Computational fluid dynamics (CFD) has been employed extensively for modeling fuel cells, but electrolysis has lacked this degree of attention in literature. As electrolysis commercialization advances, the desire to use numerical methods to aid the engineering process grows. The work described in this presentation aims to link channel/manifold geometry, porous media design, and operating conditions to cell performance in the context of mass transport and identify important unknown input quantities to which models are particularly sensitive. CFD is applied to electrolysis systems to quantify the impact of two-phase flow patterns and porous media properties on energy losses, primarily those linked directly to the presence of the gas phase.

3D models for proton exchange and alkaline electrolysis devices are summarized. For proton exchange electrolysis, a homogeneous two-phase model was built in order to estimate the species composition at the anode and how operating conditions and porous transport layer (PTL) properties influence distributions. The model suggests that cell performance is particularly sensitive to the evaporation rate and PTL permeability when the contribution of the gas-phase reaction is considered. A similar model was applied to alkaline diaphragm electrolysis to study effects of the manifolds on the flow distribution and thereby local performance. Current and gas crossover were correlated with cell geometry and altered by the cell potential and feed rate.