FUEL CELL SYSTEM AND METHOD FOR USING A FUEL CELL SYSTEM

Abstract

A fuel cell system comprises: a fuel cell stack with a plurality of membrane electrode assemblies; a media supply channel for supplying gas from an inlet side to the membrane electrode assemblies; and a structure arranged on a side wall of the media supply channel and projecting into the media supply channel. The structure extends in a direction perpendicular to the side wall of the media supply channel by between 5% and 50% of the width of the media supply channel in that direction, or occupies between 5% and 50% of the flow cross-section of the media supply channel.The media supply channel has a longitudinal axis along which the gas can flow to the individual membrane electrode units, the structure having a first surface on its inlet side and a second surface on its outflow side, the second surface having a first section adjacent to the side wall and a second section adjoining the first section and being further away from the side wall than the first section, the first section of the second surface being designed such that liquid on the second surface is directed from the side wall to the second section of the second surface.

Description

[0001] The present invention relates to a fuel cell system and a method for using a fuel cell system.

[0002] A typical fuel cell system comprises a fuel cell stack formed by several membrane electrode assemblies. Gas flows from an inlet side of a media supply channel to the membrane electrode assemblies. Further details regarding the general structure and operating principle of a fuel cell system are not explained here, as these are known from the prior art.

[0003] The problem of flooding of a membrane electrode assembly (MEA) is also already known. Such flooding can be caused, for example, by liquid (usually water) that has condensed on a side wall of the media supply channel. The liquid forms a film on the wall, particularly (initially) upstream of the MEA, and this film flows from the inlet side of the media supply channel towards the MEA. This flow may be relatively slow, especially under certain operating conditions such as a low gas flow velocity in the media supply channel. When the liquid forming the film reaches the MEA, particularly the first MEA in the direction of gas flow, it can penetrate and flood this MEA.

[0004] Flooding negatively impacts the fuel cell's performance because the liquid hinders effective contact between the hydrogen used as fuel and the electrode. This leads to reduced current flow and decreased electrical output. Furthermore, flooding can also cause corrosion and damage to the fuel cell's components.

[0005] To avoid or reduce flooding, various strategies have been used in the prior art, such as the use of drainage and evaporation systems to remove water from the fuel cell.

[0006] An example of such a drainage system is known from US 2015 / 0093673 A1. According to this document, a porous element is positioned upstream of a fuel cell stack on the inlet side. This element is designed to be permeable to gas but not to liquid. Liquid present in the gas stream on the inlet side is intended to condense on the surface of the porous element and flow by gravity into a collection tray. In this way, the liquid is kept away from the individual fuel cells of the fuel cell stack.

[0007] Another problem with the prior art is that after use of a fuel cell system, water collects in the area of ​​the media supply channel without being able to leave the fuel cell system (e.g., drain away). This poses a particular risk at sub-zero temperatures, as the water may freeze and potentially damage the fuel cell system. This affects not only the membrane electrode assemblies but also other components where water can stagnate. An example of this is the drip tray of the aforementioned US 2015 / 0093673 A1.

[0008] US 2010 / 0209798A1 discloses a fuel cell stack wherein each individual energy-generating cell of the fuel cell stack has a water drainage element from which condensed water can fall downwards in the direction of gravity. JP 2009-129545A discloses a fuel cell system with a barrier for condensed water, wherein the water can flow out through an opening in the barrier.

[0009] Against this background, it is a task of the present disclosure to provide an alternative and, if necessary, improved technique for one or more of the problems discussed above.

[0010] The solution to this problem is achieved according to the teaching of the independent claims. Various embodiments and further developments of the solution are the subject of the dependent claims.

[0011] Aspects of the invention are defined in the claims.

[0012] A first aspect of the present disclosure relates to a fuel cell system comprising: a fuel cell stack with a plurality of membrane electrode assemblies; a media supply channel for supplying gas from an inlet side to the membrane electrode assemblies; and a structure that is located on a side wall of the media supply channel and projects into the media supply channel, wherein the structure extends in a direction perpendicular to the side wall of the media supply channel between inclusive 5% and inclusive 50% of the width of the media supply channel in the direction perpendicular to the side wall of the media supply channel, or wherein the structure occupies between inclusive 5% and inclusive 50% of the flow cross-section of the media supply channel; wherein the media supply channel has a longitudinal axis along which the gas can flow to the individual membrane electrode units, wherein the structure has a first surface on its inflow side and a second surface on its outflow side, wherein the second surface has a first section adjacent to the side wall, and a second section adjoining the first section and being further away from the side wall than the first section, wherein the first section of the second surface is designed such that liquid on the second surface is directed from the side wall to the second section of the second surface.

[0013] According to the first aspect of the disclosure, the first section of the second surface is designed such that fluid on the second surface is directed from the side wall to the second section of the second surface. This helps to minimize the accumulation of fluid, particularly water, on the second surface (and especially near the side wall or in the first section of the second surface), particularly when the fuel cell system is oriented such that the second surface is above the first surface with respect to gravity, and especially when the second surface slopes more or less continuously towards the center of the media supply channel. Fluid that accumulates, for example, after the fuel cell system is switched off (or...)(If there is no upward gas flow) the fluid is moved downwards by gravity in the media supply channel – either in free fall or along the side wall of the media supply channel – and can then be deflected away from the side wall by the second surface. This can also reduce the likelihood of fluid accumulating, for example, in the lowest membrane electrode assembly and either flooding it or causing other damage. Such damage can occur particularly from fluids that, for example, freeze and expand after the fuel cell system is switched off at certain temperatures, as is the case with water.

[0014] The structure can be designed as a separate component or can be (at least partially) integral with the side wall of the media supply channel, for example through a specific shaping of the side wall.

[0015] Because the structure protrudes into the media supply channel, it effectively forms a barrier or flow resistance. This allows any liquid that accumulates on the first surface during operation of the fuel cell system to be drawn into the gas flow in the media supply channel, particularly in the form of small droplets. The absorption or entrainment of the liquid by the gas flow is facilitated by the structure's constriction within the media supply channel, thus increasing the gas flow velocity in the area of ​​the structure. In this way, the liquid can be distributed across multiple membrane electrode assemblies, ensuring that no single assembly is flooded and that a sufficiently large area remains available for gas exchange in all assemblies.The fact that a (comparatively small amount of) liquid is absorbed by several membrane electrode units in this way is not problematic, or rather less problematic than flooding a single membrane electrode unit, as the inventor discovered in experiments.

[0016] According to the present disclosure, a porous element, such as that known from US 2015 / 0093673 A1, is therefore unnecessary. Gas can thus flow from the media supply channel to the membrane electrode assemblies without having to pass through a porous structure. The gas supply is therefore not obstructed by a porous structure. Liquid that accumulates on the first surface during operation of the fuel cell system can also reach the membrane electrode assemblies, which, as described above, is considered unproblematic.

[0017] Good or at least satisfactory results can also be achieved by selecting a structure extension perpendicular to the side wall within the range of 5% to 50% of the width of the media supply channel in the direction perpendicular to the side wall of the media supply channel, based on the inventor's experiments. If the structure extension perpendicular to the side wall is chosen to be less than 5%, this structure may not be able to fulfill its purpose (or one of its purposes) sufficiently, namely, directing liquid on the second surface away from the side wall to the second section of the second surface and / or directing liquid (on the first surface) into the gas stream and / or the lateral discharge of a wall film, as will be explained below, and thus distributing the liquid across several membrane electrode units.If, on the other hand, the extent of the structure perpendicular to the side wall is chosen to be greater than 50%, the structure may represent an excessively large flow obstruction, which could on the one hand impede the gas flow to the membrane electrode units and on the other hand lead to liquid droplets that were already absorbed in the gas flow and could have been distributed by it in an unproblematic way to several membrane electrode units being deposited on the structure and could combine to form larger liquid droplets.

[0018] The “width of the media supply channel in the direction perpendicular to the side wall of the media supply channel” is also referred to here as the “depth of the media supply channel”.

[0019] The first surface and / or the second surface can be, in particular, a main surface or surfaces of the structure, i.e., in particular a surface or surfaces that have a larger area than others or most of the outer surfaces of the structure.

[0020] The term "direction perpendicular to the side wall of the media supply channel" refers to a section of the side wall where the structure is located. The point or area on the side wall where the structure is located can be defined as the point or area where the center of the structure is situated on the side wall. This can be particularly relevant if the side wall is not flat where the structure is located. Alternatively, an average value can be assumed for the orientation of the side wall, for example, over a portion or the entire area where the structure is located.

[0021] An average value or direction can also be assumed for the longitudinal axis of the media supply channel. Furthermore, it should be assumed that the gas does not flow uniformly through the media supply channel. For example, eddies or similar features may form in the gas flow. Nevertheless, a flow direction can generally be assigned to the gas flow, which essentially coincides with the longitudinal axis of the media supply channel. The terms "inlet side," "downstream," "upstream," and the like should be understood accordingly.

[0022] The following describes various exemplary embodiments of the fuel cell system, which, unless expressly excluded or technically impossible, can be combined with each other as desired and with the second and / or third aspect of the present disclosure described below.

[0023] The extent of the structure in the direction perpendicular to the side wall of the media supply channel can be selected such that it is at least 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% and / or at most 45%, 40%, 35%, 30%, 25%, 20%, 15% or 10% of the width of the media supply channel in the direction perpendicular to the side wall of the media supply channel, or The structure can be designed to occupy at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, or 45% and / or at most 45%, 40%, 35%, 30%, 25%, 20%, 15%, or 10% of the flow cross-section of the media supply channel. Combinations of these values ​​that are technically impossible (such as "at least 30% and at most 10% of the width of the media supply channel") should be disregarded.

[0024] It is possible that for certain applications, a particular range of values ​​may be more suitable than another. Suitable values ​​can be determined through experimentation.

[0025] The structure is positioned further upstream in the gas flow direction within the media supply channel than all membrane electrode assemblies of the fuel cell system. This ensures that flooding can be prevented with respect to all membrane electrode assemblies.

[0026] In the fuel cell system, one or more or all points lie on a line along which the second surface borders the side wall, - further downstream than one or more or all points of the second surface at its edge furthest from the side wall.

[0027] A majority of normal vectors on the second surface, which have a component in the direction of the gas flow along the longitudinal axis, can either be aligned parallel to the longitudinal axis or have a component pointing towards the center of the media supply channel.

[0028] By placing points on the second surface closer to the side wall further downstream than points on the second surface located further away from the side wall, the probability of the gas flow forming vortices with an upstream component on the downstream side of the structure can be reduced. Such vortices could cause liquid carried by the gas flow to condense on the second surface of the structure. Furthermore, this can promote the flow of liquid from the side wall to the second section of the second surface.

[0029] Regarding the term "majority of normal vectors on the second surface," it should be noted that any surface can, of course, be divided into infinitely many regions, and each of these regions can be assigned a normal vector. In that sense, the second surface could, in principle, have infinitely many normal vectors. However, here it means that the second surface should be conceptually divided into an arbitrary (but finite) number of regions, and each of these regions should be assigned a normal vector. Subsequently, the orientation of these normal vectors is examined, and it is determined whether more than half of these normal vectors satisfy the aforementioned criterion.

[0030] The term "component in the direction of gas flow" means that only those components (of normal vectors) that are aligned with the direction of gas flow should be considered. Components opposite to the direction of gas flow should not be considered. In other words, of two opposing vectors, at most one can fulfill the criterion of a "normal vector on the second surface that has a component in the direction of gas flow along its longitudinal axis".

[0031] The structure may have a detachment edge on its side facing away from the side wall. This edge can be as sharp as possible, as this can help liquid droplets located at the detachment edge to be carried along by the gas flow instead of running along the downstream-oriented side of the structure, especially the second surface, towards the side wall.

[0032] To further contribute to liquid droplets being carried along by the gas flow and prevented from running downstream (i.e., the second) side of the structure, the (second) side facing away from the inlet can have an undercut. While this may mean that some liquid, which moves downwards in the media supply channel due to gravity after the fuel cell system is shut down, for example, could collect in this undercut, this may be acceptable in some applications, especially if the undercut is relatively small.

[0033] The structure can have a first area furthest from the side wall and a second area adjacent to the side wall. These can be designed differently or have different properties, for example, regarding their dimensions or material composition, but they can also be identical with respect to some or all properties, for example, the inclination of their surfaces relative to the longitudinal axis of the media supply channel.

[0034] For the purposes of this disclosure, the term "first region of the structure, which is furthest from the side wall" preferably refers to a region that occupies a large part of the width of the side wall (in a direction parallel to a region of the side wall on which the structure is arranged). If the structure has further sections that are even further from this region of the side wall but have only a comparatively small width (again in a direction parallel to a region of the side wall on which the structure is arranged), these are preferably not to be taken into account and are therefore not included in the first region.

[0035] The structure can extend across the entire width of the media supply channel in one direction along the side wall, particularly in the first and / or second area. However, it is not the case that the structure must extend across the entire width of the media supply channel at all distances from the side wall. For example, the structure may extend across the entire width of the media supply channel where it abuts the side wall (i.e., in the second area), while this is not necessarily the case for positions further away from the side wall.

[0036] If the structure extends across the entire width of the media supply channel, at least where it abuts the side wall, liquid located in a region of the first surface of the structure adjacent to the side wall must be moved away from the side wall to enter a section of the media supply channel downstream of the structure. This can therefore contribute to the addition of liquid to the gas flow, and preferably to a central region of the media supply channel.

[0037] However, it is also possible that the structure, particularly in the second area, occupies less than the entire width of the media supply channel in one direction along the side wall. In other words, besides the area where the structure is located on the side wall, a portion of the side wall may remain unobstructed.

[0038] Due to the narrower width of the structure in the second area compared to the width of the media supply channel, an opening can be created through which liquid that accumulates on the first surface during operation of the fuel cell system can flow downstream in the direction of gas flow towards the membrane electrode assemblies. In particular, if the structure—possibly together with the side wall—forms a channel, this channel can open into the opening, allowing liquid to flow out of the channel through the opening. The opening is preferably significantly narrower than the width of the media supply channel along the side wall. For example, the width of the opening can be up to 30%, 20%, 15%, 10%, or 5% of the width of the media supply channel. Furthermore, the opening can be located at a lateral edge of the structure, thus not dividing the structure into two sections (although this would also be possible).When fluid flows through such a laterally arranged opening towards the membrane electrode assemblies, it is delivered in a relatively concentrated form to the assemblies, particularly to the first assemblies located downstream of the structure, within a short area. This alone ensures that, at least initially, a large portion of the width of the assemblies, or at least the first assemblies, remains unobstructed and available for gas absorption. Because the fluid is concentrated in a relatively small area, most of the fluid reaching the first assemblies is passed on to the second assemblies and from there to the third (and so on), instead of all the fluid immediately flooding the first assemblies.Thus, each membrane electrode unit can absorb some liquid, which is not a problem because, or as long as, a sufficiently large area remains for gas exchange in each of these membrane electrode units.

[0039] The first surface, particularly in the first region, can be inclined such that a first point on the first surface, located particularly in the first region and situated at a greater distance from the side wall than a second point on the first surface, is located further upstream in the direction of gas flow in the media supply channel than the second point. In this way, the first surface—optionally together with the side wall—can form a type of channel as described above. Liquid forced against the first surface by the gas flow can thus collect in this channel. The second point or channel can be located directly adjacent to the side wall (and partially formed by it) or at a distance from a section of the side wall where the structure is located.

[0040] However, the first surface can also be inclined, particularly in the first region, such that a first point on the first surface, located especially in the first region and at a greater distance from the side wall than a second point on the first surface, located especially in the first region, lies further downstream in the direction of gas flow in the media supply channel than the second point. In other words, if we imagine a straight line through the first and second points and a liquid droplet located at the second point that can only move—frictionlessly—along this line, a force acting on the liquid droplet in the direction of flow will cause the liquid droplet to move towards the first point.Such an inclination of the first surface can therefore cause liquid located on the first surface, and especially in the first region, to be carried by the gas flow towards the edge of the structure furthest from the side wall, i.e., towards the center of the flow channel. Liquid reaching this edge of the structure can then potentially be carried along by the gas flow and transported, for example as mist or in the form of small droplets, to the membrane electrode assemblies.

[0041] The structure can be designed such that a normal vector on the first surface in the first region of the structure is inclined at an angle α to the longitudinal axis of the media supply channel, where the angle α is between 0° and 60° inclusive. In particular, the angle α can be at most 50°, 40°, 30°, 25°, 20°, 15°, 10°, or 5°.

[0042] By designing the structure with an angle α of a maximum of 60° between a normal vector on the first surface in the first region of the structure and the longitudinal axis of the media supply channel (and possibly depending on the other design of the structure explained below), two effects or mechanisms can be favored, which will be explained in more detail below.

[0043] The first effect or mechanism manifests itself in the fact that liquid which accumulates on the first surface during the operation of the fuel cell system can flow away from the side wall and be fed into the gas flow in the media supply channel, especially in the form of small droplets, as already described above.

[0044] According to the second effect or mechanism, liquid that accumulates on the first surface during operation of the fuel cell system can, by appropriately tilting the first surface, be directed to one side of the membrane electrode assemblies, particularly through an opening mentioned above, in such a way that the liquid is not only absorbed by a single membrane electrode assembly, but by several membrane electrode assemblies. In this way, the liquid is also distributed across several membrane electrode assemblies, which, as described above, is considered unproblematic or less problematic than flooding a single membrane electrode assembly.

[0045] The relatively small angle α of a maximum of 60° offers the advantage that the structure, in the longitudinal direction of the media supply channel, does not need to be excessively large for a given or desired extent perpendicular to the side wall of the media supply channel – for example, 50% of the width of the media supply channel in the direction perpendicular to this side wall. In the extreme case of α = 0°, it is possible, for example, that the extent of the structure in the longitudinal direction of the media supply channel is only equal to the material thickness of the structure.

[0046] The structure, or the first surface, does not need to have the same slope throughout its initial region; it does not need to be (continuously) planar, but can also be angled or curved. Thus, the term "normal vector on the first surface in a first region of the structure" can be understood as a vector perpendicular to a plane that is tangent to the first surface and assigned to a (potentially arbitrary) point in the first region. According to an alternative definition, the "angle of inclination α of a normal vector" can also be considered the average value of the inclination of normal vectors at several or all points of the first surface in the first region of the structure.

[0047] The first area, with respect to the extension of the structure in a direction perpendicular to the side wall of the media supply channel, can be located in an area at a distance from the side wall of 50% to 100% of this extension.

[0048] The first area can also be smaller; for example, it can extend from the side wall at a distance of 60%, 70%, 80%, or 90%, up to 100% of the structure's extent. Furthermore, the first area does not necessarily have to extend to a distance of 100% from the side wall, but could, for instance, only reach a distance of 90% or 95% of the structure's extent in a direction perpendicular to the side wall of the media supply channel.

[0049] Similarly, the second section of the second surface, relative to the extent of the second surface in a direction perpendicular to the side wall of the media supply channel, can lie in an area located at a distance from the side wall of 50% to 100% of this extent. However, the second section of the second surface can also be smaller; for example, it can extend at a distance from the side wall of 60%, 70%, 80%, or 90%, each up to 100% of this extent of the structure. Furthermore, the second section of the second surface need not necessarily extend to a distance of 100% from the side wall, but could, for example, only reach a distance of 90% or 95% of the extent of the structure in a direction perpendicular to the side wall of the media supply channel.

[0050] A second aspect of the present disclosure relates to a fuel cell system comprising: a fuel cell stack with a plurality of membrane electrode assemblies; a media supply channel for supplying gas from an inlet side to the membrane electrode assemblies; and a structure that is located on a side wall of the media supply channel and projects into the media supply channel, wherein the structure has a first surface on its inflow side, wherein the first surface has a border configured such that any liquid that accumulates on the first surface during operation of the fuel cell system is fed to the gas flow in the media supply channel and / or distributed to the majority of membrane electrode assemblies.

[0051] This edge of the first surface can, for example, take the form of the separation edge described above, particularly at a point furthest from the side wall. However, the edge of the first surface can also be an edge of the structure that forms a boundary of the lateral opening described previously. In both cases, the liquid can ultimately be distributed to the majority of membrane electrode assemblies, either by being carried along by the gas flow or by being released in a limited area towards the first membrane electrode assembly, from where a portion, and in particular a large portion, is passed on to subsequent membrane electrode assemblies.

[0052] A third aspect of the present disclosure relates to a method for using a previously described fuel cell system, wherein both gas in the media supply channel and liquid that accumulates on the first surface during operation of the fuel cell system are enabled to reach the membrane electrode assemblies.

[0053] In contrast to the prior art, this approach does not attempt to keep liquid away from the membrane electrode assemblies, for example, by using a porous structure that allows gas to pass from the media supply channel to the membrane electrode assemblies but is essentially impermeable to liquid. Instead, the liquid is distributed across a plurality of membrane electrode assemblies. Among other things, this can simplify the design of the fuel cell system and / or reduce flow resistance.

[0054] An arrangement as described herein can be located on an anode side and / or on a cathode side of a fuel cell system.

[0055] The features and advantages described in relation to the first aspect of the revelation and its advantageous design also apply, at least where technically appropriate, to the second and third aspects of the revelation and their advantageous design, and vice versa.

[0056] Any terms used herein, such as "comprises," "includes," "includes," "features," "has," "with," or any other variant thereof, are intended to cover non-exclusive inclusion. For example, a method or apparatus that includes or features a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent in such method or apparatus.

[0057] Furthermore, unless explicitly stated otherwise, "or" refers to an inclusive "or" and not an exclusive "or". For example, a condition A or B is satisfied by each of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0058] The terms "ein" or "eine," as used here, are defined as "at least one." The terms "ein anderer" and "ein Weitere," as well as any other variant thereof, are to be understood as "at least one more."

[0059] The term "plural", as used here, is to be understood in the sense of "two or more".

[0060] The terms “configured” or “set up” to perform a specific function (and their respective variations) are to be understood in the present context as meaning that the corresponding device is already in a configuration or setting in which it can perform the function, or at least it is adjustable – i.e., configurable – so that it can perform the function after appropriate configuration.

[0061] Further features, advantages and applications of the revelation will be revealed in the following description in connection with the figures, in which the same reference signs are consistently used for the same or corresponding elements of the revelation.

[0062] For the sake of clarity, the figures are at least partially schematic or greatly simplified and not to scale. Fig. Figure 1 shows a sectional view (of a first side) of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 2 shows a sectional view (from above) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 3 shows a sectional view (from a first side) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 4 shows a sectional view (from a first side) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 5 shows a sectional view (from a first side) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 6 shows an illustration of an angle of inclination, Fig. Figure 7 shows a sectional view (from a first side) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 8 shows a sectional view (from a first side) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 9 shows a sectional view (from above) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 10 shows a sectional view (from above) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 11 shows a sectional view (from a second side) of a section of a fuel cell system according to one embodiment of the present disclosure, Fig. Figure 12 shows a sectional view (from above) of a section of a fuel cell system according to one embodiment of the present disclosure.

[0063] Fig. Figure 1 shows a sectional view (of a first side) of a fuel cell system 1 according to an embodiment of the present disclosure. The fuel cell system 1 has an upper end plate 8 and a lower end plate 9, between which several membrane electrode assemblies 2 are accommodated. Together these form a fuel cell stack. The membrane electrode assemblies 2 and the end plates 8, 9 are located at the left edge of the Fig. 1 cut away.

[0064] In the right half of the Fig. 1 is a media supply channel 3, whose longitudinal axis 20 is shown as a dashed line. The media supply channel 3 serves to supply gas to the membrane electrode units 2. In Fig. Figure 1 shows the gas inlet side at the bottom. The direction of gas flow 7 is illustrated by an upward-pointing arrow 7. It should be noted that gas does not normally flow homogeneously upwards exactly along the direction of arrow 7, but may deviate from the direction illustrated by arrow 7. For example, the gas flow may exhibit a rotation around the direction illustrated by arrow 7. This rotation is indicated by the long arrow in the media supply channel 3. Nevertheless, arrow 7 indicates the general or tendency of the gas flow.

[0065] The lowest of the membrane electrode units 2 is additionally identified by the reference symbol 2a. Viewed in the direction of flow, this is the first membrane electrode unit 2.

[0066] Below the first membrane electrode unit 2a, a lower end plate 9 is attached, and below this, a media distribution plate 10.

[0067] The general structure of a fuel cell system with a fuel cell stack, a media supply channel, end plates and a media distribution plate is known in the prior art and is therefore not described further.

[0068] A structure 4 is arranged on the lower end plate 9, projecting into the media supply channel 3. A portion of the lower end plate 9 is also shown to the right of the media supply channel 3, as is the case for the membrane electrode assemblies. This representation is due to the fact that Fig. Figure 1 shows a cross-sectional view, with the section running through the media supply channel 3. The in Fig. The structure 4 shown in Figure 1 is arranged or attached to a section of the side wall 13 of the media supply channel 3, which is defined, among other things, by the lower end plate 9, and above which the membrane electrode units 2 are also arranged. Further details of this structure 4 are explained in connection with the other figures.

[0069] Fig. 1 also indicates an accumulation of liquid 5, for example water. In the Fig. In the example shown, the liquid 5 has mainly accumulated on the side wall 13 of the lower end plate 9 and the media distribution plate 10, as well as on the side of the structure 4, which is in Fig. 1 is shown on the underside of structure 4, accumulated. The liquid 5 can, for example, be from a Fig. The liquid originates from the section of the fuel cell system 1 not shown, which is located below the media distribution plate 10. This section of the fuel cell system, not shown, could, for example, be gas supply lines on which liquid has condensed, having possibly been previously carried by the gas flow and subsequently moving along a corresponding wall as far as the side wall 13 of the media distribution plate and the lower end plate 9 due to the gas flow.

[0070] In a fuel cell system that does not have the structure 4 projecting into the media supply channel 3 but is otherwise identical in construction to the one in Fig. If the fuel cell system 1 shown in Figure 1 were configured as described above, there would be a risk that the liquid accumulation 5 would move towards the first membrane electrode assembly 2a and flood it (or one of the two media sides, for example, the anode channel of the membrane electrode assembly 2a), as described above. The structure 4 is intended to counteract such flooding. According to the Fig. In the embodiment shown in Figure 1, the liquid 5 is prevented by the structure 4 from flowing further along the side wall 13 to the first membrane electrode assembly 2a. Instead, the liquid 5 flows in the direction of the central axis 20 of the media supply channel 3 to the edge of the structure 4. Fig. 1, so to the right.

[0071] The edge of the structure 4 furthest from the side wall 13 can be relatively sharp-edged, as will be explained below in connection with the further figures. This edge thus forms a separation edge. The gas flow past this separation edge can entrain the liquid 5 and carry it further into the media supply channel 3 in the form of small droplets 6. These liquid droplets 6 then distribute themselves among several membrane electrode assemblies 2. This prevents the first membrane electrode assembly 2a from becoming flooded.

[0072] The fuel cell system 1 of the Fig. Figure 1 is shown in an orientation where the gas flows into the media supply channel 3 from below. However, the fuel cell system 1 can also be used in a different orientation. Nevertheless, for the sake of a concise presentation, terms such as top, bottom, left, and right are used here in a manner consistent with the representation in Figure 1. Fig. The orientation of the fuel cell system shown in 1 is consistent.

[0073] The same applies to the other characters and the entire description.

[0074] In Fig. Figure 1 shows a coordinate system in the lower left corner, indicating the x, y, and z directions. The y-direction runs along the longitudinal axis of the media supply channel 3. The x-direction is perpendicular to the side wall 13, and the z-direction is perpendicular to the x- and y-directions, i.e., in this case, horizontal and parallel to the side wall 13. The in Fig. The indicated coordinate system also applies to the Fig. 3 to 5, 7 and 8.

[0075] Fig. Figure 2 shows a sectional view (from above) of a section of a fuel cell system 1 according to one embodiment of the present disclosure. Left in Fig. 2 shows another coordinate system. This coordinate system, which is linked to the one in Fig. The fact that the coordinate system shown in 1 is consistent also applies to the Fig. 9, Fig. 10 and Fig. 12.

[0076] The in Fig. The section shown in Figure 2 runs in a horizontal plane through the widest point of structure 4 in the x-direction. Fig. 1. Fig. Figure 2 also shows the entire cross-section of the media supply channel 3, as well as a section of the lower end plate 9. A large part of the lower end plate 9 is shown due to the fracture line representation in Fig. 2 not shown.

[0077] Media feed channel 3 has in Fig. 2 a roughly rectangular cross-section with rounded corners, although other shapes are also possible. The boundary of the media supply channel 3 on the left side is the side wall 13 or that side wall section 13 on which the structure 4 is arranged. The structure 4 projects from this left section of the side wall 13 in the x-direction. The width of the media supply channel 3 in the z-direction is designated by reference numeral 11, and the depth of the media supply channel 3 in the x-direction by reference numeral 12. As shown in Fig. As can be seen in Figure 2, the structure 4 extends over the entire width 11 of the media supply channel 3 along the side wall 13. Perpendicular to the side wall 13, however, it extends only over a part (about 30%) of the depth 12 of the media supply channel 3.

[0078] Fig. Figure 3 shows a sectional view (of a first side) of a section of a fuel cell system 1 according to one embodiment of the present disclosure. The Fig. Section 3 shown corresponds to an enlarged representation of the corresponding section in Fig. 1. The underside of structure 4, i.e., on the inlet side, bears the reference numeral 14. This underside 14 is also referred to here as the first surface 14. The section of the first surface 14 furthest from the side wall 13 is designated with the reference numeral 18. In this section 18, the first surface 14 runs horizontally, i.e., it lies in an xz-plane. This is indicated by the normal vector 17a, which is perpendicular to the first surface 14 in section 18 and thus points in a direction parallel to the longitudinal axis 20 of the media supply channel 3. In the example shown, the first surface 14 lies entirely in a plane. In variants not shown, however, the first surface 14 can also be curved or angled. On the side opposite the first surface 14, i.e., on the downstream-oriented side, the structure 4 is bounded by a second surface 15, which in this example is angled.Section 15b of this second surface 15 at the right edge lies in an xz-plane, while the remaining, left section 15a runs obliquely. Section 15a is referred to here as the first section (of the second surface 15) and section 15b as the second section (of the second surface 15). Due to the finite thickness of the structure 4 in this example, the edge 16 of the structure 4 furthest from the side wall 13 is represented as a perpendicular surface 16 that lies in a yz-plane.

[0079] The normal vector 17b, which is perpendicular to the first section 15a of the second surface 15, does not point in a direction parallel to the longitudinal axis 20 of the media supply channel 3, but has a component oriented towards the center of the media supply channel 3 (or away from the side wall 13), i.e., in the x-direction. A normal vector 17b (not shown) that is perpendicular to the second section 15b of the second surface 15 would point in a direction parallel to the longitudinal axis 20 of the media supply channel 3.

[0080] At the upper end of the rim 16, or at the right end of the second surface 15, an edge 21 runs along the z-direction, i.e., parallel to the side wall 13 and perpendicular to the longitudinal axis 20 of the media supply channel 3. This edge 21 can be relatively sharp and represent a separation edge 21. Liquid flowing along the rim 16 (upwards) in the y-direction can be carried along by the gas flow, as already described in connection with Fig. 1 was explained.

[0081] Fig. Figure 4 shows a sectional view (from a first side) of a section of a fuel cell system 1 according to one embodiment of the present disclosure. The embodiment according to Fig. 4 represents a variant of the embodiment according to Fig. 3. In the embodiment according to Fig. In this example, the first surface 14, and in particular the area 18 furthest from the side wall 13, is not horizontal but inclined. The normal vector 17a, which is perpendicular to the first surface 14, therefore does not point in a direction parallel to the longitudinal axis 20 of the media supply channel 3, but forms an angle other than 0° with this longitudinal axis 20. The second surface 15, on the other hand, is horizontal in this example, i.e., it runs perpendicular to the longitudinal axis 20 of the media supply channel 3. The normal vector 17b, which is perpendicular to the second surface 15, therefore points in a direction parallel to the longitudinal axis 20 of the media supply channel 3. The first surface 14 and the second surface 15 converge on a common edge 21, which in turn can represent a tear-off edge 21.

[0082] While the second area 15 in Fig. 3. Two sections 15a and 15b running in different planes; the second surface 15 runs in Fig. 4 in a single plane. Nevertheless, here too, an area adjacent to the side wall can be considered the first section 15a, and a subsequent area, located further to the right, can be considered the second section 15b.

[0083] Due to the inclination of the first surface 14, liquid 5 may be accelerated to the right towards the center of the media supply channel 3 by the gas flow 7, which generally acts upwards, which may contribute to the separation of the liquid 5 at the separation edge 21 and may support the distribution of the liquid 5 in the form of liquid droplets 6 onto several membrane electrode units 2.

[0084] Fig. Figure 5 shows a sectional view (from a first side) of a section of a fuel cell system 1 according to one embodiment of the present disclosure. The embodiment according to Fig. 5 can be considered a variant of the design according to Fig. 3 are considered, but they also have a characteristic from Fig. 4 takes up. The first area 14 of the in Fig. Structure 4, shown in Figure 5, is again similar to that in Figure 5. Fig. 4 - inclined. The second surface 15 and the outer edge 16 resemble those from Fig. 3. However, the second area is 15 of the Fig. 5 is provided with an undercut 19. This means that, starting from the tear-off edge 21, the second surface 15 initially runs against the direction of gas flow 7. After the lowest point of the undercut 19, the second surface 15 then rises towards the side wall 13, approximately as shown in Fig. 3.

[0085] The undercut 19 allows the tear-off edge 21 to be made even sharper than in Fig. 3 is the case. While the second surface 15 and the outer edge 16 in the cross-section of the Fig. 3 form a right angle, these form in Fig. 5 an acute angle. This can also promote the tearing off of the liquid 5 and the distribution of the liquid droplets 6 onto several membrane electrode units 2.

[0086] Fig. Figure 6 shows a diagram illustrating an angle of inclination α. ​​The angle of inclination α is enclosed between a normal vector 17a on the first surface 14 and the longitudinal axis 20 of the media supply channel 3. The angle α thus also indicates the inclination of the first surface 14, or the area 18 furthest from the side wall 13, relative to a horizontal surface or a plane in the xz direction. The angle α can, for example, be between 0° and 70°. A corresponding angle could be determined or illustrated in a similar manner for the second surface 15 (or its first and second sections 15a, 15b) relative to a plane in the xz direction.

[0087] Fig. Figure 7 shows a sectional view (of a first side) of a section of a fuel cell system 1 according to an embodiment of the present disclosure. Fig. 7 shows the same embodiment as Fig. 5. However, in Fig. 7 some reference symbols that are in Fig. The five points shown have been omitted and others added instead. Four points p1 to p4 are in Fig. 7 indicated. A first point p1 on the first surface 14 is located further from the side wall 13 than a second point p2 on the first surface 14. The first point p1 is located further downstream in the flow direction 7 of the gas stream than the second point p2. This also illustrates the inclination of the first surface 14, which may cause liquid 5, which accumulates on the first surface 14, to be transported towards the center of the media supply channel 3 or towards the edge 16 or the separation edge 21, and may experience acceleration into the gas stream.

[0088] Point p3 lies on a line where the second surface 15 abuts the side wall 13. Point p3 is therefore part of the first section 15a of the second surface 15. Point p4 lies at the point on the second surface 15 furthest from the side wall 13. Point p4 is therefore part of the second section 15b of the second surface 15. Point p3 lies further downstream than point p4. This means that the second surface 15 is inclined, at least to some extent, such that fluid falling downwards onto the second surface 15 due to gravity is directed away from the side wall 13. The first section 15a of the second surface 15 is thus designed to direct fluid on the second surface 15 from the side wall 13 to the second section 15b of the second surface 15.However, (part of) the liquid that falls onto the second surface 15, for example, approximately in the middle of the second surface 15 or near the side wall 13, can collect in the undercut 19. To minimize such liquid accumulation, the undercut 19 can be relatively small, i.e., (significantly) smaller than, for example, the remaining part of the second surface 15.

[0089] While the second area 15 in Fig. 7, in particular its first section 15a, has an inclination relative to an xz-plane, which contributes to the flow of liquid on the second surface 15 from the side wall 13 to the second section 15b of the second surface 15, such flow of liquid from the side wall 13 to the second section 15b of the second surface 15 can also occur in the embodiment of the Fig. 4 is possible, where the second surface 15 lies in an xz-plane. This is because, at least from a certain degree of liquid filling on the surface in Fig. 4 horizontal second surface 15, liquid is directed from the first section 15a or from the side wall 13 to the second section 15b of the second surface 15 located further to the right.

[0090] Fig. Figure 8 shows a sectional view (of a first side) of a section of a fuel cell system 1 according to an embodiment of the present disclosure. In this embodiment, the first surface 14 of the structure 4 is inclined such that a first point p1, which is located at a greater distance from the side wall 13 than a second point p2, is further upstream than the second point p2. As in Fig. As shown in Figure 8, a channel 22 forms between the inclined first surface 14 of the structure 4 and the side wall 13 of the lower end plate 9. Liquid 5 that condenses on the first surface 14 or runs upwards along the side wall 13 below the structure 4 (for example, due to the gas flow) is therefore not likely to be transported by the gas flow 7 in one direction towards the center of the media supply channel 3, but rather initially remains in the channel 22. In this embodiment, the second surface 15 of the structure 4 can run parallel to the first surface 14 or form a non-zero angle with it.

[0091] Fig. Figure 9 shows a sectional view (from above) of a section of a fuel cell system 1 according to an embodiment of the present disclosure, for example the embodiment according to Fig. 8. As in Fig. As shown in Figure 9, the structure 4 extends from the side wall 13 towards the center of the media supply channel 3, but not over the entire depth 12 in the x-direction of the media supply channel 3. The structure 4 also does not extend over the entire width 11 in the z-direction of the media supply channel 3, but leaves a lateral opening 23 free. Fig. 9 is this opening between structure 4 and the one in Fig. The opening 23 is located in the section of the side wall of the media supply channel 3 shown above. The opening 23 could also be located between the structure 4 and the section shown above. Fig. The opening 23 could be arranged in the section of the side wall of the media supply channel 3 shown below. In another variant, the opening 23 could also divide the structure 4 into two sections, i.e., be arranged within the structure 4. It would also be conceivable that several openings 23 are provided.

[0092] Liquid 5 can flow out of the channel 22 through the opening 23. The liquid 5 will mainly flow directly along the side wall 13 – this is due to the slope of the first surface 14 (see figure). Fig. 8) In this embodiment, the liquid 5 is intended to reach sidewall sections downstream of the structure 4 directly. This will be explained in more detail below. Fig. 11 explained.

[0093] Fig. Figure 10 shows a sectional view (from above) of a section of a fuel cell system 1 according to an embodiment of the present disclosure. This embodiment can be considered a variant of the embodiment according to Fig. 9 can be viewed, but opening 23 according to Fig. 10 is only formed in a partial area (directly) on the side wall 13. In an area further away from the side wall 13, the structure 4 extends over the entire width 11 of the media supply channel 3. The smaller opening 23 of the embodiment according to Fig. 10 can help to ensure that liquid 5 is removed from the channel 22 ( Fig. 8) to the in Fig. 10, the side wall shown on the left is led to 13.

[0094] Fig. Figure 11 shows a sectional view (from a second side) of a section of a fuel cell system 1 according to an embodiment of the present disclosure, for example the embodiment according to Fig. 8 and Fig. 9. Top right in Fig. Figure 11 shows the corresponding coordinate system, which is aligned with the one in Fig. The coordinate system shown in 1 is consistent. Fig. Figure 11 shows a section 13 of the side wall of the media supply channel 3. Structure 4 is arranged on this section 13 of the side wall. Four membrane electrode units 2a to 2d are indicated above structure 4. The view of structure 4 is shown according to Fig. Only the second surface 15 and the edge 16 furthest from the side wall 13 are visible. The channel 22 is concealed by the second surface 15.

[0095] Structure 4, or rather its first surface 14, which is in Fig. 11 is not visible, is not only as inclined as it appears in Fig. 8 is indicated, but also in such a way that this is in Fig. The end of structure 11 shown on the right is located 4 further upstream (more downstream) than the one in Fig. 11. End shown on the left. Liquid 5 that has accumulated in the channel 22 - for example, after this liquid 5 has, as in Fig. 11, indicated on the side wall 13, has moved upwards - is thus moved by the gas flow in the direction of the opening 23 in order to flow through it out of the channel 22.

[0096] The in Fig. The indicated inclination of structure 4 is not mandatory. The liquid 5 can be used without the inclination shown in Fig. 11. The indicated inclination also results from the fact that the channel 22 is filled to a certain degree with liquid 5, allowing the liquid to drain out of the channel 22 through the opening 23.

[0097] If the fuel cell system 1 is designed such that the gas flow 7 predominantly or under most operating conditions has a rotation about the longitudinal axis 20 of the media supply channel 3, the opening 23 is preferably arranged at a location such that the liquid 5 in the channel 22 is transported in the direction of this opening 23 by the rotation of the gas flow.

[0098] In Fig. The liquid 5 flowing out of or through opening 23 is indicated by a dotted line above structure 4. The width between this dotted line and the right edge of the media supply channel 3 indicates the amount of liquid 5 moving upwards in the media supply channel 3. The entire liquid flow 5 initially arrives at the first membrane electrode assembly 2a. However, because this liquid flow 5 is concentrated in a small area, it cannot be completely absorbed by the first membrane electrode assembly 2a and therefore cannot flood it. Instead, a large portion of the liquid flow 5 is passed on to the second membrane electrode assembly 2b. The amount of liquid 5 arriving there has already decreased somewhat because some of it remained in or on the first membrane electrode assembly 2a.The second membrane electrode unit 2b also cannot completely absorb the incoming liquid flow 5 and passes a large portion of it on to the third membrane electrode unit 2c. Similarly, a large portion of the liquid flow 5 arriving at the third membrane electrode unit 2c is passed on to the fourth membrane electrode unit 2d, and so on. In this way, the amount of liquid flowing through the opening 23 is distributed among several membrane electrode units 2.

[0099] Fig. Figure 12 shows a sectional view (from above) of a section of a fuel cell system 1 according to an embodiment of the present disclosure. This can be considered a modification of the embodiment according to Fig. 2 can be viewed. Fig. Figure 12 primarily serves to illustrate what can be considered the area 18 of structure 4 furthest from the side wall 13.

[0100] Starting from side wall 13 on the left edge of the Fig. 12, the structure 4 extends to the right, in a direction towards the center of the media supply channel 3, i.e., away from the side wall 13. The structure initially extends across the entire width 11 in the z-direction of the media supply channel 3. In a Fig. In the area shown 12 further to the right, the structure 4 no longer extends over the entire width 11 in the z-direction of the media supply channel 3, but only has small additional sections 24 on opposite sides, which are in Fig.The 12 sections are shown as triangular shapes. These extend in the z-direction, however, only over a relatively small area (actually two areas), in particular an area that occupies less than 50% of the width 11 of the media supply channel 3 (in the z-direction). These additional sections 24 are therefore not to be considered when determining the area of ​​the structure 4 or the first surface 14 furthest from the side wall 13. For this purpose, only the central, larger area is to be used, which is therefore designated with the reference numeral 18.

[0101] Further embodiments are listed clearly below: 1. Fuel cell system (1), comprising: a fuel cell stack comprising a plurality of membrane electrode assemblies (2); a media supply channel (3) for supplying gas from an inlet side to the membrane electrode assemblies (2); and a structure (4) arranged on a side wall (13) of the media supply channel (3) and projecting into the media supply channel (3), wherein an extent of the structure (4) in a direction (x) perpendicular to the side wall (13) of the media supply channel (3) is between inclusive of 5% and inclusive of 50% of a width (12) of the media supply channel (3) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3), wherein the media supply channel (3) has a longitudinal axis (20) along which the gas can flow to the individual membrane electrode units (2), wherein the structure (4) has a first surface (14) on its inflow side, wherein a normal vector (17) on the first surface (14) in a first region (18) of the structure (4) which is furthest from the side wall (13) is inclined to the longitudinal axis (20) of the media supply channel (3) by an angle α, the angle α being between inclusive 0° and inclusive 60°. 2. Fuel cell system (1) according to embodiment 1, wherein the extent of the structure (4) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3) is at least 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% and / or at most 45%, 40%, 35%, 30%, 25%, 20%, 15% or 10% of the width (12) of the media supply channel (3) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3). 3. Fuel cell system (1) according to embodiment 1 or 2, wherein the angle α is at most 50°, 40°, 30°, 25°, 20°, 15°, 10° or 5°. 4. Fuel cell system (1) according to one of the preceding embodiments, wherein the structure (4) is arranged further upstream in the flow direction (7) of the gas in the media supply channel (3) than all membrane electrode assemblies (2) of the fuel cell system (1). 5. Fuel cell system (1) according to one of the preceding embodiments, wherein the first region (18), with respect to the extent of the structure (4) in a direction (x) perpendicular to the side wall (13) of the media supply channel (3), is located in a region which is at a distance from the side wall of 50% to 100% of this extent. 6. Fuel cell system (1) according to one of the preceding embodiments, wherein the first surface (14), in particular in the first region (18), is inclined such that a first point (p1) on the first surface (14), in particular located in the first region (18), which is at a greater distance to the side wall (13) than a second point (p2) on the first surface (14), in particular located in the first region (18), is further downstream in the direction of flow (7) of the gas in the media supply channel (3) than the second point (p2). 7. Fuel cell system (1) according to embodiment 6, wherein the structure (4) has a second surface (15) on its downstream side, wherein one or more or all points (p3) of a line along which the second surface (15) borders the side wall (13) are located further downstream than one or more or all points (p4) of the second surface (15) at its edge (16) furthest from the side wall (13). 8. Fuel cell system (1) according to one of the preceding embodiments, wherein the structure (4) extends over the entire width (11) of the media supply channel (3) in a direction (z) along the side wall (13). 9. Fuel cell system (1) according to one of the preceding embodiments, wherein the structure (4) has a tear-off edge (21) on its side (16) facing away from the side wall (13). 10. Fuel cell system (1) according to embodiment 9, wherein the separation edge (21) is arranged in the first region (18). 11. Fuel cell system (1) according to one of embodiments 1 to 5, wherein the first surface (14), in particular in the first region (18), is inclined such that a first point (p1) on the first surface (14), in particular located in the first region (18), which is at a greater distance to the side wall (13) than a second point (p2) on the first surface (14), in particular located in the first region (18), is located further upstream in the direction of flow (7) of the gas in the media supply channel (3) than the second point (p2). 12. Fuel cell system (1) according to embodiment 11, wherein the structure (4) in a second area adjacent to the side wall (13) occupies less than the entire width (11) of the media supply channel (3) in a direction (z) along the side wall (13). 13. Fuel cell system (1) according to embodiment 12, wherein, due to the smaller width of the structure (4) in the second area compared to the width (11) of the media supply channel (3), an opening (23) is created through which liquid (5), which accumulates on the first surface (14) during operation of the fuel cell system (1), can flow downstream in the direction of gas flow (7) towards the membrane electrode units (2). 14. Fuel cell system (1), comprising: a fuel cell stack comprising a plurality of membrane electrode assemblies (2); a media supply channel (3) for supplying gas from an inlet side to the membrane electrode assemblies (2); and a structure (4) arranged on a side wall (13) of the media supply channel (3) and projecting into the media supply channel (3), wherein an extent of the structure (4) in a direction (x) perpendicular to the side wall (13) of the media supply channel (3) is between inclusive of 5% and inclusive of 50% of a width (12) of the media supply channel (3) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3), wherein the media supply channel (3) has a longitudinal axis (20) along which the gas can flow to the individual membrane electrode units (2), wherein the structure (4) has a first surface (14) on its inflow side and a second surface (15) on its outflow side, wherein a majority of the normal vectors on the second surface (15), which have a component in the direction of the flow direction of the gas along the longitudinal axis (20), are either aligned parallel to the longitudinal axis (20) or have a component pointing towards the center of the media supply channel (3). 15. Fuel cell system (1), comprising: a fuel cell stack comprising a plurality of membrane electrode assemblies (2); a media supply channel (3) for supplying gas from an inlet side to the membrane electrode assemblies (2); and a structure (4) arranged on a side wall (13) of the media supply channel (3) and projecting into the media supply channel (3), wherein an extent of the structure (4) in a direction (x) perpendicular to the side wall (13) of the media supply channel (3) is between inclusive of 5% and inclusive of 50% of a width (12) of the media supply channel (3) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3), wherein the media supply channel (3) has a longitudinal axis (20) along which the gas can flow to the individual membrane electrode units (2), wherein the structure (4) has a first surface (14) on its inflow side and a second surface (15) on its outflow side, wherein one or more or all points (p3) of a line along which the second surface (15) borders the side wall (13), - lie further downstream than one or more or all points (p4) of the second surface (15) at its edge (16) furthest from the side wall (13), or - lie at the same height in the direction of flow as one or more or all points (p4) of the second surface (15) at its edge (16) furthest from the side wall (13).

[0102] While at least one exemplary embodiment has been described above, it should be noted that a large number of variations exist. It should also be noted that the described exemplary embodiments are merely non-limiting examples, and it is not intended to restrict the scope, applicability, or configuration of the devices and methods described herein. Rather, the preceding description will provide guidance for those skilled in the art in implementing at least one exemplary embodiment. It is understood that various modifications to the function and arrangement of the elements described in an exemplary embodiment can be made without derogating from the subject matter defined in the appended claims and their legal equivalents.The features described herein may be combined with one another in any way, unless expressly excluded or technically impossible. Likewise, features described primarily in connection with one aspect disclosed herein may also represent features of the other aspects disclosed herein. Furthermore, all aspects and features disclosed herein, either individually or in combination, are to be considered aspects of the present invention. Reference symbol list 1 Fuel cell system 2(ad) Membrane electrode unit(s) 3 Media feed channel 4 Structure 5 Liquid 6 drops of liquid 7 (Direction of flow of the) gas stream(s) 8 upper end plate 9 lower end plate 10 Media distribution panel 11 Width of the media supply channel 12 Depth of the media supply channel 13 Side wall of the media supply channel 14 first area 15 second area 15a first section of the second area 15b second section of the second area 16 Edge furthest from the side wall 17a,b Normal vector 18 Main section of the edge of the structure 19 Undercut 20 Longitudinal axis of the media supply channel 21 Tear-off edge 22 gutter 23 Opening 24 additional sections of the structure p1-p4 points α Angle of inclination x Depth direction y Altitude direction z Latitude direction

Claims

[1] Fuel cell system (1) comprising: a fuel cell stack comprising a plurality of membrane electrode assemblies (2); a media supply channel (3) for supplying gas from an inlet side to the membrane electrode assemblies (2); and a structure (4) which is arranged on a side wall (13) of the media supply channel (3) and projects into the media supply channel (3), wherein the extension of the structure (4) in a direction (x) perpendicular to the side wall (13) of the media supply channel (3) is between inclusive of 5% and inclusive of 50% of a width (12) of the media supply channel (3) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3), or wherein the structure (4) occupies between inclusive of 5% and inclusive of 50% of the flow cross-section of the media supply channel (3); wherein the media supply channel (3) has a longitudinal axis (20) along which the gas can flow to the individual membrane electrode units (2), wherein the structure (4) has a first surface (14) on its inflow side and a second surface (15) on its outflow side, wherein the structure (4) is arranged further upstream in the direction of flow (7) of the gas in the media supply channel (3) than all membrane electrode units (2) of the fuel cell system (1), wherein one or more or all points (p3) of a line along which the second surface (15) borders the side wall (13) are located further downstream than one or more or all points (p4) of the second surface (15) at its edge (16) furthest from the side wall (13), wherein the second surface (15) has a first section (15a) adjoining the side wall (13) and a second section (15b) adjoining the first section (15a) and being further away from the side wall (13) than the first section (15a), wherein the first section (15a) of the second surface (15) is designed such that liquid on the second surface (15) is directed from the side wall (13) to the second section (15b) of the second surface (15). [2] Fuel cell system (1) according to claim 1, wherein the extent of the structure (4) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3) is at least 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% and / or at most 45%, 40%, 35%, 30%, 25%, 20%, 15% or 10% of the width (12) of the media supply channel (3) in the direction (x) perpendicular to the side wall (13) of the media supply channel (3), or wherein the structure (4) is at least 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% and / or at most 45%, 40%, 35%, 30%, 25%, occupies 20%, 15% or 10% of the flow cross-section of the media supply channel (3). [3] Fuel cell system (1) according to one of the preceding claims, wherein a majority of normal vectors (17b) on the second surface (15), which have a component in the direction of the flow direction (7) of the gas along the longitudinal axis (20), are either aligned parallel to the longitudinal axis (20) or have a component that points towards the center of the media supply channel (3). [4] Fuel cell system (1) according to one of the preceding claims, wherein the structure (4) has a tear-off edge (21) on its side (16) facing away from the side wall (13). [5] Fuel cell system (1) according to one of the preceding claims, wherein the second surface (15) has an undercut (19) in its second section (15b). [6] Fuel cell system (1) according to one of the preceding claims, wherein the structure (4) has a first region (18) that is furthest away from the side wall (13) and a second region (25) that is adjacent to the side wall (13). [7] Fuel cell system (1) according to one of the preceding claims, wherein the structure (4), in particular in the first region (18) and / or in the second region (25), extends over the entire width (11) of the media supply channel (3) in a direction (z) along the side wall (13). [8] Fuel cell system (1) according to any one of claims 1 to 6, wherein the structure (4), in particular in the second region (25), occupies less than the entire width (11) of the media supply channel (3) in one direction (z) along the side wall (13). [9] Fuel cell system (1) according to claim 8, wherein, due to the smaller width of the structure (4) in the second area (25) compared to the width (11) of the media supply channel (3), an opening (23) is created through which the liquid (5), which accumulates on the first surface (14) during operation of the fuel cell system (1), can flow downstream in the direction of flow (7) of the gas towards the membrane electrode assemblies (2). [10] Fuel cell system (1) according to one of the preceding claims, wherein the first surface (14), in particular in the first region (18), is inclined such that a first point (p1) on the first surface (14), in particular located in the first region (18), which is at a greater distance to the side wall (13) than a second point (p2) on the first surface (14), in particular located in the first region (18), is located further upstream in the flow direction (7) of the gas in the media supply channel (3) than the second point (p2), or wherein the first surface (14), in particular in the first region (18), is inclined such that a first point (p1) on the first surface (14), in particular located in the first region (18), which is at a greater distance to the side wall (13) than a second point (p2) on the first surface (14), in particular located in the first region (18),in the direction of gas flow (7) in the media supply channel (3) lies further downstream than the second point (p2). [11] Fuel cell system (1) according to claim 6 or according to any one of claims 7 to 10 directly or indirectly dependent on claim 6, wherein a normal vector (17a) on the first surface (14) in the first region (18) of the structure (4) is inclined at an angle α to the longitudinal axis (20) of the media supply channel (3), wherein the angle α is between inclusive 0° and inclusive 60°, in particular wherein the angle α is at most 50°, 40°, 30°, 25°, 20°, 15°, 10° or 5°. [12] Fuel cell system (1) according to claim 6 or according to any one of claims 7 to 11 directly or indirectly dependent on claim 6, wherein the first region (18), with respect to the extent of the structure (4) in a direction (x) perpendicular to the side wall (13) of the media supply channel (3), is located in a region which is at a distance from the side wall of 50% to 100% of this extent. [13] Fuel cell system (1) comprising: a fuel cell stack comprising a plurality of membrane electrode assemblies (2); a media supply channel (3) for supplying gas from an inlet side to the membrane electrode assemblies (2); and a structure (4) which is arranged on a side wall (13) of the media supply channel (13) and projects into the media supply channel (3), wherein the structure (4) is arranged further upstream in the direction of flow (7) of the gas in the media supply channel (3) than all membrane electrode units (2) of the fuel cell system (1), wherein the structure (4) has a first surface (14) on its inflow side and a second surface (15) on its outflow side, wherein the first surface (14) has a border configured such that liquid (5) which accumulates on the first surface (14) during operation of the fuel cell system (1) is supplied to the gas flow (7) in the media supply channel (3) and / or is distributed to the plurality of membrane electrode assemblies (2), and wherein one or more or all points (p3) of a line along which the second surface (15) borders the side wall (13) are further downstream than one or more or all points (p4) of the second surface (15) at its edge (16) furthest from the side wall (13). [14] Method for using a fuel cell system (1) according to one of the preceding claims, wherein both gas in the media supply channel (3) and liquid (5) which accumulates on the first surface (14) during operation of the fuel cell system (1) is enabled to reach the membrane electrode units (2).

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