One-dimensional dynamic model of a PEM fuel cell for analyzing through-plane species distribution and irreversible losses under various operating conditions

Abstract

This study develops a one-dimensional dynamic model of a proton-exchange membrane fuel cell (PEMFC), using species mole fractions as shared variables to examine through-plane water and oxygen distribution. During dynamic operation, the species mole fraction difference between the cathode channel/cathode gas distribution media (cCH/cGDM) interface and the cGDM/cathode catalyst layer (cGDM/cCL) interface varies with current density. When relative humidity (RH) changes from 20 % to 90 % at 1 A/cm2, the water mole fraction difference between cCH/cGDM and cGDM/cCL increases by 33.21 %, while the oxygen mole fraction difference increases by only 3.29 %. Current density step changes cause overshoot and undershoot behavior in the water mole fraction, affecting membrane water content, especially at low RH, where it remains low and sensitive to current and temperature changes. Beyond 50 % RH, membrane water content stabilizes, with fluctuations mainly observed on the anode side. The impact of species distribution on irreversible losses was then examined.Furthermore, oxygen transport resistance increases with operating pressure, while oxygen molecular diffusion remains stable. Conversely, rising temperatures substantially improve oxygen molecular diffusion. An analysis of FC loss profiles under various temperatures (333.15K–363.15K) and RH (0%–100 %) at constant loads (0.2&1 A/cm2) shows the model's capability in determining optimized operating conditions for PEMFCs.

Keywords

• PEMFC
• Modelling
• Species distribution
• Water content
• Irreversible losses