1D multiphase flow modelling of a bubble-induced natural convection water electrolyser

Abstract

This study focuses on water electrolysis and aims to provide suggestions for the company XINTC Global, for the design of the electrolyser and the accompanying flow network. The most important parameters for this project are the dimensions of the cell, the geometry of the piping network, the electrode gap, the volumetric flow rate and circulation velocity. These parameters influence the performance of the cell. As a result, the production of hydrogen is optimized by fine-tuning these parameters. In addition, the performance in different electrolyser geometries is maximized assuming free circulation of the electrolyte. The geometries differ in the number of cells and the stacking arrangement and they are the single cell, single module and horizontally stacked geometries. The performance indicators are the flow velocity through the electrode gap and the volumetric velocity through the electrode gap, which is a product of the velocity, electrode gap and electrode depth. Furthermore, suggestions on the other dimensions are given, with the aim to maximize the flow rate or velocity. To study the behaviour of the electrolysis system, I developed a Python code that simulates the flow through the electrolysis cell and channel network. This numerical model is compared to an analytical model and experimental data from the literature. Finally, the simulations predicted that the optimum electrode gap width is dependent on the total number of cells. The results with the turbulent flow model, showed that the optimum electrode gaps were 1.85 mm 0.250 mm and 0.250 mm for a single module configuration with 1, 60, and 240 electrolysis cells, respectively. Moreover, the horizontal stacking arrangement of the modules, resulted in larger optimum electrode gaps, for the same number of cells.