Forschungszentrum Julich Gmbh

Forschungszentrum Juelich Gmbh

Detlef Stolten

Hendrik Dohle

Jürgen Mergel

Zdenek Pors

Joachim Pasel

Ralf Peters

Helmut Baltruschat

Michael Weber

Thomas Bewer

Anderas Tschauder

Jan Bringmann

Martin Müller

Andreas Tschauder

Thorsten Wüster

Jan Stalling

Thomas Beckmann

Anne Bendzulla

Ayhan Egmen

Jörg Wilhelm

Rudolf Dahl

Remzi Can Samsun

Paul Cremer

Ludger Blum

Sebastian Schiebahn

Ernst Riensche

Jochen Latz

Johannes Werhahn

Li Zhao

Andreas Maintz

Holger Janssen

A process with which a liquid fuel is evaporated completely in two stages is provided. In the first stage, the fuel is mixed with a hot primary medium and partly evaporated. In the second stage, the already evaporated fuel fraction is partly oxidized, which provides the heat for the complete evaporation of the fuel fractions which are yet to be evaporated. A fuel-air mixture for a reformer can be obtained with an advantageous embodiment of the process, in which the fuel is mixed homogeneously with oxidizing agent in the inventive evaporation. For the performance of the process, a mixing chamber is provided.

Process for evaporating a liquid fuel and a mixing chamber for performing this process

In low-temperature fuel cells according to prior art, the problem often arises that the diffusion layer of the cathode is filled by water which is permeated or produced on the cathode, such that oxygen can no longer be transported to the catalyst layer of the cathode in a frictionless manner. As a result, said fuel cells are regularly used with a high excess of oxygen in order to reduce the cited transport problems for the oxygen. The inventive fuel cell enables said problem to be solved in that the arrangement of the diffusion layer and the catalyst layer of the cathode is inverted. The diffusion layer, which is embodied in such a way as to also conduct ions, is directly adjacent to the electrolyte membrane. The catalyst layer oriented towards the free cathode space can advantageously directly react with the supplied oxygen without further transport problems. A further advantage lies in the fact that the water produced on the catalyst layer of the cathode and/or permeated by the electrolyte membrane and the diffusion layer can be easily withdrawn via the free cathode space.

Cathode for a direct methanol fuel cell and method for operating the same

Liquid fuel is evaporated and mixed with an oxidizing agent in a mixing chamber of a reformer by first introducing substantially only the liquid fuel in an axial downstream direction into a first upstream zone of the mixing chamber via a nozzle so as to atomize the liquid fuel. Then steam is separately introduced into the upstream zone and contacted with the atomized fuel to cause the fuel to evaporate. An oxidizing agent is then introduced downstream of the first zone in a second zone of the mixing chamber to the evaporated fuel and uniformly mixing the oxidizing agent with the evaporated fuel.

Reformer mixing chamber and method for operating same

In a direct-methanol fuel cell stack with an at least partial circulation () of the fuel, according to the invention a means is arranged in this circulation for reducing the concentration of an undesired byproduct. This means is comprised especially of a further electrochemical cell () to which electric current is applied and which at least partly transforms the byproducts by an electrochemical reduction reaction again to methanol and water. Since the concentration of byproducts is small, the loss in electric current required for the additional reduction reaction has no noticeable effect on the efficiency of the fuel cell stack.

Fuel cell stack with circuit

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Aachen, Germany

Detlef Stolten