Relative humidity effects polarization curves

Polarization curves showing the effect of modified diffusion layers (air/Hj, 2/1.5 stoichiometry, 3.1/3.1 bara, 100/100% relative humidity, 80°C). (Reprinted from D. P. Wilkinson and ]. St-Pierre. ]oumal of Power Sources 113 (2003) 101-108. With permission from Elsevier.)... 

When used for automotive applications, fuel cells must respond to changes in the load. Changing the load alters the water production, changing the balance between water produced and water removed, resulting in a change of the membrane water content. The effect of the load resistance on the water activity can be seen in the polarization curves for the STR PEM fuel cell shown in Figure 3.9A [23]. The STR PEM fuel cell was operated in the autohumidification mode. The STR PEM fuel cell was equilibrated at 80C for 12 h with a fixed load resistance (either 0.2 or 20 fi). After equilibration, the polarization curve was obtained by sweeping the load resistance between 0.2 and 20 ft in 100 s. The relative humidity in the anode and cathode streams... 

Figure 6.7. Polarization curves for different concentrations of NO . Cell temperature 60°C, H2/air (1.2/3.3) relative humidity H2 95% and air 0% backpressure 1.5 atm [49], (Reprinted from Electrochimica Acta, 51(19), Yang Daijun, Ma Jianxin, Xu Lin, Wu Minzhong and Wang Haijiang, The effect of nitrogen oxides in air on the performance of proton exchange membrane fuel cell, 4039-44, 2006, with permission from Elsevier.)...

Fig. 2.25 Steady-state polarization curves at different humidification is observed at high current densities and relative humidities for high temperature polymer electro- low RH. Reproduced from [32] with permission of the lyte fuel cell based on Aquivion (Solvay) membrane American Chemical Society and CNR-ITAE catalysts. The effect of internal...

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