Optimization of porous transport layer for overall performance improvement in unitized regenerative fuel cell under clamping pressures

The porous transport layer (PTL) in a Unitized Regenerative Fuel Cell (URFC) is essential for achieving high electrochemical performance and operational stability. It facilitates gas diffusion, regulates water-gas transport, and supports electrochemical reactions. Clamping pressure profoundly influences URFC performance by altering key properties such as porosity, permeability, electrical conductivity, and the contact resistance between the PTL and bipolar plate. Thus, the interplay between clamping pressure and the PTL is critical for optimizing URFC performance. This study focuses on investigating the effects of clamping pressure on URFC performance, uncovering key principles for optimizing PTL structural properties to enhance the overall performance of the URFC. Simulation results based on a two-dimensional finite element model and a three-dimensional two-phase electrochemical model reveal that clamping pressure induces asymmetric mechanical behavior in the PTL on either side of the URFC. As clamping pressure increases, significant changes occur in transport properties, which strongly affect mass transfer processes in the URFC. Furthermore, the study integrates Box-Behnken design, artificial neural networks, and the non-dominated sorting genetic algorithm-II method to develop a precise regression model for identifying optimal design solutions. Under the optimized configuration, the URFC's input power density and output power density increased by 4.08 % and 9.47 %, respectively, while the round-trip efficiency improved by 14.13 % compared to conventional configurations.