Transient response of PEM fuel cells during sudden load change

Performance of the PEM fuel cells strongly depends on the stack temperature, because operating temperature of the cell has substantial impact on water management, electrical power and durability of the cell. In vehicle applications fuel cells operate under load change conditions. Sudden load changes may result in improper water management and reactant starvation phenomena due to the slow response of the cell to load change, which results in performance loss and short lifetime. So understanding the dynamic behavior of PEM fuel cell is essential to achieve longer fuel cell lifetime and better performance. In this article a transient along the channel model has been developed to investigate temperature variation in anode, cathode gaseous stream and fuel cell stack. This lumped model is also capable of predicting the time history response in anode, cathode and stack temperature as well as water vapor and reactant partial pressure in flow channels and output cell voltage when a sudden change in the current load demand occurs. Results from this model show that solid temperature is mainly affected by the generated heat due to the electrochemical reaction. It is found that during load change, an appropriate water management can sustain maximum conductance in the membrane so that voltage drop in the cell due to the membrane resistance is minimized.