Study Of Dynamic Characteristics Of Water Transport In Membrane Of PEMFC

Water transport in proton exchange membrane fuel cell plays an important role in output characteristic of cell. The hydration of membrane sufficiently can make the cell run well and steadily. The study of dynamic characteristics of water transport in membrane is helpful to improve the fuel cell’s performances.At first, a mathematical model of the fuel cell in steady state is introduced considering the influence of the temperature and current density. The results suggested that the anode’s water content in fuel cell enhanced with the increasing of the temperature, and the cathode water content rise with the increasing of the current density. Besides, a one dimensional dynamic model of water transport in the membrane of PEMFC is established. The water content change of the anode and cathode is taken into account as well as the Ohm loss because of the Ohm polarization.The water transport characteristics in membrane of fuel cell were analyzed in high and low current density respectively during start up. In two cases, the effect of the temperature, thickness, anode and cathode humidification are considered. The results showed the higher the temperature the better the water transport characteristics; the thinner the membrane, the better the water transport characteristics; the higher the anode and cathode humidification, the better the water transport characteristics. But the effect of anode humidification is less than that of cathode.Furthermore, the effect of operating parameters on the dynamic characteristics of water transport in membrane of PEMFC was studies during load change. The membrane water content decreased and there was the occurrence of undershoot as the current density changes increase suddenly. The absolute quantity of undershoot decreased as the temperature increased; the thinner the membrane, the less the absolute quantity of undershoot. The effect of cathode humidification on fuel cell’s loss owing to Ohm polarization was more obvious than anode humidification.In this paper, water transport characteristics in membrane and output performance of PEMFC were investigated during start up and load change. The water content distribution of membrane and ohmic over-voltage with time were simulated under different operating condition. Water transport in membrane has great significances for water management in PEMFC, the understanding of dynamic characteristics of water transport in membrane is useful to improve the fuel cell performances.