Analysis of the effect of characteristic parameters and operating conditions on exergy efficiency of alkaline water electrolyzer

Further improvement of electrolysis efficiency is one of the main research directions in alkaline water electrolyzer (AWE) hydrogen production technology at present. This paper developed a thermodynamic-electrochemical model and analyzed the effects of characteristic parameters (electrode conductivity, electrode gap, diaphragm porosity and tortuosity, electrolyte concentration, bubble coverage rate) and operating conditions (temperature and pressure) on over-potential and exergy efficiency of AWE. The analysis results show that, between activation and ohmic over-potential, the former has a more significant effect on electrolytic voltage and exergy loss, and the latter varies more greatly with current density. Ohmic resistance exergy loss mainly caused by diaphragm, electrolyte and bubble resistances, among these resistances, the first one accounts for the largest proportion. Among the characteristic parameters, diaphragm porosity presents the most effect on exergy efficiency, followed by electrode gap, and bubble coverage rate the least. Under operating conditions, the effect of temperature on exergy efficiency is more significant than that of pressure. This paper can provide reference for parameter selection and performance optimization by conducting quantitative comparison analysis.