Comparison of different fuel cell temperature control systems in an anode and cathode ejector-based SOFC-GT hybrid system

Abstract

Solid oxide fuel cell-gas turbine (SOFC-GT) hybrid systems are facing challenges in terms of fuel cell temperature control due to its significant effect on safe and efficient operation. In this study, five different temperature control systems are designed according to different SOFC control strategies and control points in anode and cathode ejector-based SOFC-GT hybrid systems. Firstly, three SOFC temperature control strategies including only anode-side control, only cathode-side control, and two-side control are compared. The comparison results indicate that the cathode-side temperature control strategy can effectively maintain the system efficiency. In addition, the two-side control strategy is better than one-side control strategies considering the safe operation of the anode and cathode differential temperature. Then, three SOFC temperature control points including input temperature, output temperature, and average temperature are chosen in order to investigate the effect of control variables. The comparison results indicate that maintaining the average temperature is better than the other temperature control points. Therefore, the two-side average temperature control system of SOFC is more appropriate to guarantee efficient and safe operation. The temperature distribution in SOFC is more feasible, and the efficiency of SOFC and the whole hybrid system is most efficient at a part load condition.