Overall gas-liquid mass transfer from Taylor bubbles flowing upwards in a circular capillary

摘要

Overall liquid side volumetric mass transfer coefficient kLa was determined experimentally for co-current Taylor flow moving upwards in a glass tube of internal diameter 3mm. Experiments were performed for physical absorption of oxygen in 20% aqueous solution of ethanol. Shadowgraph technique was deployed for precise measurements of bubble lengths and velocities. Experimental values of volumetric mass transfer coefficient kLa were evaluated by use of oxygen sensor and contributions of two possible mass transfer mechanisms: bubble to liquid slug and bubble to liquid film, were discussed. Effects of various hydrodynamic parameters like superficial velocity, length of bubble and slug, etc. on kLa have also been presented. A correlation has been proposed for the estimation of kLa for a wide range of bubble to slug lengths ratio and superficial velocities of gas and liquids.