strong enough to sustain even substantially high pressures of the fluids. In particular in connection with dimple heat exchangers of the kind described in US 2007/0261829 A1 the channels have to withstand rather high pressures.
In known heat exchangers, neighbouring heat exchanger plates have been connected in the area of the through-openings by means of a number of weldings surrounding the through-openings. However, it is difficult to make such a connection sufficiently strong to withstand the high pressure.
The task underlying the invention is to have a solid connection between adjacent heat exchanger plates in the area of the through-opening.
This task is solved in that said through-opening is surrounded by tongues cut from the area of the through-opening and bent out, wherein the tongues of one plate are inserted into the through-opening of a neighbouring plate.
The material which has to be removed for forming the through-opening is no longer wasted. It is used to form a wall surrounding the through-opening and consisting of separate tongues. When the tongues of one plate are inserted into the through-opening of the neighbouring plate a sort of cylinder is formed extending through the through-openings, thus forming a stable channel in the opening area to withstand rather high pressures.
In a preferred embodiment said tongues have a length, said length being at least twice a distance between neighbouring plates. In this way the tongues of neighbouring plates can overlap each other over a rather long distance which can be used to make a connection between neighbouring plates stable enough.
In a preferred embodiment said tongues of a plate are connected to the tongues of a neighbouring plate. Such a connection can be made by welding for example. The tongues of the plates form a chain holding the heat exchanger plates together even when the pressure between the plates is rather high. Another possibility would be to braze the tongues together.
Preferably the tongues of neighbouring plates form connecting areas, wherein adjacent connecting areas are separated from each other. This makes it simple to form the connection between neighbouring tongues. In each connecting area only two tongues are connected so that it is rather simple to form the connection and to check the connection.
Preferably the tongues have a triangular form. This makes it simple to produce the tongues by cutting lines running diametrically through the through-opening. When for example four cutting lines are used eight tongues are produced which can be bent perpendicular to the plane of the heat exchanger plate.
Preferably said tongues of neighbouring plates have the same angular position with respect to said through-bore. When the heat exchanger plates are assembled to form a stack each tongue overlaps a tongue arranged at the same angular position of an adjacent plate. This leads to a maximum overlapping area between the tongues of adjacent plates.
Preferably an endplate is provided having a bulge adapted to receive tongues of at least a heat exchanger plate next to said endplate. In a system having a stack of heat exchanger plates with bent down tongues there could arise a problem at the bottom plate, where there is no neighbouring plate. One solution is to provide said endplate with a bulge which is adapted to receive the bent down tongues of at least a heat exchanger plate next to said endplate. In this case the heat exchanger plate next to the endplate can have the same shape as all the other heat exchanger plates of the heat exchanger. Preferably the bulge is adapted to receive the tongues not only of the heat exchanger plate next to said endplate but also the tongues of at least the second heat exchanger plate counted from the endplate.
Preferably said bulge has a depth, said depth being larger than a hight of said tongues perpendicular to said heat exchanger plate next to said endplate. In this case the tongues can remain in their upright state, i.e. it is not necessary to deform the tongues. In any case, the tongues can be connected to the wall of the bulge.
In an alternative embodiment tongues of a heat exchanger plate next to an endplate are, at least at their tip, bent parallel to said endplate. These tongues are bent at least twice comprising a first section almost perpendicular to the plane of the heat exchanger plate and further comprising a second section parallel to the plane of the endplate.
In this case it is preferred that the tongues of at least two heat exchanger plates next to said endplate form, at least at their tips, a layered structure on an internal surface of said endplate. This layered structure can easily be connected to said endplate.
The task is solved with a heat exchanger plate of the kind mentioned above in that said through-opening is surrounded by tongues cut from the area of the through-opening and bent out.
For the production of the heat exchanger plate it is in most cases necessary to shape the plate in a press. This press can be used to cut the tongues and to bend them out, e.g. almost perpendicular to the plane of the plate. These tongues make it easy to assemble the plate to form a stack of plates since the tongues can be used as auxiliary means to align the plates.
Preferably the tongues have a triangular form. In this case cut lines can be used running along the diameter of the through-bore. This is a simple way to produce the tongues.
The task is solved by a method for producing a heat exchanger as mentioned above in that said through-opening is formed by cutting the sheet material in the area of the through-opening to form tongues and bending out said tongues.
In this way the tongues can be used to facilitate the assembling of the stack of heat exchanger plate. The tongues can be used to connect the heat exchanger plates in the area of the through-openings.
Preferably the tongues of a plate are inserted into the through-opening of a neighbouring plate. This means that the tongues of one plate overlap the tongues of neighbouring plates over a predetermined distance. This overlapping area gives a rather stable and pressure proofed connection between neighbouring heat exchanger plates.
Preferably the tongues of a plate are connected to the tongues of the neighbouring plate. The connection between the tongue is able to withstand the tensile forces produced by the pressures inside the heat exchanger.
A preferred example of the invention will now be described in more detail with reference of the drawing, wherein:

Fig. 1: is a plane view of a heat exchanger plate,
Fig. 2: is an enlarged view of the upper right corner of the heat exchanger plate of Fig. 1,
Fig. 3: is a view of an arrangement of a plurality of plates before bending out tongues,
Fig. 4: is a view of an arrangement of a plurality of plates each having tongues,
Fig. 5: shows an example of another form of tongues,
Fig. 6: shows an example of connection of the tongues with a bottom plate and
Fig. 7: shows an alternative to the embodiment of Fig. 6.

Fig. 1 shows a heat exchanger plate 1 as it is shown in US 2007/0261829 A1 . This plate 1 comprises bulges 2 which are raised by a given height over the plane of the heat exchanger plate 1. Furthermore, the heat exchanger plate 1 comprises hollows 3 which are sunk to a given depth in this heat exchanger plate 1. The bulges 2 are symbolized by white circles while the hollows 3 are symbolized by circles with a cross. As it is described in US 2007/0261829 A1 two such plates 1 form a pair of plates, in which one heat exchanger plate 1 is rotated about 180° about its longer edge 4. A plurality of such pairs is stacked one above the other. A first flow path is formed within these pairs and a second flow path is formed between these pairs.
The heat exchanger plate 1 is made of sheet metal. A sheet metal is a material having a good thermal conductivity and can be formed in a press or die. It is also possible to use plastic materials as sheet metal. The bulges 2 and the hollows 3 form a three-dimensional structured profile. This profile is produced in a press or die.
The heat exchanger plate 1 comprises four through-openings 5-8. These through-openings 5-8 are used to form channels or connections. For example the through- openings 5, 7 form a supply and return for the first flow path and the through- openings 6, 8 form a supply and a return for the second fluid path.
In Fig. 1, 2 and 3 the through-openings 5-8 are still closed.
Fig. 2 - 4 shows a way to open the through-openings 5-8.
Fig. 3 and 4 show a stack of three heat exchanger plates 1a, 1b, 1c.
In a first step four diametrically running cuts are made in the area of the through-opening 5. The four cut lines 9 are shown in Fig. 2. When the cuts have been produced the area of the through-opening 5 is covered by eight tongues 10. Each tongue has an almost triangular form.
In a next step the tongues 10 are bent out of the plane of each heat exchanger plate 1a, 1b, 1c so that the tongues 10 are arranged almost perpendicular to the plane 11 of the heat exchanger plate 1. This is schematically shown in Fig. 3 and 4. The bending does not produce a sharp edge but a rounded transition between the plane 11 and the tongue 10. The cutting and bending of the tongues 10 is preferably performed before the heat exchanger plates 1a, 1b, 1c are stacked.
When the plurality of heat exchanger plates 1a, 1b, 1c are arranged one above the other in order to form a stack, the tongue 10 of heat exchanger plate 1a overlaps a tongue 12 of the adjacent heat exchanger plate 1b. This tongue 12 overlaps a tongue 13 of the next adjacent heat exchanger plate 1c.
Tongues 10, 12 form an overlapping area 14, in which the tongues 10, 12 can be connected, e.g. by welding. Tongues 12, 13 form an overlapping area 15 in which the tongues 12, 13 can be connected, e.g. by welding as well.
As it comes out from Fig. 4 the overlapping area 14, 15 (which can be referred to as connecting area as well) are separated from each other, i.e. in each overlapping area 14, 15 only two tongues 10, 12 or 12, 13, respectively, overlap each other.
The tongues 10, 12, 13 have a length which is at least twice a distance 16 between neighbouring or adjacent heat exchanger plates 1a, 1b. This makes the overlapping area 14, 15 large enough.
The tongues 10, 12, 13 of all heat exchanger plates 1a, 1b, 1c have the same angular orientation with respect to the through-opening 5. In this way the tip of a tongue 10, 12 always overlaps with a base of the next tongue 12, 13. In this way a very reliable connection between the tongues can be established.
If necessary, such a connection can be made for all of the through-openings 5-8.
Sealing means (not shown) can be arranged around the tongues between neighbouring heat exchanger plates 1a, 1b, 1c since the connection of the tongues 10, 12, 13 is not necessarily tight per se.
Since the connection between neighbouring plates 1a, 1b, 1c is rather strong, there is no need for special top or bottom plates in a heat exchanger formed by the heat exchanger plate 1 described. This means that all heat exchanger plates 1 can have the same form and thickness.
The three-dimensional structured pattern can have a form different of that shown in Fig. 1. For example, the pattern can be a herringbone pattern as it is known in the art.
Fig. 5 illustrates an alternative version of how the tongues 10 may be shaped. In this case a star 17 is cut out of the through-opening 5 forming five tongues 10 each having a triangular form. However, any other imaginable shape would also apply to the present invention, such as more rounded tongues 10.
Having a system with bent down tongues 10 gives a problem at an endplate, for example a bottom plate 18 where there is no neighbouring plate.
Fig. 6 shows a first solution to this problem, where the bottom plate 18 has a bulge 19 adapted to receive the bent down tongues 10 of a heat exchanger plate 1d next to the endplate 18. It can be seen that the bulge 19 has a depth which is larger than a height of the tongues 10 perpendicular to the plane of the heat exchanger plate 1d next to the endplate 18. In this case it is possible that the tongues 10 are fully inserted into the bulge 19 without a necessity for deforming the tongues 10.
The bulge 19 not only receives the tongues 10 of the heat exchanger plate 1d next to the endplate 18, but also the tongues of the second heat exchanger plate 1e counted from the endplate 18. The tongues of these two heat exchanger plates 1d, 1e can be connected to the internal wall of the bulge 19. However, it is possible to insert even more tongues into the bulge 19, i.e. the tongues of more heat exchanger plates 1d, 1e ....
Another possibility is shown in Fig. 7. In this case an endplate 20 is used having a plane internal surface 21. The tongues 10 of the heat exchanger plates 1d, 1e next to the endplate 20 are further bent forming sections 22 running parallel to the internal surface 21 of said endplate 20. These tongues form a layered structure on the internal surface 21 of said endplate 20.
One may say the tongues 10 are formed by cutting in a direction with a vector having a component in the radial direction towards the centre of the respective opening 5-8 being different from zero. The angular component of the vector, this being tangential to the circumference of the opening, may be zero or different from zero.
Forming tongues 10 and connecting them as described offers forms so to speak a tube-like structure that extends through the depth of the heat exchanger. This gives a strong structure in the areas of the openings 5-8. If instead the openings 5-8 were flanged in a manner where the rim of the openings 5-8 are bend down without cutting with vector component in the radial direction different from zero, the formed tube would also form a sealing for fluid access into the spaces between the heat exchanger plates, thus openings would have to be formed. By forming the tongues 10 with a radial vector component in the cuts, material will be removed from the opening, as also illustrated in Fig. 5 (Fig. 3 shows the situation where the angular vector component is zero), and then such openings will be formed naturally when connecting the bend down tongues 10, where their sizes will depend on the relative radial vector component to the angular vector component.

Claims

Heat exchanger comprising a plurality of pairs of heat exchanger plates (1) formed of sheet metal having a three-dimensional structured pattern (2, 3), a first flow path being defined within the plurality of said pairs and a second flow path being defined between said pairs, each plate (1) having at least one through-opening (5-8), characterized in that said through-opening (5-8) is surrounded by tongues (10, 12, 13) cut from the area of the through-opening (5-8) and bent out, wherein the tongues (10, 12, 13) of one plate (1) are inserted into the through-opening of a neighbouring plate (1b) and where the tongues (10) are cut with an radial vector component different from zero.
Heat exchanger according to claim 1, characterized in that said tongues (10, 12, 13) have a length, said length being at least twice a distance (16) between neighbouring plates (1a, 1b).
Heat exchanger according to claim 1 or 2, characterized in that said tongues (10, 12) of a plate (1a, 1b) are connected to the tongues (12, 13) of a neighbouring plate (1b, 1c).
Heat exchanger according to claim 3, characterized in that the tongues (10, 12; 12, 13) of neighbouring plates (1a, 1b; 1b, 1c) form connecting areas (14, 15), wherein adjacent connecting areas (14, 15) are separated from each other.
Heat exchanger according to any of claims 1 to 4, characterized in that the tongues (10, 12, 13) have a triangular form.
Heat exchanger according to any of claims 1 to 5, characterized in that said tongues (10, 12, 13) of neighbouring plates have the same angular position with respect to said through-opening (5-8).
The heat exchanger according to any of claims 1 to 6, characterized in that an endplate (18) is provided having a bulge (19) adapted to receive tongues (10) of at least a heat exchanger plate (1d) next to said endplate (18).
The heat exchanger according to claim 7, characterized in that said bulge (19) has a depth, said depth being larger than a hight of said tongues (10) perpendicular to said heat exchanger plate (1d) next to said endplate (18).
The heat exchanger according to any of claims 1 to 6, characterized in that tongues (10) of a heat exchanger plate (1d) next to an endplate (20) are, at least at their tip, bent parallel to said endplate (20).
The heat exchanger according to claim 9, characterized in that the tongues (10) of at least two heat exchanger plates (1d, 1e) next to said endplate (20) form, at least at their tips, a layered structure on an internal surface (21) of said endplate (20).
Heat exchanger plate (1) formed of sheet metal having a three-dimensional structured pattern (2, 3) and having at least one through-opening, characterized in that said through-opening (5-8) is surrounded by tongues (10, 12, 13) cut from the area of the through-opening (5-8) and bent out.
Heat exchanger plate according to claim 11, characterized in that said tongues (10, 12, 13) have a triangular form.
Method for producing a heat exchanger forming a stack of pairs of heat exchanger plates (1) formed of sheet metal having a three-dimensional structured pattern (2, 3), each plate (1) having at least one through-opening (5-8), characterized in that said through-opening (5-8) is formed by cutting the sheet metal in the area of the through-opening (5-8) to form tongues (10, 12, 13) and bending out said tongues (10, 12, 13).
Method according to claim 13, characterized in that tongues (10, 12) of a plate (1a, 1b) are inserted into the through-opening of a neighbouring plate (1b, 1c).
The method according to claim 14, characterized in that the tongues (10, 12) of a plate (1a, 1b) are connected to the tongues (12, 13) of the neighbouring plate (1b, 1c).