Modeling and analysis of an integrated power system based on methanol autothermal reforming

The integrated power system under consideration, consists of the fuel processor (reformer and preferential oxidation reactors), the fuel cell and the heat management system. In the reformer reactor, methanol, air and water are co-fed to produce hydrogen under autothermal conditions. The produced hydrogen due to the high content of CO (>5000 ppm), is treated in the preferential oxidation reactor (PROX) for the CO minimization at acceptable levels (>50 ppm). After the oxidation clean-up step, the anode of the polymer electrolyte membrane (PEM) fuel cell is fed with the reformate gas (~60-65% H₂, ~15-25% CO₂, ~15-20% N₂, ~1-3%CH₃OH and traces of CO). The present paper is focused on the mathematical analysis of the main subsystems of the integrated power unit. The two reactors are modeled via a system of partial differential equations (PDE´s) and the species flowrates and reactor temperature are analyzed along the length of each reactor. Moreover, the PEM fuel cell voltage-current characteristic is modeled via a non-linear equation that depends on the mass & energy balances (ordinary differential equations) of the concerned species. Finally, the heat management system is analyzed in order to provide insights for future control studies that will depend on the developed mathematical model (model-based control).