In-Situ Measurement of Liquid Water Saturation Level in the Gas Diffusion Layers of a PEM Fuel Cell

The gas diffusion layer (GDL), which is located between the catalyst layer and gas channel, can greatly affect the transport rates of reactant/product gases to and from the catalyst layers. During operation water generated in the cathode catalyst layer by the oxygen reduction reaction is transported out of the fuel cell through the cathode GDL to the gas flow channel. Excessive liquid water accumulation in the GDL can affect the transport rate of oxygen from the gas channel to the catalyst layer. Consequently, the ability to measure the liquid saturation level in the GDLs of a PEM fuel cell during operation is of great importance. It allows us to study the effect of the morphological and wetting properties of a GDL on the liquid water saturation level and the transport rate of liquid water in the GDL and to determine the effects of the liquid water saturation level in the GDL on the performance of the fuel cell. The measurements can also be used to validate the predictions of fuel cell mathematical models. This presentation will discuss the fuel cell configuration and the experiments used to measure the liquid water saturation level in a GDL in a PEM fuel and its effects on the performance of a PEM fuel cell during operation.