Fuel cell humidifier, air supply device and fuel cell system

Abstract

The invention relates to a fuel cell humidifier (10) for an air supply device for a fuel cell system, an air supply device and a fuel cell system.

Description

The invention relates to a fuel cell humidifier according to the preamble of claim 1.A fuel cell humidifier is an essential component of a fuel cell. A fuel cell converts the chemical energy of a fuel, typically hydrogen, and oxygen into electrical energy. This process occurs at the anode and cathode which are separated by an electrolytic membrane. At the anode, the oxidation of the fuel occurs, releasing electrons that flow through an external circuit and generate electric current. At the cathode, there is reduction of oxygen which reacts with the electrons from the circuit and hydrogen ions to form water.The fuel cell humidifier plays a decisive role in this process. Its primary function is to keep the membrane moist, since a dry membrane loses its ionic conductivity, which impairs the efficiency of the fuel cell. The fuel cell humidifier enables humidification of the supply air supplied to the fuel cell by extracting moisture from the exhaust air discharged from the fuel cell.US 2003 / 228507 A1 describes a fuel cell humidifier with a first and second guide plate and an intermediate layer. The first guide plate has a plurality of first grooves and various openings for the entry of dry supply air, which flows through the grooves and subsequently enters the fuel cell. The second guide plate, with second grooves and further openings, guides the exhaust air out of the fuel cell. The grooves in both guide plates are orthogonal to each other. The intermediate layer between the two guide plates consists of a water-permeable layer and two water-absorbing layers. The water absorbing layers are hydrophilic and absorb water content from the air streams. The water-permeable layer prevents the air in the grooves of both guide plates from mixing, but allows moisture to be transferred to the supply air from the exhaust air. The water-absorbing layers are adhered to the water-permeable layer to form the intermediate layer. The water-permeable layer has special glue sites which allow attachment to the guide plates without impairing the air flow in the grooves.The object of the present invention is to improve the adhesive connection. The adhesive connection is to be implemented more stably. Airtightness is to be improved.At least one of these objects is achieved by a fuel cell humidifier having the features according to claim 1. As a result, the sealing within the air conduction paths and between the air conduction paths of the fuel cell humidifier can be improved. The sealing of the fuel cell humidifier may require fewer insert seals. The fuel cell humidifier may be operated more efficiently and have a longer durability. The fuel cell humidifier can be made more robust and cost-effective. Expensive grooves in the components can be dispensed with.The fuel cell system includes a fuel cell. The fuel cell may include a membrane electrode assembly including an anode, cathode, and a membrane. The membrane may be a proton exchange membrane (PEM. The membrane may be a polymer membrane.The supply air in the first air guide path can have a higher pressure than the exhaust air in the second air guide path. The supply air can be compressed.The exhaust air can be partially or completely removed from the fuel cell system.A seal toward the outside means an airtight seal of the respective air conduction path with respect to the surroundings of the fuel cell humidifier.The exchange membrane can be moisture-permeable, i.e. water vapor-permeable and impermeable with respect to air, preferably with respect to oxygen molecules and nitrogen molecules. The exchange membrane may be a hollow fiber membrane consisting of a bundle of very small tubular fibers. The exchange membrane may comprise a flat membrane, preferably a microporous membrane with small pores for transferring water vapor molecules. The replacement membrane may be made of polypropylene or PTFE (polytetrafluoroethylene).The exchange membrane can bear directly against the first and / or second air guide element. The first and / or second air guide element can have support elements for supporting the exchange membrane abutting thereon. The support elements can delimit the air ducts laterally and preferably comprise support ribs.The first intermediate space can be sealed off from the outside exclusively by the adhesive layer between the first air guide element and the exchange membrane. The second intermediate space can be sealed off from the outside exclusively by the adhesive layer between the second air guide element and the exchange membrane. An additional insert sealing element between the first air guide element and the replacement membrane and / or a groove in the first air guide element for an insert sealing element can be omitted. An additional insert sealing element between the second air guide element and the replacement membrane and / or a groove in the second air guide element for an insert sealing element can be omitted.The first and second air guide elements can be shaped to match at least 90% with respect to a base surface. The first and second air guide elements can be identical, preferably arranged rotated through 180° with respect to one another in the exchange device.In a preferred embodiment of the invention, it is advantageous if the second air guide element has at least one support structure in a region on which the first air guide element is at least partially supported and / or the first air guide element has at least one support structure in a region on which the second air guide element is at least partially supported. As a result, the first and second air guide elements with the exchange membrane lying therebetween can be reliably glued to one another by pressing, in that the adhesive surface is supported. The thickness of the adhesive layer can be reduced and thus the contact surface of the adhesive against the air pressure in the corresponding air guide path.In an advantageous embodiment of the invention, it is provided that the replacement device has, in addition to the replacement assembly, at least one such further replacement assembly stacked therewith. The replacement assemblies can be braced with one another via fastening elements, for example screws or rivets. As a result, the adhesive surface can be braced under pressure. Detachment of the adhesive connection during operation of the fuel cell humidifier can be prevented.Preferably, the modulus of elasticity of the adhesive is less than that of the fastening elements in order to absorb changes in length, in particular due to changing air pressure in the air guide paths via the fastening elements.The exchange assembly and the further exchange assembly can be connected in parallel with respect to an air duct of the first and / or second air duct path.A preferred embodiment of the invention is advantageous in which a moisture-permeable further exchange membrane adjacent to the second air-guiding element is arranged between the exchange assembly and the further exchange assembly. The exchange membrane and the further exchange membrane can be identical.In a preferred embodiment of the invention, it is advantageous if the first air guide element and the further exchange membrane each have flat adhesive surfaces on a partial surface, which are bonded to one another in a sealing manner towards the outside. The adhesive surfaces with the corresponding adhesive layer can each completely span and seal a further intermediate space between the further exchange membrane and the first air guide element towards the outside.The first air guide element can be arranged between the exchange membrane and the further exchange membrane.In an advantageous embodiment of the invention, it is provided that the further replacement membrane and a further second air guide element of the further replacement assembly are glued to one another. With this glue interface, the beginning of the stack-up with the further replacement assembly can be formed above the replacement assembly, as explained with respect to the replacement assembly.In a preferred embodiment of the invention, it is advantageous if the further second air guide element and the further replacement membrane each have flat adhesive surfaces on a partial surface, which are adhesively bonded to one another in a sealing manner towards the outside. The further second air guide element can be embodied and glued on a side opposite the further exchange membrane, as explained above with respect to the second air guide element in the direction of the exchange membrane.In a preferred embodiment of the invention, it is advantageous if the first and / or second air guide element has air distribution means which divide the air of the corresponding air guide path into a plurality of air ducts. The air channels may include introduction channels, counter-current channels and / or discharge channels. The counter-flow channels may increase the ratio between a contact surface to the exchange membrane and an air volume of the counter-flow channels.The introduction channels can branch the air from an inlet opening. The discharge ducts can lead the air together in the direction of an outlet opening.Furthermore, within the scope of the invention, for achieving at least one of the objects specified above, an air supply device having the features according to claim 9 is proposed. The air supply device may further comprise an air cooler for cooling the air supplied to the fuel cell humidifier in the second air conduction path, a bypass for bypassing supply air to the fuel cell by bypassing the fuel cell humidifier, and / or a bypass valve controlling the air conduction between the fuel cell humidifier and the bypass.Furthermore, within the scope of the invention, for achieving at least one of the objects specified above, a fuel cell system having the features according to claim 10 is proposed. The membrane electrode unit may comprise an anode, cathode and a membrane, in particular a proton exchange membrane (PEM), for example a polymer membrane.The fuel cell system can have at least one sensor, in particular for measuring pressure or temperature.Further advantages and advantageous embodiments of the invention result from the description of the figures and the figures.DESCRIPTION OF THE FIGURESThe invention will be described in detail below with reference to the drawings. They show in detail: FIG. 1 : A three-dimensional view of a fuel cell humidifier in a specific embodiment of the invention. FIG. 2 : shows a further three-dimensional view of the fuel cell humidifier from FIG. 1. FIG. 3 : An exploded view of the fuel cell humidifier from FIG. 1. FIG. 4 : An exploded view of the fuel cell humidifier from FIG. 1. FIG. 5 : shows a three-dimensional view of the second air guide element of the fuel cell humidifier from FIG. 1. FIG. 6 : shows a detail of a three-dimensional view of the air guide element from FIG. 5. FIG. 7 : shows a three-dimensional view of the second air guide element with adhesive layers of the fuel cell humidifier from FIG. 1. FIG. 8 is an exploded view of a fuel cell humidifier in another specific embodiment of the invention. FIG. 9 : shows a three-dimensional view of the first air guide element of the fuel cell humidifier from FIG. 8. FIG. 10 : shows a three-dimensional view of the second air guide element of the fuel cell humidifier from FIG. 8.FIG. 1 shows a three-dimensional view of a fuel cell humidifier in a specific embodiment of the invention. The fuel cell humidifier 10 for an air supply device for a fuel cell system including a fuel cell includes a first air guide path 12 that guides air as supply air to the fuel cell between a first air inlet 14 and a first air outlet 16.The fuel cell humidifier 10 comprises a first cover 18 and a spaced-apart second cover 20. Between the first and second covers 18, 20 is arranged an exchange device 26.The first cover 18, the replacement device 26 and the second cover 20 are firmly connected and braced to one another by fastening elements 28, here screws.FIG. 2 shows a further three-dimensional view of the fuel cell humidifier from FIG. 1, the fuel cell humidifier 10 is rotated with respect to the view in FIG. 1 and comprises a second air guide path 30 which conducts air moistr than the supply air as exhaust air between a second air inlet 32 and a second air outlet 34, The second air inlet 32 has a third connection piece 36 next to the second connection piece 24 on the second cover 20. The second air outlet 34 has a fourth connection 38.FIG. 3 shows an exploded view of the fuel cell humidifier from FIG. 1 A circumferential first sealing element 40 sealing off from the outside is arranged as an insert seal between the replacement device 26 and the first cover 18. For this purpose, the first sealing element 40 is inserted into a groove 42 in the first cover 18.Opposite the replacement device 26, a circumferential second sealing element 44 sealing off from the outside is arranged as an insert seal between the replacement device 26 and the second cover 20. For this purpose, the second sealing element 44 is inserted in a further groove 46 in the second cover 20.FIG. 4 shows an exploded view of the fuel cell humidifier from FIG. 1 The replacement device 26 arranged between the first cover 18 and the second cover 20 is shown here in a partial exploded view, specifically the part of the replacement device 26 facing the second cover 20. The replacement device 26 has, on the boundary side, a terminating plate 48 which forms a contact surface for the second sealing element 44.The exchange device 26 between the first and second air guide paths 12, 30 comprises at least one exchange assembly 50 for unidirectional exchange of moisture of the exhaust air to the supply air. The first air guide path 12 is spanned between the first air inlet 14, starting with the first connection piece 22 and the first air outlet 16, ending with the second connection piece 24, and the second air guide path 30 is spanned between the second air inlet 32, starting with the third connection piece 36 and the second air outlet 34, ending with the fourth connection piece 38.The exchange assembly 50 comprises a moisture-permeable exchange membrane 52 and a first air guide element 56 which is adjacent to the exchange membrane 52 forming a first intermediate space 54 on the one hand and guides the air of the first air guide path 12 in the first intermediate space 54 along the exchange membrane 52, and a second air guide element 60 which is adjacent to the exchange membrane 52 forming a second intermediate space 58 on the other hand and guides the air of the second air guide path 30 in the second intermediate space 58 along the exchange membrane 52, The second air guide element 60 is adhesively bonded to the end plate 48 in a circumferential manner and in a sealing manner towards the outside via an adhesive layer K 0.The exchange device 26 further includes an adjacent such another exchange assembly 62 stacked thereon. a moisture-permeable another exchange membrane 64 is disposed between the exchange assembly 50 and the another exchange assembly 62 and adjacent to the first air guide member 56.In the replacement assembly 50, the first air guide element 56 and the replacement membrane 52 each have flat adhesive surfaces A 1 on a partial surface, which are bonded to one another by an adhesive layer K 1, wherein the adhesive surfaces A 1 with the adhesive layer K 1 completely span and seal the first intermediate space 54 outwards. Furthermore, in the replacement assembly 50, the second air guide element 60 and the replacement membrane 52 each have flat adhesive surfaces A 2 on a partial surface, which are bonded to one another by an adhesive layer K 2, wherein the adhesive surfaces A 2 with the adhesive layer K 2 completely span and seal the second intermediate space 58 towards the outside.The first air guide element 56 and the further replacement membrane 64 each have flat adhesive surfaces A 3 on a partial surface, which are bonded to one another with an adhesive layer K 3 in a sealing manner towards the outside. In the further replacement assembly 62, the further second air guide element, not shown individually here, and the further replacement membrane 64 each have planar adhesive surfaces on a partial surface, which are bonded to one another by an adhesive layer K 4.FIG. 5 shows a three-dimensional view of the second air guide element of the fuel cell humidifier from FIG. 1 The second air guide element 60 has an inlet opening 66 starting from the second air inlet and an outlet opening 68 towards the second air outlet. From the inlet opening 66 as far as the outlet opening 68, air distribution means 70 extend, which divide the air of the second air conduction path into a plurality of air ducts 72. The air channels 72 are bordered by support elements 73, in particular support ribs, for supporting the exchange membrane directly abutting them.Adjoining the inlet opening 66 are inlet channels 74, which in turn are divided into straight countercurrent channels 76. The countercurrent channels 76 open via merging discharge channels 78 in the outlet opening 68. the countercurrent channels 76 are designed in shape and number such that the ratio between a contact surface to the exchange membrane and an air volume of the countercurrent channels 76 is increased. As a result, the largest possible contact surface between the second air conduction path and the exchange membrane can be implemented.Around the inlet opening 66, a planar adhesive surface A is formed on an upper side 80 and an underside 82. The introduction channels 74 extend between an upper adhesive surface region 84 assigned to the upper adhesive surface and a lower adhesive surface region 86 assigned to the lower adhesive surface.A planar adhesive surface A is also formed around the outlet opening 68 on an upper side 80 and an underside 82. The discharge channels 78 extend between an upper further adhesive surface region 88 assigned to the upper adhesive surface and a lower further adhesive surface region 90 assigned to the lower adhesive surface. The inlet opening 66 and the outlet opening 68, as well as the openings 92 of the first air conduction path, are thus enclosed by a circumferential adhesive surface A on their own and sealed off via the adhesive layer.The upper adhesive surface region 84 and the upper further adhesive surface region 88 each form a support structure 94 in a region on which the first air guide element stacked above it via the intermediate connection of the exchange membrane is at least partially supported. The thickness of the upper adhesive surface region 84 and of the upper further adhesive surface region 88 is preferably 20% to 40% of the total thickness 95 of the second air guide element 60.FIG. 6 shows a detail of a three-dimensional view of the air guide element from FIG. 5 A planar adhesive surface A is formed around the inlet opening 66 on the upper side 80 and the lower side 82, respectively. The introduction channels 74 extend below the upper adhesive surface region 84 as a supporting structure 94.FIG. 7 shows a three-dimensional view of the second air guide element with adhesive layers of the fuel cell humidifier from FIG. 1 The second air guide element 60 has above and below an adhesive layer K 0, K 2, which individually encloses the inlet opening 66, the outlet opening 68 and the openings 92 of the first air guide path.FIG. 8 is an exploded view of a fuel cell humidifier in another specific embodiment of the invention. The structure of the fuel cell humidifier is similar to the fuel cell humidifier of FIG. 4 with differences below. The first air guide element 56 corresponds to the second air guide element 60, but in a configuration rotated by 180°, as shown in FIG. 9. The second air guide member 60 depicted in FIG. 10 is similar to the first air guide member 56 of FIG. 9 except for the rotated orientation.List of reference characters10 Fuel cell humidifier 12 First air guide path 14 First air inlet 16 First air outlet 18 First cover 20 Second cover 22 First connection piece 24 Second connection piece 26 Exchange device 28 Fastening element 30 Second air guide path 32 Second air inlet 34 Second air outlet 36 Third connection piece 38 Fourth connection piece 40 First sealing element 42 Groove 44 Second sealing element 46 Further groove 48 End plate 50 Exchange assembly 52 Exchange membrane 54 First intermediate space 56 First air guide element 58 Second intermediate space 60 Second air guide element 62 Further exchange assembly 64 Further exchange membrane 66 Inlet opening 68 Outlet opening 70 Air distribution means 72 Air ducts 73 Support element 74 Inlet ducts 76 Countercurrent ducts 78 Outlet ducts 80 Upper side 82 Lower side 84 Upper adhesive surface region 86 Lower adhesive surface region 88 Upper further adhesive surface region 90 Lower further adhesive surface region 92 Opening 94 Support structure 95 Total thickness A Adhesive surface A1 Adhesive surface A2 Adhesive surface A3 Adhesive surface K0 Adhesive layer K1 Adhesive layer K2 Adhesive layer K3 Adhesive layer K4 Adhesive layerReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 2003 / 228507 A1

[0004]

Claims

Fuel cell humidifier (10) for an air supply device for a fuel cell system with a fuel cell, comprising a first air guide path (12) guiding air as supply air to the fuel cell system, a second air guide path (30) guiding air moistr than the supply air as exhaust air, at least one exchange device (26) between the first and second air guide paths (12, 30) for transferring moisture of the exhaust air to the supply air, with at least one exchange assembly (50), which has a moisture-permeable exchange membrane (52) and a first air guide element (56) which is on the one hand adjacent to the exchange membrane (52) forming a first intermediate space (54) and guides the air of the first air guide path (12) in the first intermediate space (54) along the exchange membrane (52), and a second air guide element (60) which is on the other hand adjacent to the exchange membrane (52) forming a second intermediate space (58) and guides the air of the second air guide path (30) in the second intermediate space (58) along the exchange membrane (52), wherein the first air guide element (56) and the exchange membrane (52) and the second air guide element (60) and the exchange membrane (52) each have flat adhesive surfaces (A, A1, A2) on a partial surface, via which the exchange membrane (52) with the first and second air guide elements (56, 56, 2) are planar, 60) are each bonded to an adhesive layer (K1, K2) comprising an adhesive, characterized in that the adhesive surfaces (A, A1, A2) with the corresponding adhesive layer (K1, K2) respectively completely span and seal the first and second intermediate spaces (54, 58) towards the outside.Fuel cell humidifier (10) according to claim 1, characterised in that the second air guide element (60) comprises at least one support structure (94) in a region on which the first air guide element (56) is at least partially supported and / or the first air guide element (56) comprises at least one support structure in a region on which the second air guide element (60) is at least partially supported.Fuel cell humidifier (10) according to claim 1 or 2, characterized in that the replacement device (26) comprises, in addition to the replacement assembly (50), at least one such further replacement assembly (62) stacked therewith.Fuel cell humidifier (10) according to claim 3, characterised in that a moisture-permeable further exchange membrane (64) adjacent to the second air guide element (60) is arranged between the exchange assembly (50) and the further exchange assembly (62).Fuel cell humidifier (10) according to claim 4, characterised in that the first air guide element (56) and the further replacement membrane (64) each have flat adhesive surfaces (A3) on a partial surface, which are sealingly bonded to one another towards the outside.Fuel cell humidifier (10) according to claim 4 or 5, characterised in that the further replacement membrane (64) and a further second air guiding element of the further replacement assembly (62) are glued to one another.Fuel cell humidifier (10) according to claim 6, characterised in that the further second air guide element and the further replacement membrane (64) each have flat adhesive surfaces on a partial surface, which are glued to each other in a sealing manner towards the outside.Fuel cell humidifier (10) according to one of the preceding claims, characterized in that the first and / or second air guiding element (56, 60) comprises air distribution means (70), which divide the air of the corresponding air guiding path (12, 30) into a plurality of air channels (72).An air supply device for a fuel cell system, comprising a fuel cell humidifier (10) according to any one of the preceding claims.A fuel cell system comprising at least one fuel cell having a membrane electrode unit and an air supply device according to claim 9 for supplying supply air to the fuel cell.

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