Experimental investigation of CO tolerance in high temperature PEM fuel cells

In the present work, the effect of operating a high temperature proton exchange membrane fuel cell (HT-PEMFC) with different reactant gases has been investigated throughout performance tests. Also, the effects of temperature on the performance of a HT-PEMFC were analyzed at varying temperatures, ranging from 140 °C to 200 °C. Increasing the operating temperature of the cell increases the performance of the HT-PEMFC. The optimum operating temperature was determined to be 160 °C due to the deformations occurring in the cell components at high working temperatures. To investigate the effects of CO on the performance of HT-PEMFC, the CO concentration ranged from 1 to 5 vol %. The current density at 0.6 V decreases from 0.33 A/cm2 for H2 to 0.31 A/cm2 for H2 containing 1 vol % CO, to 0.29 A/cm2 for 3 vol % CO, and 0.25 A/cm2 for 5 vol % CO, respectively. The experimental results show that the presence of 25 vol % CO2 or N2 has only a dilution effect and therefore, there is a minor impact on the HT-PEMFC performance. However, the addition of CO to H2/N2 or H2/CO2 mixtures increased the performance loss. After long-term performance test for 500 h, the observed voltage drop at constant current density was obtained as ∼14.8% for H2/CO2/CO (75/22/3) mixture. The overall results suggest that the anode side gas mixture with up to 5 vol % CO can be supplied to the HT-PEMFC stack directly from the reformer.