Improving Vegetable Seed Quality and Dryer Performance with an Automated Desiccant-Assisted Hybrid Solar Dryer System

A desiccant-assisted automated hybrid solar dryer was developed for vegetable seeds. The
dryer consisting two sections, one for drying the air and the other for the regeneration of
desiccant. The collector area of the dryer is 1.3 sq.m and three trays of 0.18 m 2 of area each in
the drying chamber. The dryer consists of a real-time data acquisition system for recording
the temperature, and humidity, and the dryer was equipped with an automatic temperature
control unit to maintain the temperature at a preset level(≤40°C). The bottom of the drying
chamber was also filled with desiccant for continuous drying after sunshine. The performance
of the developed dryer was evaluated by drying fresh onion seeds having an initial moisture
content of 18-20% (wb) and compared with the developed dryer without desiccant
considering both the drying parameters and quality parameters of the dried seeds. The
developed dryer with desiccant was found to produce a significant difference in drying rate
(P<0.0001) for onion seeds compared to dryers without desiccant drying. All the quality
parameters in terms of germination percentage, and vigor index I and II, found to have a
significance difference (P<0.0001) compared to without desiccant drying. The developed
solar dryer provides a promising alternative for the continual drying of other materials
including onion even after sunshine hours with real-time data acquisition system and also
found to be superior in retaining quality.