Numerical study on dynamic operating behaviors of a liquid-feed direct methanol fuel cell

A transient two-dimensional two-phase mass transport model is applied to investigate the cell dynamics of a liquid-feed direct methanol fuel cell (DMFC) in response to sudden change of cell current density. The results reveal that in response to the sudden drop of cell current density and methanol concentration, the cell voltage exhibits overshooting behavior as a result of the interaction between cathode and anode overpotentials with different time responses. The dominant factor causing the long response of cell voltages is the methanol recovery in the membrane electrode assembly which takes tens of seconds because of the sluggish methanol transport process.