Three-dimensional modeling of Alkaline Water Electrolyzers

Abstract

The main purpose of this paper is the development of a CFD modelling methodology for the simulation of alkaline water electrolysis. The growing concern about climate change is pushing more and more countries to facilitate ecological transition programmes. Hydrogen perfectly fits the characteristics to become one of the main actors in many industrial sectors to reduce the emission of polluting gases in hard-to-abate sectors. In this framework, hydrogen must be produced through zero-impact technologies. Alkaline water electrolysis is the most widespread technology to produce green hydrogen, and through its CFD modelling it is possible to accurately simulate the behaviour of these components and enhance their performance. In this study, two three-dimensional models have been created representing two types of alkaline electrolysis cell: the first one is a standard laboratory configuration (wide-gap), the second one is a zero-gap type. Both models are based on a two-phase model (liquid: water and potassium hydroxide electrolyte, gas: hydrogen and oxygen) using a Euler-Euler approach to describe the gas bubble flow. With these models it has been possible to investigate how temperature and electrolyte flow rate affect the production of hydrogen, with particular emphasis on the pressure effect. Increasing the pressure at which hydrogen is produced could mean a significant reduction in storage compression costs, giving new horizons to this technology.