Sizing Direct Methanol Fuel Cells for 12/24V Portable Backup Using a Semi-Empirical Polarization Model

A computational sizing tool was developed for direct methanol fuel cells (DMFC) intended for portable backup power in 12/24 V buses. A semi-empirical polarization model was implemented in MATLAB that combines the reversible term with activation, ohmic, and transport losses, and includes a penalty for methanol crossover. The algorithm delivers the design pair (N, A) that simultaneously satisfies the target power and voltage and estimates methanol consumption and autonomy using Faraday's law. Dynamic verification in Simulink, under variable load profiles, showed that the selected designs keep the bus within tolerance and avoid transport-limited operation. Temperature-concentration sweeps outlined stable operating zones useful for sizing. The workflow reduced the risk of oversizing and generated reproducible artifacts applicable to telecommunications nodes and other 12/24 V loads.