Mass Transfer Characteristics Inside PEMFC and its Unsteady Power Generation Analysis

Water management factors such as diffusion coefficient and electro-osmotic coefficient of water vapor through MEA have been measured in our previous report, since these factors have important effects on performance of PEMFC. For unsteady analysis, more factors such as water content of MEA and mass transfer coefficients at both side of GDL boundary must be known. Then we have measured the water content of MEA and unsteady mass transfer coefficient between MEA and GDL. Since the local water transfer inside the PEMFC is quite difficult to be measured, so that the three dimensional analysis of PEMFC has been performed to estimate the mass transfer coefficient between channel and GDL. Then, unsteady power generation analysis with those measured mass (water) transport factors has been conducted. The computed results such as cell voltage transient response, current distributions, and membrane resistivity distributions are compared and agreed well with the measured results.