New Spectrophotometric Method for Quantitative Characterization of Density-Driven Convective Instability

CO₂ convective dissolution has been regarded as one of the fundamental mechanisms to accelerate the mass transfer of CO₂ into brine. We present a new spectrophotometric method to characterize the convective instability and measure the dissolved CO₂ mass, which enables the real-time quantitative visualization of CO₂/brine transport mechanisms. Successive images were captured to identify the finger development regimes, and the convection morphologies were analyzed by the fingers length and affected area. CO₂ solubility was experimentally studied, and the results are in agreement with the theoretical calculations. CO₂ mass transfer flux was investigated as the Sherwood number changed. The increase in salinity and temperature has a negative effect on CO₂ dissolution; here, numerical simulation and experimental phenomena are qualitatively consistent. In general, these findings confirm the feasibility of the method and improve the understanding of the physical process of CO₂ convective dissolution, which can help assess the CO₂ solubility trapping mass.