SENSOR DEVICE FOR A FUEL CELL SYSTEM

Abstract

The present invention relates to a sensor device (10) for a fuel cell system (100) for determining a purging parameter (SP) for controlling a purging process of the fuel cell system (100), comprising a first flow channel (20) for arranging in an anode feed section (122) of an anode section (120) of a fuel cell stack (110) and a second flow channel (130) for arranging in a recirculation section (126) of the anode section (120) of the fuel cell stack (110), which are separated from each other, at least in sections, by means of a gas-tight membrane (40), wherein the membrane (40) is designed to be permeable for protons and has an electrode section (42, 44) on both sides, as well as comprising a measuring device (50) for determining a fuel concentration difference between the first flow channel (20) and the second flow channel (30) as a purging parameter (SP) based on an electrical voltage between the two electrode sections (42, 44).

Claims

1. Sensor device (10) for a fuel cell system (100) for determining a purging parameter (SP) for controlling a purging process of the fuel cell system (100), comprising a first flow channel (20) for arranging in an anode feed section (122) of an anode section (120) of a fuel cell stack (110) and a second flow channel (130) for arranging in a recirculation section (126) of the anode section (120) of the fuel cell stack (110), which are separated from each other, at least in sections, by means of a gas-tight membrane (40), wherein the membrane (40) is designed to be permeable for protons and has an electrode section (42, 44) on both sides, as well as comprising a measuring device (50) for determining a fuel concentration difference, in particular of hydrogen, between the first flow channel (20) and the second flow channel (30) as a purging parameter (SP) based on an electrical voltage between the two electrode sections (42, 44).

2. Sensor device (10) according to claim 1, characterised in that the electrode sections (42, 44) cover the entire or substantially the entire membrane (40) on both sides.

3. Sensor device (10) according to claim 1, characterised in that the first flow channel (20) and the second flow channel (30) are identical or substantially identical in design, in particular with respect to the flow conditions.

4. Sensor device (10) according to claim 1, characterised in that the first flow channel (20) and/or the second flow channel (30) have at least one actuating device (60) for controlling the flow conditions in the respective flow channel (20, 30).

5. Sensor device (10) according to claim 4, characterised in that the at least one actuating device (60) comprises at least one of the following modules: pressure module for varying the gas pressure in the respective flow channel (20, 30) mass flow module for varying the mass flow in the respective flow channel (20, 30).

6. Sensor device (10) according to claim 1, characterised in that the membrane (40) has on at least one side, in particular on both sides, preferably on the respective electrode section (42, 44), a catalyst layer for oxidising gas components, in particular hydrogen.

7. Sensor device (10) according to claim 1, characterised in that the membrane (40) is designed to be electrically insulating.

8. Sensor device (10) according to claim 1, characterised in that the first flow channel (20) and the second flow channel (30) flow along the membrane (40) in parallel.

9. Fuel cell system (100), having: at least one fuel cell stack (110) with an anode section (120) and a cathode section (130), an anode feed section (122) for feeding anode feed gas to the anode section (120), a cathode feed section (132) for feeding cathode feed gas to the cathode section (130), an anode discharge section (124) for discharging at least a part of the anode exhaust gas, a cathode discharge section (134) for discharging cathode exhaust gas, a recirculation section (126) for returning at least a part of the anode exhaust gas into the anode feed section (122), wherein a sensor device (10) with the features of claim 1, is also provided and the anode feed section (122) contains the first flow channel (20) of the sensor device (10) and the recirculation section (126) contains the second flow channel (30) of the sensor device (10).

10. Fuel cell system (100) according to claim 9, characterised in that a mixing section (140) is arranged downstream of the second flow channel (30) in the flow direction of the recirculated anode exhaust gas to introduce the recirculated anode exhaust gas into the anode feed section (122).

11. Fuel cell system (100) according to claim 10, characterised in that the mixing section (140) in the anode feed section (122) is arranged downstream of the first flow channel (20) in the flow direction of the anode feed gas.

12. Fuel cell system (100) according to claim 10, characterised in that the mixing section (40) in the anode feed section (122) is arranged upstream of the first flow channel (20) in the flow direction of the anode feed gas.

13. Method for controlling a purging process of a fuel cell system (100) with the features of claim 9, having the following steps: determining a purging parameter (SP) by means of the sensor device (10), comparing the determined purging parameter (SP) with a specified value (VW), carrying out a purging process on the basis of the comparison.

14. Method according to claim 13, characterised in that a secondary parameter (SE), in particular in the form of a nitrogen concentration in the second flow channel (30), is determined on the basis of the purging parameter (SP).

Description

[0043] FIG. 1 shows an embodiment of a sensor device according to the invention,

[0044] FIG. 2 shows a further embodiment of a sensor device according to the invention,

[0045] FIG. 3 shows an embodiment of a fuel cell system according to the invention,

[0046] FIG. 4 shows a further embodiment of a fuel cell system according to the invention,

[0047] FIG. 5 shows a further embodiment of a fuel cell system according to the invention,

[0048] FIG. 6 shows a schematic representation of the method according to the invention.

[0049] FIG. 1 shows, schematically, the basic structure of a sensor device according to the invention. The sensor device has two individual cells which are characterised by a first flow channel 20 and a second flow channel 30. The first flow channel 20 is part of an anode feed section 122 and the second flow channel 30 is part of a recirculation section 126. Preferably, pure anode feed gas, for example pure hydrogen, flows through the first flow channel 20. Accordingly, recirculation gas contaminated by the anode exhaust gas is conducted through the second flow channel 30, so that a chemical concentration difference is established between hydrogen in the first flow channel 20 and in the second flow channel 30. In this embodiment, as shown in FIG. 1, the two flow channels 20 and 30 are separated by a gas-tight membrane 40. However, protons can penetrate through this membrane 40, so that a chemical concentration difference leads to an electrically measurable voltage between the first flow channel 20 and the second flow channel 30. This voltage is picked up via the electrode sections 42 and 44 arranged on both sides of the membrane 40 and can be detected by the measuring device 50. In the measuring device 50, the detected concentration difference can now be output as the purging parameter SP, or the measured voltage value can also be output directly. As can be clearly seen in FIG. 1, in this case the first flow channel 20 and the second flow channel 30 flow in parallel.

[0050] FIG. 2 shows a further development of a sensor device according to the invention. This is essentially based on the solution shown in FIG. 1. However, actuating devices 60 are additionally provided here, which are in the form of pump devices. This makes it possible to vary the flow conditions in the first flow channel 20 and in the second flow channel 30. Especially with different load requirements, but also with different recirculation quantities, an adjustment of the flow conditions in the other flow channel 20 or 30 can be carried out in this way, so that an equalisation, and in particular an equalisation of the flow conditions between the two flow channels 20 and 30 is possible.

[0051] FIG. 3 shows the integration of a sensor device 10 according to the invention in a fuel cell system 100 according to the invention. This is represented here schematically, with a fuel cell stack 110 with an anode section 120 and a cathode section 130. The anode section 120 is provided with an anode feed section for feeding anode feed gas and an anode discharge section 124 for discharging anode exhaust gas. In the same way, the cathode section 130 is designed with a cathode feed section 132 for feeding cathode feed gas and a cathode discharge section 134 for discharging cathode exhaust gas. As has already been explained, a residue of hydrogen is still present in the anode exhaust gas of the anode section 120 which is not discharged into the environment, but is instead intended to be recycled. This recycling is achieved through the recirculation of at least a part of the anode exhaust gas with the help of the recirculation section 126.

[0052] FIG. 3 shows how a sensor device 10 is integrated into the anode feed section 122 and the recirculation section 126. The anode exhaust gas recirculated through the recirculation section 126 is conducted into the second flow channel 30 and is present there in a concentration difference with respect to the anode feed gas of the first flow channel 20. Naturally, it is also possible to feed the recirculation gas downstream of the sensor device 10. This makes possible the integral determination of the concentration difference, so that a purging or bleeding process can be carried out with targeted precision.

[0053] FIG. 4 shows a further development of the embodiment shown in FIG. 1. In this embodiment, regulating valves or control valves are provided in the feed and discharge paths to the sensor device 10 as an actuating device 60 to equalise the flow conditions in the first flow channel 20 and in the second flow channel 30. A mixing section 140 is also provided which allows a mixing of the recirculation gas with the pure feed gas to be carried out with targeted precision. Naturally, the mixing section 140 can also be arranged downstream of the second flow channel 20 in the anode feed section 122.

[0054] FIG. 5 shows an embodiment with a further improvement of the fuel cell system 100. Thus, two sensor devices 10 are provided here which carry out their determination at two different points in relation to the mixing section 140. Thus, the left-hand sensor device 10 is able to determine the concentration difference between the pure anode feed gas and the recirculation gas. The right-hand sensor device 10 allows a determination between the recirculation gas and the already mixed anode feed gas. This means that an even more precise integral determination and thus an even more precise control of the purging and/or bleeding processes can be made available.

[0055] FIG. 6 shows, schematically, how a method according to the invention can be carried out. A hundred percent hydrogen concentration H2 is preferably present in the first flow channel 20. The second flow channel 30 is contaminated by a residue, for example by water vapour and/or by nitrogen and/or by carbon monoxide and/or carbon dioxide, so that the hydrogen concentration H2 is lower than in the first flow channel 20. The hydrogen concentration can now be determined as the purging parameter SP. On comparing this with a specified value VW according to FIG. 6, it is noticeable that the hydrogen concentration, as the purging parameter SP, has fallen below the specified value VW, so that the residue and thus the degree of contamination is too high and a purging process is necessary. In the same way, in addition or alternatively, it is possible to determine a secondary parameter SP for the residue, for example a nitrogen concentration. This can also be compared with a specified value VW, which according to FIG. 6 is, in this example, too high, so that too much contamination is present and a purging process is likewise necessary. Naturally, these two comparison steps can also be combined with each other in a method according to the invention.

[0056] The above explanation describes the present invention exclusively in the context of examples. Naturally, individual features of the present embodiments can be combined with each other freely without departing from the scope of the present invention.

LIST OF REFERENCE SIGNS

[0057] 10 sensor device [0058] 20 first flow channel [0059] 30 second flow channel [0060] 40 membrane [0061] 42 electrode section [0062] 44 electrode section [0063] 50 measuring device [0064] 60 actuating device [0065] 100 fuel cell system [0066] 110 fuel cell stack [0067] 120 anode section [0068] 122 anode feed section [0069] 124 anode discharge section [0070] 126 recirculation section [0071] 130 cathode section [0072] 132 cathode feed section [0073] 134 cathode discharge section [0074] 140 mixing section [0075] SP purging parameter [0076] SE secondary parameter [0077] VW specified value