Fuel cell device with catalyst

Abstract

The invention relates to a fuel cell device (10) comprising a housing (12) with a housing wall (14) delimiting a cavity (16), a fuel cell stack (18) arranged within the cavity (16), wherein catalysts (22) for recombination of volatile fuel gas present in the cavity (16) with atmospheric oxygen into an inert liquid recombination product (26) are arranged in the cavity (16) outside the fuel cell stack (18).

Description

The invention relates to a fuel cell device according to the preamble of claim 1.EP 1 624 516 A1 describes a fuel cell device having a housing and a fuel cell stack arranged within the housing. In order to keep the interior of the housing free of an explosive fuel mixture, the leaked fuel is discharged from the interior by introducing air into the interior, which flows through the interior and is then introduced to the cathodes of the fuel cell stack to be decomposed there by reaction with atmospheric oxygen.The object of the present invention is to provide a fuel cell device with improved explosion protection. Explosion protection is to be implemented cost-effectively and reliably. The fuel cell device should be designed to save space and at low cost.At least one of these objects is achieved by a fuel cell device having the features according to claim 1. As a result, the volatile fuel gas, for example hydrogen, can be degraded in the cavity and the fuel cell device can be designed to be explosion-proof.The fuel cell device may be a polymer electrolyte fuel cell. The fuel cell device can generate mainly electric power by electrochemical reaction of the fuel gas and atmospheric oxygen.The housing may include a housing wall. The housing wall can be constructed in several parts.The fuel cell stack can also be referred to as a fuel cell stack. The fuel cell stack may include a plurality of fuel cells electrically connected to each other and having at least one anode and cathode.The fuel cell apparatus may include piping means for supplying the fuel cell stack with the fuel gas and air. The fuel cell device may include a cooling device for cooling the fuel cell stack. The cooling device may be at least partially disposed within the housing.The volatile fuel gas may leak into the cavity through leaks and / or diffusion within the housing. The volatile combustion gas preferably has a lower density than air.The recombination product may be water. Recombination to the catalyst may be an exothermic reaction. The temperatures formed during the recombination can be less than the ignition temperature of the fuel gas, in particular less than 500 degrees Celcius.The cavity may be an interior volume defined by the housing wall of the housing. The cavity can be filled with a filling gas, in particular air. The cavity can have an internal pressure corresponding to the ambient pressure with respect to the environment of the housing by pressure compensation.The fuel gas can be hydrogen or a gas, in particular mainly, containing hydrogen.The atmospheric oxygen for recombination to the catalyst may originate from the air in the cavity. The atmospheric oxygen for recombination at the catalyzing agent can be directed to the catalyzing agents.The catalysts can be constructed from a noble metal, in particular platinum, palladium, ruthenium, rhodium, a transition metal, in particular nickel, cobalt and / or an alloy, in particular a platinum-palladium alloy or a nickel-cobalt alloy. The catalysts may comprise a support material, in particular a nonmetal, for example a ceramic, preferably aluminum oxide or silicon dioxide.The catalysts can be arranged on the housing wall. The energy formed during the recombination by the catalysts can be present mainly, in particular exclusively, as thermal energy. The catalysts can be coolable via the housing wall. Furthermore, a cooling device for dissipating the thermal energy generated can be arranged on the catalysis means.In a preferred embodiment of the invention, it is advantageous if the catalysis means are arranged at the uppermost position in the cavity with respect to the direction of gravity. Thereby, accumulation of the fuel gas in the cavity can be prevented by bypassing the recombination to the catalyst.A preferred embodiment of the invention is advantageous in which the catalysis means are arranged at least partially overlapping with respect to the direction of gravity with respect to the fuel cell stack. The catalysts can also be arranged above the fuel cell stack with respect to the direction of gravity.In a preferred embodiment of the invention, it is provided that the catalysis means are arranged offset to the fuel cell stack with respect to a direction perpendicular to the direction of gravity. This makes it possible to prevent the fuel cell stack from being wetted with the recombination product.In a preferred embodiment of the invention, it is provided that the catalysis means span an area of at least 1 mm 2 per kW of electrical power of the fuel cell stack. As a result, the recombination of the volatile combustion gas in the cavity can take place efficiently, in a space-saving and cost-effective manner.In a preferred embodiment of the invention, it is provided that the catalysis means comprise at least one catalysis element and the largest dimension of the catalysis element in the three spatial directions is at least one dimension of the surface region. The catalysts can be rectangular, circular, oval or round.A preferred embodiment of the invention is advantageous in which the housing wall has an outlet opening connected to the cavity for discharging the recombination product. A discharge line can close off from the housing on the surrounding side to the outlet opening. The recombination product can reach the outlet opening without guidance starting from the catalysts. Also, conduit means may be arranged for guiding the recombination product from the catalysis means to the outlet opening within the cavity. The conduit means may comprise at least one conduit, a channel and / or a baffle plate. The recombination product can pass mainly, in particular exclusively, from the catalysts to the outlet opening as a result of the influence of gravity.A preferred embodiment of the invention is advantageous in which the outlet opening is a condensed water opening for further discharge of condensed water from the cavity. The outlet opening may be arranged at a lowermost position of the cavity with respect to the direction of gravity.In a preferred embodiment of the invention, it is provided that the outlet opening is closed by a water-permeable membrane. Thereby, a gas pressure inside the cavity can be maintained. Gas exchange via the outlet opening can be prevented. The membrane may be a hydrophilic membrane.In a preferred embodiment of the invention, it is provided that the catalysis means are configured as a whole spatially contiguous. The catalysts may consist of a single catalyst element. The catalysis means can also comprise a plurality of spatially distributed individual catalysis elements which are separate from one another.Further advantages and advantageous embodiments of the invention result from the description of the figures and the figures.DESCRIPTION OF THE FIGURESThe invention will be described in detail below with reference to the drawings. They show in detail: FIG. 1 is a cross-sectional view of a fuel cell device in a specific embodiment of the invention. FIG. 2 : a detail of a cross section of a fuel cell device in a further specific embodiment of the invention.FIG. 1 shows a cross section of a fuel cell device in a specific embodiment of the invention. The fuel cell device 10 comprises a housing 12 which, together with a housing wall 14, delimits a cavity 16 in which a fuel cell stack 18 for generating electrical energy from the recombination of a fuel gas, in particular hydrogen with atmospheric oxygen, is arranged. Within the cavity 16, a cooling device 20 for cooling the fuel cell stack 18 is arranged in particular. Furthermore, the housing 12 has a connection device, which is not visible here, for introducing the fuel gas and atmospheric oxygen from a surrounding area of the housing 12 to the fuel cell stack 18.Leaks or diffusion allow fuel gas to escape into the cavity 16 and form an explosive mixture with the air present there, which leads to a risk of explosion for the fuel cell device 10.In the cavity 16 outside the fuel cell stack 18, catalysis means 22 for recombination of volatile fuel gas 24 present in the cavity 16 with atmospheric oxygen into an inert liquid recombination product 26, here in particular water, are arranged. Thereby, the accumulation of an explosive mixture in the cavity 16 can be prevented, and explosion protection for the fuel cell device 10 can be realized.The catalysts 22 are arranged at the uppermost position 30 in the cavity 16 with respect to the direction of gravity 28. Furthermore, the catalysis means 22 are arranged at least partially overlapping with respect to the direction of gravity 28 with respect to the fuel cell stack 18 and offset with respect to the fuel cell stack 18 with respect to a direction 32 perpendicular to the direction of gravity 28.The catalysis means 22 comprise a plurality of spatially distributed individual catalysis elements 34 which are separated from one another and have a total surface area 36 of at least 1 mm 2 per kW of electrical power of the fuel cell stack 18.The housing 12 has an outlet opening 40 connected to the cavity 16 for discharging the recombination product 26. The outlet opening 40 is, for example, furthermore a condensed water opening 42 for further discharge of condensed water from the cavity 16.FIG. 2 shows a detail of a cross section of a fuel cell device in a further specific embodiment of the invention. The structure of the fuel cell device 10 is similar to that of FIG. 1 except for the following differences. The outlet opening 40 in the housing wall 14 is closed by a water-permeable membrane 44. The membrane 44 is preferably a hydrophilic membrane 44.List of reference characters10 Fuel cell device 12 Housing 14 Housing wall 16 Cavity 18 Fuel cell stack 20 Cooling device 22 Catalytic agent 24 Volatile fuel gas 26 Recombination product 28 Gravity direction 30 Uppermost position 32 Direction 34 Catalytic element 36 Surface region 38 Dimension 40 Outlet opening 42 Condensed water opening 44 MembraneReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 1 624 516 A1

[0002]

Claims

Fuel cell device (10) having a housing (12) with a housing wall (14) delimiting a cavity (16), a fuel cell stack (18) arranged within the cavity (16), characterized in that catalysis means (22) for recombination of volatile fuel gas present in the cavity (16) with air oxygen into an inert liquid recombination product (26) are arranged in the cavity (16) outside the fuel cell stack (18).Fuel cell device (10) according to claim 1, characterized in that the catalysis means (22) are arranged at the uppermost position (30) in the cavity (16) with respect to the direction of gravity (28).Fuel cell device (10) according to Claim 1 or 2, characterized in that the catalysis means (22) are arranged at least partially overlapping with respect to the direction of gravity (28) with respect to the fuel cell stack (18).Fuel cell device (10) according to one of the preceding claims, characterized in that the catalysis means (22) are arranged offset with respect to the fuel cell stack (18) with respect to a direction (32) perpendicular to the direction of gravity (28).Fuel cell device (10) according to one of the preceding claims, characterized in that the catalysis means (22) span a surface region (36) of at least 1 mm 2 per kW of electrical power of the fuel cell stack (18).Fuel cell device (10) according to Claim 5, characterized in that the catalysis means (22) comprise at least one catalysis element (34), and the largest dimension (38) of the catalysis element (34) in the three spatial directions is at least one dimension of the surface region (36).Fuel cell device (10) according to one of the preceding claims, characterized in that the housing wall (14) has an outlet opening (40), which is connected to the cavity (16), for discharging the recombination product (26).Fuel cell device (10) according to Claim 7, characterized in that the outlet opening (40) is a condensed water opening (42) for further discharging condensed water from the cavity (16).Fuel cell device (10) according to Claim 7 or 8, characterized in that the outlet opening (40) is closed by a water-permeable membrane (44).Fuel cell device (10) according to one of the preceding claims, characterized in that the catalysis means (22) are configured to be spatially contiguous overall.

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