Design and development of a 7kW PEMFC stack for UPS application

UPS and back-up power system market is the most affordable for Hydrogen PEM technology. To promote technology transfer and, at the same time, meet UPS technical requirements, a 7 kW PEMFC stack was designed manufactured and tested. A liquid cooled stack was designed for operating at 70°C, room pressure with low humidified gases. A single cell active area of about 200cm2 was used to obtain a total current of 172A at 0.6V with a 1.2 - 2 stoichiometric ratio for hydrogen and air respectively. Gore Primea 5621 MEA was selected. Anodic and cathodic flow fields were optimized to operate at a low pressure drop for reducing parasitic losses. A proprietary design methodology has permitted the single cell performance to be directly scaled up to the 70 cells unit, avoiding intermediate test phases on a sub-stack to be conducted. Single cell tests on three different cathodic flow fields were carried out to improve the design methodology efficiency and a compromise in terms of durability and performance. Preliminary tests of the full unit, conducted with hydrogen recirculation, yielded to a 6.2kW output at 36V. In this work the design procedure, single cell test and preliminary results are reported.