Polymer Electrolyte Fuel Cell Model

TLDR

The study presents an isothermal, one‑dimensional, steady‑state model of a polymer electrolyte fuel cell with a 117 µm Nafion® membrane. The model uses laboratory‑measured water diffusion, electro‑osmotic drag, sorption isotherms, and membrane conductivity as functions of water content. The model predicts a net water‑to‑proton flux ratio of 0.2, lower than the fully hydrated electro‑osmotic drag coefficient, and shows that membrane resistance rises with current density, highlighting the benefit of thinner membranes; these predictions were experimentally verified.

Abstract

We present here an isothermal, one‐dimensional, steady‐state model for a complete polymer electrolyte fuel cell (PEFC) with a 117 Nafion® membrane. In this model we employ water diffusion coefficients electro‐osmotic drag coefficients, water sorption isotherms, and membrane conductivities, all measured in our laboratory as functions of membrane water content. The model predicts a net‐water‐per‐proton flux ratio of 0.2 under typical operating conditions, which is much less than the measured electro‐osmotic drag coefficient for a fully hydrated membrane. It also predicts an increase in membrane resistance with increased current density and demonstrates the great advantage of a thinner membrane in alleviating this resistance problem. Both of these predictions were verified experimentally under certain conditions.