Results of the Hydraulic Permeation Model

The hydraulic permeation model in Eikerling et al. (1998, 2007a) assumed a negligible contribution of diffiisional water flux. It is valid at sufficiently high water content. The model helped rationalizing main dependences of the critical current density on membrane parameters. A 5-function-like pore size distribution dk r)/dr = itmaxS (r - ri), which is completely determined by the maximum water uptake A- ax. and by the first moment of the pore size distribution (i.e., the average pore size), r, provided an explicit expression for jpc.  

The theoretical analysis of the hydraulic permeation model provided an expression for the current density jps at which membrane dehydration commences  

Below jps, the PEM remains in a fully saturated state and it performs like a linear ohmic resistance. According to Equation 5.35, two modes of water management can be applied to compensate for electro-osmotic drag and, thus, keep the PEM well-hydrated. Sufficient replenishment of water in the membrane can be accomplished either by providing a steady external water supply, jw ridj, from the anode side 

V is dependent upon whether product water is removed predominantly via cathode (v 0) or anode (v = 1/2). 

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