AT524996A1 - Vacuum device for generating a vacuum in a test object on a fuel cell test stand - Google Patents

Abstract

The present invention relates to a vacuum device (10) for generating a vacuum in a test specimen (P) on a fuel cell test stand (100), having an ejector device (20) with a secondary connection (24) for sucking in secondary fluid (SF), a primary connection (22) for generating negative pressure as secondary pressure (SP) at the secondary connection (24) by introducing a primary fluid (PF) under a primary pressure (PP) at the primary connection (22) and an ejector outlet (26) for the outlet of a mixed fluid (MF) of primary fluid (PF) and secondary fluid (SF), further having a primary path (21) upstream of the primary port (22) for a fluid-communicating connection with a primary fluid source (30) and a secondary path (23) upstream of the secondary port (24) for a fluid-communicating connection with an exhaust gas section (AA) of the test specimen (P) for receiving exhaust gas (AG) as a secondary fluid (SF).

Description

Vacuum device for generating a vacuum in a test specimen

a fuel cell test stand

The present invention relates to a vacuum device for generating a vacuum in a test specimen on a fuel cell test stand, a test stand structure with such a vacuum device and a test method

use of such a vacuum device.

It is known that fuel cell systems and their subsystems and components should be subjected to regular or random tests during development, but also at the end of a production line. Test benches are usually used for this, which carry out these tests. A large number of subsystems and components of fuel cell systems are usually operated in the regular operation of the fuel cell system in negative pressure. In this respect, it is desirable that a negative pressure is also generated in the respective subsystem or the respective component when testing these subsystems and components. In order to achieve a negative pressure on test benches, blower devices are usually used. These fan devices have a suction side and a pressure side. In the known solutions, they are arranged with their suction side on the exhaust gas sections of the test objects and in this way

the desired negative pressure is available.

A disadvantage of the known solutions is that such blower devices are usually of relatively complex construction and, in particular, can only be made heat-resistant to a very limited extent. If test specimens are tested on test benches as components or subsystems of fuel cell systems, this often also applies to high-temperature fuel cell systems, such as SOFC/SOEC fuel cell systems. This means that high temperatures of up to 1000 C° occur during operation. In order to be able to carry out the test under realistic operating conditions on the test bench, similarly high temperatures are also required on the test bench. The result of this is that the known solutions with fans that generate underpressure cannot be used, or can only be used to a very limited extent, since these high temperatures would quickly lead to a defect. In order to still be able to carry out a meaningful test, in the case of known test benches, an overpressure is applied instead of a negative pressure in order to at least

to perform a leak test. However, the complete one is missing here

respective test sample is available.

It is the object of the present invention to at least partially eliminate the disadvantages described above. In particular, it is the object of the present invention to provide subsystems and components as test specimens for high-temperature fuel cells under realistic conditions in a cost-effective and simple manner

can also be tested with negative pressure.

The above object is achieved by a vacuum device having the features of claim 1, a test stand assembly having the features of claim 13 and a testing method having the features of claim 14. Further features and details of the invention result from the dependent claims, the description and the drawings . Features and details that are described in connection with the vacuum device according to the invention also apply, of course, in connection with the test bench structure according to the invention and the test method according to the invention and vice versa, so that the disclosure of the individual aspects of the invention is always changing.

self-reference is or can be made.

The core idea of the invention is that a vacuum device for generating a vacuum in a test specimen on a fuel cell test bench is made available. This vacuum device is characterized by the presence of an ejector device with a secondary connection for sucking in secondary fluid. Furthermore, this ejector device is equipped with a primary connection for generating negative pressure as a secondary pressure at the secondary connection by introducing a primary fluid under a primary pressure at the primary connection. On the outlet side, the ejector device is equipped with an ejector outlet for discharging a mixed fluid made up of primary fluid and secondary fluid. The vacuum device of the present invention also includes a primary path, also upstream of the primary port, for fluidly communicating with a source of primary fluid. Further, the vacuum device is provided with a secondary path upstream of the secondary port for fluidly communicating with an exhaust portion of the test specimen

for receiving exhaust gas as a secondary fluid.

to be able to specify fluid.

The core idea according to the invention is now based on using this ejector device with the negative pressure as the secondary pressure in order to achieve a suction power, and thus a negative pressure, in a test specimen. The test object, for example a fuel cell stack or an individual fuel cell, is brought into fluid communication with the secondary path on the fuel cell test bench with its exhaust gas section. The ejector device is then operated with a primary fluid. In the simplest case, this can be a compressed air connection, so that pressurized air flows as the primary fluid from a compressed air connection as the primary fluid source via the primary path into the primary connection of the ejector device. The pressure of this compressed air leads to the ejector effect described and the formation of the negative pressure as secondary pressure at the secondary connection. The negative pressure is transmitted through the fluid-communicating connection to the exhaust section of the test object and in this way draws in exhaust gas as a secondary fluid.

A decisive advantage of the present invention is that an ejector device is designed as a passive vacuum device, in contrast to the previously used rotary fan devices. In addition to the reduction in complexity and the simplified controllability, the omission of moving components leads in particular to the fact that such an ejector device can be constructed inexpensively and easily from heat-resistant components. This leads to,

that in addition to a simple and inexpensive way to create the vacuum

testify that this is also possible when the test specimen is used for real conditions in

Must be used in high-temperature operations. So it is possible to

gate device in a vacuum device according to the invention for a temperature

ture resistance up to 1000° C or more, so that the testing process on

DUT can take place in such a temperature range.

It should also be pointed out that in an embodiment according to the invention, the fluids mentioned are preferably all gaseous. The primary fluid is therefore in particular a primary gas and the secondary fluid is in particular a secondary gas. Within the scope of the present invention, the aim is to achieve a negative pressure within the test specimen with the aid of the negative pressure device. For safety reasons, components such as fuel cells or entire fuel cell stacks and other components such as reformer devices or the like in fuel cell systems are often operated at negative pressure relative to the ambient pressure in order to prevent gases from escaping in the event of a leak with a high level of certainty. With a vacuum device according to the invention, this vacuum operation can now be tested on a test bench in a cost-effective and simple manner even during high-temperature operation.

It can be advantageous if, in a vacuum device according to the invention, the primary path has a controllable primary valve device for controlling the primary pressure. Such a controllable primary valve device is used in particular, at least qualitatively, to be able to switch the ejector device on and off. In particular when a simple primary fluid source, such as a compressed air connection, is used, such a qualitatively switching primary valve device can provide a switching option. However, even quantitative checking is preferably possible using the primary valve device. This makes it possible not only to switch the ejector device on and off, but also to quantitatively influence the primary pressure with a throttle function, so to speak. A fully open, quantitatively controllable primary valve thus leads to a maximum applied primary pressure, while a partially closed primary valve device results in a correspondingly reduced primary pressure. Since there is a connection, often linear, between the primary pressure and the secondary pressure, the secondary pressure can also be directly influenced in this way and

gen a check of the negative pressure to be generated in the test object.

tion of primary valve device and secondary valve device.

Further advantages can be achieved if, in a vacuum device according to the invention, a pressure sensor for detecting the primary pressure is arranged in the primary path and/or a pressure sensor for detecting the secondary pressure is arranged in the secondary path. The detection of pressures in the individual paths means that a control loop can be formed in addition to a pure control functionality of the control. It is therefore possible to specify setpoint values for the primary pressure and/or the secondary pressure, to carry out corresponding control interventions on the valve devices described and to record their effect using the pressure sensors. As an alternative or in addition to the pressure sensors mentioned, it is also possible to use flow sensors in order to measure the volume flows of primary fluid and

Also to detect secondary fluid.

Further advantages can be achieved if at least one additional ejector device is provided in a vacuum device according to the invention, with an additional secondary connection for sucking in secondary fluid. This additional ejector device is further designed with an additional primary connection for generating negative pressure at the additional secondary connection by introducing a primary fluid under a primary pressure at the additional primary connection. Finally, this additional ejector device is also configured with an additional ejector outlet for the outlet of a mixed fluid made up of primary fluid and secondary fluid. The secondary path in this embodiment is equipped with a splitting section for splitting

of the exhaust gas from the exhaust section of the test object as a secondary fluid on the secondary

for the exhaust gas section of the test object.

In a vacuum device according to the previous paragraph, it can be advantageous if separate and controllable primary valve devices are arranged in the primary path to the primary connection and in an additional primary path to the additional primary connection, for controlling the respective primary pressure. Similar to the explanation for a single ejector device, a qualitative or quantitative check of the primary pressures can be used separately for the additional ejector device and the regular ejector device. Especially with quantitative switching options, this leads to a very high level of flexibility for a wide variety of test situations and test objects. It should also be pointed out here that the additional ejector device communicates fluidly with the same primary fluid source or with a separate additional primary fluid source

can be connected.

It is also advantageous if, in a vacuum device according to the invention, a secondary path of the ejector device is arranged as a separate additional secondary path upstream of the additional secondary connection, for a fluid-

communicating connection with an additional exhaust section of the test item for

will.

It is also advantageous if, in a vacuum device according to the invention, a fluid aftertreatment device for aftertreatment of the mixed fluid is arranged downstream of the ejector outlet, in particular also downstream of an additional ejector outlet. This can be, for example, a catalytic converter device, an afterburner device, a cooling device, a heat exchanger device or the like. Of course, several fluid post-treatment devices can also be connected in parallel or in series. Such a fluid after-treatment device is preferably provided jointly for all ejector devices and additional ejector devices of the vacuum

contraption.

Further advantages can be achieved if, in a vacuum device according to the invention, the ejector device has, in addition to the secondary connection, a supplementary secondary connection with a supplementary secondary path arranged upstream for introducing supplementary exhaust gas from a supplementary exhaust gas section as secondary fluid into the supplementary secondary connection. This is one way of using a single ejector device to supply different exhaust gas sections of the test specimen with negative pressure. Both on the exhaust section

as well as at the supplementary exhaust gas section, negative pressure is created via secondary pressure

provided. However, the negative pressure divides which of one and the same

Ejector device is generated, on the correspondingly larger number of exhaust

cut up. Here, too, qualitatively or quantitatively switchable

til devices a controllability as well as with the use of pressure sensors

controllability can be made available.

It is also advantageous if a secondary valve device for controlling the secondary pressure is arranged in the secondary path and/or in the supplementary secondary path in a vacuum device according to the invention. Secondary valve devices are preferably provided in all secondary paths, so that a separate control of the different vacuums despite the use of a

common ejector can be achieved.

It is also advantageous if, in a vacuum device according to the invention, at least the fluid-carrying sections of the ejector device, in particular also an additional ejector device, are designed to be temperature-resistant, to temperatures of up to 900°C to 1000°C. This is particularly inexpensive and easily possible, since an ejector device is a passive component without rotating components. This is particularly advantageous for the use of test specimens as components or subsystems of high-temperature fuel cell systems, so that the ejector device generates the negative pressure for the test specimen on the hot exhaust gas side of a fuel cell system

can provide.

It is also advantageous if, in a vacuum device according to the invention, the primary path has a compressor device for increasing the primary pressure. If a compressed air source or other primary fluid source is not sufficient to provide a sufficient primary pressure for a desired secondary pressure as negative pressure, a compressor device can result in a further increase in the primary pressure. While the valve devices described so far can only involve a throttling function and thus a reduction in a primary pressure or a secondary pressure, a compressor device now allows the primary pressure to be actively increased. Such a compressor device can be part of the primary path and/or part of a primary fluid source.

Also subject matter of the present invention is a test bench construction for a

Test bench operation for testing a test item. Such a test stand structure has

equipped with a fuel cell test stand.

Another subject matter of the present invention is a test method for a vacuum test of a test specimen in a test stand assembly according to the invention,

comprising the following steps:

- Supplying a primary connection of the ejector device with a pri-

thermal fluid under primary pressure, — operation of the test item in a test bench operation,

- Generation of a negative pressure at the exhaust section of the test specimen via the fluid-communicating connection to the secondary connection of the ejector device.

A test method according to the invention brings with it the same advantages as have been explained in detail with reference to a vacuum device according to the invention and a test bench structure according to the invention. A core idea is that the secondary pressure is specified and generated as a target parameter and thus as a defined negative pressure within the test object with such a test method

can be.

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

Fig. 1 an embodiment of a vacuum system according to the invention

direction,

Fig. 2 shows the vacuum device of Figure 1 in an inventive

Ren test bench construction,

3 shows a further test stand structure according to the invention, FIG. 4 shows a further test stand structure according to the invention, FIG. 5 shows a further test stand structure according to the invention, and FIG. 6 shows a further test stand structure according to the invention.

The simplest configuration of a vacuum device 10 is shown schematically in FIG. The core of this vacuum device 10 is an ejector device 20. The primary connection 22 of this ejector device 20 is connected in a fluid-communicating manner to a primary path 21, which conveys primary fluid PF from a primary fluid source 30. The primary fluid source 30 can be a compressed air connection, for example. The inflow of the primary fluid PF via the primary connection 22 into the ejector device 20 generates a negative pressure at the secondary connection 24 of the same as secondary pressure SP, which sucks in secondary fluid SF via a secondary path 23 . The mixture of primary fluid PF and secondary fluid SF is discharged again from the ejector outlet 26 as mixed fluid MF. The vacuum generation that is possible in this way can now be used on a fuel cell test stand 100

be as shown in Figure 2 and explained in more detail.

The embodiment of the vacuum device 10 is used in FIG. This can be a simple component of a fuel cell system which, during operation, generates hot exhaust gas via an exhaust gas section AA. This mode of operation is simulated on the test stand 100, so that the hot exhaust gas AG exits via the exhaust gas section AA of the test object P. In order to be able to provide the desired negative pressure for a realistic test situation within the test object P, the primary fluid PF is applied under primary pressure PP to the primary connection 22 of the ejector device 20, so that a secondary pressure SP is created at the secondary connection 24 as a negative pressure for sucking in the exhaust gas AG as Secondary fluid SF sets. Here again it is easy to see that very hot exhaust gas AG, for example up to 1000° C., can also be used as secondary fluid SF, since the ejector device 20 can be made heat-resistant in a simple and cost-effective manner.

can be switched both qualitatively and quantitatively.

FIG. 4 shows a variant in which there is greater freedom for the controllability of the vacuum device 10 . This is now additionally equipped with an additional ejector device 70 which can be structurally identical to or different from the regular ejector device 20 . The exhaust gas section AA makes the hot exhaust gas AG available again as a secondary fluid SF, which can now also be divided into the additional secondary path 73 via a dividing section 29 . Identical to the regular ejector device 20, primary fluid PF can now enter an additional primary connection 72 of the additional ejector device 70 via an additional primary path 71 from the same or another primary fluid source 30 and make the ejector function available in order to generate negative pressure as secondary pressure SP at the additional To provide secondary outlet 7/4 for sucking in the hot exhaust gas AG. Here, too, the mixed mixed

fluid MF output again from an additional ejector outlet 7/6.

In addition to the improved controllability and greater variability through the use of, in particular, different ejector devices 20 and additional ejector devices 70, a common fluid post-treatment device is also required here.

device 80, for example as a catalyst, provided.

Further advantages are shown in FIG. 5, in which an additional ejector device 70 is also used as in FIG. However, this is connected to a more complex test item P, which has two separate gas trains, so that not only exhaust gas AG exits from an exhaust gas section AA, but also separate additional exhaust gas ZAG from an additional exhaust gas section ZAA. Thus, completely separately from each other, the additional ejector device 70 the vacuum situation in the additional exhaust gas section ZAA of the test specimen and the ejector device 20 the

Check the vacuum situation in the normal exhaust gas section AA of test object P.

fluid PF and can set a defined form as primary pressure PP.

The above explanation of the present invention describes the present

de Invention solely in the context of examples.

Reference List

10 vacuum device

20 ejector device

21 primary path

22 primary port

23 secondary path

24 secondary connection

26 ejector outlet

27 supplement secondary path

28 Supplementary secondary connection 29 Splitting section

30 primary fluid source

40 primary valve assembly

50 secondary valve device 60 pressure sensor

70 auxiliary ejector device 71 auxiliary primary path

72 Auxiliary Primary Connection

73 Auxiliary Secondary Path

74 Auxiliary secondary connection 76 Auxiliary ejector outlet

80 fluid aftertreatment device

90 compressor device

100 fuel cell test bench 200 test bench assembly

P examinee

AA — exhaust section

ZAA additional exhaust section

EAA supplementary exhaust gas section AG exhaust gas

ZAG additional exhaust

EAG supplementary exhaust gas

PF primary fluid

PP Primary pressure SF Secondary fluid SP Secondary pressure MF Mixed fluid

Claims (1)

patent claims 1. Vacuum device (10) for generating a vacuum in a test specimen (P) on a fuel cell test bench (100), having an ejector device (20) with a secondary connection (24) for sucking in secondary fluid (SF), a primary connection (22) for generating negative pressure as secondary pressure (SP) at the secondary connection (24) by introducing a primary fluid (PF) under a primary pressure (PP) at the primary connection (22) and an ejector outlet (26) for the outlet of a mixed fluid (MF) from primary fluid (PF) and secondary fluid (SF), characterized by a primary path (21) upstream of the primary port (22) for fluid communication with a primary fluid source (30) and a secondary path (23) upstream of the secondary port (24) for fluid communication with an exhaust section (AA) of the test object (P) for absorbing exhaust gas (AG) as secondary fluid (SF). 2. Vacuum device (10) according to claim 1, characterized in that the primary path (21) has a controllable primary valve device (40) for controlling the primary pressure (PP). 3. Vacuum device (10) according to one of the preceding claims, characterized in that the secondary path (23) has a controllable secondary valve device (50) for controlling the secondary pressure (SP) having. 4. Vacuum device (10) according to any one of the preceding claims, characterized in that in the primary path (21) a pressure sensor (60) for detecting the primary pressure (PP) and / or in the secondary path (23) a pressure sensor (60) for detecting the secondary pressure (SP) is arranged. 5. Vacuum device (10) according to one of the preceding claims, characterized in that at least one additional ejector device (70) is provided with an additional secondary connection (47) for sucking in secondary fluid (SF), an additional primary connection (72) for creating a vacuum at the auxiliary secondary port (74) by introducing a primary fluid (PF) under a primary pressure (PP) at the auxiliary primary port (72) and an auxiliary ejector outlet (76) for discharging a mixed fluid Secondary connection (74) of the additional ejector device (70). 6. Vacuum device (10) according to claim 5, characterized in that separate and controllable primary valve devices (40) are arranged in the primary path (21) to the primary connection (22) and in an additional primary path (71) to the additional primary connection (72). for a check of respective primary pressure (PP). 7. Vacuum device (10) according to one of Claims 5 or 6, characterized in that an additional secondary path (73) separate from the secondary path (23) of the ejector device (20) is arranged upstream of the additional secondary connection (74) for a fluid-communicating connection with a Additional exhaust gas section (ZAA) of the test specimen (P) for receiving additional exhaust gas (ZAG) as secondary fluid (SF). 8. Vacuum device (10) according to any one of the preceding claims, characterized in that downstream of the ejector outlet (26), in particular also downstream of an additional ejector outlet (76), a fluid aftertreatment device (80) for aftertreatment of the mixed fluid (MF) is arranged. 9. Vacuum device (10) according to one of the preceding claims, characterized in that the ejector device (20) in addition to the secondary connection (24) has a supplementary secondary connection (28) with a supplementary secondary path (27) arranged upstream for the introduction of supplementary -Exhaust gas (EAG) from a supplementary exhaust gas section (EAA) as a secondary fluid (SF) in the supplementary secondary connection (28). 10. Vacuum device (10) according to claim 9, characterized in that a secondary valve device (50) for controlling the secondary pressure (SP) is provided in the secondary path (23) and/or in the supplementary secondary path (27). is arranged. (70), are designed to be temperature-resistant to temperatures of up to 1000 °C. 12. Vacuum device (10) according to any one of the preceding claims, characterized in that the primary path (21) is a compressor device device (90) for an increase in the primary pressure (PP). 13. Test bench assembly (200) for test bench operation for testing a test object (P), having a fuel cell test bench (100) with a test object (P) arranged thereon, further having a vacuum device (10) with the features of one of claims 1 to 12 , which is connected to the test specimen (P) in a fluid-communicating manner. 14. Test method for a negative pressure test of a test specimen (P) in a test stand assembly (200) with the features of claim 13, having the fol- following steps: - supplying a primary connection (22) of the ejector device (20) with a primary fluid (PF) under primary pressure (PP), — operation of the test item (P) in a test bench operation, - Generating a negative pressure on the exhaust section (AA) of the test specimen (P) via the fluid-communicating connection to the secondary connection (24) of the ejector device (20).