Double wall plate heat exchanger

Abstract

A double wall plate heat exchanger (100) comprising a plurality of double wall plate heat exchanger elements (110, 120) formed with ridges (R) and grooves (G) providing contact points between adjacent heat exchanger elements (110, 120) forming flow channels between adjacent heat exchanger elements for fluid to exchange heat. The flow channels are selectively in fluid communication with each other through port openings. Each heat exchanger element (110, 120) comprises at least two connected plates and a leakage channel is formed between the plates of each heat exchanger element (110, 120) for fluid to leak from the flow channels. The plates are provided with cooperating protrusions (190) and recesses (200) to form the leakage channel (210) extending across the ridges and grooves between the plates of each heat exchanger element (110, 120). At least one connection space is formed between the plates to connect the leakage channels within the same heat exchanger element (110, 120) and each connection space is connected to a leakage outlet.

Description

Technical Field

[0001] This invention relates to a double-walled plate heat exchanger. More specifically, the invention relates to a double-walled plate heat exchanger comprising a plurality of double-walled plate heat exchanger elements, wherein the double-walled plate heat exchanger elements are formed with ridges and grooves, and in the case where flow channels for fluid heat exchange are formed between the double-walled plate heat exchanger elements, the ridges and grooves provide contact points between at least some intersecting ridges and grooves of adjacent double-walled plate heat exchanger elements, the flow channels being selectively fluidly connected to each other through port openings of the double-walled plate heat exchanger elements, wherein each double-walled heat exchanger element comprises two plates, wherein the plates are formed with ridges and grooves to form a pattern of ridges and grooves of the double-walled heat exchanger element, and wherein leakage channels are formed between the plates of each double-walled plate heat exchanger element for fluid leakage from the flow channels.

[0002] Double-walled plate heat exchangers are typically used to prevent one fluid from leaking into another within the heat exchanger. For example, such heat exchangers can be used in heat exchange applications involving fluids intended for human consumption, such as liquid foods, or fluids that, when mixed, might cause undesirable chemical reactions. Double-walled plate heat exchangers are also useful when it is necessary to detect leaks from one fluid into another. Background Technology

[0003] Various types of brazed double-walled plate heat exchangers can be found in the prior art. As is known to those skilled in the art, such heat exchangers include multiple double-walled heat exchanger elements formed by two connected plates, wherein the plates are formed with ridges and grooves to form a pattern of ridges and grooves of the double-walled heat exchanger elements, and wherein leakage channels are formed between the plates of each double-walled plate heat exchanger element to collect fluid leaking from the flow channels and guide it to the periphery of the plates.

[0004] One problem with existing double-walled plate heat exchangers is that they can be inefficient and unreliable.

[0005] Another problem with this existing double-walled plate heat exchanger is that leaks are difficult to detect.

[0006] Another problem with these existing double-walled heat exchangers is that they are difficult and complex to manufacture. Summary of the Invention

[0007] The purpose of this invention is to overcome or at least mitigate the above-mentioned problems, and to provide a reliable and effective double-walled plate heat exchanger that is easy to manufacture and has convenient leak detection.

[0008] This invention relates to a double-walled plate heat exchanger comprising a plurality of double-walled heat exchanger elements, wherein the double-walled heat exchanger elements are formed with a pattern of ridges and grooves to provide contact points between at least some intersecting ridges and grooves of adjacent heat exchanger elements, flow channels for fluid heat exchange are formed between the double-walled heat exchanger elements, the flow channels being selectively fluidly connected to each other through port openings of the double-walled heat exchanger elements, wherein each double-walled heat exchanger element comprises at least two connected plates, wherein the plates are formed with ridges and grooves to form a pattern of ridges and grooves of the double-walled heat exchanger elements, and wherein leakage channels are formed between the plates of each double-walled plate heat exchanger element for fluid leakage from the flow channels, characterized in that the plates are provided with protrusions and recesses for mating to form the leakage channels, the leakage channels extending across the ridges and grooves between the plates of each double-walled heat exchanger element, at least one connecting space is formed between the plates of each double-walled heat exchanger element, the connecting space connecting to the leakage channels within the same double-walled heat exchanger element, and the connecting space connecting to a leakage outlet. The combination of the leakage channels spanning the ridges and grooves with the connecting spaces connecting these channels allows leaked fluid to be collected efficiently, for example, guided toward a single or several leak outlets at one or more desired locations, where leak detection can be facilitated. Thus, the connecting spaces can be connected to defined leak areas, whereas prior art leaks are undefined or spread out. The leakage channels connected to the connecting spaces according to the invention also allow for the efficient and reliable manufacture of double-walled heat exchangers via brazing, as the brazing material can be applied simply and blockages can be avoided. The leakage channels can be made relatively narrow to provide efficient heat transfer.

[0009] Connection spaces can extend along the ridges and / or grooves of the plate. Thus, leakage channels arranged across the ridges and grooves are connected to each other via connection spaces extending along the ridges and / or grooves, where fluid from any leakage channel can reach one or more leakage outlets through the connection spaces. Connection spaces can be formed by ridges with a height lower than the corresponding ridges of adjacent plates, where the connection spaces are formed between lower ridges (or similar grooves) received in the higher ridge. Thus, connection spaces are formed in an efficient and reliable manner. Moreover, connection spaces can be limited to one or several to maintain high efficiency of heat exchange. Therefore, since multiple ridges and grooves can maintain a large heat exchange area, most or almost all ridges and grooves are not provided with connection spaces and are in contact with each other. Furthermore, since conventional brazing points can be provided between ridges and grooves in contact with each other in a double-walled heat exchanger element, a robust heat exchanger can be obtained.

[0010] The plate can be rectangular, with the leak outlet located on the short side. Thus, leaking fluid can be directed to a single leak outlet on the short side of the heat exchanger, further facilitating leak detection. Therefore, the long sides of the plate can be brazed together, for example in a conventional manner, such as having continuous brazed joints on the long sides, allowing the heat exchanger to be manufactured robustly and efficiently.

[0011] The plates can be provided with peripheral skirts, wherein the skirts of three consecutive plates can be provided with holes forming a common leak outlet for leak passages from two adjacent double-walled plate heat exchanger elements. For example, these holes can be aligned. The holes can be arranged along the short side of the plate. Therefore, leaks can be concentrated in one or several locations for more reliable detection, while the main periphery of the plate, such as including the entire long side, can be brazed together to provide a robust heat exchanger and efficient production.

[0012] Heat exchangers can be equipped with leak sensors, such as conventional leak sensors. The leak sensor can be positioned at the leak outlet, for example, at one or more defined locations around the heat exchanger, enabling effective and reliable leak detection. For instance, the leak sensor can be connected to the outer perimeter of the heat exchanger.

[0013] Other features and advantages of the invention will become apparent from the following description of the embodiments, the accompanying drawings, and the dependent claims. Attached Figure Description

[0014] The present invention will now be described with reference to the accompanying drawings, wherein: Figure 1 This is a schematic exploded perspective view of one embodiment of a plate heat exchanger. Figure 2 This is a schematic exploded perspective view of a plurality of double-walled plate heat exchanger elements according to one embodiment, wherein each double-walled plate heat exchanger element includes two plates. Figure 3 This is a schematic exploded perspective view of a first double-walled plate heat exchanger element and a second double-walled plate heat exchanger element according to one embodiment, wherein the first double-walled plate heat exchanger element includes a first plate and a second plate, and wherein the second double-walled plate heat exchanger element includes a third plate and a fourth plate. Figure 4 yes Figure 3 A schematic front view of a double-walled heat exchanger element. Figure 5 It is along Figure 4 The schematic cross-sectional view of line AA in the diagram shows the flow channels between the elements of the double-walled heat exchanger and the leakage channels in each element. Figure 6 It is along Figure 4The schematic cross-sectional view of line BB in the diagram shows a double-walled plate heat exchanger element, partially along a portion of the leakage path and partially along a portion without a leakage path. Figure 7 This is a schematic front view of the components of a double-walled plate heat exchanger. Figure 8 It is along Figure 7 A schematic cross-sectional view of line CC in the diagram shows the connection space along the two ridges and two slots according to one embodiment, and... Figure 9 This is a schematic exploded perspective view of a portion of a double-walled plate heat exchanger element according to one embodiment. Detailed Implementation

[0015] Reference Figure 1 An example of a brazed plate heat exchanger 100 is shown according to one embodiment. The heat exchanger 100 includes a plurality of first plate heat exchanger elements 110 and a plurality of second plate heat exchanger elements 120 stacked together to form the heat exchanger 100. For example, the heat exchanger elements 110, 120 are identical. Alternatively, the heat exchanger elements are not identical, wherein the heat exchanger 100 includes at least two, three, or four different heat exchanger elements 110, 120. The heat exchanger 100 is a double-walled heat exchanger, wherein each heat exchanger element 110, 120 includes two plates connected together to form the heat exchanger element 110, 120, which will be described in more detail below. Thus, the first heat exchanger element 110 is a first double-walled plate heat exchanger element, and the second heat exchanger element 120 is a second double-walled plate heat exchanger element. For example, the heat exchanger 100 is a symmetrical heat exchanger. Alternatively, the heat exchanger may be an asymmetric heat exchanger, wherein the heat exchanger comprises at least two different heat exchanger elements 110, 120.

[0016] Heat exchanger elements 110 and 120 are made of metal sheets, such as copper or stainless steel, and are provided with raised and recessed embossed patterns. For example, the heat exchanger elements are made of copper or austenitic stainless steel with a thickness of 0.1 to 2 mm.

[0017] In the illustrated embodiment, when forming flow channels for fluid heat exchange, the protrusions and recesses include ridges R and grooves G, providing contact points between at least some of the intersecting ridges and grooves of adjacent heat exchanger elements 110, 120, such that when the heat exchanger elements 110, 120 are stacked together to form the heat exchanger 100, flow channels for fluid heat exchange are formed between the heat exchanger elements 110, 120. Figure 1The pressed pattern of the plates includes a herringbone pattern. The pressed pattern may include any suitable pattern or combination of patterns. The pressed pattern is adapted to maintain the heat exchanger elements 110, 120 at a distance from each other except for the contact points to form flow channels. The ridges R and grooves G are elongated. For example, the ridges R and grooves G extend at an angle between one side (e.g., its long side) and the centerline (e.g., a centerline extending between the short sides) of the heat exchanger elements 110, 120 to form a herringbone shape, wherein the ridges and grooves (e.g., at a mirror angle) continue to the opposite side (e.g., the opposite long side). For example, the ridges R and grooves G extend in a herringbone pattern between the opposite long sides, with the herringbone in the middle. Alternatively, the ridges R and grooves G extend in a sloping straight line from one long side to the opposite long side.

[0018] In the illustrated embodiment, each heat exchanger element 110, 120 is surrounded by a skirt S that extends substantially perpendicular to the plane of the heat exchanger element and is adapted to contact the skirts of adjacent heat exchanger elements 110, 120 to provide a seal along the periphery of the heat exchanger or at least its main portion. Figure 1 In one embodiment, the skirt S is arranged continuously along opposite sides of the heat exchanger elements 110, 120, for example, along the two long sides in the case of the rectangular heat exchanger shown. In the illustrated embodiment, the skirt S is also arranged continuously along one short side of the heat exchanger elements 110, 120.

[0019] Heat exchanger elements 110 and 120 are provided with port openings O1-O4 for allowing fluid to enter and exit flow channels to exchange heat. In the illustrated embodiment, heat exchanger elements 110 and 120 are provided with a first port opening O1, a second port opening O2, a third port opening O3, and a fourth port opening O4. Regions surrounding port openings O1 to O4 are arranged at different heights to achieve selective communication between the port openings and the flow channels. In heat exchanger 100, the regions surrounding port openings O1-O4 are arranged such that the first port opening O1 and the second port opening O2 are fluidly connected to each other through some flow channels, while the third port opening O3 and the fourth port opening O4 are fluidly connected to each other through adjacent flow channels. In the illustrated embodiment, heat exchanger elements 110 and 120 are rectangles with rounded corners, wherein port openings O1-O4 are arranged near the corners. Alternatively, heat exchanger elements 110 and 120 are squares, for example, with rounded corners. Alternatively, the heat exchanger elements 110, 120 may be circular, elliptical, or arranged in other suitable shapes, with the port openings O1-O4 distributed in a suitable manner. In the illustrated embodiment, each heat exchanger element 110, 120 forms four port openings O1-O4. In other embodiments of the invention, the number of port openings may be greater than four, i.e., six, eight, or ten. For example, the number of port openings is at least six, wherein the heat exchanger is configured to provide heat exchange between at least three fluids. Thus, according to one embodiment, the heat exchanger is a three-loop heat exchanger having at least six port openings, and may or may not have at least one integrated suction gas heat exchanger.

[0020] according to Figure 1 The heat exchanger 100 includes a cover plate 130 and an end plate 140. For example, the cover plate 130 and the end plate 140 are conventional designs.

[0021] Reference Figure 2A heat exchanger 100 comprising multiple heat exchanger elements 110, 120 is schematically shown according to one embodiment, without a cover plate 130 and an end plate 140, to illustrate the structure of the heat exchanger elements 110, 120. Each heat exchanger element 110, 120 includes multiple plates that form the heat exchanger element as a double-walled plate type heat exchanger element. In the illustrated embodiment, the first heat exchanger element 110 includes a first plate 150 and a second plate 160, wherein the second heat exchanger element 120 includes a third plate 170 and a fourth plate 180 to form a double-walled structure for each heat exchanger element 110, 120. For example, the first heat exchanger element 110 is formed by the first plate 150 and the second plate 160, wherein the second heat exchanger element 120 is formed by the third plate 170 and the fourth plate 180. Plates 150-180 are formed with ridges R and grooves G to form the ridges R and grooves G of the heat exchanger elements 110, 120. In the same heat exchanger elements 110 and 120, the ridges R and grooves G of plates 150-180 accommodate each other, and the ridges R and grooves G of heat exchanger elements 110 and 120 are arranged to form flow channels between them. Therefore, in the illustrated embodiment, the ridge R of the second plate 160 is accommodated in the ridge R of the first plate 150 to form the first heat exchanger element 110, wherein the ridge R of the fourth plate 180 is accommodated in the ridge R of the third plate 170 to form the second heat exchanger element 120. A double-wall structure is provided for fluid leakage from the flow channels. Flow channels are arranged between heat exchanger elements 110 and 120 and are used for heat exchange between fluids flowing in different flow channels. Flow channels are formed between the second plate 160 and the third plate 170. For example, there are no flow channels between the plates of the same heat exchanger elements 110 and 120, specifically between the first plate 150 and the second plate 160 of the first heat exchanger element 110, and between the third plate 170 and the fourth plate 180 of the second heat exchanger element 120. When the stack of plates 150-180 is brazed to form heat exchanger 100, the plates 150-180 are connected to each other in brazed joints.

[0022] Also refer to Figure 3According to one embodiment, heat exchanger elements 110 and 120 are shown in more detail, wherein plates 150-180 are formed with mating protrusions 190 and recesses 200, thereby forming leakage channels 210 for fluid leakage from flow channels. The protrusions 190 and recesses 200 are distributed to provide a plurality of leakage channels 210 in plates 150-180. The leakage channels 210 are arranged to collect leakage fluid from flow channels, i.e., from opposite sides of the plates. Thus, the leakage channels 210 are arranged to collect fluid leaking through the plates, such as through holes in the plates, or through faulty or broken brazed joints, to opposite sides of the plates, for example, around port openings O1-O4 or at the peripheral skirt S. The leakage channels 210 extend across the ridges R and grooves G of the heat exchanger elements 110 and 120. The leakage channels 210 are distributed on the surfaces of plates 150-180. For example, plates 150-180 are rectangular, with leakage channels 210 distributed across the width of the plate and extending in the longitudinal direction. Therefore, gaps exist between adjacent leakage channels 210. For example, the plates are in contact with each other between the leakage channels 210 to provide efficient heat transfer. For example, the leakage channels 210 are relatively narrow, such that the gaps between them cover a larger plate area than the leakage channels 210 cover. In the illustrated embodiment, the leakage channels 210 extend substantially parallel to each other.

[0023] The leakage passages 210 of each heat exchanger element 110, 120 are connected to each other within the same heat exchanger element 110, 120 via at least one connecting space 220. The connecting space 220 connects the leakage passages 210 to leakage outlets 230. For example, the connecting space 220 connects the leakage passages 210 to several leakage outlets, such as no more than four leakage outlets or no more than two leakage outlets. In the illustrated embodiment, the connecting space 220 connects all the leakage passages of the heat exchanger elements 110, 120 to a single leakage outlet 230. In the case of rectangular plates 150-180, the leakage outlets 230 are arranged, for example, at a single short side of each heat exchanger element 110, 120, as shown. Alternatively, the leakage outlets are arranged in two short sides of the heat exchanger elements 110, 120. In the illustrated embodiment, the connecting space 220 connects the leakage passages 210 to the leakage outlets 230 via two central leakage passages. Therefore, the connecting space 220 is arranged between the first pair of adjacent port openings O1, O3 and the second pair of adjacent port openings O1, O4, for example, close to one of the pairs of adjacent port openings, wherein one or more central leakage channels 210 extend from the connecting space 220 between the port openings of the pairs of adjacent port openings and further extend to the leakage outlet 230, such that leaking fluid can be guided from any of the leakage channels 210 to the leakage outlet 230, for example, a single leakage outlet in the short side. The connecting space 220 is elongated and extends in a direction intersecting with the plurality of leakage channels 210 to connect them, so that leaking fluid can flow between the leakage channels 210.

[0024] In the illustrated embodiment, the leak outlet 230 is formed by a hole in the skirt S of at least one plate of the heat exchanger elements 110, 120, such that fluid collected between the plates of the heat exchanger elements 110, 120 can exit the heat exchanger 100. For example, the skirts S of three consecutive plates, such as the first, second, and third plates 150-170, are formed with aligned leak outlets 230 to provide a common leak outlet from the leak passages 210 of two adjacent heat exchanger elements 110, 120. A fourth plate 180 is formed, for example, with a continuous skirt S or at least a skirt without corresponding holes, to keep any leaking fluid separate from any leaking fluid from adjacent flow passages. Thus, any fluid leaking from a particular flow passage can be collected in a single common leak outlet 230, regardless of the location of the leak.

[0025] Reference Figures 4-6 A leakage path 210 between plates 150-180 within the same heat exchanger elements 110, 120 is shown in more detail according to one embodiment. Figure 5 As shown, the protrusion 190 and the recess 200 cooperate to form a leakage channel 210. Figure 5The diagram has been simplified to better illustrate the leakage path 210. Protrusions 190 on every other plate (e.g., the first plate 150 and the third plate 170) face recesses 200 on other plates (e.g., the second plate 160 and the fourth plate 180) to form leakage paths 210 through the ridge R and the groove G, such that fluid leaking from the flow channel can be conveyed along one or more leakage paths 210 (e.g., the leakage path 210 closest to the leak) to the leakage outlet 230, and, if necessary, through the connecting space 220. For example, the protrusions 190 and recesses 200 are arranged in rows, such as in a substantially straight row in the longitudinal direction of the plates, as shown below. Figure 4 As shown. In Figure 4 In one embodiment, a protrusion 190 can be seen in the groove G of the first plate 150. For example, the protrusion 190 and the recess 200 are arranged to provide at least one or two central leakage channels 210, which extend along the plate between the first and second port openings O1, O3 and between the second and fourth port openings O2, O4. Figure 6 As shown, the plates 150, 160 of the first heat exchanger element 110 and the plates 170, 180 of the second heat exchanger plate 120 are in contact with each other in the region between the protrusion 190 and the recess 200 forming the leakage channel 210, so as to provide effective heat exchange between the fluids in the flow channel. Figure 5 and Figure 6 The reference numeral 240 is used in the accompanying drawing. For illustrative purposes, Figure 6 It has been simplified. However, as Figure 6 As seen, the first and second plates 150, 160 are in contact with each other in the area between the leakage channels 210, and the third and fourth plates 170, 180 are also in contact with each other in the area between the leakage channels 210, and the flow channel 240 is arranged between the second and third plates 160, 170.

[0026] Reference Figures 7-9 The connection space 220 is shown in more detail according to one embodiment. At least one connection space 220 is arranged for connecting the leakage channel 210. For example, 1 to 10 connection spaces 220 are provided, such as no more than 6 or no more than 4. According to one embodiment, two connection spaces are provided. The connection space 220 extends along a ridge R and / or a groove G to connect the leakage channel 210 extending in a direction through the ridge R and the groove G. For example, at least one connection space 220 is provided by one or more ridges R and / or one or more grooves G of a selected plate, the ridges R and / or grooves G being formed at a different height than the corresponding ridges and / or grooves of other plates, such that the connection space 220 extends along the gap formed between them. For example, the connection space 210 is formed in a plurality of adjacent ridges R and / or grooves G, such as 2 to 10 or 2 to 6 or 4 adjacent ridges R and / or grooves G. As simplified Figure 8As shown, the connecting space 220 is provided by two slots G of the first plate 150, which are arranged to have a smaller height than the corresponding slots G of the second plate 160, wherein the second plate 160 forms two ridges R, which have a smaller height than the corresponding ridges of the first plate 150. Figure 8 The diagram shows the first plate 150 and the second plate 160. However, the principle of connecting space 220 is the same for the third plate 170 and the fourth plate 180. Figure 8 In this configuration, the connection space 220 is provided by two ridges R of the second plate 160, which are arranged to have a smaller height than the two corresponding ridges R of the first plate 150. Therefore, the connection space 220 is provided by the gap between the plates along the ridges R and / or grooves G, wherein leaking fluid can be conveyed to the leak channel 210 and further conveyed from the leak channel 210 through the connection space 220 to the leak outlet 230, regardless of where the leak is located. For example, the connection space 220 is formed by one or more ridges R and / or grooves G, the pressed depth of which is less than the corrugation depth of the plate, for example, 60-95% or 80-95% of the corrugation depth. Other ridges R and grooves G of plates 150-180 are in substantially complete contact with each other, for example, in a sliding fit, to facilitate efficient heat transfer. Therefore, only a single connection space 220 or a selected number of connection spaces 220 are provided. For example, the connection space 220 is arranged close to a pair of adjacent port openings O1-O4, but not between any pair of adjacent port openings O1-O4, such that the connection space 220 can connect leakage channels 210 distributed across substantially the entire width of the heat exchange elements 110, 120. For example, the final full-length ridge R and / or groove G are arranged to provide the connection space 220 for connecting the leakage channels 210 and the leakage outlet 230. Alternatively, multiple connection spaces 220 are distributed on the surface of the plate to connect the leakage channels 210 at different locations in the longitudinal direction of the plate. Alternatively, the connection space 220 is formed by protrusions and / or recesses in the plate to connect the leakage channels 210.

[0027] An example of leaky flow is in Figure 7 The leak is indicated by a dashed arrow from the leak point to the leak outlet 230. The leak point is indicated by a dot, in this case, a hole in the second plate 160 through which fluid from the flow channel 240 between the second plate 160 and the third plate 170 enters between the second plate 160 and the first plate 150. The leaking fluid will reach the leak channel 210 formed by the engagement of the protrusion 190 and the recess 200, for example, the nearest leak channel 210. The leaking fluid can then flow freely and rapidly along the leak channel 210 to the connecting space 220, where the leaking fluid can flow from one leak channel 210 to another leak channel 210 leading to the leak outlet 230.

Claims

1. A double-walled plate heat exchanger (100), comprising a plurality of double-walled plate heat exchanger elements (110, 120), wherein, The heat exchanger elements (110, 120) are formed with a pattern of ridges (R) and grooves (G) to provide contact points between at least some intersecting ridges and grooves of adjacent heat exchanger elements (110, 120), and flow channels (240) for fluid heat exchange are formed between adjacent heat exchanger elements (110, 120). These flow channels are selectively fluidly connected to each other through port openings of the heat exchanger elements (110, 120). Each heat exchanger element (110, 120) includes at least two connected plates (150-180), wherein the plates are formed with ridges (R) and grooves (G) to form the pattern of the ridges and grooves of the heat exchanger elements (110, 120), and wherein leakage channels are formed between the plates of each heat exchanger element (110, 120) for fluid leakage from the flow channels. The plates (150-180) are provided with protrusions (190) and recesses (200) for forming a leakage channel (210) that extends across the ridge (R) and groove (G) between the plates of each heat exchanger element (110, 120). At least one connection space (220) is formed between the plates of each heat exchanger element (110, 120), the connection space (220) connecting a leakage passage (210) located within the same heat exchanger element (110, 120), and The at least one connection space (220) is connected to the leakage outlet (230).

2. The double-walled plate heat exchanger (100) according to claim 1, wherein, The at least one connection space (220) extends along the ridge (R) and / or groove (G) of the plate.

3. The double-walled plate heat exchanger (100) according to claim 1 or 2, wherein, The connecting space (220) is formed by at least one ridge (R) and / or at least one groove (G) of a selected plate, wherein the at least one ridge (R) and / or at least one groove (G) of the selected plate is formed at a different height than the corresponding ridges and / or grooves of other plates.

4. The double-walled plate heat exchanger (100) according to claim 3, wherein, The connection space (220) is formed by one or more ridges and / or grooves of one of the plates of each heat exchanger element, the height of which the height of the one or more ridges and / or grooves of one plate is different from the height of the corresponding ridges and / or grooves of the other plate.

5. The double-walled plate heat exchanger (100) according to claim 1, wherein, Each heat exchanger element (110, 120) includes no more than 8 connection spaces (220), no more than 6 connection spaces, or no more than 4 connection spaces.

6. The double-walled plate heat exchanger (100) according to claim 1, wherein, The leakage passage (210) between the plates (150-180) of each heat exchanger element (110, 120) is connected to no more than two leakage outlets or a single leakage outlet (230).

7. The double-walled plate heat exchanger (100) according to claim 1, wherein, The leakage outlet (230) is arranged in the short side of the rectangular heat exchanger element (110, 120).

8. The double-walled plate heat exchanger (100) according to claim 1, wherein, The plates (150-180) and the heat exchanger elements (110, 120) are rectangular and are connected by brazing, wherein the long sides of the plates (150-180) are connected by continuous brazing joints.

9. The double-walled plate heat exchanger (100) according to claim 1, wherein, The plates (150-180) are provided with an outer peripheral skirt (S), and wherein the skirts of three consecutive plates (150-170) form a perforated leakage outlet (230) to provide a common leakage outlet from the leakage passage (210) of two adjacent heat exchanger elements (110, 120).

10. The double-walled plate heat exchanger (100) according to claim 9, wherein, The holes are aligned.

11. The double-walled plate heat exchanger (100) according to claim 10, wherein, The three consecutive plates (150-170) with aligned holes in the skirt (S) are followed by a plate (180) without corresponding holes in the skirt (S), thereby preventing any mixing of fluids leaking from adjacent flow channels (240).

12. The double-walled plate heat exchanger (100) according to claim 1, wherein, The port openings (O1-O4) are arranged at different heights to provide selective fluid communication between the flow channels (240).

13. The double-walled plate heat exchanger (100) according to claim 1, wherein, A leak sensor is positioned around the heat exchanger plate to detect leaks from the leak outlet (230).

14. The double-walled plate heat exchanger (100) according to claim 1, wherein, The leakage channel (210) extends along the longitudinal direction of the plate (150-180), is arranged in parallel, and is distributed across the width of the plate.

15. The double-walled plate heat exchanger (100) according to claim 1, comprising at least a first heat exchanger element (110) and a second heat exchanger element (120), wherein, The first heat exchanger element (110) includes a first plate (150) connected to a second plate (160), wherein the second heat exchanger element (120) includes a third plate (170) connected to a fourth plate (180), wherein the grooves (G) of the first plate (150) and the third plate (170) are provided with protrusions (190) spanning the grooves (G), and the ridges (R) of the second plate (160) and the fourth plate (180) are provided with recesses (200) spanning the ridges (R), wherein the recesses (200) and the protrusions The components (190) are configured to form the leakage channel (210) between the first plate (150) and the second plate (160) and between the third plate (170) and the fourth plate (180) for collecting fluid leaking from the flow channel (240) between the first heat exchanger element (110) and the second heat exchanger element (120), and wherein the connection space (220) is provided between the first plate (150) and the second plate (160) and between the third plate (170) and the fourth plate (180).

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