Investigation of Water Transport Within a Proton Exchange Membrane Fuel Cell by Diffusion Layer Saturation Analysis

Diffusion layer saturation analysis (DLSA) is introduced in order to further investigate water transport within the cell. The analysis relies on two separate experimental processes. First, an ex-situ investigation of the relative humidity of the gas streams and their resulting pressure drop is performed. Next, multiple variables of the cathode and anode gas streams are manipulated in-situ to create an evaporative driving force to remove water out of the porous layers. Multiple gas stream settings are investigated as well as the temperature set point of the cell. The ex-situ pressure drop data is used to infer how much water is being removed from the system and to begin to estimate an overall water balance. Multiple cathode and anode GDL configurations are tested in order to further investigate initial saturation conditions of the GDLs. By coupling the voltage results to the calculated water removed from the system, it can be seen which configurations had low initial voltage due to GDL oversaturation. The potential for DLSA both as a diagnostic tool and an investigative technique into multiphase flow in the porous layer is demonstrated.