DE102022212595A1 - Silencer for an exhaust system of a fuel cell system - Google Patents

Abstract

The invention relates to a silencer (1) for an exhaust line of a fuel cell system (2) with a cavity (10), a sound-damping device (20) arranged within the cavity (10) for reducing noise from the exhaust gas flow (S), a water separation device (30) arranged within the cavity (10) upstream of the sound-damping device (20) for separating water from the exhaust gas flow (S), wherein the water separation device (30) has an impact element (32) arranged in the water separation chamber (31) for radially expanding the exhaust gas flow (S) flowing in through the inlet opening (11), and downstream of the impact element (32) a funnel-shaped guide element (33) for radially tapering the exhaust gas flow (S) expanded by the impact element (32).

Description

The present invention relates to a silencer for an exhaust system of a fuel cell system with the features of claim 1. Furthermore, the invention relates to a fuel cell system with the features of claim 15.

A fuel cell converts the chemical reaction energy of a continuously supplied fuel, e.g. hydrogen, and an oxidizing agent, e.g. oxygen, into electrical energy. Fuel cells are used, for example, in fuel cell vehicles to convert the electrical energy generated directly into movement using an electric drive or to temporarily store it in a drive battery. Fuel cells can also use other fuels in addition to hydrogen, in particular methanol, butane or natural gas.

To supply the fuel and the oxidizing agent, a fuel cell system uses several mechanical devices that generate noise during operation, which can be perceived as disturbing. To reduce the noise generated in the fuel cell system, silencers are installed in the fuel cell system, e.g. in an exhaust system.

The silencers used in this context can be based on the reflection principle or the absorption principle. A reflection silencer consists of chambers of different sizes that are connected to one another, for example by a perforated pipe that extends through the chambers. The sound waves are reflected in the chambers. By coupling the individual chambers, so-called resonators are created in which the sound waves are reflected, partially cancel each other out according to the interference principle and are thus dampened. Individual chambers can be adapted to a specific frequency range to be dampened by their size and/or the hole pattern of the perforation in the pipe. The larger the number of chambers present, the more efficient the damping is. An absorption silencer usually has only one chamber in which a perforated pipe runs. The chamber is filled with a sound-absorbing material, e.g. long-fiber mineral wool. The sound waves penetrate through the perforated pipe into the sound-absorbing material and are converted into heat by friction effects. The attenuation achieved depends on the material used, the stuffing density, the length and the layer thickness of the chamber.

The exhaust gas produced during the electricity generation reaction in a hydrogen-oxygen fuel cell, which is discharged in particular from the cathode of the fuel cell, contains water (mostly in the form of water vapor and water droplets) and has an exhaust gas temperature in the range of 80 °C. Because the exhaust gas temperature is below the boiling point of water, the water is difficult to evaporate and discharge. However, if exhaust gas that is too moist penetrates the silencer, the water vapor condenses, particularly on the surfaces of the silencer, which has a negative impact on the function of the silencer - regardless of whether it is based on the reflection principle or the absorption principle. In unfavorable cases, the moisture that has accumulated in the silencer causes additional noise, which is perceived as unpleasant.

To counteract this problem, the US 2013 175114 A1 a hybrid silencer is proposed in which a dehumidification chamber is connected upstream of a silencer device based on the reflection principle, which dehumidification chamber is essentially completely filled with a water-absorbing material. In order to ensure a suitable dehumidification function, however, the dehumidification chamber must have a much larger volume than the silencer device. Nevertheless, the exhaust gas in the dehumidification chamber can only be dehumidified to a certain extent, so that the condensate that continues to form in the silencer device must be absorbed by a part of the water-absorbing material that protrudes into the silencer device. In addition, the water absorbed by the water-absorbing material cannot be easily drained away, but usually has to be sucked out using a pump. Overall, this results in a relatively complex structure of the hybrid silencer, which takes up a relatively large amount of installation space and is complex to manufacture and operate.

The object of the present invention is therefore to provide a silencer for an exhaust system of a fuel cell system, with which a reliable reduction in the noise associated with the operation of the fuel cell system can be achieved while at least partially avoiding the disadvantages of the prior art. At least an alternative to existing solutions should be created. Furthermore, the object of the present invention is to provide a fuel cell system with such a silencer.

This object is achieved by a silencer having the features of claim 1 and a Fuel cell system with the features of claim 15. Preferred features are the subject of the dependent claims. Further advantages and features can be found in the general description and the embodiments.

The silencer according to the invention for an exhaust system of a fuel cell system has a cavity through which an exhaust gas flow of the fuel cell system can flow along a flow path from an inlet opening of the cavity to an outlet opening of the cavity. Furthermore, the silencer has a silencer device arranged within the cavity for reducing noise of the exhaust gas flow, wherein the silencer device has at least one silencer chamber. The silencer also has a water separator device for separating water from the exhaust gas flow. The water separator device has at least one water separator chamber and is also arranged within the cavity and upstream of the silencer device, such that the exhaust gas flow flowing in through the inlet opening must first pass through the water separator device, in particular the entire water separator device, before the exhaust gas flow flows into the silencer device. The water separation device has an impact element arranged in the water separation chamber for radially expanding an exhaust gas flow flowing in through the inlet opening and, downstream of the impact element, a funnel-shaped guide element for radially tapering the exhaust gas flow expanded by the impact element.

The exhaust gas flow, which is discharged, for example, from the cathode of a fuel cell of the fuel cell system and fed directly or indirectly to the silencer, can flow through the inlet opening of the cavity into the water separation chamber. 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 impact element and then narrowed again by the funnel-shaped guide element arranged downstream before the exhaust gas flow is fed to the silencer. In this way, the exhaust gas flow in the water separation chamber is guided along as large a surface as possible on which water contained in the exhaust gas can condense. The water can condense on the impact element, on the funnel-shaped guide element and on a wall delimiting the water separation chamber, in particular a wall of a housing of the silencer. This achieves a high degree of dehumidification, so that any impairment of the function of the downstream silencer device due to excessively humid exhaust gases is reduced or completely prevented.

The design of the water separation chamber means that water-absorbing material is not required, which simplifies the design of the silencer. Depending on the installation position of the silencer, the condensed water collects in a known area of the water separation chamber due to gravity and can be easily drained away actively or passively from there.

A "water separation device" is a device that primarily serves to separate water (and/or another liquid) from the exhaust gas. A silencer device is therefore not to be regarded as a water separation device, even if a certain amount of condensation and removal of moisture also occurs in the silencer chamber.

The impact element preferably has a cross-section that increases continuously from its upstream end to its downstream end. This results in a gradual radial expansion of the exhaust gas flow on the outer surfaces of the impact element. To promote a uniform and quiet flow, the impact element can be at least partially rotationally symmetrical. The impact element can have a conical, truncated cone or paraboloid flow body. The upstream end of the impact element can be designed as a rounded tip. The impact element is preferably hollow - e.g. in the form of a cap with its tip aligned with the inlet opening - which reduces the material costs and the weight of the silencer.

The funnel-shaped guide element defines a flow channel from its upstream end to its downstream end, with a flow cross-section that in particular is constantly decreasing. In this way, the exhaust gas flow expanded by the impact element is captured again, with the funnel shape reducing or even preventing the formation of turbulence - which often occurs in the area of sharp corners. This reduces pressure loss in the silencer. Furthermore, water condensed on the funnel-shaped guide element can slide along the surface of the guide element due to gravity and in this way be discharged, for example, to a drain opening in the water separation chamber. To promote a laminar and low-noise flow, the funnel-shaped guide element can be designed to be rotationally symmetrical. In particular The funnel-shaped guide element has a concave surface along which the exhaust gas flow can flow. This promotes a laminar and low-noise flow and increases the available condensation surface. In particular, the impact element and the funnel-shaped guide element are spaced apart from one another in the longitudinal direction of the silencer or in the main flow direction of the exhaust gas flow.

The silencer device preferably has a perforated pipe extending through the silencer chamber. In particular, an upstream pipe end is connected to the funnel-shaped guide element in such a way that the inside of the pipe is in fluid communication with the water separation chamber. A downstream pipe end is preferably connected to the outlet opening. The perforation of the pipe creates a fluid connection with the rest of the silencer chamber. The silencer device can basically be designed as a reflection silencer or as an absorption silencer. The silencer device preferably forms a reflection silencer. This makes it easy to carry out additional dehumidification in the silencer device by condensing the water contained in the exhaust gas on the surfaces of the walls of the silencer chamber. The size of the silencer chamber and/or the hole pattern of the perforation in the pipe can be adapted to a specific frequency range to be dampened.

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

In a further preferred embodiment of the silencer according to the invention, the impact element is designed to generate a swirl in the exhaust gas flow. For this purpose, the impact element preferably has one or more guide elements, e.g. in the form of guide vanes, which, due to their shape, cause the exhaust gas flow flowing along the impact element to swirl around an axis of rotation running parallel to the longitudinal direction of the silencer or to the main flow direction of the exhaust gas flow. The swirl movement curves the flow path of the exhaust gas flow and thus lengthens it, which further promotes dehumidification. Alternatively or additionally, the impact element can also have one or more depressions as guide elements.

Preferably, the funnel-shaped guide element is designed to feed the tapered exhaust gas flow to the silencer device. In this way, a particularly compact design of the silencer can be realized, in which further structures for feeding the exhaust gas flow can be dispensed with.

In a further preferred embodiment of the silencer according to the invention, the silencer has a condensation sieve that separates the water separation chamber into two sub-chambers. In this way, the exhaust gas flow is forced to pass through the condensation sieve arranged in the water separation chamber. The water contained in the exhaust gas flow can condense on the sieve lining, which further increases the degree of dehumidification of the water separation device. In particular, a mesh, wire mesh, wire grid and/or perforated sheet forms the sieve lining. The condensation sieve preferably has a mesh size of at least 160 µm, preferably at least 300 µm, particularly preferably at least 500 µm, and a maximum of 1000 µm, preferably a maximum of 900 µm. It has surprisingly been found that good dehumidification results can be achieved with such mesh sizes. The condensation screen is preferably arranged downstream of the impact element, so that the exhaust gas flow is already expanded and guided along the largest possible condensation surface before it hits the condensation screen. The condensation screen is particularly preferably arranged at least partially within the funnel-shaped guide element. In this way, the exhaust gas flow is directed from the funnel-shaped guide element onto the condensation screen and compressed before passing through the condensation screen, so that a pressure loss due to the flow resistance of the condensation screen is reduced. The condensation screen is preferably designed in the shape of a cylinder jacket. With this simple structural design, the condensation screen can be optimally positioned in the water separation chamber between the impact element and the funnel-shaped guide element. The condensation screen is preferably mounted on a support structure that spaced the impact element from the funnel-shaped guide 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 silencer or in the main flow direction of the exhaust gas flow. Preferably, the silencer has at least one heating element for heating the condensation screen. This ensures that the close-meshed condensation screen does not freeze at low outside temperatures. In order to provide a favorable heating output, the at least one heating element for heating the condensation screen is tion sieve is preferably arranged on or in the support structure on which the condensation sieve is mounted.

In a further preferred embodiment of the silencer according to the invention, the funnel-shaped guide element forms a partition wall between the water separation chamber and the sound-damping chamber. In this way, the two chambers are separated at least partially, preferably completely, by one and the same structure, whereby a particularly compact design of the silencer can be realized, in particular with a direct transition from the water separation chamber to the sound-damping chamber.

In a further preferred embodiment of the silencer according to the invention, the silencer device has at least one further silencer chamber downstream of the silencer chamber. Due to its structural design, the silencer according to the invention is ideally suited for an extension of the silencer device by one or more silencer chambers, which can be implemented in a simple manner. This promotes both the damping and the additional dehumidification. Each of the silencer chambers can be adapted to a different frequency range to be dampened by its size and/or the corresponding hole pattern of the perforation in the pipe. In particular, a perforated pipe extends through the silencer chambers, with the silencer chambers being separated from one another outside the pipe by partition walls. For optimal damping, the silencer device preferably has two, particularly preferably four silencer chambers.

In a further preferred embodiment of the silencer according to the invention, the cavity extends along a longitudinal central axis and in particular rotationally symmetrical about the longitudinal central axis, with the water separator and the silencer device being arranged centered on the longitudinal central axis. The exhaust gas flow therefore only has to change its flow direction slightly when passing from the water separator to the silencer device, which promotes a uniform and quiet flow of the exhaust gas flow. Furthermore, a compact design of the silencer can be achieved in this way. In particular, the inlet opening and the outlet opening are arranged centered on the longitudinal central axis. The cavity is preferably at least partially, preferably completely, cylindrical or made up of several coaxially aligned cylindrical partial cavities.

In a further preferred embodiment of the silencer according to the invention, the silencer has a housing that at least partially delimits the cavity, the housing delimiting at least the outer surface(s) of the cavity, the silencer having a structure that can be assembled from modules or formed in one piece and can be inserted into the housing as a whole, the structure together with the housing forming the water separating device and the sound-damping device. The housing can release at least one insertion opening through which the structure can be inserted into the housing. The insertion opening can be closed by means of a separate cover. Alternatively, part of the structure can form the cover and close the insertion opening when the structure is inserted into the housing. In particular, the structure has the impact element, the funnel-shaped guide element, the perforated tube and, if there are several sound-damping chambers, one or more partition walls for separating the sound-damping chambers. The structure may, for example, comprise a support structure which fastens the impact element to the funnel-shaped guide element at a distance from the funnel-shaped guide element.

Preferably, the housing and/or the structure consists predominantly of a material comprising a thermoplastic.

In a further preferred embodiment of the silencer according to the invention, the silencer has a water collection chamber which at least partially surrounds the water separation chamber and which is in fluid communication with the water separation chamber via a drain opening in such a way that water separated from the exhaust gas flow can flow out of the water separation chamber, in particular independently due to gravity, into the water collection chamber and be collected there. In this way, the separated water is drained from the water separation chamber, thereby preventing water from accumulating in the water separation device, which could otherwise have a negative effect on dehumidification. It is also prevented that accumulated water is transported by the exhaust gas flow towards the silencer and impairs its function. Reliable drainage of water from the water separation chamber is crucial for the function of the silencer, since, for example, when a 100 kW fuel cell is running at full load, around 0.5 L of water can be separated from the exhaust gas. The water collected in the water collection chamber can be easily drained out of the water collection chamber, e.g. via a discharge opening, either actively - e.g. by a pump - or passively - e.g. independently due to gravity. The water collection chamber only has to surround a small area of the water separation chamber - e.g. an area that is located at the bottom in relation to the direction of gravity. The water collection chamber can therefore have a much smaller internal volume than the water separation chamber. The cavity and the water collection chamber are preferably separated by a wall of the cavity, which results in a compact design of the silencer.

In a further preferred embodiment of the silencer according to the invention, the water collection chamber furthermore surrounds the silencer chamber at least partially and is in fluid communication with the silencer chamber via an opening in such a way that water condensed from the exhaust gas flow can flow out of the silencer chamber, in particular independently due to gravity, into the water collection chamber. In this way, the separated water is drained out of the silencer chamber, thereby preventing water from accumulating in the silencer device, which could otherwise have a negative effect on the noise reduction. In order not to impair the function, the opening for the condensed water is preferably arranged in a corner of the silencer chamber. Preferably, if there are several adjacent silencer chambers separated by a partition wall, a common opening is arranged in the area of one end of the partition wall, whereby condensed water from both silencer chambers can flow through the opening into the water collection chamber.

The water collection chamber preferably extends along at least half of the total length, preferably at least two thirds of the total length of the cavity. This improves the absorption capacity of the water collection chamber. Furthermore, a compact design of the silencer can be achieved.

In a further preferred embodiment of the silencer according to the invention, the silencer has a heating element for heating at least part of a wall delimiting the water collection chamber. In this way, the water can be drained away even at low outside temperatures, where freezing of the condensate is to be expected. The heating element can extend along at least half of the total length, preferably at least two thirds of the total length of the water collection chamber. The heating element is preferably embedded in an area of the wall delimiting the water collection chamber that surrounds the drain opening.

The silencer can be provided with a nozzle in the area of the inlet opening and in the area of the outlet opening, to which an exhaust pipe section of the exhaust system can be attached.

According to what has already been described above and what has been described below, the object posed at the outset is also achieved by a fuel cell system having the features of claim 15.

The fuel cell system according to the invention has a fuel cell, an exhaust line leading from the fuel cell and a silencer according to the invention installed in the exhaust line. The advantages of the silencer described above and below are realized accordingly for the fuel cell system in this way.

In laboratory tests, by comparing the relative humidity and the temperature at the inlet and outlet openings, it was found that the silencer according to the invention is able to separate approximately 75% to 80% of the moisture from the exhaust gas stream.

It is expressly pointed out that the embodiments of the invention explained above can be combined with the subject matter of the independent claims, either individually or in any technically reasonable combination, including with one another.

• 1 ein Ausführungsbeispiel eines erfindungsgemäßen Brennstoffzellensystems;
• 2 ein erstes Ausführungsbeispiel eines erfindungsgemäßen Schalldämpfers in einer Schnittdarstellung;
• 3 ein zweites Ausführungsbeispiels eines erfindungsgemäßen Schalldämpfers in einer Schnittdarstellung; und
• 4 eine Frontansicht eines Prallelements, wie es in einem der Ausführungsbeispiele gemäß 1 oder 2 eingesetzt werden kann.

Modifications and embodiments of the invention as well as further advantages and details of the invention can be found in the following description and the drawings. The schematic figures show:

• 1 an embodiment of a fuel cell system according to the invention;
• 2 a first embodiment of a silencer according to the invention in a sectional view;
• 3 a second embodiment of a silencer according to the invention in a sectional view; and
• 4 a front view of an impact element as it is in one of the embodiments according to 1 or 2 can be used.

Parts that have the same or similar effect are provided with identical reference numbers where appropriate.

Individual technical features of the embodiments described below can also be used in combination with the previously described embodiments. play a role and the features of the independent claims and any further claims are combined to form subject matter according to the invention.

1 shows an embodiment of a fuel cell system 2 according to the invention. Hydrogen 5 and oxygen-containing air 6 are fed to a fuel cell 3, in the present case a hydrogen-oxygen fuel cell. A compressor is often used to feed the air 6, the operation of which is accompanied by considerable noise. A silencer 1 according to the invention is arranged in the exhaust line 4 of the fuel cell system 2. An exhaust gas feed line 4a conveys an exhaust gas flow S from the fuel cell 1 to the silencer 1, while an exhaust gas discharge line 4a conveys the dehumidified and noise-reduced exhaust gas flow S away from the silencer 1 - e.g. towards a tailpipe of the exhaust line 4.

2 shows a first embodiment of a silencer 1 according to the invention for an exhaust line 4 of a fuel cell system 2 in a sectional view. The silencer 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 position of the inlet opening 11 and the outlet opening define a main flow direction R, which in the present case runs parallel to the longitudinal center axis A of the silencer 1. A silencer device 20 for reducing noise of the exhaust gas flow S is arranged within the cavity 10. Furthermore, a water separator device 30 for separating water from the exhaust gas flow S is arranged within the cavity 10 upstream of the silencer device 20, wherein the water separator device 30 has a water separator chamber 31. Inside the water separation chamber 31, an impact element 32 is arranged for radially expanding the exhaust gas flow S flowing in through the inlet opening 11. Downstream of the impact element 32, a funnel-shaped guide element 33 is arranged for radially tapering the exhaust gas flow S expanded by the impact element 32.

The exhaust gas stream S can be supplied from the fuel cell 3 via an exhaust gas supply line 4a ( 1 ) of the exhaust line 4, which can be attached to the inlet nozzle 16 of the silencer 1, into the cavity 10. In the water separation chamber 31, the exhaust gas flow S is expanded by the impact element 32 and can thus be guided along an inner surface of a wall 35 delimiting the water separation chamber 31 before the exhaust gas flow S is tapered again by the funnel-shaped guide element 33 arranged downstream. The exhaust gas flow S is thereby guided along as large an area as possible on which water contained in the exhaust gas can condense. The exhaust gas flow S is dehumidified to a high degree before the exhaust gas flow S is fed to the silencer device 20. The function of the silencer device 20 is thus not impaired by excessive amounts of moisture. Furthermore, noise development due to moisture accumulating in the silencer device 20 is avoided. The dehumidified and noise-free exhaust gas can be discharged via an exhaust gas discharge line 4b ( 1 ) of the exhaust system 3, which can be attached to the outlet nozzle 17 of the silencer 1, can be led away from the silencer 1.

Due to the shape of the impact element 32, i.e. due to the cross-section that increases steadily from its upstream end 321 to its downstream end 322, a gradual radial expansion of the exhaust gas flow S occurs on the outer surfaces of the impact element 32. In order to achieve a sufficient radial expansion of the exhaust gas flow S, the cross-section of the impact element 32 at its downstream end 322 is larger than the flow cross-section of the inlet opening 11. To promote a uniform and quiet flow, the impact element 32 is essentially rotationally symmetrical and has a conical flow body with a rounded tip. To reduce the weight, the impact element 32 is hollow.

The funnel-shaped guide element 33 defines a flow channel 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 expanded by the impact element 32 is captured again, with the funnel shape reducing or even preventing the formation of turbulence and the associated pressure loss. For example, condensed water can slide along the surface of the guide element 33 due to gravity, e.g. in the direction of the drain opening 41, and can thus be drained away more effectively. To promote a laminar and low-noise flow, the funnel-shaped guide element 33 is rotationally symmetrical about the longitudinal center 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 increases the available condensation surface. In order to achieve the most compact possible design of the silencer 1, the funnel-shaped guide element 33 forms a partition wall between the water separation chamber 31 and the sound damping chamber 21a. Impact element 32 and funnel-shaped guide element 33 are spaced apart from one another in the longitudinal direction of the silencer 1 or in the main flow direction R of the exhaust gas flow S. The funnel-shaped guide element 33 is designed to feed the tapered exhaust gas flow S to the silencer device 20, ie the downstream end 332 of the funnel-shaped guide element 33 is directly connected to the upstream end of the perforated pipe 22. In the present case, the funnel-shaped guide element 32 and the perforated pipe 22 are designed as one piece.

In the present case, the silencer device 20 forms a reflection silencer with four silencer chambers 21 a, 21 b, 21 c, 21 d, through which a perforated tube 22 extends and which are further separated from one another by three partition walls 23 a, 23 b, 23 c.

The cavity 10 extends along the longitudinal center axis A of the silencer 1 and is rotationally symmetrical about the longitudinal center axis A. In the present case, the cavity 10 is cylindrical. The water separator device 30 and the silencer device 20 are arranged centered on the longitudinal center axis A. This promotes a uniform and quiet flow of the exhaust gas flow, since in particular there is no change in the main flow direction R (flow reversal). The advantageous flow behavior is also promoted by the fact that the inlet opening 11 and the outlet opening 12 are arranged centered on the longitudinal center axis A.

The silencer 1 has a housing 13 that delimits the outer surface of the cylindrical cavity 10. In the present case, the housing 13 also delimits an inlet-side front side of the cavity 10, while an outlet-side front side is delimited by a separate cover 15. Due to the structural design of the silencer 1, in particular due to the rotational symmetry of the individual components of the silencer 1 about the longitudinal center axis A, particularly simple production is possible. The silencer 1 can have a structure 14 that can be assembled from modules or formed as a single piece and that can be inserted as a whole into the housing 13, the structure 14 together with the housing 13 forming the water separating device 30 and the sound damping device 20. In the present case, the housing 13 for this purpose provides an insertion opening for the structure 14 on the outlet side that can be closed with the cover 15. The cover 15 can also be attached to the structure 14 or formed as a single piece with it. The structure 14 can, for example, have the impact element 32, the funnel-shaped guide element 33, the perforated tube 22 and the partition walls 23a, 23b, 23c for separating the sound-damping chambers 21a, 21b, 21c, 21d. The structure 14 can, for example, have a support structure 50 which fastens the impact element 32 to the funnel-shaped guide element 33 at a distance from the funnel-shaped guide element 33. In the present case, the structure has a further support structure 51 which spaced the impact element 32 from the housing 13 in the area of the inlet-side front side of the cavity 10. In some applications, it can also be advantageous to divide the structure 14 into individual modules on at least one cross-sectional plane.

The silencer 1 has a water collection chamber 40 which partially surrounds the water separation chamber 31 and is in fluid communication with the water separation chamber via a drain opening 41 in such a way that water separated from the exhaust gas flow S can flow out of the water separation chamber 31 into the water collection chamber 40 by gravity and be collected there. Separating water can thus flow out of the water separation chamber 31 in an optimal manner. The shape of the impact element 32 and the shape of the funnel-shaped guide element 33 promote a directed flow of the separated water in the direction of the drain opening 41.

The water collected in the water collection chamber 40 can be easily discharged from the water collection chamber or from the silencer, e.g. via a discharge opening 42, actively - e.g. by a pump - or passively - e.g. automatically due to gravity. The water collection chamber 40 only has to surround a small area of the water separation chamber 31 - e.g. an area located at the bottom with respect to the direction of gravity G, which can be located approximately between a "5 o'clock position" and a "7 o'clock position" when viewed parallel to the longitudinal center axis A. The water collection chamber 40 can therefore have a significantly smaller internal volume than the water separation chamber 31. The cavity 10 and the water collection chamber 40 are separated by a wall of the cavity 10, whereby a compact structure of the silencer 1 is achieved. A wall delimiting the water collection chamber 40 can also be part of the housing 13 and in particular be formed integrally therewith. In this case, a partition wall that can be inserted into the housing 13 can be provided, which separates the water separation chamber 31 from the water collection chamber 40.

The water collecting chamber 40 further partially surrounds the silencer chambers 21a, 21b, 21c, 21d and is in fluid communication with the silencer chambers 21a, 21b, 21c, 21d via openings 41a, 41b, 41c such that from the exhaust gas flow S condensed water from the sound dampening chambers 21a, 21b, 21c, 21d can flow out into the water collection chamber 40 by gravity. In this way, water accumulation in the sound dampening device 20 is avoided, which could otherwise have a negative effect on the noise dampening. In order not to impair the function of the sound dampening device 20, the openings 41a, 41b, 41c for the condensed water are preferably arranged in the corners of the sound dampening chambers 21a, 21b, 21c, 21d, with adjacent sound dampening chambers 21a, 21b, 21c, 21d having a common opening 41a, 41b, 41c in the area of a front side of the respective partition wall 23a, 23b, 23c.

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

The silencer 1 has a heating element 43 for heating at least part of a wall delimiting the water collection chamber 40. In this way, the water can be drained away even at low outside temperatures, where freezing of the condensate is to be expected. The heating element 43 is embedded in the wall 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 an area of the wall delimiting the water collection chamber 40 that surrounds the discharge opening 42. Several heating elements 43 can also be provided.

3 shows a second embodiment of a silencer 1 according to the invention for an exhaust line 4 of a fuel cell system 2 in a sectional view. The silencer 1 of the second embodiment differs from the silencer 1 of the first embodiment only in that the silencer 1 has a condensation screen 34 that separates the water separation chamber 31 into two sub-chambers 311, 312. In order to get from the first sub-chamber 311 into the second sub-chamber, the exhaust gas flow must pass through the condensation screen 34, whereby the water contained in the exhaust gas flow S can condense on the screen lining. The screen lining can be made of a mesh, wire mesh, wire grid and/or perforated sheet. The condensation screen 34 is arranged downstream of the impact element 32, so that the exhaust gas flow S is already expanded and guided along the largest possible condensation surface before it hits the condensation screen 34. In addition, the condensation sieve 34 is arranged partially within the funnel-shaped guide element 33. In other words, the condensation sieve 34 and the funnel-shaped guide element 33 overlap in a longitudinal section. In this way, the exhaust gas flow S is directed from the funnel-shaped guide element 33 onto the condensation sieve 34 and compressed before passing through the condensation sieve 34, so that a pressure loss due to the flow resistance of the condensation sieve 34 is reduced. The condensation sieve 34 is designed in the shape of a cylinder jacket and is mounted on the support structure 50 which spaced the impact element 32 from the funnel-shaped guide element 33.

In the second embodiment, it is advantageous to divide the structure 14 into individual modules at least at a cross-sectional plane between the impact element 32 and the funnel-shaped guide element 33, so that the condensation sieve 34 can be easily attached to the structure 14. For example, a first module of the structure 14 can have the impact element 32 and the further support structure 51 and a second module of the structure 14 can have the support structure 50, the condensation sieve 43, the funnel-shaped guide element 33 and possibly the components belonging to the sound-damping device 20 (perforated pipe 22, partition walls 23a, 23b, 23c). The first module of the structure 14 can also have a cover that at least partially delimits the inlet-side end face of the cavity 10. The second module of the structure 14 can also have a cover that at least partially delimits the outlet-side end face of the cavity 10.

4 shows a baffle element 32 in a front view (viewing direction in the main flow direction R), as it can also be used in the first or in the second embodiment. The baffle element 32 is designed to generate a swirl in the exhaust gas flow S. For this purpose, the baffle element 32 has, in addition to its 2 and 3 The conical flow body shown also has a plurality of guide elements in the form of guide vanes 323, which, due to their shape, cause the exhaust gas flow S flowing along the impact element 32 to swirl around the longitudinal center axis of the silencer. The swirl movement causes the flow path of the exhaust gas flow S to be curved and thus lengthened, which further promotes dehumidification.

It should be noted that “comprising” does not exclude other elements or steps, and “a” or “an” does not exclude a plurality.

The scope of the present invention is given by the patent claims and is not limited by the features explained in the description or shown in the figures.

List of reference symbols (part of the description)

1

silencer

2

Fuel cell system

3

Fuel cell

4

Exhaust system

4a

Exhaust gas supply line of the exhaust system

4b

Exhaust gas discharge of the exhaust system

5

hydrogen

6

Air

10

Silencer cavity

11

Inlet opening of the cavity

12

Outlet opening of the cavity

13

Silencer housing

14

Structure of the silencer

15

Silencer cover

16

Inlet port of the silencer

17

Silencer outlet port

20

Silencer silencer device

21a-d

Silencing chambers of the silencer device

22

perforated pipe of the silencer

23a-c

Partition walls of the silencer

30

Water separator

31

Water separation chamber of the water separation device

311

first sub-chamber of the water separation chamber

312

second sub-chamber of the water separation chamber

32

Impact element of the water separator

321

upstream end of the impact element

322

downstream end of the impact element

323

Guide elements of the impact element

33

funnel-shaped guide element of the water separator

331

upstream end of the funnel-shaped guide element

332

downstream end of the funnel-shaped guide element

34

Condensation sieve of the water separator

35

Wall defining the water separation chamber

40

Silencer water collection chamber

41

Drain opening of the water collection chamber

41a-c

Openings of the water collection chamber

42

Drain opening of the water collection chamber

43

Heating element of the silencer

50

Support structure

51

further support structure

A

Longitudinal center axis of the silencer

G

Gravitational direction

L

Total length of cavity

R

Main flow direction of the exhaust gas flow

S

Exhaust gas flow

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely to provide the reader with better information. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 2013175114 A1 [0006]

Claims (15)

Silencer (1) for an exhaust line of a fuel cell system (2) with 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), a sound-damping device (20) arranged within the cavity (10) for reducing a noise of the exhaust gas flow (S), wherein the sound-damping device (20) has at least one sound-damping chamber (21a, 21b, 21c, 21d), a water-separating device (30) arranged within the cavity (10) upstream of the sound-damping device (20) for separating water from the exhaust gas flow (S), wherein the water-separating device (30) has at least one water-separating chamber (31), wherein the water-separating device (30) has an impact element (32) arranged in the water-separating chamber (31) for radially expanding the Inlet opening (11) of the incoming exhaust gas flow (S) and downstream of the impact element (32) a funnel-shaped guide element (33) for radially tapering the exhaust gas flow (S) expanded by the impact element (32). Silencer (1) after Claim 1 , wherein the impact element (32) has a cross-section which in particular increases continuously from its upstream end (321) to its downstream end (322). Silencer (1) after Claim 1 or 2 , wherein the cross-section of the impact element (32) at its downstream end (322) is larger than the flow cross-section of the inlet opening (11). Silencer (1) according to one of the preceding claims, wherein the impact element (32) is designed to generate a swirl in the exhaust gas flow (S). Silencer (1) according to one of the preceding claims with a condensation sieve (34) separating the water separation chamber (31) into two partial chambers (311, 312). Silencer (1) after Claim 5 , wherein the condensation sieve (34) is arranged between the impact element (32) and the funnel-shaped guide element (33). Silencer (1) after Claim 6 , wherein the condensation sieve (34) is cylindrical in shape. Silencer (1) according to one of the preceding claims, wherein the funnel-shaped guide element (33) forms a partition wall between the water separation chamber (31) and the sound damping chamber (21a). Silencer (1) according to one of the preceding claims, wherein the silencer device (20) has at least one further silencer chamber (21b, 21c, 21d) downstream of the silencer chamber (21a). Silencer (1) according to one of the preceding claims, wherein the cavity (10) extends along a longitudinal central axis (A) and in particular rotationally symmetrical about the longitudinal central axis (A), wherein the water separation device (30) and the sound damping device (20) are arranged centered to the longitudinal central axis (A). Silencer (1) after Claim 10 , wherein the cavity (10) is cylindrical or is formed from a plurality of coaxially aligned cylindrical partial cavities, wherein the silencer (1) has a housing (13) which at least partially delimits the cavity (10), wherein the housing (13) delimits at least the outer surface(s) of the cavity (10), wherein the silencer (1) has a structure (14) which can be assembled from modules or is formed in one piece and which can be inserted as a whole into the housing (13), wherein the structure (14) together with the housing (13) forms the water separation device (30) and the sound damping device (20). Silencer (1) with a water collection chamber (40) which at least partially surrounds the water separation chamber (31) and which is in fluid communication with the water separation chamber (31) via a drain opening (41) such that water separated from the exhaust gas flow (S) can flow out of the water separation chamber (31), in particular independently due to gravity, into the water collection chamber (40) and be collected there. Silencer (1) after Claim 12 , wherein the water collection chamber (40) furthermore at least partially surrounds the silencer chamber(s) (21a, 21b, 21c, 21d) and is in fluid-conducting connection with the silencer chamber(s) (21a, 21b, 21c, 21d) via an opening (41a, 41b, 41c) in such a way that water condensed from the exhaust gas flow (S) can flow out of the silencer chamber(s) (21a, 21b, 21c, 21d), in particular independently due to gravity, into the water collection chamber (40). Silencer (1) after Claim 12 or 13 with a heating element (43) for heating at least part of a wall delimiting the water collecting chamber (40). Fuel cell system (2) with a fuel cell (3), an exhaust line (4) leading from the fuel cell (3) and a silencer (1) installed in the exhaust line (4) according to one of the preceding claims.

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