Mass transfer and bubble flow dynamics in aqueous solutions for hydrogen production cycles

The hydrogen economy is one potential avenue to a clean energy system, and a promising option for hydrogen production is thermochemical water decomposition. This process involves multiple steps, some consisting of multiphase reaction systems. Here, the thermodynamics and kinetics of vapour diffusion and entrainment for ascending bubbles in a vertical column are examined through experimental studies for various gas production rates. The vapour entrainment is interpreted in terms of the phase transition rate, and its dependence on such operating parameters as gas bubble size, liquid depth, temperature, pressure and concentration is examined. These effects are investigated experimentally, and a phase transition correlation is developed to analyze these parameters. Also, a predictive model is developed to simulate the physical processes of bubble transport in a vertical liquid column, as it occurs in water splitting processes such as oxygen generation in the copper-chlorine thermochemical cycle, as well as hydrogen generation in electrolytic and photocatalytic processes.