EP2618093A2

EP2618093A2 - Heat exchanger, heat exchanger plate, and method for producing a heat exchanger

Info

Publication number: EP2618093A2
Application number: EP20130000073
Authority: EP
Inventors: Lars Persson
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 2012-01-23
Filing date: 2013-01-09
Publication date: 2013-07-24
Also published as: RU2013102010A; EP2618093A3; RU2529957C1; CN103225973B; CN103225973A

Abstract

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

It is intended to facilitate the connection of the heat exchanger to external fluid lines.

To this end the through-opening of at least said endplate (1a) comprises a raised edge forming a flange (10).

Description

The invention relates to a heat exchanger comprising a stack of 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 said pairs and a second flow path being defined between said pairs, each plate having at least one through-opening, an outermost plate being an endplate.
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, an outermost plate being an endplate.
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 patterns can be used. Another known pattern is a herringbone pattern.
A heat exchanger usually requires four ports, i.e. two pairs of ports. One pair of ports is necessary for the primary side, i.e. a supply port and a return port. The other pair of ports is necessary for the secondary side, i.e. for supplying and returning the fluid which should be heated or cooled with the help of the heat exchanger. The ports have to be connected with external fluid lines. The ports are usually arranged in line with the respective through-openings. In order to establish a connection between the external fluid lines and the heat exchanger special top and bottom plates are necessary making the heat exchanger expensive to manufacture. In the following then top and bottom plates are briefly referred to as "endplates".
The task underlying the invention is to facilitate the connection of the heat exchanger to external fluid lines.
This task is solved in said the through-opening of said endplate comprises a raised edge forming a flange.
This flange can be used for the connection with the external fluid line. The flange forms a cylinder or a short tube making it easy to fix a fluid line directly or to fix a tap where the tap may comprise the connection means needed like a threading or the like. The flange is an integral part of the heat exchanger plate. It is formed of the material pressed out of the area in which the through-opening is arranged. Up to now the through-opening has been formed by stamping or cutting out the through-opening. The cut out material has been wasted. Now the material is kept integral with the heat exchanger plate and it is used to form the flange. The through-opening and the raised edge forming the flange can be made in the same press or die in which the bulges and hollows are produced, i.e. simply by pressing a plate of sheet material into the desired shape.
Preferably said flange is directed outwardly from the stack. In this case there is a short tube protruding outwardly from the stack of heat exchanger plates. This short tube or cylinder can easily be used to fix a tap comprising the needed connection means or to fix directly an external fluid line.
Preferably at least a neighbouring plate to said endplate comprises at least one through-opening having a raised edge forming a flange, said flange being inserted into the flange of said endplate. This second flange, i.e. the flange of the plate next to the endplate makes the port even more stable since it bears against the inside of the flange of the endplate at least over a part of its length.
Preferably said flanges of said plates are connected to each other. The connection between the flanges can be made by welding or brazing. Such a connection makes the port more stable.
Preferably a transition zone between such flange and the plane of the plate is rounded and the flange of a plate contacts a flange of a neighbouring plate beyond the transition zone. When the transition zone is rounded the stress in the plate is minimized. When the contact between the flanges of two neighbouring or adjacent plates is made out of the rounded transition zone it is clear that a contact between the flanges takes place in a region in which both flanges have a cylinder or slightly conical form. Such a contact zone facilitates the connection between the two flanges.
Preferably the through-opening of all plates are provided with a raised edge forming a flange, each of the flanges being connected to a flange of a neighbouring plate. When all plates are connected by means of the flanges there is an additional means for enhancing the pressure resistance of the heat exchanger so that fluids having a higher pressure can be used. A fluid with an elevated pressure tries to "blow up" the space between two heat exchanger plates. This is prevented by the connection between the flanges of two neighbouring or adjacent plates. The pressure produces a tensile stress in the flange bridging the space between the two adjacent plates. However, since the flange is made of sheet metal it can withstand these tensile stresses so that a blow up of the heat exchanger is prevented.
The task is solved with a heat exchanger plate of the kind mentioned above in that said through-opening has a raised edge forming a flange.
As mentioned above the flange is an integral part of the heat exchanger plate. It can be formed in the same die or press as the pattern. The material in the area of the through-opening is no longer removed but pressed into the form of the flange. This flange can be used for several purposes. One purpose is to provide a part of a connection port when the flange is part of an endplate, i.e. of a top plate or a bottom plate of the stack of heat exchanger plates. Another purpose is the connection of neighbouring or adjacent heat exchanger plates.
Preferably a transition zone between the plane of the plate and the flange is rounded. Such a rounded transition zone minimizes stresses in the sheet metal so that the risk of damage is minimized.
The task is solved by a method for producing a heat exchanger as mentioned above in that said through-opening of said endplate is formed with a raised edge by pressing the sheet metal of the area of the through-opening into a flange forming said raised edge.
The flange of the endplate can be used to fix directly or indirectly an external fluid line so that a top or bottom plate can be made simpler in construction.
Preferably the endplate is fixed to the stack with the flange being directed outwardly. In this way a part of a connection port is produced forming a short tube or cylinder protruding outwardly so that it is easy to fix a tap or a fluid line directly.
In a preferred embodiment a neighbouring plate to the endplate is formed with a flange surrounding the through-opening and this flange is inserted into the flange of the endplate. This makes the connecting port more stable.
Preferably the flange of the endplate and the flange of its neighbouring plates are connected. The two flanges can, for example, be welded or brazed. Such a connection makes the port even more stable.
A preferred embodiment of the invention will now be described in more detail with reference to the drawing wherein:

Fig. 1: is a plan view of a heat exchanger plate,
Fig. 2: is a section through a stack of heat exchanger plates,
Fig. 3: is a perspective view of a through-opening,
Fig. 4: is a schematic sectional view of an arrangement of a plurality of heat exchanger plates in the region of the through-opening,
Fig. 5: is a schematic sectional view of an alternative embodiment of Fig. 4,
Fig. 6: is a schematic illustration showing bulging of heat exchanger plates and
Fig. 7: shows a schematic sectional view of a plurality of heat exchanger plates connected in the region of the through-opening.

Fig. 1 shows a heat exchanger plate 1a as it is shown in US 2007/0261829 A1 . This plate 1a comprises bulges 2 which are raised by a given height over the plane of the heat exchanger plate 1a. Furthermore, the heat exchanger plate 1a comprises hollows 3 which are sunk to a given depth in this heat exchanger plate 1a. 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 heat exchanger plates 1a form a pair of plates in which one heat exchanger plate 1a is rotated by 180° about its longer edge 4. A plurality of such pairs is stacked one above the other. A first flow path is formed within the pairs and a second flow path is formed between these pairs.
Adjacent or neighbouring heat exchanger plates 1a are connected such that the bulges 2 of a lower heat exchanger plate are welded to the bulges of the reversed (rotated by 180° about the longer edge 4) upper heat exchanger plates. The hollows 3 of the lower heat exchanger plate are welded to the hollows 3 of a reversed (rotated about its longer edge 4 by 180°) heat exchanger plate. Such hollows 3 form bulges 2 of the reversed heat exchanger plate. This is schematically illustrated in Fig. 2. In this figure (the same is true for all other figures) the number of plates and the sizes of hollows and bulges are not representative for a real system. To simplify the further description, the bulges 2 and the hollows 3 are commonly termed as "dimples".
Heat exchanger plates are stacked in a manner, where the dimple bottoms 15 of an upper plate are aligned to dimple tops 14 of a lower plate, and here the plates are welded together by means of weldings 16, thus forming strong connections due to the dense distribution of dimples throughout the heat exchanger.
The heat exchanger plate 1a comprises four through-openings 5-8. These through-openings 5-8 are used to form channels or connections through which the fluids are supplied and returned to the respective spaces within the pairs of heat exchanger plates or between the pairs of heat exchanger pairs. For example, the through- openings 5, 7 forms a supply and a return for the first flow path and the through- openings 6, 8 form a supply and a return for the second fluid path.
The heat exchanger plate 1 is formed of a sheet metal. A sheet metal is a material having a good thermal conductivity. Furthermore, the material can be shaped by means of a press or die. Such a material will in most cases be in fact a metal. However, other materials having the abilities can be used as well, like some plastic materials.
The bulges 2 and the hollows 3 form a three-dimensional structured profile or pattern. This pattern is produced in a press or die. Other patterns can be used as well, e.g. a herringbone pattern.
When a plurality of heat exchanger plates 1a is stacked and forms a heat exchanger it is necessary to connect external fluid lines to the port which in turn are connected to the through-openings 5-8.
Referring to Fig. 2, a rim portion forms an identical level to one of the top dimples 14 or bottom dimples 15, i.e. to the bulges 2 and hollows 3. Thus, when the plates are stacked, every second connections are "opening" dimple 13 to "opening" dimple 13, forming fluid connection to the spaces in between the respective two plates, and every other second connections are directly rim portion 17 to rim portion 17, excluding fluid connection to the spaces in between the respective two plates. In this manner two separate sealed flow systems are created.
As can be seen from Fig. 2, two endplates are provided, i.e. a top plate 1a and a bottom plate 1e. These endplates 1a, 1e are substantially thicker and of more rigid material to protect the heat exchanger plates as it is well known in the art.
Fig. 2 illustrates the two flow paths, i.e. the primary path P and the secondary path S. As can be seen the two flow paths are separated. Fig. 2 illustrates an opening 6 having excess only to the primary flow path P and an opening 8 having excess only to the secondary flow path S.
The through-openings 5-8 have to be connected to respective lines supplying and returning fluids to the primary and secondary flow paths.
Fig. 3 and 4 illustrate a first aspect of the present invention, where, rather than just forming a through-opening in the respective top plate 1a (or bottom plate 1e) the through-opening 5 is formed with a raised edge 9 forming a flange 10. The flange 10 is made integral with the rest of the top plate 1a. The flange 10 is made of the material which has been pressed out of the heat exchanger plate 1a to form the through-opening 5. When the through-opening 5 is formed no material is wasted.
Taps 13 may be fixed to the flanges 10 in any manner known in the art, where the taps 13 may comprise the needed connection means like windings etc. The flanges 10 thus form a stable platform for the attachment of the tab 13 of the top plate 1a.
In this manner a cost efficient heat exchanger may be formed, where the tabs 13 or other connection means can be welded to the heat exchanger after brazing, addressing customer demands.
Fig. 5 illustrates an alternative solution, where the tab 13 is positioned inside the flange 10.
As illustrated in Fig. 6, heat exchanger plates, 1b, 1c, 1d..., are formed with bended edges 23 overlapping and welded together, thus internal flow systems are sealed from the external flow systems. As seen in Fig. 2, cavities 22 exist in the area of the opening 8 inside the heat exchanger forming weak points with no support, resulting in a "bulging" heat exchanger seen in Fig. 6. The plates 1b, 1c, 1d... are well welded, but the top plate 1a (the same is true for the bottom plate 1e) as mentioned previously have been found not easily to form fluid tight weldings to the heat exchanger plates. A solution to overcome this problem is shown in Fig. 7.
Fig. 7 shows a situation in which a top plate 1a and a plurality of heat exchanger plates 1b, 1c, 1d are stacked one above the other. The top plate 1a and each plate 1b, 1c, 1d is provided with a flange 10, 11, 12. The flange 10 of the top plate 1a is directed outwardly, i.e. it extends almost perpendicular to the plane of the outermost heat exchanger plate 1a.
The flange 11 of the heat exchanger plate 1b next to the top plate 1a is inserted into the flange 10 of top plate 1a. Furthermore, the flange 11 is connected to the flange 10. Such a connection can be established by welding, brazing or the like. Furthermore, a corresponding flange 12 of the heat exchanger plate 1c next to the second heat exchanger plate 1b is inserted into the flange 11 of the second heat exchanger plate 1b and connected to the flange 11. The three flanges 10, 11, 12 form a kind of cylinder or tube which is rather stable. This solves the problem of the "bulging" heat exchanger plates 1a, 1b, 1c etc., as illustrated in Fig. 7, in that this cylinder or tube forms a supporting 'pillar' extending through the heat exchanger. Openings would naturally have to be formed in all those of the flanges 12 where fluidic access from the openings 5, 6, 7, 8 are to be formed to the flow channels between plates 1c and 1d etc.
Fig. 8 illustrates one example of how such openings may be formed quite naturally in these flanges 12 by cutting tongues 30 in the area of the openings 5-8, e.g. prior to forming the flanges. Then, when overlapping these tongues 30, forming the flanges 12, in the manner as also illustrated in Fig. 7, such openings naturally will occur.
The tongues 30 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.
By forming the tongues 30 with a radial vector component in the cuts, material will be removed 31 from the opening, as also illustrated in Fig. 8, and this will increase the sizes of these openings into the channels of the heat exchanger, thus giving a design parameter depending on the actual need in relation to flow, pressure etc.
The connection between the flanges 10, 11, 12 has the additional advantage that the heat exchanger plates 1a, 1b, 1c are connected not only in the region of the bulges 2 and hollows 3, but also in the region of the through-opening 5 (the same connection can of course be provided in the region of the other through-openings 6-8).
Looking again at Fig. 2, cavities 25 existing between the top plate 1a and next heat exchanger plate 1b are sealed by a welding 16. However, it has been experienced that such weldings 16 between top plate 1a and heat exchanger plate 1b are not that strong, so there may easily leak undesired fluid into this volume.
This may be solved in a manner as illustrated in Fig. 7 and Fig. 9 in that the flange 11 of the upper plate 1b being next to the top plate 1a are formed without any tongues 30 such that when this flange 11 is connected and possible welded to the flange 10 of the top plate 1a, then this volume will be sealed from the respective opening 5-8.
To even further increase this sealing effect, the flange 10 could optionally be provided with a 'edge' 32 reaching over the end of the flange 11.

Claims

A heat exchanger comprising a stack of a plurality of pairs of heat exchanger plates (1a, 1b, 1c) formed of sheet metal having a three-dimensional structured pattern (2, 3), a first flow path being defined within said pairs and a second flow path being defined between said pairs, each plate (1a, 1b, 1c) having at least one through-opening (5-8), an outermost plate being an endplate (1a), characterized in that the through-opening of said endplate (1a) comprises a raised edge (9) forming a flange (10).
The heat exchanger according to claim 1, characterized in that said flange (10) is directed outwardly from the stack.
The heat exchanger according to claim 2, characterized in that at least a neighbouring plate (1b) to said endplate (1a) comprises at least one through-opening having a raised edge forming a flange (11), said flange (11) being inserted into the flange (10) of said endplate (1a).
The heat exchanger according to claim 3, characterized in that said flanges (10, 11) of said plates (1a, 1b, 1c) are connected to each other.
The heat exchanger according to any of claims 3 to 5, characterized in that a transition zone between said flange (10) and the plane of the plate (1a) is rounded and a flange (10, 11) of a plate (1a, 1b) contacts the flange (11, 12) of a neighbouring plate (1b, 1c) beyond the transition zone.
The heat exchanger according to any of claims 1 to 6, characterized in that the through-opening (5) of all plates (1a, 1b, 1c) are provided with a raised edge forming a flange (10, 11, 12), each flange (10, 11) being connected to a flange (11, 12) of a neighbouring plate.
A heat exchanger plate (1b) formed of sheet metal having a three-dimensional structured pattern (2, 3) and having at least one through-opening (5-8), characterized in that said through-opening (5-8) has a raised edge forming a flange (10).
The heat exchanger plate according to claim 8, characterized in that a transition zone between the plane of the plate (1a) and the flange (10) is rounded.
A method for producing a heat exchanger forming a stack of pairs of heat exchanger plates (1a, 1b, 1c) formed of sheet metal having a three-dimensional structured pattern (2, 3), each plate having at least one through-opening (5-8), an outermost plate being an endplate (1a), characterized in that said through-opening (5-8) of said endplate (1a) is formed with a raised edge by pressing the sheet metal of the area of the through-opening (5-8) into a flange (10) forming said raised edge (9).
The method according to claim 10, characterized in that said endplate (1a) is fixed to the stack with the flange (10) being directed outwardly.
The method according to claims 10 or 11, characterized in that a neighbouring plate (1b) to said endplate (1a) is formed with a flange (11) surrounding the through-opening and this flange (11) is inserted into the flange (10) of said endplate (1a).
The method according to claim 12, characterized in that the flange (10) of said endplate (1a) and the flange of its neighbouring plate (1b) are connected.
The method according to claim 12 or 13, characterized in that a stabilisation ring (14) is positioned between said endplate (1a) and the neighbouring plate (1b), said stabilisation ring (14) surrounding the flange (11) of the neighbouring plate (1b).
The method according to any of claims 10 to 14, characterized in that the through-opening (5) of all plates (1a, 1b, 1c) are formed with a flange (10, 11, 12) and the flange (10, 11) of a plate (1a, 1b) is connected to the flange (11, 12) of a neighbouring plate (1b, 1c).