Heat exchanger having indentations for avoiding stagnant media

Abstract

A brazed plate heat exchanger (10) comprises end plates (11) and a stack of heat exchanger plates (12, 12a, 12b), the stack of heat exchanger plates being provided with a pattern comprising ridges (R) and grooves (G), the ridges and grooves being adapted to form contact points (16) between adjacent heat exchanger plates such that the heat exchanger plates form inter-plate flow channels for media to exchange heat on the heat exchanger plates, the heat exchanger plates further being provided with port openings (O1 - O4) for selective fluid communication with the flow channels, wherein the port openings are surrounded by port opening regions (13) for sealing corresponding port opening regions of adjacent heat exchanger plates, wherein adjacent heat exchanger plates are connected by brazed joints at the contact points (16), wherein the end plates (11) are provided with port openings (O1 - O4) and flat regions (14) surrounding the port openings in a common plane, wherein indentations (15) are formed in regions of a plurality of ridges (R) of the heat exchanger plates that overlap any of the flat regions (14) of the end plates (11), wherein the indentations (15) of the heat exchanger plates (12, 12a) adjacent to the end plates (11) connect the flow channels formed between the end plates and the adjacent heat exchanger plates (12, 12a) to adjacent flow channels to allow media to be distributed between the flow channels. The brazed joints for connecting adjacent heat exchanger plates are arranged between at least one of the port opening regions (13) and the indentations (15).

Description

Field of the Invention

[0001] The present invention relates to a heat exchanger having indentations for avoiding stagnant media. More specifically, the present invention relates to a brazed plate heat exchanger comprising end plates and a stack of heat exchanger plates, the stack of heat exchanger plates being provided with a pattern including ridges and grooves adapted to form contact points between adjacent heat exchanger plates such that the heat exchanger plates form inter-plate flow channels for media to exchange heat on the heat exchanger plates. The heat exchanger plates are further provided with port openings for selective fluid communication with the flow channels, wherein the port openings are surrounded by port opening regions so as to seal the corresponding port opening regions of adjacent heat exchanger plates. Adjacent heat exchanger plates are connected by a brazed joint at the contact points. The end plates are provided with port openings and a flat region surrounding the port openings in a common plane. In a region overlapping with the flat region of the end plate, a plurality of ridges of the heat exchanger plates are formed with indentations, wherein the indentations of the heat exchanger plates adjacent to the end plate connect the flow channel formed between the end plate and the adjacent heat exchanger plate with adjacent flow channels to allow distribution of the media therebetween. Background Art

[0002] When exchanging heat between different media in any type of heat exchanger, it is generally advantageous to avoid stagnant media, i.e., media that do not follow the overall flow path but remain stationary. Stagnant media are cumbersome for many reasons: Bacterial or microbial growth may occur in stagnant areas, and the media may freeze, thus damaging the heat exchanger. In addition, the overall efficiency of the heat exchanger may be hindered. For a brazed plate heat exchanger comprising a pressed pattern of ridges and grooves that keep the heat exchanger plates at a certain distance from each other, a historically critical area for forming stagnant media is between the end plate having a flat region near the port opening and the adjacent heat exchanger plate, where the end plate forms a dead-end flow channel in which the media easily stagnates between the end plate and the adjacent heat exchanger plate.

[0003] EP0857288 solves the problem of stagnant media in the space between the flat region of the end plate and the adjacent heat exchanger plate by providing a distribution channel between the flow channel and the adjacent flow channel, which would otherwise be a dead-end flow channel. The distribution channel allows the flow that would otherwise "get stuck" in the dead-end flow channel. The distribution channel of EP0857288 is provided adjacent to the port opening region, i.e., at the very end of the ridge. Although the solution disclosed in this patent is effective for avoiding stagnant media, it has some disadvantages when it comes to strength.

[0004] Therefore, a problem with prior art heat exchangers is that they are not durable and cannot withstand high pressures. Summary of the Invention

[0005] The object of the present invention is to provide a brazed plate heat exchanger which has a reduced risk of stagnant media while increasing the number of contact points between the ridges and grooves of adjacent plates around the port opening area and thus increasing the strength of the heat exchanger.

[0006] The present invention relates to a brazed plate heat exchanger which comprises end plates and a stack of heat exchanger plates, the stack of heat exchanger plates being provided with a pattern comprising ridges and grooves adapted to form contact points between adjacent heat exchanger plates such that the heat exchanger plates form inter-plate flow channels for a medium to exchange heat on the heat exchanger plates, the heat exchanger plates further being provided with port openings for selective fluid communication with the flow channels, wherein the port openings are surrounded by a port opening area for sealing the corresponding port opening areas of adjacent heat exchanger plates, wherein adjacent heat exchanger plates are connected at said contact points by brazed joints, wherein the end plates are provided with port openings and a flat area surrounding the port openings in a common plane, wherein a plurality of ridges of the heat exchanger plates are formed with indentations in an area overlapping any of said flat areas of the end plates, wherein said indentations of the heat exchanger plates adjacent to the end plates connect the flow channels formed between the end plates and the adjacent heat exchanger plates with adjacent flow channels to allow distribution of the medium between the flow channels, characterized in that the brazed joints for connecting adjacent heat exchanger plates are arranged between at least one of said port opening area and said indentations..

[0007] By providing the indentations, cross-ridge flow channels are formed for distributing the medium and preventing stagnant media in the flow channels which would otherwise be dead-end flow channels in the space between the end plate and the adjacent heat exchanger plate, the adjacent heat exchanger plate being for example the first or last heat exchanger plate in the stack. Furthermore, it has surprisingly been found that by arranging said indentations at a small distance from the very end of the flow channel, i.e. on the ridge at a certain distance from the nearest port opening area, space is provided for the contact points and thus for the brazed joints while still preventing stagnant media in the flow channels. Thus, it has been found that a favourable flow of the medium is also achieved when the brazed joints are arranged between the indentations and the port opening area. The brazed joints between the port opening area and at least some of the indentations result in a more robust heat exchanger. Moreover, contact points closer to the port opening area are achieved, which results in a smaller pressure area around the port. Additional contact points are obtained. Moreover, contact points closer to the port opening are achieved. For example, the distance between the port opening and the first row of contact points can be shorter than in the prior art and the area around the port opening exposed to the medium pressure is smaller. Moreover, a higher contact point density can be achieved in the immediate vicinity of the port opening. This together results in a strong heat exchanger while preventing stagnant media in dead-end flow channels.

[0008] The end plate can be a conventional end plate having a flat area around the port opening, for example in the end portion of a rectangular end plate. The port opening and the flat area of the end plate are arranged in a common plane. The end plate can be a front end plate or a rear end plate. The flat area of the end plate can be adapted to connect to a hydraulic block or a similar conventional fitting. The end plate can be provided with a pattern of ridges and grooves in its central portion.

[0009] Contact points can be provided on the ridges and are located on both sides of an indentation or a plurality of indentations that connect a flow channel to an adjacent flow channel, which would otherwise form a dead-end flow channel with the end plate. Thus, a very robust heat exchanger can be achieved while preventing stagnant media. Accordingly, the heat exchanger plates can be connected to each other by multiple rows of brazed joints, wherein the indentation or the plurality of indentations can be arranged between a first row of brazed joints and a second row of brazed joints counted from the port opening area closest to the indentation.

[0010] Brief Description of the Drawings

[0011] The present invention will be described below with reference to the drawings, wherein:

[0012] Figure 1 is a schematic exploded view of a heat exchanger according to a first embodiment of the present invention,

[0013] Figure 2 is according to Figure 1 a schematic front view of a heat exchanger plate,

[0014] Figure 3 is Figure 2 a schematic front view of a heat exchanger plate, showing imaginary contact points between the shown plate and another heat exchanger plate,

[0015] Figure 4 is a schematic exploded view of a heat exchanger according to a second embodiment of the present invention,

[0016] Figure 5 is according to Figure 4 a schematic front view of a heat exchanger plate,

[0017] Figure 6 is Figure 5 a schematic front view of a heat exchanger plate, showing imaginary contact points between the shown plate and another heat exchanger plate,

[0018] Figure 7 is a schematic front view of a heat exchanger plate according to a third embodiment,

[0019] Figure 8 is Figure 7 a schematic front view of a heat exchanger plate, showing imaginary contact points between the shown plate and another heat exchanger plate,

[0020] Figure 9 and 10 is a schematic front view of a heat exchanger plate according to another embodiment of the present invention, wherein Figure 9 shows a plate, Figure 10 shows another plate arranged together in an alternating manner, and

[0021] Figure 11 is according to Figure 9 a schematic perspective view of a part of the heat exchange plate, showing the imaginary contact points between the shown plate and another heat exchange plate in two directions. Detailed Description

[0022] Referring to Figure 1 , a heat exchanger 10 according to an embodiment of the present invention is schematically shown. The heat exchanger 10 includes end plates 11 and a plurality of heat exchanger plates 12 stacked in a stack to form the heat exchanger 10. In Figure 1 the embodiment, the heat exchanger plates 12 are identical.

[0023] The heat exchanger plates 12 are made of metal sheets and are provided with a pattern of ridges R and grooves G such that when the plates are stacked in a stack to form the heat exchanger 10, by providing contact points between at least some of the intersecting ridges and grooves of adjacent plates 12, in the case of forming an inter-plate flow channel for fluid to exchange heat, an inter-plate flow channel for fluid to exchange heat is formed between the plates. According to Figures 1-3 the embodiment, the pattern is a herringbone pattern. However, as described below, the pattern can also be in the form of straight lines extending obliquely. The pattern of ridges R and grooves G is a corrugated pattern with a corrugation depth. The pattern is a pressed pattern. The pattern is adapted to keep the plates 12 at a certain distance from each other except at the contact points to form a space between adjacent heat exchanger plates and flow channels.

[0024] In the shown embodiment, each heat exchanger plate 12 is surrounded by a skirt S that extends substantially perpendicular to the plane of the heat exchanger plate 12 and is adapted to contact the skirts of adjacent plates 12 to provide a seal along the perimeter of the heat exchanger 10.

[0025] The heat exchanger plates 12 are provided with port openings O1 - O4 for allowing fluid to exchange heat in and out of the inter-plate flow channel. In the shown embodiment, the end plates 11 and the heat exchanger plates 12 are arranged with four port openings O1 - O4. In Figure 1In [the heat exchanger], some port openings are missing, which is understood by those skilled in the art and does not affect the disclosure of the present invention. The port opening regions 13 around the port openings O1 to O4 are arranged at different heights, i.e., different levels, so as to achieve selective communication between the port openings and the inter-plate flow channels. For example, the port opening regions 13 are flat. The port opening regions 13 are arranged to seal the corresponding port opening regions 13 of adjacent heat exchanger plates 12. For example, the port openings O1 - O4 and the port opening regions 13 are arranged in a conventional manner.

[0026] In Figure 1 the heat exchanger 10, the port opening regions 13 are arranged such that the first port opening O1 and the second port opening O2 are in fluid communication with each other through the inter-plate flow channels, while the third largest port opening O3 and the fourth largest port opening O4 are in fluid communication with each other through the adjacent inter-plate flow channels. In the illustrated embodiment, the heat exchanger plates 12 are rectangles with rounded corners, where the port openings O1 - O4 are arranged near the corners. Alternatively, the heat exchanger plates 12 are square, for example with rounded corners. Alternatively, the heat exchanger plates 12 are circular, oval or arranged in other suitable shapes, where the large port openings O1 - O4 are distributed in a suitable manner. In the illustrated embodiment, each heat exchanger plate 12 is formed with four port openings O1 - O4. Alternatively, the heat exchanger plates 12 are formed with other numbers of ports, such as six, eight or ten. In Figure 1 the embodiment, the heat exchanger plates 12 are the same, and every other plate 12 is rotated 180 degrees in its plane relative to the adjacent heat exchanger plates 12.

[0027] According to Figure 1 the end plates 11 are formed with flat regions 14 having the port openings O1 - O4. The port openings O1 - O4 of the end plates 11 are aligned with the port openings of the heat exchanger plates 12 in a conventional manner. For example, the end plate 11 includes a first end having a first flat region and adjacent port openings O1 and O3, and a second end having a second flat region and adjacent port openings O2 and O4. For example, the end plate 11 is a conventional end plate. In the illustrated embodiment, the end plate 11 includes a central portion having a pattern of ridges (R) and grooves (G) similar to those of the heat exchanger plates 12. The ends do not have the pattern of ridges and grooves. Instead, the ends are formed with flat regions 14, at least around the port openings O1 - O4. The port openings O1 - O4 and the flat regions 14 are arranged in a common plane. Thus, the flat regions 14 of the end plate 11 and the grooves (G) of the adjacent heat exchanger plates 12 (such as the first heat exchanger plate in the heat exchanger plate stack) form flow channels. The flat regions 14 and the adjacent heat exchanger plates 12 form flow channels near the port opening regions 13 of the adjacent heat exchanger plates 12.

[0028] When the heat exchanger plates 12 and the end plates 11 are installed to form part of the plate heat exchanger 10, two of the port opening areas 13 will contact the flat area 14 of the end plate 11. Also, the ridges R of the heat exchanger plates 12 will contact the flat area 14 of the end plate 11. Thus, flow channels are formed between the flat area 14 at the end of the end plate 11 and the adjacent heat exchanger plates 12. Flow channels are formed in the area between adjacent port openings of the heat exchanger plates 12. For example, flow channels are formed between the flat area 14 and the adjacent heat exchanger plates 12 through grooves G connected to the first port opening O1, where the grooves (G) terminate when some of the grooves G reach the port opening area 13 around the adjacent third port opening O3.

[0029] Also refer to Figure 2 , the heat exchanger plates 12 are provided with indentations 15. The indentations 15 are arranged to provide cross-ridge flow channels. The indentations 15 are arranged in the ridges R of the heat exchanger plates 12, where at least some of the ridges are formed with at least one indentation 15. At least some of the indentations 15 are arranged near the port openings O3, O4 to connect the grooves G that will form flow channels together with the flat area 14, thereby preventing stagnant media in the flow channels between the heat exchanger plates 12 and the flat area 14 of the end plate 11. By providing the indentations 15, dead-end flow channels defined by the ridges R and the flat ends 14 of the end plate 11 are avoided. The indentations 15 are set to have a depth corresponding to at least 5% of the corrugation depth of the heat exchanger plates 12. For example, the depth of the indentations 15 is less than 80% of the corrugation depth. For example, the depth of the indentations 15 is 20 - 80%, 40 - 80%, 50 - 60% or 50% of the corrugation depth.

[0030] Refer to Figure 3 , the contact points 16 between the heat exchanger plate 12 and another heat exchanger plate are schematically shown. Generally, brazed joints are arranged in the contact points 16, where the contact points 16 correspond to the brazed joints. For example, each contact point 16 between adjacent heat exchanger plates 12 corresponds to a brazed joint. In Figure 3 , the contact points 16 are shown on the rear side of the heat exchanger plate 12, and those skilled in the art understand that the contact points 16 with adjacent heat exchanger plates on the front side are at corresponding positions on the ridges R, as schematically shown by several squares near the third port opening O3 in Figure 3 . As Figure 3As shown, at least some of the indentations 15 are arranged at a distance from the port opening regions 13 of the third port opening O3 and the fourth port opening O4, leaving a space for the brazing joint between the indentations 15 and the port openings O3, O4. Accordingly, the brazing joint for connecting the heat exchanger plate to an adjacent heat exchanger plate is arranged between the port opening region 13 and at least one of the indentations 15. A plurality of ridges R of the heat exchanger plate 12 are formed with indentations 15 in the region overlapping the flat region 14 of the end plate 11. The indentations 15 of the heat exchanger plate 12 adjacent to the end plate 11 connect the flow channels formed between the flat region 14 of the end plate 11 and the adjacent heat exchanger plate 12 to the adjacent flow channels, allowing the medium to be distributed therebetween and preventing the stagnant medium therein. Meanwhile, in the region overlapping the flat region 14 of the end plate 11, the brazing joint for connecting adjacent heat exchanger plates 12 is arranged between the port opening region 13 and at least one or more of the indentations 15 or all of them.

[0031] In Figures 1-3 the embodiment, not all of the indentations 15 of the heat exchanger plate 12 are arranged in the immediate vicinity of the port openings O3, O4. For example, every other indentation 15 is arranged at a significant distance from the port openings O3, O4. For example, at least one indentation 15 or a plurality of indentations 15 are arranged at a distance from the nearest port opening region 13 corresponding to the brazing joint, where the indentation 15 is arranged adjacent to the brazing joint between the indentation 15 and the port opening region 13. For example, more indentations 15 are arranged near the port opening region 13 around the fourth port O4 than near the port opening region 13 around the third port O3.

[0032] Referring to Figures 4-6 , a second embodiment of the heat exchanger 10 is shown, where the end plate 11 is similar to the end plate described with reference to Figure 1 and some of the port openings understood by those skilled in the art are omitted in Figure 4 . In Figures 4-6 the embodiment, the heat exchanger plates 12 are identical and provided with a herringbone pattern of ridges R and grooves G, where every other heat exchanger plate 12 is rotated 180 degrees in its plane.

[0033] Also referring to Figure 5 , the heat exchanger plate 12 is provided with a plurality of indentations 15 that form cross-ridge channels and connect adjacent grooves G. In the shown embodiment, the indentations 15 are arranged near and at a distance from the port openings O3, O4 in the ridges R of the heat exchanger plate 12 to connect adjacent grooves G and prevent the stagnant medium in the flow channels formed between the flat region 14 and the adjacent heat exchanger plate 12. In Figures 4-6In an embodiment, all ridges R in the region between the first port opening 1 and the third port opening O3 are provided with indentations 15, which leave space for the contact points 16, and thus a brazed joint between the port opening regions 13 of the third and fourth port openings O3, O4 and each indentation 15 schematically shown as in Figure 6 Likewise in Figure 6 a contact point 16 is schematically shown between the heat exchanger plate 12 and another heat exchanger plate behind the heat exchanger plate, wherein the contact point 16 on the front side facing the other heat exchanger plate 12 is understood by a person skilled in the art to be at a corresponding position on the ridge R, as schematically shown by several squares near the third port opening O3 in Figure 6 As can be seen in Figure 6 the indentations 15 are arranged at a certain distance from the port opening regions 13 of the third port opening O3 and the fourth port opening O4, thus leaving space for the brazed joint between the indentations 15 and the port openings O3, O4. Therefore, a brazed joint is arranged between the port opening region 13 and the indentation 15.

[0034] In Figures 4-6 the embodiment, all indentations are provided between the contact points 16, except for one indentation 15 at each end of the plate. Therefore, most of the indentations 15 are arranged between the contact points 16. For example, at least four or at least five indentations 15 are arranged near the third port opening O3, while more indentations 15, for example at least six or seven, are arranged near the fourth port opening O4. In Figures 4-6 the embodiment, the indentations 15 near the third port opening O3 are arranged in a straight line along the longitudinal direction of the heat exchanger plate 12, for example parallel to the longitudinal center line of the plate. For example, the indentations 15 form a continuous cross-ridge flow channel between the first and the last indentation 15 in a row of indentations 15. For example, the indentations 15 near the fourth port opening O4 are arranged in a corresponding manner, optionally with additional indentations 15 deviating from the straight line. For example, the heat exchanger plates 12 are connected to each other by multiple rows of contact points 16, wherein a plurality of indentations 15 are arranged between the first and the second row of contact points 16 counted from the nearest port opening region 13. Therefore, the indentations 15 are arranged outside the first row of contact points 16. For example, a row of indentations 15 forming a continuous cross-ridge flow channel is arranged outside the first row of contact points 16.

[0035] Referring to Figure 7 and 8 the heat exchanger plate 12 is provided with a plurality of indentations 15, which form a cross-ridge channel in another pattern, wherein a plurality of indentations 15 are distributed between the first port opening O1 and the third port opening O3 between the contact points 16. In Figure 7 and 8In an embodiment, a greater number of indentations 15 are distributed in a similar pattern over a larger area between the second port opening O2 and the fourth port opening O4. For example, the pattern of the indentations 15 is a regular pattern.

[0036] Referring to Figure 9 and 10 , another embodiment of the present invention is shown, in which Figure 9 a first type of heat exchanger plate 12a is shown, Figure 10 and a second type of heat exchanger plate 12b is shown. The first and second types of heat exchanger plates 12a, 12b are alternately stacked and provided with end plates 11 to form a heat exchanger 10. The first and second types of heat exchanger plates 12a, 12b are provided with a pattern of ridges R and grooves G in a straight line form with an inclined extension. Thus, Figure 9 and 10 the heat exchanger 10 in the embodiment of Figure 9 and 10 includes two different types of heat exchanger plates 12a, 12b having a pattern of ridges R and grooves G forming inter-plate flow channels, wherein the flow channels are formed between adjacent heat exchanger plates 12a in the area between the flat area 14 of the end plate 11 and the port openings O1 - O4, and the adjacent heat exchanger plates 12a are of the first type. At least the first type of heat exchanger plate 12a is provided with indentations 15 forming cross-ridge flow channels to prevent dead-end flow channels between the flat area 14 of the end plate and the adjacent heat exchanger plates 12a. In

[0037] Referring to Figure 11 , contact points 16 are schematically shown on a part of the first type of heat exchanger plate 12a, and thus a brazed joint is schematically shown. The contact points 16 are shown for both sides of the plate 12a. Thus, as Figure 11As shown, the indentations 15 or at least most of them near the port openings O1 - O4 are arranged between the contact points 16. Thus, contact points 16 are provided between the port opening region 13 and the nearest indentation 15, thereby forming a cross - ridge channel connecting adjacent slots G in the region where the connection overlaps the flat region 14, wherein another contact point 16 is arranged on the ridge R on the other side of the same indentation 15. For example, the contact points 16 between adjacent heat exchanger plates 12 are arranged immediately before and after the indentation 15 in the region overlapping the flat region 14 of the end plate 11, thereby connecting the flow channels and adjacent flow channels. Thus, the indentation 15 of the heat exchanger plate 12a adjacent to the end plate 11 connects the flow channel between the flat region 14 of the end plate 11 and the adjacent heat exchanger plate 12a to the adjacent flow channel to allow the distribution of the medium between them and prevent stagnant medium therein, while the brazed joint is arranged between the adjacent heat exchanger plates 12a, 12b at the position between the port opening region 13 and the indentation 15 to provide a robust heat exchanger 10.

Claims

1. A brazed plate heat exchanger (10) comprising end plates (11) and a stack of heat exchanger plates (12, 12a, 12b), the stack of heat exchanger plates being provided with a pattern comprising ridges (R) and grooves (G), the ridges and grooves being adapted to form contact points (16) between adjacent heat exchanger plates such that the heat exchanger plates form inter-plate flow channels for media to exchange heat on the heat exchanger plates, the heat exchanger plates further being provided with port openings (O1 - O4) for selective fluid communication with the flow channels, wherein the port openings are surrounded by port opening regions (13) for sealing corresponding port opening regions of adjacent heat exchanger plates, wherein adjacent heat exchanger plates are connected by brazed joints at the contact points (16), wherein the end plates (11) are provided with port openings (O1 - O4) and a flat region (14) surrounding the port openings in a common plane, wherein indentations (15) are formed in regions of a plurality of ridges (R) of the heat exchanger plates that overlap any of the flat regions (14) of the end plates (11), wherein the indentations (15) of the heat exchanger plates (12, 12a) adjacent to the end plate (11) connect the flow channels formed between the end plate and the adjacent heat exchanger plates (12, 12a) to adjacent flow channels to allow media to be distributed between the flow channels, It is characterized in that The brazed joints for connecting adjacent heat exchanger plates are arranged between at least one of the port opening regions (13) and the indentations (15), wherein the contact points (16) are arranged on the ridges (R) and on both sides of at least one of the indentations (15), and the indentations (15) connect the flow channels formed between the end plate (11) and the adjacent heat exchanger plates (12, 12a) to adjacent flow channels to allow media to be distributed between the flow channels.

2. The brazed plate heat exchanger according to claim 1, wherein, The heat exchanger plates are connected to each other by multiple rows of brazed joints, wherein a plurality of indentations (15) are arranged between a first row of brazed joints and a second row of brazed joints when counted starting from the closest port opening region (13).

3. The brazed plate heat exchanger according to claim 1, wherein, The brazed joints for connecting adjacent heat exchanger plates are arranged adjacent to the indentations.

4. The brazed plate heat exchanger according to claim 1, wherein, The heat exchanger plates are formed with indentations (15) for connecting at least every other flow channel formed between the end plate (11) and the adjacent heat exchanger plates (12, 12a) to adjacent flow channels to allow media to be distributed between the flow channels.

5. The brazed plate heat exchanger according to claim 1, wherein, The pattern comprising ridges (R) and grooves (G) has a corrugation depth, and wherein the indentations (15) are formed with a depth corresponding to at least 5% of the corrugation depth.

6. The brazed plate heat exchanger according to claim 5, wherein, The depth of the indentations is 30 - 80% of the corrugation depth.

7. The brazed plate heat exchanger according to claim 6, wherein, The depth of the indentations is 40 - 60% of the corrugation depth.

8. The brazed plate heat exchanger according to claim 7, wherein, The depth of the indentations is 50% of the corrugation depth.

9. The brazed plate heat exchanger according to claim 1, wherein, The end plate (11) is formed with a pattern of ridges and grooves in its central portion.

10. The brazed plate heat exchanger according to claim 1, wherein, The port opening regions (13) of the heat exchanger plates are arranged at different levels.

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