Degree: Doctoral Student
Department: Mechanical & Industrial Engineering
Supervisor: Professor Aimy Bazylak
Pore Network Modelling and Synchrotron X-ray Radiography to Investigate Two Phase Flow in PEMFC Electrodes The porous electrodes of polymer electrolyte membrane fuel cells (PEMFCs) are made up of a catalyst layer (CL), typically coated onto the ionomer membrane, and a gas diffusion layer (GDL). GDLs are hydrophobically treated carbon fibre papers and cloths. The primary purpose of the GDL is to provide a porous electrical connection between the external circuit and reaction sites at the CL. However, when liquid water accumulates in the electrode it inhibits reactant diffusion across the GDL and can completely block portions of the reaction sites at the CL. Currently, the dominating mechanisms responsible for liquid water transport in PEMFC electrodes are unknown, restricting our ability to design high performance materials and material combinations. This research focuses on the following unknowns of liquid water transport within the GDL and CL: saturation levels and distribution within the GDL and CL during operation, liquid water formation mechanisms, wettability of the GDL, pore morphology of the GDL, and the microporous layer treatment of the GDL. The modelling tools employed are stochastic material modelling, pore-network extraction, and two-phase pore network percolation simulations. Experimental work comprises of in-situ visualization of liquid water in PEMFCs through synchrotron x-ray radiography performed at the Canadian Light Source. Work is performed in the Microscale Energy Systems Transport Phenomena group at the University of Toronto, in collaboration with the Automotive Fuel Cell Cooperation in Burnaby, BC.