They found that local deposits in t

They found that local deposits in the cell were caused by water evaporation and the probability of the bipolar plate corrosion increased largely with accumulated water condensation. F.Migliardini et al. [29] conducted the experiments on PEMFC stacks of three different sizes. Then they analyzed humidification problems of PEMFC and considered the internal and external humidification methods. The effects on humidification methods of membrane hydration were evaluated by its power loss rate and the performance of stacks. The external humidification was effective in most operating conditions. But the effects ofexternal humidification were limited when the stacks had high temperature, low load or the membrane is in a dry state.