Study of SOFC-SOE transition on a RSOFC stack

Reversible Solid Oxide Fuel Cell (RSOFC) can perform both power production and electricity storage with high efficiency and reduced cost using the same device for both functions. Within the frame of a small scale application and distributed generation, RSOFC systems operate connected to the grid switching from electrolysis to fuel cell and vice versa depending on load and grid peculiarities. The study aims to investigate the behavior of RSOFC in the two operation modes and in the transition phase. The analysis moves from the thermal equilibrium and electrical performances data gathered during the test of a six cells SOFC short stack. In particular, the effect of gas composition was deeply investigated. A mapping of performances was realized through polarization curves. Dilution of reactants, both in SOFC and SOE brings to reduction in performances while different compositions during SOE-SOFC transition did not give any significant effect to stack voltages. The dynamic model was derived from experimental results; thermal and electrical transient response to current variation was determined under several operating conditions and related transfer functions were identified characterizing the device dynamic behavior.