|
Race for the DWV innovation award decided
Theses on porous materials for hydrogen storage and flow fields in fuel cells selected
The winners in the DWV contest on the best diploma / master or doctor thesis from 2006 on hydrogen or fuel cells are now known. They are Mrs. Barbara Panella from Stuttgart (doctor thesis) and Mr. Heiko Holz from Erbach / Danube (diploma thesis).
Hydrogen storage capacity of porous materials
Barbara Panella, born 1978 in Rome, made her thesis on „Hydrogen Storage by Physisorption on Porous Materials“ at the University of Stuttgart and at the Max Planck Institute for Metals Research in the same city. She addresses the probably most important scientific problem of hydrogen technology, namely how to store large amounts of the gas in a small volume for long time with little energy input.
Apart from compressed gas and cryogenic liquid another way to do it is the physical adsorption (physisorption) of the molecules at the surface of highly porous materials. Of these we know many different kinds, from the classical activated carbon to carbon nanostructures. A few years ago sensational figures about the storage capacity of the latter were communicated, but could not be verified. Neither are the figures about the other materials very consistent. So the thesis is mainly about the systematic investigation of sorption mechanisms for different classes of materials, mainly either on carbon base or metal organic frameworks. This is a type of material discovered rather recently which has almost never been investigated under this aspect.
The maximum storage capacity of all investigated substances does not depend on their structure, but is proportional to their specific surface. This result will significantly facilitate future estimates of the performance of adsorber materials. The best carbon material was highly porous activated carbon with a storage capacity of 4.5 % (all % figures weight related) at 77 K. The value at ambient temperature was less than 0.5 %. The best adsorber at all was found to be a zinc based metal organic framework with 5.1 % at 77 K. The values at 200 K and ambient temperature were 1.2 % and less than 0.4 %, respectively.
The results indicate pathways to new methods to characterise porous materials and to develop or optimize new ones in order to obtain technically interesting storage densities.
Optimum transport of gases and liquids in the fuel cell
Heiko Holz, born 1980 in Ulm, has a professional background as car electrician and made his thesis on „Optimization of fuel cell components with respect to improved water removal under condensing operational conditions“ at the University for Applied Sciences in Ulm and at the ZSW institute in the same city. A fuel cell can work well only if the reaction area is always supplied with gaseous reaction partners, and at the same time the product water must be removed quickly enough. These two demands are basically contradictory, because wider gas channels for a lower pressure drop in the gas flow make it more difficult to get rid of the water.
Comprehensive test programs with different meander flow fields led to a shape with 23 parallel channels which was found to be a significant improvement under different boundary conditions; additionally it can be produced economically by stamping. In addition to the experimental work the results were also discussed under theoretical aspects so that further development steps based on the thesis are possible.
The formal presentation of the award will be held in the afternoon of June 6, 2007 during a public event on occasion of the annual DWV members' meeting in Munich at the TUV Sued.
Note for editors: pictures of the winners are available on request. If you want to participate in the event please contact us for the details of the program.
Published by the German Hydrogen and Fuel Cell Association (DWV), Berlin
Editor: Dr. Ulrich Schmidtchen, Berlin
|
