ABSTRACT
In engineering problems related to mass transfer, students are interested in the amount of a specific species transferred to or from the system of interest through its boundaries. Mass transfer in cylindrical tubes is encountered in a variety of operations such as wetted wall columns, reverse osmosis, and cross-flow ultrafiltration. Mass transfer correlations depend on whether the flow is laminar or turbulent. If the molar flux expression cannot be obtained from the solution of the species continuity equation, then it is expressed with the help of Newton’s law of mass transfer. The use of pseudosteady-state approximation requires the molar flux of species to be known at the system boundary. The two-film theory proposed by W. K. Lewis and W. G. Whitman is one of the oldest and most frequently used models for the transfer of solutes from the gas phase to the liquid phase.
