Abstract The greenhouse solar system (bulk-curing/greenhouse system or solar barn) is a large solar collector in which the curing and drying process or plant production process is taking place for effective year-round solar energy utilization in agricultural production. The transparent outer structure and the black surface of inside facilities constitute a large multidirectional solar collector to provide competitive initial cost for the solar unit as compared to that for a conventional drying unit. Full scale tobacco cures with the solar system have demonstrated quality tobacco curing with a 47 to 54% fuel savings for this system compared to a conventional bulk curing barn. The microcomputer control of tobacco bulk curing process was implemented and successfully applied to maximize solar energy utilization. The rotary solar drum unit was designed to dry grains, peanuts and other agricultural crops in the drying mode operation applying the principles of reversible-flow, periodic agitation, and low-temperature solar drying resulting in significant fuel savings. The unit is convertible to a rotary layer automated seedling production system to be used in greenhouse mode operation. At the end of the curing and drying season the solar barn was converted into a solar greenhouse to demonstrate the automated production of flowers, cucumbers, tomatoes and various seedlings. Growth and yield studies have shown that solar barn grown seedlings adapted to fully automatic transplanting and that a better growth and yield was achieved from these seedlings. System concept, theoretical considerations, mathematical models and analyses are presented for the solar drying mode operation. The simulation results agreed favorably with the measured data.
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