Computational fluid dynamics based modelling of a proton exchange membrane fuel cell system

In this thesis, multiphysics modelling of a Proton Exchange Membrane Fuel Cell (PEMFC) stack was performed. The stack is made up of 42 identical layers, and each individual layer has a surface area of 26.25 cm2. Multiphysics modelling has been done based on one of the individual layers, by further defining a unit cell of 0.72 cm2. The multiphysics model of the unit cell described, constructed in 3-D by using Comsol Multiphysics software, has been solved in the range of 0.4 - 0.9V. Single phase flow, constant temperature and steady state were chosen as modelling conditions and gravity effect was ignored. Bipolar plate, gas diffusion layer, electrodes and membrane, which are the physical components of the unit cell described, have been separately defined within the multiphysics model. The characteristic physical data required in the modelling process has been derived from the data provided by the manufacturer when available or otherwise by the related literature. Together with the 3-D geometric model and the physical characteristics, the physical processes taking place within the cell have been described by the appropriate mathematical equations. The main variables-such as the concentration of oxygen and water at the cathode, the concentration of hydrogen and water at the anode and current density, electric potential and overpotential, have been acquired from the solutions of the equations in the model. The polarisation curve also obtained from the model has been compared to the curve provided by the manufacturer.