Experimental Analysis of the Voltage and Temperature Behavior of a Solid Oxide Fuel Cell Generator

Abstract

A solid oxide fuel cell (SOFC) laboratory has been installed in Torino, Italy, in order to analyze the operation, in a cogenerative configuration, of the CHP-100 SOFC Field Unit built by Siemens Power Corporation (SPG) Stationary Fuel Cells (SFC), within the framework of the EOS Project. An experimental session was performed, varying the setpoint temperature TGEN and the fuel consumption (FC), with the aim of characterizing the behaviour of the local voltages and temperatures. A design of experiments procedure was applied to obtain first (simple 22) and second-order (spherical central composite design (CCD)) regression models, which were then used in subsequent constrained optimization procedures. A sensitivity analysis was also performed: FC revealed as the prevailing control factor of the operation, and it was shown that the analysis of the local voltage and temperature sensitivity to FC can be used as a diagnostic tool for the fuel distribution within a SOFC generator (the homogeneity of the sensitivity of the various cells was ∼10%, depending strongly on the cell bundle arrangement in the stack). Finally, the effect of any changes in the control factors on the tube temperature profile was evaluated and discussed; a link between a high terminal voltage and a more uniform temperature along the cell tube has been pointed out.