Method for assembling a plate package for a plate-and-fin heat exchanger and plate-and-fin heat exchanger

Abstract

The present disclosure relates to a method for assembling a plate package for a plate-and-fin heat exchanger (1) comprising a plurality of flat plates (4, 4') and a plurality of fin plates (3), each of the flat plates (4, 4') having peripheral flank portions (4a, 4b, 4a', 4b') on two opposite longitudinal sides of the respective flat plate, each flank portion being permanently joined to an adjacent flat plate (4') such that longitudinally extending flow passages (12) are formed between the adjacent flat plates (4, 4'), each flat plate (4, 4') having a heat exchange portion (14) having a lateral extension between the peripheral flank portions (4a, 4b, 4a', 4b'). The fin plate (3) comprises a plurality of longitudinally extending fins (32) disposed within the heat exchange section (14), the fins (32) forming transversely parallel guide channels (34) for the first heat exchange medium (18) and the second heat exchange medium (22), respectively. The fin plate (3) and the flat plate (4, 4') are permanently attached to each other. The method includes providing a fin plate that is transversely larger than the heat exchange section and placing it on the flat plate of the package before permanently joining the plates to each other. In this manner, the size of the bypass gap can be minimized.

Description

[Technical Field]

[0001] The present invention relates to a method for assembling a plate package of a plate-and-fin heat exchanger and to a plate-and-fin heat exchanger as defined in the introductions of the independent claims attached hereto. [Background technology]

[0002] A plate heat exchanger (PHE) typically comprises multiple metal heat exchange plates arranged in an aligned fashion to form flow channels between them. The heat exchange plates are used to separate two fluids and transfer heat between them. In a plate heat exchanger, fluids of different temperatures flow through channels, which can include fin plates that provide several channels for increased heat exchange area. The fins may be provided by corrugating thin metal sheet plates. The heat exchanger plates may be arranged as a package between end plates, or all plates may be joined by brazing. In some variations, pressure plates may be used to press the heat exchanger plates and end plates toward each other. To allow heat transfer between the fluids, a channel for each fluid is required, which can be achieved in different ways depending on the type of heat exchanger and the fluid in question.

[0003] There are various types of plate heat exchangers (PHEs), which may be adapted to various types of thermal fluids. Known PHEs include, for example, brazed heat exchangers, in which the thermal fluid flows are typically arranged in separate channels in a countercurrent manner. No gaskets or similar are required to separate the fluids. In the heat exchanger, fluids initially at different temperatures flow, transferring heat from one fluid to the other.

[0004] Plate and fin type heat exchangers are well known in the art. An example of a brazed plate and fin heat exchanger is disclosed in U.S. Pat. No. 4,673,551.

[0005] Despite existing brazed plate-and-fin heat exchanger solutions, there is still a need for improvements in the assembly of such plate heat exchangers. In particular, there is a need to simplify assembly. Additionally, there is a need to improve the thermal performance of plate heat exchangers. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 4,673,551 Summary of the Invention [Problem to be solved by the invention]

[0007] In a finned plate heat exchanger, finned plates and flat plates are alternately assembled on top of each other to form a plate package with flow channels. After reaching the desired package height, the plates are permanently joined together, for example, by brazing, which requires heat treatment. In the context of this disclosure, it should be noted that after brazing, bypass voids are formed at each longitudinal side edge of the finned plates. The voids deteriorate the thermal performance of the heat exchanger and are therefore undesirable. Therefore, an object of the present invention is to minimize the size of the voids.

[0008] It is therefore an object of the present invention to mitigate, alleviate or eliminate one or more of the above-identified disadvantages of the prior art. It is an object to provide a heat exchanger solution that provides improved thermal performance. It is also an object to provide a robust heat exchanger.

[0009] It is a further object to provide a simple method for assembling a plate package.

[0010] The above objects are achieved by the present invention as defined in the appended claims. [Means for solving the problem]

[0011] According to a first aspect, there is provided a method for assembling a plate package for a plate-and-fin heat exchanger, the plate package comprising a plurality of flat plates and a plurality of fin plates. Each flat plate has peripheral flank portions on two opposing longitudinal sides of the respective flat plate. Each flank portion is permanently joined to an adjacent flat plate such that longitudinally extending flow passages are formed between the adjacent flat plates, and each flat plate has a heat exchange portion having a lateral extension between the peripheral flank portions. The fin plate comprises a plurality of longitudinally extending fins disposed within the heat exchange portion, the fins forming lateral parallel guide channels for a first heat exchange medium and a second heat exchange medium, respectively. The method comprises the following steps:

[0012] i. providing a flat plate with peripheral flank portions on opposite longitudinal sides of the plate, the flank portions defining a heat exchange portion of the plate; ii. Providing a fin plate having longitudinally extending fins, the fin plate having a lateral extension greater than the lateral extension of the heat exchange portion of the plate; iii. Pressing the opposing sides of the fin plate laterally towards each other so that the fin plate fits between the flank portions and over the heat exchange portion of the flat plate; iv. placing a next flat plate in the package on top of the preceding fin plate in the package so that at least a portion of the next flat plate contacts the fins of the fin plate fitted to the heat exchange portion of the preceding flat plate and the flank portion of the flat plate is connected to the flank portion of the next flat plate; v. repeating steps i) to iv) until the number of plates in the package reaches the target number; vi. permanently joining the flat plate with the flank portions to the fin plate.

[0013] This method provides a plate package with improved thermal performance, since the lateral extension of the fin plate is greater than necessary compared to the surface on which it is to be placed, thus minimizing the size of the bypass voids that are formed after permanent bonding of the plate in the package.

[0014] In step iv), the flanks of a flat plate may be connected to the flanks of the next plate so that they overlap in the height direction of the package, thus providing a compact structure.

[0015] The heat exchange portion of the plate can transition to the flank portion via rounded corners on each side of the plate. In step iii), pressing the flank portion can include minimizing the radius of the rounded corners. In this way, the fins can be brought closer to the flanks before permanent bonding. This can reduce the size of the bypass gap as the fins are closer to the flanks when the package is heated during permanent bonding, thereby improving thermal performance.

[0016] Thus, step iii) may further comprise minimising the radius so that it is smaller than the height of the channel, preferably less than 0.5h, and / or so that it is smaller than twice the thickness of the plate, preferably less than 1.1 times the thickness of the plate, and / or so that the distance between the inner surface of the flank portion and the outermost part of the fin closest to the flank portion, at the midpoint of the height of the channel, is smaller than the height of the channel, preferably less than 0.5h.

[0017] In step iii), the pressing step can include adjusting a first distance measured at the midpoint of the height of the channel between the inner surface of the flank portion and an outermost part of the fin closest to the flank portion such that the first distance is smaller than a second distance between two adjacent fins or such that the first distance is smaller than the height of the channel, thereby minimizing the size of bypass voids formed during permanent bonding.

[0018] The first distance may be less than 0.7h, preferably less than 0.5h, at the midpoint of the height of the flow channel. The smaller the distance, the smaller the bypass gap.

[0019] The pressing step may alternatively or additionally include adjusting a first hydraulic diameter between an inner surface of the flank portion and an outermost part of the fin closest to the flank portion such that the first hydraulic diameter is less than or equal to a second hydraulic diameter between two adjacent fins measured at a point along the longitudinal extension of the fins where the hydraulic diameter is smallest.

[0020] Step ii) may include providing a fin plate in which the fin wall length of the outermost fin is less than the height of the flow passage, with the fins opening toward the heat exchange portion of the plate. In this way, the outermost fin can be positioned close to the inner surface of the flank, thus further minimizing bypass gaps. The fin wall length may be less than the height h of the flow passage, preferably less than 0.5h. Alternatively, the fin wall length is less than 0.25h.

[0021] The permanent bonding in step vi) may be performed by applying a melt suppressing composition applied to the heat exchanger plate before it is heated, by brazing, or by bonding utilizing the material of the heat exchanger plate.

[0022] According to a further aspect, a plate-and-fin heat exchanger is provided, comprising a plate package including a plurality of flat plates and a plurality of fin plates, each of which has peripheral flanks on two opposing longitudinal or lateral sides of the respective plate. Each flank is permanently bonded to an adjacent plate, suitably to its flank. The flanks are bonded such that longitudinally extending flow channels are formed between the adjacent plates. Each plate has a heat exchange portion having a lateral extension between the peripheral flanks. The fin plate includes a plurality of longitudinally extending fins disposed within the heat exchange portion of the flow channels between and in contact with the adjacent plates. The fins form transversely parallel guide channels for the first and second heat exchange media, respectively. The heat exchange portions of the flat plates transition to the flanks via rounded corners on each side of the plate, which are pressed so that the radius of the rounded corners is minimized and is smaller than the height of the flow channels, preferably less than 0.5h. Alternatively or additionally, the radius is adjusted to be less than twice the thickness of the plate (4), preferably less than 1.1 times the thickness of the plate (4). Alternatively or additionally, a first distance between the inner surface of the flank and the outermost fin, measured at the midpoint of the height of the flow passage, is less than a second distance between two adjacent fins, or the first distance is less than the height of the flow passage, and the fin wall length of the outermost fin is less than the height of the flow passage, such that the fin opens toward the heat exchange portion of the plate. In this way, bypass voids formed during permanent bonding in the region between the inner surface of the flank and the outermost fin can be minimized. Therefore, the bypass voids are configured to be minimized by adjusting the distance between the inner surface of the flank and the outermost fin and / or the bending radius of the flank.

[0023] According to one variant, the first hydraulic diameter between the inner surface of the flank portion and the outermost part of the fin closest to the flank portion may be adjusted to be less than or equal to the second hydraulic diameter between two adjacent fins, measured at the point where the hydraulic diameter is smallest along the longitudinal extension of the fins.

[0024] The above objects, as well as additional objects, features and advantages of the present invention, will be more fully understood by reference to the following illustrative and non-limiting detailed description of exemplary embodiments of the invention in connection with the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic perspective view showing a plate heat exchanger. [Figure 2] 2 is a schematic cross-sectional view of a plate-and-fin heat exchanger assembled according to a prior art method, taken along line XX shown in FIG. 1. [Figure 3a] 10A-10C show different shaped fins. [Figure 3b] 10A-10C show different shaped fins. [Figure 3c] 10A-10C show different shaped fins. [Figure 4] FIG. 1 shows steps i) to iii) of the method according to the invention. [Figure 5] FIG. 1 shows a prior art plate-and-fin heat exchanger in which the fins are constrained by the radius of the plate bending curve, thereby providing a large bypass gap between the flanks of the plate and the outermost fins of the fin plate. [Figure 6] FIG. 1 shows a plate-and-fin heat exchanger obtained by this method in which the size of the bypass gap is minimized by minimizing the bending radius of the flanks of the plates. [Figure 7a] FIG. 10 shows an example of fin cutting to obtain a minimum size of the bypass gap. [Figure 7b] FIG. 10 shows an example of fin cutting to obtain a minimum size of the bypass gap. [Figure 7c] FIG. 10 shows an example of fin cutting to obtain a minimum size of the bypass gap. [Figure 7d] FIG. 10 shows an example of fin cutting to obtain a minimum size of the bypass gap. [Figure 8]2 is a schematic cross-sectional view along line XX shown in FIG. 1 of a plate package with minimized bypass voids obtained by the method according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0026] Today's process technology often includes heat exchangers to improve the energy efficiency of the process. It has been found that the above objectives can be achieved by a heat exchanger comprising a plate package assembled according to the method of the present invention. It should be noted that improved thermal performance can be obtained, and the inventive solution will now be described with reference to the accompanying drawings, which show examples of the present invention. However, the present invention may be embodied in other forms and should not be construed as limited to the exemplary embodiments disclosed herein. The disclosed embodiments are provided so that the scope of the present invention will be fully conveyed to those skilled in the art.

[0027] According to a first aspect of the present invention, there is provided a method for assembling a plate package for a plate-and-fin heat exchanger. The plate package is shown in Figures 1 and 2, both of which are referred to equally. Thus, the plate package 2 of the plate-and-fin heat exchanger 1 comprises a plurality of flat plates 4 and a plurality of fin plates 3.

[0028] Generally, in this application, a flat plate refers to a plate without any pressed channels or fin design. A fin plate refers to a plate with a pressed channel or fin design. A plate is typically a metal plate, including or consisting of a metal or metal alloy. Generally, the materials of the fin plate and flat plate may be any suitable and commonly used material, such as, but not limited to, stainless steel, aluminum, copper, nickel, tantalum, titanium, or alloys thereof. The materials of the fin plate and flat plate may be the same or different. Generally, both the fin plate and flat plate may have a thickness of 0.08 to 5.0 mm, or 0.3 to 3.0 mm. The thickness of the fin plate may be the same or different within a package. The thickness of the flat plate may be 0.25 to 5 mm, and within a package, the thickness may be the same for all flat plates except for the end plates, which may be thicker. The fin plates may be thinner, having a thickness of 0.08 to 5 mm, or 0.1 to 1 mm, and they may have the same thickness throughout the package at first. However, during the pressing operation, the thickness of the fin plates may be affected, and the final thickness of the fin plates may be less than the thickness of the flat plate. Therefore, the metal thickness of the fin plates can be thicker or thinner than the metal thickness of the flat plate, but is preferably thinner than the thickness of the flat plate.

[0029] The longitudinal direction L of the heat exchanger refers to the direction extending between the inlet port 16a and the outlet port 20a, or between the inlet port 16b and the outlet port 20b, as shown in Figure 1. The transverse direction T is a direction perpendicular to the longitudinal direction L within the same plane. The height direction H is a direction extending perpendicular to the longitudinal and transverse plane.

[0030] Each flat plate 4 includes peripheral flank portions 4a, 4b on two opposing longitudinal sides L of the plate, as shown in FIG. 2, which illustrates the assembled plate package 2 after the plates are permanently joined. In FIG. 2, the flank portions 4a of the flat plate 4 are shown transitioning to edge portions 5a. Conversely, the flank portions 4b on the opposing longitudinal sides can transition to edge portions 5b, which are not shown in the photograph of FIG. 2. The edge portions may be omitted. In the package 2, each flank portion 4a, 4b is permanently joined to the flank portion of an adjacent flat plate 4 such that a longitudinally extending flow path 12 is formed between adjacent flat plates 4. In this flow path or channel, the cold and hot fluids are configured to flow through separated channels 34 formed by the fins 32 of the fin plate. Each flat plate 4 includes a heat exchange portion 14 having a lateral extension between the peripheral flank portions 4a, 4b, with the fins of the fin plate being connected to and arranged within the heat exchange portion 14. The fin plate 3 thus comprises a plurality of longitudinally extending fins 32 disposed between adjacent flat plates 4 in the heat exchange portion 14 of the flow passage 12. The fins 32 form transversely parallel guide channels 34 for the first and second heat exchange media 18 and 22, respectively.

[0031] The longitudinally extending fins 32 may have different cross-sectional shapes, which may vary along the longitudinal and / or lateral extension. Examples of different fin shapes are shown in Figures 3a-3c. Generally, the fins have corrugations, which may be parallel to the lateral direction, with each wave having a wave peak (p) and a wave trough (t) (see Figure 5). The fins may be substantially straight along the longitudinal extension L. However, the fins may have a different shape along the longitudinal extension. For example, the shape may be wavy along the longitudinal extension, as shown in Figure 3c. The fins may also have a wavy cross-section, e.g., substantially sinusoidal. Alternatively, the fins may have a rectangular or triangular cross-section, as shown in Figures 3a and 3b, respectively. A further variation may be a so-called offset strip shape, in which the wavy shape resembles a rectangular block shifted laterally. Furthermore, the fins may have different surface treatments along the fins, which may be perforated or louvered, for example.

[0032] FIG. 2 shows bypasses 30 (only the numbered ones are depicted) in the flow passages 12 of the heat exchanger plate package 2 after permanent bonding. The bypasses 30 are gaps between the outermost portion 38 of the fin wall 36 and the flank 4a, and correspondingly, on the opposite lateral side of the plate, between the flank 4b and the corresponding outermost portion 38 of the fin wall 36 on this side of the fin plate 3. In FIG. 2, the bypass gaps 30 are large. No heat exchange occurs between fluids of different temperatures in the bypass gaps 30. Therefore, the bypasses reduce the thermal performance of the heat exchanger. The objective of the present invention is to minimize the size of the bypasses in the flow passages, thus improving the thermal performance of the heat exchanger.

[0033] A heat exchanger with improved thermal performance can be obtained by the method of the present invention, and reference is now made to FIG. 4, which illustrates steps i) to iii) of the method. In the first step i), a flat plate 4 is provided with peripheral flank portions 4a and 4b on opposite longitudinal sides, i.e., lateral sides, of the flat plate. The flank portions 4a, 4b define the heat exchange portion 14 of the flat plate, as described in connection with FIG. 2. In step ii), a fin plate 3 is provided having longitudinally extending fins 32. The fin plate 3 has a lateral extension greater than the lateral extension of the heat exchange portion 14 of the flat plate. In the next step iii), the opposite sides of the fin plate 3 are pressed laterally toward each other so that the fin plate 3 fits between the flank portions 4a and 4b and over the heat exchange portion 14 of the flat plate. When the fin plate 3 is placed on the flat plate 4 and the fin plate 3 is released from pressing its lateral sides towards each other, the fin plate 3 can expand so that its lateral sides lean towards the flank portions 4a and 4b, as shown in Figure 4 using reference symbol iii)'.

[0034] To provide a plate package 2, a desired number of flat plates 4 and fin plates 3 are stacked one on top of the other. Referring to FIG. 5, how the package 2 can be provided is shown. Thus, after step iii), the next step is step iv), in which a next flat plate 4′ is placed on top of the preceding fin plate 3 so that at least a portion of the next flat plate 4′ contacts the fins 32 of the fin plate 3 that are fitted to the heat exchange portion 14 of the preceding flat plate 4. Thus, the flat plates 4, 4′ form guide channels 34 together with the fins 32 for the respective first and second heat exchange media 18, 22. The flank portions 4b, 4b′, as well as 4a, 4a′ (not shown) of the flat plates 4, 4′ overlap in the height direction h of the package 2. As can be seen in FIG. 5, the heat exchange portion 14 of the flat plate 4 transitions to the flank portion 4b (and similarly to 4a) via rounded corner portions 44 on each side of the flat plate 4.

[0035] Step v) of the method involves repeating steps i-iv until the number of plates in the package reaches a target number.

[0036] The method further includes step vi) of permanently joining flank portions 4a, 4a' and 4b, 4b' on the respective longitudinal sides of adjacent flat plates 4, 4' to provide a plate package. The permanent joining step may be performed by, for example, brazing, or by bonding using the material of the heat transfer plate, for example, by applying a melt-suppressing composition to the heat transfer plate before it is heated, as described in WO2013144211. Thus, the permanent joint may be formed by a bonding method in which the plates are subjected to a temperature below the melting point of the heat transfer plate. Such a bonding method may be one of brazing with an added brazing material in the form of a foil, paste, or powder containing, for example, copper or nickel, or bonding using the material of the heat transfer plate by applying a melt-suppressing composition to the heat transfer plate before it is heated.

[0037] By manufacturing the plate package as described above, it is possible to minimize the bypass air gap, thereby improving the thermal performance of the heat exchanger.

[0038] The flank portions 4a, 4b on each longitudinal side of the plate 4 may be provided upstream of or in conjunction with step i) of the method. The pressing step may be performed by a pressing tool, which may be any suitable metalworking tool known in the art.

[0039] Referring to FIG. 5, an illustration of a plate package is shown, but it is not manufactured by the method according to the present invention. The radius r constrains the fin 32 to be positioned closer to the inner surface 42 of the flanks 4a, 4b. Therefore, a large bypass gap 30 exists. FIG. 5 further shows that the gap 30 formed between the inner surface 42 of the flank portion 4b and the outermost portion 38 of the fin 32 has a first distance d1 between the inner surface 42 of the flank 4b and the outermost fin 38 at the midpoint MH of the total height of the flow channel 12. FIG. 5 also shows distance d2, which refers to the distance between two adjacent fins 32 along the lateral extension T of the fin plate. Distance d1 is greater than distance d2. In FIG. 5, because the radius is significantly larger, the distance d1 between the outermost fin 38 and the inner surface of the flank 42 measured at the midpoint MH of the height is significantly larger.

[0040] FIG. 6 shows a variation of the plate package in which the radius (r) of the rounded corners is minimized. FIG. 6 shows a plate package manufactured by the method according to the present invention, in which the corresponding distance d1 between the inner surface 42 of the flank 4b and the outermost fin 38 at the midpoint MH of the total height of the channel 12 is smaller than the distance d2 between the two fins 32. The first distance (d1) between the inner surface 42 of the flank 4b and the outermost fin 38 closest to the flank 4b is adjusted to be equal to or smaller than the second distance (d2) between the two adjacent fins 32. Alternatively, the first distance d1 can be adjusted to be smaller than the height (h) of the channel 12. In FIG. 5, the distance d1 is larger than in FIG. 6, whereas in FIG. 6, the distance d1 at the midpoint MH of the channel height is minimized to be less than 0.5h.

[0041] Alternatively or additionally, the hydraulic diameter dh can be used as a criterion for adjusting the gap size such that the first hydraulic diameter (dh1) between the inner surface of the flank and the outermost part of the fin closest to the flank is no more than twice the second hydraulic diameter (dh2) between two adjacent fins.

[0042] Hydraulic diameter means quarter, dh=4A / P, where: A = cross-sectional area of ​​flow (A), P = wetted perimeter of the cross section.

[0043] That is, the quota is between the cross-sectional area of ​​the flow (A) and the P wetted perimeter of the cross section (P). This quota applies when the flow path is non-circular, as in the present application.

[0044] Further referring to Figures 7a-7d, different types of fin cuts are shown. Figure 7a shows a conventionally used fin cut, which is also shown in Figures 5 and 6. A disadvantage of this cut is that the radius of curvature of the flank 4b constrains the position of the outermost fin 38 relative to the inner surface 42 of the flank. According to the present application, the outermost fin 38 can be cut in conjunction with step (ii), which includes providing the fin plate 3. The fin wall 36 of the outermost fin 38 is then cut to a height lower than the height of the flow passage 12. In Figure 7b, the height is approximately 0.5h, and the fin is open toward the heat exchange portion 14 of the plate 4. Open means that the fin has its peak p where it contacts the next plate 4', and the outermost portion 38 does not have a valley where it contacts the previous plate 4. In Figures 7c and 7d, the height can be even shorter, less than 0.25h or less than 0.1h, and the fin is open toward the heat exchange portion 14 of the plate 4. Figure 7d, where the height is less than 0.25h and close to the peak of the fin, provides the optimum fin cut when attempting to minimize bypass voids.

[0045] Referring again to FIGS. 5 and 6, both of which show a schematic representation of the plate package prior to permanent bonding of the package. The pressing of the flank portions 4a, 4b of the flat plate 4 may be adjusted so that a rounded corner portion 44 with a radius (r) is provided as a transition between the heat exchange portion 14 and each of the flank portions 4a, 4b. This adjustment can therefore be achieved by adjusting the radius r. The bending radius r is larger in FIG. 5 than in FIG. 6. FIG. 6 shows a variant of the plate package 2 obtained by this method. The adjustment of the radius (r) can be performed in step i) as described above in the general description of the invention. For example, step i) can further include adjusting the radius (r) so that the distance (d1) between the inner surface of the flank portion 4b and the outermost fin 38 closest to the flank portion 4b is less than the height (h) of the flow passage 12 at the midpoint (MH) of the height (h), preferably less than 0.5h. Alternatively, minimization is performed so that the radius (r) is less than twice the thickness (d4) of the plate 4, and preferably less than 1.1 times the thickness (d4) of the plate 4. In some cases, the radius may be approximately 1 / 5 of the thickness of the plate.

[0046] The method further includes permanently joining flank portions 4a, 4b and 4a', 4b' of adjacent flat plates 4, 4' to provide a plate package 2. The permanent joining may be performed by applying a melt-suppressing composition to the heat transfer plates before they are heated, by brazing, or by bonding using the material of the heat transfer plates. The present invention also relates to a plate heat exchanger 1 including a plate package 2 manufactured by the above-described method.

[0047] Referring to FIG. 8, a schematic diagram of a plate package 2 obtained by the present method is shown. The illustration is a cross-sectional view in the XX plane as shown in FIG. 1, similar to FIG. 2. The package 2 comprises a plurality of flat plates 4, 4' and a plurality of fin plates 3, each of which has peripheral flank portions 4a, 4a' (4b and 4' are not shown) on two opposing longitudinal sides of the respective plate. Each flank portion 4a, 4a' is permanently joined to the flank portion of an adjacent flat plate 4 so that longitudinally extending flow passages 12 are formed between adjacent flat plates 4, 4'. Each flat plate 4, 4' comprises a heat exchange portion 14, which has a lateral extension between the peripheral flank portions 4a and 4b, and 4a' and 4b'. The fin plate 3 comprises a plurality of longitudinally extending fins 32 arranged within the heat exchange portion 14 of the flow passages 12 between adjacent flat plates 4. The fins 32 form transversely parallel guide channels 34 for the first heat exchange medium 18 and the second heat exchange medium 22, respectively. Essentially as described above, a first distance (d1) between the inner surface 42 of the flank portion and the outermost fin 38 closest to the flank portion at the level of the mid-height MH of the flow channel 12 is minimized.

[0048] As explained in relation to Figures 7a to 7d, the length of the fin wall 36 of the outermost fin 38 may be less than the height h of the flow passage 12. The fins 32 may be open towards the heat exchange portion 14 of the flat plate 4, as indicated in the drawings by reference numeral 38C. This allows for a smaller bypass gap when assembling and manufacturing the plate package according to the present invention, as shown in Figure 8, compared to Figure 2.

[0049] Those skilled in the art will understand that the present invention is not limited to the above examples. Those skilled in the art will further understand that modifications, combinations, and variations are possible within the scope of the appended claims. Furthermore, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. [Explanation of symbols]

[0050] 1. Plate and fin heat exchanger 2 Plate Package 3 Fin Plate 4 flat plate 4' Next plate 4a, 4b, 4a', 4b' peripheral flank parts 5a, 5b edge part 12 Flow path 14 Heat exchange part 16a, 16b inlet ports 18 First heat exchange medium 22 Second heat exchange medium 20a, 20b outlet ports 30 Bypass gap 32 Finn 34 Guide channel 36 Fin Wall 38 outermost part of fin 38C Open fin 42 Frank's Inside Story 44 Rounded Corners A Cross-sectional area of ​​the flow H Height L Longitudinal direction MH Midpoint of channel height P: Wetted perimeter of cross section T horizontal direction d1 First distance d2 Second distance dh1 First hydraulic diameter dh2 Second hydraulic diameter p-wave peak r radius t Wave trough

Claims

1. A method for assembling a plate package of a plate-and-fin heat exchanger (1), said plate package comprising: a plurality of flat plates (4, 4') and a plurality of fin plates (3), each flat plate (4, 4') having peripheral flank portions (4a, 4b, 4a', 4b') on two opposite longitudinal sides of the respective said plate; each flank portion is permanently joined to an adjacent flat plate (4') so as to define longitudinally extending channels (12) between adjacent flat plates (4, 4'), each flat plate (4, 4') comprising a heat exchange portion (14) having a lateral extension between said peripheral flank portions (4a, 4b, 4a', 4b'); the fin plate (3) comprises a plurality of longitudinally extending fins (32) disposed within the heat exchange portion (14), the fins (32) forming transverse parallel guide channels (34) for the first heat exchange medium (18) and the second heat exchange medium (22), respectively, the fin plate (3) and the flat plates (4, 4') being permanently attached to each other, comprising a plurality of flat plates (4, 4') and a plurality of fin plates (3); The method comprises: i) providing a flat plate (4) with peripheral flank portions (4a, 4b) on opposite longitudinal sides of said plate, said flank portions defining said heat exchange portion (14) of said plate; ii. Providing a fin plate (3) having longitudinally extending fins (32), said fin plate having a lateral extension greater than the lateral extension of said heat exchange portion (14) of said flat plate (4); iii) pressing the opposite sides of the fin plate (3) laterally towards each other so that the fin plate fits between the flank portions (4a, 4b) and onto the heat exchange portion (14) of the flat plate; iv) placing the next flat plate (4') of the plate package on the preceding fin plate (3) in the plate package so that at least a portion of the next flat plate (4') contacts the fins (32) of the fin plate (3) fitted to the heat exchange portion (14) of the preceding flat plate (4) and the flank portions (4a, 4b) of the preceding flat plate (4) are connected to the flank portions (4a', 4b') of the next flat plate (4'); v. Repeating steps i) to iv) until the number of fin plates in the plate package reaches a target number; vi) permanently joining said flat plate with said flank portions to said fin plate.

2. 2. The method according to claim 1, wherein in step iv) the flank portions (4a, 4b) of the flat plate (4) are connected to the flank portions (4a', 4b') of the next flat plate (4') so that they overlap in the height direction of the plate package.

3. 3. The method according to claim 1 or 2, wherein the heat exchange portion (14) of the flat plate (4) transitions to the flank portions (4a, 4b) via rounded corner portions (44) on each side of the flat plate (4), and wherein in step iii) pressing the flank portions (4a, 4b) comprises minimizing the radius (r) of the rounded corner portions (44).

4. 4. The method according to claim 3, wherein step iii) further comprises minimizing the radius (r) so that it is smaller than the height (h) of the channel, preferably less than 0.5h, and / or so that it is smaller than twice the thickness of the plate (4), preferably less than 1.1 times the thickness (d4) of the plate (4), and / or so that a distance (d1) between the inner surface (42) of the flank portions (4a, 4b) and the outermost part (38) of the fin (32) closest to the flank portions (4a, 4b) is smaller than the height (h) of the channel (12), preferably less than 0.5h.

5. 5. The method according to claim 1, wherein in step iii), the pressing step comprises adjusting a first distance (d1) measured at a midpoint (MH) of the height of the flow channel (12) between an inner surface (42) of the flank portion (4a, 4b) and an outermost part (38) of the fin (32) closest to the flank portion (4a, 4b) such that the first distance (d1) is smaller than a second distance (d2) between two adjacent fins (32) or such that the first distance (d1) is smaller than a height (h) of the flow channel (12).

6. 6. The method according to claim 5, wherein the first distance (d1) is less than 0.7h, preferably less than 0.5h.

7. 7. The method according to claim 1, wherein in step iii), the pressing step comprises adjusting a first hydraulic diameter (dh1) between the inner surface (42) of the flank portion (4a, 4b) and the outermost part (38) of the fin (32) closest to the flank portion (4a, 4b) such that the first hydraulic diameter (dh1) is not more than twice a second hydraulic diameter (dh2) between two adjacent fins, measured at a point along the longitudinal extension of the fin (32) where the hydraulic diameter is smallest.

8. 8. The method according to claim 1, wherein step ii) comprises providing a fin plate (3) in which the length of the fin walls (36) of the outermost fins (38) is smaller than the height of the flow passages (12), and the fins are open towards the heat exchange portion (14) of the flat plate (4).

9. The method of claim 8, wherein the length of the fin wall (36) is less than 0.5h, or less than 0.25h.

10. 10. The method according to any one of claims 1 to 9, wherein in said step, the flank portions (4a, 4b, 4a', 4b') of the adjacent flat plates (4, 4') are permanently joined to provide a plate package (2).

11. 11. The method of claim 10, wherein the permanently joining step in step vi) is performed by applying a melt suppressing composition applied to the heat transfer plates prior to thermal bonding, by brazing, or by bonding utilizing the material of the heat transfer plates.

12. A plate-and-fin heat exchanger (1) comprising a plate package (2) comprising a plurality of flat plates (4, 4') and a plurality of fin plates (3), each flat plate (4, 4') having peripheral flank portions (4a, 4b, 4a', 4b') on two opposite longitudinal sides of the respective flat plate, each flank portion being permanently joined to an adjacent flat plate (4') so as to form longitudinally extending flow passages (12) between the adjacent flat plates (4, 4'), and each flat plate (4, 4') having peripheral flank portions (4a, 4b, 4a', 4b') on two opposite longitudinal sides of the respective flat plate. The fin plate (3) comprises a heat exchange portion (14) having a lateral extension between adjacent flat plates (4', 4b'), the fin plate (3) comprises a plurality of longitudinally extending fins (32) disposed between adjacent flat plates (4) in contact with the adjacent flat plates (4) in the heat exchange portion (14) of the flow path (12), the fins (32) forming lateral parallel guide channels (34) for the first heat exchange medium (18) and the second heat exchange medium (22), respectively, the heat exchange portion (14) of the flat plates (4) being disposed on each side of the flat plates (4). and transitioning to the peripheral flank portions (4a, 4b) through rounded corners (44) of the flow channel (12), such that the radius (r) of the rounded corners (44) is minimized and is smaller than the height (h) of the flow channel, preferably less than 0.5h, and / or such that the radius (r) is less than twice the thickness (d4) of the plate (4), preferably less than 1.1 times the thickness (d4) of the plate (4), and / or measured at the midpoint (MH) of the height of the flow channel (12), a first distance (d1) between the inner surface (42) of the peripheral flank portion and the outermost fin (38) is smaller than a second distance (d2) between two adjacent fins (32), and / or the first distance (d1) is smaller than a height (h) of the flow passage (12), the length of the fin wall (36) of the outermost fin (38) is smaller than the height of the flow passage (12), and the fin (32) is pressed so that it opens toward the heat exchange portion (14) of the flat plate (4).

13. 13. The heat exchanger of claim 12, wherein a first hydraulic diameter (dh1) between the inner surface (42) of the flank portion (4a, 4b) and the outermost part (38) of the fin closest to the flank portion is not more than twice a second hydraulic diameter (dh2) between two adjacent fins, measured at a point where the hydraulic diameter is smallest along the longitudinal extension of the fin (32).

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