Mathematical modelling and simulation analysis of PEM electrolyzer system for hydrogen production

In recent times there is a growing concern about the environmental impact of conventional energy sources. The only solution to the depletion and environmental impact is to rely on sustainable renewable energy sources for various applications. One of the promising options is PEM electrolyzer for hydrogen production. In this paper, the equations related to mathematical models for PEM electrolyzer based on a combination of thermodynamics fundamental and electrochemical relations are presented. Simple PEM electrolyzer is analyzed on the basis of wellknown Butler-Volmer kinetic for the electrodes and transport resistance in the polymer-electrolyte. The effect of temperature on operating cell voltage, resistance and ionic conductivity of the polymer electrolyte are examined. Finally different values of exchange current densities at anode and cathode were tested. The simulation results indicate that as temperature increases, there is a significant or sharp decrease in ohmic resistance from 0.198Ω/cm² at 40°C to 0.125Ω/cm² at 80°C. However there is a small increase in ionic conductivity. From this observation it can be concluded that the ionic conductivity of the membrane assembly increases with temperature and this can lead to increase in hydrogen flow rate.