The Gaseous Mass Transfer and Diffusion Coefficient Unit, "QDTG", allows the students to familiarize with the theoretical concepts about mass transfer unit operations, specifically the diffusion of a volatile liquid in an inert gas, obtaining very useful experimental data and results for the good practical understanding of the process and, therefore, for the technical training of the students.
The unit consists of a vertical capillary tube with a volatile solvent (liquid A) and gas (air), which will flow horizontally under laminar flow conditions in the upper end of the tube. This air is introduced by a blower.
The capillary tube is introduced in a controlled temperature thermostatic bath, which will work following the double boiler method. The solvent will be evaporated slowly due to the thermal energy of the bath. And due to the concentration gradient, the gaseous solvent will be dispersed upwards, from the surface of the liquid solvent towards the pure air. The air flow will transport the molecules of the solvent and the volume of the liquid solvent in the tube will be reduced. There is an optical system with fine focusing adjustment to measure this level difference.