Characterizing Performance of a PEM Fuel Cell for a CMET Balloon

We present the design of a multi-cell, low temperature PEM fuel cell for controlled meteorological balloons. Critical system design parameters that distinguish this application are the lack of reactant humidification and cooling due to the low power production, high required power mass-density and relatively short flight durations. The cell is supplied with a pressure regulated and dead ended anode, and flow controlled cathode at variable air stoichiometry. The cell is not heated and allowed to operate with unregulated temperature. Our prototype cell was capable of achieving power densities of 43 mW/cm²/cell or 5.4 mW/g. The cell polarization performance of large format PEM fuel cell stacks is an order of magnitude greater than for miniature PEM fuel cells. These performance discrepancies are a result of cell design, system architecture, and reactant and thermal management, indicating that there are significant gains to be made in these domains. We then present design modifications intended to enable the miniature PEM fuel cell to achieve power densities of 13 mW/g, indicating that additional performance gains must be made with improvements in operating conditions targeting achievable power densities of standard PEM fuel cells.