VILLAR, G. C.; http://lattes.cnpq.br/9342195294368977; VILLAR, Gianna Cavalcanti.
Abstract:
Many kinds of fruits and vegetables are composed of more than 80% of water
and are highly perishable. Thus, due to the great deal of losses after harvests, it is
very important to study ways of reducing these losses. Studies indicate fruit drying
as one of the most economical and efficient conservation methods, when compared
to other methods: freezing, canning, and so on. In this work, we made an
experimental study of drying bananas slices in a convective tray drier, in order to
analyze the effects of operational variables (such as temperature and air drying
speed) over the performance of the drier; study the effect of the banana slice
thickness above the tray; and analyze the performance of the drier through two
criteria: drying air saturation level and global energetic efficiency of the drier. The
operational bands used were: input air temperature between 50 and 80° C; air
speed between 0,2 and 2,2 m/s; and banana slice layer thickness between 0,6 and
2,0 cm. The evaluation results showed a better utilization of the air and improved
energetic efficiency not only when operated with low air drying speed but also in
other conditions, such as with thicker banana slice layers over the trays. These
results indicate that the air goes out of the drier far from the saturation conditions,
making it possible to increase the load and/or the number of trays, in order to have
a better efficiency and a better use of the air drying potential. The experimental data
were used in a simulator program of a convective tray drier developed by
Cavalcante (1999) for comparison of results. The drying model employed was
proposed by Sokhansanj (1984). The drying kinetic was simulated using
Kiranoudis et alii (1997) equation with empiric coefficients for the estimate of the
drying constant. The model and the simulator used correctly represent the
experimental behavior observed, not only in predicting fruit moisture evolution, but
also air temperature and air humidity.