Reduced-Order Physics Modeling and Power Performance Analysis of Direct Methanol Fuel Cells

Abstract

Direct methanol fuel cells (DMFCs) are attractive for portable, low-power applications because liquid methanol enables compact fuel storage and a simplified, potentially passive balance-of-plant. Performance is constrained by sluggish methanol oxidation kinetics, membrane/contact ohmic losses, and mass-transport limitations in porous layers. We develop a physics-based one-dimensional reduced-order model (ROM) to rapidly predict polarization and power with explicit voltage-loss decomposition. Cell voltage is written as the reversible potential evaluated at bulk/channel reference states minus additive activation, ohmic, and transport-induced concentration losses; the concentration term represents the bulk-to-interface Nernst shift under a no-double-counting convention. A lumped thermal transient submodel enables load-dependent temperature screening. The model uses effective single-phase transport closures with well-mixed bulk/channel reference states. Methanol crossover, cathodic mixed-potential losses, liquid-water flooding, and resolved multiphase transport are not included. Therefore, the reported efficiency and high-current predictions represent gross reduced-order estimates within the stated model scope. The ROM reproduces a bell-shaped power–current-density curve with a peak power density of 207 W/m² at i = 1563 A/m². At a practical point near 75% of peak power density, it predicts V = 0.2361 V, i = 679.6 A/m², and P = 160.5 W/m², corresponding to 20% efficiency. Loss analysis indicates activation losses dominate most conditions, whereas mid-load operation provides a balanced trade-off among power, efficiency, and thermal safety. The framework is computationally efficient, enabling rapid parametric studies and design screening.