[0001] 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 the plurality of pairs and a second
flow path being defined between said pairs, each plate having at least one through-opening.
[0002] Furthermore, the invention relates to a heat exchanger plate formed of sheet metal
having a three-dimensional structured pattern.
[0003] The invention relates as well to a method for producing a heat exchanger forming
a stack of heat exchanger plates made of sheet metal having a three-dimensional structured
pattern.
[0004] 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.
[0005] The particular form of the pattern of the heat exchanger plate can be changed. As
an alternative, heat exchanger plates comprising a kind of herringbone pattern can
be used.
[0006] A heat exchanger is used to transfer heat from a fluid on the primary side, i.e.
a fluid flowing through the first flow path, to a fluid on the secondary side, i.e.
to a fluid passing through the second flow path. In many cases at least one of these
fluids has an elevated pressure. The connection between two neighbouring plates must
be strong enough to withstand this pressure. This is usually no problem in an area
where there are enough bulges and hollows. However, in some areas of the plates an
additional connection is necessary.
[0007] The task underlying the invention is to have a solid connection between adjacent
heat exchanger plates.
[0008] This task is solved in that at least one auxiliary opening is provided in said plate,
said auxiliary opening having a raised edge forming a flange, said flange being inserted
into a corresponding auxiliary opening of a neighbouring plate.
[0009] The flanges are integral with the plate. They can easily be formed just by pressing
the sheet metal in the area of the auxiliary opening into the flange. This pressing
can be made simultaneously with the forming of the three-dimensional structured pattern.
The term "sheet metal" covers all materials having a good thermal conductivity and
can be formed in a press or die. It is also possible to use plastic material as sheet
metal.
[0010] In a preferred embodiment the flange of an auxiliary opening of one plate is connected
to the flange of an auxiliary opening of a neighbouring plate. This connection can
be made by welding or brazing. When the flanges are connected in this kind two neighbouring
plates are not only secured against sharing forces but also against forces exerted
by an elevated pressure. Such a pressure usually tends to increase the distance between
two neighbouring plates. Since the flanges can withstand tensile forces it can be
made sure that the distance is not increased.
[0011] Preferably the flanges of a plurality of auxiliary openings form a cylinder and a
stabilisation element is inserted into said cylinder. In this way it is possible to
connect a plurality of plates or even all plates of the stack of heat exchanger plates.
The stabilisation element prevents that a pressure acting between two adjacent plates
compresses the flanges radially which could lead to a weakening of the connection
between two neighbouring plates.
[0012] Preferably at least the outermost flanges are connected to said stabilisation element.
However, all flanges can be connected to said stabilisation element as well. The stabilisation
element can withstand higher tensile forces so that the stack of plates can withstand
higher pressures inside the stack of plates.
[0013] Preferably at least one auxiliary opening is positioned in the vicinity of said through-opening.
In the vicinity of said through-opening there is normally no sufficient connection
between two neighbouring plates. The flange of the auxiliary opening serves for a
connection between two adjacent or neighbouring plates.
[0014] Preferably a transition zone between said flange and said plate is rounded and the
flange of a plate contacts the flange of a neighbouring plate beyond the transition
zone. This means that a connection between two adjacent flanges is made where the
flanges have already a cylindrical form. This makes the connection simple. In the
contact area or overlapping area the two flanges are parallel to each other so that
a reliable connection can be achieved. In the contact area the two flanges can be
parallel to each other.
[0015] Preferably an endplate is provided having a bulge adapted to receive flanges of at
least a heat exchanger plate next to said endplate. In a system having a stack of
heat exchanger plates with raised edges forming flanges 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 flange 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 flange not only
of the heat exchanger plate next to said endplate but also the flange of at least
the second heat exchanger plate counted from the endplate.
[0016] Preferably said bulge has a depth, said depth being larger than a height of said
flange 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 flange. In any case, the flange or flanges can be connected to the wall of the
bulge.
[0017] In an alternative embodiment a flange of a heat exchanger plate next to an endplate
is, at least at it's tip, deformed parallel to said endplate. These flange is deformed
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.
[0018] In this case it is preferred that the flanges 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.
[0019] The task is solved with a heat exchanger plate of the kind mentioned above in that
an auxiliary opening is provided having a raised edge forming an upstanding flange.
[0020] As mentioned above this flange is made integral with the heat exchanger plate. It
can easily be formed by pressing the sheet metal out of the area of the auxiliary
opening to form a raised edge of the auxiliary opening. This raised edge forms a flange
which can be used to connect two adjacent heat exchanger plates to each other. Preferably
a transition zone between said flange and said plate is rounded. A rounded transition
zone prevents weakening of the sheet metal in the area around the auxiliary opening.
[0021] A task is solved by a method for producing a heat exchanger as mentioned above in
that an auxiliary opening having a raised edge is formed in said plates, said raised
edge forming a flange, said flange being inserted in a corresponding auxiliary opening
of a neighbouring plate.
[0022] The flanges can withstand shere forces between neighbouring or adjacent plates. They
produce an increased stability of the stack of plates.
[0023] In a preferred embodiment said flanges are connected to each other. The flanges are
used to prevent that neighbouring plates increase their distance when there is an
elevated pressure between the true plates. In this case the flanges are subjected
to tensile forces. However, since the flanges are made integral with the heat exchanger
plate they are stable enough to withstand these tensile forces generated by the pressure
between two plates.
[0024] Preferably a stabilisation element is inserted through a plurality of auxiliary openings.
This stabilisation element supports the flanges from the inside so that the elevated
pressure cannot compress the flanges in radial direction (related to the auxiliary
opening). Such a radial compression could weaken the connection between flanges of
adjacent plates.
[0025] Preferably said stabilisation element is connected at least to the flanges of the
outermost plates of the stack of heat exchanger plates. When there is an elevated
pressure inside the stack of heat exchanger plates this pressure cannot "blow up"
the stack of heat exchanger plates since the outermost plates are held together by
means of the stabilisation element. In a preferred embodiment all flanges are connected
to the stabilisation element so that even inside the stack of heat exchanger plates
the blowing up due to an elevated pressure can be prevented.
[0026] A preferred example 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 an enlarged view of the upper right corner of the heat exchanger plate of Fig.
1,
- Fig. 3
- is a perspective view of an auxiliary opening,
- Fig. 4
- is a view of an arrangement of a plurality of heat exchanger plates in the region
of an auxiliary opening,
- Fig. 5
- shows an example of connection of flanges with a bottom plate, and
- Fig. 6
- shows an alternative to the embodiment of Fig. 5.
[0027] 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 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 the pairs and a
second flow path is formed between these pairs.
[0028] The heat exchanger plate 1a 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 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.
[0029] The heat exchanger plate 1a is formed of a sheet metal. The term "sheet metal" defines
a material having a good thermal conductivity. Furthermore, the material can be formed
in a press or die. The bulges 2 and the hollows 3 form a three-dimensional structured
profile. This profile is produced in a press or die.
[0030] When a plurality of heat exchanger plates 1a, 1b, 1c (Fig. 4) is stacked one above
the other to form a stack the bulges 2 of a plate 1b is connected to the bulges 2
of the heat exchanger plate 1a which is turned about the edge 4 by 180°. The hollows
3 of plate 1b are connected to the hollows 3 of heat exchanger plate 1c which is also
turned about the edge 4 by 180°. These connections can be made by welding. These connections
are stable enough to withstand the pressure of a fluid between two plates 1a, 1b or
1b, 1c respectively.
[0031] However, in the vicinity of the through-openings 5-8 the connection between two adjacent
plates is not sufficient. In for example a heat exchanger as disclosed in
US 2007/0261829 A1 two adjacent plates are welded with the top surfaces of the bulges 2 of one plate
welded to the top surfaces of the hollows 3 of a adjacent paten. This gives a good
connection of the two plates due to the density of the bulges 2 and hollows 3, meaning
the number of these per square area of the plates.
[0032] In the opening areas 5-8 however, it is common, both in heat exchangers of the kind
as disclosed in
US2007/0261829 or the more common herringbone pattern plate heat exchangers, to encircle the openings
5-8 with bulges and hollows to be welded together, the density of these being limited
by the openings 5-8 themselves and their sizes of being limited in that there needs
to be fluid access into the spaces between the plates. Therefore it is a problem these
areas often are the area of the highest pressures within the heat exchanger.
[0033] As can be seen in Fig. 2 a plurality of auxiliary openings 9 is provided and circling
the through-opening 5. Similar auxiliary openings 9 can be provided around the other
through-openings 6-8.
[0034] The auxiliary openings 9 can be formed in the same press or die which is used to
form the bulges 2 and hollows 3. The auxiliary opening 9 has a raised edge 10 forming
a flange 11, i.e. a wall surrounding the auxiliary opening 9. This flange 11 can be
made of the sheet metal which in the past had to be removed in order to form the auxiliary
opening. The flange 11 stands almost upright with respect to the plane 12 of the heat
exchanger plate 1a.
[0035] Fig. 4 shows the situation coming out, when several plates 1a, 1b, 1c are stacked.
The flange 11 of heat exchanger plate 1a is inserted into the auxiliary opening 9
of the next or adjacent heat exchanger plate 1b contacting the flange 13 of the corresponding
auxiliary opening 9 of heat exchanger plate 1b. The flange 13 of heat exchanger plate
1b is inserted into auxiliary opening 9 of heat exchanger plate 1c contacting the
corresponding flange 14 of its neighbouring heat exchanger plate 1c. The flanges 11,
13, 14 can be welded together forming a sort of "cylinder" reaching through the auxiliary
openings.
[0036] A bolt 15 (or another stabilisation element) is inserted into the cylinder and may
optionally be fixed in the cylinder. In some cases it is sufficient that the bolt
15 is connected to the flanges 11, 14 of the outermost heat exchanger plates 1a, 1c.
In most cases, however, it is preferred that the bolt 15 is connected to all flanges
11, 13, 14.
[0037] As can be seen in Fig. 4 a transition zone between the flange 11, 13, 14 and the
plates 1a, 1b, 1c is rounded and the flange 11, 13 of a plate 1a, 1b contacts the
flange 13, 14 of a neighbouring or adjacent plate 1b, 1c beyond the transition zone.
This has the effect that the flanges contact each other in a cylindrical area.
[0038] Similar auxiliary openings may be distributed over the heat exchanger plate to enhance
strength.
[0039] As described above, the auxiliary openings 9 can be formed in the same tool as the
bulges 2 and hollows 3. However, it is clear that the auxiliary openings 9 together
with the flanges 11, 13, 14 can be formed in a separate tool.
[0040] In the present example the pattern is formed by bulges 2 and hollows 3. However,
it is clear that other forms of pattern can be used, e.g. a herringbone pattern.
[0041] Having a system with raised edges forming flanges 10 around the through-openings
5-8 gives a problem at an endplate, for example a bottom plate 18 where there is no
neighbouring plate.
[0042] Fig. 5 shows a first solution to this problem, where the bottom plate 18 has a bulge
19 adapted to receive the flange 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 hight of the
flange 10 perpendicular to the plane of the heat exchanger plate 1d next to the endplate
18. In this case it is possible that the flange 10 is fully inserted into the bulge
19 without a necessity for deforming the flange 10.
[0043] The bulge 19 not only receives the flange 10 of the heat exchanger plate 1d next
to the endplate 18, but also the flange of the second heat exchanger plate 1e counted
from the endplate 18. The flanges 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 flanges into the bulge 19, i.e. the flanges of more heat exchanger plates
1d, 1e ....
[0044] 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.
1. 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,
a first flow path being defined within the plurality of pairs and a second flow path
being defined between said pairs, each plate having at least one through-opening (5-8),
characterized in that at least one auxiliary opening (9) is provided in said plate (1a, 1b, 1c), said auxiliary
opening (9) having a raised edge (10) forming a flange (11, 13, 14), said flange (11,
13, 14) being inserted in a corresponding auxiliary opening (9) of a neighbouring
plate (1b, 1c).
2. The heat exchanger according to claim 1, characterized in that the flange (11, 13) of an auxiliary opening (9) of one plate (1a, 1b) is connected
to the flange (13, 14) of an auxiliary opening (9) of a neighbouring plate (1b, 1c).
3. The heat exchanger according to claim 1 or 2, characterized in that the flanges (11, 13, 14) of a plurality of auxiliary openings (9) form a cylinder
and a stabilisation element (15) is inserted into said cylinder.
4. The heat exchanger according to claim 3, characterized in that at least the outermost flanges (11, 14) are connected to said stabilisation element
(15).
5. The heat exchanger according to any of claim 1 to 4, characterized in that at least one auxiliary opening (9) is positioned in the vicinity of said through-opening
(5-8).
6. The heat exchanger according to any of claims 1 to 5, characterized in that a transition zone between said flange (11, 13, 14) and said plate (1a, 1b, 1c) is
rounded and the flange (11, 13) of a plate (1a, 1b) contacts the flange (13, 14) of
a neighbouring plate (1b, 1c) beyond the transition zone.
7. 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 flange (10) of
at least a heat exchanger plate (1d) next to said endplate (18).
8. The heat exchanger according to claim 7, characterized in that said bulge (19) has a depth, said depth being larger than a height of said flanges
(10) perpendicular to said heat exchanger plate (1d) next to said endplate (18).
9. The heat exchanger according to any of claims 1 to 6, characterized in that a flange (10) of a heat exchanger plate (1d) next to an endplate (20) is, at least
at it's tip, deformed parallel to said endplate (20).
10. The heat exchanger according to claim 9, characterized in that the flange (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).
11. A heat exchanger plate (1a) formed of a sheet metal having a three-dimensional structured
pattern (2, 3), characterized in that an auxiliary opening (9) is provided having a raised edge (10) forming an upstanding
flange.
12. The heat exchanger plate according to claim 11, characterized in that a transition zone between said flange (11) and said plate (1a) is rounded.
13. A method for producing a heat exchanger forming a stack of heat exchanger plates (1a,
1b, 1c) made of sheet metal having a three-dimensional structured pattern (2, 3),
characterized in that an auxiliary opening (9) having a raised edge (10) is formed in each of said plates,
said raised edge forming a flange, said flange being inserted in a corresponding auxiliary
opening (9) of a neighbouring plate (1b).
14. The method according to claim (13), characterized in that said flanges (11, 13, 14) are connected to each other.
15. The method according to claim 13 or 14, characterized in that a stabilisation element (15) is inserted through a plurality of auxiliary openings
(9).
16. The method according to claim 15, characterized in that said stabilisation element (15) is connected at least to the flanges (11, 13) of
the outermost plates (1a, 1c) of the stack of heat exchanger plates.