Plate-fin heat exchanger, method for manufacturing plate-fin heat exchanger and method for using plate-fin heat exchanger

Abstract

The invention relates to a plate-fin heat exchanger (100) having a heat exchanger block (10), in which heat exchanger passages (1) are arranged in the heat exchanger block (10), each having a distribution and collection structure (2) and one or more central structured sheets (3) arranged between the distribution and collection structures (2), 42) are arranged between the heat exchanger passages (1), and the heat exchanger block (10) is covered on the first side (U) and the second side (L) by a covering structure (51, 52). According to the invention, at least one of the separating structures (41, 42) and / or at least one of the covering structures (51, 52) is designed as a leak detection structure (11), the leakage detection structure has a cavity (43) formed in the leakage detection structure (11) in such a way that the cavity (43) is delimited in the direction of the first side (U) by a first material layer (41a) of the leakage detection structure (11) and in the direction of the second side (L) by a second material layer (42a), in a region of the leakage detection structure (11) that is not occupied by the cavity (43), the first material layer (41a) of the leakage detection structure (11) and the second material layer (42a) of the leakage detection structure (11) are separated from the second material layer (42a). The first material layer (41a) and the second material layer (42a) are connected to each other, the width of the cavity (43) in a direction parallel to the first material layer (41a) and the second material layer (42a) is smaller than the width of the central structured sheet (3) of the heat exchanger passage in the direction, and a measuring device (45, 46, 50) is provided for measuring the width of the central structured sheet (3) in the direction. The measuring device is designed to detect a variable relating to a rupture of a wall of the cavity (43) or a rupture of an element arranged in the cavity (43). The invention likewise relates to a method for producing a corresponding plate-fin heat exchanger (100) and to a method for using a plate-fin heat exchanger (100) of this type.

Description

[0001] The invention relates to a plate-fin heat exchanger, a method for producing a corresponding plate-fin heat exchanger and a method for using a corresponding plate-fin heat exchanger. Background Art

[0002] Brazed aluminum plate-fin heat exchangers (PFHE; designation in German and English according to ISO 15547-2:3005) can be used in a large number of process plants at very different pressures and temperatures. For example, they are used for cryogenic air separation, for natural gas liquefaction and in ethylene production plants. Whenever the term "heat exchanger" or "plate heat exchanger" is used hereinafter for short, the corresponding brazed plate-fin heat exchanger is always meant, which can be made in particular of aluminum, but also of other materials. It should be understood that the term "aluminum" can also refer to aluminum alloys.

[0003] The plate heat exchangers mentioned differ significantly in their design from heat exchangers of the printed circuit heat exchanger (PCHE) type. The latter are compact plate heat exchangers, usually having a core made of metal sheets with chemically etched flow channels. After the flow channels have been formed, the metal plates are placed on top of each other in a precise fit and are then joined by diffusion welding to form a solid metal block.

[0004] For example, WO 97 / 03281 A1 proposes to use such a printed circuit heat exchanger to facilitate the operation of a gas turbine. The gas turbine is equipped with a corresponding heat exchanger in which heat is removed from compressed air, which is taken from the compressor section and used to cool the turbine section. The heat exchanger transfers heat from the cooling air to a fluid (such as fuel) to be injected back into the combustion section of the gas turbine without using an intermediate heat transfer fluid. When the fluid is introduced into the combustion chamber of the gas turbine, the heat extracted from the cooling air is returned to the circuit.

[0005] The service life of the corresponding plate-fin heat exchanger depends in particular on the occurrence of strong thermal gradients and mechanical stresses caused thereby. Structural weakening caused by mechanical stresses can accumulate and eventually lead to leaks in the field. In plate-fin heat exchangers, stresses and leaks can occur, especially inside and outside the field of vision, making it impossible to detect them early. Leaks can lead to unplanned shutdowns of the corresponding plants, resulting in production losses and thus significantly increasing the overall costs of remedial measures.

[0006] EP 3 704 431 A1 proposes a plate-fin fluid treatment device with active layers, wherein each active layer comprises plate fins, which are arranged in a sandwich shape between separation sheets so that an active fluid space is defined between the separation sheets. The active layer comprises an outermost active layer having an inlet and an outlet. The outermost active layer is followed by a layer structure with plate fins, which are arranged between the separation sheet and the top cover sheet. The layer structure has a sealed fluid space. A pressure monitoring system is connected to the fluid space of the layer structure. A decompression device is designed to release the pressure in the fluid space when a preset pressure is exceeded.

[0007] The object of the invention is to improve leak detection in a plate-fin heat exchanger of the described type. Summary of the invention

[0008] This object is achieved by a plate-fin heat exchanger, a method for producing a corresponding plate-fin heat exchanger and a method of using a corresponding plate-fin heat exchanger, which have the corresponding features of the independent patent claims. Embodiments are the subject matter of the dependent claims and the following description.

[0009] According to the present invention, a plate-fin heat exchanger with a heat exchanger block is proposed, wherein heat exchanger passages are arranged in the heat exchanger block, each of the heat exchanger passages has a distribution and collection structure, in particular in the form of a corresponding structured sheet, and one or more central structured sheets arranged between the distribution and collection structures, and wherein a separation structure is arranged between the heat exchanger passages, and the heat exchanger block is covered on the upper side or first side and the lower side or second side by a covering structure arranged parallel to the separation structure. On the one hand, the separation structure and the covering structure can be conventional separation sheets or top cover sheets, but any of these separation structures and covering structures can also be an improved separation structure or covering structure provided according to an embodiment of the present invention, which is designed as a leakage detection structure. At least one such leakage detection structure is provided. Therefore, in an embodiment of the present invention, at least one of the separation structures and / or at least one of the covering structures can be designed as a leakage detection structure.

[0010] It is provided that the corresponding leakage detection structure has a cavity formed in the leakage detection structure, such that the cavity is bounded in the direction of the first side of the heat exchanger block by the first material layer of the leakage detection structure and in the direction of the second side of the heat exchanger block by the second material layer. It should be understood that in embodiments of the present invention, several cavities may also be provided, wherein the following explanations apply to each of the cavities.

[0011] In the area of ​​the leakage detection structure not occupied by the cavity, the first material layer and the second material layer can be connected to each other via a solder layer or via one or more intermediate elements or intermediate layers, or they can be merged into one part. However, no intermediate structure sheet is provided, such as the case in EP 3704 431A1, in which an "active layer" is used. In this way, the installation space is significantly reduced, and the manufacturing cost and workload are reduced. If the first material layer and the second material layer are not formed integrally, they can be directly adjacent to each other so that they can be separated from each other only by a solder layer. Alternatively, an intermediate layer can also be provided, which can have a groove defining the cavity in the area of ​​the cavity.

[0012] The width of the cavity in a direction parallel to the first material layer and the second material layer is smaller than the width of the central structured sheet of the heat exchanger passage in the same direction, in particular the total width. "Width" especially means the smallest extension in the corresponding direction. In particular the dimension perpendicular to the longitudinal extension. In particular less than 1 / 50, 1 / 10 or 1 / 5 of the width of the structured sheet, and for example more than 1 / 100. In the case of, for example, a meandering, sinusoidal or other periodic configuration, the amplitude in the mentioned direction may also be correspondingly smaller than the width of the structured sheet.

[0013] Furthermore, it is intended to provide a measuring device which is designed to detect a variable associated with a rupture of a wall of the cavity or of an element arranged in the cavity. A corresponding rupture in the wall may in particular result in a flow of fluid into the cavity and / or a flow of fluid out of the cavity, so that in this case a pressure loss or a pressure increase in particular characterizes the corresponding rupture and can be detected in a corresponding embodiment of the invention. In other embodiments of the invention, a structure may be introduced into the cavity, such as an optical waveguide or a (in particular insulated) cable, the break of which may be detected by detecting an interruption of a light or current signal.

[0014] As understood herein, the term "upper side" refers to the outward surface of a heat exchanger block formed by one of its top cover sheets, and the "lower side" refers to the outward surface of a heat exchanger block formed by the other top cover sheet. The upper side and the lower side can be parallel to each other and can also be parallel to the separating sheet or its (largest) surface and the top cover sheet or its (largest) surface. Depending on the type of manufacture, such parallelism is not a mandatory requirement. The terms "in the direction of the upper side" and "in the direction of the lower side" refer to directions perpendicular to planes parallel to the alignment of the separating sheet and the top cover sheet, or directions in which the separating sheet and the top cover sheet are located. The direction indicated relative to the width of the cavity extends in particular perpendicularly to the direction on the upper side and the direction on the lower side.

[0015] The orientation of the corresponding direction is indicated by specifying the target ("in the direction of the upper side" or "in the direction of the lower side"). Alternatively, the two directions may also be defined as being each perpendicular to the plane spanned by each relevant separation sheet (or its surface) and oriented in opposite directions to each other.

[0016] The terms "first side" and "second side" may also be used to replace the terms "upper side" and "lower side", so that the description "in the direction of the upper side" may also be replaced by "in the direction of the first side" or "in the first direction". The same applies to the term "in the direction of the upper side", which may be replaced by "in the direction of the second side" or "in the second direction". The upper side and the lower side may also be arranged as front, back, left, right, etc. during operation of the corresponding heat exchanger block, and should not be understood as limiting.

[0017] In one embodiment of the invention, the first material layer can be formed by a first sheet material and the second material layer can be formed by a second sheet material, wherein in this case, the cavity can be provided by a groove in the surface of the first sheet material facing in the direction of the second side and / or by a groove in the surface of the second sheet material facing in the direction of the first side. If corresponding grooves are provided in both sheets, they in particular form a cavity together and are accordingly aligned above each other. In other embodiments, as described above, the first material layer and the second material layer can also be connected to each other via an intermediate layer, in particular an intermediate sheet material, wherein the groove formed in the intermediate layer can define the cavity.

[0018] The first sheet and the second sheet may be (brazed) welded or otherwise connected to each other in the area of ​​the leak detection structure not occupied by the cavity. The same applies to any intermediate layers that may be present. In particular, the mentioned grooves may be formed by embossing or material removal (e.g. laser ablation, milling, corrosion, etc.).

[0019] Therefore, in this embodiment, the corresponding sheet structure comprises (in particular between at least two of the heat exchanger paths in the heat exchanger path) two sheets, between which no structural sheet is arranged, and which together form a separation sheet (in the form of a double sheet), and / or the corresponding sheet structure on the upper side and / or lower side of the heat exchanger block comprises in particular two sheets, between which no structural sheet is arranged, and which together form a top cover sheet (in the form of a double sheet).

[0020] Therefore, in such embodiments of the invention, in particular, a double separating sheet or a top cover sheet is used as a leak detection structure so as to be inserted into a hollow volume or a control volume, for example under the side bars in a dedicated manner (as explained in detail below). For example, the volume is pressure monitored so that a tear in one of the separating sheets or the top cover sheet (especially in the area of ​​the side bars) and the infiltration or outflow of fluid can be detected via a pressure change in the control volume. The size of the volume and therefore, for example, the weakening of the side bars is selected so that a double separating sheet or a top cover sheet with a control volume under the side bars has a mechanical stability similar to or slightly lower than a single separating sheet or a top cover sheet.

[0021] In other embodiments of the present invention, the first material layer and the second material layer may also be part of an integrally formed metal structure in which the cavity is formed or cut. For example, a single separate sheet or cover sheet or a modified metal structure may also be used, wherein the cavity is introduced into the separate sheet by a suitable manufacturing method, or the cavity is manufactured by a suitable manufacturing method (e.g., casting, any kind of additive manufacturing method). A combination of dual sheets and single sheets may also be used.

[0022] The invention enables early and reliable detection of leaks and other damages such as cracks.For example, the solution proposed according to the invention can be realized in a technically simpler way and with less space requirement than the prior art explained at the outset.

[0023] In the embodiments of the present invention already mentioned, the variable related to the rupture of the wall of the cavity or the rupture of the element arranged in the cavity can be a variable characterizing the flow of fluid into the cavity and / or the flow of fluid out of the cavity. With regard to the corresponding embodiment, the variable will be referred to as the pressure in the cavity below, and the pressure increases when the fluid flows into the cavity, and the pressure decreases when the fluid flows out of the cavity. However, in such embodiments, the measurement method based on optical, magnetic, electromagnetic or acoustic effects can also be used to monitor the cavity. The monitored physical effect may need to introduce suitable transmission materials (e.g., glass fibers). Only for simplicity, a pressure value will be referred to below.

[0024] In one embodiment of the invention, the measuring device has a computing unit or is connected or connectable to a computing unit, wherein the computing unit is designed to monitor a variable, such as a pressure in a cavity, an electrical signal, an optical signal, etc., and is also designed to detect a leak in the heat exchanger block or a rupture in one of the mentioned structures based on the monitored variable. The corresponding leak detection can be based on a threshold comparison, for example, and can include any signal processing methods, such as determining a moving average, in order to eliminate short-term fluctuations of the variable. Alternatively or additionally, data-driven models and machine learning methods can also be used in this case.

[0025] In an embodiment of the invention, if a corresponding double sheet (with a first sheet and a second sheet) is used, the cavity can be formed by a groove in one of these sheets, or by a groove in both sheets facing each other, as described above. For example, in the first alternative, only one of the sheets needs to be weakened or extensively processed, while in the second alternative, a larger cavity can be created. If the groove is present in the middle plate, the upper and lower sheets remain unworn.

[0026] In an embodiment of the present invention, the cavity in the leakage detection structure may extend alternately on both sides of the center line. Specifically, it may be a channel that bends or extends in a zigzag shape. The center line may be located in particular parallel between the upper side and the lower side of the corresponding leakage detection structure. However, as mentioned above, parallelism is not necessary. In an embodiment with two sheets, a groove or a groove in a groove facing each other in the two sheets may extend alternately on both sides of the corresponding center line at least in one section. As described below with reference to Figure 3 As explained in more detail, crack propagation can be limited in this way. In this case, an embodiment in which the center line extends parallel to the side edge of the respective separating sheet and / or the top cover sheet can be advantageous. However, this is not mandatory. However, it can also be provided that the center line extends parallel to or in another suitable orientation to the predicted crack propagation line or the expected crack formation area. For example, the expected crack formation area can be determined by simulation.

[0027] In an embodiment of the present invention, the grooves or corresponding cavities extending alternately on both sides of the center line in at least one section can extend in a zigzag, sinusoidal, wavy or zigzag manner, especially in a plane parallel to the upper and lower sides of the leakage detection structure, and therefore parallel to the first and second sides of the heat exchanger block or the separation sheet and the top cover sheet. However, in this case, other suitable orientations are possible at any time. The choice made in each case can be based in particular on the simplification of the manufacturing technology or the mechanical strength. In particular, the width of the corresponding amplitude parallel to the first material layer and the second material layer is also smaller than the width of the structural sheet in this direction.

[0028] In one embodiment of the invention, side bars may be arranged on both sides of the central structured sheet in the heat exchanger passage. In a vertical projection on a plane arranged in particular (but not necessarily) parallel to the first and second sides of the heat exchanger block or the separation structure and the covering structure or their surfaces, the projection surface of the separation structure and the covering structure is particularly substantially completely overlapped. The corresponding projection surface of the side bar overlaps with the peripheral area of ​​the separation structure and the covering structure or their projection surface, which is common in this aspect of plate-fin heat exchangers. In the corresponding vertical projection, the transition area between at least one of the side bars and at least one of the structured sheets can overlap with the cavity in at least one section. The transition area can be, in particular, a substantially straight line at which the side bar abuts the corresponding structure sheet of the heat exchanger passage. Such a line can therefore intersect with the projection surface of the cavity in the corresponding vertical projection. This arrangement can in particular ensure that the area in the transition area between the side bar and the structure sheet that is particularly prone to leakage or the area of ​​the separation sheet and the top cover sheet covered by it can be provided with a leakage detection option provided according to the present invention. However, alternative embodiments are also possible in which, in the mentioned vertical projection, either only the projection surface of at least one of the sidebars or only at least one of the structured sheets overlaps the projection surface of the cavity.

[0029] In one embodiment of the invention, the cavity can be connected to a drainage device in order to ensure that the liquid flows out in the event of any leakage and, for example, in this way prevent overpressure. A corresponding drainage device can also be designed, for example, for an opening above a predetermined pressure threshold.

[0030] In the plate-fin heat exchanger according to an embodiment of the present invention, a temperature detection component or any other measurement component for detecting temperature or any other measurement value may be provided to be incorporated into the heat exchanger block.

[0031] Furthermore, in a plate-fin heat exchanger of the type explained, in an embodiment of the invention which has also been mentioned, a structure for crack detection, such as an insulated cable or an optical fiber, can be arranged in the cavity or at any other location, which structure is fastened in such a way that it is interrupted when a crack occurs. The resistance value or the current flowing through the cable can be monitored, so that if there is a corresponding interruption, this can (additionally) indicate the presence of a crack. This means that a variable associated with a rupture of an element arranged in the cavity is detected, wherein, as described above, the rupture can be detected by detecting an interruption of the light or current signal.

[0032] In an embodiment of the present invention, in addition to the cavity formed in the explained manner, another cavity of the same or different design may also be arranged in the leakage detection structure, wherein the cavities may be arranged in the leakage detection structure without being connected to each other. The sections of the two cavities may be arranged alternately with each other, or may intersect the axis alternately.

[0033] A method for manufacturing a plate-fin heat exchanger having a heat exchanger block is also the subject of the present invention. The method comprises forming a stacked assembly comprising a plurality of heat exchanger passages, wherein the heat exchanger passages are each formed by arranging a plurality of distribution and collection structures and a central structured sheet, wherein separation structures are each arranged between the heat exchanger passages, and wherein cover structures are each arranged on a first side and a second side of the stacked assembly. The method also comprises connecting the stacked assembly to form a heat exchanger block.

[0034] According to the present invention, at least one of the separation structures and / or at least one of the covering structures is provided as a leakage detection structure having a cavity, the cavity being arranged in the leakage detection structure in the following manner: the cavity is bounded in the direction of the first side by the first material layer of the leakage detection structure and in the direction of the second side by the second material layer, wherein in the area of ​​the leakage detection structure not occupied by the cavity, the first material layer and the second material layer are connected to each other. The width of the cavity in a direction parallel to the first material layer and the second material layer is smaller than the width of the central structured sheet of the heat exchanger passage in the same direction, i.e. the width of one or more structured sheets in one or more heat exchanger passages. In addition, it is intended to provide a measuring device designed to detect variables associated with the rupture of the cavity or the rupture of an element arranged in the cavity. The method may in particular include providing the features explained in detail previously according to different embodiments of the present invention.

[0035] A method for controlling the temperature of at least one fluid is also a subject of the invention, in which method a plate-fin heat exchanger is used as explained previously in the embodiments.

[0036] With regard to the features and advantages of the above-described method and embodiments thereof, reference is expressly made to the above explanations of the plate-fin heat exchanger according to the invention and embodiments thereof, since they apply likewise to the respective method implemented and to the corresponding products.

[0037] The invention will now be described in more detail with reference to the accompanying drawings, which illustrate embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A plate-fin heat exchanger is exemplified.

[0039] Figure 2 Various aspects of embodiments of the present invention are illustrated.

[0040] Figure 3 Various aspects of embodiments of the present invention are illustrated.

[0041] Figure 4 Various aspects of embodiments of the present invention are illustrated.

[0042] Figure 5 Various aspects of embodiments of the present invention are illustrated.

[0043] Figure 6 Various aspects of embodiments of the present invention are illustrated.

[0044] Figure 7 Various aspects of embodiments of the present invention are illustrated. DETAILED DESCRIPTION

[0045] In the drawings, the same reference numerals are used for elements that correspond to each other in terms of structure and / or function. These elements are not explained again. If device features are explained below, the corresponding explanation also applies to the method steps, and vice versa.

[0046] In the above ISO 15547-2:3005 Figure 2 A brazed plate-fin heat exchanger made of aluminum is shown and described in and on page 5 of the ALPEMA publication "The Standards of the Brazed Aluminium Plate-Fin Heat Exchanger Manufacturers' Association", 3rd edition, 2010. Figure 1 A diagram substantially corresponding to the diagram therein is shown in FIG. 1 and will be explained below. Figure 1 The plate heat exchanger 100 with a central portion open is used for heat exchange of five different process media A to E in the example shown.

[0047] In order to carry out heat exchange between process media A to E, the plate heat exchanger 100 comprises a plurality of separator sheets 4 arranged parallel to one another (in the aforementioned publication, to which subsequent references in brackets also refer, these are referred to as "separator sheets" and in this case also as separator structures), between which heat exchange paths 1 (in each case for one of the process media A to E) are formed which are defined by structured sheets with fins 3 and by which heat exchange can be carried out with one another.

[0048] As ISO 15547-2:3005 Figure 1 As shown, the structured sheet 3 is generally folded or corrugated, and the flow channels are formed by each of the folds or corrugations. Providing a structured sheet 3 provides the advantages of improved heat transfer, more targeted fluid guidance, and increased mechanical (tensile) strength. In the heat exchange passage 1, the process media A to E flow, specifically separately through the separation sheet 4, but, in the case of a perforated structured sheet 3, can optionally pass through the latter.

[0049] The individual passages 1 are surrounded on each side by so-called side bars 8, which however leave space for the supply and removal openings 9. The side bars 8 hold the separating sheet 4 at a certain distance and ensure mechanical reinforcement of the pressure chamber. A particularly reinforced cover sheet 5 ("top cover sheet") is arranged parallel to the separating sheet 4 and serves in particular to close at least two sides.

[0050] By means of so-called headers 7 provided with nozzles 6, the process media A to E are supplied and discharged via supply and removal openings 9. In the inlet region of the passage 1, there is also a structured sheet 2 with so-called distributor fins, which ensures a uniform distribution over the entire width of the passage 1. Further structured sheets 2 with collecting fins, seen in the flow direction, can be located at the ends of the passage 1 and guide the process media A to E from the passage 1 into the headers 7, where they are collected and discharged via corresponding nozzles 6. In this text, they are also referred to as "distribution and collection structures".

[0051] The heat exchanger block 10, which is a cube in this case, is generally formed by the structured sheets 2 and 3, the side bars 8, the separator sheet 4 and the top cover sheet 5, wherein the "heat exchanger block" is understood herein to mean the said element in the interconnected state without the header 7 and the nozzle 6. As used herein, the "upper side" or first side refers to the outward surface of the heat exchanger block 10 formed by one top cover sheet 5, and the "lower side" or second side refers to the outward surface of the heat exchanger block 10 formed by the other top cover sheet 5. Figure 1 In the example, the upper or first side is marked as U and the lower or second side is hidden and indicated by L. Figure 1 Not illustrated in the drawings, the plate heat exchanger 100 may be formed from several cuboidal and interconnected heat exchanger blocks 10 , in particular for manufacturing reasons.

[0052] The plate heat exchanger 100 is made, for example, of aluminum brazing. In this case, the passages 1 comprising the structured sheets 2 and 3, the separator sheets 4, the top cover sheets 5 and the side bars 8 are each provided with solder, stacked one on top of the other or arranged accordingly, and heated in a furnace. The headers 7 and the nozzles 6 are welded to the heat exchanger block 10 manufactured in this way.

[0053] Figure 2 A structure according to one embodiment of the present invention is illustrated and generally designated 20. The structure 20 represents Figure 1 , wherein the corresponding elements are not true to scale but are illustrated in cross section between the upper side or first side U and the lower side or second side L. The representation of the side bars 8 is omitted here. The arrangement continues downwards in essentially the same manner, as shown in FIG. Figure 2. Any other continuation is also possible. So-called dummy layers (channels through which no flow occurs) may also be provided. Dummy layers may also be present at the outer ends of active channels and adjoin on the top cover sheet.

[0054] As shown in arrangement 20, the heat exchanger path previously designated as 1 is arranged in the heat exchanger block previously designated as 10. Figure 2 As shown in Figure 2 As shown, two separation sheets 41, 42 are arranged between the heat exchanger passage 1 or the structural sheet 3, which, as shown with reference to the following figures, form a leakage detection structure 11. In addition, in the embodiment illustrated herein, the upper side or first side U of the heat exchanger block 10 is covered by two top cover sheets 51, 52. As shown with reference to the following figures, they also form a leakage detection structure, which is also marked as 11 for simplicity. The lower side or second side L can be designed accordingly. In other words, double separation sheets 41, 42 or top cover sheets 51, 52 are arranged here, each of which forms a leakage detection structure 11.

[0055] In the following, reference Figures 2 to 5 , the features of the embodiments of the present invention are illustrated using the separator sheets 41, 42. The top cover sheets 51, 52 can each be designed in the same or similar manner and will not be explained in detail only for the sake of clarity.

[0056] In the present description Figure 4 , a corresponding structure 20 is again illustrated, wherein in this case, in addition to the structured sheet 3, side bars 8 are also shown.

[0057] from Figure 4 Or as can be seen in the arrangement shown herein, two separation sheets 41 , 42 are arranged between at least two heat exchanger passages 1 without a structural sheet 3 arranged therebetween, which forms a leak detection structure 11 , and a cavity 43 is arranged between the two separation sheets 41 , 42 .

[0058] Furthermore, a measuring device is provided which, in the example illustrated here, has a sensor 45, a measuring cable 46 and a computing unit 50. The latter is designed to detect the pressure in the cavity 43, evaluate it in the manner explained, and thus detect a leak.

[0059] from Figure 4As can be seen in FIG, the cavity 43 is delimited in the direction of the upper or first side U by the upper side or first material layer 41a of the leakage detection structure 11, and in the direction of the lower or second side L by the lower side or second material layer 42a, wherein the upper side or first material layer 41a is formed by the upper side or first sheet 41, and the lower side or second material layer 42a is formed by the lower side or second sheet 42. In this case, the cavity 43 is formed by a groove in the surface of the upper side or first sheet 41 facing in the direction of the lower side or second side L and by a groove in the surface of the lower side or second sheet 42 facing in the direction of the upper side U or first side, which are placed one on top of the other in a precisely fitting manner.

[0060] The width of the cavity 43 in a direction parallel to the first material layer 41a and the second material layer 42b (ie, the width in a horizontal direction in the plane of the drawing) is smaller than the width of the structured sheet 3 in the same direction.

[0061] from Figure 4 As can also be seen in the figure, and as indicated by the dot-dash lines which do not themselves represent structural elements, in a vertical projection onto a plane parallel to the upper side U and the lower side L, the transition zone between at least one of the side bars 8 and at least one of the structured sheets 3 (marked by the dot-dash lines) overlaps the cavity 43 or its projection surface in at least one section. Alternative embodiments are possible in which, in the mentioned vertical projection, either only at least one of the side bars 8 or only at least one of the structured sheets 3 overlaps the cavity 44 or its projection surface. These are not based on Figure 4 Implementation alternatives are illustrated in the form of dashed ovals.

[0062] Figure 5 , where the corresponding projections on a plane corresponding to the paper plane are illustrated. A portion of the projection surface of the side bar is illustrated here as 8', a portion of the projection surface of the first sheet or the second sheet is illustrated as 41', and a portion of the projection surface of the cavity is illustrated as 43', in which case the projection surface of the cavity is assumed to be straight. In this case, the width of the cavity 43 in a direction parallel to the first material layer 41a and the second material layer 42b is in particular also horizontal in the plane of the drawing.

[0063] In what will now be described Figure 3 In the figure, the corresponding upper sheet 41 or lower sheet 42 is illustrated in a partial perspective view, wherein an axis shown by a dashed line in this case extends parallel to the paper surface, which axis indicates the direction in which the interpreted width of the cavity lies.

[0064] If already in Figure 4As shown, the cavity 43 can be formed by a groove in one of the sheets 41, 42 or 51, 52, or by a groove in the corresponding sheets 41, 43 or 51, 52 facing each other. Figure 3 44 in the figure. Of course, several grooves 44 can also be provided, which can be formed in the sheets 41, 42 or 51, 52. The grooves 44 can be provided, for example, by milling, stamping or applying material at other locations. As mentioned above, a metal structure is provided within the scope of the present invention, but a single metal structure with a cavity 43 can also be provided, wherein the cavity can be cut out or formed in the metal structure, for example, by casting, additive manufacturing or other methods. In the following, without any intentional limitation, reference is made to two separate sheets 41, 42. However, the corresponding explanations also apply to cavities formed or provided in the metal structure.

[0065] As described above, one groove 44 or at least one of the grooves 44 facing each other in the two separating sheets 41, 42 may extend alternately on both sides of the center line M at least in one section and be located in a plane parallel to the upper and lower sides of the corresponding sheet. Figure 6 The middle section 44a is exemplified in which the grooves extend in a curved manner, whereas on the opposite side of the separation sheets 41, 42, the grooves extend in a straight line.

[0066] exist Figure 7 In the embodiment shown, at least sections 44b, 44c are formed which interlock with each other without intermediate connections, thereby providing two independent monitoring circuits. For example, they may be straight or meandering.

[0067] As mentioned several times, but not illustrated separately here for the sake of clarity, elements or structures, in particular in the form of insulated cables or optical fibers, can also be introduced into the cavity 43 , the rupture of which can be detected by evaluating an optical or current signal.

Claims

1. A plate-fin heat exchanger (100) having a heat exchanger block (10), wherein heat exchanger passages (1) are arranged in the heat exchanger block (10), the heat exchanger passages each having a distribution and collection structure (2) and one or more central structured sheets (3) arranged between the distribution and collection structures (2), wherein separation structures (41, 42) are arranged between the heat exchanger passages (1), and the heat exchanger block (10) is covered on a first side (U) and a second side (L) by a covering structure (51, 52), characterized in that At least one of the separation structures (41, 42) and / or at least one of the covering structures (51, 52) is designed as a leakage detection structure (11), and the leakage detection structure has a cavity (43) formed in the leakage detection structure (11) in the following manner: the cavity is bounded in the direction of the first side (U) by a first material layer (41a) of the leakage detection structure (11) and in the direction of the second side (L) by a second material layer (42a), wherein the cavity is bounded in the direction of the second side (L) by a second material layer (42a) of the leakage detection structure (11). In the area occupied by the cavity (43), the first material layer (41a) and the second material layer (42a) are connected to each other, the width of the cavity (43) in a direction parallel to the first material layer (41a) and the second material layer (42a) is smaller than the width of the central structured sheet (3) of the heat exchanger passage in the direction, and a measuring device (45, 46, 50) is provided, which is designed to detect variables related to the rupture of the wall of the cavity (43) or the rupture of the element arranged in the cavity (43).

2. The plate-fin heat exchanger (100) according to claim 1, wherein the variable associated with the rupture of the wall of the cavity (43) or the rupture of the element arranged in the cavity (43) is a variable characterizing the flow of fluid into the cavity (43) and / or the flow of fluid out of the cavity (43).

3. A plate-fin heat exchanger (100) according to claim 1 or 2, wherein the first material layer (41a) is formed by a first sheet (41), and the second material layer (42a) is formed by a second sheet (42), wherein the cavity (43) is provided by a groove (44) in a surface of the first sheet (41) facing the direction of the second side (L) and / or by a groove (44) in a surface of the second sheet (42) facing the direction of the first side (U).

4. The plate-fin heat exchanger (100) according to claim 3, wherein the groove (44) is formed by embossing or material removal.

5. The plate-fin heat exchanger (100) according to claim 1 or 2, wherein the first material layer and the second material layer are parts of an integrally formed metal structure, and the cavity (43) is formed or arranged in the integrally formed metal structure.

6. The plate-fin heat exchanger (100) of claim 5, wherein the metal structure is formed using an additive manufacturing method.

7. A plate-fin heat exchanger (100) according to any one of the preceding claims, wherein the variable associated with a rupture of a wall of the cavity (43) or a rupture of an element arranged in the cavity (43) is the pressure in the cavity.

8. A plate-fin heat exchanger (100) according to any one of the preceding claims, wherein the measuring device (45, 46, 50) has a computing unit (50) or is connected or can be connected to a computing unit (50), wherein the computing unit (50) is designed to monitor the variables associated with a rupture of a wall of the cavity (43) or a rupture of an element arranged in the cavity (43), and the computing unit is also designed to detect a leak in the heat exchanger block (10) based on the monitored variables.

9. The plate-fin heat exchanger (100) according to any one of the preceding claims, wherein the cavities in the leakage detection structure (11) extend alternately on both sides of a center line.

10. The plate fin heat exchanger (100) according to claim 9, wherein the center line extends to the side edges of the leakage detection structure in a predetermined arrangement.

11. A plate-fin heat exchanger (100) according to claim 9 or 10, wherein the center line extends to a predicted crack propagation line and / or an expected crack formation area in a predetermined orientation, and / or wherein the cavity (44) extending alternately on both sides of the center line in at least one section extends in a zigzag, sinusoidal, wavy or zigzag manner.

12. The plate-fin heat exchanger (100) according to any one of the preceding claims, wherein side bars (8) are arranged on both sides of the central structured sheet (3) in the heat exchanger passage (1), wherein: In a vertical projection onto a plane parallel to the first side (U) and the second side (L), a transition region between at least one of the side bars (8) and at least one of the structured sheets (3) overlaps with the cavity (43) in at least one section.

13. A plate-fin heat exchanger (100) according to any one of the preceding claims, wherein the cavity (44) is connected to a drainage device and / or wherein a temperature detection component for detecting temperature is incorporated in the heat exchanger block (10), and / or wherein a cable for crack detection is arranged in the cavity.

14. A method for manufacturing a plate-fin heat exchanger (100), the method comprising the following steps: a) forming a stacking assembly comprising a plurality of heat exchanger passages, wherein the heat exchanger passages are each formed by arranging a plurality of distribution and collection structures (2) and a central structured sheet (3), wherein separation structures (41, 42) are each arranged between the heat exchanger passages, and wherein covering structures (51, 52) are each arranged on a first side (U) and a second side (L) of the stacking assembly, and b) connecting the stacked components to form a heat exchanger block (10), It is characterized by the following steps: c) providing at least one of the separation structures (41, 42) and / or at least one of the covering structures (51, 52) as a leakage detection structure (11) having a cavity (43), the cavity being arranged in the leakage detection structure (11) in the following manner: the cavity (43) is bounded in the direction of the first side (U) by a first material layer (41a) of the leakage detection structure (11) and in the direction of the second side (L) by a second material layer (42a), wherein in an area of ​​the leakage detection structure (11) not occupied by the cavity (43), the first material layer (41a) and the second material layer (42a) are connected to each other, and the width of the cavity (43) in a direction parallel to the first material layer (41a) and the second material layer (42a) is smaller than the width of the central structured sheet (3) of the heat exchanger passage in the same direction, and d) providing a measuring device (45, 46, 50) designed to detect a variable associated with a rupture of a wall of the cavity (43) or a rupture of an element arranged in the cavity (43), said variable being characteristic of an inflow of fluid into the cavity (43) and / or an outflow of fluid from the cavity (43).

15. A method for controlling the temperature of at least one fluid, in which method a plate-fin heat exchanger (100) according to any one of claims 1 to 13 is used.

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