Evaporation analysis of different fuels in evaporator coil of steam reformer for stationary PEM fuel cell systems

Numerical simulations are performed to investigate the evaporation behavior of various fuels in the evaporator coil of the steam reformer used for hydrogen gas production purposes in a stationary proton exchange membrane (PEM) fuel cell system. The simulations consider five different fuels, namely three methanol-water mixtures (50%:50%, 62%:38% and 75%:25%), pure methanol, and pure ethanol, respectively. For all operating temperatures, the pure ethanol fuel exhibits the lowest flow rate due to its relatively higher dynamic viscosity. For the methanol-water fuel mixtures, the evaporation temperature increases from 473 K to 547 K as the methanol content increases from 50% to 75%. Moreover, the pure methanol and ethanol fuels have evaporation temperatures of 609 K and 713 K, respectively. Of the five fuels, the pure ethanol fuel achieves full vaporization (i.e., no water content) within the shortest flow distance (543 mm). Moreover, the outlet temperature of the vaporized ethanol (713 K) is the highest of the considered fuels. Overall, the simulation results indicate that pure ethanol yields the highest hydrogen production efficiency, and is therefore the most suitable fuel for the steam-reforming production of hydrogen gas in PEM fuel cell applications.