Initial startup of a direct-fired fuel cell turbine power system with equivalence ratio control using cathode air bypass valves to minimize thermal shock to the fuel cell was evaluated using the Hybrid Performance (Hyper) project hardware-based simulation facility at the U.S. Department of Energy, National Energy Technology Laboratory. The turbine in the system was started with the minimum possible airflow through the fuel cell cathode from a cold condition using two bypass valves to mitigate thermal shock failure in the fuel cell. The limitation of bypass flow was set by air requirements to maintain a combustor equivalence ratio below 0.7 during turbine windup. A 1D distributed fuel cell model operating in real time was used to produce individual cell transient temperature profiles during the course of the turbine start. The results provide insight into the procedural requirements of starting a fully coupled hybrid system.
