Design and Experimental Realization of a Steam-Driven Micro Recirculation Fan for Solid Oxide Fuel Cell Systems

The Laboratory for Applied Mechanical Design (LAMD) designed, manufactured, and experimentally tested a novel steam-driven anode off-gas recirculation (AOR) fan for 10 kWel solid oxide fuel cell (SOFC) systems. Due to the dynamic steam-lubricated bearings, the AOR unit is expected to have a high lifetime, even at elevated rotational speeds and temperatures. Additional, the unit is oil-free, explosion-proof, very compact, and cheap to manufacture. The AOR fan diameter is at 19.2 mm and the nominal rotational speed is 175 krpm. The unit was coupled to a 6 kWel SOFC system, reaching electrical gross DC efficiencies, based on the fuel LHV, of 66 % in part load (4.5 kWel gross DC) and 61 % in full load (6.3 kWel) for a global fuel utilization of 85 %. To the best of the authors’ knowledge, this was the first time that a steam-driven AOR fan was demonstrated in-situ with an SOFC system.