This project is handled in cooperation with the following partners: Forschungszentrum Jülich, Federal Institut for Materials Research and Testing in Berlin, Technical University Berlin and Freudenberg FCCT. Mathematical models will be developed in order to quantitatively describe the microstructure of porous materials. These materials are used in the so-called gas diffusion layer (GDL) of fuel cells. So far, mainly paper-type GDL with straight lined fibers have been examined, (cf. Fig. 1-3), whereas now velt-type GDL will be analyzed which consist of clearly curved fibers (cf. Fig. 4-5). 

The fuel cell technology provides an efficient way to convert hydrogen into electricity. This allows the replacement of oil products as energy carrier, e. g. in automobiles or submarines.

A key component of a fuel cell is the GDL. On the one hand the GDL is responsible for the transport of hydrogen and oxygen to the electrodes where the electrochemical reaction takes place. On the other hand its task is the removement of the water produced. In this context it is important that just the right water content is achieved because water is essential for the conductivity of the membrane, whereas excess of water in the GDL leads to a flooding of the pores which in turn limits current density. Hence the balance between water drainage and water storage is the key for a high performance. Additionally the GDL acts as a conductor for the produced electricity.

In order to analyze the correlation between structural properties and transport processes of GDL a stochastic simulation model for the microstructure of GDLs with curved fibers under different degree of compression will be developed.

By means of these models the goal is to detect structures, which show optimal transport properties. This approach has an important potential to contribute to the product development and to the improvment of a trend-setting technology, respectively.

Applications: Virtual Material Design

• Development and fitting of a stochastic simulation model for the microstructure of GDLs with curved fibers
• Simulation of physical transport processes in simulated structures
• Quantification of the correlation between performance and microstructure
• Detection of improved microstructures via computer simulations

This research project is integrated in the research network"3D Analyse, Modellierung und Simulation der Mikrostruktur und Transportprozesse in faserbasierten porösen Materialien" in the context of the funding initiative "Mathematik für Innovationen in Industrie und Dienstleistungen"of the Federal Ministry of Education and Reasearch.

Contact persons: Prof. Schmidt