화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.48, No.13, 6112-6125, 2009
Dynamics and Control of a Tubular Solid-Oxide Fuel Cell
This paper presents a study of the dynamic behavior and control of a tubular solid oxide fuel cell system. A dynamic compartmental model that is based on first principles is developed. The model accounts for diffusion processes, inherent impedance, transport (heat and mass transfer) processes, electrochemical processes, anode and cathode activation polarizations, and internal reforming/shifting reactions, among others. Dynamic outlet voltage, current, and fuel-cell-tube temperature responses of the cell to step changes in external load resistance and conditions of the feed streams are presented. Simulation results show that the fuel cell is a multitime-scale system; some of the cell output responses exhibit consecutive apparent dominant time constants, ranging from similar to 0.2 ins to similar to 40 s. They also reveal that the temperature and pressure of the inlet air stream and the temperature of the inlet fuel stream strongly affect the dynamics of the fuel cell system. The temperature of the inlet air stream has the strongest effect on the cell performance, and the effects of the inlet air and fuel velocities on the cell response are weaker than those of inlet feed pressures and temperatures. A simple control system is then implemented to control the fuel-cell outlet voltage and cell-tube temperature through manipulation of the pressure and temperature of tire inlet air stream, respectively. The results show that the control system can successfully reject unmeasured step changes (disturbances) in tire load resistance, tire velocity of the inlet air stream, and the pressure, temperature, and velocity of the inlet fuel stream.