Purge assembly for an anode subsystem, fuel cell system, and vehicle

Abstract

The invention relates to a purge assembly (10) for an anode subsystem (11) of a fuel cell system (12), having an anode exhaust gas line (13) for conducting anode exhaust gas (20) out of the anode subsystem (11) and into an exhaust gas collecting line (21) of the fuel cell system (12), a buffering means (14) which is positioned in the anode exhaust gas line for buffering an anode exhaust gas flow in the anode exhaust gas line (13), and a bypass (15) in the anode exhaust gas line (13) for conducting the anode exhaust gas (20) past the buffering means (14). The invention additionally relates to a fuel cell system (12) comprising the purge assembly (10) and to a vehicle (100) comprising the fuel cell system (12).

Description

[0001] Description

[0002] Purging arrangement for an anode subsystem, fuel cell system and vehicle

[0003] The present invention relates to a purge assembly for an anode subsystem of a fuel cell system. The invention further relates to a fuel cell system having the purge assembly and a vehicle having the fuel cell system.

[0004] Known fuel cell systems typically comprise a fuel cell stack with a cathode and an anode, a cathode inlet path for conducting oxidant into the cathode, a cathode outlet path for conducting cathode exhaust gas from the cathode, an anode inlet path for conducting fuel into the anode, and an anode outlet path for conducting anode exhaust gas from the anode. Furthermore, fuel cell systems are known to comprise a collective exhaust path through which the cathode exhaust gas and the anode exhaust gas can be discharged together into the environment of the fuel cell system.

[0005] Due to various diffusion mechanisms, gases between the anode and cathode of the fuel cell stack can pass through a membrane arrangement positioned between the anode and cathode. Therefore, in known systems, for example, in a water separator and / or a cyclone separator of an anode subsystem, liquid water is separated from gases such as oxygen, nitrogen, and hydrogen. The gases and liquids are then conducted, together with cathode exhaust, via the collective exhaust line into the environment of the fuel cell system. The purged anode exhaust may contain fuel, which can lead to the local formation of a potentially unfavorable gas mixture in the collective exhaust. For particularly advantageous operation of the fuel cell system, the fuel concentration of the anode exhaust and / or the collective exhaust discharged from the fuel cell system into the environment should be as low as possible.The object of the present invention is to provide devices for safely conducting anode exhaust gas and / or collective exhaust gas into the environment of a fuel cell system.

[0006] The above object is achieved by the patent claims. In particular, the above object is achieved by the purging arrangement according to claim 1, as well as by the fuel cell system and the vehicle according to the dependent claims. Further advantages of the invention emerge from the subclaims, the description, and the figures. Features described in connection with the purging arrangement also apply in connection with the fuel cell system according to the invention, the vehicle according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is and / or can always be made to each other.

[0007] According to a first aspect of the present technology, a purge assembly for an anode subsystem of a fuel cell system is proposed. The purge assembly comprises an anode exhaust line for conducting or purging anode exhaust from the anode subsystem into a collecting exhaust line of the fuel cell system, a buffer means positioned in the anode exhaust line for buffering fuel from the anode exhaust, and a bypass in the anode exhaust line for conducting the anode exhaust past the buffer means.

[0008] In a purging arrangement according to the present technology, the anode exhaust gas is not fed directly into the cathode exhaust gas, but can first be fed into the buffer medium. Using the buffer medium, fuel-containing anode exhaust gas can be introduced into the exhaust stream at a reduced volume flow. In other words, the fuel-containing anode exhaust gas is not introduced abruptly into the exhaust stream in this case. This allows the anode exhaust gas to mix better and more evenly with the cathode exhaust gas. Consequently, the fuel concentration in the collective exhaust gas can be reduced. The purging process performed in this case, or so-called purging, is not carried out continuously. This means that the anode exhaust gas line conducting anode exhaust gas from the anode is not continuously open. Rather, purging can be carried out by an anode purge valve for a specific and / or determinable time.For this reason, a type of gas cloud with a high fuel concentration is regularly flushed out, which is to be diluted in the proposed manner. The buffering agent can be understood as a storage means for temporarily storing and / or retaining at least a portion of the anode exhaust gas in the anode exhaust gas line. Buffering can therefore be understood as delaying and / or slowing down the anode exhaust gas flow in the anode exhaust gas line and / or temporarily reducing the anode exhaust gas volume flow in the anode exhaust gas line.

[0009] The bypass can comprise a bypass line past the buffer means and at least one bypass valve positioned in the bypass line. The at least one bypass valve can be understood as a unit for controlling and / or regulating an anode exhaust gas flow through the bypass line. The bypass line can have a smaller line diameter than the anode exhaust gas line. The at least one bypass valve can therefore be designed as a controllable and / or regulatable bypass valve, in particular as an electrically controllable and / or electrically regulatable bypass valve. The bypass is preferably configured to guide the anode exhaust gas past the buffer means and subsequently into the cathode exhaust gas line, in particular directly into the cathode exhaust gas line.The section in which the bypass and / or the bypass line of the bypass leads into the cathode exhaust line can also be understood as a collecting section, in which the cathode exhaust line and the anode exhaust line merge and continue as a collecting exhaust line. The fact that the bypass and the buffer means are positioned in the anode exhaust line can be understood as meaning that the bypass and the buffer means are configured and designed as part of the anode exhaust line.

[0010] According to a further embodiment of the present technology, it is possible for the buffering agent to comprise porous material for buffering the anode exhaust gas stream. By using porous material, the desired buffering effect can be achieved simply and reliably. Furthermore, the buffering agent can be provided in a compact and mechanically stable manner using porous material. A further advantage of using porous material is that it hardly freezes or does not freeze. This is particularly advantageous for a cold start of the fuel cell system. A porous material can be understood to be a substance or object that has small holes or cavities that can fill with anode exhaust gas. These cavities nevertheless enable the anode exhaust gas to be transported through the material.The porous material has a relatively large surface area compared to its volume and has a relatively low density, in particular a density lower than 1000 kg / m. 3 or lower than 500 kg / m 3 is.

[0011] Nevertheless, it is important to ensure that the material density is sufficiently high to create a sufficiently high flow resistance or fuel front, while also preventing blockage of the anode exhaust line. The buffer material can also be configured and / or designed to minimize chemical reaction with hydrogen, to be thermally stable when used in the anode subsystem, and to prevent metal fire.

[0012] Furthermore, in a purge arrangement according to the present technology, it is possible for the buffering agent to comprise a fabric and / or fiber material for buffering the anode exhaust gas stream. Such a buffering agent has proven particularly effective in tests within the scope of the present invention. For example, the buffering agent may comprise nylon threads, a nylon fabric, and / or a porous nylon structure.

[0013] Furthermore, a flushing arrangement according to the present technology can comprise a housing, wherein the buffer means and the bypass are positioned within this housing. This means that the buffer means and the bypass can be configured and designed such that they are integrated into the same housing. In this way, the flushing arrangement can be provided in a particularly compact and robust manner.

[0014] Furthermore, according to the present technology, it is possible for the purging arrangement to have a mixing region that is designed or formed downstream of the buffering agent and upstream of the collecting exhaust line for mixing buffered anode exhaust gas with cathode exhaust gas. The mixing region can be formed in an open region of the housing and, in the fuel cell system, can be located directly adjacent to the cathode exhaust line and / or within the cathode exhaust line. In this way, the anode exhaust gas collected or buffered in the buffering agent can be purged by the cathode exhaust gas from the buffering agent, for example, from the porous structure of the buffering agent. This allows the desired mixing of the anode exhaust gas with the cathode exhaust gas and the conveying of the anode exhaust gas through the buffering agent to be achieved particularly simply and energy-efficiently.An interface between the mixing region and the cathode exhaust line and / or between the buffer agent and the cathode exhaust line can have a larger area than a cross-section of the anode exhaust line and / or than a cross-section of the cathode exhaust line. Furthermore, the interface between the mixing region and the cathode exhaust line and / or the interface between the buffer agent and the cathode exhaust line can have a greater length and / or a larger diameter than a cross-section of the anode exhaust line and / or than a cross-section of the cathode exhaust line. This allows for particularly effective mixing of the cathode exhaust gas with the anode exhaust gas.

[0015] Another aspect of the present technology relates to a fuel cell system comprising a fuel cell stack, a cathode subsystem with a cathode exhaust line, and an anode subsystem with an anode exhaust line and a purge assembly as described above. Thus, the fuel cell system provides the same advantages as described in detail with reference to the purge assembly.

[0016] The fuel cell system is preferably configured for mobile applications such as vehicles, in particular for providing energy for at least one drive unit, such as an electric motor, to propel the vehicle. In its simplest form, a fuel cell is an electrochemical energy converter that converts fuel and oxidant into reaction products, thereby producing electricity and heat. The fuel cell comprises an anode and a cathode separated from each other by an ion-selective or ion-permeable separator. The anode can be supplied with fuel.

[0017] Preferred fuels are hydrogen, low-molecular-weight alcohol, biofuels, or liquefied natural gas. The cathode can be supplied with an oxidizing agent. Preferred oxidizing agents are air, oxygen, and peroxides. An ion-selective separator between the anode and the cathode can be designed as a proton exchange membrane. The fuel cell system preferably comprises a fuel cell stack with several stacked fuel cells. The anode can be understood here as an anode section with several positively charged electrodes. The cathode can be understood here as a cathode section with several negatively charged electrodes.

[0018] The fuel cell system may include an anode purge valve for directing or purging the anode exhaust gas from the anode subsystem. An anode purge valve is also referred to as a purge valve. By repeatedly opening and closing the anode purge valve, anode exhaust gases can be diverted from a recirculation path of the anode subsystem and introduced via the further course of the anode exhaust line into the cathode exhaust line and finally into the collective exhaust line. The anode purge valve may be positioned in a water separator, on a water separator, or downstream of a water separator. The anode purge valve may be configured as an electromagnetic valve. The anode subsystem may include the fuel-carrying components of the fuel cell system.An anode subsystem may include at least one pressure vessel, at least one tank shutoff valve, at least one pressure reducer, at least one anode supply path leading to the anode inlet of the fuel cell stack, an anode chamber in the fuel cell stack, at least one recirculation supply path leading away from the anode outlet of the fuel cell stack, at least one water separator, at least one anode purge valve, at least one active or passive fuel recirculation promoter, for example in the form of a blower or a suction jet pump, and other elements. The main function of the anode subsystem is to supply and distribute fuel to the electrochemically active surfaces of the anode and to remove anode exhaust gas from the anode.

[0019] The fuel cell system further comprises a cathode subsystem. The cathode subsystem is formed from the oxidant-carrying components. A cathode subsystem can have at least one oxidant feeder, at least one cathode supply path leading to the cathode inlet, at least one cathode exhaust line leading away from the cathode outlet, a cathode compartment in the fuel cell stack, and other elements. The main function of the cathode subsystem is to supply and distribute oxidant to the electrochemically active surfaces of the cathode compartment and to remove unused oxidant from the cathode.

[0020] According to a further embodiment of the present technology, it is possible for the mixing area for mixing the buffered anode exhaust gas with the cathode exhaust gas to be positioned directly on the cathode exhaust gas line and / or directly on the collecting exhaust gas line. As already described above, in this way, the anode exhaust gas collected or buffered in the buffer medium can be flushed out of the buffer medium particularly effectively and efficiently by the cathode exhaust gas.

[0021] Furthermore, according to the present technology, it is possible for the fuel cell system to have a fuel sensor downstream of the mixing region in the collective exhaust line for determining a fuel concentration in the collective exhaust line, and a controller for controlling the bypass depending on the determined fuel concentration in the collective exhaust line. In this way, the desired mixing can be adapted to the respective operating state of the fuel cell system in a simple and automated manner. Furthermore, the operational reliability of the fuel cell system can be ensured in that separated water from the anode, which can freeze in the buffer medium, does not lead to a blockage or partial blockage of the anode exhaust line. In this case, the controller can be understood, for example, as a control unit such as a vehicle control unit or at least a part thereof.Determining the fuel concentration can be understood to mean that the fuel concentration is determined using the fuel sensor, directly or indirectly. The fuel concentration can be determined by measuring a sensor value using the fuel sensor, based on which the fuel concentration is calculated. The fuel sensor can be understood to mean any type of sensor by means of which actual, calculated and / or estimated measured values ​​can be obtained in the collective exhaust gas, based on which the fuel concentration can be determined, calculated and / or estimated. The fuel sensor is in signal communication with the controller for transmitting the determined sensor values. The controller is configured to control the bypass and in particular a bypass valve in a bypass line of the bypass based on the received sensor data.In addition, calculations can be performed in the controller based on the sensor data. The controller can also be connected to other functional components of the fuel cell system shown; however, a complete wiring and / or connection diagram has been omitted for clarity. Furthermore, it is possible that the controller, the fuel sensor, and other functional components of the fuel cell system transmit and / or receive signals wirelessly, instead of wired.

[0022] Additionally or alternatively, it is possible for a fuel cell system according to the present technology to have a fuel sensor upstream of the mixing region in the anode exhaust line for determining a fuel concentration in the anode exhaust line and a controller for controlling the bypass depending on the determined fuel concentration in the anode exhaust line. This allows the fuel cell system, and in particular the purging device, to be operated even more reliably with regard to the desired mixing.

[0023] Furthermore, one aspect of the present technology relates to a vehicle having a fuel cell system as described above and at least one electric motor for driving the electric vehicle, wherein the fuel cell system is configured to supply power to the at least one electric motor. The vehicle thus offers the same advantages as have been described in detail with reference to the fuel cell system. The vehicle can be understood to mean a motor vehicle such as a motor-driven two-wheeler, a car, or a truck. The vehicle can also be understood to mean a road vehicle, an aircraft, a watercraft, a rail vehicle, a spacecraft, or a robot. The vehicle can also be understood to mean a purely electric vehicle or a hybrid electric vehicle, which, in addition to the at least one electric motor, has an internal combustion engine for driving the vehicle.

[0024] Further measures improving the invention will become apparent from the following description of various exemplary embodiments of the invention, which are schematically illustrated in the figures. All features and / or advantages apparent from the claims, the description, or the figures, including structural details and spatial arrangements, may be essential to the invention both individually and in various combinations.

[0025] They show schematically:

[0026] Fig. 1 shows a fuel cell system according to an embodiment of the present technology,

[0027] Fig. 2 shows a flushing arrangement according to a first embodiment of the present technology,

[0028] Fig. 3 shows a flushing arrangement according to a second embodiment of the present technology, and

[0029] Fig. 4 shows a vehicle with a fuel cell system according to an embodiment of the present technology.

[0030] Elements with the same function and mode of operation are provided with the same reference symbols in the figures.

[0031] Fig. 1 shows a fuel cell system 12 with a fuel cell stack 18, a simplified cathode subsystem 22, and a simplified anode subsystem 11. The fuel cell stack 18 has an anode 25 and a cathode 26. The cathode subsystem 22 has a cathode exhaust line 23 for conducting cathode exhaust gas from the cathode 26. The anode subsystem 11 has an anode exhaust line 13 for conducting anode exhaust gas 20 from the anode 25 and from the anode subsystem 11. The anode subsystem has an inlet valve 28 and an injector 27 for the controlled conduction of fuel to the anode 25. In a recirculation path 34, the anode subsystem 11 has a fuel recirculation conveyor in the form of a blower 29. Upstream of the blower 29 there is a water separator 30 through which anode exhaust gas 20 can be directed either into the recirculation path 34 or via an anode purge valve 31 into the anode exhaust gas line 13.

[0032] Downstream of the anode purge valve 31, the anode subsystem 11 has a purge assembly 10, via which the anode exhaust gas 20 is combined with the cathode exhaust gas 19 in the cathode exhaust gas line 23. In the section where the anode exhaust gas line 13 is combined with the cathode exhaust gas line 23, a collecting exhaust gas line 21 begins, through which the gas mixture of anode exhaust gas 20 and cathode exhaust gas 19 can be conducted into the environment of the fuel cell system 12, as shown in detail in Figures 2 and 3.

[0033] A buffer means 14 for buffering the anode exhaust gas flow is positioned in the purge assembly 10 or the anode exhaust gas line 13. The buffer means 14 comprises porous material in the form of a woven and / or fiber material for buffering the anode exhaust gas flow. The purge assembly 10 further comprises a bypass 15 with a bypass valve for selectively directing the anode exhaust gas 20 past the buffer means 14 into the cathode exhaust gas line 23 or toward the collecting exhaust gas line 21. The buffer means 14 and the bypass 15 are configured in the same housing 16, which is located directly or approximately directly on the cathode exhaust gas line 23. Directly downstream of the buffer means 14 and upstream of the collecting exhaust line 21 and / or the cathode exhaust line 23 there is a mixing region 17 for mixing buffered anode exhaust gas 20 with cathode exhaust gas 19.

[0034] The illustrated fuel cell system 12 further includes a fuel sensor 24 downstream of the mixing region 17 in the collective exhaust line 21, as well as another fuel sensor 24 upstream of the mixing region 17 and downstream of the anode purge valve 31 in the anode exhaust line 13. In alternative embodiments, fewer, more, or no fuel sensors 24 are required for the purpose described above. Furthermore, it is possible for fuel sensors 24 to be provided at other and / or additional positions in the fuel cell system 12 and used accordingly. The illustrated fuel sensors 24 are configured to determine a fuel concentration in the anode exhaust line 13 and in the collective exhaust line 21, or are used to determine the respective fuel concentrations.The fuel sensors 24 are signal-connected to a controller 33, allowing the controller to control the bypass 15, and in particular the bypass valve of the bypass 15, depending on the determined fuel concentrations. By controlling the bypass valve, an anode exhaust gas flow through the bypass line of the bypass 15 can be controlled and / or regulated.

[0035] Fig. 2 shows a purging arrangement 10 according to a first embodiment in further detail. Fig. 2 shows, in particular, the cathode exhaust gas 19 or the corresponding cathode exhaust gas stream, the anode exhaust gas 20 or the corresponding anode exhaust gas stream, and the collected exhaust gas 32 or the corresponding collected exhaust gas stream. Furthermore, the porous buffer medium 14, the mixing region 17, and the bypass 15 are shown in further detail. Thus, with a view to Fig. 2, it can be seen in particular how and where the cathode exhaust gas 19 can purge buffered anode exhaust gas 20 from the buffer medium 14, so that the two exhaust gases can subsequently be mixed in the mixing region 17 to form the collected exhaust gas 32. In Fig. 2, the buffer means 14 is located rearward of the cathode exhaust line 23, so that the mixing region 17 is formed downstream of the buffer means 14 and at least partially upstream of the cathode exhaust line 23. In Fig.Figure 3 shows a second embodiment of the purging arrangement 10, according to which the buffer means 14 is positioned directly on the cathode exhaust line 23. In this case, the mixing region 17 is located substantially entirely within the cathode exhaust line 23 or in a line volume defined by the cathode exhaust line 23.

[0036] Fig. 4 shows a vehicle 100 as a road vehicle with a fuel cell system 12 as described above and two electric motors 40 for driving the vehicle 100. The electric motors 40 are positioned in the area of ​​the front axle and in the area of ​​the rear axle of the vehicle 100 as drive motors of the vehicle 100. The fuel cell system 12 is configured to supply power to the two electric motors 40 and is electrically connected to the electric motors 40 accordingly. The vehicle 100 further has a fuel tank 50 for supplying fuel to the fuel cell system 12.

[0037] The invention permits further design principles in addition to the embodiments illustrated. This means that the invention should not be considered limited to the embodiments explained with reference to the figures. List of reference symbols

[0038] Purging arrangement Anode subsystem Fuel cell system Anode exhaust line Buffer agent

[0039] Bypass housing mixing area fuel cell stack cathode exhaust anode exhaust

[0040] Collective exhaust line Cathode subsystem Cathode exhaust line Fuel sensor Anode

[0041] Cathode Injector Inlet valve Blower Water separator Anode purge valve Collective exhaust gas Controller

[0042] Recirculation path Electric motor Fuel tank Vehicle

Claims

Patent claims 1. Purging arrangement (10) for an anode subsystem (11) of a fuel cell system (12), comprising an anode exhaust gas line (13) for conducting anode exhaust gas (20) from the anode subsystem (11) into a collective exhaust gas line (21) of the fuel cell system (12), a buffer means (14) positioned in the anode exhaust gas line (13) for buffering an anode exhaust gas flow in the anode exhaust gas line (13), and a bypass (15) in the anode exhaust gas line (13) for conducting the anode exhaust gas (20) past the buffer means (14).

2. Purging arrangement (10) according to claim 1, characterized in that the buffer means (14) comprises porous material for buffering the anode exhaust gas stream.

3. Purging arrangement (10) according to one of the preceding claims, characterized in that the buffer means (14) comprises a fabric and / or fiber material for buffering the anode exhaust gas flow.

4. Flushing arrangement (10) according to one of the preceding claims, characterized by a housing (16), wherein the buffer means (14) and the bypass (15) are positioned in the housing (16).

5. Purging arrangement (10) according to one of the preceding claims, characterized by a mixing region (17) which is designed downstream of the buffer means (14) and upstream of the collecting exhaust gas line (21) for mixing buffered anode exhaust gas (20) with cathode exhaust gas (19).

6. A fuel cell system (12) comprising a fuel cell stack (18), a cathode subsystem (22) with a cathode exhaust line (23) and an anode subsystem (11) with an anode exhaust line (13) and a purge arrangement (10) according to one of the preceding claims.

7. Fuel cell system (12) according to claim 6, characterized in that the mixing region (17) for mixing the buffered anode exhaust gas (20) with the cathode exhaust gas (19) is positioned directly on the cathode exhaust gas line (23) and / or the collecting exhaust gas line (21).

8. Fuel cell system (12) according to one of claims 6 to 7, characterized by a fuel sensor (24) downstream of the mixing region (17) in the collective exhaust line (21) for determining a fuel concentration in the collective exhaust line (21) and a controller (33) for controlling the bypass (15) depending on the determined fuel concentration in the collective exhaust line (21).

9. Fuel cell system (12) according to one of claims 6 to 8, characterized by a fuel sensor (24) upstream of the mixing region (17) in the anode exhaust line (13) for determining a fuel concentration in the anode exhaust line (13) and a controller (33) for controlling the bypass (15) depending on the determined fuel concentration in the anode exhaust line (13).

10. A vehicle (100) comprising a fuel cell system (12) according to any one of claims 6 to 9 and at least one electric motor (40) for driving the vehicle (100), wherein the fuel cell system (12) is configured to supply power to the at least one electric motor (40).

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