FIELD OF THE INVENTION

The present invention relates to a heat exchanger comprising a number of heat exchanger plates provided with a pressed pattern of depressions and elevations, said depressions and elevations being adapted to contact depressions and elevations of neighbouring plates when the plates are stacked in a stack to form the heat exchanger, such that interplate flow channels are formed between the plates, wherein the interplate flow channels are in selective fluid communication with port openings placed near the corners of the heat exchanger plates, the selective communication being arranged by providing the areas surrounding the port openings on different heights, such that the areas surrounding the port openings of neighbouring heat exchanger plates contact one another when no communication between the interplate channel limited by the neighbouring plates is desired, whereas the areas surrounding the port openings of neighbouring heat exchanger plates do not contact one another when fluid

communication between the port opening and the interplate channel between the neighbouring plates is desired, the heat exchanger further comprising a start plate provided with a pressed pattern comprising depressions and elevations adapted to contact the depressions and elevations of a neighbouring heat exchanger plate such that an interplate flow channel is formed between the start plate and the neighbouring heat exchanger plate.

PRIOR ART

In the art of brazed heat exchangers, there has for long time been a growing need for fastening of external piping, e.g. so-called hydro blocks, to the heat exchanger. By such fastening of the internal piping, special connections that must be

metallurgically bonded to the heat exchanger may be omitted.

One way of providing fastening means for external piping is known, wherein one or several "ears" extending in a plane of a start or end plate of a brazed plate heat exchanger are arranged at short ends of the start plate. Providing ears at the short ends is a fairly easy process - all you have to do is to take a portion of the "skirt" that normally circumferes the start or end plate and bend it such that forms an ear; due to the design of the heat exchanger plate that neighbors the start or end plate, there will not be any sealing problem for the flow channel that is formed between the start or end plate and its neighbouring heat exchanger plate.

If the ears are to be provided elsewhere around the circumference of the start plate, e.g. along the long sides of the start plate, provision of fastening ears is far more complicated. At the long sides, the pressed pattern providing for the flow channels between the start or end plate and the neighbouring heat exchanger plate will make a sealing very difficult.

In the art, there are several examples of heat exchangers having an external plate fastened to an outer heat exchanger plate. The external plate may be provided with ears for fastening of the heat exchanger to e.g. a wall or for enabling attachment of fastening means for external piping. Such external plates are however costly and they provide no heat exchange. Examples of external plates having fastening means are disclosed in e.g. SE-B-532,084 (corresponding to WO2008/1403901A1),

WO2015/150321 and WO2008/034812.

It is the object of the present invention to provide a heat exchanger that allows fastening ears to be provided at any position along the circumference of the start or end plate while the start or end plate has an active role in the heat exchange.

SUMMARY OF THE INVENTION

The present solves, or at least alleviates, the above and other problems by providing a heat exchanger comprising fastening ears extending outside the start plate and parallel to a plane of the start plate, said fastening ears being provided in the vicinity of a sealing between the start plate and its neighbouring heat exchanger plate.

In one embodiment of the invention, the sealing may comprise a skirt extending around the circumference of the start plate and nearly perpendicular to a plane thereof and being arranged to contact a corresponding skirt of the neighbouring heat exchanger plate. This embodiment is beneficial in that no "dead" flow zones are formed in the interplate flow channel between the start plate and the neighbouring heat exchanger plate. In another embodiment of the invention, the sealing is formed by a contact between a surface of a heat exchanger plate, said surface extending generally in the plane of the heat exchanger plate and a corresponding surface of the start plate. This embodiment is beneficial since the fastening ear will be located at the same plane as the plane of the start plate.

The fastening ears may comprise a flat surface, said flat surface being surrounded by a secondary skirt, said skirt being provided basically perpendicular to a plane of the flat surface. The secondary skirt will increase the strength of the fastening ear.

The start plate, the heat exchanger plates and an end plate may be joined to one another by brazing.

In order to increase the strength of the heat exchanger, the start plate and/or the end plate may be made from a thicker gauge material than the heat exchanger plates.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described by means of examples of preferred embodiments with reference to the appended drawings, wherein:

Fig. 1 is a section view of a heat exchanger according to a first embodiment of the present invention, the section being taken along a plane running along the line A-A of Fig. 2;

Fig. 2 is a top view of the heat exchanger depicted in Fig. 1 ;

Fig. 3 a is an exploded assembly view of a heat exchanger according to the first embodiment of the invention;

Fig. 3b is a perspective view showing a start plate comprised in the heat exchanger according to the first embodiment of the invention.

Fig. 4 is a section view of a heat exchanger according to a second embodiment of the present invention, the section being taken along a plane running along the line A- A of Fig. 5;

Fig. 5 is a top view of the heat exchanger depicted in Fig. 4; Fig. 6 is an exploded assembly view of a heat exchanger according to the second embodiment of the invention;

Fig. 7 is a perspective view of a heat exchanger plate comprised in the heat exchanger according to the second embodiment of the invention;

Fig. 8 is a perspective view of a start plate comprised in the heat exchanger according to the present invention;

Fig. 9 is a section view of a heat exchanger according to a third embodiment of the present invention, the section being taken along a plane running along the line A-A of Fig. 10;

Fig. 10 is a top view of the heat exchanger depicted in Fig. 9;

Fig. 1 1 is an exploded assembly view of a heat exchanger according to the third embodiment of the invention;

Fig. 12 is a perspective view of a start plate comprised in the heat exchanger according to the third embodiment of the invention;

Fig. 13 is a section view of a heat exchanger according to a fourth embodiment of the present invention, the section being taken along a plane running along the line A- A of Fig. 2;

Fig. 14 is a top view of the heat exchanger depicted in Fig. 13;

Fig. 15 is an exploded assembly view of a heat exchanger according to the first embodiment of the invention;

Fig. 16 is a section view of a heat exchanger according to a fifth embodiment of the present invention, the section being taken along a plane running along the line A- A of Fig. 14;

Fig. 17 is a top view of the heat exchanger depicted in Fig. 16;

Fig. 18 is an exploded assembly view of a heat exchanger according to the fifth embodiment of the invention;

Fig. 19 is a section view of a heat exchanger according to a sixth embodiment of the present invention, the section being taken along a plane running along the line A- A of Fig. 16;

Fig. 20 is a top view of the heat exchanger depicted in Figs. 18-19; and Fig. 21 is an exploded assembly view of a heat exchanger according to the third embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

With reference to Figs. l-3b, a heat exchanger 100 according to a first embodiment of the invention is shown. The heat exchanger 100 comprises a number of heat exchanger plates 1 10a, each of which being provided with a pressed pattern adapted to keep the plates on a distance from one another under formation of interplate flow channels when the heat exchanger plates are stacked in a stack to form a heat exchanger. The flow channels are in selective fluid communication with port openings 100a, 100b, 100c and lOOd, wherein the selective flow is achieved by providing the port openings at different heights. At one end of the stack of heat exchanger plates 1 10a, an end plate 110b is provided. The end plate 1 10b is similar to the heat exchanger plates 1 10a, but is not provided with port openings. It may also be thicker than the heat exchanger plates 110a. In order to seal the flow channels, circumferential skirts 1 15a, 1 15b are provided along the edge of each heat exchanger plate and the end plate 1 10b, respectively, wherein the skirts of neighbouring plates are designed to contact one another once the heat exchanger plates 1 10a have been stacked to form the heat exchanger 100.

At the other end of the stack of heat exchanger plates 110a, a start plate 120 is provided. This start plate is also similar to the heat exchanger plates, however with some exceptions:

i. the port openings of the start plate are surrounded by areas located at the same level;

ii. fastening ears 130 are provided along a skirt 140.

The fastening ear 140 may be attached anywhere along the circumference of start plate 120. In the shown example of Figs. l-3b, the fastening ears are provided at the long sides of the start plate, but it is also possible to provide the ears at the short sides. Each fastening ear 130 is located such that a top surface 150 thereof is parallel to the plane of the start plate 120. The top surface 150 connects to the skirt 140 and is consequently placed on a level differing from the level of the start plate 120. Moreover, the top surface connects to a secondary skirt 160 that surrounds the top surface. The secondary skirt 160 also connects to the skirt 140. A hole 170 is provided in the top surface 150 and serves for allowing e.g. a screw or the like to extend therethrough in order to serve as a fastening means.

According to this embodiment, it is crucial that the skirt 140 extends from the plane of the start plate 120 sufficiently to allow the skirt 140 to seal against the skirt 1 15a of the neighbouring heat exchanger plate 1 10a, even where the fastening ear 130 is provided. It is also beneficial if the skirt 140 of the start plate 120 fits snugly to the entire height of its neighbouring skirt 1 15a where the fastening ears are not provided, since this will give a support for the secondary skirt 160 when there is a load on the fastening ear 130.

As implied above, the main reason for providing the secondary skirt 160 around the top surface 150 is to increase the strength thereof. A flat surface is not very well suited for taking a load applied perpendicular to its plane, but by the provision of the secondary skirt 160 and its snug connection to the skirt 1 15a of its neighbouring heat exchanger plate a load applied perpendicular to the plane of the top surface 150 will be transferred efficiently there between.

As mentioned, the heat exchanger plates, the start plate and the end plate are placed in a stack to form the plate heat exchanger 100. In order to join the plates together, a brazing material, e.g. copper, nickel or any alloy having a melting point lower than the material of the heat exchanger plates, the start plate and the end plate is placed between the plates. Thereafter, the stack of plates and brazing material is placed in a furnace, and the temperature is increased such that the brazing material melts. Then, the temperature is lowered such that the brazing material solidifies, hence joining the plates to one another.

Another embodiment of the invention is shown in Figs. 4-8. According to this embodiment, a heat exchanger 200 comprises a number of heat exchanger plates 210a, each of which being provided with a pressed pattern adapted to keep the plates on a distance from one another under formation of interplate flow channels when the heat exchanger plates 210a are stacked in a stack to form a heat exchanger. The flow channels are in selective fluid communication with port openings 200a, 200b, 200c and 200d, wherein the selective flow is achieved by providing the port openings at different heights. At one end of the stack of heat exchanger plates 210a, an end plate 210b is provided. The end plate 210b is similar to the heat exchanger plates 210a, but is not provided with port openings. It may also be thicker than the heat exchanger plates 210a. In order to seal the flow channels, circumferential skirts 215a, 215b are provided along the edge of each heat exchanger plate 210a and the end plate 1 10b, respectively, wherein the skirts of neighbouring plates are designed to contact one another once the heat exchanger plates 210a have been stacked to form the heat exchanger 200.

At the other end of the stack of heat exchanger plates 210a, a start plate 220 is provided. This start plate is also similar to the heat exchanger plates, however with some exceptions:

i. the port openings of the start plate are surrounded by areas located at the same level;

ii. fastening ears 230 are provided along a circumference of the start plate.

The fastening ear 240 may be attached anywhere along the circumference of start plate 220. In the shown example of Figs. 4-8, the fastening ears are provided at the long sides of the start plate 220, but it is also possible to provide the ears at the short sides.

Each fastening ear 230 is located such that a top surface 250 thereof is parallel to, and in level with, the plane of the start plate 220. The top surface 250 connects to a plane of the start plate 220. Moreover, the top surface connects to a secondary skirt 260 that surrounds the top surface 250. The secondary skirt 260 also connects to the skirt 240. A hole 270 is provided in the top surface 250 and serves for allowing e.g. a screw or the like to extend therethrough in order to serve as a fastening means.

According to this embodiment, the sealing of the flow channel formed between the start plate 220 and its neighbouring heat exchanger plate 210a is not solely provided by contacting the skirt 240 of the start plate 210 with the skirt 215a of the neighbouring heat exchanger plate 210a. Instead, the heat exchanger plates 210a are provided with flat portions 280, which are arranged to form a seal by contacting corresponding portions 290 located in the vicinity of the fastening ears 230 of the start plate 220. This embodiment is beneficial in that the plane of the top surface 250 will be level with the plane of the start plate 220.

Also for the second embodiment, the heat exchanger plates, the start plate and the end plate are placed in a stack to form the plate heat exchanger 200. In order to join the plates together, a brazing material, e.g. copper, nickel or any alloy having a melting point lower than the material of the heat exchanger plates, the start plate and the end plate is placed between the plates. Thereafter, the stack of plates and brazing material is placed in a furnace, and the temperature is increased such that the brazing material melts. Then, the temperature is lowered such that the brazing material solidifies, hence joining the plates to one another.

With reference to figs. 9-12, a heat exchanger 300 according to a third embodiment of the invention is shown. The heat exchanger 300 comprises a number of heat exchanger plates 310a, each of which being provided with a pressed pattern adapted to keep the plates on a distance from one another under formation of interplate flow channels when the heat exchanger plates are stacked in a stack to form a heat exchanger. The flow channels are in selective fluid communication with port openings 300a, 300b, 300c and 300d, wherein the selective flow is achieved by providing the port openings at different heights. At one end of the stack of heat exchanger plates 310a, an end plate 310b is provided. The end plate 310b is similar to the heat exchanger plates 310a, but is not provided with port openings. It may also be thicker than the heat exchanger plates 310a. In order to seal the interplate flow channels, circumferential skirts 315a, 315b are provided along the edge of each heat exchanger plates 310a and the end plate 310b, respectively, wherein the skirts of neighbouring plates are designed to contact one another once the heat exchanger plates 310a have been stacked to form the heat exchanger 300.

At the other end of the stack of heat exchanger plates 310a, a start plate 320 is provided. This start plate is also similar to the heat exchanger plates, however with some exceptions: i. the port openings of the start plate are surrounded by areas located at the same level;

ii. fastening ears 330 are provided along a skirt 340, which extends along the circumference of the start plate 320 and is adapted to seal the interplate flow channel formed between the start plate and its neighbouring heat exchanger plate 310a.

The fastening ear 340 may be attached anywhere along the circumference of start plate 320. In the shown example of Figs. 9-12, the fastening ears are provided at the long sides of the start plate 320, but it is also possible to provide the ears at the short sides.

Each fastening ear 330 is located such that a top surface 350 thereof is parallel to the plane of the start plate 120, and level therewith, i.e. provided at the same height. The top surface 350 connects to the skirt 340 by a recessed portion 380, hence allowing the skirt 340 to seal against the skirt of a neighbouring heat exchanger plate 310a. Moreover, the top surface connects to a secondary skirt 360 that surrounds the top surface. The secondary skirt 360 also connects to the skirt 340. A hole 370 is provided in the top surface 350 and serves for allowing e.g. a screw or the like to extend therethrough in order to serve as a fastening means.

The recessed portion 380 is located between the plane of the start plate 380 and the plane surface 350. One wall connecting to the recessed portion is actually the skirt 340, and a wall opposite thereto connects the recessed portion 380 and the flat surface 350. By the provision of the recessed portion, it is possible to achieve a fastening ear located at the same level as the plane of the start plate 320, while the sealing of the flow channel formed between the start plate 320 and its neighbouring heat exchanger plate 310a is achieved by contact between the skirt 340 of the start plate 320 and the skirt 315a of the neighbouring heat exchanger plate 310a.

According to this embodiment, just like for the first embodiment, it is crucial that the skirt 340 extends from the plane of the start plate 320 sufficiently to allow the skirt 340 to seal against the skirt 315a of the neighbouring heat exchanger plate 310a, even where the fastening ear 330 is provided.

As implied above, the main reason for providing the secondary skirt 360 around the top surface 350 is to increase the strength thereof. A flat surface is not very well suited for taking a load applied perpendicular to its plane, but by the provision of the secondary skirt 360 and its snug connection to the skirt 315a of its neighbouring heat exchanger plate a load applied perpendicular to the plane of the top surface 350. With reference to Figs. 13-15, a heat exchanger 400 according to a fourth embodiment of the invention is shown. The heat exchanger 400 comprises a number of heat exchanger plates 410a, each of which being provided with a pressed pattern adapted to keep the plates on a distance from one another under formation of interplate flow channels when the heat exchanger plates are stacked in a stack to form a heat exchanger. The flow channels are in selective fluid communication with port openings 400a, 400b, 400c and 400d, wherein the selective flow is achieved by providing the port openings at different heights. At one end of the stack of heat exchanger plates 410a, an end plate 410b is provided. The end plate 410b is similar to the heat exchanger plates 410a, but is not provided with port openings. It may also be thicker than the heat exchanger plates 110a. In order to seal the flow channels, circumferential skirts 415a, 415b are provided along the edge of each heat exchanger plates and the end plate 410b, respectively, wherein the skirts of neighbouring plates are designed to contact one another once the heat exchanger plates 410a have been stacked to form the heat exchanger 400.

At the other end of the stack of heat exchanger plates 410a, a start plate 420 is provided. This start plate is also similar to the heat exchanger plates, however with some exceptions:

i. the port openings of the start plate are surrounded by areas located at the same level;

ii. fastening ears 430 are provided along a circumferential skirt 440.

The fastening ear 440 may be attached anywhere along the circumference of start plate 420. In the shown example of Figs. 13-15, two fastening ears 430 are provided opposite one another at the long sides of the start plate 420, whereas one ear

430 is provided at the short side.

Each fastening ear 430 is located such that a top surface 450 thereof is parallel and flush to the plane of the start plate 420. Moreover, the top surface connects to a secondary skirt 460 that extends along sides of top surface. The secondary skirt 460 also connects to the skirt 440 and provides thereby strength to the ear 430.

According to this embodiment, the sealing of the flow channel formed between the start plate 420 and its neighbouring heat exchanger plate 410a is not solely provided by contacting the skirt 440 of the start plate 410 with the skirt 415a of the neighbouring heat exchanger plate 410a. Instead, at least the heat exchanger plate 410a that neighbor the start plate 420 is provided with a flat portion 480, which extends inside the skirt 440 in the plane of the start plate. Inside the ears 430, i.e. towards a centre of the start plate 420, a flat surface 490 is provided. This flat surface 490 and the flat portion 480 will form a seal sealing the flow channel formed between the start plate 420 and its neighbouring heat exchanger plate 410a. This embodiment is beneficial in that the plane of the top surface 450 will be level with the plane of the start plate 420 and in that the ears 430 may be provided anywhere along the circumference of the start plate.

As implied above, the main reason for providing the secondary skirt 460 along the sides of the top surface 450 is to increase the strength thereof. A flat surface is not very well suited for taking a load applied perpendicular to its plane, but by the provision of the secondary skirt 460 and its snug connection to the skirt 415a of its neighbouring heat exchanger plate, a load applied perpendicular to the plane of the top surface 450 will be transferred efficiently there between.

As mentioned, the heat exchanger plates, the start plate and the end plate are placed in a stack to form the plate heat exchanger 400. In order to join the plates together, a brazing material, e.g. copper, nickel or any alloy having a melting point lower than the material of the heat exchanger plates, the start plate and the end plate is placed between the plates. Thereafter, the stack of plates and brazing material is placed in a furnace, and the temperature is increased such that the brazing material melts. Then, the temperature is lowered such that the brazing material solidifies, hence joining the plates to one another.

A fifth embodiment of the invention is shown in Figs. 16-19. According to this embodiment, a heat exchanger 500 comprises a number of heat exchanger plates 510a, each of which being provided with a pressed pattern adapted to keep the plates on a distance from one another under formation of interplate flow channels when the heat exchanger plates 510a are stacked in a stack to form a heat exchanger. The flow channels are in selective fluid communication with port openings 500a, 500b, 500c and 500d, wherein the selective flow is achieved by providing the port openings at different heights. At one end of the stack of heat exchanger plates 510a, an end plate 510b is provided. The end plate 510b is similar to the heat exchanger plates 510a, but is not provided with port openings. It may also be thicker than the heat exchanger plates 510a. In order to seal the flow channels, circumferential skirts 515a, 515b are provided along the edge of each heat exchanger plate 510a and the end plate 510b, respectively, wherein the skirts of neighbouring plates are designed to contact one another once the heat exchanger plates 510a have been stacked to form the heat exchanger 500.

At the other end of the stack of heat exchanger plates 510a, a start plate 520 is provided. This start plate is also similar to the heat exchanger plates, however with some exceptions:

i. the port openings of the start plate are surrounded by areas located at the same level;

ii. fastening ears 530 are provided along a circumference of the start plate. The fastening ear 530 may be attached anywhere along the circumference of start plate 520. In the shown example of Figs. 4-8, the fastening ears are provided at the long sides of the start plate 520, such that a line crossing the centers of the port openings 500a, 500b and 500c, 500d, respectively, will run through the fastening ears 530.

Each fastening ear 530 is located such that a top surface 550 thereof is parallel to, and in level with, the plane of the start plate 520. The top surface 550 connects to a plane of the start plate 520. Moreover, the top surface connects to a secondary skirt 560 that extends along the sides of the top surface 550. The secondary skirt 560 also connects to the skirt 540.

According to this embodiment, the sealing of the flow channel formed between the start plate 520 and its neighbouring heat exchanger plate 510a is not solely provided by contacting the skirt 540 of the start plate 510 with the skirt 515a of the neighbouring heat exchanger plate 510a. Instead, at least the heat exchanger plate 510a that neighbour the start plate 520 is provided with a flat portion 580, which extends inside the skirt 540 in the plane of the start plate and in the vicinity of the port openings in the vicinity of which the ears 530 are provided. Inside the ears 530, i.e. towards a centre of the start plate 520, a flat surface 590 is provided. This flat surface 590 and the flat portion 580 will form a seal sealing the flow channel formed between the start plate 520 and its neighbouring heat exchanger plate 510a. This embodiment is beneficial in that the plane of the top surface 450 will be level with the plane of the start plate 520 and in that the ears 530 may be provided anywhere along the circumference of the start plate.

Also for the fifth embodiment, the heat exchanger plates, the start plate and the end plate are placed in a stack to form the plate heat exchanger 500. In order to join the plates together, a brazing material, e.g. copper, nickel or any alloy having a melting point lower than the material of the heat exchanger plates, the start plate and the end plate is placed between the plates. Thereafter, the stack of plates and brazing material is placed in a furnace, and the temperature is increased such that the brazing material melts. Then, the temperature is lowered such that the brazing material solidifies, hence joining the plates to one another.

With reference to Figs. 19-21, a heat exchanger 600 according to a sixth embodiment of the invention is shown. The heat exchanger 600 comprises a number of heat exchanger plates 610a, each of which being provided with a pressed pattern adapted to keep the plates on a distance from one another under formation of interplate flow channels when the heat exchanger plates are stacked in a stack to form a heat exchanger. The flow channels are in selective fluid communication with port openings 600a, 600b, 600c and 600d, wherein the selective flow is achieved by providing the port openings at different heights. At one end of the stack of heat exchanger plates 610a, an end plate 610b is provided. The end plate 610b is similar to the heat exchanger plates 610a, but is not provided with port openings. It may also be thicker than the heat exchanger plates 610a. In order to seal the interplate flow channels, circumferential skirts 615a, 615b are provided along the edge of each heat exchanger plates 610a and the end plate 610b, respectively, wherein the skirts of neighbouring plates are designed to contact one another once the heat exchanger plates 610a have been stacked to form the heat exchanger 600. At the other end of the stack of heat exchanger plates 610a, a start plate 620 is provided. This start plate is also similar to the heat exchanger plates, however with some exceptions:

i. the port openings of the start plate are surrounded by areas located at the same level;

ii. fastening ears 630 are provided along a skirt 640, which extends along the circumference of the start plate 620 and is adapted to seal the interplate flow channel formed between the start plate and its neighbouring heat exchanger plate 610a.

The fastening ears 640 may be attached anywhere along the circumference of start plate 620. In the shown example of Figs. 7-9, the fastening ears are provided near corners between the long sides and short sides of the start plate 620.

Each fastening ears 630 are located such that a top surface 350 thereof is parallel to the plane of the start plate 620, and level therewith, i.e. provided at the same height.

As can be seen in Figs. 19-21, the skirt 640 that surrounds and seals most of the circumferential connection between the start plate 620 and its neighbouring heat exchanger plate 610a continues to form a skirt 660 that reinforces the ear 630. This will give an as large ear as possible.

Just like in the fourth and fifth embodiments, the circumferential portions not sealed by cooperation between the skirt 515a and the skirt 640 of the start plate and its neighbouring heat exchanger plate are provided by contact between a flat portion 690 in the vicinity (i.e. inside) the ears 630 of the start plate 620 and a flat portion 680 provided at least on the heat exchanger plate neighbouring the start plate.

A common feature of all the shown embodiments is that the fastening ears 430; 530; 630 are so short that they can be arranged without the need for extra material, i.e. they have a size being equal to the size of the circumferential skirt 440; 540; 640. This provides for cost savings, since the start plates may be manufactured from a piece of sheet material being rectangular. Prior art fastening ears have all required extensions from the basic rectangular shape, hence making for inefficient material use.

As mentioned, the heat exchanger plates, the start plate and the end plate are placed in a stack to form the plate heat exchanger 300. In order to join the plates together, a brazing material, e.g. copper, nickel or any alloy having a melting point lower than the material of the heat exchanger plates, the start plate and the end plate is placed between the plates. Thereafter, the stack of plates and brazing material is placed in a furnace, and the temperature is increased such that the brazing material melts. Then, the temperature is lowered such that the brazing material solidifies, hence joining the plates to one another.