Unconventional Plumbing in PEM Electrolyzer Cells

• Nicholas Hackett, Mechanical Engineering, University of Delaware
• Sergio Herrera, Mechanical Engineering, University of Delaware

• Ajay Prasad, Department of Mechanical Engineering, University of Delaware

Hydrogen electrolyzer cells are a crucial component in the production of hydrogen and for the future of clean energy. Under normal operating conditions though, electrolyzers can experience a process known as crossover where hydrogen produced on the cathode side of a cell can backflow through the Nafion membrane inside of the cell to the oxygen outlet due to pressure. If the hydrogen in oxygen concentration reaches just 4%, the mixture becomes explosive which raises safety and economical concerns. To get around this the Norwegian company, Hystar, has patented an idea that involves flooding the cathode with water and the anode with humidified air to dilute the hydrogen crossover concentration. Our research has focused on testing Hystar’s claims and seeing the impacts in cell performance with this unconventional setup. Our experiments have used an MEA with a 2.25cm^2 active area and we have collected data at varying flow rates of humidified air with both Nafion 115 and 117 membranes. So far, our research points to cell performance decreasing dramatically in the unconventional setup with little further affect in performance above 400ccm of humidified air at 80c. Below 400ccm performance noticeably decreases as the membrane becomes more dehydrated and relies more on water diffusing from the cathode side. This disproves Hystar’s claim that performance remains similar with an unconventional setup compared to the conventional plumbing. Future research will focus on testing performance with thinner membranes and measuring hydrogen crossover in pressurized cells.