Performance Model of a Proton-Exchange Membrane (PEM) Operating in Steady-State Conditions with Aspen HYSYS®

Nowadays, Hydrogen is considered an important energy vector through which the decarbonization process can be carried out if it is produced by Water electrolysis using renewables. Then, Hydrogen is stored for performing medium- and long-term storage, which is suggested for those sources that face considerable electricity production variability throughout the days/months like renewables, and sent to Fuel Cells (FCs) for producing again electricity. The coupling of the electrolyzer, storage, and FC constitutes an integrated Hydrogen system. This work presents a model of a 5 kW-Proton Exchange Membrane Fuel Cell (PEMFC), which has been developed in Aspen HYSYS®, to evaluate its performance by varying its operating conditions (e.g., current density, temperature, and pressure). The simulation is based on the determination of a semi-empirical mathematical model of the electric potential related to a single 25 cm2 cell through the regression of experimental data taken from the scientific literature. Normal Root Mean Square Errors (NRMSEs) were obtained by the comparison between the results of the electric potential model of the single cell and the experimental ones, showing a good agreement. The model developed in Aspen HYSYS® allows to predict the behaviour of the PEMFC by identifying the optimal conditions in terms of temperature and pressure. Results showed that the PEMFC performance improves by increasing the temperature up to 80°C, while it is not suggested to operate at pressure values higher than 3 atm due to a lower net electric power and overall system electric efficiency.