DE102022212596A1 - Heated 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 silencer device (20) for reducing noise from the exhaust gas flow (S), a water separator device (30) arranged upstream of the silencer device (20) for separating water from the exhaust gas flow (S), a water collecting chamber (40) which at least partially surrounds the water separator chamber (31) and is in fluid communication with the water separator chamber (31) via a drain opening (41) in such a way that water separated from the exhaust gas flow (S) can flow out of the water separator chamber (31) into the water collecting chamber (40) and be collected there, and a heating device for heating at least part of a wall (43) delimiting the water collecting chamber (40).

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 11.

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.

In addition, when implementing a separate dehumidification of the exhaust gas in the silencer, there is the problem that the separated water can freeze, e.g. in winter at ambient temperatures close to freezing point, which can impair the function of the silencer or the drainage of the separated water from the silencer or, in the worst case, damage the silencer.

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 of the emissions associated with the operation can be achieved even at low ambient temperatures. 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 is to be created. Furthermore, it is the object of the present invention to provide a fuel cell system with such a silencer.

This object is achieved by a silencer with the features of claim 1 and a fuel cell system with the features of claim 11. Preferred features are the subject of the dependent claims. Further advantages and features can be found in the general description and the exemplary embodiments.

The silencer according to the invention for an exhaust system of a fuel cell system has an inlet opening and an outlet opening, wherein an exhaust gas flow of the fuel cell system can flow along a flow path from the inlet opening to the outlet opening. The silencer also has a silencer device for reducing noise of the exhaust gas flow, wherein the silencer device has at least one silencer chamber. Furthermore, the silencer has a water separation device arranged upstream of the silencer device for separating water from the exhaust gas flow, wherein the water separation device has at least one water separation chamber. 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. Furthermore, the silencer has a heating device for heating at least a part of a wall delimiting the water collecting chamber, wherein the heating device has at least one heating 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 dehumidified, for example by first widening the exhaust gas flow using an impact element and then narrowing it again using a funnel-shaped guide element arranged downstream, so that the exhaust gas flow is guided along the largest possible surface on which water contained in the exhaust gas can condense.

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 then easily flow out of the water collection chamber via the drain opening. In this way, the separated water is efficiently drained out of the water separation chamber, preventing water from accumulating in the water separation device, which could otherwise have a negative effect on dehumidification. It also prevents accumulated water from being transported by the exhaust gas flow towards the silencer and impairing 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 or the silencer, e.g. actively via a drainage opening - e.g. by a pump - or passively - e.g. automatically due to gravity.

Since the water collection chamber is usually located away from the flow path for the warm exhaust gas flow, there is a risk that the collected water will freeze at ambient temperatures close to freezing, which may impair or prevent the discharge of the separated water from the silencer. This risk is avoided by the heating device for heating at least part of a wall delimiting the water collection chamber.

According to a preferred embodiment of the silencer according to the invention, the at least one heating element of the heating device is embedded in the wall delimiting the water collecting chamber.

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 water collection chamber only needs to cover a small area of the water separation chamber surrounded - e.g. an area located at the bottom with respect to the direction of gravity. The water collection chamber can therefore have a much smaller internal volume than the water separation chamber.

In a preferred embodiment of the silencer according to the invention, the water collection chamber furthermore at least partially surrounds the silencer chamber and is in fluid communication with the silencer chamber via an opening such 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.

In a further preferred embodiment of the silencer according to the invention, the at least one heating element has two metallic electrodes and a heating element arranged at least partially between the electrodes and contacting both electrodes, wherein the heating element comprises a polymer-based material with a positive temperature coefficient. The heating element preferably consists of the polymer-based material with a positive temperature coefficient.

A material with a positive temperature coefficient (PTC) is a material in which the electrical resistance increases when its temperature rises. In the context of this invention, this refers in particular to a material that is designed in such a way that the material reaches a maximum temperature at a certain input voltage, since any further increase in temperature at a certain point in time would be accompanied by a significantly higher electrical resistance. In other words, the use of a PTC material creates a self-regulating heating element. If a voltage is applied to the two electrodes, a current flows from one electrode through the heater to the other electrode, heating the heater to a material-specific maximum temperature. The heater thus serves as a self-regulating heating resistor. In this way, the heating element can be directly contacted with a voltage source, e.g. a 12V or 24V vehicle battery, whereby a separate control and/or regulating device for regulating the heating output and any temperature sensors required for detecting the actual temperature can be dispensed with.

Various PTC materials based on (semi-)metals, ceramics or polymers are known. An example of a known polymer-based PTC material is "PTC rubber". According to the invention, the PTC material is polymer-based, i.e. the material has at least one polymer, whereby the material preferably has at least 50 vol.% of at least one polymer. This allows the heating element to be used as a structural component of the silencer and thus, in addition to its heating function, also to take on a supporting and/or space-enclosing function. The polymer-based material can also be processed easily and integrated without any problem into the other components of the silencer, which are preferably also made of a polymer material.

In addition, this makes it possible to dispense with separate insulation of the heater to protect it from corrosion caused by contact with the moist exhaust gas or the water condensed from the exhaust gas. The heater can thus be exposed to the atmospheres prevailing in the chambers of the silencer without any problems. In a preferred embodiment, at least one polymer of the material is a thermoplastic (TP) or a thermoplastic elastomer (TPE), in particular where the TP or TPE is mixed with conductive particles (e.g. soot or metal particles). The material is preferably designed to increase its electrical resistance at a predetermined maximum operating temperature by at least a factor of 5 compared to its electrical resistance at 20 °C, in particular where the maximum operating temperature is between 50 °C and 60 °C.

In a further preferred embodiment of the silencer according to the invention, the electrodes of the heating element are embedded in the heating body. In other words, the electrodes are completely surrounded by the polymer-based heating body material, i.e. on all sides, except for their electrical connection contacts. In this way, the electrodes are encapsulated to protect them in particular from the damp, warm environments of the silencer. Furthermore, the heating power of the heating element is increased because the possible current paths are no longer located exclusively in the area between the electrodes, but also in an adjacent area. Although the current initially flows directly from an elect rode through the part of the radiator located between the electrodes to the other electrode. However, when the area of the radiator located between the electrodes has heated up to such an extent that its resistance increases by a certain amount, the current also begins to flow through the adjacent areas of the radiator and thus heats them up.

In a further preferred embodiment of the silencer according to the invention, the heating element forms part of the wall delimiting the water collection chamber. In other words, the water collection chamber is delimited by a surface of the heating element, so that the heat generated by the heating element can interact directly with the internal volume of the chamber. In this way, a particularly efficient heat input into the water collection chamber is ensured. In addition, a compact structure of the silencer is created, since the heating element, in addition to its heating function, also has a supporting and/or space-enclosing function. The partition wall preferably comprises at least 50 vol.% of the polymer-based material with a positive temperature coefficient. The partition wall is particularly preferably made of the polymer-based material with a positive temperature coefficient.

In a further preferred embodiment of the silencer according to the invention, the wall delimiting the water collection chamber forms a partition between the water separation chamber and the water collection chamber, wherein the heating device has a heating element for heating the partition, which forms part of the partition, preferably the majority of the partition. In this way, at least a certain amount of heat can be introduced into the water separation chamber in order to minimize the risk of condensed water freezing there as well. In addition, in this way, a certain amount of heat can be introduced in the area of the at least one drain opening in the partition, which could otherwise become blocked at ambient temperatures close to freezing point due to its relatively small flow cross-section. The heating element for heating the partition particularly preferably has a first surface delimiting the water collection chamber and a second surface delimiting the water separation chamber.

In a further preferred embodiment of the silencer according to the invention, the silencer has a housing which delimits a cavity within the silencer and forms a receptacle for the partition wall designed as a separate component, wherein the partition wall received in the receptacle (e.g. pushed in) separates the cavity at least into the water separation chamber and the water intake chamber. This structural design allows the partition wall formed partially or completely by the radiator of the heating element to be easily integrated into the housing of the silencer. The housing and partition wall can be manufactured separately from different materials and then assembled. For example, the housing can be made from a polymer material (e.g. polypropylene or another thermoplastic) and the partition wall (at least partially) from the polymer-based material with positive temperature coefficients.

In a further preferred embodiment of the silencer according to the invention, the water collection chamber has a discharge opening through which collected water can be discharged from the silencer, in particular automatically due to gravity, wherein the heating device has a heating element for heating the discharge opening, which at least partially, preferably completely, surrounds the discharge opening. In this way, sufficient heat input is ensured in the area of the at least one discharge opening, which could otherwise become blocked due to its relatively small flow cross-section at ambient temperatures close to freezing point. The water collected in the water collection chamber can thus be reliably discharged from the water collection chamber or from the silencer via the discharge opening actively - e.g. by a pump - or passively - e.g. automatically due to gravity.

Preferably, the heating element for heating the discharge opening forms part of the wall surrounding the discharge opening. In other words, the water collection chamber in the area of the discharge opening is delimited by a surface of the heating body of the heating element for heating the discharge opening, so that the heat generated by the heating element can interact directly with the discharge opening and the internal volume of the chamber. In this way, a particularly efficient heat input is ensured, which minimizes the risk of the discharge opening freezing over. Preferably, at least one of the electrodes has a disc ring segment-shaped part that extends around the discharge opening. Preferably, at least one of the electrodes has a finger that extends into the nozzle. In particular, the fingers extend from the disc ring segment-shaped part(s). In this way, a particularly efficient heating of the area around the discharge opening is possible.

Preferably, the water collection chamber extends along at least half of the total length, preferably at least two thirds of the total length of an internal volume of the silencer, which is formed by the water collection chamber and the silencer chamber(s). This improves the absorption capacity of the water collection chamber. Furthermore, a compact design of the silencer can be achieved.

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.

Preferably, the housing consists of at least 50 vol.% of a material containing a thermoplastic.

According to what has already been described above and what has been described below, the object set out at the outset is also achieved by a fuel cell system having the features of claim 11.

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.

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 das Heizelement zum Beheizen der Trennwand aus 2 in einer Draufsicht;
• 4 das Heizelement zum Beheizen zum Beheizen der Abführöffnung aus 2 in einer detaillierten dreidimensionalen Darstellung. Gleich oder ähnlich wirkende Teile sind - sofern dienlich - mit identischen Bezugsziffern versehen.

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 the heating element for heating the partition wall 2 in a top view;
• 4 the heating element for heating the discharge opening 2 in a detailed three-dimensional representation. Parts that are identical or have a similar effect are provided with identical reference numbers where appropriate.

Individual technical features of the embodiments described below can also be combined with previously described embodiments as well as the features of the independent claims and any further claims 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 an inlet opening 11 and an outlet opening 12, wherein an exhaust gas flow S of the fuel cell system 2 can flow along a flow path in a main flow direction R from the inlet opening 11 to the outlet opening 12. The silencer 1 also has a silencer device 20 for reducing a noise of the exhaust gas flow S, wherein the silencer device 20 in the present case is designed as a reflection silencer with four silencer chambers 21a, 21b, 21c, 21d, through which a perforated pipe 22 extends and which are otherwise separated from one another by three partition walls 23a, 23b, 23c. Upstream of the silencer device 20, a water separator device 30 is arranged for separating water from the exhaust gas flow S, wherein the water separator device 30 has at least one water separator chamber 31. The silencer 1 also has a water collecting chamber 40 which partially surrounds the water separator chamber 31 and is in fluid communication with the water separator chamber 31 via a drain opening 41 such that water separated from the exhaust gas flow S can flow out of the water separator chamber 31, in particular independently due to gravity, into the water collecting chamber 40 and be collected there. The silencer 1 also has a heating device for heating at least part of a wall 43 delimiting the water collecting chamber 40, wherein the heating device in the present case has two heating elements 61, 62.

The exhaust gas stream S can be discharged 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 connection 16 of the silencer 1, into the silencer 1. 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.

The water separated in the water separation chamber 31 can flow through the drain opening 41 into the water collection chamber 40 due to gravity (gravity direction G) and be collected there. Additional openings 41a-c also allow condensed water to flow out of the soundproofing chambers 21a-d into the water collection chamber. Parts of the wall 43 delimiting the water collection chamber 40 can be heated by means of the heating device so that the separated or collected water does not freeze even at lower temperatures. The water collected in the water collection chamber 40 can be easily drained from the water collection chamber, e.g. via an outlet opening 42, actively - e.g. by a pump - or passively - e.g. independently 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 wall 43 delimiting the water collection chamber 40 forms a partition 44 between the water separation chamber 31 and the water collection chamber 40. The heating device has a heating element 61 for heating the partition 44, which in the present case essentially forms the entire partition 44. This ensures, among other things, that the drain opening 41 and the other openings 41a-c are sufficiently heated and cannot freeze even at very low ambient temperatures.

3 shows the heating element 61 for heating the partition wall 44. The sectional view of the heating element 61 in 2 corresponds to section II. The heating element 61 has two metallic electrodes 63a, 63b and a heating element 64 which is arranged at least partially between the electrodes 63a, 63b and contacts both electrodes 63a, 63b and functions as a heating resistor. The heating element 64 consists of a polymer-based material with a positive temperature coefficient. In this way, a self-regulating heating element 61 is created. This means that the heating element 61 can be directly contacted with a voltage source, e.g. a 12V or 24V vehicle battery, whereby a separate control and/or regulating device for regulating the heating output can be dispensed with. In the present case, the electrodes 63a, 63b are embedded in the heating element 64 to protect against corrosion.

As in 2 As can be seen, the heating element 61 for heating the partition wall 44 has a first surface 611 delimiting the water collecting chamber 40 and a second surface 612 delimiting the water separating chamber 31.

At the 2 In the embodiment of the silencer 1 according to the invention shown, the inner volume 10 of the silencer 1 formed by the water separation chamber 31 and the silencer chambers 21a, 21b, 21c, 21d extends along the longitudinal center axis A of the silencer 1 and rotationally symmetrical about the longitudinal center axis A. The inner volume 10 is essentially cylindrical. The water separation 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. To provide sufficient absorption capacity, the water collection chamber 40 extends essentially along the total length L of the inner volume 10.

The silencer 1 has a housing 13 which delimits a large part of the surface area of the cylindrical inner volume 10 and also a part of the water separation chamber 40. In other words, the housing 13 delimits a cavity within the silencer 1 which is formed by the water separation chamber 31, the sound damping chambers 21a, 21b, 21c, 21d and the water collection chamber 40. The housing 13 forms a receptacle for the partition wall 44 designed as a separate component, wherein the partition wall 44 received in the receptacle (e.g. inserted) separates the cavity in such a way that the water separation chamber 31 and the sound damping chambers 21a-d are on one side and the water collection chamber 40 is on the other side.

In the present case, the housing 13 also delimits an inlet-side front side of the cavity, while an outlet-side front side is delimited by a separate cover 15. The silencer 1 can be manufactured particularly easily in this way. For example, the silencer 1 can have a structure 14 that can be assembled from modules or formed as a single piece and 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. To manufacture the silencer, the partition wall 44 and the structure can thus be pushed into the housing 13 and the housing 13 can be closed with the cover 15.

The water collection chamber 40 has a discharge opening 42 through which collected water can be discharged from the silencer 1, in particular automatically due to gravity. The heating device has a heating element 62 for heating the discharge opening 42, which surrounds the discharge opening 42. The heating body 64 of the heating element 62 for heating the discharge opening 42 forms part of the wall 43a surrounding the discharge opening 42. In addition, the water collection chamber 40 has a discharge nozzle 45 protruding from the discharge opening 42, wherein the heating body 64 for heating the discharge opening 42 forms the discharge nozzle 45. In this way, sufficient heat input in the area of the discharge opening 42 and the discharge nozzle 45 is ensured. These components could otherwise become blocked due to their relatively small flow cross-section at ambient temperatures close to freezing point. The water collected in the water collecting chamber 40 can thus be reliably discharged from the silencer 1.

4 shows the heating element 62 for heating the discharge opening 42. The heating element 62 has two metallic electrodes 63a, 63b and a heating element 64 which is arranged at least partially between the electrodes 63a, 63b and contacts both electrodes 63a, 63b and functions as a heating resistor. The heating element 64 consists of a polymer-based material with a positive temperature coefficient. In this way, a self-regulating heating element 62 is created. As a result, the heating element 62 can be contacted directly with a voltage source, e.g. a 12V or 24V vehicle battery, whereby a separate control and/or regulating device for regulating the heating output can be dispensed with. In the present case, the electrodes 63a, 63b are embedded in the heating element 64 to protect against corrosion. The electrodes 63a, 63b each have a disc ring segment-shaped part 631a, 631b which extends around the discharge opening. The electrodes 63a, 63b also each have a plurality of fingers 632a, 632b that extend into the nozzle 45. In the present embodiment, the fingers 632a, 632b extend from the disk ring segment-shaped parts 631a, 631b. In this way, a particularly efficient heating of the area around the discharge opening 45 is possible.

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

Internal volume of the silencer

11

Inlet opening

12

Outlet opening

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

32

Impact element of the water separator

33

funnel-shaped guide element 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

Wall delimiting the water collecting chamber

43a

part of the wall surrounding the discharge opening

44

Partition wall between water collection chamber and water separation chamber

45

Discharge nozzle

61

Heating element for heating the partition wall

62

Heating element for heating the discharge opening

63a, 63b

Electrodes of the heating elements

631a, 631b

disc ring segment-shaped part of the electrodes

632a, 632b

Finger of the electrodes

64

Radiator of the heating elements

A

Longitudinal center axis of the silencer

G

Gravitational direction

L

Total length of the internal volume

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 for the better information of the reader. 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 (11)

Silencer (1) for an exhaust line of a fuel cell system (2) with an inlet opening (11) and an outlet opening (12), wherein an exhaust gas flow (S) of the fuel cell system (2) can flow along a flow path from the inlet opening (11) to the outlet opening (12), a sound-damping device (20) 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 separation device (30) arranged upstream of the sound-damping device (20) for separating water from the exhaust gas flow (S), wherein the water separation device (30) has at least one water separation chamber (31), a water collection chamber (40) which at least partially surrounds the water separation chamber (31) and which is connected to the water separation chamber via a drain opening (41) in such a way (31) is in fluid-conducting connection so 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, and a heating device for heating at least part of a wall (43) delimiting the water collection chamber (40), wherein the heating device has at least one heating element (61, 62). Silencer (1) after Claim 1 , wherein the at least one heating element (61, 62) has two metallic electrodes (63a, 63b) and a heating body (64) arranged at least partially between the electrodes (63a, 63b) and contacting both electrodes (63a, 63b), wherein the heating body (64) comprises a polymer-based material with a positive temperature coefficient. Silencer (1) after Claim 2 , wherein the electrodes (63a, 63b) are embedded in the heating body (64). Silencer (1) after Claim 2 or 3 , wherein the heating element (64) forms part of the wall (43) delimiting the water collecting chamber (40). Silencer (1) according to one of the Claims 2 until 4 , wherein the wall (43) delimiting the water collecting chamber (40) forms a partition wall (44) between the water separation chamber (31) and the water collecting chamber (40), wherein the heating device has a heating element (61) for heating the partition wall (44), which forms a part of the partition wall (44), preferably the predominant part of the partition wall (44). Silencer (1) after Claim 5 , wherein the heating element (61) for heating the partition wall (44) has a first surface (611) delimiting the water collecting chamber (40) and a second surface (612) delimiting the water separating chamber (31). Silencer (1) after Claim 5 or 6 with a housing (13) which delimits a cavity within the silencer (1) and forms a receptacle for the partition wall (44) designed as a separate component, wherein the partition wall (44) received in the receptacle separates the cavity at least into the water separation chamber (31) and the water receiving chamber (40). Silencer (1) according to one of the Claims 2 until 7 , wherein the water collecting chamber (40) has a discharge opening (42) through which collected water can be discharged from the silencer (1), in particular automatically due to gravity, wherein the heating device has a heating element (62) for heating the discharge opening (42), which heating element surrounds the discharge opening (42) at least partially, preferably completely. Silencer (1) after Claim 8 , wherein the heating body of the heating element (62) for heating the discharge opening (42) forms part of the wall (43a) surrounding the discharge opening (42). Silencer (1) after Claim 8 or 9 , wherein the water collecting chamber (40) has a discharge nozzle (45) protruding from the discharge opening (42), wherein the heating element (64) for heating the discharge opening (42) forms at least a part of the discharge nozzle (45). 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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