| JP2008084730 | FUEL CELL SYSTEM |
| WO/2007/137004 | FUEL CELL HYBRID POWER GENERATION SYSTEM AND METHOD FOR GAS DISTRIBUTION SYSTEMS |
| JP2004010411 | METHOD FOR STARTING AND OPERATING REFORMING DEVICE |
STEIN, Boris (Bissinger Strasse 2, Kirchheim unter Teck, 73230, DE)
MÜLLER, Ralf (Glückaufstr. 53, Lobstaedt, 04552, DE)
BAUR, Thomas (Gartenstrasse 18, Weilheim, 73235, DE)
BUCHAUER, Bernd (Bruckwiesenstrasse 6/2, Hattenhofen, 73110, DE)
SCHERRBACHER, Klaus (Schulstrasse 58, Deggingen, 73326, DE)
FORD GLOBAL TECHNOLOGIES, LLC (330 Town Center Drive, Suite 800 SouthDearborn, MI, 48126, US)
GERHARDT, Stefan (Erlenweg 2, Westerstetten, 89198, DE)
STEIN, Boris (Bissinger Strasse 2, Kirchheim unter Teck, 73230, DE)
MÜLLER, Ralf (Glückaufstr. 53, Lobstaedt, 04552, DE)
BAUR, Thomas (Gartenstrasse 18, Weilheim, 73235, DE)
BUCHAUER, Bernd (Bruckwiesenstrasse 6/2, Hattenhofen, 73110, DE)
SCHERRBACHER, Klaus (Schulstrasse 58, Deggingen, 73326, DE)
Patent Claims
1. A pipe assembly having a metal pipe (10) and having a connecting element (22) coupled to the metal pipe (10), to which connecting element a sensor (12) may be or is connected, a heating unit (24) being provided in or on the connecting element (22), characterized in that the connecting element (22) is thermally insulated relative to the metal pipe (10).
2. The pipe assembly as claimed in claim 1, characterized in that plastics material is arranged between connecting element (22) and metal pipe (10).
3. The pipe assembly as claimed in claim 2, characterized in that the plastics material is provided in the form of a plastics plate (28).
4. The pipe assembly as claimed in claim 2 or 3, characterized in that the plastics material is Teflon.
5. The pipe assembly as claimed in one of claims 2 to 4, characterized in that the plastics material is polyphenylene sulfide.
6. The pipe assembly as claimed in claim 1 or 2, characterized in that a thermally insulating foam is arranged between connecting element and metal pipe.
7. The pipe assembly as claimed in claim 2, characterized in that the pipe assembly comprises a pipe portion, which consists at least in part of plastics and to which the connecting element (22) is connected.
8. The pipe assembly as claimed in one of the preceding claims, in which the metal pipe (10) is made from aluminum.
9. The pipe assembly as claimed in one of the preceding claims, in which a sensor connected to the connecting element (22) is a pressure sensor (12), which comprises an inlet (26) in communicative connection with an inner chamber of the metal pipe (10).
10. A fuel cell system having the pipe assembly as claimed in one of the preceding claims for the passage of gas.
11. The fuel cell system as claimed in claim 10, characterized in that the pipe assembly is provided in the anode circuit. |
PIPE ASSEMBLY FOR FUEL CELL SYSTEM
The invention relates to a pipe assembly according to the preamble of patent claim 1.
Such a pipe assembly is used in a fuel cell system, for example in the "anode circuit". Coupled to a metal pipe is a connecting element, to which a sensor may be or is connected. The connecting element, conventionally known as a "sensor port", is conventionally provided by making a tee in the pipe assembly, the connecting element as a rule comprising a thread for allowing connection of a sensor. Conventionally, a pressure sensor is connected to the connecting element.
When operating a fuel cell system, water may accumulate in the pipe assembly, precisely in the area of the connecting element. At suitably cold ambient temperatures the condensed water may freeze and thereby impair functioning of the sensor or make it completely impossible. A pressure sensor, for example, has to be connected via the connecting element to the inner chamber of the metal pipe of the pipe assembly, to make it at all possible for it to measure the pressure of the gas passing through the metal pipe. Ice may close up a corresponding opening in the connecting element, which leads to the pressure sensor, or indeed an opening in the pressure sensor itself.
This is dealt with by providing a heating unit on the connecting element. Before the fuel cell system is started up, the heating unit may cause the ice to melt. The provision of such a heating unit is described in JP 2005164538 A, for example.
This arrangement functions satisfactorily, if the metal pipe consists of stainless steel. The heating unit may then heat the pressure sensor up to as much as 100 0 C. In this way, any
blockage of the pressure sensor by ice may be eliminated, and cold starting of the fuel cell system is thus not impeded.
It is now desired to use aluminum pipes in the anode circuits of fuel cell systems. However, it has been demonstrated that when aluminum pipes are used in a pipe assembly according to the preamble of patent claim 1 the heating unit no longer functions effectively.
It is the object of the invention to enable cold starting of a fuel cell system even when a pipe assembly with aluminum pipes is used.
The object is achieved by a pipe assembly having the features as claimed in patent claim 1 and a fuel cell system having such a pipe assembly for the passage of gas as claimed in patent claim 10.
According to the invention, the connecting element is thermally insulated relative to the metal pipe.
The invention is based on the recognition that the aluminum pipe dissipates the heat provided by the heating unit too well. Measurements have shown that, without the provision of thermal insulation, the pressure sensor can only be warmed up to a temperature of 65°C, which is insufficient for deicing.
In a preferred embodiment of the invention, a plastics material is arranged between connecting element and metal pipe, since plastics are typically particularly poorly thermally conductive.
The plastics material may be provided in the form of a plastics plate. A plastics plate may be readily made from Teflon or polyphenylene sulfide, which have a particularly good thermally insulating effect.
Instead of a plastics plate, a thermally insulating foam may also be arranged between connecting element and metal pipe. In this way, shaping in the connection area may be influenced. Foam is also simple to provide.
Finally, the plastics material may even be provided directly in the form of a plastics pipe portion - the connecting element is then arranged directly on this plastics pipe portion and no longer on the metal pipe. There is thus a transition from the metal pipe to the plastics pipe portion with the connecting element and in turn a transition from the plastics pipe portion back to a metal pipe.
In the event of use in the anode loop, the plastics pipe may be coated with a metal in the plastics pipe portion to produce a conductive connection between the one and the other metal pipe: a thin metal layer does not impair thermal insulation.
The invention may be used with any desired metal pipes, use of the concept according to the invention as described above being necessary if the metal pipe is made from aluminum.
The invention may be used with connection options for any desired sensors. As described above, the problem arises more intensely if a sensor connected to the connecting element is a pressure sensor, which comprises an inlet in communicative connection with the inner chamber of the metal pipe.
In a fuel cell system the pipe assembly may be used on the cathode side, it mainly being applied, however, in an anode circuit.
A preferred embodiment of the invention is described below with reference to the drawing, in which Fig. 1 shows a section through a pipe assembly according to one embodiment of the invention.
A pipe assembly comprises a metal pipe 10. A pressure sensor 12 is intended to measure the pressure of a gas passing through the metal pipe 10. To this end, an opening 14 is provided in a portion of the metal pipe 10 in which the section shown in Fig. 1 is taken, via which opening gas from the inner chamber of the metal pipe 10 may enter the inner chamber 16 of the pressure sensor 12, where the actual measuring means of the sensor 12 is accommodated (which is not shown in Fig. 1).
The pressure sensor 12 comprises a base 18 of metal and a top 20 of plastics, between which the inner chamber 16 is formed. On the base 18 there is formed a thread, by
means of which the pressure sensor 12 may be screwed into a connecting element 22 (a "sensor port"), which is in turn connected to the metal pipe 10. The connecting element 22 may be heated by a heater 24. If condensation has collected in an opening 26 in the base 18 of the pressure sensor 12 and has frozen into ice, the heater 24 may bring about melting of this ice, so that the inner chamber 16 of the pressure sensor 12 is brought back into communicative connection with the inner chamber of the metal pipe 10. The rest of the pressure sensor 12 is also heated by the heater 24. This makes it possible to start up the pressure sensor 12 even under cold weather conditions. In particular when using the pipe assembly in a fuel cell system, a pressure sensor 12 has to supply reliable measured values immediately even in the case of a cold start.
The metal pipe 10 is here intended to consist of aluminum. So that the heat produced by the heating unit 24 does not flow away via the metal pipe 10, but rather heats up the pressure sensor 12, a plastics plate 28 is arranged between the connecting element 22 and the metal pipe 10 which consists for example of Teflon or polyphenylene sulfide and is sealed by means of O-rings 30, 30' relative to the connecting element 22 or the metal pipe 10. Fig. 1 does not show any fastening means, but it goes without saying that the connecting element 22 has to be fastened to the metal pipe 10 together with the plastics plate 28 by suitable connecting elements, for example suitable studs may be used outside the section shown.
List of reference signs
10 Metal pipe
12 Pressure sensor
14,26 Openings
16 Inner chamber
18 Base
20 Top
22 Connecting element
24 Heater
28 Plastics plate
30,30' O-rings