Hydrogen/Oxygen breadboard design and testing for space applications

This work presents the results of the breadboard design and testing research performed at CNR-ITAE for PEFC stack in space applications under contract with ESA and CGS S.p.A [1]. The target was to design three different breadboards with a two 500 W stacks fed with pure hydrogen and oxygen to test the performance and identify the major issues of PEFC technology operating under space conditions, specifically resembling a Lunar Base (LB) and a Pressurised Lunar Rover (PLR). Three different breadboards (BB) were designed and built at ITAE: a Basic BB, used for stack testing; a Stand-Alone BB, used to test the performance of the stacks integrated with all the auxiliaries in a stand-alone unit (compressors, cooling loop, supervision and control); a Closed-Loop BB, integrating an electrolyser for hydrogen production. The three breadboards underwent several tests including polarisation, time-test and orientation sensitivity (Basic BB), calculated load profiles resembling the day/night Moon cycle and failure test (stand-alone and closed-loop BBs) simulating a partial failure of the power system. A comparative test was performed to identify the critical failure modes of a fuel cell stack not designed for space conditions. The results show that, although the standard stack did not withstand the tests, the space-designed stack operated regularly without any performance, safety or reliability issues even in case of failure. Only the orientation test led to a failure in two of the tests, showing that this aspect, together with auxiliary design, are the most important issues to address in such application.