Plate fin heat exchanger, method for manufacturing a plate fin heat exchanger, and method of using a plate fin heat exchanger

Abstract

A plate-fin heat exchanger (100) having a heat exchanger block (10) is proposed, in which a heat exchanger passage (1) is arranged having a distribution structure and a collection structure (2) respectively, and one or more central structured sheets (3) arranged between the distribution structure and the collection structure (2), a separation structure (41, 42) is arranged between the heat exchanger passages (1), and the heat exchanger block (10) is covered by covering structures (51, 52) on a first side (U) and a second side (L). In the present specification, at least one of the separation structures (41, 42) and / or at least one of the covering structures (51, 52) is designed as a leak detection structure (11), which has a cavity (43) formed therein, where the cavity (43) is separated in the direction of the first side (U) by a first material layer (41a) of the leak detection structure (11) and in the direction of the second side (L) by a second material layer (42a) in such a manner that in the 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 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 or sheets (3) of the heat exchanger passage in this direction, and measuring devices (45, 46, 50) are provided which are designed to detect a variable correlated with the breakage of the wall of the cavity (43) or an element arranged in the cavity (43). The present invention also relates to a method for manufacturing a corresponding plate-fin heat exchanger (100) and a method in which a plate-fin heat exchanger (100) of this type is used.

Description

Technical Field

[0001] The present invention relates to a plate-fin heat exchanger, a method for manufacturing a corresponding plate-fin heat exchanger, and a method in which a corresponding plate-fin heat exchanger is used.

Background Art

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

[0003] The above-mentioned plate heat exchanger is significantly different from a printed circuit heat exchanger (PCHE) type heat exchanger in terms of its design. The latter is a compact plate heat exchanger and usually has a core made of metal plates with chemically etched flow channels. After the flow channels are formed, the metal plates are placed on top of each other in an accurately fitting manner and then joined by diffusion welding to form a solid metal block.

[0004] For example, International Publication No. 97 / 03281 (A1) proposes to advantageously use such a printed circuit heat exchanger in the operation of a gas turbine. The gas turbine is provided with a corresponding heat exchanger, where heat is removed from the compressed air used to cool the turbine section by being taken out from the compressor section. The heat exchanger transfers the heat from the cooling air to the fluid that is injected back into the combustion section of the gas turbine, such as fuel, without using an intermediate heat transfer fluid. The heat removed from the cooling air is returned to the circuit when the fluid is introduced into the combustion chamber of the gas turbine.

[0005] The service life of the corresponding plate fin heat exchanger specifically depends on the generation of a strong heat gradient and the mechanical stress caused thereby. The structural weakening resulting from the mechanical stress accumulates and may ultimately lead to leakage on site. In plate fin heat exchangers, stress and leakage can specifically occur inside and outside the field of view, so there is a possibility that stress and leakage cannot be detected early enough. Leakage leads to an unplanned shutdown of the corresponding plant, which involves production losses and significantly increases the overall cost of corrective measures.

[0006] European Patent No. 3704431 (A1) proposes a plate fin fluid treatment device having an active layer, and each active layer comprises plate fins that are sandwiched between separation sheets such that an active fluid space is defined between the separation sheets. The active layer comprises the outermost active layer having an inlet and an outlet. The outermost active layer is followed by a layer structure having plate fins arranged between a separation sheet and a cap sheet. The layer structure has a sealed fluid space. A pressure monitoring system is connected to the fluid space of the layer structure. A pressure relief device is designed to relieve the pressure in the fluid space when a preset pressure is exceeded.

[0007] The object of the present invention is to improve the detection of leakage in a plate fin heat exchanger of the type described. SUMMARY OF THE INVENTION

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

[0009] According to the invention, a plate-fin heat exchanger having a heat exchanger block is proposed, in which heat exchanger passages each having, specifically in the form of a corresponding structured sheet, a distribution and collection structure and one or more central structured sheets arranged between the distribution and collection structures are arranged within the heat exchanger block, 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. The separation and covering structures can, on the one hand, be conventional separation or cap sheets, but any of these separation and covering structures can be a modified separation structure 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. Therefore, in an embodiment of the invention, at least one of the separation structures and / or at least one of the covering structures can be designed as a leak detection structure.

[0010] A corresponding leak detection structure is provided having a cavity formed within the leak detection structure, such that the cavity is delimited in the direction of the first side of the heat exchanger block by a first material layer of the leak detection structure and in the direction of the second side of the heat exchanger block by a second material layer of the leak detection structure. In embodiments of the invention, several cavities can be provided, and it should be understood that the following description applies to each cavity.

[0011] In the region 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 integrally joined together. However, an intermediate structure sheet in which an "active layer" is used is not provided, as in the case of, for example, European Patent Application Publication No. 3704431 (A1). In this way, the installation space is significantly reduced, and the manufacturing cost and labor are reduced. If the first material layer and the second material layer are not integrally formed, they can be in direct contact with each other, so they can be separated from each other only by a solder layer. Alternatively, in the region of the cavity, an intermediate layer having a recess defining the cavity can also be provided.

[0012] The width of the cavity in the direction parallel to the first and second material layers is less than the width of the central structured sheet of the heat exchanger passage in the same direction, specifically, less than the total width. "Width" specifically represents the minimum extent in the corresponding direction. Specifically, it is a dimension perpendicular to the longitudinal extent. Specifically, it is less than 1 / 50, 1 / 10 or 1 / 5 of the width of the structured sheet, and for example, more than 1 / 100. For example, in the case of a meandering, sine wave, or other periodic configuration, the amplitude in the above-mentioned direction can be correspondingly smaller than the width of the structured sheet.

[0013] Furthermore, it is intended that a measuring device is provided that is designed to detect a variable correlated with the breakage of the cavity wall or an element arranged within the cavity. A corresponding breakage in the wall can specifically allow fluid to flow into the cavity and / or fluid to flow out of the cavity, in which case a pressure loss or pressure increase can, in particular, characterize the corresponding breakage and can be detected in a corresponding embodiment of the present invention. In other embodiments of the present invention, a structure, such as an optical waveguide or a (specifically insulated) cable, can be introduced into the cavity, and its breakage can be detected by detecting the interruption of an optical or electrical current signal.

[0014] As understood herein, the term "upper side" refers to the outer surface of the heat exchanger block formed by one of the cap sheets, and the term "lower side" refers to the outer surface of the heat exchanger block formed by the other cap sheet. The upper side and the lower side can be parallel to each other and can be parallel to the separation sheet or its (maximum) surface and the cap sheet or its (maximum) surface. Depending on the type of production, such parallelism is not an essential requirement. The terms "in the direction of the upper side" and "in the direction of the lower side" refer to a direction perpendicular to the plane aligned parallel to the separation sheet and the cap sheet, or the direction in which the separation sheet and the cap sheet are located internally. The direction indicated with respect to the width of the cavity extends specifically perpendicular to the directions of the upper side and the lower side.

[0015] The orientation of the corresponding direction is indicated by specifying the purpose (in the "direction of the upper side" or "direction of the lower side"). Alternatively, both directions can also be defined as directions that are each perpendicular to the plane spanned by the respective associated separation sheet (or its surface) and are oriented in opposite directions to each other.

[0016] The terms "first side" and "second side" can also be used instead of the terms "upper side" and "lower side", and thus the description "in the direction of the upper side" can also be replaced with "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 can be replaced with "in the direction of the second side" or "in the second direction". The upper side and the lower side can also be arranged in front and behind, left and right, etc. during the operation of the corresponding heat exchanger block and should not be understood as limiting.

[0017] In one embodiment of the present invention, the first material layer can be formed by the first sheet, and the second material layer can be formed by the second sheet. In that case, the cavity can be provided by a recess in the surface of the first sheet facing in the direction of the second side and / or by a recess in the surface of the second sheet facing in the direction of the first side. When corresponding recesses are provided in both sheets, they specifically form the cavity together, and thus one is aligned on top of the 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, specifically an intermediate sheet, and a recess formed in the intermediate layer can define the cavity.

[0018] The first sheet and the second sheet can be joined, soldered, or connected in other ways to each other in the region of the leak detection structure not occupied by the cavity. The same applies to any intermediate layer that may be present. The above-described recesses can specifically be formed by embossing or material removal, such as laser ablation, milling, erosion, etc.

[0019] In this embodiment, the corresponding sheet configuration thus specifically comprises, between at least two of the heat exchanger passages, two sheets between which no structural sheet is arranged, and they together form a separation sheet (in the form of a double sheet), and / or the corresponding sheet configuration on the upper side and / or lower side of the heat exchanger block specifically comprises two sheets between which no structural sheet is arranged, and they together form a cap sheet (in the form of a double sheet).

[0020] Thus, in such embodiments of the present invention, specifically, a double separation sheet or a cap sheet is used as a leak detection structure for inserting a hollow volume or a control volume, for example, in a dedicated manner under the sidebar (as will be explained in detail below). For example, the volume is pressure monitored, and thus a tear in one of the separation sheet or the cap sheet, particularly in the region of the sidebar, and the penetration or outflow of fluid can be detected via a pressure change within the control volume. The size of the volume, and thus, for example, the weakening of the sidebar, is selected such that a double separation sheet or a cap sheet having a control volume under the sidebar has a mechanical stability similar to or slightly lower than that of a single separation sheet or a cap sheet.

[0021] In other embodiments of the present invention, the first material layer and the second material layer can also be part of an integrally formed metal structure in which cavities are formed or cut out. For example, by a suitable manufacturing method, cavities can be introduced into the separation sheet, or a single separation sheet, or a cap sheet, or a modified metal structure manufactured with cavities by a suitable manufacturing method (for example, casting, any type of additive manufacturing method) can also be used. Combinations of double sheets and single sheets can also be used.

[0022] The present invention enables early and reliable detection of other damages such as leaks and cracks. For example, in contrast to the prior art described initially, the solution proposed according to the present invention can be implemented in a technically simpler manner with smaller space requirements.

[0023] In the embodiments of the present invention already described above, the variables correlated with the rupture of the cavity wall or the elements arranged within the cavity can be variables characterizing the inflow of fluid into the cavity and / or the outflow of fluid from the cavity. In connection with the corresponding embodiments, hereinafter, the pressure within the cavity is referred to, which increases when fluid flows into the cavity and decreases when fluid flows out of the cavity. However, in such embodiments, the cavity can also be monitored using measurement methods based on optical, magnetic, electromagnetic, or acoustic effects. The physical effects to be monitored may require the introduction of a suitable transmission material (for example, glass fiber). For the sake of simplicity only, hereinafter reference is made to one pressure value.

[0024] In one embodiment of the present invention, the measuring device has a computing unit, is connected to a computing unit, or can be connected, and the computing unit is designed to monitor variables such as the pressure within the cavity, electrical signals, optical signals, etc., and based on this monitored variable, is further designed to detect a leak within the heat exchanger block or a rupture in one of the above-described structures. The corresponding leak detection can be based on, for example, threshold comparison and can include any signal processing method, for example, the determination of a moving average to remove short-term fluctuations of the variable. Alternatively, or additionally, data-driven models and machine learning methods can also be used within this context.

[0025] In an embodiment of the present invention, when the corresponding double sheet (having a first and a second sheet) is used, the cavity can be formed by a recess in one of these sheets or by recesses in both sheets facing each other, as described above. In a first alternative, for example, only one of the sheets needs to be weakened or machined on a large scale, while in a second alternative, a larger cavity can be created. If there is a recess within the intermediate sheet, the upper and lower sheets remain non-weakened.

[0026] In an embodiment of the present invention, the cavities within the leak detection structure can extend alternately on both sides of the centerline. Specifically, it can be a channel that meanders or extends in a zigzag shape. The centerline can specifically be positioned parallel between the upper side surface and the lower side surface of each leak detection structure. However, as described above, parallelism is not required. In an embodiment having two sheets, at least one of the recesses, or at least one of the recesses facing each other in the two sheets, can extend alternately on both sides of the corresponding centerline in at least one section. As will be described in more detail with reference to FIG. 3 below, crack propagation can be restricted in this way. In that case, an embodiment where the centerline extends parallel to the side edges of each separation sheet and / or the cap sheet may be advantageous. However, this is not essential. However, it may also be possible to make the centerline extend parallel to (instead of) the predicted crack propagation line or the region of predicted crack formation, or in another suitable orientation. The region of predicted crack formation can be determined, for example, by simulation.

[0027] In at least one section, the recesses or corresponding cavities that extend alternately on both sides of the centerline are generally, in an embodiment of the present invention, specifically, in a plane parallel to the upper and lower side surfaces of the leak detection structure, and thus in a plane parallel to the first and second side surfaces of the heat exchanger block or the separation sheet and the cap sheet, and can extend in a meandering, sinusoidal, wavy, or zigzag pattern. However, in this case, other suitable orientations are always possible. The choice made in each case can specifically be based on the simplification of the manufacturing technique or the mechanical strength. Specifically, the width of the corresponding amplitude parallel to the first and second material layers is also smaller than the width of the structural sheet in this direction.

[0028] In one embodiment of the present invention, the side bars can be arranged on both sides of the central structured sheet within the heat exchanger passage. With respect to the heat exchanger block or the separation structure and the coating structure or the first and second side surfaces of their surfaces, specifically (although not necessarily), in the perpendicular projection onto a plane arranged in parallel, the projection surfaces of the separation structure and the coating structure substantially completely overlap, in particular. The corresponding projection surfaces of the side bars overlap with the peripheral regions of the separation structure and the coating structure or their projection surfaces, as is common for plate fin heat exchangers. In the corresponding perpendicular projection, the transition region 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 region can specifically be substantially straight where the side bar abuts against the corresponding structured sheet of the heat exchanger passage. Therefore, such a line can intersect the projection surface of the cavity in the corresponding perpendicular projection. Such an arrangement can specifically ensure that the particularly leak-prone region in the transition region between the side bar and the structured sheet, or the regions of the separation sheet and the cap sheet covered thereby, can be provided with the leak detection option according to the present invention. However, in the above-mentioned perpendicular projection, an alternative embodiment is also possible where only the projection surface of at least one of the side bars, or only at least one of the structured sheets, overlaps with the projection surface of the cavity.

[0029] In one embodiment of the present invention, in case any leakage occurs, to ensure that the liquid flows out, and thus, for example, to prevent overpressure, the cavity can be connected to a drain device. The corresponding drain device can also be designed, for example, for an opening exceeding a predetermined pressure threshold.

[0030] In a plate fin heat exchanger according to an embodiment of the present invention, it can be provided that temperature detection means or any other measurement means for detecting temperature or any other measurement value is incorporated within the heat exchanger block.

[0031] Furthermore, in the plate fin heat exchanger of the type described, in the embodiments of the present invention already described above, a structure such as an insulating cable or an optical fiber for crack detection can be arranged in the cavity or any other place, and this structure is fixed so as to be interrupted when a crack occurs. The resistance value or the flow of current through the cable can be monitored, and thus, if there is a corresponding interruption, this can (additionally) suggest a crack. This means that a variable correlated with the breakage of an element arranged in the cavity is detected, and the breakage can be detected by detecting the interruption of an optical or current signal, as described above.

[0032] In an embodiment of the present invention, in addition to the cavities formed in the manner described, further cavities of the same design or different designs can also be arranged in the leak detection structure, and the cavities can be arranged in the leak detection structure without being interconnected with each other. The two cavity sections can be arranged alternately with each other or can intersect alternately with the axis.

[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 includes forming a laminate assembly comprising a plurality of heat exchanger passages, each heat exchanger passage being formed by arranging a plurality of distribution and collection structures and a central structured sheet, a separation structure being arranged between each heat exchanger passage, and a covering structure being arranged on the first side and the second side of the laminate assembly, respectively. The method further includes connecting the laminate 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 coating structures is provided as a leakage detection structure having a cavity disposed therein, the cavity being delimited in the direction of a first side by a first material layer of the leakage detection structure and in the direction of a second side by a second material layer, and the first material layer and the second material layer being connected to each other in a region of the leakage detection structure not occupied by the cavity. The width of the cavity in a direction parallel to the first and second material layers is less than the width of the central structured sheet of the heat exchanger passage, i.e., the width of one or more structured sheets in one or more of the heat exchanger passages, in this same direction. Further, it is intended that a measuring device be provided that is designed to detect a variable correlated with the rupture of the cavity or an element disposed within the cavity. The method may specifically include providing the features described in detail above according to different embodiments of the present invention.

[0035] A method for controlling the temperature of at least one fluid, wherein a plate fin heat exchanger as described in the previous embodiments is used, is also a subject of the present invention.

[0036] Regarding the features and advantages of the above-described method and its embodiments, the above description of the plate fin heat exchanger according to the present invention and its embodiments is equally applicable to each method and corresponding product implemented, and thus those descriptions are clearly referred to.

[0037] The present invention will be described in more detail below with reference to the accompanying drawings that illustrate preferred embodiments of the present invention.

Brief Description of the Drawings

[0038]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0039] In the figures, elements corresponding to each other with respect to structure and / or function are denoted by the same reference numerals. Such elements are not repeatedly explained. When the features of the device are described below, the corresponding explanations are equally applicable to method steps, and vice versa.

[0040] The brazed plate fin heat exchanger made of aluminum is shown and described in FIG. 2 of ISO 15547-2:2005 mentioned above, and on page 5 of the ALPEMA publication "The Standards of Brazed Aluminum Plate-Fin Heat Exchanger Manufacturers’ Association", 3rd edition, 2010. An illustration substantially corresponding to that illustration is shown in the attached FIG. 1 and described below. The plate heat exchanger 100 shown partially open in FIG. 1 is used for heat exchange of five different process media A to E in the illustration shown.

[0041] For heat exchange between the process media A to E, the plate heat exchanger 100 includes a plurality of separation sheets 4 arranged parallel to each other (in the aforementioned publication, with subsequent references in parentheses, these are called "division sheets" and are also called division structures in this case), and between these, a heat exchange passage 1 defined by a structured sheet having fins 3 is formed for one of the process media A to E in each case, thereby enabling heat exchange with each other.

[0042] As also shown in Figure 1 of ISO 15547-2:2005, the structured sheet 3 is typically folded or corrugated, and the flow channels are formed by each fold or corrugation. The provision of the 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 - E flow specifically separated by the separation sheet 4, however, in the case of the perforated structured sheet 3, they can optionally pass through the latter.

[0043] Each individual passage 1 is surrounded on each side by something known as a side bar 8, which leaves free space for the supply and discharge openings 9. The side bar 8 holds the separation sheet 4 at a distance and ensures the mechanical reinforcement of the pressure chamber. Specifically, a reinforced covering sheet 5 ("cap sheet") is arranged parallel to the separation sheet 4 and is specifically used to close at least two sides.

[0044] The process media A - E are supplied and delivered via the supply and discharge openings 9 by means of a so - called header 7 equipped with nozzles 6. In the inlet region of the passage 1, there is a further structured sheet 2 having what is known as distribution fins, ensuring a uniform distribution across the entire width of the passage 1. As seen in the direction of flow, a further structured sheet 2 having collection fins can be positioned at the end of the passage 1, guiding the process media A - E from the passage 1 to the header 7, where the process media A - E are collected and recovered via the corresponding nozzles 6. Herein, they are also referred to as "distribution and collection structures".

[0045] In this case, the heat exchanger block 10, which is a cuboid, is generally formed by the structured sheets 2 and 3, the side bars 8, the separation sheet 4, and the cap sheets 5. The "heat exchanger block" should be understood in this specification as the above-described elements without the header 7 and the nozzle 6 in an interconnected state. As used in this specification, the "upper side surface" or the first side surface refers to the outward-facing surface of the heat exchanger block 10 formed by its cap sheet 5, and the "lower side surface" or the second side surface refers to the outward-facing surface of the heat exchanger block 10 formed by the other cap sheet 5. In FIG. 1, the upper side surface or the first side surface is marked as U, and the lower side surface or the second side surface is hidden and indicated by L. Although not illustrated in FIG. 1, the plate heat exchanger 100 can specifically be formed from several cubic and interconnected heat exchanger blocks 10 for manufacturing reasons.

[0046] The plate heat exchanger 100 is, for example, brazed from aluminum. The passages 1 comprising the structured sheets 2 and 3, the separation sheet 4, the cap sheets 5, and the side bars 8 are in this case each provided with solder, stacked one on top of the other or arranged accordingly, and heated in an oven. The header 7 and the nozzle 6 are welded to the heat exchanger block 10 manufactured in this way.

[0047] FIG. 2 illustrates a structure according to an embodiment of the present invention, designated as 20 as a whole. The structure 20 represents a part of the heat exchanger block 10 illustrated in FIG. 1, and each element is illustrated in a cross-section between the upper side surface or the first side surface U and the lower side surface or the second side surface L, not to scale. The representation of the side bar 8 is omitted in this specification. This arrangement continues downward in substantially the same manner as indicated by the ellipsis (...) in FIG. 2. Any other continuation is also possible. It is also possible to provide so-called dummy layers (passages where no flow occurs). They are present at the outer ends of the active passages and can also abut against the cap sheets.

[0048] As illustrated by configuration 20, the heat exchanger passage previously designated as 1 is disposed within the heat exchanger block previously designated as 10. Among them, the structured sheet 3 is shown in FIG. 2. As illustrated in FIG. 2, two separation sheets 41, 42 are disposed between the heat exchanger passage 1 or the structured sheet 3 and form a leak detection structure 11 as illustrated with reference to the following figures. The heat exchanger block 10 in the embodiment illustrated herein is further covered by two cap sheets 51, 52 on its upper side surface or the first side surface U. As illustrated with reference to the following figures, they also form a leak detection structure, also designated as 11 for simplicity. The lower side surface or the second side surface L can be designed accordingly. In other words, here, double separation sheets or cap sheets 41, 42 and 51, 52 each forming a leak detection structure 11 are disposed.

[0049] Hereinafter, the features of the embodiments of the present invention are illustrated with reference to FIGS. 2 to 5 using the separation sheets 41, 42. The cap sheets 51, 52 can each be designed in the same or equivalent manner and are not described in detail for clarity.

[0050] In FIG. 4 described above here, the corresponding structure 20 is illustrated again, and in this case, in addition to the structured sheet 3, a sidebar 8 is also shown.

[0051] As can be seen from FIG. 4 or the arrangement illustrated herein, the two separation sheets 41, 42 are disposed between at least two of the heat exchanger passages 1 without the structured sheet 3 being disposed therebetween, form a leak detection structure 11, and a cavity 43 is disposed between the two separation sheets 41, 42.

[0052] Furthermore, a measuring device is provided, which in the examples illustrated herein has a sensor 45, a measuring cable 46, and a computing unit 50. The latter is designed to detect the pressure within the cavity 43, evaluate it in the manner described, and thereby detect a leak.

[0053] As can be seen in FIG. 4, the cavity 43 is delimited on the upper side surface or in the direction of the first side surface U by the upper side surface of the leakage detection structure 11 or the first material layer 41a, and on the lower side surface or in the direction of the second side surface L by the lower side surface or the second material layer 42a. The upper side surface or the first material layer 41a is formed by the upper side surface or the first sheet 41, and the lower side surface or the second material layer 42a is formed by the lower side surface or the second sheet 42. The cavity 43 is, in this case, formed by a recess in the surface of the upper side surface or the first sheet 41 facing in the direction of the lower side surface or the second side surface L, and by a recess in the surface of the lower side surface or the second sheet 42 facing in the direction of the upper side surface U or the first side surface, and these are, specifically, in an exactly fitting manner, with one arranged above the other.

[0054] The width of the cavity 43 in a direction parallel to the first and second material layers 41a, 42b, that is, in a direction horizontal in the plane of the drawing here, is smaller than the width of the structured sheet 3 in the same direction.

[0055] As also seen in FIG. 4 and as illustrated by the dashed line which does not itself represent a structural element, in the perpendicular projection onto a plane parallel to the upper side surface U and the lower side surface L, the transition region between at least one of the sidebars 8 where the dashed line hits and at least one of the structured sheets 3 overlaps with the cavity 43 or its projection surface in at least one section. Alternative embodiments are possible where 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 in the above-mentioned perpendicular projection. These alternative forms not realized according to FIG. 4 are each illustrated in the form of a dotted ellipse.

[0056] This arrangement is additionally illustrated in FIG. 5, where the corresponding projection onto a plane corresponding to the plane of the paper is shown. A part of the projection surface of the side bar is here illustrated as 8', a part of the projection surface of the first or second sheet is illustrated as 41', and a part of the projection surface of the cavity is here assumed to be straight and is illustrated as 43'. The width of the cavity 43 in a direction parallel to the first and second material layers 41a, 42b is here, specifically, horizontal in the plane of the drawing.

[0057] In FIG. 3, which will be described next, the corresponding upper side sheet 41 or lower side sheet 42 is illustrated in a partial perspective view, and in this case, the axis indicated by a dashed-dotted line extending parallel to the plane of the paper indicates the direction in which the width of the cavity to be described is located.

[0058] As already illustrated in FIG. 4, the cavity 43 can be formed by a recess in one of the sheets 41, 42 or 51, 52, or by recesses in the respective sheets 41, 43 or 51, 52 facing each other. Such a recess is designated as 44 in FIG. 3. Of course, several recesses 44 can also be provided that can be formed within the sheets 41, 42 or 51, 52. The recess 44 can be provided, for example, by milling, embossing, or applying material to other locations. As described above, not only a metal structure provided within the scope of the present invention, but also a single metal structure having a cavity 43 can be provided, and the cavity can be cut out or formed within the metal structure, for example, by casting, additive manufacturing, or other methods. In the following, two separate sheets 41, 42 are referred to without intending to be limiting. However, the corresponding explanations are equally applicable to cavities formed or provided within the metal structure.

[0059] As described above, at least one of the recesses 44 facing each other in one recess 44 or two separation sheets 41, 42 can extend alternately on two sides of the center line M in at least one section and be located in a plane parallel to the upper and lower side surfaces of the corresponding sheet. This is illustrated in FIG. 6 by section 44a, where the recess extends in a meandering manner, while on the opposite sides of the separation sheets 41, 42, the recess extends linearly.

[0060] In the embodiment illustrated in FIG. 7, at least sections 44b, 44c are formed, which are connected to each other without an intermediate connection, thereby providing two independent monitoring circuits. They can be, for example, linear or meandering.

[0061] Although not separately illustrated herein for clarity, as mentioned several times above, specifically, elements or structures in the form of insulated cables or optical fibers can also be introduced into the cavity 43, and their breakage can be detected by evaluating optical or electrical signals.

Claims

1. A plate fin heat exchanger (100) having a heat exchanger block (10), wherein heat exchanger passages (1) are arranged within 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), separation structures (41, 42) are arranged between the heat exchanger passages (1), the heat exchanger block (10) is covered on a first side (U) and a second side (L) by covering structures (51, 52), at least one of the separation structures (41, 42) and / or at least one of the covering structures (51, 52) is designed as a leak detection structure (11), which has a cavity (43) formed within the leak detection structure (11), where the cavity is located within the leak detection structure (11) A plate fin heat exchanger characterized in that the first material layer (41a) is separated in the direction of the first side (U) by the first material layer (42a) and the second material layer (42a) is separated in the direction of the second side (L) by the first material layer (43), the first material layer (41a) and the second material layer (42a) are connected to each other in the region of the leak detection structure (11) not occupied by the cavity (43), 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 this direction, and measuring devices (45, 46, 50) are provided, which are designed to detect a variable correlated with the rupture of the wall of the cavity (43) or an element located within the cavity (43).

2. The plate fin heat exchanger (100) according to claim 1, wherein the variable that correlates with the fracture of the wall of the cavity (43) or an element disposed within the cavity (43) is a variable that characterizes the inflow of fluid into the cavity (43) and / or the outflow of fluid from the cavity (43).

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

4. The plate fin heat exchanger (100) according to claim 3, wherein the recess (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 part of an integrally formed metal structure in which the cavity (43) is formed or provided.

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

7. The plate fin heat exchanger (100) according to claim 1 or 2, wherein the variable that correlates with the fracture of the wall of the cavity (43) or an element disposed within the cavity (43) is the pressure within the cavity.

8. The plate fin heat exchanger (100) according to claim 1 or 2, wherein the measuring devices (45, 46, 50) have, or are connected to, or can be connected to a calculation unit (50), the calculation unit (50) is designed to monitor the variables that correlate with the rupture of the walls of the cavity (43) or elements placed within the cavity (43), and is further designed to detect leakage within the heat exchanger block (10) based on the monitored variables.

9. The plate fin heat exchanger (100) according to claim 1 or 2, wherein the cavities within the leakage detection structure (11) extend alternately on both sides of the center line.

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

11. The plate fin heat exchanger (100) according to claim 9, wherein the center line extends in a predetermined orientation toward a predicted crack propagation line and / or region where crack formation is expected, and / or in at least one section, the cavities (43) extending alternately on both sides of the center line meander, sinusoidal, wave-shaped, or zigzag-shaped.

12. The plate fin heat exchanger (100) according to claim 1 or 2, wherein the side bars (8) are arranged on both sides of the central structured sheet (3) within the heat exchanger passage (1), and in a perpendicular projection onto a plane parallel to the first side (U) and the second side (L), the transition region between at least one of the side bars (8) and at least one of the structured sheet (3) overlaps with the cavity (43) in at least one section.

13. The plate fin heat exchanger (100) according to claim 1 or 2, wherein the cavity (43) is connected to a drainage device and / or a temperature sensing means for detecting temperature is incorporated into the heat exchanger block (10) and / or a cable for crack detection is located within the cavity.

14. A method for manufacturing a plate fin heat exchanger (100), a) A step of forming a laminate assembly having many heat exchanger passages, wherein each heat exchanger passage is formed by arranging many distribution and collection structures (2) and a central structuring sheet (3), and separation structures (41, 42) are each arranged between the heat exchanger passages, and covering structures (51, 52) are each arranged on the first side (U) and second side (L) of the laminate assembly, b) The step of connecting the laminated assemblies to form a heat exchanger block (10) and, c) Providing at least one of the separation structures (41, 42) and / or at least one of the covering structures (51, 52) as a leak detection structure (11) having a cavity (43) located within the leak detection structure (11), wherein the cavity (43) is located in the direction of the first side surface (U) by the first material layer (41a) of the leak detection structure (11) and in the direction of the second side surface (L) by the second material layer (42a) The steps to provide are: in a manner that the leak detection structure (11) is divided in the aforementioned direction, and in the 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 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 structural sheet (3) of the heat exchanger passage in the same direction; d) A method comprising the step of providing a measuring device (45, 46, 50) designed to detect a variable that correlates with the rupture of the wall of the cavity (43) or an element located within the cavity (43), characterizing the inflow of fluid into and / or outflow of fluid from the cavity (43).

15. A method for controlling the temperature of at least one fluid, wherein a plate fin heat exchanger (100) according to claim 1 or 2 is used.

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