Operando investigation of the two-phase flow behavior of a zero-gap alkaline electrolysis cell using neutron radiography

The two-phase flow behavior inside a zero-gap alkaline electrolysis cell is investigated using operando neutron radiography. The cell was operated with a highly concentrated potassium hydroxide solution. The two-phase flow is evaluated at different electrolyte volume flows, current densities, and temperatures. The amount of gas inside the parallel flow channels is identified and the gas bubble velocity over the channel’s length and time is evaluated depending on the different operating conditions. The gas bubble motion requires a high degree of temporal resolution. At the Institut Laue Langevin, a high frame rate of 50 fps was achieved using the NeXT (Neutron and X-Ray Tomograph) neutron imaging instrument, which is fed by the world’s most powerful neutron source. This study demonstrates the importance and limitations of high temporal and spatial resolution in neutron radiography for the investigation of two-phase flow in electrochemical flow cells.