Fuel cell exhaust gas system

Abstract

To extract water from fuel cell exhaust gas.SOLUTION: Provided is a fuel cell exhaust gas arrangement for a fuel cell system, in particular in a vehicle. The fuel cell exhaust gas arrangement includes a fuel cell exhaust gas line through which fuel cell exhaust gas can flow, and a muffler unit through which the fuel cell exhaust gas can flow. The muffler unit includes: a muffler housing; at least one muffler chamber formed in the muffler housing; and at least one liquid-collecting chamber which is separated from the at least one muffler chamber by a housing bottom of the muffler housing, in which at least one liquid-passage opening connecting the at least one muffler chamber to the at least one liquid-collecting chamber for exchanging liquid is provided, and in which at least one liquid-discharging opening for discharging liquid from the at least one liquid-collecting chamber is provided on the muffler housing.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a fuel cell exhaust gas device, via which process gas released from a fuel cell can be released into the environment as fuel cell exhaust gas. [Background technology]

[0002] It is known to use fuel cells, particularly in electric motor-driven vehicles, to provide energy for operating the electric traction motor and other consumers of electrical energy in such vehicles. During operation of such a fuel cell, hydrogen or a highly hydrogen-rich anode gas is supplied to the anode region. Oxygen or oxygen-containing air is supplied to the cathode region as the cathode gas. An electric current is generated while converting the hydrogen and oxygen into water. The hydrogen-rich anode exhaust gas and the highly water-containing cathode exhaust gas exit the fuel cell as fuel cell exhaust gas or process gas. During fuel cell operation, at least the cathode exhaust gas is released to the environment. During various operating phases, for example, especially during purging of the anode region before the start of fuel cell operation, the anode exhaust gas or gases guided through the anode region during such operating phases can also be released to the environment. Summary of the Invention [Problem to be solved by the invention]

[0003] The object of the present invention is to provide a fuel cell exhaust gas device for a fuel cell system, particularly in a vehicle, which is capable of extracting liquids, particularly water, entrained in the fuel cell exhaust gas from the fuel cell exhaust gas while attenuating noise generated during fuel cell operation. [Means for solving the problem]

[0004] According to the invention, the object is achieved by providing a fuel cell exhaust gas device for a fuel cell system, in particular in a vehicle, which comprises a fuel cell exhaust gas line through which the fuel cell exhaust gas can flow and a silencer unit through which the fuel cell exhaust gas can flow, the silencer unit comprising: a silencer housing having a fuel cell exhaust gas inlet area and a fuel cell exhaust gas outlet area, wherein an upstream pipe section of the fuel cell exhaust gas line is connected to the fuel cell exhaust gas inlet area and a downstream pipe section of the fuel cell exhaust gas line is connected to the fuel cell exhaust gas outlet area; at least one silencer chamber formed within a silencer housing; at least one liquid collecting chamber separated from the at least one silencer chamber by a housing bottom of the silencer housing, the housing bottom being provided with at least one liquid through opening connecting the at least one silencer chamber to the at least one liquid collecting chamber for liquid exchange, and the silencer housing being provided with at least one liquid outlet opening for leading liquid from the at least one liquid collecting chamber; The problem is solved by a fuel cell exhaust gas device comprising:

[0005] The silencer unit used in the fuel cell exhaust gas system constructed according to the present invention combines the function of damping noise generated during operation of the fuel cell system, particularly by an air compressor, for example, which compresses various gas streams, with the extraction of liquid, particularly water, contained in the fuel cell exhaust gas. This ensures that, on the one hand, the noise generated during operation of the fuel cell system is virtually unnoticeable or only strongly damped in the surroundings of the vehicle, while at the same time preventing the release of a fuel cell exhaust gas stream that is significantly rich in hot water or water vapor. The water extracted from the fuel cell exhaust gas in the area of ​​the silencer unit can be returned to the working circuit of the fuel cell system on demand or released in liquid form into the surroundings.

[0006] For effective sound attenuation, the silencer housing may include a plurality of silencer chambers separated from one another by separation walls, and each silencer chamber may be separated from at least one liquid collection chamber by a housing bottom, allowing each silencer chamber to discharge any liquid that collects therein.

[0007] In order to uniformly release the liquid from all the silencer chambers, the housing bottom may be provided with at least one liquid-through opening arranged corresponding to each silencer chamber.

[0008] In order to guide the fuel cell exhaust gas flow in a defined manner by the silencer housing or a silencer chamber formed therein, it is proposed that at least one fuel cell exhaust gas pipe is provided in the silencer housing, extending into the at least one silencer chamber, and that the at least one fuel cell exhaust gas pipe opens into the at least one silencer chamber, for example, via at least one opening, preferably a plurality of openings, formed in the pipe wall. For example, it may be provided that the at least one silencer chamber, together with the opening formed in the fuel cell exhaust gas pipe, forms a resonator chamber of a Helmholtz resonator.

[0009] To achieve a compact design that nevertheless generates the smallest possible flow resistance, it may be provided that the muffler housing is elongated in the direction of the longitudinal axis of the muffler housing, the fuel cell exhaust gas inlet area is formed in an upstream axial end area of ​​the muffler housing, and the fuel cell exhaust gas outlet area is formed in a downstream axial end area of ​​the muffler housing, so that the fuel cell exhaust gas can flow through the muffler unit in a substantially straight line without any substantial flow deflection.

[0010] The fuel cell exhaust gas inlet region may be open to an upstream silencer chamber, and the fuel cell exhaust gas outlet region may be open to a downstream silencer chamber, the upstream silencer chamber being separated from the downstream silencer chamber by at least one separating wall and / or at least one other silencer chamber.

[0011] To enhance the effect of separating the liquid from the fuel cell exhaust gas, it is proposed that a liquid separation chamber be formed in the silencer housing, the upstream pipe section of the fuel cell exhaust gas line be open to the liquid separation chamber, and the liquid separation chamber be separated from the silencer chamber by a separation wall. The liquid separation chamber may be separated from at least one liquid collection chamber by a housing bottom, which is provided with at least one liquid flow opening connecting the liquid separation chamber to the at least one liquid collection chamber for liquid exchange.

[0012] To separate the liquid from the fuel cell exhaust gas in the region of the liquid separation chamber, the upstream separation line section of the separation line section extending into the liquid separation chamber can be connected to the upstream line section of the fuel cell exhaust gas line in the fuel cell exhaust gas inlet region, and the downstream separation line section can pass through a separation wall separating the liquid separation chamber from the silencer chamber and / or open onto at least one silencer chamber. In the adjacent region between the downstream and upstream separation line sections, an opening region can be formed with a preferably substantially annular liquid separation opening that opens onto the liquid separation chamber.

[0013] In this opening region, the upstream end section of the downstream separation line section can be positioned in engagement with the downstream end section of the upstream separation line section such that a liquid separation opening is formed between the upstream end section of the downstream separation line section and the downstream end section of the upstream separation line section. For this purpose, for example, the downstream end section of the upstream separation line section can be configured to preferably widen substantially conically in the direction of the main exhaust gas flow and / or the upstream end section of the downstream separation line section can be configured to preferably widen substantially conically in the direction of the main exhaust gas flow.

[0014] In this configuration of the separation pipe section, it is proposed to provide a swirl generating unit upstream of the liquid separation opening so that the relatively high-density liquid can be collected in the radially outer region of the fuel cell exhaust gas flow relative to the flow axis and the radially outer liquid-rich portion of the fuel cell exhaust gas flow can then be led through the liquid separation opening into the liquid separation chamber. Such a swirl generating unit is used, for example, in the exhaust gas system of a diesel internal combustion engine, and can thereby generate swirls in the exhaust gas flow in the region upstream of the SCR catalyst unit, thereby improving mixing of the exhaust gas with the reducing agent injected into the exhaust gas.

[0015] Such a swirl generating unit may comprise a plurality of flow deflecting elements which are successively arranged in the circumferential direction about the central flow axis and angled with respect to the main exhaust gas flow direction.

[0016] The at least one liquid collection chamber may further include, for example: a liquid discharge valve for selectively opening and closing at least one liquid outlet opening; or / and a liquid level sensor for providing information regarding the liquid level in at least one liquid collection chamber; or / and a heating unit for heating the liquid collected in the at least one liquid collecting chamber; or / and at least one hydrogen release opening for releasing hydrogen from the at least one liquid collection chamber; may be provided.

[0017] The use of a liquid release valve allows the liquid collected in the at least one liquid collection chamber to be drained from the at least one liquid collection chamber and returned to the work process when a sufficient amount is present and when, for example, returning the liquid is necessary or advantageous during operation of the fuel cell system. Information regarding whether sufficient liquid has been collected or whether a large amount of liquid has already been collected that requires at least a portion of it to be drained from the liquid collection chamber can be provided by a liquid level sensor. The liquid collected in the at least one liquid collection chamber can be released even at relatively low temperatures, and to ensure that frozen liquid does not block the release, an electrically excitable heating unit, for example, equipped with a heating coil or the like, can be activated. Since the fuel cell exhaust gas may also contain hydrogen depending on which process gas stream is guided through the fuel cell exhaust gas device, the at least one hydrogen release opening allows for the hydrogen to be substantially continuously released to the environment to avoid the creation of dangerous hydrogen concentrations in the at least one liquid collection chamber.

[0018] A hydrogen sensor may be provided in the downstream section of the fuel cell exhaust gas line to provide information about the hydrogen content in the fuel cell exhaust gas. If an excessively high hydrogen concentration is detected in the fuel cell exhaust gas flowing through the downstream section of the line, an increased air proportion may be added to the fuel cell exhaust gas, thereby reducing the hydrogen concentration. Furthermore, a gas flow regulating valve may be provided in the upstream section of the line. This gas flow regulating valve may define and adjust the flow resistance in the fuel cell exhaust gas system, thereby fulfilling the function of a pressure-maintaining valve for maintaining or adjusting the back pressure required for the operation of the fuel cell system. Furthermore, this gas flow regulating valve may be configured to introduce various gas flows into the fuel cell exhaust gas system, for example, to introduce the cathode exhaust gas and / or anode exhaust gas of the fuel cell into the fuel cell exhaust gas system, or, if necessary, to introduce an additional air proportion required to reduce the hydrogen concentration.

[0019] To assist in the condensation of the liquid contained in the fuel cell exhaust gas, a condenser unit may be arranged in the upstream pipe section of the fuel cell exhaust gas line. In the condenser unit, the condensation of the liquid contained in the fuel cell exhaust gas can be induced, for example, by heat exchange between the fuel cell exhaust gas and the surrounding air, which is generally cooler than the fuel cell exhaust gas. It is also possible to use a liquid as a cooling medium. The heat absorbed in the liquid can be transferred, for example, in a heat exchanger, to the air to be introduced into the vehicle interior.

[0020] The present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a side view showing a fuel cell exhaust gas system. [Figure 2] 2 is a perspective side view of the fuel cell exhaust system shown in FIG. 1, with the silencer unit shown open; FIG. [Figure 3]1 is a side view of a fuel cell exhaust gas system, with the silencer unit shown open; FIG. [Figure 4] 2 is a side view showing a silencer unit of the fuel cell exhaust gas system shown in FIG. 1. FIG. [Figure 5] FIG. 2 is a side perspective view of the silencer unit, showing the silencer housing open. [Figure 6] FIG. 10 is a side view of the silencer unit, with the silencer housing shown open. [Figure 7] FIG. 2 is a perspective view showing a vortex generating unit. [Figure 8] FIG. 8 is an axial view of the vortex generating unit shown in FIG. 7. [Figure 9] 9 is a view corresponding to FIG. 8, showing an alternative configuration of the vortex generating unit. DETAILED DESCRIPTION OF THE INVENTION

[0022] 1 to 3 show a fuel cell exhaust gas device 10, which may be provided in correspondence with a fuel cell system used to generate electrical energy in a vehicle.

[0023] The fuel cell exhaust gas device 10 comprises a fuel cell exhaust gas line 12, generally designated by the reference numeral 12, through which a fuel cell exhaust gas B can flow, and a silencer unit 14 integrated into the fuel cell exhaust gas line 12. An upstream line section 16 of the fuel cell exhaust gas line 12 is connected to the silencer unit 14 in a fuel cell exhaust gas inlet region 18 of a silencer housing 20. A downstream line section 24 of the fuel cell exhaust gas line 12 is connected to the silencer unit 14 in a fuel cell exhaust gas outlet region 22 of the silencer housing 20. For example, the downstream line section 24 of the fuel cell exhaust gas line 12 can be used to discharge fuel cell exhaust gas B from one or more fuel cells of a fuel cell system into the environment. An upstream end region 26 of the upstream line section 16 of the fuel cell exhaust gas line 12 can be configured to be connected to a system region of one or more fuel cells or fuel cell stacks that discharge various fuel cell exhaust gases as process gases. For example, the anode region and / or cathode region of one or each fuel cell can be connected to the upstream end region so that the process gas leaving the anode region and / or the process gas leaving the cathode region can be defined as fuel cell exhaust gas B and introduced into the fuel cell exhaust gas device 10. Furthermore, ambient air can be introduced into the fuel cell exhaust gas device 10, for example, via a duct region open to the environment.

[0024] To regulate the back pressure created in the fuel cell exhaust gas system 10 or the gas flow introduced into the back pressure, a gas flow regulating valve 28 can be arranged, for example, near the upstream end region 26 of the pipe section 16 upstream of the fuel cell exhaust gas system 12. A hydrogen sensor 30 can be provided in the downstream pipe section 24, which can provide information about the hydrogen concentration of the fuel cell exhaust gas stream flowing through the downstream pipe section 24. If the anode region is purged at or before the start of fuel cell operation and the process gas derived from this anode region is released to the environment via the fuel cell exhaust gas system 10, this fuel cell exhaust gas stream may contain particularly hydrogen. If the signal generated by the hydrogen sensor 30 indicates an excessively high hydrogen concentration, for example, by correspondingly controlling the gas flow regulating valve 28, an air proportion or an increased air proportion can be added to the fuel cell exhaust gas B guided through the fuel cell exhaust gas system 10 via the aforementioned pipe section, thereby achieving a lower hydrogen concentration.

[0025] Upstream of the silencer unit 14 may be a condenser unit, generally designated by the reference numeral 31, which promotes condensation of liquids, typically water, carried in the fuel cell exhaust gas B. In the silencer unit 14, such condensed liquids may be withdrawn from the fuel cell exhaust gas B, collected, and returned to the fuel cell process, as described below.

[0026] The structure and function of the silencer unit 14 will be described in detail below with reference to FIGS.

[0027] The silencer housing 20 is elongated in the direction of the silencer housing longitudinal axis L and is configured at its upstream end region 32 to connect to the upstream pipe section 16 of the fuel cell exhaust gas line 12. At its downstream end region 34, the silencer housing 20 is configured to connect to the downstream pipe section 24 of the fuel cell exhaust gas line. For example, the pipe sections 16, 24 can be connected to corresponding pipe pieces of the silencer housing 20 using pipe clips or the like.

[0028] The silencer housing 20 defines two silencer chambers 36, 38 and a liquid separation chamber 40. The upstream silencer chamber 36 is separated from the liquid separation chamber 40 by a separation wall 42, and the downstream silencer chamber 38 is separated from the upstream silencer chamber 36 by a separation wall 44. The downstream line section 24 of the fuel cell exhaust gas line 12 opens to the downstream silencer chamber 38. The upstream line section 16 of the fuel cell exhaust gas line 12 opens to both silencer chambers 36, 38 via a separation line section 46 located in the liquid separation chamber 40.

[0029] The separation conduit section 46 has an upstream tubular separation conduit portion 48 that connects to the upstream conduit section 16 of the fuel cell exhaust conduit 12 at the upstream end region 32 of the silencer housing 20, and a downstream separation conduit portion 50 that connects to or passes through the separation wall 42. The downstream separation conduit portion 50 of the separation conduit section 46 may connect to or be integral with a fuel cell exhaust conduit 52 that is formed from one or more sections extending inside the silencer housing 12. The fuel cell exhaust conduit 52 opens into the upstream silencer chamber 36 via a plurality of openings 56 formed in a conduit wall 54 of the fuel cell exhaust conduit 52. The fuel cell exhaust conduit 52 opens into the downstream silencer chamber 38 via a plurality of openings 58 formed in the conduit wall 54. The fuel cell exhaust gas pipe 52 extends through the separating wall 44 separating the two muffler chambers 36, 38 from each other or may be at least partially formed integrally with this separating wall 44, and connects to the downstream pipe section 24 of the fuel cell exhaust gas pipe 12 in the downstream end region 34 of the muffler housing 20.

[0030] In this configuration, the fuel cell exhaust gas B guided through the silencer unit 14 can flow linearly through the silencer housing 20 along the silencer housing longitudinal axis L without substantially redirecting the flow, thereby preventing the silencer unit 14 from creating significant flow resistance. Nevertheless, sound can be attenuated by reflection and absorption due to communication between the different silencer chambers 36, 38. For this purpose, for example, an additional sound-absorbing material, such as a porous fiber material or a foam material, can be arranged in one or both silencer chambers 36, 38. Furthermore, more than two consecutive silencer chambers can be provided, or only one such silencer chamber can be provided within the interior of the silencer housing 20. Furthermore, at least one of the silencer chambers can function as a resonator chamber of a Helmholtz resonator, and different silencer chambers can be connected to each other via additional fuel cell exhaust gas pipes.

[0031] The upstream separation pipe section has a downstream end section 60 that is shaped to expand, for example, substantially conically, along the central flow axis S in the main exhaust gas flow direction H. Similarly, the downstream separation pipe section has an upstream end section 62 that is shaped to expand, for example, conically, in this region in the main exhaust gas flow direction H and is positioned to engage within the downstream end section 60 of the upstream separation pipe section 48. A substantially annular liquid separation opening 66 is formed in an opening region 64 of the separation pipe section 46 between the end sections 60, 62 that expand radially along the central flow axis S in the main exhaust gas flow direction H.

[0032] A vortex generating unit 68 is arranged upstream of the opening region 64, for example in the upstream separation pipe section 48 formed integrally with the housing cover that provides the upstream end wall of the silencer housing 20, or in the upstream pipe section 16 of the fuel cell exhaust gas pipe 12. The vortex generating unit 68 may include a plurality of flow deflection elements 69 that are successive in the circumferential direction about the central flow axis S and extend substantially radially and angled with respect to the main exhaust gas direction H. The vortex generating unit 68 generates vortices in the fuel cell exhaust gas B that is guided in the main exhaust gas direction H. Due to these vortices and the centrifugal forces generated within them, the liquid fraction carried in the fuel cell exhaust gas B, such as water droplets or the like, is forced radially outward, and the liquid concentrates in a higher concentration in the radially outer regions of the fuel cell exhaust gas flow. This radially outer portion of the fuel cell exhaust gas stream can be directed at least partially through the liquid separation opening 66 into the liquid separation chamber 40, thereby allowing liquid extracted from the fuel cell exhaust gas stream to collect within the liquid separation chamber 40.

[0033] In a fuel cell exhaust gas system 10 installed in a vehicle, a liquid collection chamber 70 is formed in a lower region of the silencer housing 20 in the vertical direction V. This liquid collection chamber 70 preferably extends along the entire length of the silencer housing 20, from the upstream end region 32 to the downstream end region 34 of the silencer housing 20, and is separated from the silencer chambers 36, 38 and from the liquid separation chamber 40 by a housing bottom 72. At least one liquid flow opening 74, 76, or 78 is formed in the housing bottom 72 corresponding to each of these chambers. Liquid collected in each of the silencer chambers 36, 38 or the liquid separation chamber 40 can reach and collect in the liquid collection chamber 40 through the corresponding liquid flow opening 74, 76, or 78.

[0034] At least one liquid outlet opening 80, which is provided with a liquid discharge valve 82, is arranged in correspondence with the liquid collection chamber 70. In Figures 1 to 6 it can be seen that in a fuel cell exhaust gas system installed in a vehicle, the silencer housing 20 is tilted downwards in the main exhaust gas direction H, so that the area of ​​the liquid collection chamber 70 in which the liquid outlet opening 80 is located essentially forms the lowest area of ​​the liquid collection chamber 70 in the vertical direction V. This means that the liquid contained in the liquid collection chamber 70 essentially collects in the area of ​​the liquid outlet opening 80 or the liquid discharge valve 82, so that when the liquid discharge valve 82 is opened, the liquid flows out of the liquid collection chamber 70 under the action of gravity and can, for example, be returned to the fuel cell process or discharged in liquid form to the surroundings.

[0035] A liquid level sensor 84, shown in principle in Fig. 6, may be provided in correspondence with the liquid collection chamber 70, the output signal of which indicates the amount of liquid collected in the liquid collection chamber 70. If this amount is large enough that the liquid, i.e., water, can be used during fuel cell operation, the liquid discharge valve 82 can be opened. If a threshold level is exceeded and there is a risk that liquid can no longer flow into the liquid collection chamber 70 from at least the lowest region of the downstream muffler chamber 38, the liquid outlet valve 82 can also be opened to discharge the liquid from the liquid collection chamber 70.

[0036] Furthermore, a heating unit 86, which is shown in principle in Fig. 6, can be assigned to the liquid collection chamber 70. By electrical excitation, this heating unit 86 can heat the liquid collected in the liquid collection chamber 70 and thus prevent the liquid from freezing or re-thaw already frozen liquid. This ensures that the liquid can be released from the liquid collection chamber 70 at any time, and in particular at relatively low ambient temperatures, so that it can be reused, for example, during fuel cell operation.

[0037] Furthermore, at least one hydrogen release opening 90 provided by the hydrogen release pipe piece 88 may be provided corresponding to the liquid collection chamber 70. This hydrogen release opening 90 may be positioned higher in the vertical direction V than the highest region of the liquid collection chamber 70. Therefore, when hydrogen introduced into the fuel cell exhaust gas system 10 during fuel cell operation or purging of the anode region reaches the liquid collection chamber 70 through the liquid flow openings 74, 76, 78, it can collect in the highest region of the liquid collection chamber 70 where the liquid collection chamber 70 opens to the periphery through the hydrogen release opening 90. Therefore, hydrogen that reaches the liquid collection chamber 70 can be substantially permanently released to the periphery without the risk of a dangerous hydrogen concentration forming in the liquid collection chamber 70.

[0038] 7 to 9 show in more detail an embodiment of a vortex generating unit 68 that can be used in the fuel cell exhaust gas system 10. The vortex generating unit 68 may be formed, for example, from a single piece of sheet metal and includes an annular or substantially cylindrical body 88, by which the vortex generating unit 68 can be held, for example, in the upstream separation pipe section 48. Starting from the body 68, blade-like flow deflecting elements 69 extend radially inward, arranged consecutively in the circumferential direction, so that the flow deflecting elements 69 partially overlap in the circumferential direction, for example, in their radially inner end regions. The flow deflecting elements 69 are angled with respect to the main exhaust gas flow direction H, i.e., inclined at an angle other than 90°. As a result, the fuel cell exhaust gas B flowing in the main exhaust gas flow direction H toward the vortex generating unit 68 is deflected in the circumferential direction with respect to the central flow axis S by the flow deflecting elements 69, generating vortices.

[0039] In an alternative configuration, the vortex generating unit 68 may be formed as a plastic part, which provides a lightweight, inexpensive to manufacture, and corrosion-resistant structure, and allows for greater design freedom in the construction of the vortex generating unit 68.

[0040] It is further suggested that other system areas or components of the fuel cell exhaust gas system 10, such as the fuel cell exhaust gas line 12 and the silencer unit 14, may also be constructed substantially entirely from plastic materials, resulting in a structure of the fuel cell exhaust gas system 10 that is easy and inexpensive to manufacture and that is corrosion-resistant, particularly with respect to the water contained in the fuel cell exhaust gas B.

[0041] The degree of deflection in the circumferential direction, and thus the degree of vortex generation, and simultaneously the degree of flow interruption caused by the flow deflection element 69, also depend on the inclination angle of the flow deflection element 69 with respect to the main exhaust gas flow direction H. In the embodiments shown in Figures 7 and 8, the flow deflection elements 69 are angled relatively small, i.e., oriented more in the direction of the main exhaust gas flow direction H, resulting in a less significant deflection of the fuel cell exhaust gas flow in the circumferential direction. Figure 9 shows a configuration of the vortex generating unit 68 in which the flow deflection elements 69, which are further enlarged in the circumferential direction, are angled more strongly with respect to the main exhaust gas flow direction. The configuration of the vortex generating unit 68 shown in Figure 9 results in a relatively large deflection of the fuel cell exhaust gas flow in the circumferential direction, which contributes to increasing the centrifugal force acting on the liquid particles contained in the fuel cell exhaust gas.

[0042] The fuel cell exhaust gas system according to the present invention integrates advantageous or important functions for the operation of the fuel cell exhaust gas system or for the operation of a fuel cell system in a vehicle. On the one hand, the silencing function of the silencer unit reduces or almost completely eliminates noise generated in the fuel cell exhaust gas flow path, for example, by a compressor guiding process gas through the fuel cell. On the other hand, liquids, particularly water, entrained in the fuel cell exhaust gas can be extracted from the fuel cell exhaust gas, so that this water can be returned to the working cycle of the fuel cell system as needed, rather than being discharged into the environment. Water separated from the fuel cell exhaust gas that cannot be used in the fuel cell process can be discharged in liquid form into the environment. The generation of dangerous hydrogen concentrations, particularly in the area of ​​the silencer unit, is avoided by the permanent possibility of releasing hydrogen into the environment. This functionality is also due in particular to the fact that the fuel cell exhaust gas can flow through the silencer unit in an approximately straight line. In particular, sharp angles of the pipe sections guiding the fuel cell exhaust gas inside the silencer unit and the resulting flow deflections are avoided. Since water or water vapor and hydrogen can be extracted from the fuel cell exhaust gas during operation of the fuel cell system and, if necessary, can also be returned to the fuel cell process, it is possible to largely prevent such substances from being supplied to the vehicle's surroundings. It should be further emphasized that such a fuel cell exhaust gas device can be used, for example, in fuel cell systems operating stationary, as well as in fuel cell systems operating, for example, on ships or the like.

Claims

1. A fuel cell exhaust gas device for a fuel cell system, comprising: a fuel cell exhaust gas pipe (12) through which a fuel cell exhaust gas (B) can flow; and a silencer unit (14) through which the fuel cell exhaust gas (B) can flow, wherein the silencer unit (14) a silencer housing (20) with a fuel cell exhaust gas inlet area (18) and a fuel cell exhaust gas outlet area (22), in which an upstream pipe section (16) of the fuel cell exhaust gas line (12) is connected to the fuel cell exhaust gas inlet area (18) and a downstream pipe section (24) of the fuel cell exhaust gas line (12) is connected to the fuel cell exhaust gas outlet area (22); - at least one silencer chamber (36, 38) formed in said silencer housing (20); at least one liquid collection chamber (70) separated from at least one silencer chamber (36, 38) by a housing bottom (72) of said silencer housing (20), said silencer housing (20) being provided with at least one liquid outlet opening (80) for outlet of liquid from said at least one liquid collection chamber (70); In a fuel cell exhaust gas system, a housing bottom (72) having at least one liquid flow opening (74, 76) for connecting at least one silencer chamber (36, 38) to at least one liquid collection chamber (70) for liquid exchange; a liquid separation chamber (40) formed in the silencer housing (20); the upstream pipe section (16) of the fuel cell exhaust gas line (12) is open to the liquid separation chamber (40); the liquid separation chamber (40) is separated from the silencer chamber (36) by a separation wall (42); the liquid separation chamber (40) is separated from the at least one liquid collection chamber (70) by the housing bottom (72); and the housing bottom (72) having at least one liquid flow opening (78) for connecting the liquid separation chamber (40) to the at least one liquid collection chamber (70) for liquid exchange.

2. 2. The fuel cell exhaust gas system of claim 1, wherein a plurality of silencer chambers (36, 38) are formed in the silencer housing (20), each separated from one another by a separation wall (44), and each silencer chamber (36, 38) is separated from the at least one liquid collection chamber (70) by the housing bottom (72).

3. 3. The fuel cell exhaust gas system according to claim 2, wherein the housing bottom (72) is provided with at least one liquid passage opening (74, 76) corresponding to each silencer chamber (36, 38).

4. 4. The fuel cell exhaust gas system according to claim 1, wherein the muffler housing includes at least one fuel cell exhaust gas pipe extending into the at least one muffler chamber, the at least one fuel cell exhaust gas pipe opening into the at least one muffler chamber through at least one opening.

5. 5. The fuel cell exhaust system of claim 4, wherein the at least one fuel cell exhaust pipe (52) opens into the at least one silencer chamber (36, 38) via at least a plurality of openings (56, 58).

6. 4. The fuel cell exhaust gas device according to claim 1, wherein the silencer housing (20) is elongated in the direction of the silencer housing longitudinal axis (L), the fuel cell exhaust gas inlet region (18) is formed in an upstream axial end region (32) of the silencer housing (20), and the fuel cell exhaust gas outlet region (22) is formed in a downstream axial end region (34) of the silencer housing (20).

7. 4. The fuel cell exhaust gas system according to claim 1, wherein the fuel cell exhaust gas inlet region (18) is open to an upstream silencer chamber (36), the fuel cell exhaust gas outlet region (22) is open to a downstream silencer chamber (38), and the upstream silencer chamber (36) is separated from the downstream silencer chamber (38) by at least one separating wall (44) and / or at least one further silencer chamber.

8. A fuel cell exhaust gas device as described in any one of claims 1 to 3, wherein a liquid discharge valve (82) is provided corresponding to the at least one liquid collection chamber (70) for selectively opening and closing the at least one liquid discharge opening (80).

9. 4. The fuel cell exhaust gas system according to claim 1, wherein an upstream separation line section (48) of the separation line section (46) extending into the liquid separation chamber (40) connects to the upstream line section (16) of the fuel cell exhaust gas line (12) in the fuel cell exhaust gas inlet region (18), and a downstream separation line section (50) penetrates a separation wall (42) separating the liquid separation chamber (40) from a silencer chamber (36) and / or opens into at least one silencer chamber (36, 38), and an opening region (64) with a liquid separation opening (66) opening into the liquid separation chamber (40) is formed in an adjacent region between the downstream separation line section (50) and the upstream separation line section (48).

10. 10. The fuel cell exhaust gas system of claim 9, wherein the liquid separation opening (66) is annular.

11. 10. The fuel cell exhaust gas system of claim 9, wherein the upstream end section (62) of the downstream separation line section (50) is engaged and positioned within the downstream end section (60) of the upstream separation line section (48) in the opening region (64) so ​​that the liquid separation opening (66) is formed between the upstream end section (62) of the downstream separation line section (50) and the downstream end section (60) of the upstream separation line section (48).

12. 12. The fuel cell exhaust gas system according to claim 11, wherein the downstream end section (60) of the upstream separation pipe section (48) is configured to expand in the main exhaust gas flow direction (H) and / or the upstream end section (62) of the downstream separation pipe section (50) is configured to expand in the main exhaust gas flow direction (H).

13. 13. The fuel cell exhaust gas system according to claim 12, wherein the downstream end section (60) of the upstream separation line section (48) is configured to expand conically in the main exhaust gas flow direction (H) and / or the upstream end section (62) of the downstream separation line section (50) is configured to expand conically in the main exhaust gas flow direction (H).

14. 10. The fuel cell exhaust gas system of claim 9, further comprising a vortex generating unit (68) upstream of the liquid separation opening (66).

15. 15. The fuel cell exhaust gas system according to claim 14, wherein the vortex generating unit (68) comprises a plurality of flow deflection elements (69) arranged circumferentially successively about the central flow axis (S) and angled with respect to the main exhaust gas flow direction.

16. Corresponding to said at least one liquid collection chamber (70), a liquid level sensor (84) for providing information about the liquid level in said at least one liquid collection chamber (70); or / and a heating unit (86) for heating the liquid collected in said at least one liquid collecting chamber (70); or / and at least one hydrogen release opening (90) for releasing hydrogen from said at least one liquid collection chamber (70); 4. The fuel cell exhaust gas system according to claim 1, further comprising:

17. 4. The fuel cell exhaust gas system according to claim 1, wherein a hydrogen sensor is provided in the downstream pipe section of the fuel cell exhaust gas line for providing information about the hydrogen content in the fuel cell exhaust gas.

18. 4. The fuel cell exhaust gas system according to claim 1, wherein a gas flow regulating valve (28) is arranged in the upstream pipe section (16) and / or a condenser unit (31) is arranged in the upstream pipe section (16) of the fuel cell exhaust gas line (12).

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