Dynamic Response of a Solid Oxide Fuel Cell Stack to Changes in a University Building’s Load

Abstract

The load-following performance of a solid oxide fuel cell (SOFC) stack is investigated for meeting the power demand of a university building. A numerical model is developed based on charge, species mass, energy, and momentum balances, and an equivalent circuit is used to combine the fuel cell’s irreversibilities. The fuel cell stack is sized to meet the peak electric load of a building located on the University of Pittsburgh’s campus. The SOFC model is verified on electrochemical, mass, and thermal timescales. Results indicate that higher inlet gas pressures improve load-following by generating power closer to demand after settling has occurred, but higher pressures do not guarantee a desired power level. It is also found that lower fuel utilizations correspond to faster settling times on the mass flow timescale but with the disadvantage of lower efficiency. Lastly, it is shown that the thermal settling time decreases as the excess air ratio increases, with a slight increase in the air’s exhaust temperature.