  A Proton Exchange Membrane Fuel Cell (PEMFC) provides stable, emission-free,
high-efficiency power. Water management and durability of PEMFCs are directly
affected by transport phenomena at the cathode side. In the present study,
transport phenomena are investigated and optimized in a tapered parallel flow
field. Main channels in the flow field are tapered, which increases limiting
current density by 41%. Two objectives, i.e. water saturation and transport
resistance, are considered metrics for transport phenomena in a tapered
parallel flow field PEMFC. Operating pressure, temperature, stoichiometries at
both sides, and the porosity of gas diffusion layers are selected as parameters
to be optimized. Two functions are generated for objectives by integrating 3D
multiphase-flow computational fluid dynamics and Response Surface Methodology.
Multi-Objective Optimization (MOO) is carried out with two different methods.
Multi-Objective Particle Swarm Optimization (MOPSO) and Non-dominated Sorting
Genetic Algorithm II (NSGA-II) are employed to produce two challenging Pareto
fronts. The results demonstrate that MOPSO performs better than NSGA-II. MOPSO
recognized quite the same Pareto front with lower runtime. In the last step,
the Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) is
used to select an optimum point from the Pareto front. The results are compared
against experimental data, and good correspondence is observed. The optimum
features are temperature 323, pressure 1 atm, anode stoichiometry 3, cathode
stoichiometry 2.62, and porosity 0.68. The porosity and pressure played the
most significant roles in determining water saturation and resistance.
