Alkaline water electrolysis is important for green hydrogen production. We simulate the growth of a single hydrogen bubble on a cathode in a 30 wt% KOH solution in a narrow channel. We develop and use a sharp interface method to solve the Navier-Stokes equations, the species transport equations, and the potential equation for a tertiary current distribution. To investigate the role of the mobility of the bubble interface, three different boundary conditions are used: the no-slip, the free-slip, and the Marangoni stress condition. The surface tension depends on the local electrolyte concentration. The simulation results show that different boundary conditions lead to minor changes in electrochemical quantities but significantly affect the force on the bubble. The Marangoni boundary condition leads to a relatively large force on the bubble, which is expected to accelerate bubble detachment. This result makes plausible why the hydrogen bubbles in alkaline electrolysis are relatively small.

中文翻译：

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气液界面边界条件对碱性水电解中单氢气泡生长的影响


碱性水电解对于绿色氢气生产非常重要。我们模拟了单个氢泡在 30 wt% KOH 溶液中阴极上狭窄通道中的生长。我们开发并使用了一种尖锐界面方法来求解 Navier-Stokes 方程、物质传递方程和三次电流分布的电位方程。为了研究气泡界面流动性的作用，使用了三种不同的边界条件：无滑移、自由滑移和马兰戈尼应力条件。表面张力取决于当地的电解质浓度。仿真结果表明，不同的边界条件会导致电化学量的微小变化，但会显著影响气泡上的力。马兰戈尼边界条件导致气泡上产生相对较大的力，预计这会加速气泡分离。这一结果解释了碱性电解中的氢气泡相对较小的原因。