Experimental study of gas humidification with injectors for automotive PEM fuel cell systems

A scaled gas humidification system using injectors for PEM fuel cell vehicles was developed and the humidification performance was evaluated under various operating conditions. The humidification system consists of an injector, a duplex enthalpy mixer and a water management apparatus. A dew point meter of the chilled mirror type was used to measure the humidity of the air and the hydrogen. Humidification performance was evaluated by measuring the dew point temperature of the humidified gases. Humidification performance was observed to be critically affected by the temperature of injected water and the gas flow rate in this study. The dew point of the humidified gas rose when the temperature of injected water increased, however, it dropped when the gas flow rate was increased. Experimental results show that the outlet temperature was 58.4 °C, dew point temperature of the humidified air reached 54.0 °C when the injection water temperature was 69.5 °C with the room temperature air flow rate of 200 L min−1. Inlet gas temperature also affected the humidification performance and response time. In addition, a 50 cm2 PEM fuel cell was tested to verify the effectiveness of the devised humidifier. When operated at 65 °C, the fuel cell showed an operating voltage of 0.5 V at a current density of 600 mA cm−2.