A NATURAL CONVECTION SOLAR DRYER FOR ROUGH RICE

Document Type : Original Article

Authors

1 Assistant prof. Dept. of Agric. Eng., Fac. of Agric. Zagazig Univ., Egypt.

2 Lecturer, Dept. of Agric. Eng., Fac. of Agric. Zagazig Univ., Egypt.

Abstract

A solar drying system was constructed and tested to dry rough rice grains for seeding under Zagazig city prevailing weather conditions. The system consists of two integrated units, a solar collector with total area of 1.8 m2 attached to a drying chamber. The system is classified as a natural convection indirect passive cabinet type without any moving parts. The study parameters included varying the air inlet area from 244 to 732 cm2, testing three levels of initial moisture contents (20, 22, and 25% w.b.), and two different grain layer thicknesses of 5 and 10 cm. The system was operated from 8 AM to 5 PM under Zagazig local conditions (Latitude 30.5° N) for 2 weeks during the rice harvesting season of 2009. The results showed that the smallest air inlet area of 244 cm2 gave the highest collector thermal efficiency, the highest temperature difference between ambient air and heated air inside the collector, and highest drying rate. Also the initial moisture content of 20% w.b. gave the highest drying rate and fastest drying time. Same results were found using layer thickness of 5 cm. So the combination of 244 cm2 air inlet area, 5 cm layer thickness, and 20% initial moisture content is recommended for the best thermal performance and highest drying rate. 

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References

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