Modeling the Dynamics of the Proton Exchange Membrane Water Electrolyzer Pressure

To simulate the startup, shutdown, standby, and variable operation of Proton Exchange Membrane Water Electrolyzer (PEMWE) systems, it is necessary to model the dynamics of the operating pressure on the hydrogen side (cathode). A simple mathematical model of the cathode pressure has been developed, parametrized, and validated against dynamic high pressure data from the operation of a small-scale PEMWE system laboratory at the Institute for Energy Technology (IFE). The developed model described the actual system dynamics at different current inputs and pressure setpoints. Various equations of state (EoS) for hydrogen gas were compared and the results suggested that hydrogen should be modeled as a real gas at high pressure. The methodology presented in this work is applicable to other PEMWE systems, and the procedure for model parametrization is described in detail.