Experimental and theoretical investigation of natural convection in CCS: Onset time, mass-transfer rate, capillary transition zone, and heat of dissolution

We study the enhanced mass transfer of CO2 in water for a CO2 saturated layer on top of a water saturated porous medium, experimentally and theoretically. A relatively large experimental set-up with a length of 0.5 m and a diameter of 0.15 m is used in pressure decay experiments to minimize the error of pressure measurement due to temperature fluctuations and small leakages. The experimental results were compared to the theoretical result in terms of onset time of natural convection and rate of mass transfer of CO2 in the convection dominated process. In addition, a non-isothermal multicomponent flow model in porous media, is solved numerically to study the effect of the heat of dissolution of CO2 in water on the rate of mass transfer of CO2. The effect of the capillary transition zone on the rate of mass transfer of CO2 is also studied theoretically. The simulation results including the effect of the capillary transition zone show a better agreement with experimental results compared to the simulation result without considering a capillary transition zone. The simulation results also show that the effect of heat of dissolution on the rate of mass transfer is negligible