ACCELERATED STRESS TESTING PROTOCOLS OF PROTON EXCHANGE MEMBRANE (PEM) ELECTROLYZERS

Kurzfassung

Temperature, water flow rate, pressure and current density are the operational parameters of a Proton Exchange Membrane (PEM) electrolyzer that govern its performance. The effects of temperature and current density have been widely studied compared to water flow rate and pressure. In this work, the effect of water flow rate and pressure on electrolyzer performance, for a fixed temperature and input voltage, was studied. Initially, the individual effect of these parameters was studied, after which combinations of those parameters were studied in different orders of variation. The combination which caused the most degradation was observed and then tested further with time and cyclic variations. The most significant identification was that a variation of anode flow rate and cathode pressure caused more degradation than any other combination. Accelerated stress tests were designed, in order to investigate the effect of time on the degradation rate of the electrolyzer. All the accelerated stress tests were then compared and a degradation multiplier was formulated. Effect of time and cycling on the proportion of reversible and irreversible losses was observed and presented. Electrochemical Impedance Spectroscopy (EIS) is a non-invasive technique which measures the response of a system by applying a small sinusoidal disturbance signal. The advantage of using EIS is that the technique has the ability to distinguish between the different electrochemical processes. EIS was carried out after each test. From the literature study, the electrolyzer losses were identified and compared with experimental results. It was seen that while the ohmic and activation losses remain almost similar, mass transport losses show significant changes in all the experiments.