EP4561738A2

EP4561738A2 - Stack of plates for a humidifier and humidifier

Info

Publication number: EP4561738A2
Application number: EP23742209.2A
Authority: EP
Inventors: Alexander Korn; Ralph Kemper; Tom Zeltwanger; Pius Trautmann; Markus Wagner
Original assignee: Mann and Hummel GmbH
Current assignee: Mann and Hummel GmbH
Priority date: 2022-07-28
Filing date: 2023-07-11
Publication date: 2025-06-04
Also published as: WO2024022798A2; DE102022118939A1; WO2024022798A3

Abstract

The invention relates to a stack of plates (400) for a humidifier (100), in particular for a fuel cell system, having a plurality of first and second support plates (100, 200) alternately following one another in a stack direction (500). First and second groups of flow ducts (410, 420) are designed in the stack of plates (400), each of which is separated by selectively permeable membranes (110, 210). Two successive first (100) and second support plates (200) in the stack direction (500) are in each case connected to one another in a fluid-tight manner by a connecting portion (150,250) on at least two first sides (124,224) opposing one another transversely to the stack direction, while an inflow and/or outflow area is designed between the support plates (100, 200) on at least two of its second sides (122,222) opposing one another transversely to the stack direction in each case. The connecting portions (150,250) are each formed by a double bead (152,252) on one of the support plates (100,200) and a corresponding single bead (160,260) on the other support plate (100,200), which is accommodated at least in the double bead (152,252). Furthermore, the invention relates to a humidifier (1000) for a fuel cell system.

Description

STACK OF PLATES FOR A HUMIDIFIER AND HUMIDIFIER

TECHNICAL FIELD

[0001] The invention relates to a stack of plates for a humidifier, in particular for a fuel cell system, as well as a humidifier for a fuel cell system itself.

BACKGROUND ART

[0002] Humidifiers for fuel cell systems are known from the background art in various embodiments, wherein a distinction is made between the two basic technologies of hollow fiber humidifiers on the one hand and flat membrane humidifiers on the other. Furthermore, certain types of fuel cell stacks are known that feature internal humidification and do not require a separate humidifier.

[0003] A humidifier is an indispensable feature of a fuel cell system, as it ensures that an electrolyte membrane used in the fuel cell stack is always present in a humidified state, ensuring that the electrolytes therein are in a hydrated state. If the electrolyte membrane of the fuel cell system is not sufficiently moist, the conductivity of the electrolyte decreases, which reduces the performance of the fuel cell. Therefore, in order to operate a fuel cell stack having optimal performance and/or efficiency, a humidifier is a core component.

[0004] All known humidifiers have in common that they humidify a dry cathode air stream leading to the fuel cell stack by supplying moisture to this dry air flow from a moist exhaust air flow coming from the fuel cell. Usually, the dry air flow leading to the fuel cell stack and the humid air flow coming from the fuel cell stack are guided in cross flow or reverse flow via a moisture-permeable membrane where the moisture transfer occurs.

[0005] Known flat membrane humidifiers feature a plurality of stacked frame plates that design a plurality of dry gas and humid gas ducts, each separated by a moisture-permeable membrane.

[0006] The membrane is hereby usually firmly connected, for example glued or welded, to the respective frame plates.

[0007] Humidifiers of this kind are known, for example, from DE 10 2016 014 895 A1 and DE 10 2019 123 534 A1.

[0008] DE 102013 020 503 A1 discloses a humidifier which is used to enrich flowing air, which is supplied for example to a fuel cell for the electrochemical reaction, with a defined moisture content. The humidifier features a stacking unit with several membranes disposed one above the other, preferably parallel and spaced apart from one another, each of which is permeable to water but not to air, wherein air flows having different moisture content are guided along the opposing sides of the membrane, so that a water or water vapor exchange takes place from the air flow having a higher moisture content to the air flow having a lower moisture content. The humidifier features the stacking unit in a housing with water-vapor permeable membranes which are disposed between frame parts. The housing features domes for supporting the stacking unit, wherein the connection between domes and the frame parts is realized via laterally projecting connecting tabs which extend into a receiving groove. [0009] Since both high thermal loads (in the form of the thermal energy contained in the exhaust gas flow) and mechanical loads (in the form of a pressure gradient acting via the membrane surface) occur during operation of the humidifier in a fuel cell system, the connection of the frame plates to one another represents a potential weak point that can lead to premature failure of the humidifier. Furthermore, the connection of the frame plates to each other has so far often been connected with a high proportion of manual operation, which is error-prone and expensive.

SUMMARY

[0010] One object of the invention is therefore to create a stack of plates for a humidifier, in particular for a fuel cell system, which features an improved thermal and mechanical load capacity and which can be manufactured in a process-reliable manner under a higher degree of automation.

[0011] This object is solved by a stack of plates having the features of independent claim 1. [0012] A further object is to provide a humidifier, in particular for a fuel cell system.

[0013] This object is solved by a humidifier having the features of independent claim 22.

[0014] Favorable embodiments and advantages of the invention will become apparent from the further claims, the description and the drawings.

[0015] The stack of plates for a humidifier, in particular for a fuel cell system, proposed according to a first aspect of the present invention comprises a plurality of first and second support plates alternately following one another in a stack direction, each plate featuring a peripheral frame surrounding an opening. First and second groups of flow ducts are designed in the stack of plates, each of which is separated by selectively permeable membranes, in particular to water-vapor permeable membranes. Three each of the first and second support plates alternately following one another form two of the flow ducts. In this connection, two successive first and second support plates following one another in the stack direction are in each case connected to one another in a fluid-tight manner by a connecting portion on at least two first sides opposing one another transversely to the stack direction, while an inflow and/or outflow area of the first group of flow ducts is designed on at least two of its second sides opposing transversely to the stack direction between the support plates. Furthermore, two successive second and first support plates following one another in the stack direction are in each case connected to one another in a fluid-tight manner by a connecting portion on at least two second sides opposing one another transversely to the stack direction, while an inflow and/or outflow area of the second group of flow ducts is designed on at least two of its first sides opposing transversely to the stack direction between the support plates. The connecting portions are each formed by a double bead on one of the support plates and a corresponding single bead on the other support plate, wherein the single bead is accommodated at least section-wise in the double bead.

[0016] The connecting portions designed between two adjacent support plates laterally limit a flow duct designed between them. In doing so, a cross section of the first support plate can be designed to be congruent with a cross section of the second support plate.

[0017] In this way, the first and second support plates can be stacked alternately closely and thus form flow ducts disposed transversely to one another. Using the corresponding single and double beads, an adhesive gap can be set between the stacked support plates, which enables a corresponding sealant to be metered in automatically and in a process-reliable manner. Thanks to an adhesive bond, the stacked support plates can be securely connected and form tight flow ducts. Furthermore, thanks to the bead structure proposed according to the invention, significant stiffening of the individual support plates is achieved, so that as a result the entire stack of plates is stiffened and thus deforms less under exterior forces, which is favorable to a permanent tightness of the stack of plates.

[0018] The proposed stack of plates is advantageously suitable for a flat membrane humidifier. In doing so, the flow ducts, for example exhaust gas duct and supply air duct, are each formed using two support plates and serve to allow moisture-laden exhaust gas to flow through in the exhaust gas duct, for example from a fuel cell, and in the neighboring flow duct using dry inlet air for the fuel cell. Thanks to the selectively permeable membrane, the inlet air can be humidified by moisture from the exhaust gas.

[0019] In embodiments, the first and second support plates can be structurally different and can differ in particular in dimensions, shape and/or arrangement of the single and/or double beads. In other embodiments, however, the first and the second support plates can also be structurally identical but installed in adjacent stack layers of the stack of plates in a respective rotated orientation, in particular rotated by 90° or 180°, in order to be able to fulfill their intended function in forming the flow ducts. The support plates can each have a polygonal, in particular rectangular, shape. In a particular embodiment, a rectangular shape can also have a square shape, which offers the potential for using identical parts for the first and second support plates.

[0020] The selectively permeable membrane separates the exhaust gas flow ducts from the inlet air flow ducts. The selectively permeable membrane can be designed for example as a PFSA (perfluorosulfonic acid) membrane, also known as a Nation membrane. Such membranes are also commonly used as proton exchange membranes. The membrane is in particular air-tight but moisture permeable. The selectively permeable membrane completely covers the opening provided in the support plates so that a moisture transfer surface is provided in the area of the opening.

[0021] The first and second sides of the support plates can each be present in an edge region of the frame external to the opening, wherein the edge region completely surrounds the opening.

[0022] According to a favorable embodiment, the inflow and/or outflow areas of the first group of flow ducts and/or the second group of flow ducts can each feature at least one spacer for spacing the adjacent support plates, wherein the spacer extends away from at least one of the support plates in or opposite the stack direction and rests against an adjacent support plate.

[0023] This can favorably keep the inlet air flow and outflow areas open for inlet air and/or exhaust gas, in particular even if relatively higher pressures prevail in the adjacent flow ducts.

[0024] The height of the flow ducts depends on the dimensions of the connecting portions and/or on the dimensions of the spacers, which determine the distance between the support plates disposed one above the other. The duct heights of the flow ducts can therefore be determined via the dimensions, in particular in the stack direction, of the spacers.

[0025] In embodiments, a first spacer can be present on the first sides of the support plates within a single bead present on the first side of one of the support plates and extend in particular against a bead depth of the single bead. The arrangement of the first spacer within the single bead in this connection is particularly space-saving, so that as a result a cross-sectional area of the opening of the support plates and thus the moisture transfer surface covered by the membrane can be maximized. The first spacer can in particular be produced together with the single bead in a reshaping process, in particular a deep drawing process.

[0026] In embodiments, the first spacer can rest against a second spacer of an adjacent support plate, wherein the second spacer extends in particular against a bead depth of a double bead present on the first side of the adjacent support plate. The second spacer can in particular be present within the double bead. The arrangement of the second spacer within the double bead is particularly space-saving in this connection, so that as a result a cross-sectional area of the opening of the support plates and thus the moisture transfer surface covered by the membrane can be maximized. The second spacer can in particular be produced together with the double bead in a reshaping process, in particular a deep drawing process.

[0027] In this context, "within" refers to an arrangement of the respective first and/or second spacer transverse to the stack direction, in which the respective spacer is flanked on two sides by bead walls of the single or double bead. "Within", however, explicitly does not require an overlap in stack direction.

[0028] According to a further embodiment, a third spacer can be present on the second sides of the support plates on one of the support plates, said spacer extending in particular against a bead depth of a single bead present on the second side of one of the support plates, wherein the third spacer is present in particular in an area lying outside the single bead.

[0029] In this connection, the third spacer can rest on a fourth spacer of an adjacent support plate, which extends in particular against a bead depth of a double bead present on the second side of the adjacent support plate. The fourth spacer can in particular be present in an area located outside the double bead.

[0030] In this context, "outside" refers to an arrangement of the respective third and/or fourth spacer transverse to the stack direction, in which the respective spacer is flanked only on one side by a bead wall of the single or double bead. In particular, the arrangement transverse to the stack direction can be provided in such a way that the third and/or fourth spacer is disposed radially on the outside with respect to the single or double bead.

[0031] The inflow and/or outflow areas of the first group of flow ducts on the first sides of the support plates are in embodiments formed by the first and second spacers. Alternatively or additionally, the inflow and/or outflow areas of the second group of flow ducts on the second sides of the support plates are in embodiments formed by the third and fourth spacers.

[0032] The first group of flow ducts can be humid gas ducts or exhaust gas ducts, upon which the second group of flow ducts can be dry gas ducts or supply air ducts, or vice versa.

[0033] In embodiments, the at least one spacer can be designed as a local elevation, in particular as a deep-drawn dome, wherein a plurality of spaced spacers are preferably present in the area of the inflow and/or outflow areas of the first group of flow ducts and/or the second group of flow ducts. In this connection, the spacer can in particular be spaced along an extension of a respective edge of the support plate on the first and/or second side, in particular at regular intervals. Thanks to a plurality of spacers, the support effect can be improved with respect to adjacent support plates, so that the flow cross sections provided by the inflow and/or outflow areas are not inadmissibly narrowed either in operation or during assembly.

[0034] According to a yet further embodiment, a bead depth and/or a bead width of the single bead can be less than a bead depth and/or a bead width of the double bead. In this connection, a hollow space, which is at least partially filled by a sealant, can be formed between the single bead and the double bead. In this connection, the double bead in particular provides a receiving area for a sealant, which can be metered into the receiving area in a fluid state during production. In this connection, thanks to the different bead depths and/or bead widths upon which the single beads and double beads differ, the thickness of a gasket formed by the sealant can be adjusted.

[0035] The double bead features in particular at least two spaced bead strands, extending in particular parallel, between which the single bead is accommodated. In this connection, the bead strands of the double bead delimit the area for receiving the sealant in a plane extending transversely to the stack direction, in particular in a support plate ground plane.

[0036] The term "support plate ground plane" refers in particular to a plane which is defined by the respective openings provided in the support plates.

[0037] According to an advantageous embodiment, the double bead can feature at least one deaeration area in which a bead depth of at least one of the bead strands is locally reduced. During the production of the stack of plates according to the invention, the deaeration area allows adjacent support plates to be adhesively bonded without air pockets. Through the deaeration area of the double bead, displaced air can escape when the single bead is partially accommodated in the stack direction in the double bead, resulting in maximized adherend areas contacted by the fluid sealant. By "local" is meant a limited extension of the deaeration area along a bead longitudinal direction. In embodiments, it can be expressly provided that a double bead features a plurality of deaeration areas which are spaced apart, in particular in the bead longitudinal direction. Independently of this or in combination with this, deaeration areas can be provided on each of the two spaced bead strands of the double bead.

[0038] In an equally advantageous further embodiment, a bead base of the single bead can be offset, in particular offset in parallel, to a support plate ground plane and/or a bead base of the double bead can be disposed in the support plate ground plane. In particular, it can be provided in this connection that a double bead provided on a first or second side of one of the support plates rests against an adjacent support plate with its bead strands spaced transversely to the stack direction, in particular in a support plate ground plane of the adjacent support plate. In this connection, the bead depth of the double bead or its bead strands determines the height of a flow duct formed between the adjacent support plates.

[0039] According to a yet further embodiment, in areas of the support plates adjacent to the dry gas ducts, the selectively permeable membranes can each be present on a surface of the support plates facing the respective dry gas duct. Since there is usually a relative overpressure in the dry gas ducts with respect to the humid gas ducts, such an arrangement of the selectively permeable membranes prevents leaks, as the membranes are to a certain extent pressed onto their respective contact surface with the support plate due to the relative overpressure in the dry gas ducts. The differential pressure between the inlet air (dry gas ducts) and the exhaust gas (humid gas ducts) in a fuel cell system can usually be in the area of 300 mbar to 600 mbar and can even be as high as 1 bar. [0040] In other words, in areas of the support plates adjacent to the humid gas ducts, the selectively permeable membranes can each be present on a surface of the support plates facing away from the respective humid gas duct.

[0041] Furthermore, in yet another embodiment, at least one receiving groove for a gasket can be present on an exterior side of the stack of plates, in which in particular a gasket is received. In particular, the successive support plates each feature at least one recess open towards the exterior side, by means of which - thanks to the stacking - a receiving groove extending in the stack direction is formed. The gasket can be an axially and/or radially effective gasket designed to seal the stack of plates in a housing.

[0042] By using such a gasket, the stack of plates in the housing of a humidifier can advantageously be disposed in such a way that no cross leakage, i.e. leakage between the two fluid flows, can occur. Thus, an efficient humidification of the inlet air can be achieved by transferring the moisture from the exhaust gas flow.

[0043] In yet further embodiments, a membrane support element and/or a flow mixing element can be present between two adjacent selectively permeable membranes, which covers the entire surface of the opening of the support plates, wherein the membrane support element and/or the flow mixing element is designed, in particular, in the shape of a grid. In particular, the membrane support element and/or the flow mixing element completely covers the moisture transfer surface covered by the membrane.

[0044] The membrane support element and/or the flow mixing element supports the membrane with respect to pressure gradients acting on the moisture transfer surface. The membrane support element and/or the flow mixing element can in particular be designed in one piece so that both functions are combined in one apparatus component. The flow mixing element acts as a flow distributor and can deliberately induce turbulences, which results in the available moisture transfer surface used as efficiently as possible for moisture exchange. The flow mixing element can therefore in particular be a laminar mixer. In addition to plastic material, in particular PPS or PET, metals, in particular stainless steel, can also be used as material for the membrane support element and/or flow mixing element, in particular flow grid. The membrane support element and/or the flow mixing element can in particular feature a cross structure, which features a plurality of struts or ribs crossing under an angle. On the one hand, this maximizes the support area and on the other hand optimizes the flow mixing effect, since a two-dimensional flow influence is achieved. The membrane support element and/or the flow mixing element can be an apparatus component inserted separately into the stack of plates. However, in embodiments, the membrane support element and/or the flow mixing element can also be designed on the support plates, in particular in one piece with a support plate. Corresponding membrane support elements and/or flow mixing element integrated in the support plates can be realized from a flatly provided starting material for the support plates, for example by means of simple punching and bending processes. In particular, each support plate can comprise a membrane support element and/or a flow mixing element.

[0045] A membrane support element and/or a flow mixing element can be present in the dry gas ducts and/or in the wet gas ducts.

[0046] According to a favorable embodiment of the stack of plates, the membrane support element and/or flow mixing element can be placed on the respective first and/or second support plate, in particular bonded to the frame. In doing so, a stable and permanent attachment of the membrane support element and/or flow mixing element to a respective support plate can be achieved.

[0047] According to a further embodiment, the membrane support elements and/or the flow mixing elements allocated to the first support plates can be designed differently from the membrane support elements and/or the flow mixing elements allocated to the second support plates. In particular, the membrane support elements and/or flow mixing elements of the first and second support plates can differ in a height and/or in a thread spacing and/or in an angle of a main extension direction.

[0048] The thread spacing can be variable. The angle of crossing of the threads can typically be 90°, but for example also 60° or feature another value. Such a variation in the embodiment of the grid-like support elements can significantly influence the flow conditions of the corresponding flow duct and thus have a substantial influence on the mass transfer, the moisture transfer from the exhaust gas to the inlet air as well as the associated pressure loss. It can be adapted to suit intended operating conditions.

[0049] In a yet further embodiment, it can be provided that the selectively permeable membranes cover the openings of the support plates over their entire surface in each case, wherein in particular the selectively permeable membranes are each connected, in particular welded or bonded, to a surface of the support plates in an edge region surrounding the openings.

[0050] In embodiments, the support plates can feature or consist of a metallic sheet metal, in particular steel sheet, especially made of a stainless steel. In doing so, it is possible to manufacture a frame that is as thin as possible while still being more stable. As a result, a compact stack of plates can be realized, which at the same time meets the stability requirements during operation of the humidifier. A thickness of the sheet metal can typically be in the range of 0.1 to 0.6 mm, in particular 0.2 to 0.4 mm. [0051] According to another aspect of the present invention, a humidifier for a fuel cell system is proposed, said humidifier featuring a housing having at least one inlet for a first fluid, in particular an exhaust gas of the fuel cell system, an inlet for a second fluid, in particular an inlet air of the fuel cell system, an outlet for the first fluid and an outlet for the second fluid. The humidifier further comprises a stack of plates according to the invention comprising a plurality of selectively permeable membranes, wherein the stack of plates separates a fluid path of the first fluid from a fluid path of the second fluid and enables moisture transfer from the first fluid to the second fluid.

[0052] The humidifier according to the invention represents a special design of a flat membrane humidifier. In a first group of flow ducts flows a first, moist or water-rich fluid, for example exhaust gas from fuel cells, while in another, second group of flow ducts flows a second, dry fluid, for example inlet air for the fuel cells. The second, dry fluid can be moistened by the first fluid via the selectively permeable membranes of the stack of plates.

[0053] The stack of plates is advantageously sealed from the housing in such a way that the fluid path of the first fluid is securely separated from the fluid path of the second fluid and no cross leakage (mixing of the first fluid path with the second fluid path or vice versa) occurs.

[0054] The housing of the humidifier can be made of metal, for example of aluminum. Alternatively, the housing can also be made of plastic material, for example PPS, PPA (polyphtalamide), PA (polyamide).

[0055] The housing can be made in several parts having a removable cover. In this way, the stack of plates can be removed from the housing for maintenance purposes and/or replaced.

DESCRIPTION OF DRAWINGS

[0056] Further advantages will become apparent from the following drawing description. The drawings show an example of an embodiment of the invention. The drawings, the description and the claims contain numerous features in combination. A person of skill in the art will expediently consider the features also individually and combine them to other meaningful combinations.

[0057] Examples are shown in:

Fig. 1 a top view of a stack of plates for a humidifier, in particular for a fuel cell system, according to an example of an embodiment of the invention;

Fig. 2 a side view of the stack of plates of Fig. 1 ;

Fig. 3 detail BE of Fig. 2;

Fig. 4 section BD-BD according to Fig. 1 ;

Fig. 5 detail BF of Fig. 4;

Fig. 6 section BW-BW according to Fig. 1 ;

Fig. 7 detail BX of Fig. 6;

Fig. 8 section BN-BN according to Fig. 1 ;

Fig. 9 detail BP of Fig. 8;

Fig. 10 exploded view of two support plates of the stack of plates of Fig. 1 adjacent to a supply air duct/dry gas duct;

Fig. 11 detail BQ of Fig. 10;

Fig. 12 detail BR of Fig. 10;

Fig. 13 top view of a first support plate of the stack of plates of Fig. 1 from the side of a first flow duct;

Fig. 14a section BG-BG according to Fig. 13;

Fig. 14b detail BJ of Fig. 14a;

Fig. 14c detail BH of Fig. 14a;

Fig. 15 top view of a second support plate of the stack of plates of Fig. 1 from the side of a second flow duct;

Fig. 16a section BK-BK according to Fig. 15;

Fig. 16b detail BL of Fig. 16a;

Fig. 16c detail BM of Fig. 16a;

Fig. 17 a stack of plates according to an example of an embodiment of the invention in design in isometric representation;

Fig. 18 a stack of plates according to an example of an embodiment of the invention in isometric representation; and

Fig. 19 a humidifier, in particular for a fuel cell system, according to an example of an embodiment of the invention in isometric representation.

DESCRIPTION OF EMBODIMENTS

[0058] Identical or similar components in the figures have the same reference numerals. The figures only show examples and are not to be understood in a restrictive way.

[0059] The stack of plates 400 comprises a plurality of first and second support plates 100, 200 alternately following one another in a stack direction 500 (cf. Fig. 2), each plate featuring a peripheral frame 120, 220 surrounding an opening 230. First and second groups of flow ducts 410, 420 (cf. Fig. 5) are designed in the stack of plates 400, each of which is separated by selectively permeable membranes 110, 120 (cf. Fig. 5), in particular to water-vapor permeable membranes 110, 210. Each of the selectively permeable membranes 110, 120 can include, for example, a PFSA (perfluorosulfonic acid) membrane, and is airtight but permeable to moisture. Three each of the first and second support plates 100, 200 alternately following one another form two of the flow ducts 410, 420. A second support plate 200 which terminates the stack of plates 400 in the stack direction is shown in the representation of Fig. 1. In practice, a stack of plates 400 can comprise up to 120 support plates 100,200, wherein a significantly smaller quantity of support plates 100,200 is shown in the figures for the sake of clarity.

[0060] The stack of plates 400 is designed and intended to fluidically guide two fluids separately in the first and second groups of flow ducts 410,420. In particular, the first fluid 600 can be a (relatively moist) exhaust gas from a fuel cell stack and the second fluid 602 can be an inlet air (relatively dry) for a fuel cell stack. The stack of plates 400 allows moisture to be transferred from the first fluid 600 to the second fluid, and possibly vice versa. In this connection, the exchange of moisture occurs at the selectively permeable membrane, which in particular is impermeable to liquids and gases but allows a transfer of water molecules. The first and/or second fluid 600,602 is in particular air having different degrees of moisture.

[0061] The support plates 100,200 each comprise a frame 120,220 which surrounds the opening 130,230.

[0062] The selectively permeable membranes 1 10, 210 are each connected in a fluid-tight manner, for example bonded or welded, to the support plates 100, 200 in an area surrounding the opening 130, 230 in the support plates 100, 200. In this connection, the respective selectively permeable membrane 110, 210 rests on the frame 120, 220 in the area of a contact surface 128, 288 (see, among others, Fig. 5 and Fig. 7).

[0063] The support plates 100,200 that form the stack of plates 400 each have a first side 124,224 which is present on a longitudinal side. Furthermore, the support plates 100,200 feature each a second side 122,222 which is present on a transverse side. Inflow and/or outflow areas of the first group of flow ducts 410 are designed on their opposing first sides 124,224 transverse to the stack direction between each two successive first 100 and second support plates 200 in the stack direction 500. The two first 100 and second support plates 200 successive in the stack direction 500 have their second sides 122,222 opposing transversely to the stack direction connected to each other in a fluid- tight manner by means of a connecting portion 150,250. Therefore, the connecting portion 150,250 provides a lateral limit to the flow duct of the first group of flow ducts 410.

[0064] The basic shape of the support plates 100,200 is rectangular having a longitudinal side 124 and a transverse side 122. In embodiments not shown in the figures, however, the basic shape of the support plates can also be any polygon.

[0065] On the other hand, two successive second 200 and first support plates 100 in the stack direction 500 are in each case connected to one another in a fluid-tight manner by a connecting portion

150,250 on at least two second sides 122,222 opposing one another transversely to the stack direction in each case, while an inflow and/or outflow area of the second group of flow ducts 420 is designed between the support plates 100, 200 on at least two of its first sides 124,224 opposing one another transversely to the stack direction in each case.

[0066] Seen in the stack direction 500, this results in an alternating sequence of flow ducts of the first group 410 and flow ducts of the second group 420, so that the stack of plates 400 can be flowed through by the first and second fluids 600,602 in cross flow.

[0067] The connecting portions 150,250 forming the lateral flow duct gasket are each formed by a double bead 152,252 on one of the support plates 100,200 and a corresponding single bead 160,260 on an immediately adjacent support plate 100,200, wherein the single bead 160,260 is accommodated at least section-wise in the double bead 152,252 (see, among others, Fig. 5 and Fig. 7). [0068] The respective support plates 100,200 comprise a membrane support element 300 designed in one piece with the respective support plate 100,200. In particular, the membrane support element 300 can be designed in a grid-like manner and project in the stack direction 500 from a support plate ground plane 101 ,201 of the respective support plate 100,200. In particular, the membrane support element 300 can be produced by means of punching and bending a support plate material. The membrane support element 300 comprises a plurality of spaced apart webs extending under an angle to the first and second sides 124,224,122,222. When assembled, the angularly disposed webs of the membrane support members 300 of adjacent support plates 100,200 intersect.

[0069] In Fig. 5, detail BF of Fig. 4 illustrating the section BD-BD according to Fig.1 is shown. Here, in particular, the inflow and/or outflow portions of the first group of flow ducts 410 provided on the first side 124,224 as well as the connecting portions 150 provided on the first side 124,224 are clearly visible. On the first side 124,224, the first support plates 100 comprise a double bead 152 and the second support plates 200 a single bead 260. In this connection, the single bead 260 is at least partially accommodated in the double bead 152 to form the connecting portion 150. A hollow space 1522 is formed between the double bead 152 and the single bead 260, which is filled with a sealant, exemplary illustrated for one of the connecting portions 150 present on the first side 124,224 by the black coloring. More precisely, the hollow space 1522 is delimited by the bead base 1524 of the double bead 152, the bead base 2602 of the single bead 260, the two in particular parallel bead strands 154 of the double bead 152, and the bead flanks of the single bead 260.

[0070] Initially, the sealant can be metered into the double bead 152 in a flowable state during fabrication of the stack of plates 400, wherein the adjacent plate is then positioned in such a way that the single bead 260 is accommodated within the double bead 152. The height of the hollow space 1522 in the stack direction is defined by the difference between the bead depth 1521 of the double bead 152 and the bead depth 2601 of the single bead 260.

[0071] The stack of plates 400 is mechanically held together on the first side 124,224 via the connecting portions 150; further, the connecting portions 150 seal the flow ducts 420 of the second group on the first side 124,224. The flow ducts 410 of the first group feature inflow and/or outflow areas on the first side 124,224. In this connection, the inflow and/or outflow areas are kept open using spacers 240,241 of the first and second support plates 100,200. Specifically, a first spacer 240 is designed on the second support plates 200 and extends against a bead depth 2601 of the single bead 260. In this connection, the first spacer 240 is disposed within the single bead 260. A second spacer 241 is designed on the first support plates 100, extending against a bead depth 1521 of the double bead 152 and disposed within the double bead 152. When assembled, the first spacer 240 rests against the second spacer 241 so that the flow duct of the first group 410 is kept open on the first side 124,224 for outflow or outflow of first fluid 600.

[0072] The second fluid 602 flows in the ducts of the second group of flow ducts 420, wherein the through-flow direction extends into the image plane in the representation.

[0073] A duct width of the flow ducts 420 of the second group (in particular dry gas ducts) is defined in this connection by means of a bead depth 1521 of the double bead 152. The bead depth of the double bead 152 can be between 0.8 and 2.5 mm, in particular between 1.0 and 1.8 mm.

[0074] The flow ducts 410 of the first group can in particular be humid gas ducts 410. The flow ducts 420 of the second group can in particular be dry gas ducts 420.

[0075] A selectively permeable membrane 110,210 is attached to each support plate 100, 200. In this connection, a selectively permeable membrane 110 of the first support plates 100 is connected, in particular bonded or welded, to the support plate 100 in a contact surface 128 in an edge region surrounding the opening 130. The first support plate 100 features a surface 125 facing the humid gas duct 410 and a surface 126 facing the dry gas duct 420. The selectively permeable membrane 110 is attached to the surface 126 facing the dry gas duct 420.

[0076] A selectively permeable membrane 210 of the second support plates 200 is connected, in particular bonded or welded, to the support plate 200 in a contact surface 228 in an edge region surrounding the opening 230. The second support plate 200 features a surface 225 facing the humid gas duct 410 and a surface 226 facing the dry gas duct 420. The selectively permeable membrane 210 is attached to the surface 226 facing the dry gas duct 420.

[0077] In more general terms, the selectively permeable membranes 110,210 are each disposed on the surfaces of the support plates 100, 200 facing the dry gas ducts 420. This has technical advantages because, during operation of the stack of plates 400 in a humidifier, there is a relative positive pressure in the dry gas ducts with respect to the humid gas ducts 410. Therefore, the arrangement on the surfaces of the support plates 100, 200 facing the dry gas ducts 420 results in improved mechanical strength of the connection of the selectively permeable membranes 1 10,210 to the support plates 100, 200.

[0078] Furthermore, in Fig. 5 the corresponding structure of the membrane support elements 300 of both support plates 100,200 can be identified. The membrane support elements 300, which are designed in particular as a grid, project in or against the stack direction 500 from a support plate ground plane 101 ,201 of the respective support plate 100,200 and rest in contact areas respectively on a membrane support element 300 of an adjacent support plate 100,200. It is by means of this supporting contact that the mechanical strength, in particular against an action of compressive forces in stack direction 500, is significantly improved. More precisely, the membrane support elements 300 project in such a way in or against the stack direction 500 from a support plate ground plane 101 ,201 of the respective support plate 100,200 that the supporting contact occurs in a humid gas duct 410. As already described, due to the relative positive pressure in the dry gas ducts 420 during operation of the stack of plates 400 in a humidifier, a support in the humid gas duct 410 is therefore technically advantageous. In a further embodiment not shown, a further membrane support element can be provided in the dry gas ducts 420, which in particular can be loosely inserted between the support plates 100,200.

[0079] Moreover, the single bead 160 can be identified in the (first or terminal) support plate 100 on the left in the representation - its function is described in detail with reference to Fig. 7.

[0080] In Fig. 7, detail BX of Fig. 6 illustrating the section BW-BW according to Fig.1 is shown. Here, in particular, the inflow and/or outflow portions of the second group of flow ducts 420 provided on the second side 122,222 as well as the connecting portions 250 provided on the second side 122,222 are clearly visible. On the second side 122,222, the first support plates 100 comprise a single bead 160 and the second support plates 200 a double bead 252. In this connection, the single bead 160 is at least partially accommodated in the double bead 252 to form the connecting portion 250. A hollow space 2522 is again formed between the double bead 252 and the single bead 160, said hollow space being filled with a sealant, exemplary illustrated for one of the connecting portions 250 present on the first side 122,222 by the black coloring. More precisely, the hollow space 2522 is delimited by the bead base 2524 of the double bead 252, the bead base 1602 of the single bead 160, the two in particular parallel bead strands 254 of the double bead 252, and the bead flanks of the single bead 160.

[0081] Initially, the sealant can be metered into the double bead 252 in a flowable state during fabrication of the stack of plates 400, wherein the adjacent plate is then positioned in such a way that the single bead 160 is accommodated within the double bead 252. The height of the hollow space in the stack direction is defined by the difference between the bead depth 2521 of the double bead 252 and the bead depth 1601 of the single bead 160.

[0082] The stack of plates 400 is mechanically held together on the second side 122,222 via the connecting portions 250; further, the connecting portions 250 seal the flow ducts 410 of the first group on the second side 122,222. The flow ducts 420 of the second group feature inflow and/or outflow areas on the second side 122,222. In this connection, the inflow and/or outflow areas are kept open using spacers 140,141 of the first and second support plates 100,200. Specifically, a fourth spacer 141 is designed on the second support plates 200 and extends against a bead depth 2521 of the double bead 252. In this connection, the fourth spacer 141 can be disposed outside the double bead 252. A third spacer 140 is designed on the first support plates 100, extending against a bead depth 1602 of the single bead 160 and disposed outside the single bead 160. When assembled, the fourth spacer 141 rests against the third spacer 140 so that the flow duct of the second group 420 is kept open on the second side 122,222 for outflow or outflow of second fluid 602.

[0083] The first fluid 600 flows in the flow ducts 410 of the first group of flow ducts, wherein the through-flow direction extends into the image plane in the representation.

[0084] A duct width of the flow ducts 410 of the first group (in particular humid gas ducts) is defined in this connection by means of a bead depth 2521 of the double bead 252. The bead depth of the double bead 252 can be between 0.5 and 1 .8 mm, in particular between 0.7 and 1 .5 mm.

[0085] In general, it is technically advantageous if the duct width (extension in stack direction) in the dry gas ducts 420 is larger than the duct width in the wet gas ducts 410 due to a lower expected pressure loss.

[0086] In Fig. 9, detail BP of Fig. 8 illustrating the section BN-BN according to Fig.1 is shown. In this connection, the sectional plane of the section BN-BN extends in the stack direction and parallel to the first side 124,224 (longitudinal side) of the stack of plates 400 by means of the first and second support elements 240,241 provided on the first side 124,224. In other words, the sectional plane extends through the bead bases 1524,2602 of the single bead of the 260 second support plate 200 present on the first side 124,224 and the double bead 152 of the first support plate 100. The first and second support elements 240,241 are designed as a dome deep-drawn from a support plate material. Furthermore, the mutually supporting contact of the first and second support elements 240,241 , which hold open the flow duct 410 of the first group, can be clearly identified.

[0087] Fig. 10 illustrates two individual support plates 100,200 delimiting between them a dry gas duct 420 for guiding the second fluid 602. For simplicity, the support plates 100,200 are shown without selectively permeable membranes.

[0088] The double beads 152,252 of the first and second support plates 100,200 each feature two bead strands 154,254, which in particular run parallel to each other and between which a respective bead base 1524,2524 is designed. At least one of the bead strands 154,254 of the double beads 152,252 features at least one deaeration area 1523,2523, respectively, in which a bead depth of at least one of the bead strands 154,254 is locally reduced. During the production of the stack of plates according to the invention, the deaeration area 1523,2523 allows adjacent support plates to be bonded without air pockets, since air displaced through the single beads of an adjacent support plate can escape through the deaeration areas 1523,2523 after the sealant has been metered into the double beads 152,252. In particular, each bead strand 154,254 features at least one deaeration area 1523,2523. Preferably, each bead strand 154,254 features a plurality of deaeration areas 1523,2523 spaced apart in the bead longitudinal direction. Due to the preferred manufacturing method for the support plates 100,200, the deaeration areas 1523,2523 can be created collectively using reshaping in a collective process step with their other apparatus components.

[0089] With respect to the detailed structure of at least one deaeration area 2523 of the double bead 252 of the second support plate 200, reference is made to Fig. 1 1 illustrating the detail BQ of Fig. 10.

[0090] With respect to the detailed structure of at least one deaeration area 1523 of the double bead 152 of the first support plate 100, reference is made to Fig. 12 illustrating the detail BR of Fig. 10. [0091] In Figs. 13 to Figs. 14c, a first support plate 100 is illustrated in a top view, a sectional view BG-BG, and two detailed views BJ and BH of the sectional view. The support plate 100 has a frame 120 that surrounds the opening 130. In the area of the frame 120, a contact surface 128 for the selectively permeable membrane is designed on a surface 126 facing the dry gas duct when assembled, while it is connected to the frame 120. As seen in the drawing, a rear side of the frame 120 forms a surface 125 facing the humid gas duct when assembled. Fig. 14b illustrates the detailed structure of the double bead 152 designed on the first side 124 (longitudinal side). The double bead 152 comprises two parallel bead strands 154 between which a bead base 1524 is disposed. The double bead 152 has a bead depth 1521 that corresponds to the depth of the bead strands 154. The bead base 1524 extends in the same plane as the support plate ground plane 101. Furthermore, the first support plate 100 features a second spacer 241 on the first side 124 (longitudinal side), which extends in the stack direction against the bead depth 1521 of the double bead 152. In this connection, the second spacer 241 is positioned in such a way that, seen transversely to the stack direction, it is disposed within the two bead strands 154 or the two bead strands 154 flank the second spacer 241 , seen transversely to the stack direction. The second spacer 241 is disposed offset from the support plate ground plane 101 in the stack direction. In this case, the second spacer 241 can in particular project from the support plate ground plane 101 in the range of 0.5 to 1.5 mm, in particular 0.7 to 1.1 mm. Distributed along a longitudinal extension of the double bead 1521 , a plurality of second spacers 241 are present.

[0092] Fig. 14c illustrates a third spacer 140 that is present on the second side 122 (transverse side) of the first support plate 100. The third spacer 140 is disposed outside a single bead 160 present on the second side 122, as seen transversely to the stack direction. The third spacer 140 is disposed offset from the support plate ground plane 101 in the stack direction, however in a direction opposed to the second spacer 241. In this case, the third spacer 140 can in particular project from the support plate ground plane 101 in the range of 0.4 to 1.1 mm, in particular 0.6 to 0.8 mm. Distributed along a longitudinal extension of the second side 122 (transverse side), a plurality of third spacers 140 are present.

[0093] In Figs. 15 to Figs. 16c, a second support plate 200 is illustrated in a top view, a sectional view BK-BK, and two detailed views BL and BM of the sectional view. The support plate 200 has a frame 220 that surrounds the opening 230. In the area of the frame 220, a contact surface 228 for the selectively permeable membrane is designed on a surface 226 facing the dry gas duct while assembled, in which it is connected to the frame 220. The contact surface 228 and the surface 226 facing the dry gas duct are disposed on a rear side of the frame 220 as seen in the drawing. As seen in the drawing. the side of the frame 220 facing forward forms a surface 225 facing the humid gas duct when assembled. Fig. 16b illustrates the detailed structure of the single bead 260 designed on the first side 224 (longitudinal side). The single bead 260 comprises a bead strand forming a bead base 2602. The single bead 260 has a bead depth 2601 that corresponds to an extension of the bead strand in the stack direction. The bead base 2602 extends in the stack direction offset from the support plate ground plane 201. Furthermore, the second support plate 200 features a first spacer 240 on the first side 224 (longitudinal side), which extends in the stack direction against the bead depth 2601 of the single bead 260. In this connection, the first spacer 240 is positioned in such a way that, seen transversely to the stack direction, it is disposed within the single bead 260 or flanked by bead walls of the single bead 260. Distributed along a longitudinal extension of the single bead 260, a plurality of fist spacers 240 are present.

[0094] Fig. 16c illustrates a fourth spacer 141 that is present on the second side 222 (transverse side) of the second support plate 200. The fourth spacer 141 is disposed outside a double bead 252 present on the second side 222, as seen transversely to the stack direction. The fourth spacer 141 is disposed offset from the support plate ground plane 201 in the stack direction, however in a direction opposed to the first spacer 240. In this case, the fourth spacer 141 can in particular project from the support plate ground plane 201 in the range of 0.4 to 1.1 mm, in particular 0.6 to 0.8 mm. Distributed along a longitudinal extension of the second side 222 (transverse side), a plurality of fourth spacers 141 are present.

[0095] The first and second support plates 100, 200 respectively feature on their first sides 124, 224 (longitudinal sides) a recess 170, 270 open towards the exterior side. By stacking a plurality of support plates in the stack direction, a receiving groove 432 extending in the stack direction 500 for a gasket 430 (see Fig. 17) is formed.

[0096] Fig. 17 illustrates a stack of plates 400 according to an embodiment of the invention in design in isometric view, while Fig. 18 illustrates a stack of plates 400 in a finished state, which means having end plates 11. The end plates 11 delimit the stack of plates 400 on both sides in the stack direction.

[0097] In the stack of plates 400, first and second groups of flow ducts 410, 420, respectively, are designed to be flowed through transversely to one another, which are separated by the selectively permeable membranes 110, 210, in particular water-vapor permeable membranes 110, 210, of the support plates 100, 200. In doing so, two of the flow ducts 410, 420 designed to be flowed through transversely to one another are formed by three, respectively, of the alternately successive first and second support plates 100, 200.

[0098] In doing so, the first flow ducts 410 for the second fluid flow 602, for example the inlet air of the fuel cell, extend horizontally through the stack of plates 400 in the illustrated embodiment, while the second flow ducts 420 for the first fluid flow 600, for example the exhaust gas of the fuel cell, extend vertically from top to bottom through the stack of plates 400.

[0099] On an exterior side of the stack of plates 400, a receiving groove 432 is disposed for an axial or radial gasket 430, which is formed through recesses or cuts 170, 270 open to the exterior side in the frames 120, 220 of the successive support plates 100, 200. The gasket 430 can be used to seal the inlet area of the first fluid flow 600, i.e. the exhaust gas of the fuel cell, when the stack of plates 400 is installed in the housing 1002 of a humidifier 1000, as shown in Fig. 19. Bypass flow that would otherwise occur in the housing 1002 can thus be effectively prevented.

[0100] Fig. 19 shows a humidifier 1000, in particular for a fuel cell system, according to an example of an embodiment of the invention in isometric representation.

[0101] The humidifier 1000 features a housing 1002 featuring at least one inlet 1004 for a first fluid 600, in particular an exhaust gas of the fuel cell system, an inlet 1008 for a second fluid 602, in particular an inlet air of the fuel cell system, an outlet 1006 for the first fluid 600 and an outlet 1010 for the second fluid 602. A stack of plates 400 is disposed in the housing 1002, as shown in Fig. 18, in which a plurality of first and second support plates 100, 200 alternately following one another in a stack direction 500 are disposed.

[0102] Three of each of the alternating successive first and second support plates 100, 200 form a first and a second group of flow ducts 410, 420 designed to be flowed through transversely of each other. The first group of flow ducts 410 is disposed between the inlet 1008 and the outlet 1010 for the second fluid 602, and the second group of flow ducts 420 is disposed between the inlet 1004 and the outlet 1006 for the first fluid 600.

REFERENCE SIGNS LIST

100 first support plate

101 support plate ground plane

110 selectively permeable membrane

120 first frame

122 second side / transverse side

124 first side / longitudinal side

125 surface of the first support plate pointing towards the humid gas duct

126 surface of the first support plate pointing towards the dry gas duct

128 contact surface

130 opening

140 third spacer

141 fourth spacer

150 connecting portion

152 double bead

1521 bead depth of the double bead

1522 hollow space

1523 deaeration area

1524 bead base

154 bead strand

160 single bead

1601 bead depth of the single bead

1602 bead base

170 open recess

200 second support plate

201 support plate ground plane

210 selectively permeable membrane

220 second frame

222 second side / transverse side

224 first side / longitudinal side

225 surface of the second support plate pointing towards the humid gas duct

226 surface of the second support plate pointing towards the dry gas duct

228 contact surface

230 opening

240 first spacer

241 second spacer

250 connecting portion

252 double bead

2521 bead depth of the double bead

2522 hollow space

2523 deaeration area

2524 bead base

254 bead strand

260 single bead

2601 bead depth of the single bead

2602 bead base

270 open recess

300 membrane support element

400 stack of plates

410 first flow duct I humid gas duct

420 second flow duct / dry gas duct

430 gasket

432 receiving groove

500 stack direction

600 first fluid (exhaust gas)

602 second fluid (inlet air)

1000 humidifier

1002 housing

1004 inlet first fluid

1006 outlet first fluid

1008 inlet second fluid

1010 outlet second fluid

Claims

1 . Stack of plates (400) for a humidifier (1000), in particular for a fuel cell system, having a plurality of first and second support plates (100, 200) alternately following one another in a stack direction (500), each support plate featuring a peripheral frame (120, 220) surrounding an opening (130, 230), wherein first and second groups of flow ducts (410, 420) are designed in the stack of plates (400), each of which is separated by selectively permeable membranes (110, 210), in particular watervapor permeable membranes (110, 210), wherein three each of the first and second support plates (100, 200) alternately following one another form two of the flow ducts (410, 420), wherein two successive first (100) and second support plates (200) in the stack direction (500) are in each case connected to one another in a fluid-tight manner by a connecting portion (150,250) on at least two first sides (124,224) opposing one another transversely to the stack direction in each case, while an inflow and/or outflow area of the first group of flow ducts (410) is designed between the support plates (100, 200) on at least two of its second sides (122,222) opposing one another transversely to the stack direction in each case, wherein two successive second (200) and first support plates (100) in the stack direction (500) are in each case connected to one another in a fluid-tight manner by a connecting portion (150,250) on at least two second sides (122,222) opposing one another transversely to the stack direction in each case, while an inflow and/or outflow area of the second group of flow ducts (420) is designed between the support plates (100, 200) on at least two of its first sides (124,224) opposing one another transversely to the stack direction in each case, wherein the connecting portions (150,250) are each formed by a double bead (152,252) on one of the support plates (100,200) and a corresponding single bead (160,260) on the other support plate

(100.200), and wherein the single bead (160,260) is accommodated at least section-wise in the double bead (152,252).

2. Stack of plates (400) according to claim 1 , wherein the inflow and/or outflow areas of the first group of flow ducts (410) and/or the second group of flow ducts (420) each feature at least one spacer (140,141 ,240,241 ) for spacing the adjacent support plates (100,200), and wherein the spacer (140,141 ,240,241 ) extends away from at least one of the support plates

(100.200) in or opposite the stack direction (500) and rests against an adjacent support plate (100,200).

3. Stack of plates (400) according to claim 2, wherein a first spacer (240) is present at the first sides (124,224) of the support plates (100,200) within a single bead (160,260) present at the first side (124,224) of one of the support plates (100,200) and extends in particular against a bead depth (1601 ,2601) of the single bead (160,260).

4. Stack of plates (400) according to claim 3, wherein the first spacer (240) rests against a second spacer (241) of an adjacent support plate (100,200), wherein the second spacer (241 ) extends in particular against a bead depth (1521 ,2521) of a double bead (152,252) present on the first side (124,224) of the adjacent support plate (100,200), and wherein in particular the second spacer (241) is present within the double bead (152,252).

5. Stack of plates (400) according to one of the claims 2 to 4, wherein a third spacer (140) is present on the second sides (122, 222) of the support plates (100, 200) on one of the support plates (100, 200), said third spacer (140) extending in particular against a bead depth of a single bead (160, 260) present on the second side (122, 222) of one of the support plates (100, 200), and wherein the third spacer (140) is present in particular in an area lying outside the single bead (160, 260).

6. Stack of plates (400) according to claim 5, wherein the third spacer (140) rests against a fourth spacer (141) of an adjacent support plate (100,200), wherein the fourth spacer (141 ) extends in particular against a bead depth of a double bead

(152.252) present on the second side (122,222) of the adjacent support plate (100,200), and wherein the fourth spacer (141) is present in particular in an area lying outside the double bead

(152.252).

7. Stack of plates (400) according to one of the claims 3 to 6, wherein the inflow and outflow areas of the first group of flow ducts (410) are formed on the first sides of the support plates (100,200) by the first and second spacers ((240,241 ), and/or wherein the inflow and outflow areas of the second group of flow ducts (420) are formed on the second sides of the support plates (100,200) by the third and fourth spacers (140,141).

8. Stack of plates (400) according to one of the claims 2 to 7, wherein the at least one spacer (140,141 ,240,241 ) is designed as a local elevation, in particular as a deep-drawn dome, and wherein a plurality of spaced spacers (140,141 ,240,241 ) are present in the area of the inflow and/or outflow areas of the first group of flow ducts (410) and/or the second group of flow ducts (420).

9. Stack of plates (400) according to one of the preceding claims, wherein a bead depth and/or bead width of the single bead (160,260) is less than a bead depth and/or bead width of the double bead (152,252), and wherein a hollow space (1522,2522) is formed between the single bead (160,260) and the double bead (152,252), said hollow space being at least partially filled by a sealant.

10. Stack of plates (400) according to one of the preceding claims, wherein the double bead (152,252) features at least two spaced bead strands (154, 254), extending in particular parallel, between which the single bead (160,260) is accommodated.

11. Stack of plates (400) according to claim 10, wherein the bead strands (154,254) of the double bead (152,252) feature at least one deaeration area (1523,2523) in which a bead depth of at least one of the bead strands (154,254) is locally reduced.

12. Stack of plates (400) according to one of the preceding claims, wherein a bead base (1602,2602) of the single bead (160,260) is offset, in particular offset in parallel, to a support plate ground plane (101 ,201), and/or wherein a bead base (1524,2524) of the double bead (152,252) is disposed in the support plate ground plane (101 ,201).

13. Stack of plates (400) according to one of the preceding claims, wherein the first group of flow ducts (410) comprises humid gas ducts (410) and the second group of flow ducts (420) comprises dry gas ducts (420).

14. Stack of plates (400) according to claim 13, wherein in areas of the support plates (100,200) adjacent to the dry gas ducts (420), the selectively permeable membranes (110,210) are each present on a surface (126,226) of the support plates (100,200) facing the respective dry gas duct (420), and wherein in areas of the support plates (100,200) adjacent to the humid gas ducts (410), the selectively permeable membranes (110,210) are each present on a surface (126,226) of the support plates (100,200) facing away from the respective humid gas duct (410).

15. Stack of plates (400) according to one of the preceding claims, wherein at least one receiving groove (432) for a gasket (430) is present on an exterior side of the stack of plates (400), and wherein in particular the successive support plates (100, 200) respectively feature a recess (170, 270) open to the exterior side, through which a receiving groove (432) extending in the stack direction (500) is formed.

16. Stack of plates (400) according to one of the preceding claims, wherein a membrane support element (300) is present between two adjacent selectively permeable membranes (110,210), which covers the entire surface of the opening (130,230) of the support plates (100,200), and wherein the membrane support element (300) is designed, in particular, in the shape of a grid.

17. Stack of plates (400) according to claim 16, wherein the membrane support element (300) is placed on a respective first and/or second support plate (100,200), in particular bonded to the frame (120,220).

18. Stack of plates (400) according to claim 16, wherein the membrane support element (300) is designed in one piece with the support plates (100,200), and wherein in particular each support plate (100,200) comprises a membrane support element (300).

19. Stack of plates (400) according to claim 18, wherein the membrane support elements (300) allocated to the first support plates (100) are designed differently from the membrane support elements (300) allocated to the second support plates (200), and wherein in particular the membrane support elements (300) differ in a height and/or in a thread spacing and/or in an angle of a main extension direction.

20. Stack of plates (400) according to one of the preceding claims, wherein the selectively permeable membranes (110, 210) cover the openings (130, 230) of the support plates over their entire surface in each case, and wherein in particular the selectively permeable membranes (110, 210) are each connected, in particular welded or bonded, to a surface of the support plates (100,200) in an edge region surrounding the openings (130, 230).

21. Stack of plates (400) according to one of the preceding claims, wherein the support plates (100,200) feature or consist of a metallic sheet metal material, in particular steel sheet, and/or wherein the first and second sides (122,222,124,224) of the support plates (100,200) are respectively present in an edge region of the frame (120,220) lying outside the opening (130,230).

22. Humidifier (1000) for a fuel cell system, having: a housing (1002) which features at least one inlet (1004) for a first fluid (600), in particular an exhaust gas of the fuel cell system, an inlet (1008) for a second fluid (602), in particular of an inlet air of the fuel cell system, an outlet (1006) for the first fluid (600) and an outlet (1010) for the second fluid (602); and a stack of plates comprising a plurality of selectively permeable membranes (110, 210), which separates a fluid path of the first fluid (600) from a fluid path of the second fluid (602) and enables a moisture transfer from the first fluid (600) to the second fluid (602), wherein the stack of plates is a stack of plates (400) according to one of the claims 1 to 21.