رضا آذین

In this study dissolution behavior of CO2 in pure water along with pertinent mechanisms is investigated numerically and experimentally. Numerical simulation is based on the finite element method and also experimental dissolution in a PVT cell. Dissolution is simulated in porous and bulk water. Equilibrium dissolution of CO2 in saturated porous medium with water is modeled and simulated using different peremeabilities. Results show that presence of a porous medium can control convective swirls (fingers). Analysis of measurements could yield to diffusion coefficient from different periods of dissolution including: evaluation of first period, beginning of second period, dimensionless pressure-dimensionless time curve at second period, maximum Sherwood and beginning third period of dissolution. Furthermore, Results in bulk water show that natural density-driven convection is the dominant mechanism so that the role of diffusive transport is overshadowed. We used three types of boundary conditions (BCs) at gas/liquid interface here including: equilibrium, semi-equilibrium and non-equilibrium. Comparison of our simulated and measured experimental data shows that the non-equilibrium BC can predict dissolution behavior reliably. Other boundary conditions show considerable deviation between model predictions and experimental measurements especially when convective dissolution manifests. Mass transfer coefficient is the highest at the start of dissolution and decreases versus time. Results show that when convection is the active mechanism even at later times, it interferes with diffusivity measurements and makes interpretation of diffusion experiment results difficult both at early and later times.