Tham khảo tài liệu 'energy storage in the emerging era of smart grids part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 288 Energy storage in the Emerging Era of Smart Grids where J is water flux Dw water apparent diffusion coefficient membrane thickness c a pure water concentration mol l c g water concentration in the air. The water flux across the composite membrane was measured at the air flow rate of 800ml min under temperature from 303 to 353K. The water apparent diffusion coefficient calculated from Eq. 3 was showed in Figure 7. It was clearly seen that the water apparent diffusion coefficient of Nafion212 membrane was lower than that of Nafion SiO 2 composite membrane and the diffusion coefficient of comp osite membrane increased with the increase of SÌO2 content. Temperature I K Fig. 7. The water apparent diffusion coefficient of Nafion212 SiO 2 composite membrane with different content of SiO 2 as a function of temperature. Qu Li et al. 2011 Assumed that the water apparent diffu Sion coefficient of the Nafion212 SiO 2 composite membrane and temperature were consistent with Arrhenius equation that was lnDw lnD0- r I 4 Equation 4 was carried on the linear regression to Nafion212 SiO 2 composite membrane s lnDw and 1000 T as shown in Figure 8. The results showed that the lnDw was linear correlation with 1000 T in the temperature rang e from 303 to 353K. This demonstrated that the assumption was right. The apparent diffusion activation energy Ea and preexponential factor of the composite membrane was obtained through linear fit in Figure 8 listed in Table 1. The apparent diffusion activation energy of the Nafion212 membrane was higher than that of the Nafion212 SiO 2 composite membrane indicated that water diffusion was easier in the Nafion212 SiQ2 composite membrane. High Temperature PEM Fuel Cells Based on NafionD SiO2 Composite Membrane 289 Nafion212 Nafion212 SiO Nafion212 SiO Nafion212 SiO Q S 7TT 1_I---1---1--- Nafion212 Nafion212 Nafion212 Nafion212 .
