NUNES, A. G.; NUNES, ANTONIO GOMES; http://lattes.cnpq.br/9984485183361630; NUNES, Antonio Gomes.
Abstract:
This work represents the development of a solar dryer focusing on the appropriate technologies
for the Brazilian agriculture, spreading the culture of renewable energies and contributing to
the promotion of the sustainable development. It is about an indirect solar exposition dryer with
the solar collector and drying chamber merged and represents numerous innovations, which are
a thermal capacitor inside the solar collector and a movement system of the drying air (cooler),
energized by photovoltaic solar energy. The innovations used allowed the system to obtain air
temperatures inside the drying chamber around 50ºC ±5ºC, the drying air relative humidity
about 30ºC ±5ºC. With these characteristics, the drying process operated in the traditional
dryers with an average efficiency around 87%. The experimental tests were realized by drying
silver bananas (Musa spp.). For the experimental tests realized, the solar dryer shown itself
trustworthy, because the necessary time required for the bananas to reach humidity level in wet
basis of about 25% was 840 minutes (14 h), being compatible with the catalogued time in the
equivalent equipment literature. The drying kinetics was adjusted by the empirical method of
Page and the results were representative with high values of determination coefficients
approached 0.99. The temperature and relative air humidity measurement system of the drying
air using Arduino, ensured the measurement of the temperature and relative air humidity in the
intakes and outlets of the solar collector and drying chamber, allowing the solar dryer energy
balance realization, resulting in the thermal efficiency calculation of the solar dryer and other
thermodynamics properties of the drying air. The results obtained by the thermal efficiency of
the drying system were around 19.60%, which are compatible with the ones described in the
literature for equivalent solar dryer that used only solar energy as energy provider. The
investments with the maintenance and operation of the drying system are only related to the
natural degradation of its components. Its economic viability was demonstrated in a short term
investment return of about six months.