The Need of Uniform PEMFC Stack Test Procedures and their Validation

Kurzfassung

The test procedures for polymer electrolyte membrane fuel cells (PEMFCs) are of significant relevance to assure comparable results for industrial research and development as well as academic studies. Certainly, PEMFC test results from different testing facilities are hardly comparable due to the variation in the test procedure and/or the test equipment. These differences strongly influence the examination results in PEMFC single cells, but affect stack results even more. Several aspects have to be considered for a reproducible and comparable stack test. On the one hand the operating parameters like reactant humidity, pressure and stoichiometry as well as stack temperature and electric load have to be controlled in a correct and reproducible manner. On the other hand it is mandatory to ensure the accurate measurement of these test input parameters as well as the test output parameters, namely stack and single cell voltage. Consequently, the positioning of the different parameter sensors, the choice of the control parameters and the sequence of parameter adjustment have to be defined in harmonized test protocols. The preparation of such test protocols and their validation using a 10 cell PEMFC stack will be presented in detail. The present work will demonstrate the influence of the test protocols to the test results and the comparability of measurements in different testing facilities across Europe. In addition to the procedures regarding the already mentioned test input parameters, the optimization of polarization curve measurements and electrochemical methods will be demonstrated. Thereby, the interest was focused on the individual cells as well as the full PEMFC stack. The presented procedures as well as the validation results are part of the Stack-Test project funded by the European Union Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant n° 303445. We gratefully acknowledge the members of the Stack-Test consortium who prepared, improved and validated the test procedures.