Preliminary Measurementsof Transient Mass TransferProcess across Supercritical CO₂–Acetone Interfaceusing Phase-Shifting Interferometer Technique

Supercritical carbon dioxide (CO₂)-based extraction and separation of contaminants are new methods for environmental remediation, which have been proposed in recent years. A modified phase-shifting interferometer with high temporal and spatial resolution is applied to measure the mass transfer process of acetone in a supercritical CO₂ environment under different bottom heat fluxes (49.67–372.22 W/m²), with the initial conditions of 28.0–34.0 °C and pressures of 7.4–7.7 MPa. The order of magnitude of the equivalent mass diffusion coefficient for the interface mass transfer of acetone in the CO₂ environment ranges from 10^–7 to 10^–6 m²/s for the current experiments. The equivalent mass diffusion coefficient increases with the increased heat flux from the bottom surface. Moreover, this coefficient decreases with the increasing initial temperature but increases with the increasing initial pressure. The equivalent mass diffusion coefficient in the supercritical environment is larger than that in the subcritical environment under the same initial pressure and heat flux. To quantify the mass transfer of the acetone-sCO₂ system, a concentration-based source term is applied to the numerical calculations. The results show the agreement of the horizontal average concentration distribution between the experiment and the calculation.