Electrochemical Hydrogen Recirculation Device suited for PEM Fuel Cell
Résumé
In current PEM fuel cells, high purity hydrogen is used as a fuel. This allows both to have good performances and to prevent the accumulation of inert gaz in the fuel cell when recirculation devices are used. This high purity gas involves considerable costs. It is possible to operate a PEMFC stack with non- pure anodic gases. This generates a loss of performances. The impure gases cannot be used in a fuel cell system using a hydrogen recirculation loop as impurities will tend to accumulate in the loop. Such gases must be used in configuration of continuous leakage to prevent any accumulation. We propose a solution to deal with non pure hydrogen. This solution uses an electrochemical hydrogen pump[1] that pumps solely pure hydrogen and thus removes a significant portion of impurities from the anodic gases. This solution is illustrated in the next figure. Polluted hydrogen enters the anodic compartment where it is consumed. The pump then separates the hydrogen from the pollutant. The pollutant is discharged through the leak and hydrogen is recirculated to the anodic compartment. A first experiment has shown the ability of such a device to pump hydrogen from mixtures (H2 -N2, H2-CH4, CO2-H2). A second experiment has shown that this pump can be used in place of a mechanical pump in a recirculation loop and that it permits to achieve the same performance of the stack. Finally, an experiment is underway to test the ability of the recirculation loop to deal with a polluted gaz. Reference : 1. F. Barbir et H. Görgün, « Electrochemical hydrogen pump for recirculation of hydrogen in a fuel cell stack », J. Appl. Electrochem., vol. 37, no 3, p. 359‑365, mars 2007.