Mathematical modeling for a monopolar-dry cell alkaline electrolyzer, an appraisal on electric and thermodynamics effects for laboratory scale

The mathematical modeling considering the thermodynamics of the water dissociation reaction, the kinetics of the electrode, and the ohmic resistance for hydroxide ions for a laboratory-scale monopolar alkaline electrolyzer (Reactor) was investigated. A whole practical approach was developed in this work and two objectives were achieved. First, the experimental data (voltage, current and gas production) was used to generate the characteristic curves of each experiment performed, and these curves were fitted to the experimental data by non-linear regression based on ordinary least squares. Second, the reactor where the target gas was produced and the configuration of the process simulation were both modeled simultaneously (Characteristic curves for KOH). The developed theory was applied to analyze the performance of the electrolyzers using a 1 M solution of KOH in a reactor configuration with different number of electrodes (2, 4, 6, and 20). Finally, compared to other models in the literature, the model presented in this work includes a step-by-step procedure that can be particularly useful to (1) design or redesign a system of a small stack reactor with a common configuration for several experimental applications and (2) to simulate the process under different conditions including the power source variabilities.

Automated summary

This study investigated the mathematical modeling of a laboratory-scale monopolar alkaline electrolyzer, taking into account the thermodynamics of the water dissociation reaction, the kinetics of the electrode, and the ohmic resistance for hydroxide ions. A practical approach was developed to fit the characteristic curves of each experiment to the experimental data. The model simultaneously modeled the reactor and the process configuration. The model was applied to analyze the performance of electrolyzers with different numbers of electrodes using a 1 M solution of KOH.