Numerical simulation of the effect of operating parameters towards charge transfer coefficient (CTC) in polymer electrolyte membrane (PEM) electrolyzer / Fatin Athirah Mazlan

Activation overpotential is a very important parameter in evaluating the performance of PEM electrolyzer, it is one of the major overpotentials that contribute towards overall operating voltage of the electrolyzer. One of the most significant parameters associated with this overvoltage is charge transfer coefficient (CTC). This study aims to contribute to this growing area of research by investigating the effects of operating temperature and CTC on the overall operating voltage. This study also provides an important opportunity to advance the understanding of the effect of different temperature and pressure on the CTC. The result of this study was successfully compared with experimental data. The simulation result shows that, within the temperature range of 10°C to 90°C, the CTC values at the anode electrode ranges between 0.807 and 1.035 while at the cathode electrode, the variation is only within 0.202 to 0.259. It was observed that activation overvoltage decreases when the CTC increase from 0.5 to 2.0 both at anode and cathode electrodes. Interestingly it was observed that the CTC remains the same even at balanced and unbalanced pressure. In spite of that, the performance of PEM electrolyzer had been investigated by efficiency and power supply. It shows that the PEM electrolyzer operates better at a higher temperature. While the power density had been analyzed by using different CTC value which is 0.5, 1.0, 1.5 and 2.0. Therefore, it shows the power density increases significantly with respect to current density. It has been carried out at 60°C , 80°C and 90°C and it shows that, at higher temperature and a specified CTC, the power density increase by a very small fraction. As a consequence, it can be said that, the limiting factor in PEM electolyzer system was activation overpotential at the anode. Hence, a suitable CTC value can decrease activation overpotential to improve the polarizations.