• A bio-inspired honeycomb microchannel structure for membraneless electrolysis is proposed • Variable lengths of micro-channels are estimated using an analytical model • CFD simulations are performed to evaluate flow uniformity and pressure drop • Bubble force balance is performed to evaluate the bubble departure diameter and movement direction Membraneless electrolysis (ME) technology offers several advantages compared to conventional electrolysis technologies. However, removal of the membrane also leads to a reduction in the purity of the hydrogen. In general, circular electrodes are used to reduce gas crossover and to produce a higher-purity hydrogen, because it is necessary to create a uniform flow across the pores/channels. In this study, a novel bio-inspired honeycomb ME cell with specifically tailored micro-channels is proposed and investigated. An analytical model based on energy conservation was developed to estimate the length of each micro-channel, and a computational fluid dynamics model was used to investigate the pressure drop and flow uniformity in each design. Additionally, to investigate the departure diameters of bubbles, and to estimate the bubble trajectories after departure, a force balance study was performed. The results show that the application of properly designed micro-channels with appropriate length and hexagonal cross-section can result in a flow uniformity index of 95.0% which is significantly higher than that of channels with uniform length and circular cross section, although this improvement comes at the cost of a higher pressure drop. The study also shows that the departure diameter of most bubbles is smaller than 60 microns.
Sadeghi et al. (Wed,) studied this question.