Heat and mass transfer effects in PEM fuel cells

Thermal and water management procedures in proton exchange membrane (PEM) fuel cells that influence stack performance are described. The characteristics of ion exchange membranes, mass and heat transfer effects, and thermal effects are discussed. Various design options for successful PEM stack operation are proposed. Humidification strategies result in opportunities both for thermal control and for maintenance of appropriate ionic conductivity throughout active cell areas. Dehydration of anode gases can be altered by two approaches: increased water permeability within the polymer or repeated humidification by the introduction of additional water, perhaps as a supersaturated feed, or as the result of additional sequential humidification along the utilization path. The results predict that high-current-density, stable performance is feasible for a variety of different PEM options including hydrogen-oxygen, hydrogen-air and reformate-air