Plate-fin heat exchanger, method for producing a plate-fin heat exchanger and method using a plate-fin heat exchanger

Abstract

A plate-fin heat exchanger (100) which has a heat exchanger block (10) is proposed, wherein heat exchanger passages (1) which each have distribution and collecting structures (2) and one or more central structured sheets (3), which are arranged between the distribution and collecting structures (2), are arranged in the heat exchanger block (10), wherein separating 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 on a second side (L) by covering structures (51, 52). It is provided here that at least one of the separating structures (41, 42) and / or at least one of the covering structures (51, 52) are / is designed as a leak detection structure (11) which has a cavity (43) formed in the leak detection structure (11) in such a manner that the cavity (43) is delimited in the direction of the first side (U) by a first material layer (41a) and in the direction of the second side (L) by a second material layer (42a) of the leak detection structure (11), wherein, in a region of the leak detection structure (11) not taken up by the cavity (43), the first material layer (41a) and the second material layer (42a) are connected to each other, that a width of the cavity (43) in a direction parallel to the first material layer (41a) and the second material layer (42a) is smaller than a width of the central structured sheet or sheets (3) of the heat exchanger passages in this direction, and that a measuring device (45, 46, 50) is provided which is designed to detect a variable correlating to a rupture of the wall of the cavity (43) or 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 in which a plate-fin heat exchanger (100) of this type is used.

Description

[0001] Description

[0002] Plate-fin heat exchanger, method for producing a plate-fin heat exchanger and method using a plate-fin heat exchanger

[0003] The invention relates to a plate-fin heat exchanger, a method for producing a corresponding plate-fin heat exchanger and a method in which a corresponding plate-fin heat exchanger is used.

[0004] Background of the invention

[0005] Brazed aluminum plate-fin heat exchangers (PFHE; designations according to the German and English versions of ISO 15547-2:3005) can be used in a wide variety of process plants at a wide range of pressures and temperatures. Such heat exchangers are used, for example, in the cryogenic separation of air, in the liquefaction of natural gas, or in plants for the production of ethylene. References to "heat exchangers" or "plate heat exchangers" below always refer to brazed plate-fin heat exchangers, which can be made primarily of aluminum, but also of other materials. It is understood that the term "aluminum" can also refer to an aluminum alloy.

[0006] The plate heat exchangers mentioned differ significantly in their design from printed circuit heat exchangers (PCHEs). Printed circuit heat exchangers are compact plate heat exchangers that typically have a core made of metal plates with chemically etched flow channels. After the flow channels are formed, the metal plates are precisely stacked on top of each other and then bonded together by diffusion welding to form a solid metal block.

[0007] The use of such a printed circuit heat exchanger is proposed as advantageous, for example, in WO 97 / 03281 A1 for operation with a gas turbine. The gas turbine is equipped with a corresponding heat exchanger in which heat is removed from compressed air taken from the compressor section and used to cool the turbine section. The heat exchanger transfers the heat from the cooling air to a fluid to be injected back into the combustion section of the gas turbine, such as fuel, without the use of an intermediate heat transfer fluid. The heat extracted from the cooling air is returned to the circuit when the fluid is introduced into the combustion chamber of the gas turbine.

[0008] The service life of corresponding plate-fin heat exchangers depends particularly on the occurrence of strong thermal gradients and the resulting mechanical stresses. Structural weakening resulting from mechanical stresses can accumulate and ultimately lead to leaks in the field. In plate-fin heat exchangers, stresses and leaks can occur particularly inside and out of sight, so they may not be detected early enough. Leaks lead to an unplanned shutdown of the corresponding plant with production downtime, which massively increases the overall cost of remedial measures.

[0009] EP 3 704431 A1 proposes a fin-and-plate fluid processing device with active layers, wherein each active layer comprises a fin plate sandwiched between baffles, defining an active fluid space between the baffles. The active layers comprise an outermost active layer having an inlet and an outlet. Following the outermost active layer, a layered assembly is provided with a fin plate sandwiched between a baffle and a cover plate. The layered assembly has a sealed fluid space. A pressure monitoring system communicates with the fluid space of the layered assembly. A pressure relief device is configured to relieve pressure within the fluid space when a preset pressure is exceeded.

[0010] The present invention aims to improve the detection of leaks in a plate-fin heat exchanger of the type described.

[0011] Disclosure of the Invention This object is achieved by a plate-fin heat exchanger, a method for producing a corresponding plate-fin heat exchanger, and a method in which a corresponding plate-fin heat exchanger is used, having the respective features of the independent patent claims. Further embodiments are the subject of the dependent claims and the following description.

[0012] According to the invention, a fin-plate heat exchanger is proposed which has a heat exchanger block, wherein heat exchanger passages are arranged in the heat exchanger block, each of which has distributor and collector structures, in particular in the form of corresponding structured sheets, as well as one or more central structured sheets arranged between the distributor and collector structures, and wherein separating structures are arranged between the heat exchanger passages and the heat exchanger block is covered on an upper side or first side and a lower side or second side by cover structures arranged parallel to the separating structures.The separating and covering structures can, on the one hand, be conventional separating or covering plates, but any of these separating and covering structures can also be a modified separating or covering structure provided according to an embodiment of the invention, which is designed as a leak detection structure. At least one such leak detection structure is provided. Thus, in embodiments of the invention, at least one of the separating structures and / or at least one of the covering structures can be designed as a leak detection structure.

[0013] It is provided that a corresponding leak detection structure has a cavity formed in the leak detection structure such that the cavity is delimited by a first material layer toward the first side of the heat exchanger block and by a second material layer of the leak detection structure toward the second side of the heat exchanger block. It is understood that in embodiments of the invention, multiple cavities may also be provided, with the following explanations applying to each of the cavities.

[0014] In an area of ​​the leak detection structure not occupied by the cavity, the first material layer and the second material layer can be connected to one another via a solder layer or via one or more intermediate elements or intermediate layers, or these can merge into one another in one piece. However, no intermediate structural sheets are provided, as is the case, for example, in EP 3 704431 A1 with an "active layer" used there. In this way, the installation space is significantly reduced and manufacturing costs and effort are reduced. The first material layer and the second material layer, if they are not formed in one piece, can abut one another directly, so that they can only be separated from one another by a solder layer. Alternatively, an intermediate layer can also be provided, which can have a recess defining the cavity in the region of the cavity.

[0015] A width of the cavity in a direction parallel to the first and second material layer is less than a width, in particular a total width, of the central structured sheet(s) of the heat exchanger passages in the same direction. The “width” here represents in particular the smallest extension in a corresponding direction. It is in particular the dimension perpendicular to a longitudinal extension. It is in particular less than 1 / 50, 1 / 10 or 1 / 5 and for example more than 1 / 100 of the width of the structured sheet(s). In the case of, for example, a meandering, sinusoidal or otherwise periodic configuration, an amplitude in the said direction can also be correspondingly less than the width of the structured sheet(s).

[0016] Furthermore, it is provided that a measuring device is provided which is designed to detect a variable which correlates with a rupture of a wall of the cavity or of an element arranged in the cavity. A corresponding rupture in a wall can in particular cause fluid to flow into the cavity and / or fluid to flow out of the cavity, so that in this case in particular a pressure loss or an increase in pressure characterizes a corresponding rupture and can be detected in corresponding embodiments of the invention. In other embodiments of the invention, a structure can also be introduced into the cavity, for example an optical fiber or a (particularly insulated) cable, the rupture of which can be detected by detecting an interruption in a light or current signal.

[0017] The term “top side” here refers to the outward-facing surface of a heat exchanger block, which is formed by one of its cover plates, and the “bottom side” refers to the outward-facing surface of the heat exchanger block, which is formed by the other cover plate. The top side and the bottom side can be parallel to one another and also parallel to the separating plates or the (largest) surfaces thereof and to the cover plates or the (largest) surfaces thereof. Depending on the type of production, however, such parallelism is not a mandatory requirement. The terms “in the direction of the top side” and “in the direction of the bottom side” refer to directions that are perpendicular to planes that are aligned parallel to the separating plates and cover plates or within which the separating plates and cover plates lie. The direction specified with regard to the width of the cavity extends in particular perpendicular to the directions in the direction of the top side and the bottom side.Bottom.

[0018] The orientation of the corresponding directions is indicated by specifying the target ("toward the top side" or "toward the bottom side"). Alternatively, both directions can also be defined as directions that are perpendicular to a plane spanned by a respective separating plate (or its surface) and oriented in opposite directions to each other.

[0019] Instead of the terms "top" and "bottom," the terms "first side" and "second side" can also be used, so that the term "toward the top" can also be used "toward the first side" or "in a first direction." The same applies to the term "toward the top," which can be replaced by "toward the second side" or "in a second direction." During operation of a corresponding heat exchanger block, the top and bottom sides can also be arranged at the front and back, left and right, etc., and should not be understood as restrictive.

[0020] In one embodiment of the invention, the first material layer can be formed by a first sheet and the second material layer by a second sheet, wherein the cavity in this case can be provided by a recess in a surface of the first sheet facing towards the second side and / or by a recess in a surface of the second sheet facing towards the first side. If corresponding recesses are provided in both sheets, these form the cavity, in particular together, and are aligned accordingly one above the other. In other embodiments, as mentioned, the first material layer and the second material layer can also be connected to one another via an intermediate layer, in particular an intermediate sheet, wherein a recess formed in the intermediate layer can define the cavity.

[0021] The first sheet and the second sheet can be (hard-)soldered 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 layer that may be present. The aforementioned recess(es) can be formed, in particular, by embossing or material removal, for example, laser ablation, milling, eroding, etc.

[0022] In this embodiment, a corresponding sheet metal arrangement comprises, in particular, between at least two of the heat exchanger passages, two sheets without a structural sheet arranged therebetween, which together form a separating sheet (in the form of a double sheet) and / or a corresponding sheet metal arrangement on the top side and / or on the bottom side of the heat exchanger block comprises, in particular, two sheets without a structural sheet arranged therebetween, which together form a cover sheet (in the form of a double sheet).

[0023] In such embodiments of the present invention, a double partition plate or cover plate is used as a leak detection structure, for example, to insert a hollow volume or a control volume dedicated below sidebars (as explained in detail below). The volume is, for example, pressure-monitored, so that a tear in one of the partition plates or cover plates, particularly in the area of ​​the sidebars, and a penetration or outflow of fluid can be detected via a pressure change in the control volume. The size of the volume and thus, for example, also the weakening of the sidebars is selected such that the double partition plate or cover plate with control volume below the sidebars has a similar or slightly lower mechanical stability than a single partition plate or cover plate.

[0024] In other embodiments of the invention, the first material layer and the second material layer can also be parts of a one-piece Meta II structure in which the cavity is formed or recessed. Thus, for example, a single separating sheet or cover sheet or a modified metal structure can be used in which a cavity has been introduced into the separating sheet using suitable manufacturing methods or which has been manufactured with a cavity using suitable manufacturing methods (e.g., casting, any type of additive manufacturing process). Combinations of double sheets and single sheets can also be used.

[0025] The present invention enables leaks and other damage such as cracks to be detected early and reliably. For example, in contrast to the prior art discussed above, the solution proposed by the invention can be implemented more simply and requires less space.

[0026] The quantity that correlates with a rupture of a wall of the cavity or of an element arranged in the cavity can, in an already discussed embodiment of the invention, be a quantity that characterizes an inflow of fluid into the cavity and / or an outflow of fluid from the cavity. In relation to corresponding embodiments, it is referred to below as a pressure in the cavity, which increases when fluid flows into the cavity and decreases when fluid flows out of the cavity. In such embodiments, however, the cavity can also be monitored using measuring methods based on optical, magnetic, electromagnetic, or acoustic effects. The physical effects being monitored can require the introduction of suitable transmission materials (e.g., fiber optics). Reference is made below to a pressure value only for the sake of simplicity.

[0027] In one embodiment of the present invention, the measuring device has a computing unit or is connected or connectable to a computing unit, wherein the computing unit is configured to monitor the variable, for example the pressure in the cavity, an electrical signal, an optical signal, or the like, and is further configured to detect a leak in the heat exchanger block or a rupture in one of the aforementioned structures based on this monitored variable. Corresponding leak detection can, for example, be based on a threshold value comparison and comprise any desired signal processing method, for example determining a moving average to eliminate short-term fluctuations in the variable. Alternatively or additionally, data-driven models and machine learning methods can also be used in this context.

[0028] In embodiments of the present invention, if corresponding double sheets (with a first and a second sheet) are used, the cavity can be formed by a recess, as mentioned, in one of these sheets or by mutually facing recesses in both sheets. In the first alternative, for example, only one of the sheets needs to be weakened or extensively machined, whereas in the second alternative, a larger cavity can be created. With a recess in an intermediate sheet, the upper and lower sheets remain unweakened.

[0029] In embodiments of the present invention, the cavity in the leak detection structure can run alternately on two sides of a center line. This can, in particular, be a meandering or zigzag-shaped channel. The center line can, in particular, lie parallel between an upper side and a lower side of the respective leak detection structure. As mentioned, parallelism is not required, however. In an embodiment with two metal sheets, one recess or at least one of the recesses facing one another in the two metal sheets can run alternately on two sides of a corresponding center line, at least in one section. As explained in more detail below with reference to Figure 3, crack propagation can be limited in this way. In this case, an embodiment in which the center line runs parallel to a side edge of the respective separating plate and / or cover plate can be advantageous.However, this is not mandatory. However, it can also be provided that the center line (instead) runs parallel or in another suitable orientation to a predicted crack propagation line or an area of ​​expected crack initiation. The area of ​​expected crack initiation can be determined, for example, through simulations.

[0030] The recess or a corresponding cavity in general, which runs alternately on two sides of a center line at least in one section, can, in embodiments of the present invention, run in a meandering, sinusoidal, undulating, or zigzag shape, in particular in a plane parallel to the top and bottom of the leak detection structure and thus parallel to the first and second sides of the heat exchanger block or the separating and cover plates. However, other suitable orientations are also possible here at any time. The choice made in each case can be based in particular on simplifying production or mechanical strength. In particular, the width of a corresponding amplitude parallel to the first and second material layers is smaller than the width of the structural plates in this direction.

[0031] In one embodiment of the present invention, sidebars can be arranged on two sides of the central structured sheet(s) in the heat exchanger passages. In a vertical projection onto a plane arranged in particular (but not necessarily) parallel to the first and second side of the heat exchanger block or the separating structures and cover structures or their surface(s), the projection surfaces of the separating structures and the cover structures overlap in particular essentially completely. Corresponding projection surfaces of the sidebars overlap with peripheral regions of the separating structures and the cover structures or their projection surfaces, as is usual in this respect with plate-fin heat exchangers. In a corresponding vertical projection, a transition region between at least one of the sidebars and at least one of the structured sheets can overlap with the cavity in at least one section.The transition region can, in particular, be a substantially straight line at which a sidebar abuts the corresponding structured sheet of the heat exchanger passage. Such a line can therefore intersect a projection surface of the cavity in a corresponding vertical projection. Such an arrangement can, in particular, ensure that the particularly leak-prone regions in the transition region between sidebars and structured sheets, or the region of the separating and cover sheets covered thereby, can be provided with the leak detection options provided according to the invention. However, alternative embodiments are also possible in which, in the aforementioned vertical projection, either only the projection surfaces of at least one of the sidebars or only at least one of the structured sheets intersect with the projection surface of the cavity.

[0032] In one embodiment of the present invention, the cavity can be connected to a drainage device to ensure the outflow of fluid in the event of any leaks and thus prevent, for example, excess pressure. A corresponding drainage device can also be configured, for example, for an opening above a predetermined pressure threshold.

[0033] In a fin-plate heat exchanger according to an embodiment of the present invention, it can be provided that temperature detection means or any other measuring means for detecting a temperature or any other measured values ​​are introduced into the heat exchanger block.

[0034] In a plate-fin heat exchanger of the type described, in a similarly already discussed embodiment of the invention, a structure such as an insulated cable or a fiber optic cable for crack detection can be arranged in the cavity or at any other location. This structure is attached in such a way that it is interrupted upon the occurrence of a crack. A resistance value or a current flow through the cable can be monitored, so that a corresponding interruption can (additionally) be inferred to be a crack. Thus, a value is detected that correlates with a rupture of an element arranged in the cavity. The rupture, as mentioned, can be detected by detecting an interruption in a light or current signal.

[0035] In embodiments of the present invention, in addition to the cavity formed in the manner described, a further cavity of the same or different design can be arranged in the leak detection structure, wherein the cavities can be arranged in the leak detection structure without any mutual connection to one another. Sections of the two cavities can be arranged opposite one another or can alternately intersect an axis.

[0036] A method for producing a plate-fin heat exchanger having a heat exchanger block is also subject of the present invention. The method comprises forming a stack arrangement comprising a number of heat exchanger passages, wherein the heat exchanger passages are each formed by arranging a number of distribution and collection structures and central structured sheets, wherein separating structures are arranged between the heat exchanger passages, and wherein a cover structure is arranged on a first side and a second side of the stack arrangement. The method further comprises connecting the stack arrangement to form a heat exchanger block.

[0037] According to the invention, at least one of the separating structures and / or at least one of the covering structures is provided as a leak detection structure with a cavity which is arranged in the leak detection structure in such a way that the cavity is delimited in the direction of the first side by a first material layer and in the direction of the second side by a second material layer of the leak detection structure, wherein the first material layer and the second material layer are connected to one another in a region of the leak detection structure not occupied by the cavity. A width of the cavity in a direction parallel to the first and second material layer is less than a width of the central structured sheets of the heat exchanger passages in the same direction, ie of one or more structured sheets in one or more of the heat exchanger passages.Furthermore, provision is made of a measuring device configured to detect a variable that correlates with a rupture of the cavity or an element arranged in the cavity. The method can, in particular, comprise the provision of the features explained in detail above according to the various embodiments of the present invention.

[0038] The invention also relates to a method for controlling the temperature of at least one fluid, in which a plate-fin heat exchanger is used, as previously explained in embodiments.

[0039] With regard to the features and advantages of the methods and embodiments thereof, reference is expressly made to the above explanations of the plate-fin heat exchanger according to the invention and its embodiments, since these relate to the methods carried out in each case and the corresponding process products in the same way.

[0040] The invention is explained in more detail below with reference to the accompanying drawings, which illustrate embodiments of the present invention.

[0041] Brief description of the drawings Figure 1 illustrates a plate-fin heat exchanger

[0042] Figure 2 illustrates aspects of an embodiment of the present invention.

[0043] Figure 3 illustrates aspects of an embodiment of the present invention.

[0044] Figure 4 illustrates aspects of an embodiment of the present invention.

[0045] Figure 5 illustrates aspects of an embodiment of the present invention.

[0046] Figure 6 illustrates aspects of an embodiment of the present invention.

[0047] Figure ? illustrates aspects of an embodiment of the present invention.

[0048] Detailed description of the drawings

[0049] In the figures, identical reference numerals are used for structurally and / or functionally corresponding elements. Such elements will not be explained repeatedly. Where device features are explained below, the corresponding explanations apply to method steps in the same way, and vice versa.

[0050] Brazed aluminum plate-fin heat exchangers are shown and described in Figure 2 of the aforementioned ISO 15547-2:3005 and on page 5 of the ALPEMA publication "The Standards of the Brazed Aluminum Plate-Fin Heat Exchanger Manufacturers' Association," 3rd edition 2010. A diagram that essentially corresponds to the figures therein is shown in the attached Figure 1 and is explained below. The plate heat exchanger 100, shown partially open in Figure 1, serves for the heat exchange of five different process media A to E in the example shown.

[0051] For heat exchange between the process media A to E, the plate heat exchanger 100 comprises a plurality of partition plates 4 arranged parallel to one another (referred to in English as parting sheets in the aforementioned publications, to which the following information in brackets also refers, and here also as separating structures), between which heat exchange passages 1 are formed, defined by structured plates 3 with fins, for each of the process media A to E, which can thereby enter into heat exchange with one another.

[0052] The structured sheets 3 are typically folded or corrugated, with the folds or corrugations forming flow channels, as shown in Figure 1 of ISO 15547-2:3005. The provision of the structured sheets 3 offers the advantage of improved heat transfer, more targeted fluid guidance, and increased mechanical (tensile) strength. In the heat exchange passages 1, the process media A to E flow separately from one another, particularly through the separating sheets 4, but can possibly pass through the latter in the case of perforated structured sheets 3.

[0053] The individual passages 1 are each surrounded laterally by so-called sidebars 8, which, however, leave open feed and discharge openings 9. The sidebars 8 keep the separating plates 4 at a distance and provide mechanical reinforcement for the printing chamber. Reinforced cover plates 5 (cap sheets), arranged parallel to the separating plates 4, serve to seal off at least two sides.

[0054] By means of so-called headers 7, which are equipped with nozzles 6, the process media A to E are fed in and out via feed and discharge openings 9. In the inlet area of ​​the passages 1, there are further structured plates 2 with so-called distributor fins, which ensure even distribution across the entire width of the passages 1. Viewed in the direction of flow, at the end of the passage 1, there may be further structured plates 2 with collecting fins, which guide the process media A to E from the passages 1 into the headers 7, where they are collected and withdrawn via the corresponding nozzles 6. In this case, we also refer to "distributor and collecting structures".

[0055] The structured sheets 2 and 3, the sidebars 8, the separating sheets 4, and the cover sheets 5 form a cuboid-shaped heat exchanger block 10. A "heat exchanger block" is understood here to mean the aforementioned elements without the headers 7 and nozzles 6 in an interconnected state. The top side or first side is referred to as the outward-facing surface of the heat exchanger block 10, which is formed by one cover sheet 5, and the bottom side or second side is referred to as the outward-facing surface of the heat exchanger block 10, which is formed by the other cover sheet 5. In Figure 1, the top side or first side is designated by U, while the bottom side or second side is concealed and indicated by L. Although not illustrated in Figure 1, the plate heat exchanger 100 can be formed from several cuboid-shaped and interconnected heat exchanger blocks 10, particularly for manufacturing reasons.

[0056] Plate heat exchangers 100 are brazed from aluminum, for example. The passages 1, comprising the structured sheets 2 and 3, the separating sheets 4, the cover sheets 5, and the sidebars 8, are each coated 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 onto the heat exchanger block 10 thus produced.

[0057] Figure 2 illustrates a structure according to an embodiment of the present invention and is designated overall by 20. The structure 20 represents part of a heat exchanger block 10 illustrated in Figure 1, wherein the respective elements are not drawn to scale and are illustrated in cross-section between the top or first side U and the bottom or second side L. The sidebars 8 are not shown here. The arrangement continues downwards essentially in the same way, as indicated by ellipses (...) in Figure 2. Any other continuation is also possible. So-called dummy layers (passages through which no flow occurs) can also be provided. These can also be located at the outer end of the active passages and adjacent to the cover plates.

[0058] As illustrated by the arrangement 20, heat exchanger passages, which were previously designated 1, are arranged in the heat exchanger block previously designated 10. The structured sheets 3 of these are shown in Figure 2. As illustrated in Figure 2, two separating sheets 41, 42 are arranged between the heat exchanger passages 1 and the structured sheets 3, which, as illustrated with reference to the following figures, form a leak detection structure 11. Furthermore, the heat exchanger block 10, in the embodiment illustrated here, is covered on its top side or first side U by two cover sheets 51, 52. These also form a leak detection structure, which, as illustrated with reference to the following figures, also form a leak detection structure, which, for the sake of simplicity, is also designated 11. The underside or second side L can be designed in a corresponding manner. In other words, double separating or cover sheets 41, 42 and51, 52, each forming leak detection structures 11.

[0059] In the following, features of embodiments of the present invention are illustrated with reference to Figures 2 to 5 using separating plates 41, 42. The cover plates 51, 52 can each be designed in the same or comparable manner and are not explained in detail for the sake of clarity.

[0060] In Figure 4, which will now be described in advance, a corresponding structure 20 is illustrated again, but here, in addition to the structured sheets 3, the sidebars 8 are also shown.

[0061] As can be seen from Figure 4 or the arrangement illustrated here, two separating plates 41, 42 are arranged between at least two of the heat exchanger passages 1 without a structural plate 3 arranged therebetween, which form the leak detection structure 11, and a cavity 43 is arranged between the two separating plates 41, 42.

[0062] Furthermore, a measuring device is provided, which in the example illustrated here comprises a sensor 45, a measuring cable 46, and a computing unit 50. This is configured to measure a pressure in the cavity 43, evaluate it in the manner explained, and thus detect a leak.

[0063] As can be seen from Figure 4, the cavity 43 is delimited in the direction of the top side or first side U by an upper or first material layer 41a and in the direction of the bottom side or second side L by a lower or second material layer 42a of the leak detection structure 11, wherein the upper or first material layer 41a is formed by an upper or first metal sheet 41 and the lower or second material layer 42a is formed by a lower or second metal sheet 42. The cavity 43 is formed here by a recess in a surface of the upper or first metal sheet 41 facing in the direction of the bottom side or second side L and by a recess in a surface of the lower or second metal sheet 42 facing in the direction of the top side U or first side, which are in particular placed one on top of the other with a precise fit.

[0064] A width of the cavity 43 in a direction parallel to the first and second material layers 41a, 42b, ie here horizontally in the plane of the drawing, is smaller than a width of the structured sheets 3 in the same direction.

[0065] As can also be seen from Figure 4 and illustrated by a dash-dotted line, which in itself does not represent a structural element, in a vertical projection onto a plane parallel to the top side U and the bottom side L, a transition region, delineated by the dash-dotted line, between at least one of the sidebars 8 and at least one of the structured sheets 3 overlaps in at least one section with the cavity 43 or its projection surface. Alternative embodiments are possible in which, in the vertical projection mentioned, either only at least one of the sidebars 8 or only at least one of the structured sheets 3 overlaps with the cavity 44 or its projection surface. These alternatives, which are not realized according to Figure 4, are each illustrated in the form of dotted ovals.

[0066] This arrangement is further illustrated in Figure 5, where corresponding projections onto a plane corresponding to the plane of the paper are shown. A portion of the projection area of ​​the sidebar is indicated here by 8', a portion of the projection area of ​​the first or second sheet by 4', and a portion of the projection area of ​​the cavity, which is assumed to be straight, by 43'. The width of the cavity 43 in a direction parallel to the first and second material layers 41a, 42b is also horizontal in the plane of the drawing.

[0067] In Figure 3, which will now be described, a corresponding top or bottom sheet 41 or 42 is illustrated in a partial perspective view, wherein the axis shown in dash-dotted lines, which runs parallel to the plane of the paper, indicates the direction in which the explained width of the cavity lies.

[0068] As already illustrated in Figure 4, the cavity 43 can be formed by a recess in one of the sheets 41, 42 or 51, 52 or by mutually facing recesses in the respective sheets 41, 43 or 51, 52. Such recesses are designated 44 in Figure 3. Of course, a plurality of recesses 44, which can be formed in the sheets 41, 42 or 51, 52, can also be provided. The recesses 44 can be provided, for example, by milling, embossing or applying material at other locations. As mentioned, however, within the scope of the present invention, a single metal structure with a cavity 43 can also be provided, wherein the cavity can be recessed or formed in the metal structure, for example, by casting, additive manufacturing or other methods. In the following, two separating sheets 41, 42 are referred to without any intended restriction.The corresponding explanations also apply in the same way to a cavity formed or recessed in a metal structure.

[0069] As mentioned, one recess 44 or at least one of the mutually facing recesses 44 in the two separating plates 41, 42 can, at least in one section, run alternately on two sides of a center line M and lie in a plane parallel to the top and bottom of the corresponding plate. This is illustrated in Figure 6 with a section 44a in which the recess runs in a meandering shape, whereas on an opposite side of the separating plate 41, 42 it runs straight.

[0070] In an embodiment illustrated in Figure 7, at least sections 44b, 44c are formed that are interlaced without any intermediate connection, thus providing two independent monitoring circuits. These can be formed, for example, in a straight or meandering shape.

[0071] As mentioned several times, but not separately illustrated here for reasons of clarity, an element or a structure in the form of a particularly insulated cable or optical fiber can also be introduced into the cavity 43, the rupture of which can be detected by evaluating an optical signal or current signal.

Claims

A fin-plate heat exchanger (100) with a heat exchanger block (10), wherein heat exchanger passages (1) are arranged in the heat exchanger block (10), each having distributor and collector structures (2) and one or more central structured sheets (3) arranged between the distributor and collector structures (2), wherein separating structures (41, 42) are arranged between the heat exchanger passages (1), and the heat exchanger block (10) is covered on a first side (II) and a second side (L) by cover structures (51, 52), characterized in that at least one of the separating structures (41, 42) and / or at least one of the cover structures (51, 52) is designed as a leak detection structure (11) having a cavity (43) formed in the leak detection structure (11) in such a way thatthat it is delimited in the direction of the first side (U) by a first material layer (41a) and in the direction of the second side (L) by a second material layer (42a) of the leak detection structure (11), wherein in a region of the leak detection structure (11) that is not occupied by the cavity (43), the first material layer (41a) and the second material layer (42a) are connected to one another, that a width of the cavity (43) in a direction parallel to the first material layer (41a) and the second material layer (42a) is less than a width of the central structured sheet(s) (3) of the heat exchanger passages in this direction, and that a measuring device (45, 46, 50) is provided that is designed to detect a value that correlates with a rupture of a wall of the cavity (43) or of an element arranged in the cavity (43). A fin-plate heat exchanger (100) according to claim 1, wherein the size,which correlates with a rupture of a wall of the cavity (43) or of an element arranged in the cavity (43), is a quantity that characterizes an inflow of fluid into the cavity (43) and / or an outflow of fluid from the cavity (43). A plate-and-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 formed by, a recess (44) is provided in a surface of the first sheet (41) facing in the direction of the second side (L) and / or by a recess (44) in a surface of the second sheet (42) facing in the direction of the first side (II). The fin-and-plate heat exchanger (100) according to claim 3, wherein the recess (44) is formed by embossing or material removal. The fin-and-plate 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 in which the cavity (43) is formed or recessed. The fin-and-plate heat exchanger (100) according to claim 5, wherein the Meta II structure is formed using an additive manufacturing process.The fin-and-plate heat exchanger (100) according to one of the preceding claims, wherein the quantity that correlates with a rupture of a wall of the cavity (43) or of an element arranged in the cavity (43) is a pressure in the cavity. The fin-and-plate heat exchanger (100) according to one of the preceding claims, wherein the measuring device (45, 46, 50) comprises a computing unit (50) or is connected or connectable to a computing unit (50), wherein the computing unit (50) is configured to monitor the quantity that correlates with a rupture of a wall of the cavity (43) or of an element arranged in the cavity (43), and is further configured to detect a leak in the heat exchanger block (10) based on the monitored quantity. A fin-plate heat exchanger (100) according to any one of the preceding claims, wherein the cavity in the leak detection structure (11) extends alternately on two sides of a center line.A plate-fin heat exchanger (100) according to claim 9, wherein the center line extends in a predetermined arrangement to a side edge of the leak detection structure. The fin-and-plate heat exchanger (100) according to claim 9 or 10, wherein the center line runs in a predetermined orientation relative to a predicted crack propagation line and / or an expected crack formation region, and / or wherein the cavity (44), which runs alternately on two sides of a center line at least in one section, runs in a meandering, sinusoidal, undulating, or zigzag manner. The fin-and-plate heat exchanger (100) according to one of the preceding claims, wherein sidebars (8) are arranged on two sides of the central structured sheet(s) (3) in the heat exchanger passages (1), wherein, in a vertical projection onto a plane parallel to the first side (II) and the second side (L), a transition region between at least one of the sidebars (8) and at least one of the structured sheets (3) overlaps with the cavity (43) in at least one section.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 temperature sensing means for sensing a temperature are incorporated into the heat exchanger block (10), and / or wherein a cable for crack detection is arranged in the cavity. A method for producing a plate-fin heat exchanger (100), comprising the following steps: a) forming a stack arrangement comprising a number of. Heat exchanger passages, wherein the heat exchanger passages are each formed by arranging a number of distribution and collection structures (2) and central structured sheets (3), wherein separating structures (41, 42) are arranged between the heat exchanger passages, and wherein a cover structure (51, 52) is arranged on a first side (II) and a second side (L) of the stack arrangement, and b) connecting the stack arrangement to form a heat exchanger block (10), characterized by the following steps: c) providing at least one of the separating structures (41, 42) and / or at least one of the cover structures (51, 52) as a leak detection structure (11) with a cavity (43) arranged in the leak detection structure (11) such that the cavity (43) is delimited in the direction of the first side (II) by a first material layer (41a) and in the direction of the second side (L) by a second material layer (42a) of the leak detection structure (11), wherein in a region of the leak detection structure (11) not occupied by the cavity (43), the first material layer (41a) and the second material layer (42a) are connected to one another and a width of the cavity (43) in a direction parallel to the first material layer (41a) and the second material layer (42a) is smaller than a width of the central structured sheets (3) of the heat exchanger passages in the same direction, and d) providing a measuring device (45, 46, 50) configured to detect a value associated with a rupture of a wall of the cavity (43) or of a the element arranged in the cavity (43),which characterizes an inflow of fluid into the cavity (43) and / or an outflow of fluid from the cavity (43). A method for controlling the temperature of at least one fluid, in which a fin-plate heat exchanger (100) according to one of claims 1 to 13 is used.

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