Method for testing the tightness of a sealing device of a flow chamber component for an electrochemical cell system

Abstract

Method for testing the tightness of a sealing device (54) of a flow chamber component (40) for an electrochemical cell system (11) comprising the steps of: providing a test fluid in a flow chamber (41) of the flow chamber component (40) for the electrochemical cell system (11), wherein the flow chamber component (40) for the electrochemical cell system (11) comprises the sealing device (54) for sealing the flow chamber (41) for the process fluid by having a first component (43) directly or indirectly rest on a second component (44) at a contact area (47), such that the sealing device (54) is formed between the first component (43) and the second component (44) due to the direct or indirect contact between the first component (43) and the second component (44) at the contact area (47); arranging a detection device (50) for the test fluid in a space outside the flow chamber (41).Detect the test fluid flowing from the flow chamber (41) through the sealing device (54) as leakage fluid with the detection device (50), wherein the leakage fluid is directed into a collection chamber (57) bounded by the flow chamber component (40) itself after flowing through the sealing device (54) and the leakage fluid directed into the collection chamber (57) is detected with the detection device (50).

Description

[0001] The present invention relates to a method for testing the tightness of a sealing device of a flow chamber component for an electrochemical cell system according to the preamble of claim 1, a flow chamber component for an electrochemical cell system according to the preamble of claim 10 and an electrochemical cell system according to the preamble of claim 15. State of the art

[0002] Fuel cell units, as galvanic cells, convert continuously supplied fuel and oxidant into electrical energy and water via redox reactions at an anode and cathode. Fuel cells are used in a wide variety of stationary and mobile applications, for example, in homes without a connection to the power grid, in motor vehicles, rail transport, aviation, space travel, and shipping. In fuel cell units, a large number of fuel cells are arranged in a stack.

[0003] In fuel cell units, a large number of fuel cells are arranged in a fuel cell stack. Within each fuel cell, there is a gas chamber for the oxidizer, that is, a flow chamber for the passage of an oxidizer, such as ambient air containing oxygen. The gas chamber for the oxidizer is formed by channels on the bipolar plate and by a gas diffusion layer for the cathode. The channels are thus formed by a corresponding channel structure on the bipolar plate, and the oxidizer, namely oxygen, reaches the cathode of the fuel cells through the gas diffusion layer. A gas chamber for the fuel is formed analogously at the anode.

[0004] Electrolysis cell units, consisting of stacked electrolysis cells, similar to fuel cell units, are used, for example, for the electrolytic production of hydrogen and oxygen from water. Furthermore, fuel cell units are known that can be operated as reversible fuel cell units and thus as electrolysis cell units. In addition, there are electrolysis cell units that are used exclusively for electrolysis. Fuel cell units and electrolysis cell units together form electrochemical cell units. Fuel cells and electrolysis cells together form electrochemical cells. In the fuel cell stack, channels for fuel, oxidant, and a coolant (process fluid) are provided. In the electrolysis cell stack, channels for electrolyte (process fluid) are provided.Electrochemical cell systems with a fuel cell unit or an electrolysis cell unit and at least one supply system for a process fluid include flow chamber components for the passage of process fluids.

[0005] The flow chamber components comprise a flow chamber for conveying or holding a process fluid, and this flow chamber is sealed by a sealing device. Examples of flow chamber components include process fluid lines or channels, valves, or a water separator. During manufacturing, operation, maintenance, or repair of the electrochemical cell system, the tightness of the sealing device of the flow chamber component must be tested. For flow chamber components used to convey hydrogen in fuel cell systems, the leakage volume flow rate should typically be less than 10 standard cm³. 3 / h. For this purpose, the entire sealing device must be arranged in a test chamber in a complex manner so that any leakage gas passing through the sealing device is completely collected in the test chamber and can then be detected by a detection device. However, this is complex because a correspondingly large test chamber is required for the flow chamber component. Furthermore, the flow chamber component must be disassembled from the electrochemical cell system in order to even be able to arrange it in the test chamber. It is also known to attempt to detect the leakage gas in the vicinity of the flow chamber component using a detection device. However, this is inaccurate because the leakage gas escapes into the surrounding air at the flow chamber component, and thus a leak with a small leakage volume flow cannot be detected, which is detrimental.

[0006] DE 10 2022 116 897 A1 discloses a method for detecting an internal leak in a fuel cell stack, comprising the following steps: providing a fully assembled fuel cell stack, each cell consisting of three chambers arranged one above the other, wherein a first chamber of each cell is filled with a gas at a first pressure, a chamber adjacent to the first chamber of each cell is filled with a gas at a second pressure higher than the first pressure, a test gas is continuously added to a higher-pressure gas from a nozzle moved perpendicular to the plane of the cells, while the nozzle is moved along the cells at a uniform speed, the gas exiting the first chambers is fed to a mass spectrometer, and the concentration of the test gas in the gas exiting the first chambers is measured with the mass spectrometer.and an internal leakage is detected between those adjacent chambers where the concentration of the test gas in the gas exiting the first chambers is highest during the full measurement.

[0007] DE 11 2009 005 091 B4 discloses a fuel system comprising a plurality of fuel storage units, a filling line system connecting the fuel storage units in parallel to a filling opening, and a supply line system connecting the fuel storage units in parallel for the purpose of fuel supply, wherein the fuel system further comprises: an integrated branch formed by combining a filling pipe branch arranged at the branch point of lines of the filling line system and a supply pipe branch arranged at the branch point of lines of the supply line system, wherein the integrated branch has a leakage test opening designed to allow the introduction of a flow medium for leakage testing into the filling line system and the supply line system.

[0008] WO 2021 / 237259 A1 discloses a method for releasing a fluid device, in particular a fuel cell system, at the end of a production line for the fluid device, comprising the following steps: introducing a test fluid into the fluid device to build up internal pressure in the fluid device, moving a detector device along at least one sealing section of the fluid device, detecting test fluid escaping from the fluid device, and introducing an additional fastening force into a fastening element of the fluid device in the area of ​​the detected, escaped test fluid. Disclosure of the invention Advantages of the invention

[0009] Inventive method for testing the tightness of a sealing device of a flow chamber component for an electrochemical cell system comprising the steps of: Maintaining a test fluid in a flow chamber of the flow chamber component for the electrochemical cell system, wherein the flow chamber component for the electrochemical cell system comprises the sealing device for sealing the flow chamber for the process fluid by having a first component rest directly or indirectly on a second component at a contact area, such that the sealing device is formed between the first component and the second component due to the direct or indirect contact between the first component and the second component at the contact area; arranging a detection device for the test fluid in a space outside the flow chamber.Detecting the test fluid flowing from the flow chamber containing the test fluid through the sealing device as leakage fluid with the detection device, wherein the leakage fluid is directed into a collection chamber bounded by the flow chamber component itself after flowing through the sealing device, and the leakage fluid directed into the collection chamber is detected with the detection device.

[0010] In another embodiment, the detection device, preferably a sensor of the detection device, is arranged, in particular completely, outside the collection space.

[0011] In a supplementary variant, the collection space is formed in the direction of flow of the test fluid through the contact area after the contact area.

[0012] In an additional embodiment, the detection of the test fluid flowing through the sealing device as leakage fluid is carried out by introducing an additional fluid, in particular ambient air, into the collection chamber, mixing the additional fluid with the leakage fluid in the collection chamber, draining the mixture of leakage fluid and additional fluid from the collection chamber, and detecting the leakage fluid with the detection device in the mixture of leakage fluid and additional fluid outside the collection chamber.

[0013] In a further embodiment, the contact area has a first end facing the flow chamber and a second end facing the collection chamber, and the second end of the contact area opens substantially completely into the collection chamber, in particular the collection chamber is formed substantially completely around the contact area, and the leakage fluid flows through the sealing device by the test fluid flowing into the contact area at the first end, then flowing through the contact area and flowing from the contact area into the collection chamber at the second end. The second end of the contact area opens substantially completely into the collection chamber, i.e., at least 90%, 95%, or 98% of the second end of the contact area opens into the collection chamber and / or is arranged in and / or on the collection chamber.

[0014] Preferably, the additional fluid is introduced into the collection space by introducing the additional fluid into the collection space through a first opening leading into the collection space, and by draining the mixture of leakage fluid and additional fluid out of the collection space through a second opening leading into the collection space.

[0015] In another variant, a negative pressure is created at the second opening compared to the pressure in the collection chamber, so that the additional fluid flows into the collection chamber through the first opening due to the negative pressure in the collection chamber, and the mixture of leakage fluid and additional fluid flows out of the second opening.

[0016] In an additional embodiment, a suction device is arranged at the second opening, and the mixture of leakage fluid and additive fluid is drawn from the second opening with the suction device and directed to the detection device, in particular to a sensor of the detection device, so that the leakage fluid in a mixture of leakage fluid and additive fluid is detected by the detection device, in particular a sensor of the detection device.

[0017] In a supplementary configuration, the test fluid, the leakage fluid, and the additive fluid are all gases. Therefore, the mixture of leakage fluid and additive fluid in the collection chamber is also a gas.

[0018] A flow chamber component according to the invention, in particular a process fluid line and / or a valve and / or a water separator and / or an injector, for an electrochemical cell system for converting electrochemical energy into electrical energy as a fuel cell system and / or for converting electrical energy into electrochemical energy as an electrolysis cell system, and in the flow chamber component a flow chamber for conveying a process fluid for the electrochemical cell system is formed, and the flow chamber component comprises a sealing device for sealing the flow chamber for the process fluid by having a first component of the flow chamber component rest directly or indirectly on a second component of the flow chamber component at a contact area.such that, due to the indirect or direct contact between the first and second components, a sealing device is formed at the contact area, wherein a collection space bounded by the flow space component itself is formed at the contact area, so that a leakage fluid flowing through the contact area flows from the flow space into the collection space.

[0019] In a further embodiment, the contact area has a first end facing the flow chamber and a second end facing the collection chamber, and the second end of the contact area opens substantially completely into the collection chamber, in particular the collection chamber is formed substantially completely around the second end. The second end of the contact area opens substantially completely into the collection chamber, i.e., at least 90%, 95%, or 98% of the second end of the contact area opens into the collection chamber and / or is arranged in and / or on the collection chamber.

[0020] In particular, the flow chamber component has a first opening for introducing an additional fluid into the collection chamber and a second opening for venting a mixture of leakage fluid and additional fluid from the collection chamber.

[0021] In another variant, the first opening and / or second opening is temporarily sealed fluid-tight with a removable sealing element.

[0022] In an additional embodiment, the first component rests indirectly on a second component at the contact area by arranging a seal, preferably elastic, in particular as an O-ring seal, between the first component and the second component.

[0023] An electrochemical cell system according to the invention for converting electrochemical energy into electrical energy as a fuel cell system and / or for converting electrical energy into electrochemical energy as an electrolysis cell system, comprising an electrochemical cell unit as a fuel cell unit and / or an electrolysis cell unit, at least one supply system for at least one process fluid, wherein the electrochemical cell unit and / or the at least one supply system comprises at least one flow space component in which a flow space for conveying a process fluid for the electrochemical cell system is formed.Each flow chamber component comprises a sealing device for sealing the flow chamber for the process fluid, wherein a first component of the flow chamber component rests directly or indirectly on a second component of the flow chamber component at a contact area, such that the sealing device is formed between the first and second components due to the direct or indirect contact between the first and second components at the contact area, wherein at least one flow chamber component is configured such that a method described in this patent application can be carried out with a detection device for a test fluid and / or the electrochemical cell system comprises at least one flow chamber component described in this patent application.

[0024] In another embodiment, the first component rests on a second component at the contact area, either directly or indirectly, with a compressive force and / or pressure.

[0025] In a further embodiment, the volume of the collection chamber is smaller than the volume of the flow chamber, in particular smaller than 90%, 70%, 50%, or 30% of the volume of the flow chamber. The collection chamber integrated into the flow chamber component thus requires little installation space, so that the flow chamber component is advantageously compact.

[0026] In another variant, the collection chamber is sealed in a direction away from the sealing device with at least one sealing part.

[0027] It is advisable that at least one sealing element be subjected to a pressure force between the first component and the second component.

[0028] In a further embodiment, the sealing part is a seal, preferably elastic, in particular an O-ring seal.

[0029] Preferably, the sealing element is arranged between the first and second components.

[0030] In a supplementary embodiment, the distance in one direction is essentially constant, in particular with a deviation of less than 30°, 20° or 10°, parallel to the flow direction of the leakage fluid through the sealing device between the at least one sealing part and the sealing device, in particular with a deviation of less than 30%, 20% or 10%.

[0031] In another variant, the seal of the sealing device is designed as a single piece or in multiple parts.

[0032] Preferably, the seal and / or the collection chamber and / or the at least one sealing part are designed with an essentially identical geometry, for example circular, straight, linear or rectangular.

[0033] In a supplementary embodiment, the extent of the collection chamber in one direction essentially perpendicular to the flow direction of the leakage fluid through the sealing device, particularly with a deviation of less than 30°, 20°, or 10°, is greater than the extent of the collection chamber in one direction essentially parallel to the flow direction of the leakage fluid through the sealing device, particularly with a deviation of less than 30°, 20°, or 10°, and particularly greater than two, three, five, or ten times the extent of the collection chamber in one direction essentially parallel to the flow direction of the leakage fluid through the sealing device. Thus, the collection chamber advantageously requires little installation space in the flow direction of the leakage fluid through the sealing device.

[0034] The sealing element is expediently designed as a plug and / or a screw and / or a cover, in particular a cover with thread or bayonet connection, and / or a flap and / or a slide.

[0035] In a supplementary variant, the flow chamber component has several separate flow chambers for conveying a process fluid for the electrochemical cell system, and the flow chamber component comprises several sealing devices for sealing the flow chambers for the at least one process fluid by having at least one first component of the flow chamber component rest directly or indirectly on at least one second component of the flow chamber component at several contact areas, such that several sealing devices are formed between the at least one first component and the at least one second component at the several contact areas due to the direct or indirect contact between the at least one first component and the at least one second component, wherein a collection chamber, in particular only one, bounded by the flow chamber component itself, is formed at the contact areas.so that a leakage fluid flowing through the multiple contact areas flows from at least one flow chamber into the collection chamber. This allows the tightness of several sealing devices on one flow component to be tested simultaneously with one, and in particular only one, detection device.

[0036] In a further embodiment, the contact area has a first end facing the flow chamber and a second end facing the collection chamber, and the first end of the contact area opens substantially completely into the flow chamber, in particular, the contact area is formed substantially completely around the flow chamber. The first end of the contact area opens substantially completely into the flow chamber, i.e., at least 90%, 95%, or 98% of the first end of the contact area opens into the flow chamber and / or is arranged in and / or on the flow chamber.

[0037] Preferably, the collection space is limited by the first component and / or the second component.

[0038] In a further embodiment, a pre-tensioning device applies a compressive force to the first component and the second component, so that the first and second contact surfaces lie against each other directly or indirectly with a compressive force and / or pressure at the contact area, and preferably the first and second components rest on the at least one sealing part with a compressive force.

[0039] In a complementary variant, the test fluid is held in the flow space of the flow space component for the electrochemical cell system by guiding the test fluid through the flow space of the flow space component for the electrochemical cell system, particularly during the detection of the leakage fluid with a detection device. Guiding the test fluid through the flow space of the flow space component also necessitates holding the test fluid in the flow space of the flow space component.

[0040] In a further embodiment, particularly during the detection of the leakage fluid with the detection device, the test fluid is maintained in the flow chamber at a pressure greater than 1 bar, 2 bar, 3 bar, 5 bar, 10 bar, 20 bar or 50 bar and / or at a pressure that corresponds substantially, particularly with a deviation of less than 30%, 20% or 10%, to the maximum pressure of the process fluid in the flow chamber during the operation of the electrochemical cell system.

[0041] It is advantageous, particularly during the detection of the leakage fluid with a detection device, for the pressure of the mixture of leakage fluid and additive fluid in the collection chamber to be lower than the ambient air pressure, specifically lower than the ambient air pressure minus 0.1 bar or minus 0.3 bar. This prevents the mixture from escaping the collection chamber into the ambient air, allowing only ambient air to flow into the collection chamber. The leakage can thus be detected with exceptional accuracy.

[0042] Preferably, the components of the electrochemical cells are formed in layers and span fictitious planes.

[0043] In a further embodiment, the fuel cell system comprises a fuel supply system with a pressure vessel for fuel as a process fluid and an oxidant supply system with a gas conveying device for oxidant as a process fluid and / or at least one discharge opening for discharging at least one process fluid into the environment.

[0044] In a further embodiment, the electrolysis cell system comprises an electrolyte supply system with a storage container for electrolyte and a pump for electrolyte and preferably a separator for hydrogen and / or a separator for oxygen.

[0045] In a complementary variant, the fuel cell system comprises a fuel cell unit, a cooling system, an oxidant supply system, and a fuel supply system.

[0046] In a further embodiment, the electrochemical cells each comprise as components an ion exchange membrane, in particular a proton exchange membrane and / or anion exchange membrane, an anode, a cathode, preferably at least one gas diffusion layer, and / or at least one separator plate, in particular a bipolar plate. In contrast to fuel cells, electrolysis cells do not require bipolar plates, but rather bipolar plates as separator plates consisting of only one plate, because electrolysis cells do not have a channel for coolant. In fuel cells, at least one channel for coolant is formed between the two plates of the bipolar plate.

[0047] Preferably, the fuel is hydrogen, hydrogen-rich gas, reformate gas or natural gas.

[0048] The electrochemical cells and / or components of the electrochemical cells are expediently designed to be essentially flat and / or disc-shaped.

[0049] In another variant, the electrochemical cell unit comprises a housing and / or a connection plate. The stack is enclosed by the housing and / or the connection plate.

[0050] Preferably, the connection plate has at least one inlet opening and / or at least one outlet opening.

[0051] In a complementary variant, the oxidizing agent is air with oxygen or pure oxygen.

[0052] Preferably, the fuel cell unit is a PEM fuel cell unit with PEM fuel cells, or a SOFC fuel cell unit with SOFC fuel cells, or an alkaline fuel cell (AFC). Brief description of the drawings

[0053] Exemplary embodiments of the invention are described in more detail below with reference to the accompanying drawings. These show: Fig. 1 a highly simplified representation of a fuel cell system, Fig. 2 a highly simplified representation of an electrolysis cell system and Fig. 3 a cross-section of a flow space component of an electrochemical cell system with a detection device for a test fluid in a first embodiment, Fig. 4 a cross-section of a flow space component of an electrochemical cell system with a detection device for a test fluid in a second embodiment, Fig. 5 a cross-section of the flow space component of the electrochemical cell system in the second embodiment according to Fig. 4 without a detection device for a test fluid, Fig. 6 a longitudinal section of a flow space component of an electrochemical cell system without a detection device for a test fluid in a third embodiment and Fig. 7 a cross-section AA according to Fig. 6 of the flow space component in the third embodiment.

[0054] In Fig. Figure 1 shows a fuel cell unit 1 as a fuel cell stack 3, i.e., as a fuel cell stack 3. The fuel cell unit 1 comprises the fuel cell stack 3, a housing 13, and a connection plate 15. The housing 13 defines an interior space 14. The connection plate 15 also functions as a housing 13 and is fixed to the rest of the housing 13 by fixing elements 16, in particular screws 17. In the fuel cell stack 2, fuel cells 4 are stacked and arranged in a straight line as PEM fuel cells 5. Due to the large number of stacked fuel cells 4, approximately 300 to 400, these are arranged in Fig. 1. Not all components are shown for the sake of simplicity. The principle of fuel cells 4 is that electrical energy, or electric current, is generated by means of an electrochemical reaction. Hydrogen (H2) is fed to an anode (not shown) as a gaseous fuel in recirculation mode, and the anode forms the negative terminal. A gaseous oxidizing agent, namely air with oxygen, is fed to a cathode (not shown); that is, the oxygen in the air provides the necessary gaseous oxidizing agent. Reduction (electron uptake) takes place at the cathode. Oxidation (electron release) occurs at the anode. Fuel cells 4 also include an ion exchange membrane, specifically a proton exchange membrane (PEM), which is positioned between the anode and the cathode.On both sides of the PEM, facing the gas spaces, the electrodes are located as the anode and cathode (not shown). A unit consisting of the PEM and anode and cathode is called a membrane electrode assembly (MEA) (not shown). A gas diffusion layer (GDL) lies on top of the anode and cathode. A bipolar plate (not shown) rests on the GDL. The electrically conductive bipolar plate serves as a current collector, for water drainage, and for conducting the reaction gases.

[0055] In the fuel cell unit 1, the fuel cells 4 are arranged between two clamping elements 18, which act as clamping plates 19. An upper clamping plate 20 rests on the uppermost fuel cell 4, and a lower clamping plate 21 rests on the lowermost fuel cell 4. The clamping elements 18 exert a compressive force on the fuel cells 4; that is, the upper clamping plate 20 exerts a compressive force on the uppermost fuel cell 4, and the lower clamping plate 21 exerts a compressive force on the lowermost fuel cell 4. This clamps the fuel cell stack 3 to ensure a tight seal for the fuel, oxidizer, and coolant, particularly due to elastic seals, and also to minimize the electrical contact resistance within the fuel cell stack 3.To clamp the fuel cells 4 with the clamping elements 18, four connecting devices 22 are designed as bolts 23 on the fuel cell unit 1, which are subjected to tensile stress. The four bolts 23 are rigidly connected to the clamping plates 19.

[0056] The connection plate 15 and the lower clamping plate 21 each have an opening for introducing recirculating fuel into the recirculating fuel channels. They also each have an opening for discharging recirculating fuel from the recirculating fuel channels. The connection plate 15 and the lower clamping plate 21, as clamping elements 18, have further openings for introducing and discharging oxidizers, and openings (not shown) for introducing and discharging coolant. Thus, the connection plate 15 and the lower clamping plate 21 have a total of six openings (only partially shown). Fig. 1 shown).

[0057] A fuel cell system 2 comprises, in addition to the fuel cell unit 1, an oxidant supply system 26 for supplying the fuel cell stack 3 with air as the oxidant. The oxidant supply system 26 comprises a gas conveying device 27, for example a blower, a compressor, a turbo compressor, which is driven by an electric motor and / or a turbine, and oxidant lines 28.

[0058] The fuel cell system 2 comprises, in addition to the fuel cell unit 1, a fuel supply system 29 for supplying the fuel cell stack 3 with hydrogen as fuel. The fuel supply system 29 comprises a pressure vessel 30, a fuel line 31 as a process fluid line, valves (not shown) for fuel, in particular an injector for controlling the volume flow of fuel introduced from the fuel line 31 into the recirculation fuel line 32, a heat exchanger (not shown) for fuel, a pressure reducer (not shown), a recirculation fuel line 32 as a process fluid line, a recirculation fuel conveying device 33, an electric motor (not shown) for driving the recirculation fuel conveying device 33, and a water separator 34 for separating water from the recirculation fuel.A water tank (not shown) for collecting the water collected in the water separator 34, a drain valve (not shown) for draining water from the water tank, and a purge valve (not shown) for releasing recirculated fuel into the environment. In the fuel supply system 29 for supplying the fuel cell stack 3 with hydrogen as fuel, the hydrogen stored in the pressure vessel 30 at a high pressure of, for example, 400 bar is fed to the fuel cells 4 via the fuel line 31. After the fuel has passed through the fuel cells 4, the hydrogen is not completely consumed.The hydrogen extracted from the fuel cells 4 is then fed back to the fuel cells 4 in a closed loop via the recirculation fuel line 32. The recirculation fuel conveying device 33 is used to pump the recirculation fuel through the recirculation fuel line 32. After passing through the fuel cells 4, the moisture content of the fuel increases. To prevent excessive water or moisture content in the recirculation fuel, the fuel supply system 29 includes a water separator 34. The water separated in the water separator 34 is collected in the water tank (not shown) and discharged into the environment via the drain valve (not shown). Excess recirculation fuel is discharged into the environment via the purge valve (not shown).

[0059] Fuel cell system 2 comprises, in addition to fuel cell unit 1, a cooling system (not shown) for temperature control of the fuel cell stack 3. This cooling system includes coolant lines for process fluids, a heat exchanger, and a pump for circulating the coolant. The coolant is routed through coolant channels in the bipolar plates of the fuel cells 4, and the heat is dissipated to the environment via the heat exchanger. Fuel cell system 2 also includes, in addition to fuel cell unit 1, the oxidizer supply system 26, the fuel supply system 29, and the cooling system (not shown) as the coolant supply system.

[0060] The fuel cell unit 1 can optionally be used and operated as an electrolysis cell unit 6 with modifications not shown, particularly valves; that is, it forms a reversible fuel cell unit 1 or is designed to be operable only as an electrolysis cell unit 6. Some features that enable the operation of the fuel cell unit 1 as an electrolysis cell unit 6 are described below. A liquid electrolyte, namely highly diluted sulfuric acid with a concentration of approximately c(H₂SO₄) = 1 mol / L, is used for electrolysis. A sufficient concentration of hydronium ions (H₃O₄) is also required. + The liquid electrolyte is necessary for electrolysis. Fig. Figure 2 shows an electrolysis cell unit 6, which can only be used for electrolysis.

[0061] The polarity of the electrodes during electrolysis is reversed (not shown) when operating as electrolysis cell unit 6 compared to operation as fuel cell unit 1. This means that hydrogen (H₂) is formed at the cathodes in the fuel channels through which the liquid electrolyte is passed. The hydrogen (H₂) is then absorbed by the liquid electrolyte and transported along in solution. Similarly, the liquid electrolyte is passed through the oxidant channels, and oxygen (O₂) is formed at the anodes or in the oxidant channels. When operating as electrolysis cell unit 6, the fuel cells 2 of fuel cell unit 1 function as electrolysis cells 9. Fuel cells 2 and electrolysis cells 9 thus form electrochemical cells 24. The oxygen (O₂) produced is absorbed by the liquid electrolyte and transported along in solution.The hydrogen H2 produced is absorbed by the liquid electrolyte and transported in solution. The liquid electrolyte is stored in a storage container 35 and is pumped by a pump 37 and electrolyte lines 36 through the channels in the electrolysis cell stack 8. For a reversible fuel cell unit 1 (not shown) according to... Fig. 1. Two 3-way valves (not shown) are located on the recirculation fuel line 32 and the oxidizer line 28 and are switched during operation as the electrolysis cell unit 6, so that instead of recirculation fuel and oxidizer, the liquid electrolyte is introduced from the storage tank 35 into the recirculation fuel line 32 and the oxidizer line 28 as the electrolyte line 36 by the pump 37. A hydrogen separator 38 separates the hydrogen obtained from the electrolysis from the electrolyte. A separate oxygen separator 39 separates the oxygen obtained from the electrolysis from the electrolyte. The electrolyte is circulated through the electrolysis cell unit 6, and sulfuric acid is added according to consumption by a device (not shown).The electrolysis cell system 6 comprises, in addition to the electrolysis cell unit 6 with the electrolysis cell stack 8, an electrolyte supply system 12. The electrolyte supply system 12 includes the storage tank 35, the electrolyte lines 36, the pump 37, the hydrogen separator 38, and the oxygen separator 39. A fuel cell unit 1 and an electrolysis cell unit 6 form an electrochemical cell unit 25. A fuel cell system 2 and / or an electrolysis cell system 7 form an electrochemical cell system 11.

[0062] The fuel cell system 2 and / or the electrolysis cell system 7, as an electrochemical cell system 11, comprise flow chamber components 40 as single or multi-part components 40 for conveying a process fluid. The flow chamber component 40 is, for example, configured as a process fluid line 64. The process fluid line 64 is thus, for example, the oxidant line 28, the fuel line 31, the recirculation fuel line 32, and the electrolyte line 36. The flow chamber component 40 can also be formed, for example, by the water separator 34, the gas conveying device 27, the injector, a valve, the hydrogen separator 38, and the oxygen separator 39. The flow chamber component 40 is thus a general term for a device or means as a component for conveying and / or maintaining a process fluid.The flow chamber component 40 can also be formed by a module which, for example, structurally comprises several functional components integrated within the module, such as the hydrogen separator 34 together with a purge valve and the recirculation fuel conveying device 33 as functional components.

[0063] The module with the multiple functional components preferably has a common housing and / or holding device for integrating the functional components, wherein preferably at least one functional component is at least partially formed by the housing and / or the holding device itself.

[0064] In Fig. Figure 3 shows a first embodiment of the general and fundamental design of the flow chamber component 40. The flow chamber component 40 comprises a first component 43 and a second component 44. The first component 43 and the second component 44 define a flow chamber 41 for conveying and / or retaining a process fluid on an inner surface 42. The first component 43 indirectly rests on the second component 44 at a contact area 47. A first contact surface 45 of the first component 43 indirectly rests on a second contact surface 46 of the second component 44 at a contact area 47, with a seal 55, preferably elastic, in the form of an O-ring seal 56, resting on the first contact surface 45 and the seal 55, preferably elastic, in the form of an O-ring seal 56, resting on the second contact surface 46.The first contact surface 45 of the seal 55 on the first component 43 forms the contact area 47, and the second contact surface 46 of the seal 45 on the second component 44 also forms the contact area 47. An outer surface of the seal 55 facing the flow chamber 44 between the two contact areas 47 also forms the boundary surface 42 for limiting the flow chamber 41. An end of each contact area 47 facing the flow chamber 41 forms a first end 48 of the contact area 47, and an end of the contact area 47 facing away from the flow chamber 41 forms a second end 49 of the contact area 47. The seal 55, together with the first component 43 and the second component 44, forms a sealing device 54 at the contact area 47. The geometry of the seal 55 extends perpendicular to the plane of the drawing. Fig. 3 is arbitrary, for example in a section perpendicular to the drawing plane of Fig. 3. Circular, like the O-ring seal 56, or rectangular, straight, or linear, for example, wavy or meandering. The first contact surface 45 and the second contact surface 46 rest on the seal 55 with a compressive force or surface pressure, or pressure applied by means of a preloading device, for example, a union nut, bolt, or screw, by applying a corresponding compressive force to the first component 43 and the second component 44 (not shown). The elastic seal 55 is elastically deformed due to this compressive force.

[0065] A collection chamber 57 is formed between the first component 43 and the second component 44 and is bounded by the first component 43, the second component 44, and a portion of the outer surface of the seal 55, facing away from the flow chamber 41 and between the two contact areas 47. The geometry of the collection chamber 57 extends perpendicular to the plane of the drawing. Fig. 3 is analogous to seal 55, wherein in the Fig. In the embodiment shown in Figure 3, only one collection chamber 57 is present with respect to the sealing device 55. For example, the collection chamber 57 is thus shown in a section perpendicular to the plane of the drawing. Fig. 3. The collection chamber 57 is circularly formed when the seal 55 is configured as an O-ring seal 56. The collection chamber 57 is bounded by the first component 43, the second component 44, and the portion of the outer surface of the seal 55 facing the flow chamber 41, each forming a boundary surface 58 for the collection chamber 57. Additionally, the collection chamber 57 is sealed with air between the first component 43 and the second component 44 by a sealing element (not shown). This sealing element (not shown) is preferably designed as an elastic seal and has only two openings: a first opening 60 and a second opening 61. During normal operation of the flow chamber component 40, the first opening 60 and the second opening 61 are closed by a sealing element 62, specifically a sealing plug 63.This means that, during normal operation of the flow chamber component 40, the collection chamber 57 is sealed off from the environment. The geometry of the sealing element (not shown) extends perpendicular to the plane of the drawing. Fig. 3 is analogous to seal 55. The distance in the direction of the drawing plane of Fig. 3 between the sealing part not shown and the seal 55, in particular along the extension perpendicular to the plane of the drawing of Fig. 3, essentially constant, in particular with a deviation of less than 30%, 20% and 10%.

[0066] To test the tightness of the sealing device 54 of the flow chamber component 40, a test gas, namely helium or hydrogen, is passed through or maintained in the flow chamber 41 at a pressure significantly higher than the ambient air pressure, for example, at a pressure of 3 or 5 bar. Additionally, the two sealing elements 62 are removed from the first opening 60 and the second opening 61, and a line 52 of a detection device 50 is attached to the second opening 61. The detection device 50 comprises, in addition to a sensor 51 for detecting the test gas or leakage gas, a device for generating a vacuum, such as a blower 53. The sensor 51 is, for example, a mass spectrometer.In contrast, the sensor 51 can also be designed as a sensor 51 for detecting the leakage gas using a physical method, for example as an electrical resistance heating element and a temperature sensor for detecting the temperature of the electrical resistance heating element, so that the proportion of the leakage gas in the gas can be detected due to the temperature change of the electrical resistance heating element due to the density of a mixed gas of leakage gas and ambient air directed to the electrical resistance heating element.

[0067] The test fluid, namely helium or hydrogen, in the flow chamber 41 at an overpressure relative to the surroundings, flows from the flow chamber 41 into the contact area 47 at the first end 48 of the sealing device 54 and into the single collection chamber 57 at the second end 49 of the contact area 47. The length or extent of the first end 48 of the contact area 47 and the seal 55, particularly in a direction perpendicular to the plane of the drawing, Fig. 3. The analogously determined length or extent of the second end 49 of the contact area 47 and the analogously determined length or extent of the collection chamber 57 are essentially identical, in particular with a deviation of less than 30%, 20%, or 10%. All the leakage gas escaping through the sealing device 54 at the second ends 49 is thus completely introduced into the collection chamber 57. During the tightness test of the flow chamber component 40, a mixture of test gas and ambient air is drawn in and passed through the line 52 and the second opening 61 by the blower 53. This is because, due to the negative pressure in the collection chamber 57 relative to the surroundings, ambient air is introduced and drawn into the collection chamber 57 as an additional gas or fluid through the first opening 60.Even if there is a leak in the sealing part (not shown) between the first component 43 and the second component 44, this is harmless for testing the tightness of the flow chamber component 40, because it only introduces further additional gas into the collection chamber 57 in an analogous manner to the first opening 60, because there is a negative pressure in the collection chamber 57 relative to the surroundings.

[0068] In a further embodiment not shown, the flow chamber component 40 comprises several separate flow chambers 41, each sealed by several separate sealing devices 54. Analogous to the embodiment shown above, a collection chamber 57 is arranged and formed on the sealing devices 54. The collection chamber 57 for several sealing devices 54 has only one first opening 60 and only one second opening 61, so that the tightness of several sealing devices 54 of the flow chamber component 40 can be tested with a detection device 50. This flow chamber component 40 preferably comprises several functional components of the electrochemical cell system 11.

[0069] In Fig. 4 and Fig. Figure 5 shows a second embodiment of the flow chamber component 40 with the detection device 50. The following discussion focuses primarily on the differences compared to the first embodiment. Fig. 3 described. Fig. 4 The detection device 50 is arranged on the flow chamber component 40 during the testing of the sealing device 54. In Fig. In position 5, the flow chamber component 40 is in normal operation for the electrochemical cell system 11, such that the first opening 60 and the second opening 61 are each closed by the sealing element 62, i.e., the sealing plug 63. A contact area 47 exists between the first component 43 and the second component 44, forming a direct contact between the first component 43 and the second component 44, such that the first contact surface 45 of the first component 43 rests directly on the second contact surface 46 of the second component 44.

[0070] The sealing device 54 in this second embodiment is thus designed, for example, as a conical contact area 47 with two conically arranged first and second contact surfaces 45, 46. The first component 43 and the second component 44 are subjected to a compressive force at the first contact surface 45 and at the second contact surface 46, respectively, as the contact area 47, by means of a screw connection, for example, a union nut or screws, i.e., for example, as a compression fitting. A compressive force, in the form of surface pressure, is thus present between the first contact surface 45 and the second contact surface 46.

[0071] In Fig. 6 and Fig. Figure 7 shows a third embodiment of the flow chamber component 40 without the detection device 50. The following discussion focuses primarily on the differences compared to the second embodiment. Fig. 4 and Fig. 5 described. The first component 43 and the second component 44 are each a process fluid line 64. An axial end of the lines 64 rests against each other at the contact area 47, so that there is direct contact between the first contact surface 45 of the first component 43 and the second contact surface 46 of the second component 44. The first contact surface 45 and the second contact surface 46 are conical with respect to a longitudinal axis of the process fluid line 64. An annular wall profile 65 is arranged on the radial outer surface of the process fluid line 64. The wall profile 65 is shown in the section according to Fig. The contact area 6 is U-shaped and rests indirectly on the radial outer surface of the process fluid line 64 with a seal 66. The annular wall profile 65 is arranged completely around the radial outer surface of the process fluid line 64 in a circumferential direction 59. The second end 49 of the contact area 47 thus opens completely into the collection chamber 57. The collection chamber 57 is bounded by boundary surfaces 58 of the annular wall profile 65, the seal 66, and the radial outer surface of the process fluid line 64. Fig. 7 is a section AA perpendicular to the drawing plane of Fig.Figure 6 shows the first opening 60 and the second opening 61 on the annular-shaped wall profile 65, each of which is closed by the sealing element 62, i.e., the sealing plug 63, during normal operation of the flow chamber component 40. For testing the tightness of the flow chamber component 40, the sealing plugs 63 are removed, analogous to the embodiment described above, and the detection device 50 is arranged at the second opening 61 while the test gas is held in the flow chamber 41 at an overpressure.

[0072] Overall, the inventive method for testing the tightness of the sealing device 54 of the flow chamber component 40, the inventive flow chamber component 40, and the inventive electrochemical cell system 11 offers significant advantages. The tightness test of the sealing device 54 of the flow chamber component 40 can be easily performed on the flow chamber component 40 itself. Due to the arrangement of the collection chamber 47, selective testing of one or more sealing devices 54 of the flow chamber component 40 is possible. In particular, when testing the flow chamber component 40 after prolonged operation of the electrochemical cell system 11, this tightness test can be easily performed without having to arrange a large flow chamber component 40 in a large test chamber. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2022 116 897 A1

[0006] DE 11 2009 005 091 B4

[0007] WO 2021 / 237259 A1

[0008]

Claims

[1] Method for testing the tightness of a sealing device (54) of a flow chamber component (40) for an electrochemical cell system (11) comprising the steps: - Providing a test fluid in a flow chamber (41) of the flow chamber component (40) for the electrochemical cell system (11), wherein - the flow chamber component (40) for the electrochemical cell system (11) the sealing device (54) comprises for sealing the flow chamber (41) for the process fluid by a first component (43) resting directly or indirectly on a second component (44) at a contact area (47), so that the sealing device (54) is formed between the first component (43) and the second component (44) due to the direct or indirect contact between the first component (43) and the second component (44) at the contact area (47), - Arranging a detection device (50) for the test fluid in a space outside the flow space (41), - Detecting the test fluid flowing from the flow chamber (41) through the sealing device (54) as leakage fluid with the detection device (50), characterized by , that the leakage fluid is directed into a collection chamber (57) bounded by the flow chamber component (40) after flowing through the sealing device (54) and that the leakage fluid directed into the collection chamber (57) is detected by the detection device (50). [2] Method according to claim 1, characterized by that the detection device (50), preferably a sensor (51) of the detection device (50), is arranged, in particular completely, outside the collection space (57). [3] Method according to claim 1 or 2, characterized by, that the collection space (57) is formed in the direction of flow of the test fluid through the contact area (47) after the contact area (47). [4] Method according to one or more of the preceding claims, characterized by , that the detection of the test fluid flowing through the sealing device (54) as leakage fluid is carried out with the detection device (50) by introducing an additional fluid, in particular ambient air, into the collection chamber (57), mixing the additional fluid with the leakage fluid in the collection chamber (57), discharging the mixture of leakage fluid and additional fluid from the collection chamber (57) and detecting the leakage fluid with the detection device (50) in the mixture of leakage fluid and additional fluid outside the collection chamber (57). [5] Method according to claim 4, characterized by, that the contact area (47) has a first end (48) facing the flow space (41) and a second end (49) facing the collection space (57) and the second end (49) of the contact area (47) opens substantially completely into the collection space (57), in particular the collection space (57) is formed substantially completely around the contact area (47), and the leakage fluid flows through the sealing device (54) by the test fluid flowing into the contact area (47) at the first end (48), then flowing through the contact area (47) and flowing from the contact area (47) into the collection space (57) at the second end (49). [6] Method according to claim 4 or 5, characterized by, that the additional fluid is introduced into the collection space (57) by introducing the additional fluid into the collection space (57) through a first opening (60) opening into the collection space (57) and by diverting the mixture of leakage fluid and additional fluid out of the collection space (57) through a second opening (61) opening into the collection space. [7] Method according to claim 6, characterized by , that a negative pressure is created at the second opening (61) compared to the pressure in the collection chamber (57), so that the additional fluid flows into the collection chamber (57) through the first opening (60) due to the negative pressure in the collection chamber (57) and the mixture of leakage fluid and additional fluid flows out of the second opening (61). [8] Method according to one or more of the preceding claims, characterized by, that a suction device (53) is arranged at the second opening (61) and that the mixture of leakage fluid and additive fluid is drawn from the second opening (61) by the suction device (53) and directed to the detection device (50), in particular to a sensor (51) of the detection device (50), so that the leakage fluid in a mixture of leakage fluid and additive fluid is detected by the detection device (50), in particular by a sensor (51) of the detection device (50). [9] Method according to one or more of the preceding claims, characterized by that the test fluid, the leakage fluid and the additional fluid are a gas. [10] Flow chamber component (40), in particular a process fluid line (64), a valve, a water separator (34) and / or an injector, for an electrochemical cell system (11) for converting electrochemical energy into electrical energy as a fuel cell system (2) and / or for converting electrical energy into electrochemical energy as an electrolysis cell system (7) and - in the flow space component (40) a flow space (41) is formed for conveying a process fluid for the electrochemical cell system (11) and - the flow chamber component (40) comprises a sealing device (54) for sealing the flow chamber (41) for the process fluid by having a first component (43) of the flow chamber component (40) rest directly or indirectly on a second component (44) of the flow chamber component (40) at a contact area (47), such that the sealing device (54) is formed between the first component (43) and the second component (44) due to the direct or indirect contact between the first component (43) and the second component (44) at the contact area (47), characterized by , that a collection space (57) is formed at the contact area (47) which is itself bounded by the flow space component (40), so that a leakage fluid flowing through the contact area (47) flows from the flow space (40) into the collection space (57). [11] Flow space component according to claim 10, characterized by, that the contact area (47) has a first end (48) facing the flow space (41) and a second end (49) facing the collection space (57) and that the second end (49) of the contact area (47) essentially completely opens into the collection space (57), in particular that the collection space (57) is formed essentially completely around the second end (49). [12] Flow chamber component according to claim 10 or 11, characterized by , that a first opening (60) for introducing an additional fluid into the collection chamber (57) and a second opening (61) for discharging a mixture of leakage fluid and additional fluid from the collection chamber (57) is formed on the flow chamber component (40). [13] Flow space component according to claim 12. characterized by , that the first opening (60) and / or second opening (61) is temporarily sealed fluid-tight with a removable sealing element (62). [14] Flow space component according to one or more of claims 10 to 13, characterized by , that the first component (43) indirectly rests on a second component (44) at the contact area (47) by arranging a seal (55), preferably elastic, in particular as an O-ring seal (56), between the first component (43) and the second component (44). [15] Electrochemical cell system (11) for converting electrochemical energy into electrical energy as a fuel cell system (2) and / or for converting electrical energy into electrochemical energy as an electrolysis cell system (7), comprising - an electrochemical cell unit (25) as a fuel cell unit (1) and / or an electrolysis cell unit (6), - at least one supply system (12, 26, 29) for at least one process fluid, wherein - the electrochemical cell unit (25) and / or the at least one supply system (12, 26, 29) comprises at least one flow space component (40), - in which a flow space (41) is formed in each flow space component (40) for conveying a process fluid for the electrochemical cell system (11), - each flow chamber component (40) comprises a sealing device (54) for sealing the flow chamber (41) for the process fluid by having a first component (43) of the flow chamber component (40) rest directly or indirectly on a second component (44) of the flow chamber component (40) at a contact area (47), such that the sealing device (54) is formed between the first component (43) and the second component (44) due to the direct or indirect contact between the first component (43) and the second component (44) at the contact area (47), characterized by , that at least one flow space component (40) is designed such that a method according to one or more of claims 1 to 9 can be carried out with a detection device (50) for a test fluid. and / or the electrochemical cell system (11) comprises at least one flow space component (40) according to one or more of claims 10 to 14.

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