Comparative studies of Cu-Cl Thermochemical Water Decomposition Cyles for Hydrogen Production

Abstract

This research focuses on thermodynamic analysis of the copper chlorine cycles. The cycles were simulated using Aspen Plus software. All thermodynamic data for all the chemical species were defined from literature and the reliability of other compounds in the simulation were ascertained. The 5-step Cu–Cl cycle consist of five steps; hydrolysis, decomposition, electrolysis, drying and hydrogen production. The 4-step cycle combines the hydrolysis and the drying stage of the 5-step cycle to eliminate the intermediate production and handling of copper solids. The 3-step cycle has hydrolysis, electrolysis and hydrogen production stages. Exergy and energy analysis of the cycles were conducted. The results of the exergy analysis were 59.64%, 44.74% and 78.21% while that of the energy analysis were 50%, 49% and 35% for the 5-step cycle, 4-step cycle and 3-step cycle respectively. Parametric studies were conducted and possible exergy efficiency improvement of the cycles were found to be between 59.57-59.67%, 44.32-45.67% and 23.50-82.10% for the 5-step, 4-step and 3-step respectively. The results from the parametric analysis of the simulated process could assist ongoing efforts to understand the thermodynamic losses in the cycle, to improve efficiency, increase the economic viability of the process and to facilitate eventual commercialization of the process.