A numerical study of mixed convection heat and mass transfer with film
evaporation in a vertical channel is developed. The emphasis is focused on
the effects of vaporization of three different liquid films having widely
different properties, along the isothermal and wetted walls on the heat and
mass transfer rates in the channel. The induced laminar downward flow is a
mixture of blowing dry air and vapour of water, methanol or acetone, assumed
as ideal gases. A two-dimensional steady state and elliptical flow model,
connected with variable thermo-physical properties, is used and the phase
change problem is based on thin liquid film assumptions. The governing
equations of the model are solved by a finite volume method and the
velocity-pressure fields are linked by SIMPLE algorithm. The numerical
results, including the velocity, temperature and concentration profiles, as
well as axial variations of Nusselt numbers, Sherwood number and
dimensionless film evaporation rate are presented for two values of inlet
temperature and Reynolds number. It was found that lower the inlet
temperature and Re, the higher the induced flows cooling with respect of most
volatile film. The better mass transfer rates related with film evaporation
are found for a system with low mass diffusion coefficient.
Numerical study of heat and mass transfer during evaporation of a thin liquid film
