Rudolf Metkemeijer

Ammonia as a feedstock for a hydrogen fuel cell; reformer and fuel cell behaviour

In this paper, an indirect ammonia fuel cell system is proposed which circumvents the problem of hydrogen storage. System analysis shows that the specific energy density (kWh/kg or kWh/m3) of such a system is very attractive compared with that of a direct hydrogen fuel cell system. The fuel cell stocks have an important impact on these figures. However, both the indirect ammonia and the direct hydrogen systems use the same type of fuel cells, and improvement in fuel cell characteristics will improve the specific power and energy densities of both systems. Earlier work also showed that ammonia is a more attractive fuel than methanol for an indirect fuel cell. Ammonia therefore merits more attention as a fuel cell feedstock.

Impact of the water symmetry factor on humidification and cooling strategies for PEM fuel cell stacks

In this paper, experimental water and thermal balances with three proton exchange membrane fuel cells (PEMFC) are proposed. On the test facility of Ecole des Mines de Paris, three De Nora SPA fuel cell stacks have been successfully studied: An 1 kWe prototype using Nafion® 117, a 5 and a 10 kWe module using Nafion® 115. The averaged water symmetry factor determines strategies to avoid drying membrane. So, we propose analytical solutions to find compromises between humidification and cooling conditions, which determines outlet temperatures of gases. For transport applications, the space occupied by the power module must be reduced. One of the main efforts consists in decreasing the operative pressure. Thus, if adequate cooling power is applied, we show experimentally and theoretically the possibility to use De Nora PEM fuel cells with low pressure, without specific external humidification.