Humidified feeds

In addition, the models demonstrated that the water balance is important and can alter potential and reactant location. For example, the reaction distribution is closer to the channel than the rib near the inlet regions for humidified feeds. The reason is that, as the water moves from anode to cathode, there is more flooding, but the movement of water in this direction decreases along the channel because of lower current densities associated with lower oxygen... 

Jones C.W. and Kotos W.J., Characterization of ultramicroponous caibon membranes with humidified feeds, Ind. Eng. Chem. Res. 54 158 (1995). 

Water is produced at the cathode by the cell process and can enter the cell as part of (humidified) feed streams. Water is transported in the PEFC through the membrane from anode to cathode by electroosmotic drag, that is, by a water flux associated with the protonic current. The flux of water due to electroosmotic drag (moles cm-2 sec-1) is given by ... 

In other words, for relatively small currents unaffected by transport limitations across the GDL (Figure 15.26), i.e., i im,L, we may expect the polarization curve to be linear, with the y-intercept, or OCV, equal to the Nemst term on the RHS, as seen in Figure 15.27 (Onda et al., 2007) for a pure H2 (though humidified) feed, i.e., for H2 pumping or compression. 

Jones CW, Koros WJ (1995) Characterization of ultramicroporous carbon membranes with humidified feeds. Ind Eng Chem Res 34 (1) 158-163... 

Jones CW, Koros WJ (1994) Carbon molecular sieve gas separation membranes- I. Preparation and characterization based on polyimide precursors. Carbon 32 (8) 1419-1425 Jones CW, Koros WJ (1995) Characterization of ultramicroporous carbon membranes with humidified feeds. Ind Eng Chem Res 34 (1) 158-163... 

Flat films are the most convenient configuration for laboratory tests of membranes, and in previous work we reported that silver-exchanged Nafion N-117 flat films gave a very good selectivity to ethene over ethane for a humidified feed at atmospheric pressure (2), (3), Table I shows that the water content in these membranes can be adjusted by a swelling procedure, and that this affects the diffusivity and the equilibrium constant for the ethene-silver ion co-ordination within the polymeric membrane. 

Preliminary fuel cell evaluations were performed on the 2,5-PPBl membrane from the PPA process and are shown in Fig. 20. All of the tests were conducted on non-humidified feed gases and performed rehably imder these completely dry conditions. 

Moore TT, Vo T, Mahajan R, Kulkami S, Hasse D, Koros WJ. Effect of humidified feeds on oxygen permeability of mixed-matrix membranes. J Appl Polym Sci 2003 90(6) 1574—80. 

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