Experiments and microsimulation of high-pressure single-cell PEM electrolyzer

Abstract

Direct hydrogen production at high pressure by the proton exchange membrane (PEM) can improve the economy of the entire hydrogen-chain. A multi-physical model of a high pressure single-cell electrolyzer is established and the heat transfer, mass transfer, and electrochemical processes are described. The water permeation flow rate is simulated accurately using experimental data obtained under 0-700 bar pressure difference. The double layer effect and mass transfer lag effect are considered in the dynamic model in terms of different time constants. Polarization curves exhibit good consistency at different temperatures and high cathode pressure, and the average the sum of squares due to error (SSE) is less than 0.01. Different film thicknesses correspond to different safe operating zones (hydrogen concentration in oxygen below 2%). A membrane thickness of 250μm allows the cathode pressure to increase to approximately 120 bar, and the minimum operating current density should not be less than 0.2 A/cm2. Increasing the cathode pressure to 200 bar can reduce the water content on the hydrogen side by more than 19.5%. Finally, the temperature control model of circulating water in the electrolysis cell is calibrated and verified by experiments, and the steady-state error is less than 2.5%.