CFD modelling and risk assessment of accidental hydrogen release in a desktop PEM electrolyser enclosure

Abstract

This study investigates the potential risk associated with accidental hydrogen (H 2 ) release in an in-house developed desktop proton exchange membrane (PEM) electrolyser using experimental validation and computational fluid dynamics (CFD). Different release pressures of 1, 2, 4 and 6 bar were studied to determine the H 2 dispersion across the enclosure. The effectiveness of air ventilation of 1 m/s in mitigating accidents was evaluated. CFD simulations reveal that the release pressure and ventilation play a critical role in H 2 distribution, and hence the potential for safety concerns. An increase in the release pressure leads to an increase in the concentration of H 2 and creates potentially dangerous zones. The maximum concentration reached 23.38 vol% in the experiment vs 25.66 vol% simulated, without air ventilation, while the use of a ventilation system reduced maximum concentration to 4.82 vol% in the experiment vs 3.37 vol% simulated at 6 bar of release pressure. The use of appropriate detection systems, such as H 2 sensors and alarms, is found to be effective in triggering safety measures. • H 2 accidental release in the electrolyser was studied experimentally and numerically. • The effects of release pressure and ventilation on H 2 distribution were quantified. • 24 vol% build-up of H 2 was observed at 6 bar of release pressure without ventilation. • Ventilation of 1 m/s was shown to prevent H 2 buildup for 1–2 bar release pressure.