Analysis of PEM fuel cell stacks using an empirical current-voltage equation

An empirical equation was developed to describe the electrode processes (activation, ohmic and mass-transfer) of PEMFC stacks over the entire current range. The potential-current and power-current curves of a strip PEMFC stack were fitted with the empirical equation under a variety of experimental humidity, temperature and stack length conditions. The concept of mass transfer impedance was defined mathematically in the present research. For the strip PEMFC stack, mass transfer impedance was only important at high currents. With decreasing humidity the mass transfer impedance increased considerably. With increasing temperature or stack cell number the mass transfer impedance increased only slightly.