Abstract:
Among the drying models available in the literature, the REA
model (which was first proposed in 1996) is semi-empirical. It was
described based upon a basic physical chemistry principle. The
‘‘extraction of water from moist material’’ is signified by applying
the activation energy concept. The single expression of the extraction
rate represents the competition between evaporation and
condensation. It also encompasses the internal specific surface area
and mass transfer coefficient, and thus is linked to material characteristics.
The REA can be classified into two categories—Lumped
(L) REA and Spatial (S) REA—which can be used to deal with drying
a material as a whole or considering the local phenomena within
the material, respectively. Both models have been proven to be very
effective. The REA is effective for generating parameters since only
one accurate drying run is required to establish the relative activation
energy function. Both internal and external resistances are
modeled by the REA. In its lumped format, the REA is employed
to describe the global drying rate, while in the S-REA, the REA
is used to model the local evaporation rate. This article covers fundamentals
of the REA which have not been fully explained, as well
as the most recent development and applications. The application of
the S-REA as a non-equilibrium multiphase model is highlighted.
