Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Patent
1998-07-23
2000-06-27
Kalafut, Stephen
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
429 38, 429 39, 429 26, 429120, 204242, H01M 200
Patent
active
060805021
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a fluid-cooled fuel cell, in which the cell surfaces are supplied with reaction media via axial supply ducts and radial distribution ducts.
Patent application 44 42285.7 (94 P 3704), which has not yet been published, describes a battery that comprises fuel cells and in which the cell surfaces are also supplied via axial supply ducts and radial distribution ducts. However, this design is primarily suitable for fuel cells which are cooled via direct air cooling, since neither distribution ducts nor supply ducts for coolant are provided. Batteries comprising fuel cells have to be cooled more intensively as the power density per unit area of the battery increases. In many cases, pure air cooling is not sufficient, because of its limited heat transfer. Fluid cooling would therefore be necessary, but in the case of fuel cells of this type it is possible only by replacing the cooling medium air with a fluid, which is guided in an external vessel which encloses the entire battery. The problem here is, on the one hand, that the fluid may come into direct contact with the electrolyte (which leads to creepage currents and to corrosion) and, on the other hand, that the container takes up space. Practical fluid cooling is therefore not yet available for this design.
Although DE 42 34 093 discloses the corrosion-free cooling of cell surfaces of a fuel cell using a liquid, it does not disclose any design which ensures uniform inflow to the surfaces which are to be cooled and those which are active. Instead, in this prior art, the result of a point-like inlet is a diagonal flow of the media over the cell surfaces, which is accompanied by an undersupply to those marginal regions of the cell surface that are adjacent neither to an inlet opening nor to an outlet opening. As a result, the performance of the fuel cell is reduced by comparison with a uniform supply to the surfaces. Furthermore, the constructional elements that are disclosed in that document require high production costs, since the individual supply and distribution ducts have to be terminated in a gastight manner by means of one or more collecting lines. Both the high production costs and the partial undersupply to the cell surface have a detrimental effect on the attractiveness of the fuel cell as one of the energy converters of the future.
SUMMARY OF THE INVENTION
It is therefore an advantage of the present invention to provide a compact fuel cell which is capable of mass production, has fluid cooling and whose simple design enables uniform inflow to the cell surfaces, without increasing the cell thickness.
The general discovery of the present invention is that distribution ducts in the edge region of the cell surfaces can be fitted, by means of stacking and staggering, in such a way that as a rule) of media, plurality of connecting lines which, according to the prior art, are welded joints, and axially in relation to the cell surface) in the case of fluid-cooled batteries results from possibly dispensing with two intermediate elements between the individual cells of a fuel-cell block, and from eliminating the axial space requirement of the fluid cooling.
The subject of the invention is a fuel cell with fluid cooling, which comprises a cathode, an electrolyte and an anode, at least one distribution duct for supplying the cell surface with medium being provided and being fitted in the cell surface in such a way that the cell surface is supplied with medium from this distribution duct and along the edge of the cell surface.
A fuel cell and/or a fuel-stack according to the invention can be operated by self-induction, that is to say using only one axial supply duct for supplying the anode with fuel and a further supply duct for supplying the cooling surfaces, but without a supply duct to the cathode. The same applies to the discharge ducts.
One embodiment of the invention contains the distribution ducts in a radial (perpendicular) position in relation to the axial supply ducts, but the invention is not rest
REFERENCES:
patent: 3575719 (1971-04-01), Nelson et al.
patent: 4678724 (1987-07-01), McElroy
patent: 5514487 (1997-06-01), Washington et al.
patent: 5635039 (1997-06-01), Cisar et al.
Publication entitled: "Effiziente Nutzung fossiler Energietrager mit Brennstoffzellen" by Christoph Nolscher.
Mattejat Arno
Nolscher Christoph
Alejandro R
Kalafut Stephen
Siemens Aktengesellschaft
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