E.C.A.S

Polymer electrolyte membrane fuel cells need humidification for proper operation. A membrane humidifier humidifies the gas supplied to the cell. Additional power is not required; however, the large pressure drop and large volume are disadvantageous. To minimize the role of the humidifier, the pressurized operation and water storage process (WSP) was adapted during dry start-up to accumulate the water generated by the reaction. A segmented cell was used. The relative humidity of the discharged gas was analyzed at the cathode outlet. For extreme dry conditions, dehydrated hydrogen and air at 30 °C and 50 °C, respectively, were used. The fuel cell showed easier hydration in the pressurized operation; the performance of the dry start-up improved under high operating pressure. The WSP was effective for all pressure condition, but its effect could not be maintained for high temperature dry start-up. Because water accumulation in the cell at high pressure facilitates hydration, successful dry start-up is possible at high operating temperatures. The dew point temperature measurement of the outlet gas confirmed that water generated by the chemical reaction accumulated in the cell, rather vaporization and discharge to the outlet. Thus, the role of the humidifier in the fuel cell system was minimized.