Numerical modeling of liquid water transport inside and across membrane in PEM fuel cells

Abstract

Liquid water transport inside a proton exchange membrane (PEM) fuel cell plays a crucial role in cell performance and durability. In this paper, a two-phase multi-dimensional PEM fuel cell model has been developed to properly handle water transport inside and across the polymer membrane in both absorbed water phase and free liquid phase. The numerical model has been employed to investigate effects of the cell operating current and cell temperature on liquid water distributions on both anode and cathode sides, as well as inside the membrane. Numerical results reveal that liquid water transport inside and across the polymer membrane plays an important role in PEM fuel cell water distributions. Increasing the fuel cell operating current density would result in more liquid water accumulation on both anode and cathode sides, a phenomenon dictated mainly by more water production. However, liquid water evaporation on the anode side also makes a profound impact at an increased operating current density. Decreasing the cell operating temperature, particularly from 80 to 60 °C, would result in more liquid water inside the fuel cell. This phenomenon is mainly controlled by the decreased liquid water evaporation process on both anode and cathode sides. Further decreasing the cell boundary temperature from 60 to 40 °C would only lead to very slight liquid water increase. The calculated results show qualitative agreement with available neutron imaging data. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.