Abstract:
The Superheated steam has been shown to be more effective than hot air
for drying corn. Modeling studies have been carried out in fluidized bed dryers to
determine the moisture and heat transfer characteristics of corn, but there are no
modeling studies for a single corn kernel. Knowledge of heat and mass transfer
characteristics in a single kernel would produce a better understanding of steam
characteristics needed for specific drying rates. The study sought to determine the
influence of steam temperature and velocity on the drying rate of a corn kernel. It
used computational fluid dynamics (CFD) to model the transfer of heat and moisture between the corn kernel and superheated steam. The simulation used cone
geometry to represent the corn kernel. The kernel had characteristic dimensions
and 20% initial moisture content. The condition of the steam, which was typical of
that found in industry, had temperatures of 120–200°C and velocities of 0.5–1.5 m/s.
There was a decrease in the duration of the initial condensation phase as the
temperature of superheated steam increased from 120°C to 200°C. The highest
steam temperature and velocity resulted in the shortest duration for steam condensation. Contrary to what has been reported, there was no moisture loss from the
corn kernel when exposed to superheated steam at 120°C, which may be due to
how heat was retained in the drying chamber. Thus, the processes of tapping steam
and retaining heat are important elements in the operation of industrial steam
driers.
