Heatable muffler for the exhaust gas section of a fuel cell system

Abstract

The invention relates to a muffler (1) for the exhaust gas section of a fuel cell system (2), comprising a muffler device (20) for reducing the sound of the exhaust gas flow (S), a water separating device (30) arranged upstream of the muffler device (20) for separating water from the exhaust gas flow (S), a water collecting chamber (40) which at least partly surrounds at least the water separating chamber (31), and which is fluidically connected to the water separating chamber (31) via a discharge opening (41) such that water separated from the exhaust gas flow (S) can flow out of the water separating chamber (31) and into the water collecting chamber (40) where the water can be collected, and a heating device for heating at least one part of a wall (43) which delimits the water collecting chamber (40).

Description

[0001] Description

[0002] Heatable silencer for an exhaust system of a fuel cell system

[0003] The present invention relates to a silencer for an exhaust system of a fuel cell system having the features of claim 1. Furthermore, the invention relates to a fuel cell system having the features of claim 11.

[0004] A fuel cell converts the chemical reaction energy of a continuously supplied fuel, e.g. hydrogen, and an oxidizing agent, e.g.

[0005] Oxygen, into electrical energy. Fuel cells are used, for example, in fuel cell vehicles to convert the generated electrical energy directly into motion using an electric drive or to temporarily store it in a drive battery. Fuel cells can also use other fuels besides hydrogen, particularly methanol, butane, or natural gas.

[0006] To supply the fuel and oxidizer, a fuel cell system uses several mechanical devices, which, during operation, generate noise that can be perceived as disturbing. To reduce the noise generated in the fuel cell system, silencers are installed within the fuel cell system, for example, in an exhaust system.

[0007] 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 tube extending through the chambers. The sound waves are reflected in the chambers. The coupling of the individual chambers creates so-called resonators in which the sound waves are reflected, partially canceling each other out according to the interference principle and thus being 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 tube. The greater the number of chambers present, the more efficient the damping is. An absorption silencer usually has only one chamber, through which a perforated tube runs. The chamber is lined with a sound-absorbing material, e.g.long-fiber mineral wool. The sound waves penetrate the perforated tube into the sound-absorbing material and are converted into heat through friction. The attenuation achieved depends on the material used, the packing density, the length, and the layer thickness of the chamber.

[0008] The exhaust gas produced during the power generation reaction in a hydrogen-oxygen fuel cell, which is primarily discharged from the fuel cell cathode, 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 excessively humid exhaust gas penetrates the muffler, the water vapor condenses, particularly on the muffler's surfaces, which negatively impacts the muffler's function - regardless of whether it is based on the reflection or absorption principle. In unfavorable cases, the moisture that accumulates in the muffler causes additional noise, which is perceived as unpleasant.

[0009] To counteract this problem, US 2013 175114 A1 proposes a hybrid silencer in which a dehumidification chamber, which is essentially completely filled with a water-absorbing material, is arranged upstream of a silencer device based on the reflection principle. However, to ensure a suitable dehumidification function, the dehumidification chamber must have a significantly larger volume than the silencer device. Nevertheless, the exhaust gas can only be dehumidified to a certain extent in the dehumidification chamber, so that the condensate that continues to form in the silencer device must be absorbed by a part of the water-absorbing material that projects into the silencer device. Furthermore, the water absorbed by the water-absorbing material cannot be easily drained away, but must usually 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 space and is complex to manufacture and operate.

[0010] In addition, the implementation of a separate dehumidification of the exhaust gas in the silencer poses 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 removal of the separated water from the silencer or, in the worst case, damage the silencer.

[0011] 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 noise associated with the operation of the fuel cell system can be achieved even at low ambient temperatures, while at least partially avoiding the disadvantages of the prior art. At the very least, an alternative to existing solutions is to be created. Furthermore, the object of the present invention is to provide a fuel cell system with such a silencer.

[0012] This object is achieved by a silencer having the features of claim 1 and a fuel cell system having 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.

[0013] 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 stream of the fuel cell system can flow along a flow path from the inlet opening to the outlet opening. The silencer further comprises a silencer device for reducing noise from the exhaust gas stream, 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 stream, wherein the water separation device has at least one water separation chamber.The silencer has a water collection chamber that at least partially surrounds the water separation chamber and is fluidly connected to the water separation chamber via a drain opening such 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 part of a wall delimiting the water collection chamber, wherein the heating device has at least one heating element.

[0014] The exhaust gas stream, which is, for example, discharged from the cathode of a fuel cell in the fuel cell system and fed directly or indirectly to the silencer, can flow through the cavity's inlet opening into the water separation chamber. In particular, the cavity's inlet opening simultaneously forms the inlet opening of the water separation chamber. In the water separation chamber, the exhaust gas stream is dehumidified, for example, by first expanding the exhaust gas stream through a baffle element and then narrowing it again through a funnel-shaped guide element arranged downstream, so that the exhaust gas stream is guided along the largest possible surface area, where the water contained in the exhaust gas can condense.

[0015] Depending on the installation position of the silencer, the condensed water collects due to gravity in a predetermined area of ​​the water separation chamber and can then easily drain away via the drain opening into the water collection chamber. In this way, the separated water is efficiently removed from the water separation chamber, preventing water from accumulating in the water separation device, which could otherwise have a negative impact on dehumidification. Furthermore, it prevents accumulated water from being transported by the exhaust gas flow towards the silencer and impairing its function. Reliable removal 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 easily be used, for example, in acan be actively discharged via a discharge opening - e.g. by a pump - or passively - e.g. automatically due to gravity - from the water collection chamber or from the silencer.

[0016] Since the water collection chamber is typically located away from the flow path for the warm exhaust stream, there is a risk that the collected water will freeze at ambient temperatures close to freezing, which can impair or prevent the separated water from being removed from the silencer. This risk is avoided by the heating device for heating at least part of a wall surrounding the water collection chamber.

[0017] 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.

[0018] A "water separation device" is a device primarily used to separate water (and / or another liquid) from the exhaust gas. A silencer device is therefore not considered a water separation device, even if some condensation and moisture removal also occurs in the silencer chamber.

[0019] The water collection chamber only needs to surround a small area of ​​the water separation chamber—e.g., an area located at the bottom with respect to the direction of gravity. The water collection chamber can therefore have a significantly smaller internal volume than the water separation chamber.

[0020] In a preferred embodiment of the silencer according to the invention, the water collection chamber further at least partially surrounds the silencer chamber and is fluidly connected to the silencer chamber via an opening such that water condensed from the exhaust stream can flow out of the silencer chamber into the water collection chamber, in particular independently due to gravity. In this way, the separated water is removed from the silencer chamber, preventing water from accumulating in the silencer device, which could otherwise have a negative impact on noise reduction. To avoid impairing its function, the opening for the condensed water is preferably located in a corner of the silencer chamber.Preferably, in the case of a plurality of adjacent sound-damping chambers separated by a partition wall, a common opening is arranged in the region of an end face of the partition wall, whereby condensed water from both sound-damping chambers can flow through the opening into the water collection chamber.

[0021] In a further preferred embodiment of the silencer according to the invention, the at least one heating element comprises two metallic electrodes and a heating element arranged at least partially between the electrodes and contacting both electrodes. The heating element comprises a polymer-based material with a positive temperature coefficient. The heating element is preferably made of the polymer-based material with a positive temperature coefficient.

[0022] 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 means in particular a material that is designed so 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, whereby the heater heats up to a material-specific maximum temperature. The heater therefore serves as a self-regulating heating resistor. In this way, the heating element can be connected directly to a voltage source, e.g.B. a 12V or 24V vehicle battery, whereby a separate control and / or regulating device for regulating the heating output as well as any temperature sensors required for recording the actual temperature can be dispensed with.

[0023] Various PTC materials based on (semi-)metals, ceramics, or polymers are known. One 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 comprises at least one polymer, wherein the material preferably comprises 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 assume a load-bearing and / or space-sealing function. The polymer-based material is also easy to process and can be seamlessly integrated into the other components of the silencer, which are preferably also made of a polymer material.

[0024] Furthermore, this eliminates the need for separate insulation of the heater to protect it from corrosion caused by contact with moist exhaust gases or water condensed from the exhaust gases. The heater can therefore 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 wherein the TP or TPE is mixed with conductive particles (e.g. soot or metal particles). Preferably, the material is 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 wherein the maximum operating temperature is between 50 °C and 60 °C.

[0025] In a further preferred embodiment of the silencer according to the invention, the electrodes of the heating element are embedded in the heater. In other words, the electrodes are completely surrounded by the polymer-based heater material on all sides, except for their electrical connection contacts. This encapsulates the electrodes, particularly to protect them from the warm, humid environment of the silencer. Furthermore, the heating output 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. The current initially flows directly from one electrode through the part of the heater between the electrodes to the other electrode.However, if the area of ​​the radiator between the electrodes has heated up to such an extent that its resistance increases by a certain amount, then the current also begins to flow through the adjacent areas of the radiator and thus heats them up.

[0026] 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 interior volume of the chamber. This ensures particularly efficient heat input into the water collection chamber. Furthermore, a compact design of the silencer is created because the heating element, in addition to its heating function, also has a load-bearing and / or space-enclosing function. The partition wall preferably comprises at least 50 vol.% of the polymer-based material with a positive temperature coefficient. Particularly preferably, the partition wall is made of the polymer-based material with a positive temperature coefficient.

[0027] 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. Furthermore, a certain amount of heat can be introduced in the region of the at least one drain opening in the partition, which could otherwise become blocked due to its relatively small flow cross-section at ambient temperatures close to freezing point.Particularly preferably, the heating element for heating the partition wall has a first surface delimiting the water collection chamber and a second surface delimiting the water separation chamber.

[0028] 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. inserted) separates the cavity at least into the water separation chamber and the water absorption chamber. Due to this structural design, the partition wall formed partially or completely by the radiator of the heating element can 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 polymeric material (e.g. polypropylene or another thermoplastic) and the partition wall (at least partially) from the polymer-based material with positive temperature coefficients.

[0029] 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 heating element at least partially, preferably completely, surrounds the discharge opening. In this way, sufficient heat input is ensured in the region 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, either actively - e.g. by a pump - or passively - e.g. automatically due to gravity.

[0030] 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 is delimited in the region of the discharge opening by a surface of the radiator 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, thereby minimizing the risk of the discharge opening freezing. 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 extending into the nozzle. In particular, the fingers extend from the disc-ring segment-shaped part(s).In this way, particularly efficient heating of the area around the discharge opening is possible.

[0031] Preferably, the water collection chamber extends along at least half the total length, preferably at least two-thirds of the total length, of an internal volume of the silencer formed by the water collection chamber and the silencer chamber(s). This enhances the absorption capacity of the water collection chamber. Furthermore, a compact design of the silencer can be realized.

[0032] 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 a section of the exhaust line can be attached.

[0033] Preferably, the housing consists of at least 50 vol.% of a material containing a thermoplastic. According to the above and further described below, the object stated above is also achieved by a fuel cell system having the features of claim 11.

[0034] The fuel cell system according to the invention comprises a fuel cell, an exhaust system leading from the fuel cell, and a silencer according to the invention installed in the exhaust system. The advantages of the silencer described above and below are thus realized for the fuel cell system.

[0035] It is expressly pointed out that the embodiments of the invention explained above can be combined individually or in any technically reasonable combination with each other with the subject matter of the independent claims.

[0036] 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:

[0037] Fig. 1 shows an embodiment of a fuel cell system according to the invention;

[0038] Fig. 2 shows a first embodiment of a silencer according to the invention in a sectional view;

[0039] Fig. 3 the heating element for heating the partition wall from Fig. 2 in a

[0040] top view;

[0041] Fig. 4 shows the heating element for heating the discharge opening from Fig. 2 in a detailed three-dimensional view. Parts with the same or similar functions are provided with identical reference numerals where appropriate.

[0042] Individual technical features of the exemplary embodiments described below can also be combined with previously described exemplary embodiments as well as the features of the independent claims and any further claims to form subject matter according to the invention.

[0043] Fig. 1 shows an embodiment of a fuel cell system 2 according to the invention. Hydrogen 5 and oxygen-containing air 6 are supplied to a fuel cell 3, in this case a hydrogen-oxygen fuel cell. A compressor is often used to supply the air 6, the operation of which is accompanied by considerable noise generation. A silencer 1 according to the invention is arranged in the exhaust system 4 of the fuel cell system 2. An exhaust gas supply line 4a conveys an exhaust gas stream 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 stream S away from the silencer 1—e.g., toward a tailpipe of the exhaust system 4.

[0044] Fig. 2 shows a first embodiment of a silencer 1 according to the invention for an exhaust system 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. Furthermore, the silencer 1 has a silencer device 20 for reducing 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 tube 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 separation device 30 is arranged for separating water from the exhaust gas stream S, wherein the water separation device 30 has at least one water separation chamber 31. The silencer 1 further has a water collection chamber 40 partially surrounding the water separation chamber 31, which is in fluid communication with the water separation chamber 31 via an outlet opening 41 such that water separated from the exhaust gas stream 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. The silencer 1 further has a heating device for heating at least part of a wall 43 delimiting the water collection chamber 40, wherein the heating device in the present case has two heating elements 61, 62.

[0045] The exhaust gas flow S can be guided from the fuel cell 3 into the silencer 1 via an exhaust gas feed line 4a (Fig. 1 ) of the exhaust system 4, which can be attached to the inlet nozzle 16 of the silencer 1. In the water separation chamber 31, the exhaust gas flow S is widened 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 thus guided along as large a surface 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 generation due to moisture accumulating in the silencer device 20 is avoided. The dehumidified and noise-free exhaust gas can be guided away from the silencer 1 via an exhaust gas discharge line 4b (Fig. 1) of the exhaust system 3, which can be attached to the outlet connection 17 of the silencer 1.

[0046] The water separated in the water separation chamber 31 can flow through the drain opening 41 due to gravity (gravity direction G) into the water collection chamber 40 and be collected there. Further openings 41a-c also allow condensed water from the soundproofing chambers 21a-d to flow into the water collection chamber. Parts of the wall 43 bordering 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.

[0047] The water collection chamber 40 need only surround a small area of ​​the water separation chamber 31—for example, a region located at the bottom with respect to the direction of gravity G, which, viewed from a direction parallel to the longitudinal center axis A, can be located approximately between a "5 o'clock position" and a "7 o'clock position." The water collection chamber 40 can thus have a significantly smaller internal volume than the water separation chamber 31.

[0048] The wall 43 defining 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 this case essentially forms the entire partition 44. This ensures, among other things, that the drain opening 41 and the other openings 41 ac are sufficiently heated and cannot freeze even at very low ambient temperatures.

[0049] Fig. 3 shows the heating element 61 for heating the partition wall 44. The sectional view of the heating element 61 in Fig. 2 corresponds to section II. The heating element 61 has two metallic electrodes 63a, 63b and a heater 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 heater 64 consists of a polymer-based material with a positive temperature coefficient. In this way, a self-regulating heating element 61 is created. As a result, the heating element 61 can be directly contacted with a voltage source, e.g., a 12V or 24V vehicle battery, eliminating the need for a separate control and / or regulating device for regulating the heating output. In the present case, the electrodes 63a, 63b are embedded in the heater 64 to protect against corrosion.

[0050] As can be seen in Fig. 2, the heating element 61 for heating the partition wall 44 has a first surface 611 defining the water collection chamber 40 and a second surface 612 defining the water separation chamber 31.

[0051] In the embodiment of the silencer 1 according to the invention shown in Fig. 2, the internal 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 internal volume 10 is essentially cylindrical. The water separation device 30 and the silencer device 20 are arranged centered to the longitudinal center axis A. This promotes a uniform and quiet flow of the exhaust gas stream, since in particular a change in the main flow direction R (flow reversal) is dispensed with. The advantageous flow behavior is also promoted by the fact that the inlet opening 11 and the outlet opening 12 are arranged centered to the longitudinal center axis A.To provide sufficient absorption capacity, the water collection chamber 40 extends substantially along the total length L of the internal volume 10.

[0052] The silencer 1 has a housing 13 which delimits a large part of the outer surface of the cylindrical inner volume 10 and additionally 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, 21b, 21c, 21d are located on one side and the water collection chamber 40 is located on the other side. In the present case, the housing 13 additionally delimits an inlet-side end face of the cavity, while an outlet-side end face 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, which can be inserted as a whole into the housing 13. The structure 14, together with the housing 13, forms the water separation device 30 and the silencer device 20. To manufacture the silencer, the partition wall 44 and the structure can thus be inserted into the housing 13, and the housing 13 can be closed with the cover 15.

[0053] 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 element 64 of the heating element 62 for heating the discharge opening 42 forms part of the wall 43a surrounding the discharge opening 42. Furthermore, the water collection chamber 40 has a discharge nozzle 45 protruding from the discharge opening 42, with the heating element 64 for heating the discharge opening 42 forming the discharge nozzle 45. In this way, sufficient heat input in the region of the discharge opening 42 and the discharge nozzle 45 is ensured. These components could otherwise become clogged 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.

[0054] Fig. 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 directly contacted with a voltage source, e.g., a 12V or 24V vehicle battery, eliminating the need for a separate control and / or regulating device for regulating the heating output. 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 further 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 disc-ring segment-shaped parts 631a, 631b. In this way, particularly efficient heating of the area around the discharge opening 45 is possible.

[0055] Additionally, 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 defined by the claims and is not limited by the features explained in the description or shown in the figures.

[0056]

[0057] 1 silencer

[0058] 2 Fuel cell system

[0059] 3 Fuel cell

[0060] 4 Exhaust system

[0061] 4a Exhaust gas supply line of the exhaust system

[0062] 4b Exhaust gas discharge of the exhaust system

[0063] 5 Hydrogen

[0064] 6 Air

[0065] 10 Internal volume of the silencer

[0066] 11 Inlet opening

[0067] 12 Outlet opening

[0068] 13 Silencer housing

[0069] 14 Structure of the silencer

[0070] 15 Silencer cover

[0071] 16 Silencer inlet port

[0072] 17 Exhaust port of the silencer

[0073] 20 Silencer silencer device

[0074] 21a-d Silencing chambers of the silencer device

[0075] 22 perforated pipe of the silencer device

[0076] 23a-c Partition walls of the silencer device

[0077] 30 Water separator

[0078] 31 Water separation chamber of the water separation device

[0079] 32 Impact element of the water separation device

[0080] 33 funnel-shaped guide element of the water separator

[0081] 35 wall defining the water separation chamber

[0082] 40 Water collection chamber of the silencer

[0083] 41 Drain opening of the water collection chamber

[0084] 41 ac openings of the water collection chamber

[0085] 42 Drain opening of the water collection chamber

[0086] 43 wall defining the water collection chamber

[0087] 43a part of the wall surrounding the discharge opening

[0088] 44 Partition wall between water collection chamber and water separation chamber

[0089] 45 discharge nozzles

[0090] 61 Heating element for heating the partition wall

[0091] 62 Heating element for heating the discharge opening 63a, 63b Electrodes of the heating elements

[0092] 631a, 631b disc-ring segment-shaped part of the electrodes

[0093] 632a, 632b Fingers of the electrodes

[0094] 64 radiators of the heating elements

[0095] A Longitudinal center axis of the silencer

[0096] G Direction of gravity

[0097] L Total length of the internal volume

[0098] R Main flow direction of the exhaust gas flow S Exhaust gas flow

Claims

Patent claims 1 . Silencer (1) for an exhaust system 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 silencer device (20) for reducing a noise of the exhaust gas flow (S), wherein the silencer device (20) has at least one silencer chamber (21a, 21b, 21c, 21d), a water separator device (30) arranged upstream of the silencer device (20) for separating water from the exhaust gas flow (S), wherein the water separator device (30) has at least one water separator chamber (31), a water collecting chamber (40) at least partially surrounding the water separator chamber (31) and connected via an outlet opening (41) to the Water separation chamber (31) is in fluid connection,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).

2. Silencer (1) according to claim 1, wherein the at least one heating element (61, 62) has two metallic electrodes (63a, 63b) and a heating element (64) arranged at least partially between the electrodes (63a, 63b) and contacting both electrodes (63a, 63b), wherein the heating element (64) has a polymer-based material with a positive temperature coefficient. Silencer (1) according to claim 2, wherein the electrodes (63a, 63b) are embedded in the heating element (64). Silencer (1) according to claim 2 or 3, wherein the heating element (64) forms part of the wall delimiting the water collecting chamber (40). (43). Silencer (1) according to one of claims 2 to 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 collection chamber (40), wherein the heating device comprises a heating element (61) for heating the partition wall (44), which forms part of the partition wall (44), preferably the majority of the partition wall (44). Silencer (1) according to claim 5, wherein the heating element (61) for heating the partition wall (44) has a first surface (611) delimiting the water collection chamber (40) and a second surface (612) delimiting the water separation chamber (31). Silencer (1) according to claim 5 or 6, comprising a housing (13) which defines a cavity within the silencer (1) and forms a receptacle for the partition wall (44) formed 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 claims 2 to 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) according to claim 8, wherein the heating element (62) for heating the discharge opening (42) forms part of the wall (43a) surrounding the discharge opening (42). Silencer (1) according to claim 8 or 9, wherein the water collection chamber (40) has a discharge nozzle (45) projecting from the discharge opening (42), wherein the heating element (64) for heating the discharge opening (42) forms at least 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) according to one of the preceding claims installed in the exhaust line (4).

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