Humidification device

Abstract

Humidification device (10) for humidifying dry air (22), in particular for fuel cells, comprising a plurality of repeating cells (12) connected to form a stack (14), wherein a cell (12) comprises at least: a dry plate (16) with a first flow system (24); a wet plate (18) with a second flow system (30); a moisture-permeable first membrane (20) arranged between the dry plate (16) and the wet plate (18);wherein the first membrane (20) has a support structure (42) extending into the second flow system (30) for supporting the at least first membrane (20), wherein the support structure (42) can be arranged within the wet plate (18) in the region of the second flow system (30) and counteracts a deformation of the at least first membrane (20) in the direction of the adjacent second flow system (30), wherein a second moisture-permeable membrane (21) is arranged between two successive cells (12) and a wet plate (18) of a second cell (12) follows a dry plate (16) of a first cell (12) and vice versa.;

Description

[0001] The following statements relate to a humidification device for humidifying dry air, in particular for fuel cells, comprising a plurality of repeating cells connected to form a stack, which enables efficient and long-lasting operation of fuel cells. Furthermore, the following statements relate to a fuel cell system comprising a fuel cell stack and a humidification device.

[0002] Fuel cells are capable of converting the chemical energy of a process gas into electricity through a reaction with oxygen. Hydrogen is typically used as the process gas to generate energy. Other commonly used process gases include butane, propane, methane, methanol, and other hydrocarbons. Low-temperature fuel cells with an ion-conducting polymer electrolyte that separates an anode from a cathode are particularly well-known. The hydrogen is fed to the anode compartment, the oxygen to the cathode compartment. The hydrogen ions migrate through the electrolyte, and the electrons migrate via an electrical circuit to a consumer outside the cell. Such PEM fuel cells are also called polymer electrolyte fuel cells (PEFCs), proton exchange membrane fuel cells (PEEMFCs), or solid polymer fuel cells (SPFCs).Since a fuel cell normally generates a comparatively low voltage, several cells are usually connected to form stacks in order to achieve a higher overall voltage.

[0003] In a fuel cell, the electrolyte, which transports the ions, must typically be kept moist to ensure optimal performance. A fuel cell humidifier plays a key role in this process by ensuring that the water content in the gas mixture or process gas reaching the fuel cell is maintained at an optimal level. This is essential to ensure an efficient reaction between the fuel and the oxidizer. The fuel cell humidifier specifically helps protect the membrane used in the fuel cell from drying out, thus contributing to improving the durability and performance of the fuel cell. In PEM fuel cells, the electrolyte and membrane are formed as a single component, typically made of PFSA (perfluorosulfonic acid) films.

[0004] There is a constant need to improve the service life and efficiency of fuel cells.

[0005] Based on this situation, the current task is to identify measures that enable efficient and long-lasting fuel cells.

[0006] The present problem is solved by the features of the independent main claim. Advantageous embodiments are specified in the subclaims. To the extent technically feasible, the teachings of the subclaims can be combined arbitrarily with the teachings of the main and subclaims.

[0007] The object is therefore achieved by a humidification device for humidifying dry air, in particular for fuel cells, with a plurality of repeating cells connected to form a stack, wherein a cell has at least: a drying plate having a first flow system for introducing the dry air into a downstream system; a wet plate with a second flow system for discharging moist air from an upstream system; a moisture-permeable first membrane arranged between the dry plate and the wet plate for separating the first flow system from the second flow system and for transferring water from the second flow system to the first flow system; wherein the first membrane has a support structure extending into the second flow system for supporting the at least first membrane, wherein the support structure can be arranged within the wet plate in the region of the second flow system and counteracts a deformation of the at least first membrane in the direction of the adjacent second flow system, wherein a second moisture-permeable membrane is arranged between two successive cells and a wet plate of a second cell follows a dry plate of a first cell and vice versa.

[0008] The humidification device can provide the oxygen required for electrolysis from the ambient air, hereinafter referred to as dry air. The moisture required for efficient operation of the fuel cell, particularly water vapor, can be extracted from the fuel cell and added to the dry air. Water is produced in the fuel cell as a byproduct through the reaction of hydrogen with oxygen. This water, particularly in the form of water vapor, can be extracted from the cathode chamber by the humidification device, and a portion of it can be returned to the cathode chamber via the dry air.

[0009] In order to increase the moisture content in the dry air, a moisture-permeable membrane must be arranged in the cells of the humidification device between the dry plate and the wet plate. The pressure acting on the membrane in the first flow system of the dry plate is usually much higher than the pressure in the second flow system of the wet plate. This can deform the membrane in the direction of the second flow system and ultimately damage it. The application of the support structure to the first membrane has the advantageous effect that the support structure can be arranged as a spacer in the second flow system and thus counteracts the deformation of at least the first membrane. The support structure can be formed very delicately along the surface of the first membrane using thin and long wall segments.In principle, the thinner the supporting structures of the flow system, the larger the active surface and the volumetric humidification capacity. The support structure therefore fulfills an essential function, allowing sufficient humidity regulation of the dry air within the humidification device. Regulating the humidity of the dry air by means of the humidification device increases the efficiency and service life of fuel cells.

[0010] Advantageous aspects are explained below, and preferred modified embodiments are described further below. Explanations, particularly regarding advantages and definitions of features, are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be expressly stated.

[0011] The term "a plurality" is understood below to mean two or more. The "upstream or downstream system" can be, in particular, a fuel cell, a fuel cell assembly, and / or, particularly preferably, a cathode section or cathode chamber of the fuel cell.

[0012] The components that make up the cell, consisting of the dry plate, wet plate, and membrane, are flat components, in particular films or plates, in which the dimensions of their two main surfaces are at least one order of magnitude, in particular at least two orders of magnitude, larger than those of the four narrow edge surfaces. Thus, adjoining layers means that these layers are connected to one another with their main surfaces. The components can be connected directly, without any further intermediate layer, or indirectly, separated from one another by one or more intermediate layers, for example by an adhesive layer. The dry plate, the wet plate, and / or the membrane are made in particular of plastic. This makes these components easier to manufacture and lightweight. This particularly favors mobile applications, especially in automotive technology.

[0013] The support structure is arranged in conjunction with a plurality of stacked cells between two membranes within the second flow system and counteracts the deformation of both membranes in the direction of the adjacent second flow system.

[0014] The moisture introduced by the humidification device can be used in the fuel cell to humidify the electrolyte or the membrane.

[0015] An electrolyte in a fuel cell is a substance that enables the flow of ions between the electrodes. There are different types of fuel cells, including alkaline fuel cells (AFCs), polymer electrolyte fuel cells (PEMs, PEMFCs), phosphoric acid fuel cells (PAFCs), and many more. Each of these fuel cells has a specific electrolyte with different properties. For example, the PEMFC uses a polymer-based membrane (PEM) as its electrolyte.

[0016] A membrane in a fuel cell is a special barrier between the two electrodes (anode and cathode) that blocks the flow of electrons while allowing the flow of ions. In PEMFCs, the membrane is made of a proton-conducting polymer, typically a perfluorinated sulfonic acid polymer. This membrane enables the transport of protons (H + -ions) between the electrodes.

[0017] In some fuel cells, the electrolyte and membrane may be separate components. In other fuel cells, particularly PEM fuel cells, the electrolyte and membrane may be formed as a single component. The exact type and composition depends largely on the type of fuel cell.

[0018] Keeping the electrolyte and membrane moist is particularly important in fuel cells to ensure efficient performance. This is especially true for polymer electrolyte fuel cells (PEM, PEMFC), which are among the most widely used fuel cells.

[0019] Humidity regulation within the fuel cells can advantageously promote proton conduction. In PEMs or PEMFCs, the transport of protons (H + -ions) through the membrane. The membrane must therefore be kept moist so that the protons can be transported through more easily. Sufficient humidity is therefore important to maintain the membrane's conductivity.

[0020] Humidity control within fuel cells can advantageously prevent individual components from drying out. The membrane and / or electrolyte must not dry out, as this could impair performance and lead to damage to the fuel cell. Drying out could therefore promote membrane cracking and significantly limit proton transport.

[0021] Humidity control within fuel cells can advantageously improve temperature control. Humidity can also be used to regulate the fuel cell's operating temperature. An optimal humidity level can help stabilize operating conditions.

[0022] In a preferred embodiment of the above, the support structure is applied directly to the first membrane in a material-to-material bond. In particular, the support structure can be produced on the first membrane by screen printing or injection molding. In particular, the support structure can be produced on the first membrane by injection molding with thermoplastic or thermosetting materials, in particular liquid silicone injection molding (LSR injection molding). The screen printing process or the injection molding process can produce fine structures that result in greater efficiency of the humidification device.

[0023] In a preferred embodiment of the above, the first membrane and the second membrane are designed as a film, in particular as a plastic film. In particular, the second membrane is not provided with a support structure. The first membrane and the second membrane can be installed alternately in the cell or stack arrangement. The first membrane can thus support the second membrane by means of the support structure.

[0024] In a preferred embodiment of the above, it is provided that the support structure of the first membrane touches a second membrane arranged on the wet plate opposite the first membrane and thus counteracts a deformation of both membranes due to the greater pressure from the direction of the adjacent first flow systems.

[0025] In a preferred embodiment of the above-described, it is provided that the support structure forms a flow field for the optimized flow distribution of the moist air within the second flow system.

[0026] In a preferred embodiment of the above, the dry plate and the wet plate are designed as flat components and are in particular identical, with the wet plate being mirrored along its longitudinal axis or along its transverse axis and being directly or indirectly connected to the dry plate. The plates are in particular glued or welded to one another. Alternatively or additionally, the plates can be glued or welded to two opposing main surfaces of a common membrane.

[0027] In a preferred embodiment of the above, it is provided that the first membrane and the second membrane have two recesses for the dry air to flow through and two recesses for the moist air to flow through.

[0028] In a preferred embodiment of the above, the dry plate has at least one passage, separate from the first flow system, for the moist air to flow through, in particular in the direction of an upstream and / or downstream wet plate. In particular, the wet plate has at least one passage, separate from the second flow system, for the dry air to flow through, in particular in the direction of an upstream and / or downstream dry plate.

[0029] In a preferred embodiment of the above, it is provided that the recesses of the first membrane and the second membrane are arranged so as to overlap the first flow system of the dry plate and the at least one passage of the wet plate. In particular, it is provided that the recesses of the first membrane and the second membrane are arranged so as to overlap the second flow system of the wet plate and the at least one passage of the dry plate.

[0030] The object is further achieved by a fuel cell system comprising a fuel cell stack, in particular consisting of a plurality of fuel cells, with a plurality of cathode sections and a plurality of anode sections, wherein the air inlet and the air outlet of the plurality of cathode sections are connected to a humidification device according to the embodiments described above.

[0031] A preferred technical solution is explained in more detail below with reference to the accompanying drawings using preferred embodiments. The term "figure" is abbreviated to "Fig." in the drawings.

[0032] In the drawings Fig. 1 is a perspective view of a first embodiment of a humidifying device; Fig. 2 a plan view of individual components of the humidification device according to Fig. 1; Fig. 3 a plan view of a first membrane with a support structure; Fig. 4 a side view of the first membrane according to Fig. 3.

[0033] The described embodiment is merely an example which can be modified and / or supplemented in many ways within the scope of the claims.

[0034] Fig. Figure 1 shows a perspective view of a first embodiment of a humidification device 10 for humidifying dry air. The humidification device 10 consists of a plurality of cells 12, which are connected to one another to form a stack 14. The cell 12 has a dry plate 16, a wet plate 18, and a plurality of moisture-permeable membranes 20, 21. The dry plate 16 is designed to convey dry air 22 through a first flow system 24 according to Fig. 2. The first flow system 24 is defined by a frame element 26 of the dry plate 16 and two opposing membranes 20, 21. The frame element 26 can be at least partially or completely integrated into the dry plate 16 or connected to it as an independent component. The wet plate 18 is designed to direct moist air 28 through a second flow system 30 according to Fig. 2. The second flow system 30 is delimited by a frame element 32 of the wet plate 18 and two opposing membranes 20, 21. The frame element 32 can be at least partially or completely integrated into the wet plate 18 or connected to it as an independent component. A first membrane 20 is arranged between the dry plate 16 and the wet plate 18, which delimits the first flow system 24 from the second flow system 30. Water, in particular water vapor, can diffuse from the moist air 28 from the second flow system 30 into the first flow system 24 via the first membrane 20 and correspondingly increase the moisture content of the dry air 22.When assembling the individual cells 12 into a stack 14, each dry plate 16 is always followed by a corresponding wet plate 18, and vice versa, with a moisture-permeable first membrane 20 and a moisture-permeable second membrane 21 arranged alternately between the plates. In principle, the more cells 12 are connected to form a stack 14, the greater the performance of the humidification device 10.

[0035] Fig. 2 shows a plan view of individual components of the humidification device 10 according to Fig. 1. The dry plate 16, the wet plate 18, and the membranes 20, 21 are flat components that can be stacked on top of one another. The dry plate 16 and the wet plate 18 are identical in design. When assembling the cell 12, the wet plate 18 or the dry plate 16 is mirrored along its longitudinal axis L or transverse axis Q and then installed. The first flow system 24 is delimited laterally within the dry plate 16 by the frame element 26. The dry plate 16 also has two passages 34, separate from the first flow system 24, for the moist air 28 to flow through. The passages 34 serve as supply and discharge lines for supplying the second flow system 30 of the wet plate 18 with moist air 28. The second flow system 30 is delimited laterally within the wet plate 18 by the frame element 32.The wet plate 18 additionally has two passages 36, separate from the second flow system 30, for the dry air 22 to flow through. The passages 36 serve as supply and discharge lines for supplying the first flow system 24 of the dry plate 16 with dry air 22. The membranes 20, 21 have corresponding recesses 38 for the dry air 22 to flow through and recesses 40 for the moist air 28 to flow through. The recesses 38 of the membranes 20, 21 are arranged in the cell 12 so as to overlap with the first flow system 24 of the dry plate 16 and with the passages 36 of the wet plate 18. The recesses 40 of the membranes 20, 21 are arranged in the cell 12 overlapping with the second flow system 30 of the wet plate 18 and with the passages 34 of the dry plate 16.

[0036] Fig. Figure 3 shows a top view of a first membrane 20 with a support structure 42 designed to support at least one membrane 20, 21. The pressure acting on the first and second membranes 20, 21 in the first flow system 24 of the dry plate 16 is greater than the pressure in the second flow system 30 of the wet plate 18. As a result, the membranes 20, 21 can be deformed in the direction of the second flow system 30 and ultimately damaged.

[0037] Attaching the support structure 42 to the first membrane 21 and positioning it in the second flow system 30 counteracts the deformation of at least one membrane 20, 21. The support structure 42 can be applied to the first membrane 21 by means of screen printing or injection molding. This allows the Fig. 3 or geometrically similar thin-walled structures. This facilitates the establishment of an optimal flow field, which can improve the performance of the humidification device.

[0038] Fig. 4 shows a side view of the first membrane 20 according to Fig. 3. The support structure 42 extends toward the wet plate 18. When installed, the support structure is located within the second flow system 30. The support structure 42 can support both the first membrane 20 and the opposite second membrane 21 against each other, preventing the membranes 20, 21 from deforming toward the second flow system 30. To maintain the air flow within the second flow system 30, the support structure 42 has individual wall sections. This allows the moist air 28 to continue flowing along the membranes 20, 21. List of reference symbols 10 Humidification device 12 cell 14 stacks 16 Dry plate 18 wet plate 20 first membrane 21 second membrane 22 dry air 24 first flow system 26 frame element 28 humid air 30 second flow system 32 frame element 34 Passage 36 passage 38 recess 40 recess 42 Support structure L Longitudinal axis Q Transverse axis

Claims

[1] Humidification device for humidifying dry air (22), in particular for fuel cells, with a plurality of repeating cells (12) connected to form a stack (14), wherein a cell (12) has at least: a drying plate (16) with a first flow system (24) for introducing the dry air (22) into a downstream system; a wet plate (18) with a second flow system (30) for discharging moist air (28) from an upstream system; a moisture-permeable first membrane (20) arranged between the dry plate (16) and the wet plate (18) for separating the first flow system (24) from the second flow system (30) and for transferring water from the second flow system (30) into the first flow system (24); wherein the first membrane (20) has a support structure (42) extending into the second flow system (30) for supporting the at least first membrane (20), wherein the support structure (42) can be arranged within the wet plate (18) in the region of the second flow system (30) and a deformation of the at least first membrane (20) in the direction of the adjacent second flow system (30), wherein a second moisture-permeable membrane (21) is arranged between two successive cells (12) and a dry plate (16) of a first cell (12) is followed by a wet plate (18) of a second cell (12) and vice versa. [2] Humidifying device according to claim 1, wherein the support structure (42) is applied directly to the first membrane (20) in a material-to-material manner, wherein in particular the support structure (42) can be produced on the first membrane (20) by means of screen printing or injection molding, in particular by means of LSR injection molding, wherein in particular the support structure (42) can be applied to the first membrane by means of injection molding with thermoplastic or thermosetting materials, in particular liquid silicone injection molding (LSR injection molding). [3] Humidifying device according to claim 1 or 2, wherein the first membrane (20) and the second membrane (21) are designed as a film, in particular as a plastic film, wherein in particular the second membrane (21) has no support structure (42). [4] Humidification device according to one of the preceding claims, wherein the support structure (42) of the first membrane (20) contacts a second membrane (21) arranged on the wet plate (18) opposite the first membrane (20) and counteracts a deformation of both membranes (20, 21) due to the greater pressure from the direction of the adjacent first flow systems (24). [5] Humidification device according to one of the preceding claims, wherein the support structure (42) forms a flow field for optimized flow distribution of the moist air (28) within the second flow system (30). [6] Humidification device according to one of the preceding claims, wherein the dry plate (16) and the wet plate (18) are designed as flat components and in particular are identical, wherein the wet plate (18) is connected indirectly or directly to the dry plate (16) in a mirrored manner along its longitudinal axis (L) or along its transverse axis (Q). [7] Humidification device according to one of the preceding claims, wherein the first membrane (20) and the second membrane (21) each have two recesses (38) for the dry air (22) to flow through and two recesses (40) for the moist air (28) to flow through. [8] Humidifying device according to one of the preceding claims, wherein the dry plate (16) has at least one passage (34) separate from the first flow system (24) for the moist air (28) to flow through, in particular in the direction of an upstream and / or downstream wet plate (18), wherein in particular the wet plate (18) has at least one passage (36) separate from the second flow system (30) for the dry air (22) to flow through, in particular in the direction of an upstream and / or downstream dry plate (16). [9] Humidification device according to claim 7 and 8, wherein the recesses (38) of the first membrane (20) and the second membrane (21) are arranged to overlap with the first flow system (24) of the dry plate (16) and with the at least one passage (36) of the wet plate (18), wherein in particular the recesses (40) of the first membrane (20) and the second membrane (21) are arranged to overlap with the second flow system (30) of the wet plate (18) and with the at least one passage (34) of the dry plate (16). [10] Fuel cell system, comprising: a fuel cell stack, in particular consisting of a plurality of fuel cells, with a plurality of cathode sections and a plurality of anode sections, wherein the air inlet and the air outlet of the plurality of cathode sections are connected to a humidification device (10) according to one of claims 1 to 9.

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