Gases permeability study in dual membrane fuel cell
Résumé
Gases permeability in a porous mixed (proton and oxide ion) conductive membrane, which is a component of a new high temperature dual membrane fuel cell design is investigated by specially designed testing system based on measurements of the gas flow [ml/min] and pressure P (mm H2O) when penetrating through porous media. A strong correlation expressed in increase of the permeability with the decrease of the gases molecular weight is registered. The water vapor permeability decreases with the temperature. This is in agreement with data from the literature which show that the viscosity of gases, including water vapor, increases with the temperature. The results obtained suggest optimal porosity in respect to permeability, mechanical stability and conductivity in the range of 35-40%. They confirm the need of optimization concerning not only the pores fraction, but also the pores geometry and distribution, as well as the central membrane geometry and the configuration of the cell. This approach can be applied also for optimization of the electrodes porosity (pores concentration, geometry, distribution etc), especially in cases when gas mixtures (including water vapor) are used or produced.