Abstract

Hydrogen fuel cells optimization is fundamental to improve this technology and make it suitable for heavy duty vehicles. Optimization of the fuel cells spans from modifying bipolar plates geometry, improving fuel cell materials and further developing the surrounding hydrogen and air supply lines. However, one of the most fundamental aspect is the fuel cell water management, tied to the very complex multiphysics phenomena that occur at the core of the cell. In particular, the final water content is the result of the interaction between the multiphase and the electrochemistry. Understanding and simulating such phenomena is thus fundamental for engineers striving to improve fuel cells. The water content of the membrane must be high enough to ensure maximum electrical conductivity and thus optimum "stack performance". Drying out can lead to membrane degradation. On the other hand, if the humidity is too high, the cells are flooded, blocking the air and fuel flows to the catalytic layers and thus also the reactions, which leads to a decrease in efficiency. The water transport physics of fuel cells needs further R&D effort due to its complexity. Numerical modeling can improve the fundamental understanding of the phenomena. In this work a comprehensive 3D model for fuel cells is presented. The PEM fuel cell was modeled in the Siemens Simcenter STAR-CCM +. The anode and cathode GDL are modeled as a porous material, with electrochemical reactions being calculated in an infinitely thin catalyst layer. The membrane is modeled as a solid block, which includes proton and water transport with electroosmotic resistance and ohmic heating. A two-phase approach was used to model the gas mixture and the liquid water transport in the GDL and the canals. In addition, a study on various geometries and water management is to be presented. The geometries represent a sector representing patterns of typical industrial configurations. Water distribution and electric current densities are then compared.