Muffler for exhaust section of fuel cell system

Abstract

The invention relates to a muffler (1) for an exhaust section of a fuel cell system (2), comprising: a cavity (10); a silencing device (20) arranged in the cavity (10) for reducing the noise of the exhaust flow (S); a water separation device (30), which is arranged in the chamber (10) upstream of the sound attenuation device (20), for removing water from the exhaust gas flow (S), the water separation device (30) having: a baffle element (32), which is arranged in the water separation chamber (31), for radially widening the exhaust gas flow (S) flowing in through the inlet opening (11); and a funnel-shaped guide element (33) located downstream of the baffle element (32) for radially narrowing the exhaust gas flow (S) widened by the baffle element (32).

Description

Field of the Invention

[0001] The present invention relates to a muffler for an exhaust section of a fuel cell system having the features of claim 1. The present invention also relates to a fuel cell system having the features of claim 15. Background Art

[0002] A fuel cell converts the chemical reaction energy of continuously supplied fuel (such as hydrogen) and an oxidant (such as oxygen) into electrical energy. A fuel cell is used, for example, in a fuel cell vehicle to directly convert the generated electrical energy into motion by an electric drive system or to temporarily store it in a drive battery. In addition to hydrogen, a fuel cell can also use other fuels, especially methanol, butane, or natural gas.

[0003] In order to supply fuel and an oxidant, a plurality of mechanical devices are used in a fuel cell system, and these mechanical devices generate noise during operation, and this noise may be uncomfortable. In order to reduce the noise generated in the fuel cell system, a muffler is installed in the fuel cell system, for example, in the exhaust section.

[0004] The muffler used in this case can be based on the resonance principle or the absorption principle. A resonator-type muffler consists of chambers of different sizes, which are connected to each other, for example, by perforated pipes extending through these chambers. Sound waves are reflected in the chambers. By connecting the individual chambers together, so-called resonators are formed, and the sound waves are reflected in these resonators and partially cancel each other out according to the interference principle and are thus muffled. Here, each chamber can be adapted to a specific frequency range to be muffled in terms of its size and / or the hole pattern of the perforations in the pipe. The more chambers there are, the more effective the muffling usually becomes. An absorption-type muffler usually has only one chamber, and a perforated pipe extends in this chamber. The chamber is filled with a sound-absorbing material, such as long-fiber mineral wool. Sound waves enter the sound-absorbing material through the perforated pipe and are converted into heat by a frictional effect. The muffling obtained depends on the material used, the filling density, and the length and thickness of the chamber.

[0005] The exhaust gas generated during the power generation reaction in a hydrogen-oxygen fuel cell (especially discharged from the cathode of the fuel cell) contains water (usually in the form of steam and water droplets) and has an exhaust gas temperature in the range of 80 °C. Since the exhaust gas temperature is lower than the boiling temperature of water, the evaporation and discharge of water may be less effective. However, if the overly humid exhaust gas enters the muffler, the steam condenses especially on the surface of the muffler, which has a negative impact on the function of the muffler, regardless of whether the muffler is based on the resonance principle or the absorption principle. In an adverse case, the moisture accumulated in the muffler causes additional noise generation, which is unpleasant.

[0006] To solve this problem, US2013 175114A1 discloses a hybrid muffler in which, based on the resonance principle, a dehumidification chamber substantially completely filled with a water-absorbing material is arranged upstream of the sound-absorbing device. However, to ensure a proper dehumidification function, the volume of the dehumidification chamber must be much larger than the volume of the sound-absorbing device. However, the exhaust gas can only be dehumidified to a certain extent in the dehumidification chamber, such that the condensate that continues to form in the sound-absorbing device must be absorbed by a part of the water-absorbing material that extends into the sound-absorbing device. In addition, the water absorbed by the water-absorbing material cannot be easily discharged, but rather must generally be pumped away. Overall, this thus results in a relatively complex structure of the hybrid muffler, occupying a relatively large amount of structural space and having high production and operation costs. Summary of the Invention

[0007] Accordingly, it is an object of the present invention to provide a muffler for an exhaust section of a fuel cell system, by which noise associated with the operation of the fuel cell system can be reliably reduced while avoiding at least some of the disadvantages of the prior art. At least, an alternative to the existing solutions will be provided. It is also an object of the present invention to provide a fuel cell system having such a muffler.

[0008] This object is achieved by a muffler having the features of claim 1 and a fuel cell system having the features of claim 15. Preferred features are the subject matter of the dependent claims. Further advantages and features can be found in the general description and the exemplary embodiments.

[0009] The muffler for an exhaust section of a fuel cell system according to the present invention has a cavity through which an exhaust gas flow of the fuel cell system can flow from an inlet opening of the cavity to an outlet opening of the cavity along a flow path. The muffler further has a sound-absorbing device arranged in the cavity for reducing the noise of the exhaust gas flow, wherein the sound-absorbing device has at least one sound-absorbing chamber. The muffler additionally has a water separation device for removing water from the exhaust gas flow. The water separation device has at least one water separation chamber and is also arranged in the cavity and upstream of the sound-absorbing device in such a way that the exhaust gas flow flowing in through the inlet opening must first pass through the water separation device, in particular the entire water separation device, and then the exhaust gas flow flows into the sound-absorbing device. The water separation device has: a baffle element arranged in the water separation chamber for radially widening the exhaust gas flow flowing in through the inlet opening; and a funnel-shaped guiding element located downstream of the baffle element for radially narrowing the exhaust gas flow widened by the baffle element.

[0010] For example, the exhaust gas flow discharged from the cathode of the fuel cell of the fuel cell system and directly or indirectly supplied to the muffler can flow into the water separation chamber through the inlet opening of the cavity. In particular, the inlet opening of the cavity simultaneously forms the inlet opening of the water separation chamber. In the water separation chamber, the exhaust gas flow is first widened by the baffle element and then narrowed again by the funnel-shaped guiding element arranged downstream, and then the exhaust gas flow is supplied to the muffler. In this way, the exhaust gas flow is guided along as large a surface as possible in the water separation chamber, and the water contained in the exhaust gas can condense on this surface. Here, the water can condense on the baffle element, the funnel-shaped guiding element, and the wall defining the water separation chamber, in particular, the wall of the housing of the muffler. As a result, a high degree of dehumidification is obtained, so that the damage to the function of the downstream arranged sound absorption device by the overly humid exhaust gas is reduced or completely prevented.

[0011] By means of the structural configuration of the water separation chamber, the water absorption material can be omitted, which simplifies the structural design of the muffler. The condensed water accumulates in the previously known area of the water separation chamber under the action of gravity according to the installation position of the muffler, and can be discharged from it actively or passively in a simple manner.

[0012] The "water separation device" should be understood as a device mainly used to remove water (and / or different liquids) from the exhaust gas. Therefore, even if a certain amount of condensation and water discharge occur in the sound absorption chamber, the sound absorption device should not be considered as a water separation device.

[0013] The baffle element preferably has a cross-section that increases continuously, particularly from its upstream end to its downstream end. As a result, the exhaust gas flow gradually widens radially at the outer surface of the baffle element. To promote a uniform and low-noise flow, the baffle element can have at least a partially rotationally symmetric design. The baffle element can have a conical, frustoconical, or parabolic flow body here. The upstream end of the baffle element can be designed as a rounded end, in particular. The baffle element is preferably designed to be hollow, for example, in the form of a cap, with its end facing the inlet opening, which reduces the material cost and weight of the muffler.

[0014] The funnel-shaped guiding element defines a flow duct with a flow cross-section that particularly continuously decreases from its upstream end to its downstream end. In this way, the exhaust gas flow widened by the baffle element is intercepted again, wherein the funnel shape reduces or even avoids the formation of turbulence that is common in sharp corner regions. As a result, the pressure loss in the muffler can be reduced. In addition, the water that has condensed on the funnel-shaped guiding element can slide along the surface of the guiding element under the action of gravity and in this way, for example, be discharged into the outflow opening in the water separation chamber. In order to promote laminar and low-noise flow, the funnel-shaped guiding element can have a rotationally symmetric design. In particular, the funnel-shaped guiding element has a concave surface along which the exhaust gas flow can flow. This promotes laminar and low-noise flow and enlarges the available condensation surface. In particular, the baffle element and the funnel-shaped guiding element are spaced apart from each other in the longitudinal direction of the muffler or in the main flow direction of the exhaust gas flow.

[0015] The muffling device preferably has a perforated pipe extending through the muffling chamber. In particular, the upstream pipe end is connected to the funnel-shaped guiding element in such a way that the interior of the pipe is fluidly connected to the water separation chamber. The downstream pipe end is preferably connected to the outlet opening. Thus, the perforations of the pipe establish a fluid connection with the rest of the muffling chamber. The muffling device can in principle be designed as a resonator-type muffler or an absorption-type muffler. The muffling device preferably forms a resonator-type muffler. As a result, by condensing the water contained in the exhaust gas on the surface of the wall of the muffling chamber, supplementary dehumidification can occur in a simple manner in the muffling device. The dimensions of the muffling chamber and / or the hole pattern of the perforations in the pipe can thus be adapted to the specific frequency range to be muffled.

[0016] In a preferred embodiment of the muffler according to the invention, the cross-section of the baffle element at its downstream end is larger than the flow cross-section of the inlet opening. In this way, the exhaust gas flow is widened into a large volume and can be guided along a large condensation surface.

[0017] In another preferred embodiment of the muffler according to the invention, the baffle element is designed to generate vortices in the exhaust gas flow. For this purpose, the baffle element preferably has one or more guiding elements (e.g., in the form of guiding vanes) which, by virtue of their shape, cause the exhaust gas flow flowing along the baffle element to perform a vortex motion about a rotation axis extending parallel to the longitudinal direction of the muffler or parallel to the main flow direction of the exhaust gas flow. The flow path of the exhaust gas flow is bent and thus lengthened due to the vortex motion, with the result that dehumidification is further promoted. Alternatively or additionally, the baffle element can also have one or more recesses as guiding elements.

[0018] The funnel-shaped guiding element is preferably designed to supply the narrowed exhaust gas flow to the muffling device. In this way, a particularly compact structure of the muffler can be achieved, wherein additional structures for supplying the exhaust gas flow can be omitted.

[0019] In a further preferred embodiment of the muffler according to the invention, the muffler has a condensation screen that divides the water separation chamber into two sub-chambers. In this way, the exhaust gas flow is forced to pass through the condensation screen arranged in the water separation chamber. The water contained in the exhaust gas flow can condense on the screen lining, as a result of which the dehumidification degree of the water separation device is further increased. In particular, a net, wire mesh, wire gauze and / or perforated plate form the screen lining. The mesh size of the condensation screen is preferably at least 160 μm, preferably at least 300 μm, particularly preferably at least 500 μm, and not more than 1000 μm, preferably not more than 900 μm. It has surprisingly been shown that good dehumidification results can be obtained with such a mesh size. The condensation screen is preferably arranged downstream of the baffle element, such that the exhaust gas flow has been widened and guided along as large a condensation surface as possible before impinging on the condensation screen. The condensation screen is particularly preferably arranged at least partially within the funnel-shaped guiding element. In this way, the exhaust gas flow is guided from the funnel-shaped guiding element onto the condensation screen and compressed before it passes through the condensation screen, such that the pressure loss caused by the flow resistance of the condensation screen is reduced. The condensation screen mesh is preferably designed to have a cylindrical surface. With this simple structural configuration, the condensation screen can be optimally positioned in the water separation chamber between the baffle element and the funnel-shaped guiding element. The condensation screen is preferably mounted on a support structure that spaces the baffle element from the funnel-shaped guiding element. The support structure can have one or more support elements (e.g., in the form of support struts) extending in the longitudinal direction of the muffler or in the main flow direction of the exhaust gas flow. The muffler preferably has at least one heating element for heating the condensation screen. In this way, it is ensured that the narrow-mesh condensation screen does not freeze at low external temperatures. To provide a favorable heating capacity, the at least one heating element for heating the condensation screen is preferably arranged on or in the support structure on which the condensation screen is mounted.

[0020] In a further preferred embodiment of the muffler according to the invention, the funnel-shaped guiding element forms a partition wall between the water separation chamber and the sound-absorbing chamber. In this way, at least partial, preferably complete, separation of these two chambers is achieved by the same structure, as a result of which a particularly compact structure of the muffler can be implemented, in particular with a direct transition from the water separation chamber to the sound-absorbing chamber.

[0021] In a further preferred embodiment of the muffler according to the invention, the muffling device has at least one additional muffling chamber downstream of the muffling chamber. Due to its structural configuration, the muffler according to the invention is optimally suited for simply implementing an extension of the muffling device by means of one or more muffling chambers. As a result, muffling and supplementary dehumidification are promoted. Each muffling chamber can hereby be adapted to different frequency ranges to be muffled in terms of its dimensions and / or the corresponding hole pattern of the perforations in the tubes. In particular, the perforated tubes extend through these muffling chambers, wherein the muffling chambers are separated from one another by partition walls outside the tubes. For optimal muffling, the muffling device preferably has two muffling chambers, particularly preferably four muffling chambers.

[0022] In a further preferred embodiment of the muffler according to the invention, the cavity extends along a longitudinal central axis and in particular extends rotationally symmetrically about the longitudinal central axis, wherein the water separation device and the muffling device are arranged such that they are centered on the longitudinal central axis. Thus, when the exhaust gas flow enters the muffling device from the water separation device, the exhaust gas flow only needs to slightly change its flow direction, with the result that a uniform and low-noise flow of the exhaust gas flow is promoted. Furthermore, in this way, a compact structure of the muffler can be achieved. In particular, the inlet opening and the outlet opening are arranged such that they are centered on the longitudinal central axis. The cavity is preferably designed to be at least partially, preferably completely cylindrical, or formed by a plurality of cylindrical sub-cavities oriented coaxially with one another.

[0023] In a further preferred embodiment of the muffler according to the invention, the muffler has a housing that at least partially delimits the cavity, wherein the housing at least delimits the cylindrical surface of the cavity, wherein the muffler has a structural body that is formed such that it can be assembled from modules or formed integrally and can be inserted into the housing as a whole, wherein the structural body together with the housing forms the water separation device and the muffling device. The housing can hereby leave at least one insertion opening through which the structural body can be inserted into the housing. The insertion opening can be closed by means of a separate cover. Alternatively, a part of the structural body can form the cover and, when the structural body has been inserted into the housing, closes the insertion opening. In particular, the structural body has a baffle element, a funnel-shaped guiding element, a perforated tube, and, when there are a plurality of muffling chambers, one or more partition walls for separating the muffling chambers. The structural body can have, for example, a support structure spaced apart from the funnel-shaped guiding element that fastens the baffle element to the funnel-shaped guiding element.

[0024] The housing and / or the structural body preferably consist mainly of a material comprising a thermoplastic.

[0025] In another preferred embodiment of the muffler according to the invention, the muffler has a water collection chamber which at least partially surrounds the water separation chamber and is fluidly connected to the water separation chamber via an outflow opening in such a way that the water separated from the exhaust gas flow can automatically flow out of the water separation chamber, into the water collection chamber and be collected in the water collection chamber, in particular under the action of gravity. In this way, the separated water is discharged from the water separation chamber, with the result that accumulation of water in the water separation device is avoided, which otherwise could have a negative impact on dehumidification. Furthermore, it is prevented that the collected water is conveyed by the exhaust gas flow in the direction of the muffling device and that the function of the muffling device is adversely affected. Reliable discharge of water from the water separation chamber is crucial for the function of the muffler, since, for example, up to about 0.5 l of water can be separated from the exhaust gas when driving a 100 kW fuel cell at full power. The water collected in the water collection chamber can be discharged from the water collection chamber in a simple manner, for example actively (e.g. via a pump) or passively (e.g. automatically under the action of gravity) via a discharge opening. The water collection chamber only needs to surround a small area of the water separation chamber, for example the area located at the bottom with respect to the direction of gravity. Therefore, the internal volume of the water collection chamber can be much smaller than the internal volume of the water separation chamber. The cavity and the water collection chamber are preferably separated by the wall of the cavity, with the result that a compact construction of the muffler is achieved.

[0026] In another preferred embodiment of the muffler according to the invention, the water collection chamber furthermore at least partially surrounds the muffling chamber and is fluidly connected to the muffling chamber via an opening in such a way that the water condensed from the exhaust gas flow can automatically flow out of the muffling chamber, into the water collection chamber, in particular under the action of gravity. In this way, the separated water is discharged from the muffling chamber, with the result that accumulation of water in the muffling device is avoided, which otherwise could have a negative impact on noise muffling. In order not to adversely affect the function, the opening for the condensed water is preferably arranged in a corner of the muffling chamber. When there are a plurality of adjacent muffling chambers separated by partition walls, a common opening is preferably arranged in the region of the end side of the partition wall, through which the condensed water can flow out of the two muffling chambers into the water collection chamber.

[0027] The water collection chamber preferably extends along at least half, preferably at least two thirds of the total length of the cavity. As a result, the storage capacity of the water collection chamber is promoted. Furthermore, a compact construction of the muffler can be achieved.

[0028] In a further preferred embodiment of the muffler according to the invention, the muffler has a heating element for heating at least a part of the wall defining the water collection chamber. In this way, it is also possible to ensure the discharge of water at low external temperatures where condensate is expected to freeze. The heating element can extend along at least half of the total length of the water collection chamber, preferably at least two-thirds of the total length. The heating element is preferably embedded in the region of the wall defining the water collection chamber around the discharge opening.

[0029] The muffler can in each case be provided with ports in the region of the inlet opening and in the region of the outlet opening, to which the exhaust pipe line part of the exhaust section can be fastened.

[0030] According to what has been described above and what will be described further below, the object stated at the beginning is also achieved by a fuel cell system having the features of claim 15.

[0031] The fuel cell system according to the invention has a fuel cell, an exhaust section starting from the fuel cell, and a muffler according to the invention installed in the exhaust section. The advantages of the muffler described above and below are correspondingly implemented for the fuel cell system in this way.

[0032] In laboratory experiments, by comparing the relative humidity and temperature at the inlet opening and the outlet opening, it has been shown that the muffler according to the invention is capable of separating approximately 75% to 80% of the moisture from the exhaust stream.

[0033] It is to be expressly noted that the above-described embodiments of the invention (each used individually or in any technically meaningful combination with one another) can each be combined with the subject matter of the independent claims. Description of the Drawings

[0034] Modifications and embodiments of the invention, as well as further advantages and details of the invention, can be found in the following substantial description and the drawings. In the schematic diagrams:

[0035] Figure 1 shows an exemplary embodiment of a fuel cell system according to the invention;

[0036] Figure 2 shows a first exemplary embodiment of a muffler according to the invention in a sectional view;

[0037] Figure 3 shows a second exemplary embodiment of a muffler according to the invention in a sectional view; and

[0038] Figure 4 shows as can be in accordance with Figure 1 or Figure 2 a front view of a baffle element as used in one of the exemplary embodiments.

[0039] List of Reference Signs (Part of the Specification)

[0040] 1. Muffler

[0041] 2. Fuel Cell System

[0042] 3. Fuel Cell

[0043] 4. Exhaust Section

[0044] 4a. Exhaust Supply Pipeline of the Exhaust Section

[0045] 4b. Exhaust Discharge Pipeline of the Exhaust Section

[0046] 5. Hydrogen

[0047] 6. Air

[0048] 10. Cavity of the Muffler

[0049] 11. Inlet Opening of the Cavity

[0050] 12. Outlet Opening of the Cavity

[0051] 13. Housing of the Muffler

[0052] 14. Structure of the Muffler

[0053] 15. Cover of the Muffler

[0054] 16. Inlet Port of the Muffler

[0055] 17. Outlet Port of the Muffler

[0056] 20. Sound Absorbing Device of the Muffler

[0057] 21a - d. Sound Absorbing Chambers of the Sound Absorbing Device

[0058] 22. Perforated Pipe of the Sound Absorbing Device

[0059] 23a - c. Partition Walls of the Sound Absorbing Device

[0060] 30. Water Separation Device

[0061] 31. Water Separation Chamber of the Water Separation Device

[0062] 311. First Sub - chamber of the Water Separation Chamber

[0063] 312. Second Sub - chamber of the Water Separation Chamber

[0064] 32. Baffle Element of the Water Separation Device

[0065] 321. Upstream End of the Baffle Element

[0066] The downstream end of the baffle element

[0067] The guiding element of the baffle element

[0068] The funnel-shaped guiding element of the water separation device

[0069] The upstream end of the funnel-shaped guiding element

[0070] The downstream end of the funnel-shaped guiding element

[0071] The condensation sieve of the water separation device

[0072] The wall defining the water separation chamber

[0073] The water collection chamber of the muffler

[0074] The outflow opening of the water collection chamber

[0075] The openings of the water collection chamber a-c

[0076] The discharge opening of the water collection chamber

[0077] The heating element of the muffler

[0078] The support structure

[0079] Another support structure

[0080] The longitudinal central axis of the muffler

[0081] The direction of gravity

[0082] The total length of the cavity

[0083] The main flow direction of the exhaust gas flow

[0084] The exhaust gas flow Detailed implementation mode

[0085] Where appropriate, parts with the same or similar functions are provided with the same reference numerals.

[0086] The individual technical features of the exemplary embodiments described below can also be combined with the above exemplary embodiments and with the features of the independent claims and any additional claims to form the inventive subject matter.

[0087] Figure 1An exemplary embodiment of a fuel cell system 2 according to the present invention is shown. Hydrogen 5 and air 6 containing oxygen are supplied to a fuel cell 3, which in this example is a hydrogen-oxygen fuel cell. A compressor is typically used to supply the air 6, and its operation is accompanied by a considerable amount of noise generation. A muffler 1 according to the present invention is arranged in an exhaust section 4 of the fuel cell system 2. An exhaust supply line 4a conveys an exhaust gas flow S of the fuel cell 1 to the muffler 1, while an exhaust discharge line 4a conveys the dehumidified and noise-reduced exhaust gas flow S away from the muffler 1, for example, to an end pipe of the exhaust section 4.

[0088] Figure 2 A first exemplary embodiment of a muffler 1 for an exhaust section 4 of a fuel cell system 2 according to the present invention is shown in a sectional view. The muffler 1 has a cavity 10 through which an exhaust gas flow S of the fuel cell system can flow from an inlet opening 11 to an outlet opening 12. The positions of the inlet opening 11 and the outlet opening define a main flow direction R which, in this example, extends parallel to a longitudinal central axis A of the muffler 1. Inside the cavity 10, a noise reduction device 20 for reducing the noise of the exhaust gas flow S is arranged. Furthermore, a water separation device 30 for removing water from the exhaust gas flow S is arranged upstream of the noise reduction device 20 inside the cavity 10, and the water separation device 30 has a water separation chamber 31. Inside the water separation chamber 31, a baffle element 32 is arranged which is used to radially broaden the exhaust gas flow S flowing in through the inlet opening 11. Downstream of the baffle element 32, a funnel-shaped guiding element 33 is arranged which is used to radially narrow the exhaust gas flow S broadened by the baffle element 32.

[0089] The exhaust gas flow S can be guided from the fuel cell 3 into the cavity 10 via the exhaust supply line 4a ( Figure 1 ) of the exhaust section 4, and this exhaust supply line can be fastened to an inlet port 16 of the muffler 1. The exhaust gas flow S is broadened by the baffle element 32 in the water separation chamber 31 and can thus be guided along an inner surface of a wall 35 defining the water separation chamber 31, after which the exhaust gas flow S is narrowed again by the funnel-shaped guiding element 33 arranged downstream. The exhaust gas flow S is thus guided along as large a surface as possible on which water contained in the exhaust gas can condense. Before the exhaust gas flow S is supplied to the noise reduction device 20, the exhaust gas flow S is highly dehumidified. Thus, the function of the noise reduction device 20 is not adversely affected by an excessive amount of moisture. Furthermore, noise generated by moisture accumulating in the noise reduction device 20 is avoided. The dehumidified and noise-free exhaust gas can be guided away from the muffler 1 via the exhaust discharge line 4b ( Figure 1 ) of the exhaust section 3, and this exhaust discharge line can be fastened to an outlet port 17 of the muffler 1.

[0090] The gradual radial widening of the exhaust gas flow S at the outer surface of the baffle element 32 takes place by virtue of the shape of the baffle element 32, i.e. the cross-section increases continuously from its upstream end 321 to its downstream end 322. In order to obtain a sufficient radial widening of the exhaust gas flow S, the cross-section of the baffle element 32 at its downstream end 322 is larger than the flow cross-section of the inlet opening 11. In order to promote a uniform and low-noise flow, the baffle element 32 is designed to be substantially rotationally symmetric and has a conical flow body with rounded ends. The baffle element 32 is designed to be hollow in order to reduce the weight.

[0091] The funnel-shaped guide element 33 delimits a flow duct with a continuously decreasing flow cross-section from its upstream end 331 to its downstream end 332. In this way, the exhaust gas flow S widened by the baffle element 32 is intercepted again, wherein the generation of turbulence and the associated pressure losses are reduced or even avoided by the funnel shape. Condensate can slide along the surface of the guide element 33 under the action of gravity, for example in the direction of the outflow opening 41, and is thus better discharged. In order to promote a laminar and low-noise flow, the funnel-shaped guide element 33 is designed to be rotationally symmetric about the longitudinal central axis A. The funnel-shaped guide element 33 has a concave surface along which the exhaust gas flow S can flow. This promotes a laminar and low-noise flow and enlarges the available condensate surface. In order to achieve the most compact possible structure of the muffler 1, the funnel-shaped guide element 33 forms a partition wall between the water separation chamber 31 and the muffling chamber 21a. The baffle element 32 and the funnel-shaped guide element 33 are spaced apart from each other in the longitudinal direction of the muffler 1 or in the main flow direction R of the exhaust gas flow S. The funnel-shaped guide element 33 is designed to supply the narrowed exhaust gas flow S to the muffling device 20, i.e. the downstream end 332 of the funnel-shaped guide element 33 is adjacent to the upstream end of the perforated pipe 22. In the present example, the funnel-shaped guide element 32 and the perforated pipe 22 are integrally formed.

[0092] In the present example, the muffling device 20 forms a resonator-type muffler having four muffling chambers 21a, 21b, 21c, 21d, through which the perforated pipe 22 extends, and these muffling chambers are additionally separated from each other by three partition walls 23a, 23b, 23c.

[0093] The cavity 10 extends along the longitudinal central axis A of the muffler 1 and is rotationally symmetric about the longitudinal central axis A. In the present example, the cavity 10 is designed to be cylindrical. The water separation device 30 and the muffling device 20 are arranged such that they are centered on the longitudinal central axis A. As a result, a uniform and low-noise flow of the exhaust gas is promoted, especially since a change (flow reversal) in the main flow direction R is omitted. The inlet opening 11 and the outlet opening 12 are arranged such that they are centered on the longitudinal central axis A, which also promotes a favorable flow behavior.

[0094] The muffler 1 has a housing 13 that defines the cylindrical surface of the cylindrical cavity 10. In this example, the housing 13 additionally defines the inlet end side of the cavity 10, while the outlet end side is defined by a separate cover 15. Due to the structural configuration of the muffler 1, especially due to the rotational symmetry of the individual parts of the muffler 1 about the longitudinal central axis A, the production is particularly simple. The muffler 1 can have a structural body 14 that is formed such that it can be assembled from modules or formed integrally and can be inserted as a whole into the housing 13, where the structural body 14 together with the housing 13 forms a water separation device 30 and a silencing device 20. In this example, for this purpose, the housing 13 has an insertion opening on the outlet side for the structural body 14, which insertion opening can be closed by the cover 15. The cover 15 can also be fastened to the structural body 14 or formed integrally therewith. The structural body 14 can have, for example, baffle elements 32, funnel-shaped guiding elements 33, perforated pipes 22, and partition walls 23a, 23b, 23c for separating the silencing chambers 21a, 21b, 21c, 21d. The structural body 14 can have, for example, a support structure 50 spaced apart from the funnel-shaped guiding element 33, which support structure fastens the baffle element 32 to the funnel-shaped guiding element 33. In this example, the structural body has another support structure 51 that spaces the baffle element 32 from the housing 13 in the region of the inlet end side of the cavity 10. In some use cases, it may also be advantageous to divide the structural body 14 into separate modules at at least one cross-sectional plane.

[0095] The muffler 1 has a water collection chamber 40 that partially surrounds the water separation chamber 31 and is fluidly connected to the water separation chamber via an outflow opening 41 in such a way that the water separated from the exhaust gas stream S can automatically flow out of the water separation chamber 31 under the action of gravity, into the water collection chamber 40 and be collected therein. Thus, the separated water can optimally flow out of the water separation chamber 31. The shape of the baffle element 32 and the shape of the funnel-shaped guiding element 33 promote the directed flow of the separated water in the direction of the outflow opening 41.

[0096] The water collected in the water collection chamber 40 can be discharged from the water collection chamber or the muffler in a simple manner, for example, actively (e.g., via a pump) or passively (e.g., automatically under the action of gravity) via the discharge opening 42. The water collection chamber 40 only needs to surround a small area of the water separation chamber 31, for example, the area located at the bottom relative to the direction of gravity G, which can be located between approximately the "5 o'clock position" and the "7 o'clock position" when observed parallel to the longitudinal central axis A. Therefore, the internal volume of the water collection chamber 40 can be much smaller than the internal volume of the water separation chamber 31. The cavity 10 and the water collection chamber 40 are separated by the wall of the cavity 10, and as a result, a compact structure of the muffler 1 is achieved. The wall defining the water collection chamber 40 can also be part of the housing 13 and can be formed integrally therewith in particular. In this case, a partition wall that can be pushed into the housing 13 can be provided, which separates the water separation chamber 31 from the water collection chamber 40.

[0097] The water collection chamber 40 also partially surrounds the muffler chambers 21a, 21b, 21c, 21d and is fluidly connected to the muffler chambers 21a, 21b, 21c, 21d via the openings 41a, 41b, 41c in such a way that the water condensed from the exhaust gas flow S can automatically flow out of the muffler chambers 21a, 21b, 21c, 21d under the action of gravity and into the water collection chamber 40. In this way, the accumulation of water in the muffler device 20 is avoided, which otherwise might have a negative impact on noise attenuation. In order not to adversely affect the function of the muffler device 20, the openings 41a, 41b, 41c for condensing water are preferably arranged in the corners of the muffler chambers 21a, 21b, 21c, 21d, where adjacent muffler chambers 21a, 21b, 21c, 21d have a common opening 41a, 41b, 41c in the end-side region of the corresponding partition walls 23a, 23b, 23c.

[0098] To provide sufficient storage capacity, the water collection chamber 40 extends substantially along the total length L of the cavity 10.

[0099] The muffler 1 has a heating element 43 that is used to heat at least a part of the wall defining the water collection chamber 40. In this way, it is also possible to ensure the discharge of water at low external temperatures where condensate freezing is expected. The heating element 43 is embedded in the wall here and extends along at least half of the total length L of the water collection chamber 40. The heating element 43 can alternatively be embedded in the region of the wall defining the water collection chamber 40 around the discharge opening 42. A plurality of heating elements 43 can also be provided.

[0100] Figure 3A second exemplary embodiment of a muffler 1 for an exhaust section 4 of a fuel cell system 2 according to the present invention is shown in a sectional view. The muffler 1 of the second exemplary embodiment differs from the muffler 1 of the first exemplary embodiment only in that the muffler 1 has a condensation screen 34 which divides the water separation chamber 31 into two sub-chambers 311, 312. In order to move from the first sub-chamber 311 into the second sub-chamber, the exhaust gas flow must pass through the condensation screen 34, where water contained in the exhaust gas flow S can condense on the screen lining. The screen lining can be formed by a mesh, wire mesh, wire gauze and / or perforated plate.

[0101] The condensation screen 34 is arranged downstream of the baffle element 32 such that the exhaust gas flow S has been widened and guided along as large a condensation surface as possible before impinging on the condensation screen 34. The condensation screen 34 is additionally partly arranged within the funnel-shaped guiding element 33. In other words, the condensation screen 34 and the funnel-shaped guiding element 33 overlap in a longitudinal section. In this way, the exhaust gas flow S is guided from the funnel-shaped guiding element 33 onto the condensation screen 34 and compressed before it passes through the condensation screen 34, such that the pressure loss caused by the flow resistance of the condensation screen 34 is reduced. The condensation screen 34 is designed to have a cylindrical surface and is mounted on a support structure 50 which spaces the baffle element 32 from the funnel-shaped guiding element 33.

[0102] In the second embodiment, it is advantageous to divide the structural body 14 into separate modules at least in the sectional plane between the baffle element 32 and the funnel-shaped guiding element 33 such that the condensation screen 34 can be simply fastened to the structural body 14. For example, a first module of the structural body 14 can have the baffle element 32 and another support structure 51, and a second module of the structural body 14 can have the support structure 50, the condensation screen 43, the funnel-shaped guiding element 33, and possibly components belonging to the silencing device 20 (perforated pipe 22, partition walls 23a, 23b, 23c). The first module of the structural body 14 can also have a cover which at least partly delimits the inlet end side of the cavity 10. The second module of the structural body 14 can also have a cover which at least partly delimits the outlet end side of the cavity 10.

[0103] Figure 4 A front view (viewed in the direction of the main flow direction R) shows the baffle element 32 which can also be used in the first exemplary embodiment and the second exemplary embodiment. The baffle element 32 is designed here to generate vortices in the exhaust gas flow S. For this purpose, the baffle element 32 in addition to its Figure 2 and Figure 3In addition to the conical flow body shown in the figure, it also has a plurality of guide elements in the form of guide vanes 323, and due to their shape, these guide elements cause the exhaust gas flow S flowing along the baffle element 32 to generate a vortex motion around the longitudinal central axis of the muffler. The flow path of the exhaust gas flow S is bent due to the vortex motion and is thus extended, as a result of which dehumidification is further promoted.

[0104] In addition, it should be mentioned that "comprising" and "having" do not exclude any other elements or steps, and "a" or "an" or "one" does not exclude a plurality.

[0105] The protection scope of the present invention is defined by the patent claims and is not limited by the features explained in the specification or shown in the drawings.

Claims

1. A muffler (1) for an exhaust section of a fuel cell system (2), the muffler having: A cavity (10) through which an exhaust gas flow (S) of the fuel cell system can flow from an inlet opening (11) through the cavity to an outlet opening (12), A silencing device (20), which is arranged in the cavity (10) and is used for reducing the noise of the exhaust gas flow (S), wherein, The muffling device (20) has at least one muffling chamber (21a, 21b, 21c, 21d), and a water separation device (30) which is arranged upstream of the muffling device (20) within the cavity (10) for removing water from the exhaust gas flow (S), wherein the water separation device (30) has at least one water separation chamber (31), Wherein the water separation device (30) has: a baffle element (32) which is arranged in the water separation chamber (31) for radially widening the exhaust gas flow (S) flowing in through the inlet opening (11); and a funnel-shaped guiding element (33) which is located downstream of the baffle element (32) for radially narrowing the exhaust gas flow (S) widened by the baffle element (32).

2. The muffler (1) according to claim 1, wherein, The baffle element (32) has a cross-section which increases in particular from its upstream end (321) to its downstream end (322).

3. The muffler (1) according to claim 1 or 2, wherein, The cross-section of the baffle element (32) at its downstream end (322) is larger than the flow cross-section of the inlet opening (11).

4. The muffler (1) according to one of the preceding claims, wherein, The baffle element (32) is designed to generate vortices in the exhaust gas flow (S).

5. The muffler (1) according to one of the preceding claims, the muffler having a condensation screen (34) which divides the water separation chamber (31) into two sub-chambers (311, 312).

6. The muffler (1) according to claim 5, wherein, The condensation screen (34) is arranged between the baffle element (32) and the funnel-shaped guiding element (33).

7. The muffler (1) according to claim 6, wherein, The condensation screen (34) is designed to have a cylindrical surface.

8. The muffler (1) according to one of the preceding claims, wherein, The funnel-shaped guiding element (33) forms a partition wall between the water separation chamber (31) and the muffling chamber (21a).

9. The muffler (1) according to one of the preceding claims, wherein, The muffling device (20) has at least one further muffling chamber (21b, 21c, 21d) downstream of the muffling chamber (21a).

10. The muffler (1) according to one of the preceding claims, wherein, The cavity (10) extends along a longitudinal central axis (A) and in particular extends rotationally symmetrically about the longitudinal central axis (A), wherein the water separation device (30) and the muffling device (20) are arranged such that they are centered on the longitudinal central axis (A).

11. The muffler (1) according to claim 10, wherein, The cavity (10) is designed to be cylindrical or is formed by a plurality of cylindrical sub-cavities which are coaxially oriented with respect to one another, wherein the muffler (1) has a housing (13) which at least partially bounds the cavity (10), wherein the housing (13) bounds at least one or more cylindrical surfaces of the cavity (10), wherein the muffler (1) has a structural body (14) which is formed such that the structural body can be assembled from modules or integrally formed and can be inserted as a whole into the housing (13), wherein the structural body (14) together with the housing (13) forms the water separation device (30) and the muffling device (20).

12. A muffler (1) having a water collection chamber (40) that at least partially surrounds the water separation chamber (31) and is fluidly connected to the water separation chamber (31) via an outflow opening (41) such that water separated from the exhaust gas flow (S) can automatically flow out of the water separation chamber (31), into the water collection chamber (40), and be collected in the water collection chamber, particularly under the action of gravity.

13. The muffler (1) according to claim 12, wherein, The water collection chamber (40) furthermore at least partially surrounds the one or more muffling chambers (21a, 21b, 21c, 21d) and is fluidly connected to the one or more muffling chambers (21a, 21b, 21c, 21d) via openings (41a, 41b, 41c) such that water condensed from the exhaust gas flow (S) can automatically flow out of the one or more muffling chambers (21a, 21b, 21c, 21d), into the water collection chamber (40), particularly under the action of gravity.

14. The muffler (1) according to claim 12 or 13, having a heating element (43) for heating at least a part of the wall defining the water collection chamber (40).

15. A fuel cell system (2) having: a fuel cell (3), an exhaust section (4) starting from the fuel cell (3), and a muffler (1) according to one of the preceding claims, the muffler being installed in the exhaust section (4).

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