Ohmic Resistance Measurement of Bubble Froth Layer in Water Electrolysis under Microgravity

Abstract

Galvanostatic water electrolysis was conducted in and solutions under microgravity. The corresponding terrestrial experiments employed two kinds of electrode configurations: a vertical cathode and downward-facing horizontal cathode-over-anode (C/A) arrangement. The latter configuration was designed to simulate the microgravity condition. The ohmic resistance of the gas bubble dispersion zone near electrodes was measured by the current interrupter method and compared for these three different cases. The transient variation of resistance for C/A configuration behaved similarly to that under in , but the resistance varied more slowly in . When water electrolysis was conducted with a vertical plane cathode under , the resistance reached an essentially constant value within a few in , whereas the resistance increased linearly for a few seconds, followed by a zig-zag variation in . Water electrolysis under resulted in stable froth layer formation, and the accompanying ohmic resistance increased in linear proportion to the froth layer thickness. The contributions of electrode surface coverage by bubbles and electrolyte-phase bubble void fraction to the ohmic drop were also assessed. These parameters were compared with corresponding values in terrestrial experiments analyzed by Balzer and Vogt.