Preliminary theoretical and experimental analysis of a Molten Carbonate Fuel Cell operating in reversible mode

•A single Molten Carbonate Fuel Cell operating in reversible mode.•Thermoneutral conditions for a Molten Carbonate Electrolysis Cell.•Numerical analysis on the performance of MCFC operating in reversible mode.•Hydrogen production by Molten Carbonate Electrolysis Cell. An isothermal electrochemical model of a Molten Carbonate Fuel Cell (MCFC) operating in reversible mode is presented. Firstly, the model has been fitted with experimental data of a single MCFC operating only in fuel cell mode. Then, the MCFC model was used to calculate the overpotentials of the cell operating as electrolyzer. Additionally, equations were added to calculate the concentration overpotentials in the fuel and oxygen electrode, useful to improve the prediction of the limiting current densities where the fuel started to lack. The validation of the model simulating the operation of the cell in reversible mode was carried out with experimental data obtained on a single MCFC operating in reversible mode. The results indicate that in general the model predicts cell performance well when several parameters like temperature, composition in the fuel electrode and composition in the oxygen electrode are varied around a nominal operating point. Concerning the electrolysis operation of the cell, the theoretical thermo-neutral voltage is presented, as well as the power consumption and hydrogen production when the cell operates at the thermo-neutral voltage. Finally, the hydrogen production was validated comparing the experimental and numerical hydrogen molar fraction present at the exit of the fuel electrode.