Humidification device for a fuel cell system

Abstract

Humidification device for a fuel cell system (12) of a motor vehicle, which has a number of fuel cell stacks (14a, 14b), wherein the humidification device (10) has a humidification housing (11) and a main channel (1), which is divided at a transition point (30) into a number of secondary channels (2a, 2b) corresponding to the number of fuel cell stacks (14a, 14b), wherein at least one flap (3) is arranged at the transition point (30), wherein in each case a secondary channel (2a, 2b) merges into a humidification module (4a, 4b) arranged in the humidification housing (11), wherein in each case a humidification module (4a, 4b) merges into an outlet channel (5a, 5b), which opens into a respective fuel cell housing (18a, 18b), in which in each case a fuel cell stack (14a, 14b) is arranged wherein, during operation of the humidifying device (10), a flow of dry air is to be supplied via the main duct (1),by adjusting a position of the at least one flap (3) and dividing it into a number of partial flows corresponding to the number of secondary channels (2a, 2b), wherein a partial flow is to be fed to a respective secondary channel (2a, 2b), wherein the respective partial flow is to be humidified via a respective humidification module (4a, 4b) and fed to a respective fuel cell stack (14a, 14b), wherein at least one adjustable diaphragm is arranged along at least one secondary channel (2a, 2b) and / or outlet channel (5a, 5b), via which a cross-sectional area of the respective secondary channel (2a, 2b) and / or outlet channel (5a, 5b) is to be regulated.

Description

[0001] The invention relates to a humidification device for a fuel cell system, a fuel cell system and a method for operating a fuel cell system.

[0002] A fuel cell system for powering a motor vehicle has a stack of fuel cells and an output of approximately 100 kW. Thus, components of the fuel cell system are designed exclusively for this single stack. However, buses for transporting passengers, for example, may have multiple stacks of fuel cells. In these systems, each subsystem is assigned to a stack and is designed and constructed identically.

[0003] A fuel cell system intended for stationary application can also have several stacks of fuel cells, but humidification intended for this purpose is not suitable for automotive purposes.

[0004] A fuel cell system known from DE 11 2004 001 832 B4 comprises at least two fuel cell stacks configured to receive supplied reaction gases comprising an oxidizing gas and a fuel gas to generate electricity through an electrochemical reaction, a humidifier configured to humidify reaction gases for the at least one fuel cell stack, and a reaction gas supply pipe configured to conduct the reaction gas from a reaction gas outlet opening of the humidifier to reaction gas supply openings of two of the fuel cell stacks. Furthermore, the fuel cell system comprises a reaction gas outlet pipe configured to discharge the reaction gas from reaction gas outlet openings of the two fuel cell stacks.The reaction gas supply pipe is branched at a branching point into two sections, each directed toward the two fuel cell stacks, wherein lengths of sections from the branching point to the reaction gas supply openings of the two fuel cell stacks are equal.

[0005] A flow-switching fuel cell system with two fuel cell stacks is known from DE 10 2008 033 472 B4 and comprises a water vapor transfer device connected to a fluid outlet. The water vapor transfer device is arranged in a cathode flow path and comprises two flow paths. A first flow path is connected to respective cathode outlets of the fuel cell stacks and the fluid outlet. A second flow path is connected to respective cathode inlets of the fuel cell stacks and a fluid source for supplying a fluid.

[0006] A high-temperature fuel cell with a gold seal is known from US Pat. No. 7,727,661 B2 and comprises several circularly arranged fuel cell stacks with a common heat exchanger. This provides for the distribution of supply air to the various fuel cell stacks, as well as combined connections for the supply air, exhaust air, and fuel gas.

[0007] A humidifier for a fuel cell presented in the document DE 101 02 358 B4 comprises a humidification housing for accommodating a plurality of bundles of water-permeable hollow fiber membranes arranged in the longitudinal direction of the humidification housing in order to exchange different water contents of two different gases which are to be conducted inside and outside the water-permeable hollow fiber membranes and to humidify the gas which has the lower water content.

[0008] A humidification device for a fuel cell system of a motor vehicle can also be found in the documents JP 2006-114415 A, US 2009 / 0317676 A1, DE 11 2004 001 832 T5 and US 2008 / 0093752 A1.

[0009] Against this background, a humidification device, a fuel cell system, and a method having the features of the independent patent claims are presented. Embodiments of the humidification device, the fuel cell system, and the method are set forth in the dependent patent claims.

[0010] The humidification device according to the invention is provided for a fuel cell system of a motor vehicle having a plurality of fuel cell stacks. The humidification device comprises a humidification housing and a main channel, which is divided at a transition point into a number of secondary channels corresponding to the number of fuel cell stacks, with at least one flap being arranged at the transition point. Each secondary channel merges into a humidification module arranged in the humidification housing, with each humidification module merging into an outlet channel, which opens into a fuel cell housing in which a fuel cell stack is arranged.During operation of the humidification system, a flow of dry air is supplied via the main duct, regulated by adjusting the position of at least one flap, and divided into a number of sub-flows corresponding to the number of sub-ducts. Each sub-flow is supplied to a sub-duct, with each sub-flow being humidified via a respective humidification module and fed to a respective fuel cell stack.

[0011] In addition, each fuel cell housing is connected via a gas supply channel to a respective subchamber within the humidification housing, wherein air from the respective fuel cell housing is to be supplied via the respective gas supply channel to the humidification module arranged in the respective subchamber.

[0012] According to the invention, at least one adjustable aperture is optionally arranged along at least one secondary channel and / or outlet channel, via which a cross-sectional area of ​​the respective secondary channel and / or outlet channel can be regulated. Furthermore, at least one adjustable aperture can also optionally be arranged along at least one gas outlet channel. By adjusting at least one such optional aperture of a said channel, a flow characteristic and / or a quantity of the flowing air to be conveyed can be influenced by varying the respective cross-sectional area in the channel.

[0013] The fuel cell system comprises a number of k fuel cell stacks, where k is at least two. The common transition point of the humidification device is therefore divided into k secondary channels. At least one flap is arranged at the transition point for the total of k secondary channels.

[0014] Furthermore, to explain an embodiment of the humidification device, a parameter i is introduced which ranges from 1 to k. In this case, an i-th secondary duct of the total of k secondary ducts merges into an i-th humidification module of the total of k humidification modules arranged in the humidification housing. Each i-th humidification module merges into an i-th outlet duct, which opens into an i-th fuel cell housing, in each of which an i-th fuel cell stack is arranged. Thus, a flow of dry air is to be supplied via the main duct, regulated by adjusting a position of the at least one flap, and divided into k partial flows. An i-th partial flow of the total of k partial flows is to be supplied to an i-th secondary duct, wherein the i-th partial flow is to be humidified via an i-th humidification module and supplied to an i-th fuel cell stack.

[0015] Accordingly, an i-th fuel cell housing is connected via an i-th gas supply channel to an i-th subchamber within the humidification housing, wherein humidified air from the i-th fuel cell housing is supplied via the i-th gas supply channel to the i-th humidification module arranged in the i-th subchamber. The i-th partial flow of still dry air flowing through the i-th humidification module is humidified by already humidified air from the i-th fuel cell stack, wherein the already humidified air flows around and / or through the i-th humidification module. Alternatively or additionally, dry air is supplied to the i-th fuel cell stack.

[0016] The humidification housing has at least one outlet funnel through which air is to be discharged from the humidification housing. Furthermore, at least one partition wall can optionally be arranged in the humidification housing, separating the sub-chambers from each other. This makes it possible for each sub-chamber to have its own outlet funnel.

[0017] Accordingly, in addition to the main duct and at least one flap, the humidification system comprises a total of k sub-modules. An i-th sub-module of these k sub-modules has an i-th secondary duct, an i-th humidification module, and an i-th outlet duct, through which an i-th partial air flow for an i-th fuel cell stack is to be directed. Further optional components of the i-th sub-module include, among others, the i-th gas supply duct, the i-th partial chamber, and the i-th outlet duct.

[0018] The fuel cell system according to the invention for a motor vehicle comprises a plurality of fuel cell stacks, each of which is arranged in a fuel cell housing. The fuel cell system also comprises a humidification device.

[0019] The method according to the invention is to be used for operating a fuel cell system having a plurality of fuel cell stacks, each fuel cell stack being arranged in a fuel cell housing, and having a humidification device. The humidification device has a humidification housing and a main channel which is divided at a transition point into a number of secondary channels corresponding to the number of fuel cell stacks, at least one flap being arranged at the transition point, each secondary channel merging into a humidification module arranged in the humidification housing, each humidification module merging into an outlet channel which opens into a fuel cell housing in which a fuel cell stack is arranged.In the method, a stream of dry air is supplied via the main duct, regulated by adjusting the position of at least one flap, and divided into a number of substreams corresponding to the number of subducts, with each substream being supplied to a subduct. Furthermore, each substream is humidified via a respective humidification module and supplied to a respective fuel cell stack.

[0020] Each fuel cell housing is connected to a subchamber within the humidification housing via a gas supply channel. In this process, air from the respective fuel cell housing is supplied to the humidification module located in the respective subchamber via the respective gas supply channel.

[0021] A cross-sectional area of ​​at least one secondary channel and / or outlet channel is regulated with at least one adjustable optional aperture arranged along the at least one secondary channel and / or outlet channel.

[0022] In a further embodiment, air is discharged from the humidification housing via at least one outlet funnel, with humidified air being supplied to the humidification module arranged in the respective subchamber. Humidified air is guided around the humidification module arranged in the respective subchamber and / or through the humidification module arranged in the respective subchamber. Furthermore, it is possible for dry air to be guided around the humidification module arranged in the respective subchamber instead of moist air.

[0023] In the proposed method for operating a fuel cell system, the position of at least one flap is adjusted. The flow of dry air from the main duct is divided into sub-flows, with each sub-flow being fed to a respective secondary duct, humidified by a respective humidification module, and then fed to the respective fuel cell stack.

[0024] In addition, the partial flow of already humidified air flowing within the respective humidification module in the direction of the respective fuel cell stack, which is provided to the respective humidification module from the fuel cell stack and flows around and / or through the respective humidification module, is humidified.

[0025] In addition, air is discharged from the humidification housing via at least one outlet funnel. If each subchamber, where all subchambers are separate from each other, is assigned an outlet funnel, air from each subchamber is discharged via a separate outlet funnel.

[0026] When carrying out the method, the flow of dry air provided via the main duct is divided into sub-flows, and each sub-flow is humidified in a respective humidification module. The humidified air is fed to a respective fuel cell stack. Air from each fuel cell stack is fed back to the respective humidification module and used to humidify the dry air flowing from the main duct through the respective humidification module. The quantity and / or flow velocity of air flowing through each secondary duct is regulated by the at least one flap and / or the at least one optional aperture arranged along the at least one secondary duct and / or outlet duct.

[0027] The humidification device described is suitable for the presented fuel cell system, which comprises two or more or k stacks of fuel cells. The humidification device comprises at least two tubular humidification modules operated in countercurrent. In alternative embodiments, the humidification device has at least two tubular humidification modules operated in crosscurrent or cocurrent. The dry i-th partial flow of air flowing through the i-th humidification module is humidified by an i-th partial flow of already humidified air from the i-th fuel cell stack, which flows around the i-th humidification module and / or through the i-th humidification module in a direction opposite to the direction of the i-th partial flow. Furthermore, the humidification device can be designed as a plate-based device.

[0028] The use of the humidification device enables, among other things, the safe operation of a so-called PEM fuel cell system. The PEM fuel cell system has at least one membrane, designed, for example, as a proton exchange membrane or proton exchange membrane (PEM), as part of a fuel cell, through which only protons can be transported, whereas such a proton exchange membrane is impermeable to gases, in the case of application for the fuel cell system usually oxygen and hydrogen. To operate the at least one membrane, designed, for example, as a proton exchange membrane, a correct degree or value for humidity must be maintained in the fuel cell system. A precisely adjustable degree for humidity usually depends on a design and thus a shape of the fuel cells and / or a material from which the membranes in the fuel cells are made.

[0029] In the automotive application of the fuel cell system envisaged here, the moisture is typically transferred from a moist cathodic exhaust gas to the dry, cathodic fresh gas using, for example, a tubular membrane as a humidification module, which is semi-permeable to water and / or water vapor. The humidified cathodic fresh gas typically has a dew point that is significantly above ambient temperature. In this case, a short distance between an outlet of the humidification device and an inlet to the respective fuel cell housings, in which the respective fuel cell stacks are arranged, must be provided for the fuel cell system, and the fuel cell system must be designed compactly and provided cost-effectively.

[0030] Here, it is provided that a flow of dry cathodic fresh gas is supplied as dry fresh air via the main duct and at the transition point is divided into a total of k partial flows via the flaps arranged therein, fed via the i-th secondary duct to the i-th humidification duct, humidified therein and fed via the i-th outlet duct to the i-th fuel cell stack. The now humidified cathodic fresh gas is converted into moist cathodic exhaust gas as used air in a reaction carried out by the i-th fuel cell stack and is fed back to the i-th humidification module via the i-th gas supply duct, whereby the moist cathodic exhaust gas is used to humidify new cathodic fresh gas, which is conveyed via the i-th secondary duct to the i-th humidification module. Accordingly, the originally supplied dry air ordry cathodic fresh gas is humidified in the i-th humidification module by used, humid air or humid cathodic exhaust gas supplied to the i-th humidification module from the i-th fuel cell stack.

[0031] In a fuel cell system with a multi-stack concept, a humidification module is assigned to each fuel cell stack. Furthermore, a uniform, undivided stream of humidified air is provided from each humidification module for each fuel cell stack. This avoids the splitting of a humidified partial air stream from the humidification module into individual feed devices from a humidification module. At operating points where lines for transporting humid air are cold, e.g., after the fuel cell system has started up or after a prolonged low-load phase followed by a full-load phase, the effects of condensation of humidification water, which could impair the operation of the fuel cell system, can be reduced.

[0032] The humidification device can be used for a motor vehicle, i.e. for a passenger and / or commercial vehicle and thus also for a bus or omnibus for passenger transport, which comprises the fuel cell system with several fuel cell stacks, wherein an integration of components to be used is possible with the humidification device and / or the fuel cell system.

[0033] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0034] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0035] The invention is illustrated schematically in the drawing using embodiments and is described schematically and in detail with reference to the drawing. Fig. 1 shows a schematic representation of an embodiment of a humidification device according to the invention for an embodiment of a fuel cell system according to the invention.

[0036] The Fig. The embodiment of the humidification device 10 shown schematically in Figure 1 is designed as a component of the embodiment of the fuel cell system 12, which here has several, namely two, fuel cell stacks 14a, 14b, wherein each fuel cell stack 14a, 14b is arranged in a fuel cell housing 18a, 18b provided for it.

[0037] The humidification device 10 here comprises a humidification housing 11 and a main duct 1 or main branch, which branches into a first secondary duct 2a and a second secondary duct 2b, whereby these secondary ducts 2a, 2b can also be referred to as secondary branches. A flap 3 mounted on one side is arranged in a transition point 30 as a branch, via which the main duct 1 is divided into the secondary ducts 2a, 2b. This flap 3 is arranged here at the transition point 30 of a common inner wall of the two secondary ducts 2a, 2b between the two secondary ducts 2a, 2b, whereby the transition point 30 is arranged at a boundary between the two secondary ducts 2a, 2b.

[0038] Each secondary channel 2a, 2b transitions into a cylindrical humidification module 4a, 4b, with each humidification module 4a, 4b being designed as a moisture-transferring, tubular membrane. An interface 24a, 24b is arranged at a transition between the respective secondary channel 2a, 2b and the respective humidification module 4a, 4b. The humidification modules 4a, 4b presented here are designed as membrane modules, with each humidification module 4a, 4b comprising a plurality, for example, several hundred, tubes that are connected to one another at the interface 24a, 24b, for example, using epoxy resin.

[0039] In addition, a baffle (not shown) is arranged along each secondary channel 2a, 2b, via which a cross-sectional area of ​​the respective secondary channel 2a, 2b can be individually adjusted for each secondary channel 2a, 2b. Furthermore, each humidification module 4a, 4b transitions into an outlet channel 5a, 5b, wherein the outlet channels 5a, 5b are designed here as outlet bends. Each outlet channel 5a, 5b opens into a fuel cell housing 18a, 18b, in which a fuel cell stack 14a, 14b is arranged.

[0040] The humidification modules 4a, 4b are arranged entirely within the humidification housing 11 of the humidification device 10, whereas the secondary channels 2a, 2a and the outlet channels 5a, 5b are each only partially arranged within the humidification housing 11. In an alternative embodiment, it is possible to fully integrate each secondary channel 2a, 2b and / or outlet channel 5a, 5b into the humidification housing 11, depending on the package and functional requirements.

[0041] The humidification housing 11 is in the Fig.In the embodiment of the humidification device 10 shown in Figure 1, the humidification device 10 is divided into two halves or subchambers 22a, 22b by a partition wall 8, which is arranged along a plane of symmetry of the humidification housing 11 of the humidification device 10. These subchambers are mirror-symmetrical with respect to the plane of symmetry. A humidification module 4a, 4b is arranged in each subchamber 22a, 22b. Furthermore, each fuel cell housing 18a, 18b and each subchamber 22a, 22b is assigned a gas supply channel 6a, 6b, which extends from the respective fuel cell housing 18a, 18b into the respective subchamber 22a, 22b.

[0042] Between the partition wall 8 and a respective humidification module 4a, 4b, an inlet module 7a, 7b or inlet header for the gas supplied or flowing into the respective subchamber 22a, 22b through a respective gas supply channel 6a, 6b is arranged in the respective subchamber 22a, 22b. Furthermore, at least one outlet channel 9, designed here as an outlet funnel and arranged on a wall of a second subchamber 22b, is provided.

[0043] In a possible embodiment, a first sub-chamber 22a can also have an outlet channel on one wall, wherein both outlet channels 9 in this case are arranged mirror-symmetrically to the plane of symmetry. Furthermore, it is conceivable to provide a common outlet channel 9 for both sub-chambers 22a, 22b, which can be arranged and designed symmetrically or mirror-symmetrically to the plane of symmetry. In this case, an opening of the outlet channel 9, through which it opens into the humidification housing 11, is divided by the partition wall 8. In a further alternative embodiment, it is possible for the partition wall 8 to only partially or sectionally separate the humidification housing 11 and to be connected to inlet modules that form a continuation of the partition wall 8.

[0044] Overall, in the embodiment of the fuel cell system 12 and thus of the humidification device 10 presented here, the first fuel cell stack 14a in the first fuel cell housing 18a is assigned a first secondary channel 2b, a first humidification module 4b arranged in a first subchamber 22b, and a first outlet channel 5b. Furthermore, the first fuel cell stack 14a is assigned a first inlet module 7a and a first gas supply channel 6a. Accordingly, the second fuel cell stack 14b in the second fuel cell housing 18b is assigned a second secondary channel 2b, a second humidification module 4b arranged in a second subchamber 22a, and a second outlet channel 5b. Furthermore, the second fuel cell stack 14b is assigned a second inlet module 7b and a second gas supply channel 6b.

[0045] In the embodiment presented here, it is provided that at least the aforementioned components assigned to the first fuel cell stack 14a are designed and arranged symmetrically or mirror-symmetrically with respect to the plane of symmetry through the partition wall 8 to corresponding or similar components assigned to the second fuel cell stack 14b. In detail, the first secondary channel 2a is designed and arranged symmetrically or mirror-symmetrically with respect to the second secondary channel 2b, the first sub-chamber 22a is designed and arranged symmetrically or mirror-symmetrically with respect to the second sub-chamber 22b, the first humidification module 4a is designed and arranged symmetrically or mirror-symmetrically with respect to the second humidification module 4b, the first gas supply channel 6a is designed and arranged symmetrically or mirror-symmetrically with respect to the second gas supply channel 6b, and the first inlet module 7a is symmetrical ordesigned and arranged mirror-symmetrically to the second inlet module 7b. Furthermore, the two subchambers 22a, 22b, i.e., interior spaces each enclosed by a subchamber 22a, 22b, can also be arranged and designed symmetrically or mirror-symmetrically to the plane of symmetry. If, in a further embodiment, a wall of each subchamber 22a, 22b has an outlet channel 9, these can also be arranged and designed symmetrically or mirror-symmetrically.

[0046] The partition wall 8 between the two subchambers 22a, 22b, the flap 3 arranged at the transition point 30, and the main channel 1 are assigned as common components to both fuel cell stacks 14a, 14b. The plane of symmetry runs through a central axis of the main channel 1, which can also be designed as a rotational axis if the main channel 1 is rotationally symmetrical. The plane of symmetry also runs through the transition point 30, where the flap 3 is pivotably arranged. The plane of symmetry also runs through the flap 3, provided that the flap 3 is in a so-called neutral position exactly between the components assigned to the respective fuel cell stacks 14a, 14b.During operation of the humidification device 10, the flap 3 can be pivoted relative to a fastening point at which the flap 3 is arranged at the transition point 30, either in the direction of the components assigned to the first fuel cell stack 14a or in the direction of the components assigned to the second fuel cell stack 14b. For this purpose, a joint, e.g., designed as a hinge, can be provided at the fastening point, via which the flap 3 is fastened at the transition point 30 to a common inner wall of both secondary channels 2a, 2b.

[0047] In a possible alternative embodiment, a fuel cell system having more than two fuel cell stacks can be assigned a further embodiment of a humidification device, wherein each of these fuel cell stacks is assigned the same components as the two fuel cell stacks 14a, 14b of the embodiment of the fuel cell system 12 explicitly presented here. In this case, a humidification housing of the humidification device can be designed to be axially symmetrical with respect to an axis of symmetry and divided into a number of subchambers corresponding to the number of fuel cell stacks, which are separated from one another by partition walls. The components assigned to the respective fuel cell stacks are in this case designed and arranged to be axially symmetrical with respect to the common axis of symmetry.

[0048] By providing symmetry, it is possible for each of the partial flows to flow along identically designed components and to be subjected to the same flow rate by the components. This ensures that each fuel cell stack 14a, 14b is supplied with the same amount of air, with each partial flow having identical flow characteristics, allowing all fuel cell stacks 14a, 14b to operate in a similar manner.

[0049] During operation of the humidification device 10 and the fuel cell system 12, a stream of compressed, dry or non-humidified fresh air is conveyed in a single flow from an upstream component (not shown here), e.g., a compressor, through the main duct 1 to the transition point 30 of the two secondary ducts 2a, 2b, where it is divided into two partial streams. Within the humidification device 10, each incoming partial stream of fresh air is separated or divided into two secondary ducts 2a, 2b.

[0050] To compensate for varying pressure drops across the fuel cell stacks 14a, 14b and / or pipes between the fuel cell stacks 14a, 14b or other air-exposed channels, e.g., pipes, a hydrodynamic cross-section of the secondary channels 2a, 2b is adjusted differently using baffles. Furthermore, it is possible to vary and thus adjust the hydrodynamic cross-sections of other components, e.g., the outlet channels 5a, 5b and / or the gas supply channels 7a, 7b, using baffles arranged therein. The flow of fresh air is also changed by positioning the cantilevered flap 3.

[0051] The partial streams, into which the originally conveyed stream of dry air is divided or separated at the transition point 30, then flow through the tubular humidification modules 4a, 4b, which are designed as moisture-transferring membranes, thereby humidifying the air. The now humidified partial air streams flow over or through the outlet channels 5a, 5b to the fuel cell stacks 14a, 14b. After passing through the active surfaces within the fuel cell stacks 14a, 14b, whereby the air is enriched with water, the now humidified air is fed back to the humidification modules 4a, 4b as exhaust gas from the fuel cell stacks 14a, 14b via the separate gas supply channels 6a, 6b, whereby the humidified air flows around and / or through a respective humidification module 4a, 4b. In this case, a partial flow of humidified air can be supplied either via a counterflow shown here or as a cocurrent or crosscurrent.A specific type of air supply must be designed depending on the situation.

[0052] In the illustrated embodiment, the humidified air flows as exhaust gas separated from the partition wall 8 along and / or through the humidification modules 4a, 4b to be supplied for further processing via the at least one outlet funnel 9. In another embodiment, the humidified air can be combined with the inlet modules 7a, 7b immediately after it has flowed in. Distribution and / or regulation of the air flowing in through the main duct 1 and to be distributed among the secondary ducts 2a, 2b is controlled by adjusting the position of the flap 3, whereby different amounts of air can be supplied to the secondary ducts 2a, 2b, thereby ensuring that the same amount of air is supplied to the fuel cell stacks 14a, 14b at the same time. Additional regulation of the amount of air is achieved by regulating the cross-sectional areas of the secondary ducts 2a, 2b via the baffles.

[0053] In a further embodiment, a respective aperture can be arranged in each outlet channel 5a, 5b and / or in each gas supply channel 6a, 6b, via which aperture a cross-sectional area of ​​the respective outlet channel 5a, 5b and / or gas supply channel 6a, 6b can be regulated and thus the flow characteristics of the air flowing through can be influenced. The setting of the flap 3 and at least one aperture in at least one secondary channel 2a, 2b, an outlet channel 5a, 5b and / or a gas supply channel 6a, 6b can be adjusted depending on a flow characteristic and / or quantity of the air flowing through, wherein a respective flow characteristic is to be determined by sensors not shown in detail. Thus, the same quantity of air with the same flow characteristic can be supplied to each fuel cell stack 14a, 14b at the same time.

Claims

[1] Humidification device for a fuel cell system (12) of a motor vehicle, which has a number of fuel cell stacks (14a, 14b), wherein the humidification device (10) has a humidification housing (11) and a main channel (1) which is divided at a transition point (30) into a number of secondary channels (2a, 2b) corresponding to the number of fuel cell stacks (14a, 14b), wherein at least one flap (3) is arranged at the transition point (30), wherein in each case a secondary channel (2a, 2b) merges into a humidification module (4a, 4b) arranged in the humidification housing (11), wherein in each case a humidification module (4a, 4b) merges into an outlet channel (5a, 5b) which opens into a respective fuel cell housing (18a, 18b) in which in each case a fuel cell stack (14a, 14b), wherein during operation of the humidification device (10) a flow of dry air is supplied via the main duct (1),by adjusting a position of the at least one flap (3) and dividing it into a number of partial flows corresponding to the number of secondary channels (2a, 2b), wherein a partial flow is to be fed to a respective secondary channel (2a, 2b), wherein the respective partial flow is to be humidified via a respective humidification module (4a, 4b) and fed to a respective fuel cell stack (14a, 14b), wherein at least one adjustable diaphragm is arranged along at least one secondary channel (2a, 2b) and / or outlet channel (5a, 5b), via which a cross-sectional area of ​​the respective secondary channel (2a, 2b) and / or outlet channel (5a, 5b) is to be regulated. [2] Humidification device according to claim 1, in which a respective fuel cell housing (18a, 18b) is connected via a gas supply channel (6a, 6b) to a respective sub-chamber (22a, 22b) within the humidification housing (11), wherein air from the respective fuel cell housing (18a, 18b) is to be supplied via the respective gas supply channel (6a, 6b) to the humidification module (4a, 4b) arranged in the respective sub-chamber (22a, 22b). [3] Humidification device according to one of the preceding claims, in which the humidification housing (11) has at least one outlet funnel (9) through which air is to be discharged from the humidification housing (11). [4] Humidification device according to claim 1 or 3, wherein at least one partition wall (8) is arranged in the humidification housing (11), with which the partial chambers (22a, 22b) are separated from one another. [5] Humidification device according to one of the preceding claims, in which each humidification module (4a, 4b) is designed as a moisture-transmitting membrane. [6] Fuel cell system for a motor vehicle, which comprises a number of fuel cell stacks (14a, 14b), wherein in each case one fuel cell stack (14a, 14b) is arranged in a fuel cell housing (18a, 18b), and a humidification device (10) according to one of the preceding claims, which has a humidification housing (11) and a main channel (1) which is divided at a transition point (30) into a number of secondary channels (2a, 2b) corresponding to the number of fuel cell stacks (14a, 14b), wherein at least one flap (3) is arranged at the transition point (30), wherein in each case one secondary channel (2a, 2b) merges into a humidification module (4a, 4b) arranged in the humidification housing (11), wherein in each case one humidification module (4a, 4b) merges into an outlet channel (5a, 5b) which in each case Fuel cell housing (18a, 18b) opens, in each of which a fuel cell stack (14a, 14b) is arranged,wherein, during operation of the humidification device (10), a flow of dry air is to be supplied via the main duct (1), regulated by adjusting a position of the at least one flap (3), and divided into a number of partial flows corresponding to the number of secondary ducts (2a, 2b), wherein a partial flow is to be supplied to a secondary duct (2a, 2b), wherein the respective partial flow is to be humidified via a respective humidification module (4a, 4b) and supplied to a respective fuel cell stack (14a, 14b), wherein at least one adjustable diaphragm is arranged along at least one secondary duct (2a, 2b) and / or outlet duct (5a, 5b), via which a cross-sectional area of ​​the respective secondary duct (2a, 2b) and / or outlet duct (5a, 5b) is to be regulated. [7] Method for operating a fuel cell system comprising a plurality of fuel cell stacks (14a, 14b), each fuel cell stack (14a, 14b) being arranged in a fuel cell housing (18a, 18b), and a humidification device (10), wherein the humidification device (10) has a humidification housing (11) and a main channel (1) which is divided at a transition point (30) into a number of secondary channels (2a, 2b) corresponding to the number of fuel cell stacks (14a, 14b), wherein at least one flap (3) is arranged at the transition point (30), wherein each secondary channel (2a, 2b) merges into a humidification module (4a, 4b) arranged in the humidification housing (11), wherein each humidification module (4a, 4b) merges into an outlet channel (5a, 5b) which opens into a fuel cell housing (18a, 18b) in each of which a fuel cell stack (14a, 14b) is arranged,wherein, during operation of the fuel cell system (12), a flow of dry air is supplied via the main duct (1), regulated by adjusting a position of the at least one flap (3), and divided into a number of partial flows corresponding to the number of secondary ducts (2a, 2b), wherein a partial flow is supplied to a secondary duct (2a, 2b), wherein the respective partial flow is humidified via a respective humidification module (4a, 4b) and supplied to a respective fuel cell stack (14a, 14b), wherein a cross-sectional area of ​​at least one secondary duct (2a, 2b) and / or outlet duct (5a, 5b) is regulated by at least one adjustable aperture arranged along the at least one secondary duct (2a, 2b) and / or outlet duct (5a, 5b). [8] Method according to claim 7, in which a respective fuel cell housing (18a, 18b) is connected via a gas supply channel (6a, 6b) to a respective sub-chamber (22a, 22b) within the humidification housing (11), wherein air from the respective fuel cell housing (18a, 18b) is supplied via the respective gas supply channel (6a, 6b) to the humidification module (4a, 4b) arranged in the respective sub-chamber (22a, 22b). [9] Method according to one of claims 7 or 8, in which air is discharged from the humidification housing (11) via at least one outlet funnel (9). [10] Method according to one of claims 7 to 9, wherein humidified air is supplied to the humidification module (4a, 4b) arranged in the respective sub-chamber (22a, 22b). [11] Method according to claim 10, wherein humidified air is guided around the humidification module (4a, 4b) arranged in the respective sub-chamber (22a, 22b). [12] Method according to claim 10 or 11, wherein humidified air is passed through the humidification module (4a, 4b) arranged in the respective sub-chamber (22a, 22b). [13] Method according to claim 10 or 12, wherein dry air is guided around the humidification module (4a, 4b) arranged in the respective sub-chamber (22a, 22b).

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