Criteria for Characterizing the Performances of Fuel Cell Humidifiers: Theoretical Approach and Experimental Results

In a proton exchange membrane fuel cell (PEMFC), humidification of reactant gases must be carefully optimized. Extremes in humidity levels at the low end (membrane dehydratation) and at the high end of the range (cathode flooding) can seriously reduce PEMFC performances. Various devices already exist to humidify and to adjust the temperature of gas streams. Criteria for the evaluation of their performances depend on the technology and/or differ from one manufacturer to the other, which makes comparison difficult. A fortiori, there is no consensus regarding their ideal values and no general method for their evaluation. The purpose of this article is to define two parameters (efficiencies) suitable for all humidification technologies and characterizing air humidifier performances in term of mass and heat transfer. These parameters allow to compare the different technologies and to define, for all of them, the range of performances required to supply fuel cells with properly humidified gases.