Experimental Study of Gas Invasion Mechanism in the Porous Transport Layer of a PEM Electrolyzer

The gas invasion mechanism through an initially saturated porous transport layer (PTL) of a proton exchange membrane (PEM) electrolysis is studied. Magnetic resonance imaging (MRI) technique is used to quantify water content in the porous layer during the gas invasion for different gas and water flow rates. Instead of the real PTL made of titanium which is paramagnetic and cannot be used in the MRI, borosilicate filters with thickness, porosity, and pore size similar to the PTL were used in the MRI experiments. The MRI measurement allows acquisition of the 2D water saturation map within the porous material, which can be averaged to obtain saturation profiles in the gas flow direction. The dependence of the saturation profile on the sample properties and the water/gas flow rates are carefully analyzed to give insight into the gas invasion pattern in such porous materials. Moreover, by recording the gas pressure at the inlet and observing the bubble formation and evacuation in the water channel, more information about the gas preferential pathways, bubble appearance sites can be achieved.