Water separator for a fuel cell system, fuel cell system, ultrasonic measuring system and measuring method

Abstract

The present invention relates to a water separator (10) for a fuel cell system (100), the water separator (10) having: an inlet opening (16) for an anode discharge section (122) of the fuel cell system (100), for admitting anode exhaust gas (3) from the fuel cell system (100); a storage volume (4) for storing water (1) separated from the anode exhaust gas (3); and an outlet opening (14) for discharging the water (1) stored in the storage volume (4), the water separator (10) having an ultrasonic measuring system (20) comprising at least one ultrasonic sensor (22, 24) for measuring a water level (2) of the water (1) and for measuring a hydrogen concentration in the anode exhaust gas (3).

Description

[0001] Water separator for a fuel cell system, fuel cell system, ultrasonic measuring system and measuring method

[0002] The present invention relates to a water separator for a fuel cell system, wherein the water separator has an inlet opening for an anode discharge section of the fuel cell system for admitting anode exhaust gas from the fuel cell system, a storage volume for storing water separated from the anode exhaust gas, and an outlet opening for discharging the water stored in the storage volume. Furthermore, the invention also relates to a fuel cell system with such a water separator, an ultrasonic measuring system for a water separator, and a measuring method for the water separator, the fuel cell system, or the ultrasonic measuring system.

[0003] Especially in PEM fuel cell systems, it is very important to ensure a sufficient supply of hydrogen to the anode. An undersupply of hydrogen can lead to severe degradation effects and significantly shorten the service life of the fuel cell stack. On the other hand, hydrogen waste must be avoided. Therefore, measuring the hydrogen concentration can enable optimization in terms of efficiency and service life.

[0004] Measuring hydrogen concentration in fuel cell systems, especially those for automotive applications, can be a significant challenge due to the limited space available for integrating additional sensors. Existing solutions require a significant amount of space for integrating such sensors. However, smaller (automotive) sensors on the market are not very robust due to the moist and acidic environment in the anode of the fuel cell system.

[0005] Currently, cost-intensive mass spectrometers are used to measure hydrogen concentrations. These typically permanently remove gas from the anode volume in the fuel cell stack, which should be avoided.

[0006] The object of the present invention is to at least partially remedy the disadvantages described above. In particular, the object of the present invention is to provide a space-optimized and precise measurement of the operating parameters of a fuel cell system in a cost-effective and simple manner.

[0007] The above object is achieved by a water separator having the features of claim 1, a fuel cell system having the features of claim 11, an ultrasonic measuring system according to claim 12, and a measuring method having the features of claim 13. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the water separator according to the invention naturally also apply in connection with the fuel cell system according to the invention, the ultrasonic measuring system according to the invention, the measuring method according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made to each other.

[0008] According to the invention, a water separator for a fuel cell system is provided, wherein the water separator has an inlet opening for an anode discharge section of the fuel cell system for admitting anode exhaust gas from the fuel cell system, a storage volume for storing water separated from the anode exhaust gas, and an outlet opening for discharging the water stored in the storage volume. The water separator further has an ultrasonic measuring system with at least one ultrasonic sensor for measuring a water level of the water, in particular in the storage volume, and for measuring a hydrogen concentration of the anode exhaust gas, in particular in the storage volume.

[0009] According to the invention, an ultrasonic measuring system is used which, with one or more sensors in a water separator, can measure both the water level of the water separator and the hydrogen concentration in the water separator. Unlike in the prior art, therefore, no different measuring systems and sensors are necessary. The inventive provision of a single measuring system for both measurements therefore not only allows for compact use of installation space within and / or on the water separator and thus in the fuel cell system, but is also cost-effective and allows for particularly precise measurement using the same ultrasonic measuring principle. This measuring principle is robust against the operating conditions in the anode loop with the liquid water droplets. It can also be constructed very compactly to further minimize the installation space requirement.Providing two measurement options also improves calibration and thus the optimization of the fuel cell system.

[0010] It can be advantageous if a first ultrasonic sensor is configured to measure the water level and a second ultrasonic sensor is configured to measure the hydrogen concentration in the anode exhaust gas. This means that the ultrasonic measuring system has at least two ultrasonic sensors, each of which can perform different types of measurements, which will later also be referred to as level measurement and concentration measurement. The configuration of the sensors for these different measuring tasks can be realized, for example, through their design, their relative positioning or the positioning of their measuring direction and / or additional possible elements, such as measuring element surfaces. This advantageously allows simultaneous measurement of both the water level and the hydrogen concentration, so that these can also be continuously monitored.

[0011] It can also be advantageous if the two ultrasonic sensors are arranged on the same wall section of the water separator. The wall section can, for example, be a side wall, particularly the inner wall, of the water separator. This enables a comparatively compact design because the ultrasonic sensors do not have to be located far from each other and thus from other measuring system components, which would require additional installation space, for example, due to the corresponding cabling, and incur additional costs.

[0012] It can also be advantageous if the two ultrasonic sensors are arranged side by side. This means that the two ultrasonic sensors are in close proximity to each other. This also allows for the aforementioned compact design.

[0013] Furthermore, it can be advantageous if the ultrasonic measuring system has at least one measuring system component that is at least partially shared by the two ultrasonic sensors. Such at least one measuring system component can be, for example, a measurement control unit, cabling, a power supply, etc. Because the two ultrasonic sensors share at least one, several, or all of the measuring system components required for the measurements, redundancy in the measuring system components, which could lead to a potential component failure, can be avoided, in favor of a compact and cost-effective design of the ultrasonic measuring system and thus of the fuel cell system in which it is used.

[0014] It can also be advantageous if the at least one ultrasonic sensor and / or a measuring element surface of the ultrasonic measuring system is mounted so as to be movable between two measuring positions in order to measure the water level in a level measuring position of the two measuring positions and to measure the hydrogen concentration of the anode exhaust gas in a concentration measuring position of the two measuring positions. The movable mounting can be provided, for example, by a rotary mounting and / or translational mounting, which enables rotation or translational movement of the at least one ultrasonic sensor and / or the measuring element surface. For the movement, a drive can be provided on the measuring element surface and / or the at least one ultrasonic sensor, which is controlled accordingly by the ultrasonic measuring system in order to provide one of the two measuring positions.This allows a single ultrasonic sensor to perform both types of measurements, i.e., concentration measurement and level measurement. This can be beneficial if one of two possible ultrasonic sensors fails. However, the ultrasonic measuring system can also be equipped with just one ultrasonic sensor, which can perform both types of measurements depending on the selected measuring position. In this case, at least for precise measurements, only one measurement of the water level and concentration measurement will typically be possible at different times.

[0015] It can be advantageous if the at least one ultrasonic sensor has a measuring direction aligned with a water surface of the water stored in the storage volume for measuring the hydrogen concentration of the anode exhaust gas. Equipped with this measuring direction, the ultrasonic sensor can determine the distance between the at least one ultrasonic sensor and the water surface as the level of the storage volume. If the dimensions of the water separator are known, this distance can be assigned to a water fill level. For example, a formula, an assignment table, or the like can assign a water fill level to the distance measured by the ultrasonic sensor, which water level can be determined by the ultrasonic measuring system. The fill level measuring position can in particular be a measuring position in which the measuring direction of the ultrasonic sensor is aligned with the water surface.

[0016] It may also be advantageous if the at least one ultrasonic sensor has a measuring direction for measuring the hydrogen concentration that is aligned with a measuring element surface of the ultrasonic measuring system in the water separator. This allows the hydrogen concentration to be measured, in particular, in a different measuring direction than that for measuring the water level.

[0017] In principle, it can also be advantageous if the hydrogen concentration is measured in the same direction as the water level. For this purpose, a fixed geometry (i.e., the measuring element surface next to the water surface) can be advantageously present in the "line of sight" of the sound source, and the two different signals (level and concentration) can be separated through appropriate signal analysis and / or processing.

[0018] The measuring element surface can preferably be arranged on a measuring element within the water separator, in particular within the storage volume. Such a measuring element can, for example, protrude from an inner wall of the water separator toward the inside of the water separator, in particular into the storage volume, or can be formed as an inner wall of the water separator. The measuring element can be formed from a solid material, for example, plastic, metal, or the like, which preferably has sufficiently resistive properties for use in the water separator, i.e., can, for example, have a specific coating. The measuring element can also be made of the same material as the wall of the water separator, in particular, be formed integrally therewith.

[0019] The measuring element surface can advantageously have a predetermined distance from the at least one ultrasonic sensor. Because the distance is predetermined, it is always known and thus the ultrasound emitted by the ultrasonic sensor requires a different amount of time at different hydrogen concentrations until it is reflected by the measuring element surface and registered again by the ultrasonic sensor. Here too, for example, a formula, an assignment table or the like can be used to assign a hydrogen concentration for the respective time period from transmission to reception of the ultrasound, which can be determined by the ultrasonic measuring system. In the case of a movably mounted measuring element surface, the distance can optionally also be adjustable, although the distance is known from a measurement or predetermined bearing positions of the measuring element surface.

[0020] The present invention also relates to a fuel cell system, comprising at least one fuel cell stack with an anode section and a cathode section, an anode feed section for supplying anode feed gas to the anode section, a cathode feed section for supplying cathode feed gas to the cathode section, an anode discharge section for discharging anode exhaust gas, and a cathode discharge section for discharging cathode exhaust gas, wherein a water separator according to the invention is arranged in the anode discharge section.

[0021] Thus, a fuel cell system according to the invention offers the same advantages as those explained in detail with reference to the water separator according to the invention. The fuel cell system can be of any type, for example, a polymer electrolyte membrane (PEM) type.

[0022] The present invention also relates to an ultrasonic measuring system for a water separator, in particular the water separator according to the invention, for a fuel cell system, in particular the fuel cell system according to the invention, wherein the ultrasonic measuring system has at least one ultrasonic sensor for measuring a water level of water in the water separator and for measuring a hydrogen concentration of an anode exhaust gas in the water separator.

[0023] Thus, an ultrasonic measuring system according to the invention brings with it the same advantages as have been explained in detail with reference to the water separator according to the invention.

[0024] Furthermore, the present invention also relates to a measuring method for the water separator according to the invention, for the fuel cell system according to the invention or for the ultrasonic measuring system according to the invention, wherein the measuring method comprises the following steps, which are each carried out by means of the ultrasonic measuring system:

[0025] - Level measurement of the water level of the water and

[0026] - Measuring the hydrogen concentration of the anode exhaust gas.

[0027] Thus, a measuring method according to the invention also brings with it the same advantages as have been explained in detail with reference to the water separator according to the invention.

[0028] It can be advantageous if the level measurement and the concentration measurement are carried out simultaneously, at least for some time. This has the advantage that the water level and the hydrogen concentration can be monitored at least temporarily in parallel, especially continuously, using two ultrasonic sensors of the ultrasonic measuring system.

[0029] However, it can also be advantageous to perform level measurement and concentration measurement at different times. This has the advantage that a single ultrasonic sensor can be used for both level measurement and concentration measurement.

[0030] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments are described in detail with reference to the drawings. They show schematically:

[0031] Fig. 1 is a schematic view of an exemplary embodiment of a fuel cell system according to the invention,

[0032] Fig. 2 is a schematic detailed view of a water separator according to the invention according to an exemplary embodiment of the invention from the fuel cell system of Fig. 1,

[0033] Fig. 3 is a schematic view of a movably mounted ultrasonic sensor of an ultrasonic measuring system in the water separator of Fig. 2, Fig. 4 is a schematic view of a first exemplary embodiment of a measuring method according to the invention for the ultrasonic sensor of Fig. 3, and

[0034] Fig. 5 is a schematic view of a second exemplary embodiment of a measuring method according to the invention for the ultrasonic measuring system of the water separator of Fig. 2.

[0035] Identical or functionally equivalent elements are designated by the same reference numeral in Figures 1 to 5.

[0036] Figure 1 schematically shows an exemplary embodiment of a fuel cell system 100 according to the invention. The fuel cell system 100 is shown here purely by way of example with a single fuel cell stack 110 having an anode section 112 and a cathode section 114, although it is of course also possible to provide multiple fuel cell stacks 110. An anode supply section 120 serves to supply anode supply gas to the anode section 112, and a cathode supply section 140 serves to supply cathode supply gas to the cathode section 114. In turn, an anode discharge section 122 serves to discharge anode exhaust gas, and a cathode discharge section 142 serves to discharge cathode exhaust gas.

[0037] As part of this anode discharge section 122, a water separator 10 is integrated therein, which allows water 1 (see Fig. 2) or, more specifically, product water to be separated from the anode exhaust gas 3 (see Fig. 2) in the anode discharge section 122. This separated water 1 can be discharged via a water outlet 12 of the valve device 30, either out of the fuel cell system 100 or recirculated within the fuel cell system 100 for further use.

[0038] During operation, anode feed gas is introduced into the anode section 112 of the fuel cell stack 110 through the anode feed section 120. Spent anode exhaust gas 3 is discharged via the anode discharge section 122 and, as explained, flows through the water separator 10. In addition to being discharged via a so-called purge valve to the environment and / or into the cathode discharge section, as previously mentioned, the anode exhaust gas 3 can also be recirculated via the illustrated passive recirculation device, for example in the form of an ejector device 150. The water separator 10 can of course also be arranged in the recirculation section 130 or even in the anode feed section 120 downstream of the passive recirculation device, here in the form of the ejector device 150.

[0039] Figure 2 shows the water separator 10 from Figure 1 in more detail. The water separator 10 is shown purely schematically as a simple container, which is not typically the case, as it is usually constructed much more complexly to effectively separate the water 1 therein. The illustration serves only to facilitate a better understanding of the invention.

[0040] The water separator 10 comprises a storage volume 4, illustrated here as an example, for storing the water 1 separated from the anode exhaust gas 3. Furthermore, the water separator 10 comprises an inlet opening 16, which is fluidly connected to the anode discharge section 122. In fact, the anode discharge section 122 is also fluidly connected to the water separator 10 at another location. The water separator 10 also comprises an outlet opening 14, which is fluidly connected to the water outlet 12 of the valve device 30 in order to be able to discharge the water 1 separated and stored from the anode exhaust gas 3.

[0041] Finally, the water separator 10 also includes an ultrasonic measuring system 20, which is arranged here, for example, on an upper wall section of the water separator 10 in Fig. 2. The ultrasonic measuring system 20 includes, for example, two ultrasonic sensors 22, 24.

[0042] A first ultrasonic sensor 22 is configured to measure the water level of the water 1. For this purpose, it is aligned in its shown measuring direction 5 towards the water surface of the stored water 1 in the storage volume 4. The water surface has a certain water level 2 that needs to be determined. For this purpose, the first ultrasonic sensor 22 emits ultrasound towards the water surface and receives it after a time dependent on the distance between the first ultrasonic sensor 22 and the water surface. By measuring this time between the emission and reception of the ultrasound, the ultrasonic measuring system 20 can calculate the water level 2. A second ultrasonic sensor 24 is configured to measure the hydrogen concentration of the anode exhaust gas 3.For this purpose, its measuring direction 5 is aligned with a fixed measuring element surface 18, which is exemplified here and is formed on a measuring element of the water separator 10 and projects into the water separator 10. Due to the known distance from the second ultrasonic sensor 24 to the measuring element surface 18, the ultrasonic measuring system 20 can calculate the hydrogen concentration in the anode exhaust gas 3 by measuring the time between the transmission and reception of the ultrasound of the second ultrasonic sensor 24.

[0043] To save space and cost for the water separator 10, the two ultrasonic sensors 22, 24 utilize a common measuring system component 26, which is shown here as an example outside the water separator 10. The measuring system component 26 can, for example, be a measurement control unit including a power supply.

[0044] As an alternative to using two ultrasonic sensors 22, 24 in the ultrasonic measuring system 20, Fig. 3 shows an embodiment in which a single ultrasonic sensor 22 is used to measure both the water fill level 2 and the hydrogen concentration. In order to change the respective measuring direction 5 of the ultrasonic sensor 22, the ultrasonic sensor 22 is movably mounted, in particular rotatably mounted, so that, as shown in Fig. 3, it can perform a rotation R, which can be mediated by a drive of the ultrasonic sensor 22 (not shown). In position P1 of the ultrasonic sensor 22 shown on the left, which is a fill level position P1, the measuring direction 5 is aligned with the water surface. This enables the water fill level 2 to be measured using ultrasound. If the rotation R is now carried out in the direction shown in Fig. 3, the rotation R shown on the right in Fig.3, which is a concentration measuring position P2. In the concentration measuring position P2, the ultrasonic sensor 22 is aligned with its measuring direction 5 towards the particularly stationary measuring element surface 18, as shown in Fig. 2. This enables a measurement of the hydrogen concentration in the concentration measuring position P2. Changing the measuring direction 5 of the ultrasonic sensor 22 thus allows both concentration measurement and fill level measurement. Alternatively or in addition to the movable mounting and movement of the ultrasonic sensor 22, it is also possible to design the measuring element surface 18 to be movable. For example, it is conceivable to move the measuring element surface 18 in front of the ultrasonic sensor 22 to assume the concentration measuring positions P2, so that its measuring direction 5 is aligned therewith.On the other hand, the measuring element surface 18 can then be moved away from the front of the ultrasonic sensor 22 to realign its measuring direction 5 with the water surface. It is therefore also possible not to change the measuring direction 5 itself in order to enable concentration measurement and level measurement with only one ultrasonic sensor 22, but rather to change the surface to be measured in front of the ultrasonic sensor 22—that is, the water surface on the one hand, and the measuring element surface on the other.

[0045] Figures 4 and 5 show embodiments of measuring methods 200 that can be carried out by the ultrasonic measuring systems 20 described here.

[0046] In the measuring method 200 of Fig. 4, the level measurement 202 of the water level 2 of the water 1 and the concentration measurement 204 of the hydrogen concentration of the anode exhaust gas 3 take place one after the other. This measuring method 200 can relate in particular to the design of the ultrasonic measuring system 20 of Fig. 3. In this respect, the level measurement 202 and the concentration measurement 204 can be carried out by one and the same ultrasonic sensor 22. As an optional intermediate step, a movement step 206 can take place between the level measurement 202 and the concentration measurement 204, as shown in Fig. 4. During this optional movement step 206, the previously explained movement of the ultrasonic sensor 22 and / or the measuring element surface 18 can take place in order to switch between the two measuring positions P1, P2. Of course, in the measuring method 200 of Fig.4, the concentration measurement 204 can also be carried out the other way around, followed by the level measurement 202. The measuring method 200 shown can also be repeated, for which purpose a movement step 206 can be carried out between each of the two measuring steps 202, 204 in order to set the required measuring position P1, P2 for the following measuring step 202, 204.

[0047] In the measuring method 200 of Fig. 5, in contrast, the level measurement 202 of the water level 2 of the water 1 by the first ultrasonic sensor 22 of Fig. 2 and the concentration measurement 204 of the hydrogen concentration of the anode exhaust gas 3 by the second ultrasonic sensor 24 take place in parallel. In this respect, this measuring method 200 relates in particular to the exemplary embodiment of the ultrasonic measuring system 20 of the water separator 10 of Fig. 2.

[0048] The above explanations of the embodiments describe the present invention exclusively by way of examples.

[0049] List of reference symbols

[0050] 1 water

[0051] 2 Water level

[0052] 3 Anode exhaust gas

[0053] 4 storage volume

[0054] 5 Measuring direction

[0055] 10 water separators

[0056] 12 Water outlet

[0057] 14 Outlet opening

[0058] 16 Inlet opening

[0059] 18 Measuring element surface

[0060] 20 Ultrasonic measuring system

[0061] 22 first ultrasonic sensor

[0062] 24 second ultrasonic sensor

[0063] 26 Measuring system components

[0064] 30 Valve device

[0065] 100 fuel cell system

[0066] 110 fuel cell stacks

[0067] 112 Anode section

[0068] 114 Cathode section

[0069] 120 Anode feed section

[0070] 122 Anode discharge section

[0071] 130 Recirculation section

[0072] 140 Cathode feed section

[0073] 142 Cathode discharge section

[0074] 150 Ejector device

[0075] 200 measuring methods

[0076] 202 Level measurement

[0077] 204 concentration measurements

[0078] 206 movement step

[0079] P1 Level measuring position

[0080] P2 Concentration measuring position

[0081] R Rotation

Claims

Patent claims Water separator (10) for a fuel cell system (100), wherein the water separator (10) has an inlet opening (16) for an anode discharge section (122) of the fuel cell system (100) for admitting anode exhaust gas (3) from the fuel cell system (100), a storage volume (4) for storing water (1) separated from the anode exhaust gas (3), and an outlet opening (14) for discharging the water (1) stored in the storage volume (4), characterized in that the water separator (10) has an ultrasonic measuring system (20) with at least one ultrasonic sensor (22, 24) for measuring a water level (2) of the water (1) and for measuring a hydrogen concentration of the anode exhaust gas (3).Water separator (10) according to claim 1, characterized in that a first ultrasonic sensor (22) is configured to measure the water level (2) of the water (1) and a second ultrasonic sensor (24) is configured to measure the hydrogen concentration of the anode exhaust gas (3). Water separator (10) according to claim 2, characterized in that the two ultrasonic sensors (22, 24) are arranged on the same wall section of the water separator (10). Water separator (10) according to claim 2 or 3, characterized in that the two ultrasonic sensors (22, 24) are arranged side by side. Water separator (10) according to one of claims 2 to 4, characterized in that the ultrasonic measuring system (20) has at least one measuring system component (26) which the two ultrasonic sensors (22, 24) share at least partially.Water separator (10) according to one of the preceding claims, characterized in that the at least one ultrasonic sensor (22, 24) and / or a measuring element surface (18) of the ultrasonic measuring system (20) is mounted such that it can move between two measuring positions (P1, P2) in order to measure the water level (2) of the water (1) in a level measuring position (P1) of the two measuring positions (P1, P2) and in a concentration measuring position (P2). to measure the hydrogen concentration of the anode exhaust gas (3) in both measuring positions (P1, P2). Water separator (10) according to one of the preceding claims, characterized in that the at least one ultrasonic sensor (22, 24) has a measuring direction (5) aligned with a water surface of the water (1) stored in the storage volume (4) for measuring the hydrogen concentration of the anode exhaust gas (3). Water separator (10) according to one of the preceding claims, characterized in that the at least one ultrasonic sensor (22, 24) has a measuring direction (5) aligned with a measuring element surface (18) of the ultrasonic measuring system (20) in the water separator (10) for measuring the hydrogen concentration. Water separator (10) according to claim 8, characterized in that the measuring element surface (18) is arranged on an element within the storage volume (4).Water separator (10) according to claim 8 or 9, characterized in that the measuring element surface (18) has a predetermined distance from the at least one ultrasonic sensor (22, 24). Fuel cell system (100), comprising. - at least one fuel cell stack (110) with an anode section (112) and a cathode section (114), - an anode supply section (120) for supplying anode supply gas to the anode section (112), - a cathode supply section (140) for supplying cathode supply gas to the cathode section (114), - an anode discharge section (122) for discharging anode exhaust gas, and a cathode discharge section (142) for discharging cathode exhaust gas, wherein a water separator (10) having the features of one of the preceding claims is arranged in the anode discharge section (122). An ultrasonic measuring system (20) for a water separator (10) for a fuel cell system (100), characterized in that the ultrasonic measuring system (20) has at least one ultrasonic sensor (22, 24) for measuring a water level (2) of water (1) in the water separator (10) and for measuring a hydrogen concentration of an anode exhaust gas (3) in the water separator (10). A measuring method (200) for a water separator (10) according to one of claims 1 to 10, for a fuel cell system (100) according to claim 11, or for an ultrasonic measuring system (20) according to claim 12, characterized in that the measuring method (200) comprises the following steps, each of which is carried out by means of the ultrasonic measuring system (20): - Level measurement (202) of the water level (2) of the water (1) and - Concentration measurement (204) of the hydrogen concentration of the anode exhaust gas (3). The measuring method (200) according to claim 13, characterized in that the fill level measurement (202) and the concentration measurement (204) are carried out simultaneously, at least at certain times. The measuring method (200) according to claim 13, characterized in that the fill level measurement (202) and the concentration measurement (204) are carried out at different times from one another.