FUEL CELL DEVICE

Abstract

Fuel cell device for propulsion of a motor vehicle, and a method for operating the same. The fuel cell and a cryogenic tank storing liquid hydrogen, a boil-off management system keeping the pressure in the cryogenic tank below a threshold, the boil-off management system includes a boil-off conduit fluidically connected to the cryogenic tank via a boil-off valve. A mixing chamber is configured to mix a first medium flowing through the boil-off conduit with a second medium flowing in through the air feed conduit. A catalytic converter is connected downstream of the mixing chamber, and an outlet is connected downstream of the catalytic converter. A fuel cell off-gas tract, such that after anode purge operation of the fuel cell, off-gas is discharged through the fuel cell off-gas tract, which is configured such that medium flowing through the fuel cell off-gas tract can be conducted selectively and/or partially into the air feed conduit of the boil-off management system.

Claims

1. A fuel cell device for the propulsion of a motor vehicle, the fuel cell device comprising: a fuel cell; a cryogenic tank for storing supercooled gaseous hydrogen and/or liquid hydrogen; a boil-off management system to maintain the pressure in the cryogenic tank below a threshold value, the boil-off management system including: a boil-off conduit having a via a boil-off valve fluidically connected to the cryogenic tank, and through which is received a first medium, an air feed conduit through which is received a second medium, a mixing chamber for mixing the first medium with the second medium, a catalytic converter connected downstream of the mixing chamber, and an outlet connected downstream of the catalytic converter; a fuel cell off-gas tract configured such that after an anode purge operation of the fuel cell, off-gas is discharged therethrough, the fuel cell off-gas tract being further configured such that medium flowing therethrough is conducted at least selectively and/or partially into the air feed conduit.

2. The fuel cell device of claim 1, wherein the air feed conduit includes an air inlet funnel.

3. The fuel cell device of claim 2, wherein the fuel cell off-gas tract is configured such that medium flowing therethrough is conducted at least selectively and/or partially to the air inlet funnel.

4. The fuel cell device of claim 2, wherein the air inlet funnel is configured such that air or oxygen flows therethrough.

5. The fuel cell device of claim 1, further comprising a three-way valve configured to selectively fluidically connect the fuel cell off-gas tract to the air feed conduit and to a fuel cell off-gas tract outlet.

6. The fuel cell device of claim 1, wherein the fuel cell device is configured to mix an anode off-gas mass flow, which is discharged through the fuel cell off-gas tract after an anode purge operation of the fuel cell, with air and/or with a cathode off-gas mass flow.

7. The fuel cell device of claim 1, wherein the fuel cell device is configured such that an anode off-gas mass flow that is discharged through the fuel cell off-gas tract after an anode purge operation of the fuel cell is mixed to with air and/or with a cathode off-gas mass flow when said anode off-gas mass flow is conducted into the air feed conduit.

8. The fuel cell device of claim 1, further comprising a compressor for mixing the anode off-gas mass flow that is discharged through the fuel cell off-gas tract after an anode purge operation of the fuel cell with air and/or with a cathode off-gas mass flow.

9. The fuel cell device of claim 8, wherein the compressor is operated to a lesser degree, when the anode off-gas mass flow is conducted into the air feed conduit of the boil-off management system.

10. A method for operating a fuel cell device of claim 1, the method comprising: discharging, after an anode purge operation of the fuel cell, off-gas through the fuel cell off-gas tract; and selectively and/or partially conducting the medium flowing through the fuel cell off-gas tract at least into the air feed conduit.

11. The method of claim 10, wherein the medium flowing through the fuel cell off-gas tract at least into the air feed conduit is selectively and/or partially conducted at regular time intervals.

12. The method of claim 10, further comprising, after an anode purge operation of the fuel cell, mixing an anode off-gas mass flow that is discharged through the fuel cell off-gas tract with air and/or with a cathode off-gas mass flow when said anode off-gas mass flow is conducted into the air feed conduit.

13. The method of claim 10, further comprising, after an anode purge operation of the fuel cell, operating a compressor is operated to a lesser degree, when the anode off-gas mass flow is conducted into the air feed conduit.

Description

DRAWINGS

[0029] The disclosure will be described by way of example below with reference to the drawing. Like reference symbols in the various drawings may indicate like elements.

[0030] FIG. 1 shows a schematic view of a fuel cell device according to the disclosure.

DESCRIPTION

[0031] FIG. 1 illustrates a fuel cell device according to the disclosure that comprises a fuel cell, or a fuel cell system 1, and a cryogenic tank 2 for storing liquid hydrogen.

[0032] The cryogenic tank 2 comprises a boil-off management system 3 in order to keep the pressure in the cryogenic tank 2 below a threshold value, wherein the boil-off management system 3 comprises a boil-off conduit 4, which is fluidically connected to the cryogenic tank 2 and which has a boil-off valve 5, and comprises an air feed conduit 6, and a mixing chamber 7 for mixing the medium flowing in through the boil-off conduit 4 with the medium flowing in through the air feed conduit 6. The boil-off management system 3 furthermore comprises a catalytic converter 8 connected downstream of the mixing chamber 7, and an outlet 9 connected downstream of the catalytic converter 8.

[0033] The fuel cell or the fuel cell system 1 can, for example, be purged at regular intervals, wherein an anode off-gas mass flow 14, mixed with a cathode off-gas mass flow 15 and/or with air, is then conducted through a fuel cell off-gas tract 10 to a fuel cell off-gas tract outlet 13, and for example released into the surroundings at the fuel cell off-gas tract outlet 13.

[0034] The anode off-gas mass flow 14 may be formed by a fuel cell anode off-gas that has a high hydrogen content. The cathode off-gas mass flow 15 may be provided by a compressor and may contain oxygen. Hydrogen, atmospheric gases and/or water vapour, among others, may be present in the fuel cell off-gas tract 10.

[0035] The fuel cell off-gas tract 10 is configured such that medium flowing through the fuel cell off-gas tract 10 can be conducted selectively into the air feed conduit 6 of the boil-off management system 3, more specifically into an air inlet 11, in particular, air inlet funnel, of the air feed conduit 6 of the boil-off management system 3. The fuel cell off-gas tract 10 is selectively connectable by means of a three-way valve 12 to the air feed conduit 6 of the boil-off management system 3 and to the fuel cell off-gas tract outlet 13.

[0036] In addition to the medium flowing through the fuel cell off-gas tract 10, fresh air or oxygen can also pass through the same air inlet 11 at the air feed conduit 6 of the boil-off management system 3. An air filter 16 is optionally arranged in the air feed conduit 6.

[0037] The anode off-gas mass flow 14 that is discharged through the fuel cell off-gas tract 10 after an anode purge operation of the fuel cell or of the fuel cell system 1 can be mixed to a lesser degree, or not mixed at all, with air and/or with the cathode off-gas mass flow 15 if said anode off-gas mass flow is conducted into the air feed conduit 6 of the boil-off management system 3 than if said anode off-gas mass flow is conducted to a fuel cell off-gas tract outlet 13, because the hydrogen of the anode off-gas mass flow 14 is reacted in the catalytic converter 8 of the boil-off management system 3.

TABLE-US-00001 LIST OF REFERENCE SYMBOLS 1 Fuel cell 2 Cryogenic tank 3 Boil-off management system 4 Boil-off conduit 5 Boil-off valve 6 Air feed conduit 7 Mixing chamber 8 Catalytic converter 9 Outlet 10 Fuel cell off-gas tract 11 Air inlet 12 Three-way valve 13 Fuel cell off-gas tract outlet 14 Anode off-gas mass flow 15 Cathode off-gas mass flow 16 Air filter