Understanding Liquid Water Distribution and Removal Phenomena in an Operating PEMFC via Neutron Radiography

Abstract

A proton exchange membrane fuel cell (PEMFC) was imaged using neutron radiography under pseudo steady-state operating conditions to determine the total liquid water content of the cell and the liquid water content distribution across the active cell area as a function of cell temperature, current density, and cathode air flow rate. A simple cathode-based model was formulated to rationalize the observed dry inlet regions which were most strongly influenced by temperature and current density. Between temperatures of 40 and and current densities of 0.5 and , the outlet gas temperature was measured to be greater than the cell bulk temperature. This small temperature difference was enough to account for drying of 20–40% of the cell area, depending on the bulk cell temperature. For the cell construction used in this work, the temperature and cathode stoichiometric flow had a marginal effect on the polarization curve performance but had a large effect on the liquid water content and distribution within the cell.