On the effect of operating conditions in liquid-feed direct methanol fuel cells: A multiphysics modeling approach. (15th October 2016)

• Record Type: Journal Article
• Authors: García-Salaberri, Pablo A.; Vera, Marcos
• Is Part Of: Energy. Volume 113(2016)
• Page Start: 1265
• Page End: 1287
• Publication Date: 2016-10-15
• Subjects: DMFC -- Operating conditions -- GDL compression -- Multiphysics modeling -- Parametric study; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2016.07.074
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: A multiphysics model for liquid-feed Direct Methanol Fuel Cells is presented. The model accounts for two-dimensional (2D) across-the-channel anisotropic mass and charge transport in the anode and cathode Gas Diffusion Layers (GDLs), including the effect of GDL assembly compression and electrical contact resistances at the Bipolar Plate (BPP) and membrane interfaces. A one-dimensional (1D) across-the-membrane model is used to describe local species diffusion through the microporous layers, methanol/water crossover, proton transport, and electrochemical reactions, thereby coupling both GDL sub-models. The 2D/1D model is extended to the third dimension and supplemented with 1D descriptions of the flow channels to yield a 3D/1D + 1D model that is successfully validated. A parametric study is then conducted on the 2D/1D model to examine the effect of operating conditions on cell performance. The results show that an optimum methanol concentration exists that maximizes power output due to the trade-off between anode polarization and cathode mixed overpotential. For fixed methanol concentration, cell performance is largely affected by the oxygen supply rate, cell temperature, and liquid/gas saturation levels. There is also an optimal GDL compression due to the trade-off between ohmic and concentration losses, which strongly depends on BPP material and, more weakly, on the actual operating conditions. Highlights: A multiphysics model for liquid-feed DMFCs is presented. GDL anisotropic transport, assembly compression, and ohmic contact resistances are considered. The model is successfully validated against previous experimental data. Optimum methanol concentrations, GDL compressions, and operating temperatures are reported. Oxygen-starved conditions with spontaneous hydrogen evolution in the anode are also considered.