Performance Evaluation of a Thermally Integrated Fuel Cell System in the Presence of Uncertainties

In this work, we focus on robustness analysis of an integrated fuel cell and fuel reforming (FCFR) system, which relies on a feedback controller to mitigate hydrogen starvation and temperature overshoot during load transitions. The fuel reformer is used to process natural gas into a hydrogen rich flow to be utilized in a proton exchange membrane fuel cell (PEM-FC). The feedback controller uses the catalytic burner (CB) and the catalytic partial oxidizer (CPOX) temperatures as measurements and adjusts the air and fuel actuator commands to assure fast load following and high steady state efficiency. Several uncertainty sources which can potentially lead to closed loop performance deterioration are considered, including CPOX clogging, hydro-desulphurizer (HDS) clogging, fuel uncertainty and CB parameter uncertainty. Steady state and transient performance are analyzed for the different uncertainty scenarios, for both open and closed loop operation (i.e., with and without feedback control). The robustness of load following and CPOX temperature regulation of the closed loop system (feedforward and feedback controlled) is established, while the open loop system (feedforward controlled) is shown to be vulnerable to all sources of uncertainties considered.