Eulerian Two-Fluid Model of Alkaline Water Electrolysis for Hydrogen Production

Abstract

<jats:p>Hydrogen storage is a promising technology for storage of renewable energy resources. Despite its high energy density potential, the development of hydrogen storage has been impeded, mainly due to its significant cost. Although its cost is governed mainly by electrical energy expense, especially for hydrogen produced with alkaline water electrolysis, it is also driven by the value of the cell tension. The most common means of electrolyzer improvement is the use of an electrocatalyst, which reduces the energy required for electrochemical reaction to take place. Another efficient means of electrolyzer improvement is to use the Computational Fluid Dynamics (CFD)-assisted design that allows the comprehension of the phenomena occurring in the electrolyzer and also the improvement in the electrolyzer’s efficiency. The designed two-phase hydrodynamics model of this study has been compared with the experimental results of velocity profiles measured using Laser Doppler Velocimetry (LDV) method. The simulated results were in good agreement with the experimental data in the literature. Under the good fit with experimental values, it is efficient to introduce a new physical bubble transfer phenomenon description called “bubble diffusion”.</jats:p>

Bubble-induced convection stabilizes the local pH during solar water splitting in neutral pH electrolytes

“…54,71 In this case, additional ohmic voltage losses due to the presence of gas bubbles have to be considered, as previously demonstrated in the multiphase fluid dynamics simulations of alkaline electrolyzers operating at high current density. 21,[72][73][74] Also, optical losses due to the presence of gas bubbles need to be considered when the illumination of the photoelectrodes occurs through the electrolyte layer, such as in tandem photoelectrochemical devices. 28,30,66 In order to fully exploit the bubble-induced convection, the abovementioned competing negative effects need to be quantified and carefully minimized depending on the target device configuration.…”

CFD Modeling and Experimental Validation of an Alkaline Water Electrolysis Cell for Hydrogen Production

“…The accuracy of the CFD model was also studied by varying some of the most critical operating parameters in an alkaline water electrolysis system. Additionally, the mean relative absolute difference error (MRAD error ) was calculated according to Equation (20) in order to ensure the accuracy and validity of the proposed model [5]:…”

“…Zarghami et al [19] used an Euler-Euler model in FLUENT to simulate the multiphase flow in an alkaline water electrolyzer and compared the results to existing experimental data. Recently, Le Bideau et al [20] developed a two-phase hydrodynamics model and validated the results with the experimental velocity profiles measured using the Laser Doppler Velocimetry (LDV) method.…”

Evolutionary Design Optimization of an Alkaline Water Electrolysis Cell for Hydrogen Production

“…This value is around 1.23 V at atmospheric pressure at 25 • C. Increasing temperature and decreasing the pressure decrease this minimum cell voltage. The majority of previous studies have focused on finding a cheap, robust and electroactive electrode material or electrocatalyst to decrease the activation overpotential, which are the second and third terms in Equation (1). There is also another research trend aiming at increasing efficiency, which is to reduce an ohmic resistance and surface coverage through electrolyzer design by means of simulations or experiments.…”

“…There is also another research trend aiming at increasing efficiency, which is to reduce an ohmic resistance and surface coverage through electrolyzer design by means of simulations or experiments. Previous studies modeled the void fraction and velocity distribution [1][2][3][4][5] or the cell voltage [6]. There exist only few studies about optimization of this process.…”