EP4607133A1

EP4607133A1 - Method for the assembly of a plate package of a plate heat exchanger and a plate heat exchanger

Info

Publication number: EP4607133A1
Application number: EP24159379.7A
Authority: EP
Inventors: Mattias NORÉN
Original assignee: Alfa Laval Corporate AB
Current assignee: Alfa Laval Corporate AB
Priority date: 2024-02-23
Filing date: 2024-02-23
Publication date: 2025-08-27

Abstract

The present invention relates to a plate heat exchanger (1) comprising a heat exchange plate package (2) comprising vertically packed first heat exchange plates (4, 4') and optionally second heat exchange plates (3) alternatingly arranged between the first heat exchange plates. Each first heat exchange plate comprises a peripheral flank portion (4a, 4b; 4a', 4b') which transitions via a transition area (7a, 7b; 7a', 7b') to a peripheral brim portion (5a, 5b; 5a', 5b'). The flank and brim portions are arranged on two opposing longitudinal sides of each first heat exchange plate. The flank portions of adjacent first heat exchange plates are permanently joined together such that a longitudinally extending flow channel (12) is formed between the adjacent first heat exchange plates. The transition areas and/or brim portions comprise a braze filler recess (71, 73; 52) and/or an angled braze filler receiving surface portion (75; 55) adapted for receiving the braze filler and spreading it to the flank portions. The invention also relates to a method of providing the package.

Description

Technical field

The present invention relates to a plate package of a plate or plate and fin heat exchanger and a method for the assembly of the heat exchanger as defined in the introductory parts of the independent claims attached herein.

Background art

Plate heat exchangers, or PHEs, are heat exchangers which typically comprise a plurality of metallic heat exchange plates arranged in an aligned manner and such that flow channels are formed between the plates. The heat exchange plates are used to separate two fluids and transfer heat between the fluids. In the plate heat exchanger, fluids of different temperatures flow through the flow channels. The channels can be provided by pressing a desired pattern to a metallic heat exchange plate or for example by corrugating the metallic plates to provide flow channels. In a variant called plate and fin heat exchanger, the heat exchange package comprises vertically packed flat plates with a fin plate connected to the flat plate, and the flat plates and the fin plates are packed alternatingly in the plate package. The purpose of the corrugated pattern and the fins is to provide a number of flow channels providing an increased heat exchange area.
The heat exchanger plates may be arranged as a package between end plates and all the plates may be joined together by brazing. In some variants pressure plates, which press the heat exchanger plates and the end plates towards each other, may be used. To be able to transfer heat between the fluids, flow channels for the respective fluids are needed, and this can be achieved in different manners depending on the heat exchanger type and the fluids in questions, as mentioned above.
There are different types of plate heat exchangers (PHE) and the plate heat exchangers may be adapted for different types of thermal fluids. Well-known PHEs include for example brazed heat exchangers, in which flows of the thermal fluids are normally arranged in a counter current manner in separate channels. No gaskets or similar need to be used to separate the fluids. In the heat exchangers fluids of initially different temperatures flow and transfer heat from one fluid to the other.
Plate and fin type of heat exchangers are well known in the art. Example of a brazed plate and fin heat exchanger is disclosed by US4673551 .
Despite existing brazed PHE:s and/or plate and fin heat exchangers solutions, there is still a need for improvements especially in the assembly of such plate heat exchangers. Especially, there is a need to simplify the assembly and ensure good edge sealing of the plates in the package. Further, there is a need to improve the thermal performance of plate heat exchangers.

Summary

When manufacturing plate heat exchangers, such as fin and plate heat exchangers, fin plates and so-called flat plates are assembled alternatingly on top of each other to form a plate package with flow channels. After a desired package height is reached, the plates are permanently joined together by for example brazing, which requires treatment with heat. When increasing the size of the plate heat exchangers, permanently joining the plates may become more difficult. Especially when brazing is done on plate packages with a flank portion of the plates as an edge sealing, the joining becomes more difficult the larger the plate sizes are. Especially in view that brazing requires treatment with heat, a larger plate may move and grow more than a smaller plate during brazing but the required tolerances on the flanks are constant. Supplying sufficiently filler material on the flank during brazing is therefore critical.
It is thus an objective of the present invention to mitigate, alleviate or eliminate one or more of the above-identified disadvantages in the prior art. It is an objective to provide solutions for heat exchangers which provide for improved thermal performance. It is also an objective to provide a robust heat exchanger.
It is a further objective to provide a simple method for assembly of a plate package.
The above-mentioned objectives are attained by the present invention as defined in the appended claims. Especially, the present invention describes a solution on how additional filler material can be supplied to the flank area during brazing to ensure that sufficient amount of the filler material is present to seal the unit. A flank solution with brim is a well-known design to increase the flank stiffness which for large units is especially important.
The present invention thus relates to a plate heat exchanger comprising a heat exchange plate package comprising:

a plurality of vertically packed first heat exchange plates and optionally a plurality of second heat exchange plates alternatingly arranged between the first heat exchange plates, wherein
each first heat exchange plate comprises a peripheral flank portion which transitions via a transition area to a peripheral brim portion, which extends outwardly from the flank portion, the flank and brim portions being arranged on two opposing longitudinal sides of each first heat exchange plate, wherein
the flank portions of adjacent first heat exchange plates are permanently joined together such that a longitudinally extending flow channel is formed between the adjacent first heat exchange plates, and wherein each first heat exchange plate comprises a heat exchange portion, which has a transversal extension between the peripheral flank portions; and wherein
the transition areas and/or brim portions comprise a braze filler recess and/or an angled braze filler receiving surface portion adapted for receiving the braze filler and spreading it to the flank portions.

Due to the braze filler recess and/or angled braze filler receiving portions in the transition areas and/or in the brim portions, it is possible to provide a sufficient amount of braze filler and distribute it evenly between two adjacent flanks to ensure proper permanent joining of the first heat exchange plates. Thereby improved thermal performance of the plate heat exchanger can be obtained.
The flank portions may have a flank angle of inclination in respect to a normal of the heat exchange portion, the flank angle being less than 45°, such as from 0° to 30°. In this way, the first heat exchange plates may be joined together in an improved manner.
The brim portions may have a brim angle of inclination in respect to the normal N of the heat exchange portion, which is larger than the flank angle. The brim angle may be less than or equal to about 90°. By the brim, a robust heat exchanger package is obtained.
The transition areas may comprise the angled braze filler receiving surface portion, which has an angle which is smaller than the brim angle and larger than a flank angle in respect to the normal of the heat exchange portion. In this way a simplified structure for the heat exchanger package is obtained.
According to a further variant, the brim portions may comprise the angled braze filler receiving surface portion which has an angle which is larger than the flank angle in respect to a normal of the heat exchange portion. Thereby, a further simplified structure for the heat exchanger package is obtained.
The braze filler recess in the brim portions may comprise one or more grooves or openings towards the flank portions distributed along the longitudinal extension of the first heat exchange plates, through which grooves or openings the braze filler is adapted to be supplied to an area between the flank portions. The grooves contribute to spreading of the braze filler on desired positions in an effective way.
Each brim portion may have a peripheral end, and wherein the braze filler recess is comprised between the transition area and the peripheral end of the brim portion. In this way the braze filler material may be applied to the recess in a simplified way.
The plate package may comprise the second heat exchange plates being fin plates. The fin plate may be is placed to the heat exchange portion of each first heat exchange plate. The fin plates may comprise a plurality of longitudinally extending fins which form in a transversal direction parallel guide channels for a heat exchange medium. Thus, in this way a plate and fin heat exchanger is provided.
According to a further aspect of the invention a method for assembling the plate heat exchanger is provided, the method comprising the steps of:

i. providing first heat exchange plates comprising the peripheral flank portions and brim portions, and braze filler recess and/or an angled braze filler receiving surface in the transition areas and/or brim portions for receiving and spreading a braze filler to the flank portions;
ii. optionally providing the second heat exchange plate on the heat exchange portion of the first heat exchange plate;
iii. placing a next first heat exchange plate and the optional second heat exchange plate on the preceding first heat exchange plate such that at least a portion of the flank portions of the latter first heat exchange plate is in contact with the flank portions of the preceding first heat exchange plate and such that the optional second heat exchange plate is in contact both with the first heat exchange plate and with the latter first heat exchange plate;
iv. providing the braze filler to the braze filler recesses and/or angled surface portions;
v. repeating the steps i)-iv) until the number of the plates in the package reaches a target number.
vi. permanently joining the flat plates and the optional fin plates together by means of heat to form the plate package.

The step iv) may comprise connecting the flank portions of the first heat exchange plates to the flank portions of the next first heat exchange plate such that they overlap in height direction of the package. The permanently joining in the step vii) may be performed by means of brazing or joining by means of the material of the first exchange plates by application of a melting depressant composition applied to the first exchange plates prior to being heated.
By the method a plate package with improved thermal performance is provided.

Brief descriptions of the drawings

The above objectives, as well as additional objectives, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present invention, when taken in conjunction with the accompanying drawings.

Fig. 1 is a schematical drawing showing a plate heat-exchanger in a perspective view.
Fig. 2 shows a schematic cross-sectional illustration along the line X-X shown in Fig. 1 of a plate and fin heat exchanger comprising a flank portion and a brim portion.
Fig. 3 shows a schematic cross-sectional illustration along the line X-X shown in Fig. 1 of a plate heat exchanger comprising a flank portion and a brim portion.
Fig. 4a and 4b illustrate a perspective view and a view from the side, respectively of a variant of a braze filler recess in the brim portion of the flat plate.
Fig. 5 illustrates a side view of a variant of a braze filler recess in the transition area between the flank portion and the brim portion.
Fig. 6 illustrates a side view of a further variant of a braze filler recess in the transition area between the flank portion and the brim portion.
Fig. 7 illustrates a side view of a variant of an angled area for the braze filler in the transition area between the flank portion and the brim portion.
Fig. 8 illustrates a side view of a variant of an angled brim portion for receiving the braze filler.

Detailed description

Today's process technologies often involve heat exchangers for improving the energy efficiency of processes. It has been found that improved assembly and thermal performance of the PHE as mentioned above are achieved by the heat exchanger comprising the plate package of the present invention and by assembling the plate heat exchanger according to the method of the present invention. The solution of the present invention will now be described with reference to the accompanying drawings showing examples of the invention. The invention may, however, be embodied in other forms and should not be construed as limited to the herein disclosed example embodiments. The disclosed embodiments are provided to fully convey the scope of the invention to the skilled person.
According to a first aspect of the present invention, a plate heat exchanger, which may be a plate and fin heat exchanger is provided. According to a further aspect a method of assembling a plate package of the plate heat exchanger is provided.
Reference is made to Fig. 1, which shows a plate heat exchanger 1 with a plate package 2 comprising a plurality of heat exchanger plates, which extend in a longitudinal and transversal direction. By the longitudinal direction L of the heat exchanger is meant a direction extending between a respective inlet port 16a or 20a or outlet port 20b and 16b, and as illustrated in Fig. 1. A first fluid 18 and a second fluid 22 are fed through the respective inlets 16a and 20a and they leave the heat exchanger 1 through the outlet ports 16b, 20b, respectively. A transversal direction T of the plate heat exchanger 1 is a direction perpendicular to the longitudinal direction L in the same plane. A height direction H is a direction extending perpendicularly to the plane of the longitudinal-transversal directions.
The first heat exchange plates may be pressed plates with a pressed channel design that form guide channels for a heat exchange medium. Alternatively, the first heat exchange plates may be so-called "flat plates" that are configured to be used together with fin plates that form guide channels for a heat exchange medium. These flat plates may be essentially flat at least in the heat exchange portions but may include some pressed sections. For example, the area around inlet and outlet ports may comprise pressed sections. Additionally, the distribution area distributing flow between the inlets and outlets and fin plate section may comprise pressed sections. The first heat exchange plates with pressed channel design that form guide channels for a heat exchange medium are configured to be used without fin plates and comprise the pressed fluid guide channels also in the heat exchange portion. By a fin plate is meant a plate comprising a fin design, which may be corrugated to the plate. In a plate and fin heat exchanger, flat plates are used in combination with fin plates.
The first and second heat exchanger plates are usually metallic plates, which comprise or consist of a metal or a metal alloy. Generally, the material for the second heat exchanger plates, such as fin plates, and for the first heat exchanger plates, such as the above described flat plates or plates with pressed channel design, may be any suitable and commonly used, such as stainless steel, aluminium, copper, nickel, tantalum, titanium, or alloys thereof, but are not limited thereto. The materials may be the same or different for the fin plates and the flat plates. Generally, both the fin plates and the flat plates may have a thickness of from 0.08 to 5.0 mm, or from 0.3 to 3.0 mm. The thickness of the fin plates may be the same or may be different in the package. The thickness of the flat or pressed plates may be from 0.25 to 5 mm and in the package the thickness may be the same for all flat or pressed plates, except for the end plates, which may be thicker. The fin plates may be made of a thinner material and the material may have a thickness from 0.08 to 5 mm, or from 0.1 to 1 mm. The flat, pressed or fin plates may have the same thickness, or they may initially have the same thickness in the whole package. However, the manufacturing process may affect the thickness of the fin plates, whereby the final thickness of the fin plates may be smaller than the thickness of the flat plate. It is thus possible that the metal plate thickness for the fin plates is thicker or thinner than the metal plate thickness for the flat plates but is preferably thinner than the thickness of the flat plates.
Reference is now made to Fig. 2, in which a cross-sectional view of a plate and fin heat exchanger plate package 2 is schematically shown along the line X-X shown in Fig. 1. The plate package 2 comprises a plurality of vertically packed first heat exchange plates 4, 4' ("flat plates") and a plurality of second heat exchange plates 3, ("fin plates"). In the illustrated example, the first heat exchange plates 4, 4' are flat plates and the second heat exchange plates 3 are fin plates. The flat plates 4 and the fin plates 3 are alternatingly arranged in the package so that the fin plates 3 are placed in between the first heat exchange plates 4, 4'.
In Fig. 3 another variant of the heat exchange plates and the plate package 2 is shown. The first heat exchange plates 4, 4' in this variant are pressed plates having a fluid channel design pressed to the surface of the plates.
Fig. 2 and 3 both illustrate an assembled plate package 2 after permanent joining of the plates. In each of the variants shown in Fig. 2 and 3, the first heat exchange plates 4, 4' comprises a peripheral flank portion 4a (shown in Fig. 3) and 4b on the two opposing longitudinal L sides of the respective first heat exchange plate 4, 4'.The peripheral flank portions 4a, 4b; 4a', 4b' transition via a respective rounded corner portion, herein referred to a transition area 7a, 7b; 7a', 7b' to a peripheral brim portion 5a, 5b; 5a', 5b'. In the illustrated examples in Fig. 2 and 3, the flank portions are inclined outwards seen from a heat exchange portion 14, and the brim portions extend outwardly from the flank portions. The flank and brim portions are arranged on the two opposing longitudinal sides of each first heat exchange plate 4, 4'. Each first heat exchange plate 4, 4' comprises the heat exchange portion 14, which has a transversal extension between the peripheral flank portions 4a, 4b.
In Fig. 2, the fins 32 of the fin plates 3 are arranged connected to the heat exchange portion 14 of the flat plates 4, 4'. The fin plates 3 comprise a plurality of longitudinally extending fins 32 arranged in the heat exchange portion 14 of the flow channels 12 between the adjacent flat plates 4, 4'. The fins 32 form in a transversal direction parallel guide channels for a first and second heat exchange medium 18, 22 respectively.
In Fig. 2 and 3 it is shown that the heat exchange portion 14 of the first heat exchange plate 4; 4' transitions to the flank portions 4a, 4b via rounded corner portions 44a, 44b on the respective longitudinal side of the first heat exchange plate 4, 4'. Further it is shown that the flank portions 4a and 4b of the first exchange plates 4, 4' transition to a respective brim portion 5a, 5b and 5a', 5b' via a transition area 7a, 7b and 7a', 7b'. In the package 2, each flank portion 4a, 4b is permanently joined to an adjacent flank portion 4a', 4b' of an adjacent first heat exchange plate 4' such that a longitudinally extending flow channel 12 is formed between the adjacent first heat exchange plates 4, 4'. In this flow channel the cold and warm fluids are arranged to flow in separated channels formed by fins 32 of the fin plates.
The longitudinally extending fins 32 may have different cross-sectional shapes, which may also vary along the longitudinal and/or transversal extension. Generally, the fins may have a wave shape and be parallel in a transversal direction, each wave having wave peaks (p) and wave troughs (t). The fins may be substantially straight along the longitudinal extension L. However, the fins may have another shape along the longitudinal extension. For example, the shape may be wavy along the longitudinal extension. The fins may in the cross-section have a wave-shape, e.g. substantially a sinus-wave shape. Alternatively, the fins may have a rectangular or triangular cross-section. A further variant could be so called offset strip-shape in which a wavy shape is resembled with rectangular blocks shifted in a wavy manner in the transversal direction. Further, the fins may have different surface treatment along the fin, and they may be for example perforated or louvered.
Fig. 3 shows that the flank portions 4a, 4b; 4a', 4b' have a flank angle (FA) of inclination in respect to a normal N of the heat exchange portion 14. The flanks may be inclined outwards from the normal N of the heat exchange portion 14. The flank angle FA may be less than 45°, such as from 0° to 30°. When the flank angle is 0°, the flank is perpendicular to the heat exchange portion 14, and thus inclined at an angle of 90° in respect to the heat exchange portion 14. The brim portions 5a, 5b and 5b, 5b' have a brim angle BA of inclination which is larger than the flank angle FA in respect of the normal N of the heat exchange portion 14. This means that the brim portions extend outwardly from the flank portions. The brim angle BA may be less than or equal to about 90°. Thus, the brim portions may be parallel to the heat exchange portion 14 of the first heat exchange plate. The angles of inclination of the flank and brim portions apply also to the fin and plate heat exchanger shown in Fig. 2. When the package is manufactured, the flank portions of the first heat exchange plates 4, 4' are permanently joined together such that the longitudinally extending flow channel 12 is formed between the adjacent first heat exchange plates 4, 4', and wherein each first heat exchange plate 4, 4' comprises the heat exchange portion 14, which has a transversal extension between the peripheral flank portions 4a, 4b; 4a', 4b'.
Reference is now made to Fig. 4a, 4b, 5 and 6, in each of which a plate package 2 as explained in connection with Fig. 2 and 3 is shown. The parts of the plate package correspond to the parts shown in Fig. 2 and 3, and the reference signs of those drawings apply mutatis mutandis. According to the present invention and as shown by Fig. 4a and 4b in different views, the brim portions 5a, 5a' (5b, 5b' not shown) may in a symmetrical manner comprise a braze filler recess 52, which is adapted for receiving a braze filler 50. As Fig. 4b shows, each of the brim portions 5a (5b not shown) has a peripheral end 51, shown only in connection with one heat exchanger plate 4. The braze filler recess 52, which is shown only in connection with one heat exchanger plate 4, may according to a variant be comprised between the transition area 7a, 7a' (and correspondingly 7b, 7b' which are not shown in the figures) and the peripheral end 51, 51' of the respective brim portion. The braze filler recess in the brim portion 5a, 5a' may comprise one or more grooves or openings 54 towards the flank portions 4a, 4a'. The braze filler is adapted to be supplied through the grooves 54 or openings and spread to an area between adjacent flank portions 4a, 4a' and 4b, 4b' when the plate package is heated for permanent joining of the heat exchanger plates. The grooves 54 may be placed or distributed along the longitudinal extension of the first heat exchange plates, for example intermittently along the longitudinal extension of the first heat exchange plates to ensure uniform spreading of the braze filler to the flank portions 4a, 4a' and 4b, 4b'. According to the invention thus, the pressed groove or recess 52 in the brim portions provide supply channels for the braze filler, see Figure 4a and 4b. With this solution additional filler material can be applied (see Figure 4b) and during brazing the filler will flow and move by capillary forces to the flank portions where needed.
In Fig. 5 and 6 further embodiments of the present invention are shown. In both figures, the transition area 7a (and correspondingly 7a', and 7b, 7b', which are not shown in the drawings) from the flank portion 4a to the brim portion 5a comprises a braze filler recess 71 (Fig. 5) and a braze filler recess 73 (Fig. 6). The brace filler recess 71 in Fig. 5 has in a cross-sectional view an arch shape which is adapted to receive the braze filler. At the same time the arc shape is inclined towards the flank portion so that the braze filler can be more easily spread to the flank portions. In Fig. 6, the recess has a "step-like" or a "square-like" corner shape in a cross-sectional view. The corner may have an angle of 90° or more to ensure that the braze filler can be more easily spread to the flank portions 4a, 4b.
In Fig. 7 and 8 further embodiments of the present invention are shown. In Fig. 7, the transition area between the flank portion 4a (and correspondingly 4a', and 4b, 4b', which are not shown in the drawings) and the brim portion 5a (and correspondingly 5a', and 5b, 5b', which are not shown in the drawings), comprises or consists of an angled braze filler receiving surface portion 75 adapted for receiving the braze filler and spreading it to the flank portions 4a. By the angled receiving surface portion 75 is meant a surface that is inclined at an angle RA in respect of the normal N of the heat exchange area 14 of the first heat exchanger plate 4. The angle RA is smaller than the brim angle BA and larger than a flank angle FA, all in respect to a normal N of the heat exchange portion and as in the illustrated example. Depending on the brim angle and flank angle, the angle RA may be from 20-80°, for example from 30-70°. In this way the braze filler can be efficiently spread between the flanks while a simple geometry for the plate package is provided.
In Fig. 8 a further variant of the invention is shown. In this variant, the brim portion 5a in itself provides an angled braze filler receiving surface portion 55. The transition area 7a is then the angled portion between the flank portion 4a and the brim portion 5a. The brim angle BA in this variant can be from 20-60° in respect to a normal N of the heat exchange portion, for example from 30-50° in respect to a normal N of the heat exchange portion. As above, the brim angle is larger than the flank angle to ensure tat the braze filler can be efficiently spread between the flanks.
The braze filler recesses and/ or the angled portions as exemplified above ensure an improved spreading of the braze filler to the flank portions, and thereby a better permanent joining of the plates to each other can be obtained.
The present invention further relates to a method for assembling the plate heat exchanger. In the first step i) a first heat exchange plate 4 comprising the peripheral flank portions 4a, 4b and brim portions 5a, 5b on the longitudinal sides, i.e. lateral sides, of the first plate is provided. The flank portions 4a, 4b, delimit the heat exchange portion 14 of the flat plate as described above. The first heat exchange plates comprise a braze filler recess and/or an angle braze filler receiving surface 75 in the transition areas (7a, 7b; 7a', 7b') and/or brim portions (5a, 5b; 5a', 5b') to receive and spread a braze filler to the flank portions. Step ii) is optional and relates to optionally providing the second heat exchange plate (3) on the heat exchange portion (14) of the first heat exchange plate (4). The second plate 3, may be a fin plate 3 with longitudinally extending fins 32.
In the step iii) a next first heat exchange plate 4' and the optional second heat exchange plate 3 are placed on the preceding first heat exchange plate 4 such that at least a portion of the flank portions 4a', 4b' of the latter first heat exchange plate 4' is in contact with the flank portions 4a, 4b of the preceding first heat exchange plate 4, see Fig. 2 and 3. Fig. 3 shows that the optional second heat exchange plate 3 is in contact both with the first heat exchange plate 4 and with the latter first heat exchange plate 4'.
To provide a plate package 2, a desired number of first heat exchange plates 4, 4' and fin plates 3 are packed on top of each other. A next flat plate 4' is placed on top of the preceding fin plate 3 such that at least a portion of the next flat plate 4' is in contact with the fins 32 of the fin plate 3 fitted in the heat exchange portion 14 of the preceding flat plate 4. The first heat exchange plates 4, 4' thus form the guide channels together with the fins 32 for the respective first and second heat exchange mediums 18, 22. The flank portions 4b, 4b', and in a similar manner 4a and 4a', of the first heat exchange plates 4, 4' overlap in height direction h of the package 2. As can be seen in Fig. 2 and 3, the heat exchange portion 14 of the flat plate 4 transitions to the flank portion 4b, and similarly to 4a, via rounded corner portions 44a, 44b on the respective side of the first heat exchange plate 4.
In the next step iv), the braze filler is provided to the braze filler recess and/or angled surface portions.
In the step vi) the method comprises repeating the steps i-iv until the number of the plates in the package reaches a target number.
The method further comprises a step vi) comprising permanently joining the flank portions 4a, 4a' and 4b, 4b' on the respective longitudinal sides of the adjacent flat plates 4, 4' to provide a plate package 2.
The permanent joining may be performed by for example brazing or by joining by means of the material of the heat transfer plates by application of a melting depressant composition applied to the heat transfer plates prior to being heated, e.g., as discussed in WO 2013144211 . Thus, the permanent joints may be formed by a joining method in which the plates are subjected to a heat lower than the melting point of the heat transfer plates. Such joining methods may be one of brazing with an added brazing material in the form of a foil, a paste, or a powder comprising e.g., copper or nickel, or joining by means of the material of the heat transfer plates by application of a melting depressant composition applied to the heat transfer plates prior to being heated. Thus, by braze filler in the present application is means both brazing material and the melting depressant composition. By manufacturing the plate package as described above, improve the thermal performance of the heat-exchanger.
The flank portions 4a, 4b and the brim portions 5a, 5b on the respective longitudinal sides of the flat plate 4 can be provided upstream or in conjunction with the step i) in the method. The pressing may be performed by means of a pressing tool, which can be any suitable metal working tool known in the art. The permanently joining in the step vi) may be performed by means of brazing or joining by means of the material of the heat transfer plates by application of a melting depressant composition applied to the heat transfer plates prior to being heated.

Claims

A plate heat exchanger (1) comprising a heat exchange plate package (2) comprising:
a plurality of vertically packed first heat exchange plates (4, 4') and optionally a plurality of second heat exchange plates (3) alternatingly arranged between the first heat exchange plates, wherein

each first heat exchange plate comprises a peripheral flank portion (4a, 4b; 4a', 4b') which transitions via a transition area (7a, 7b; 7a', 7b') to a peripheral brim portion (5a, 5b; 5a', 5b'), which extends outwardly from the flank portion, the flank and brim portions being arranged on two opposing longitudinal sides of each first heat exchange plate, wherein

the flank portions of adjacent first heat exchange plates are permanently joined together such that a longitudinally extending flow channel (12) is formed between the adjacent first heat exchange plates, and wherein each first heat exchange plate comprises a heat exchange portion (14), which has a transversal extension between the peripheral flank portions; and wherein

the transition areas and/or brim portions comprise a braze filler recess (71, 73; 52) and/or an angled braze filler receiving surface portion (75; 55) adapted for receiving the braze filler and spreading it to the flank portions.
The plate heat exchanger according to claim 1, wherein the flank portions have a flank angle (FA) of inclination in respect to a normal (N) of the heat exchange portion (14), the flank angle (FA) being less than 45°, such as from 0° to 30°.
The plate heat exchanger according to claim 2, wherein the brim portions (5a, 5b; 5a', 5b') have a brim angle (BA) of inclination in respect to the normal (N) of the heat exchange portion (14), which is larger than the flank angle (FA).
The plate heat exchanger according to claim 3, wherein the brim angle (BA) is less than or equal to about 90°.
The plate heat exchanger according to claim 2-4, wherein the transition areas (7a, 7b; 7a', 7b') comprise the angled braze filler receiving surface portion (75) which has an angle (RA) which is smaller than the brim angle (BA) and larger than a flank angle (FA) in respect to the normal (N) of the heat exchange portion (14).
The plate heat exchanger according to any of claims 2-5, wherein the brim portions (5a, 5b; 5a', 5b') comprise the angled braze filler receiving surface portion (55) which has an angle (BA) which is larger than the flank angle (FA) in respect to a normal (N) of the heat exchange portion (14).
The plate heat exchanger of any one of the preceding claims, wherein the braze filler recess (52) in the brim portions comprises one or more grooves or openings (54) towards the flank portions, the grooves or openings being distributed along the longitudinal extension of the first heat exchange plates, through which grooves or openings the braze filler is adapted to be supplied to an area between the flank portions.
The plate heat exchanger of any one of the preceding claims, wherein each brim portion (5a, 5b; 5a', 5b') has a peripheral end (51a, 51b; 51a', 51b'), and wherein the braze filler recess is comprised between the transition area (7a, 7b; 7a', 7b') and the peripheral end of the brim portion.
The plate heat exchanger according to any one of the preceding claims, wherein the plate package comprises the second heat exchange plates (3) being fin plates.
The plate heat exchanger according to claim 9, wherein the fin plate (3) is placed to the heat exchange portion (14) of each first heat exchange plate (4, 4').
The plate heat exchanger according to claim 10, wherein the fin plates (3) comprise a plurality of longitudinally extending fins (32) which form in a transversal direction parallel guide channels for a heat exchange medium (18, 22).
A method for assembling the plate heat exchanger (1) of any one of claims 1 to 9 comprising the steps of:
i. providing first heat exchange plates (4, 4') comprising the peripheral flank portions (4a, 4b; 4a', 4b') and brim portions (5a, 5b; 5a', 5b'), and braze filler recess and/or an angled braze filler receiving surface (75; 55) in the transition areas (7a, 7b; 7a', 7b') and/or brim portions (5a, 5b; 5a', 5b') for receiving and spreading a braze filler to the flank portions;

ii. optionally providing the second heat exchange plate (3) on the heat exchange portion (14) of the first heat exchange plate (4, 4');

iii. placing a next first heat exchange plate (4') and the optional second heat exchange plate (3) on the preceding first heat exchange plate (4) such that at least a portion of the flank portions (4a', 4b') of the latter first heat exchange plate (4') is in contact with the flank portions (4a, 4b) of the preceding first heat exchange plate (4) and such that the optional second heat exchange plate (3) is in contact both with the first heat exchange plate (4) and with the latter first heat exchange plate (4');

iv. providing the braze filler to the braze filler recesses and/or angled surface portions;

v. repeating the steps i)-iv) until the number of the plates in the package reaches a target number.

vi. permanently joining the flat plates and the optional fin plates together by means of heat to form the plate package (2).
The method of claim 12, wherein in the step iv) comprises connecting the flank portions (4a, 4b) of the first heat exchange plates (4) to the flank portions (4a', 4b') of the next first heat exchange plate (4') such that they overlap in height direction of the package.
The method of any of claims 12 or 13, wherein the permanently joining in the step vii) is performed by means of brazing or joining by means of the material of the first exchange plates by application of a melting depressant composition applied to the first exchange plates prior to being heated.