Dissolution process of CO2 bubble adhered to a flat plate in a flow fluid

Abstract

The dissolution process of CO2 bubbles adhered to a flat plate in a rectangular channel at different flow velocities is studied experimentally and theoretically. In the experiments, the CO2 bubble is manually introduced by means of a needle connected to a micro-syringe in the rectangular channel filled with ultra-pure degassed water. The rectangular channel comprises a transparent 3D printed cavity and a replaceable plate. The water flow velocity in the rectangular channel can be precisely controlled using a liquid flow controller. The CO2 bubble is adhered to the flat plate, which is replaceable and has different wetting properties. The dissolution process of the bubble is visualized using a high-speed camera at different flow velocities. The changing bubble radius over time is calculated using an image processing program. A mathematical dissolution model is developed to estimate the dissolution durations of the CO2 bubble adhered to the flat plate, which includes the effect of contact angle and water flow velocity by using Sherwood number. With appropriate constants, the dissolution model exhibits good agreement with the experimental results. It is found that both the contact angle and water flow velocity play important roles in the bubble dissolution rate. An increase in water flow velocity can help improve the bubble dissolution rate. With a decrease in contact angle, the bubble dissolution rate becomes faster. The dissolution model is used to predict the maximum allowable bubble size at different scanning speeds in immersion lithography.